WO2009101985A1 - Conductive paper and its manufacturing method, conductive cellulose composition and its manufacturing method, articles, and electronic devices - Google Patents

Conductive paper and its manufacturing method, conductive cellulose composition and its manufacturing method, articles, and electronic devices Download PDF

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Publication number
WO2009101985A1
WO2009101985A1 PCT/JP2009/052322 JP2009052322W WO2009101985A1 WO 2009101985 A1 WO2009101985 A1 WO 2009101985A1 JP 2009052322 W JP2009052322 W JP 2009052322W WO 2009101985 A1 WO2009101985 A1 WO 2009101985A1
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conductive
cellulose
paper
ionic liquid
conductive paper
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PCT/JP2009/052322
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French (fr)
Japanese (ja)
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Takao Someya
Tsuyoshi Sekitani
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The University Of Tokyo
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Priority to JP2009553445A priority Critical patent/JP5660595B2/en
Publication of WO2009101985A1 publication Critical patent/WO2009101985A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H01B1/12—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances organic substances
    • H01B1/122—Ionic conductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material

Definitions

  • the present invention relates to a conductive paper and a manufacturing method thereof, a conductive cellulose composition and a manufacturing method thereof, an article, and an electronic device.
  • Patent Document 1 proposes that a paper sheet made of paper containing a conductive polymer is made to obtain a conductive polymer composite paper. JP 2000-160500 A
  • this paper exhibits only a conductivity of about 1 S / cm at most, and the conductivity is too insufficient to be used for electrical and electronic applications.
  • the present invention has been made in view of the above circumstances, and provides a conductive paper having excellent conductivity that can be sufficiently applied to an electronic device, a conductive cellulose composition, and a method for producing the same. With the goal.
  • the conductive paper of the present invention is characterized in that cellulose and a conductive substance are mixed.
  • This conductive paper has a structure in which cellulose and a conductive substance are entangled with each other and uniformly dispersed.
  • conductive cellulose which is a mixture of cellulose and a conductive substance, is intertwined to form a solid, so that a network of conductive substances is formed inside, and good conductivity is achieved.
  • the degree of mixing of the cellulose and the conductive material may be such that the phase separation does not occur when these admixtures are dispersed in the dispersion medium.
  • a better conductive property can be obtained and a conductive paper excellent in recyclability can be obtained.
  • the conductive paper may contain an ionic liquid.
  • the conductive paper of the present invention uses an ionic liquid in its production process. When the ionic liquid is contained, better conductivity can be obtained. Further, since it is a liquid component, curing due to the addition of a conductive material that is often hard such as carbon nanotubes or a conductive polymer can be suppressed, and a conductive paper that is soft and excellent in texture can be obtained. That is, the ionic liquid also acts as a plasticizer for conductive paper.
  • the conductive paper can be regenerated by dissolving it in a liquid. That is, the conductive paper of the present invention can be recycled very easily as with normal paper.
  • the conductive paper preferably has a conductivity of 1 S / cm or more. Although there is no restriction
  • the conductive substance is preferably a carbon nanotube, and the length of the carbon nanotube is more preferably 1 ⁇ m or more and 10 cm or less.
  • the conductive substance is preferably a conductive polymer.
  • the conductive paper may be configured such that the ionic liquid is hydrophilic. According to this configuration, hydrophilic conductive paper can be obtained. Further, if the ionic liquid is configured to be hydrophobic, hydrophobic conductive paper can be obtained.
  • conductive materials are mixed in the conductive paper. According to this configuration, the electrical conductivity can be further improved and the mechanical characteristics can be improved.
  • a metal and a conductive polymer can be used, for example.
  • the conductive cellulose composition of the present invention is characterized in that cellulose and a conductive substance are mixed. According to this configuration, it is possible to provide a conductive cellulose composition suitable as a constituent material of conductive paper or as a liquid material having conductivity. By mixing the cellulose and the conductive material, the conductive cellulose, which is a mixture of these, becomes a dispersion liquid that is uniformly dispersed in the dispersion medium and does not phase-separate.
  • the conductive cellulose composition may contain an ionic liquid.
  • the ionic liquid When the ionic liquid is included, the ionic liquid exhibits affinity for both the conductive material and cellulose, and thus the conductive cellulose composition in which the conductive material and cellulose are more uniformly dispersed is obtained. Since an ionic liquid is used in the process for producing a conductive cellulose composition, the conductive cellulose composition usually contains an ionic liquid.
  • the conductive cellulose composition may contain other conductive substances. According to this configuration, functionality can be further imparted to the conductive cellulose composition by another conductive substance.
  • the conductive cellulose composition is preferably pasty, gelled, or liquid. By setting it as such a liquid composition, it becomes an electroconductive cellulose composition which can be used as an ink (liquid material) of all the printing machines including screen printing, inkjet printing, a dispenser etc., and can be printed on a predetermined pattern.
  • the article of the present invention comprises the conductive paper of the present invention or the conductive cellulose composition of the present invention.
  • the electronic device of the present invention includes the conductive paper of the present invention or the conductive cellulose composition of the present invention.
  • the conductive paper manufacturing method of the present invention includes a step 1 for preparing a mixture of an ionic liquid and a conductive substance, a step 2 for preparing a dispersion by dispersing cellulose in the mixture, and a step for drying the dispersion. 3.
  • this manufacturing method it is possible to obtain a mixture in which the conductive substance and the ionic liquid are uniformly dispersed by the action of the ionic liquid, and when cellulose is added to the mixture, the cellulose and A dispersion in which the conductive substance and the ionic liquid are uniformly dispersed can be obtained. Thereby, the dispersion liquid containing the electroconductive cellulose with which the cellulose and the electroconductive substance were mixed can be obtained. And the electrically conductive paper which has electroconductive cellulose can be manufactured by drying a dispersion liquid.
  • the method for producing conductive paper may further include a step 4 of removing the ionic liquid from the dried product of the dispersion.
  • the ionic liquid can be removed from the conductive paper and recovered. And since the collect
  • the ionic liquid when the ionic liquid is hydrophilic, it is preferable to add water as a dispersion medium in the step of preparing the dispersion. According to this manufacturing method, it is possible to manufacture hydrophilic conductive paper having conductive cellulose in which a conductive substance and cellulose are uniformly dispersed.
  • the ionic liquid when the ionic liquid is hydrophobic, it is preferable to add a dispersion medium other than water in the step of preparing the dispersion.
  • a dispersion medium other than water for example, a hydrophilic organic solvent such as ethanol or methanol can be used, and may be appropriately changed according to the type of cellulose.
  • the method for producing a conductive cellulose composition of the present invention includes a step 1 for preparing a mixture of an ionic liquid and a conductive substance, and a step 2 for preparing a dispersion by dispersing cellulose in the mixture.
  • a conductive cellulose composition as a dispersion in which conductive cellulose in which a conductive substance and cellulose are mixed is dispersed.
  • the electrically conductive paper which can acquire high electrical conductivity, big mechanical flexibility, and durability can be provided by mixing cellulose and an electroconductive substance.
  • the conductive paper of the present invention can be easily recycled.
  • goods and electronic device using the high electrical conductivity of conductive paper can be provided. According to the production method of the present invention, a conductive paper and a conductive cellulose composition having high conductivity can be easily produced.
  • the figure which shows a conductive cellulose composition The flowchart which shows the manufacturing method of conductive paper.
  • the graph which shows the change of the resistance value with respect to a bending radius.
  • the graph which shows the electrical property of conductive paper A graph showing a change in conductivity when conductive paper is recycled.
  • the conductive cellulose composition of the present invention has a conductive cellulose in which cellulose and a conductive substance are mixed, and in some cases includes an ionic liquid occluded in the conductive cellulose.
  • the conductive cellulose composition of the present invention can be used in various forms such as liquid, gel, solid, paper, etc., depending on the presence or absence of an ionic liquid, the presence or absence of a dispersion medium such as water or an organic solvent, and characteristics. Can take form.
  • Fig.1 (a) is a schematic diagram which shows the electroconductive cellulose composition which concerns on this invention
  • FIG.1 (b) is a schematic diagram which expands and shows the fiber shown to Fig.1 (a).
  • the conductive cellulose composition according to the present invention includes a large number of conductive celluloses 10.
  • each conductive cellulose 10 has a structure in which a large number of carbon nanotubes 12 that are conductive materials are entangled around a cellulose fiber 11.
  • the cellulose fibers 11 and the carbon nanotubes 12 are mixed to such an extent that the fibers are intertwined in a complicated manner and the cellulose fibers 11 and the carbon nanotubes 12 are not phase-separated even when the conductive cellulose 10 is dispersed in a dispersion medium such as water or an organic solvent. Matching. In the present invention, such a state is defined as a state in which cellulose and a conductive substance are “mixed”. In addition, it is impossible to separate the cellulose fibers 11 and the carbon nanotubes 12 that are mixed without damaging them, and it can be said that they are in a state of being mixed so as not to be separated.
  • the conductive cellulose 10 shown in FIG. 1 is an example of the conductive cellulose composition according to the present invention, and details will be described later, but the conductive material is not limited to the carbon nanotubes 12. For example, a metal nanotube or a conductive polymer can be used.
  • a representative form of the conductive cellulose composition of the present invention is conductive paper obtained by forming a dispersion of conductive cellulose 10 into a sheet and drying it.
  • the conductive paper according to the present invention possesses the function as paper without impairing the characteristics and form of the base material cellulose, and at the same time has high conductivity imparted from a conductive substance.
  • Such a conductive paper is an innovative new material that can be realized for the first time by the present invention, and can be suitably used for a wiring pattern of an electronic circuit because of its excellent conductivity.
  • a conductive paper since it is composed of the conductive cellulose 10 in which cellulose (cellulose fibers 11) and a conductive substance (carbon nanotubes 12) are mixed, a complicated network of conductive substances is formed in the conductive paper. Therefore, it is possible to obtain a high conductivity that could not be obtained at all with a conductive paper obtained by impregnating paper with a conventionally known conductive material.
  • a conductivity of 1 S / cm or more is preferable because it can be used as wiring for an electronic circuit.
  • the conductive paper of the present invention since the conductive paper of the present invention has a network of conductive materials inside as described above, it does not lose its conductivity even if it is folded or stretched. Therefore, it is a conductive paper having excellent flexibility and workability that cannot be obtained by a conductive paper in which a conductive material layer is formed on a conventional paper. Furthermore, the conductive paper of the present invention can be easily redispersed in water or a solvent, just as ordinary paper can be easily recycled simply by dissolving it in water. Therefore, it can be easily recycled without giving high energy such as heat.
  • the conductivity, bending resistance, and recyclability of the conductive paper according to the present invention are described in detail in the following examples.
  • the conductive paper of the present invention is not limited to paper or thin film, and the conductive cellulose composition is made into a solid material (three-dimensional structure such as rod, box, frame, and cylinder) using a mold or the like. Includes processed products. Furthermore, machining may be added to solid conductive paper. For example, the sheet-like conductive paper may be thinned by stretching by press working or the like. Conductive paper formed as such a solid substance or processed conductive paper can also be suitably used as a conductive member of an article or a constituent member of an electronic circuit.
  • the conductive paper of the present invention usually contains the ionic liquid used in the manufacturing process together with the conductive cellulose 10.
  • the ionic liquid is also called a room temperature molten salt or simply a molten salt, and is a salt that exhibits a molten state in a wide temperature range including normal temperature.
  • the details of the ionic liquid will be described in the description of the production method at a later stage, and this ionic liquid also has the effect of increasing the conductivity in the conductive paper of the present invention.
  • the ionic liquid is a liquid at room temperature, the conductive paper containing the ionic liquid exhibits a moist and smooth texture and is closer to paper.
  • the ionic liquid can also be removed from the conductive paper or the conductive cellulose composition by using a Soxhlet method or the like.
  • the conductivity of the conductive paper (conductive cellulose composition) from which the ionic liquid has been removed is lower than that of the conductive paper containing the ionic liquid, but the removed ionic liquid can be recovered and the conductive cellulose composition can be produced. Can be reused.
  • a dispersion of conductive cellulose 10 is a dispersion of conductive cellulose 10.
  • a dispersion can take various forms such as a liquid, a gel, and a paste depending on the properties of the ionic liquid and the dispersion medium.
  • Such a fluid dispersion can be processed into conductive paper by solidifying it by heat, drying, or the like, and is suitable for producing a molded conductive paper.
  • the prepared conductive cellulose dispersion is used as ink (liquid material) for any printing press including screen printing, ink jet printing, dispenser, etc., and printed in a predetermined pattern, and then dried to produce conductive paper. It is possible to easily form patterns and wirings made of Thus, an article provided with a pattern or wiring made of conductive cellulose, or an electronic circuit provided with a conductive cellulose composition can be produced.
  • a conductive material that is the same as or different from the conductive material constituting the conductive cellulose can be added to the conductive paper or the conductive cellulose dispersion.
  • a fibrous conductor such as carbon nanotube or silver nanotube
  • higher conductivity and strength as paper can be obtained.
  • the conductive material constituting the conductive cellulose 10 is not limited to the carbon nanotubes 12 including single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT), but also metal nanotubes (metal nanofibers) including silver.
  • Any conductive material can be used as long as it is a conductive material such as a conductive polymer.
  • the conductive material needs to be in a form that can be mixed with cellulose. Therefore, the type of the conductive material is not limited, but a conductive material manufactured or processed to a size equal to or smaller than that of cellulose fibers is used.
  • a conductive paper or a conductive cellulose composition having high conductivity and being supple like paper it is important to use a conductive material having high conductivity.
  • the carbon nanotubes are long, have high purity, and have a high specific surface area. Therefore, in general, single-walled carbon nanotubes having a high specific surface area and a long length are more preferable than multi-walled carbon nanotubes having a low specific surface area and a short length.
  • the carbon nanotube is desirably as long as possible. This is because, when the carbon nanotube network (knitted structure) in the conductive cellulose composition is composed of long carbon nanotubes, more paths for conducting electricity can be formed, and even when bent, the network is more difficult to break. Because.
  • the length of the conductive material for obtaining high conductivity and flexibility in the conductive cellulose composition there is no upper limit to the length of the conductive material for obtaining high conductivity and flexibility in the conductive cellulose composition, but in general, longer materials have lower dispersibility and the production of the conductive cellulose composition can be reduced. It becomes difficult.
  • carbon nanotubes when carbon nanotubes are used, carbon nanotubes having a length of 1 ⁇ m or more and 10 cm or less have good dispersibility, are easily obtained with high purity, and are preferable for obtaining high conductivity and flexibility. When the length is 1 ⁇ m or less, the conductivity is extremely lowered, which is not preferable. Conversely, carbon nanotubes having a length of 10 cm or more have poor dispersibility and are easily cut during the dispersion process.
  • the carbon nanotube is a very long and narrow nanomaterial having a nanoscale diameter and a long length, it is very difficult to measure the length of each one.
  • the following method can be used when measuring the length of the carbon nanotube.
  • a liquid sample is prepared by thinly diluting a mixture of carbon nanotubes and ionic liquid, or a dispersion in which cellulose is dispersed in such a mixture with an organic solvent or the like.
  • the liquid sample dropped onto the substrate and then dried is observed with a scanning atomic force microscope or the like.
  • the length of the bundle (bundle of carbon nanotubes) is measured instead of the length of each carbon nanotube.
  • the length of the carbon nanotube bundle measured by the scanning atomic force microscope and the length of the carbon nanotube constituting the bundle, and the bundle constituted by the long carbon nanotube becomes long. Thereby, the length of the carbon nanotube can be evaluated.
  • a conductive cellulose composition there is no limitation on the characteristics and length of the carbon nanotube, and a conductive cellulose composition can be produced.
  • a carbon nanotube produced by a super-growth method is used as a long carbon nanotube that can obtain higher conductivity and flexibility.
  • a method for producing carbon nanotubes by the super-growth method is described, for example, in International Publication No. 06/011655.
  • the super-growth method is a technique for synthesizing carbon nanotubes by a moisture-added CVD method, and long and high-purity single-walled carbon nanotubes can be obtained.
  • a carbon nanotube alignment aggregate vertically aligned on a growth substrate can be grown, and this carbon nanotube alignment aggregate can be peeled off from the growth substrate and used.
  • the height of the aligned carbon nanotube assembly can be defined as the length of the carbon nanotube.
  • the carbon nanotubes be as pure as possible.
  • Purity is carbon purity and shows what percentage of the weight of a carbon nanotube is comprised with carbon. Although there is no upper limit to the purity for obtaining high conductivity and high elongation, it is difficult to obtain 99.9999% or more of carbon nanotubes for the convenience of production.
  • impurities such as metals are included and the carbon purity is less than 90%, the metal impurities are aggregated during the manufacturing process, and the carbon nanotubes are not easily entangled with the fibers of cellulose, resulting in insufficient mixing. It becomes difficult to obtain high bending resistance. From these points, the purity of the carbon nanotube is preferably 90% or more.
  • the purity of carbon nanotubes is obtained from the results of elemental analysis using fluorescent X-rays.
  • Super-growth (SG) single-walled carbon nanotubes (SWNT) used in specific examples to be described later were subjected to elemental analysis by fluorescent X-rays. As a result, carbon was 99.98%, iron was 0.013%, and other elements were measured. Was not.
  • the carbon nanotube has as high a specific surface area as possible. This is because carbon nanotubes having a high specific surface area have many surfaces, and therefore, the number of interfaces with the ionic liquid used in the production process of the conductive cellulose composition increases, and the carbon nanotubes easily interact with each other. Carbon nanotubes with a high specific surface area contain a small amount of carbon impurities other than carbon nanotubes and impurities such as metals other than carbon, and are suitable for the reasons described above.
  • Single-walled carbon nanotubes having a specific surface area of less than 600 m 2 / g contain impurities such as metals or carbon impurities of several tens of percent (about 40%) by weight, and may exhibit the original functions of single-walled carbon nanotubes. It cannot be done and is inappropriate.
  • the unopened one is about 1300 m 2 / g, and the opened one is about 2600 m 2 / g. is there.
  • the specific surface area of the single-walled carbon nanotube can be obtained by measuring an adsorption / desorption isotherm of liquid nitrogen at 77K.
  • 30 mg of the aligned single-walled CNT aggregate can be obtained from an adsorption / desorption isotherm curve measured using BELSORP-MINI (manufactured by Nippon Bell Co., Ltd.) (adsorption equilibrium time was 600 seconds).
  • examples of the conductive polymer include a polyaniline polymer, a polypyrrole polymer, and a polythiophene polymer.
  • examples of particularly highly conductive polymers include polyparaphenylene, polyaniline, polythiophene, polyparaphenylene vinylene, polypyrrole, polyacetylene, polyphenylene vinylene, and polyethylenedioxythiophene (hereinafter simply referred to as PEDOT).
  • PEDOT polyethylenedioxythiophene
  • a typical example is PEDOT, and its aqueous dispersion is commercially available from TA Chemical Company under the trade name “Baytron PH500”.
  • the size of the conductive polymer is smaller than that of the cellulose fiber 11 and the carbon nanotube 12, and therefore the cellulose fiber 11 as shown in FIG.
  • the conductive polymer is adsorbed so as to cover the surface of the cellulose fiber 11 and become the conductive cellulose 10.
  • the conductive cellulose 10 in which the conductive polymer is adsorbed on the cellulose fiber 11 is dispersed in the dispersion medium, the cellulose fiber 11 and the conductive polymer are not phase-separated. It is defined as a state in which cellulose and a conductive polymer are mixed. The conductive polymer thus adsorbed cannot be separated without damaging the cellulose and the conductive polymer.
  • the cellulose used in the present invention is not particularly limited, and may be any cellulose material (aggregate is pulp) used for ordinary papermaking. Commonly known pulp is formed from cellulose fibers. For example, any fibrous pulp such as wood pulp, waste paper pulp, non-wood pulp, more specifically softwood sulfite pulp, softwood bleached kraft pulp, hardwood sulfite pulp, hardwood bleached kraft pulp, and linter pulp may be used. As the cellulose, any cellulose such as natural cellulose, regenerated cellulose, cotton cellulose, linter, rayon, and amorphous cellulose can be used. Furthermore, the pulp is not limited to cellulose and cellulose, and any fiber that generates hydrogen bonds can be used as a raw material. Therefore, pulp extracted from raw materials such as grass, straw, and bamboo may be used.
  • microfibril cellulose that has been defibrated in advance into fine cellulose fibers in order to obtain paper having excellent conductivity.
  • microfibril cellulose is not particularly limited, and may be any commercially available one.
  • a typical example of commercially available microfibril cellulose is Celish manufactured by Daicel Chemical Industries.
  • Carbon nanotubes are used as the conductive substance
  • the conductive cellulose composition of the present invention higher conductivity is obtained as the carbon nanotubes are uniformly dispersed in the composition. That is, in order to realize the conductive cellulose composition of the present invention having both high conductivity and flexibility, a carbon nanotube having a long length, high purity, and high specific surface area can be obtained without degrading its function. It is important to uniformly disperse the water.
  • carbon nanotubes are materials with very low solubility, have low affinity with cellulose, and do not disperse in cellulose. Therefore, it has been extremely difficult to realize a conductive cellulose composition and conductive paper in which carbon nanotubes are uniformly dispersed and have both high conductivity and flexibility.
  • the present inventor has made sincerity and found that it is preferable to use an ionic liquid in order to increase the dispersibility of the conductive material and cellulose including carbon nanotubes.
  • an ionic liquid in order to increase the dispersibility of the conductive material and cellulose including carbon nanotubes.
  • carbon nanotubes and ionic liquid have a high affinity, and the carbon nanotubes are gelled by being dispersed in the ionic liquid.
  • van der is that the ionic liquid is adsorbed on each carbon nanotube and bonds the carbon nanotubes together. It is thought that the virus power is weakened.
  • the carbon nanotubes that are usually easily bundled are dispersed in the ionic liquid to form a gel composition.
  • the ionic liquid is considered to function as a dispersant for carbon nanotubes.
  • the inventor has found that when cellulose and a conductive substance that are miscible with the ionic liquid are used, a dispersion in which cellulose is uniformly dispersed in the gel composition can be obtained.
  • the conductive cellulose composition having high electrical conductivity and the flexibility of paper and a method for producing conductive paper have been realized.
  • the detailed mechanism by which the conductive cellulose composition is formed by mixing is unknown at this time.
  • the ionic liquid adsorbed on the conductive material has affinity with cellulose and mixes the conductive material into the cellulose. It is considered that a conductive substance such as a carbon nanotube that can be dissolved and normally difficult to disperse in cellulose is uniformly dispersed in cellulose.
  • the mixing in the dispersion means that the ionic liquid, cellulose, pulp as a base material, and, if necessary, a dispersion containing water or an organic solvent are mixed to such an extent that they do not undergo phase separation.
  • the degree of blending There is no upper limit to the degree of blending, and the conductive cellulose composition, the ionic liquid, and water and organic solvents, if necessary, are finally mixed together.
  • the conductive cellulose composition has high conductivity and flexibility. In general, it is suitable if the dispersion containing an ionic liquid and cellulose or cellulose pulp, and water or an organic solvent as required, does not undergo phase separation for several hours, more preferably for several days. .
  • the ionic liquid and cellulose or cellulose pulp and, if necessary, water or an organic solvent are compatible with each other in order to achieve better dispersibility.
  • the term “compatible” refers to the property that two or more substances have an affinity for each other and form a solution or a mixture.
  • the method for producing a conductive cellulose composition of the present invention is based on the above findings, Step 1 of preparing a mixture of an ionic liquid and a conductive material, and dispersing the cellulose in the mixture Step 2 of preparing
  • the method for producing a conductive paper according to the present invention is based on the above knowledge. Step 1 of preparing a mixture of an ionic liquid and a conductive substance, and preparing a dispersion by dispersing cellulose in the mixture And a step 3 of drying the dispersion.
  • FIG. 2 is a flowchart showing a method for producing conductive paper according to an embodiment of the present invention.
  • the method for producing conductive paper of the present invention comprises a mixture preparation step S1 for preparing a mixture of a conductive substance and an ionic liquid, and a dispersion is prepared by dispersing cellulose in the obtained mixture. It includes a step of producing a conductive cellulose composition by the dispersion liquid preparation step S2, and further includes a drying step S3 of drying the obtained conductive cellulose composition to produce conductive paper.
  • the ionic liquid recovery step S4 for recovering the ionic liquid from the conductive paper is a step performed as necessary.
  • any conductive material that is miscible with cellulose can be used as described above. That is, carbon nanotubes, metal nanotubes, highly conductive polymers, and the like can be used.
  • the ionic liquid is also called a room temperature molten salt or simply a molten salt, and is a salt that exhibits a molten state in a wide temperature range including normal temperature.
  • conventionally known various ionic liquids can be used, and examples thereof include those described in Japanese Patent No. 3676337 and Japanese Patent No. 3880580.
  • both hydrophilic and hydrophobic ionic liquids can be used as the ionic liquid.
  • the hydrophilic ionic liquid include N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate (DEMEBF 4 ).
  • DEMEBF 4 N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate
  • hydrophobic ionic liquid examples include N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) imide (DEMETFSI), 1-ethyl-3-methylimidazolium tetra Fluoroborate (EMIBF 4 ), 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIPF 6 ), 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMITFSI), 1-butyl-3 - methylimidazolium tetrafluoroborate (BMIBF 4), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF 6), 1- butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ( MITFSI) can be mentioned.
  • DEMETFSI 1-ethyl-3
  • cellulose may be directly dispersed in the mixture obtained in the mixture preparation step S1, and a dispersion medium such as water or an organic solvent can be used as necessary.
  • a dispersion medium such as water or an organic solvent
  • a hydrophilic ionic liquid water can be used as a suitable dispersion medium.
  • a hydrophobic ionic liquid it is preferable to use a hydrophilic organic solvent.
  • useful hydrophilic organic solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, formic acid, acetic acid, acetone, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, and N, N-dimethylformamide.
  • a typical example is ethanol.
  • the organic solvent is not limited to the above, and a solvent that disperses and dissolves cellulose to be used can be appropriately selected and used. Specifically, toluene, xylene, carbon tetrachloride, or the like can be used.
  • the dispersion medium such as water and organic solvent mentioned above can be used not only in the dispersion preparation step S2 but also in the mixture preparation step S1 as necessary.
  • PEDOT which is a conductive polymer
  • dimethyl sulfoxide which is an organic solvent
  • the effect of remarkably improving the conductivity of PEDOT can be obtained.
  • the conductive cellulose composition of the present invention can be produced either in an organic solvent or in water.
  • the hydrophilicity and hydrophobicity of the conductive cellulose composition and the conductive paper are controlled by the combination of the ionic liquid used in the mixture preparation step S1 and the dispersion medium used in the dispersion preparation step S2 after adding cellulose. can do.
  • cellulose miscible with water and an ionic liquid miscible with water are used. That is, in the mixture preparation step S1, for example, DEMEBF 4 is used as an ionic liquid, and in the dispersion preparation step S2, a dispersion liquid containing a conductive substance, an ionic liquid, and cellulose mixed with water is used using water as a dispersion medium.
  • a dispersion liquid containing a conductive substance, an ionic liquid, and cellulose mixed with water is used using water as a dispersion medium.
  • a hydrophobic conductive cellulose composition and conductive paper when producing a hydrophobic conductive cellulose composition and conductive paper, a hydrophobic ionic liquid, an organic solvent mixed therewith, and a conductive material mixed with the organic solvent are used. That is, in the mixture preparation step S1, for example, DEMETFSI or BMIBF 4 is used, and in the dispersion preparation step S2, for example, ethanol is used as a dispersion medium to prepare a dispersion containing a conductive substance, an ionic liquid, and cellulose. In addition, a miscible combination is selected for the dispersion medium and cellulose. For example, microfibril cellulose can be dissolved in a polar solvent such as ethanol or methanol (the hydrophilic organic solvent described above), so that these combinations can be suitably used for the production of hydrophobic conductive paper.
  • a polar solvent such as ethanol or methanol (the hydrophilic organic solvent described above
  • the mixture preparation step S1 the above-described conductive substance and ionic liquid are prepared and mixed uniformly. Thereby, the mixture (gel composition) of an electroconductive substance and an ionic liquid is prepared.
  • a jet mill, a ball mill, an ultrasonic disperser, a mortar, an automatic mortar or the like can be used for mixing and dispersing each component.
  • conductive devices such as carbon nanotubes and conductive polymers are more uniformly dispersed in the gel composition, and from the viewpoint of avoiding cutting of the carbon nanotubes and lowering of the conductive polymer due to the mixing process. Selected. From the viewpoint of preventing the carbon nanotube from being cut, it is preferable to use a jet mill.
  • the method for producing a gel composition in which carbon nanotubes and an ionic liquid are mixed is not limited to this method, and is disclosed in Japanese Patent Nos. 3676337, 3880560, 3924273, and 2004-254881. Known methods described in Japanese Patent Laid-Open No. 2005-176428 and the like can also be used. Further, the present invention is not limited to the mixing / dispersing method using the apparatus described above or the method described in the above document, and any method can be used as long as it can uniformly mix and disperse the conductive substance and the ionic liquid. This method can be adopted.
  • the gel composition containing the conductive material and the ionic liquid obtained in the mixture preparation step S1 and cellulose are mixed and dispersed by adding water or an organic solvent as necessary. Let As a result, the conductive cellulose composition of the present invention in the form of a liquid, paste or gel dispersion is obtained.
  • the viscosity of the resulting dispersion can be adjusted by adding or removing water or an organic solvent. That is, the viscosity of the dispersion can be reduced by adding water or an organic solvent as appropriate to the gel composition or the dispersion before, during, or after the dispersion preparation step S2. Alternatively, before or during the dispersion preparation step S2, water or an organic solvent contained in the gel composition or the dispersion can be partially removed by evaporation or the like to increase the viscosity of the dispersion. .
  • a jet mill, a ball mill, an ultrasonic disperser, a mortar, an automatic mortar, or the like can also be used for mixing and dispersion in the dispersion preparation step S2, and among these, a jet mill that can prevent cutting of carbon nanotubes should be used.
  • a jet mill that can prevent cutting of carbon nanotubes should be used.
  • the present invention is not limited to the mixing / dispersing method using these apparatuses, and any method can be adopted as long as the conductive substance, the ionic liquid, and cellulose can be uniformly mixed and dispersed. it can.
  • a part of or all of the water and the organic solvent contained in the dispersion (conductive cellulose composition) obtained in the dispersion preparation step S2 is dried, heated, evacuated, and the like. Use to remove and solidify the conductive cellulose composition. Thereby, the conductive paper of the present invention is obtained.
  • the conductive paper of a desired shape in drying process S3 you may shape
  • a known method for molding a fluid paste or liquid composition can be used, and examples thereof include coating, printing, extrusion, casting, and injection.
  • the forming process of the conductive cellulose composition is not limited to being performed in a dispersion state. That is, after the conductive cellulose composition is solidified in the drying step S3, the obtained conductive paper may be machined into a desired shape. For example, the thickness of the conductive paper can be reduced by pressing or the like.
  • the conductive paper obtained in the drying step S3 can be used for the ionic liquid recovery step S4.
  • This ionic liquid recovery step S4 is a step that is performed as necessary, and removes the ionic liquid from the conductive paper using a Soxhlet method or the like.
  • the conductive paper which consists of an electroconductive substance and a cellulose is obtained.
  • the conductivity of the conductive paper from which the ionic liquid has been removed is lower than that of the conductive paper containing the ionic liquid.
  • the ionic liquid removed from the conductive paper can be recovered and reused in the mixture preparation step S1, as shown in FIG. Thereby, manufacturing cost can be reduced significantly.
  • the dried conductive paper is used for the ionic liquid recovery step S4, but the dispersion (conductive cellulose composition) obtained in the dispersion preparation step S2 is used for the ionic liquid recovery step S4. May be. Also in this case, the ionic liquid can be recovered from the conductive cellulose composition and reused.
  • the manufacturing process demonstrated above is an example of the manufacturing process for obtaining the electroconductive cellulose composition and conductive paper which concern on this invention, and is not limited to the said example. That is, some steps may be omitted or the order may be changed as necessary. Moreover, you may add another electroconductive substance, another cellulose, another solvent, and another ionic liquid in a suitable process as needed.
  • the conductive substance and the ionic liquid are uniformly obtained by using the ionic liquid in the mixture preparation step S1.
  • a mixed mixture (gel composition) can be obtained.
  • the bundles can be dispersed while being separated into individual carbon nanotubes by the action of the ionic liquid.
  • the conductive polymer can be uniformly dispersed in the ionic liquid having an affinity for the conductive polymer.
  • cellulose and an electroconductive substance are ionized by disperse
  • the ionic liquid recovery step S4 the ionic liquid can be recovered from the produced conductive paper or dispersion (conductive cellulose composition). And since the collect
  • the conductive paper of the present invention can be easily recycled.
  • the conductive paper produced through the drying step S3 or the ionic liquid recovery step S4 is dissolved in a liquid in the dissolving step S5, thereby dispersing the conductive cellulose uniformly dispersed (conductive cellulose composition). Thing).
  • dissolving conductive paper can be reproduce
  • the dissolution step S5 is a step in which used conductive paper is immersed in a dispersion medium such as water or an organic solvent and stirred.
  • the dispersion medium used in the dissolving step S5 is appropriately selected according to the hydrophilicity and hydrophobicity of the conductive paper to be dissolved. That is, water is used as a dispersion medium when dissolving hydrophilic conductive paper, and an organic solvent (dispersion medium other than water) is used as a dispersion medium when dissolving hydrophobic conductive paper.
  • the dispersion medium it is preferable to use the same dispersion medium as used in the dispersion liquid preparation step S2 when the conductive paper to be subjected to the dissolution step S5 is manufactured. In addition, you may add an ionic liquid to a dispersion medium as needed.
  • the conductive paper of the present invention can be recycled by a very simple process of dissolving in a dispersion medium.
  • metal is used for the conductive member, and recycling requires high energy such as heating, but by using the conductive paper of the present invention, high energy such as heat is not given.
  • An electronic device that can be easily recycled can be formed.
  • FIG. 3 is a diagram illustrating an example of a process for producing conductive paper using carbon nanotubes as a conductive substance.
  • Step1, Step2, and Step3 correspond to the mixture preparation step S1, the dispersion preparation step S2, and the drying step S3, respectively, in the conductive paper manufacturing method of the present invention.
  • single-walled carbon nanotubes (purity> 99.98%, length less than 1 mm, diameter 3 nm) produced by the super-growth (SG) method were used as the carbon nanotubes that are conductive materials.
  • Such carbon nanotubes are obtained, for example, by peeling an aligned aggregate of carbon nanotubes grown from a substrate by using the method described in WO2006 / 011655 from the growth substrate.
  • N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate (DEMEBF 4 ) was used as the ionic liquid.
  • Step 1 mixture preparation step S1
  • 50 mg of the above single-walled carbon nanotubes were added to N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, which is a hydrophilic ionic liquid.
  • DEMEBF 4 N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate
  • Step 2 (dispersion liquid preparation step S2), 150 mg of the carbon nanotube dispersion gel obtained in Step 1 is mixed with 10 ml of deionized water as a dispersion medium, microfibril cellulose (Celish manufactured by Daicel Chemical Industries, 10% cellulose) 200 mg of an aqueous liquid containing the solution was sequentially added. The resulting mixture was then stirred with a stirrer at 25 ° C. for 1 hour, and then sonicated with SMT UH-50 at 30 ° C. for 10 minutes. As a result, a conductive cellulose composition (nanotube-dispersed aqueous solution) in which single-walled carbon nanotubes, an ionic liquid, and microfibril cellulose were uniformly dispersed was obtained.
  • a conductive cellulose composition nanotube-dispersed aqueous solution in which single-walled carbon nanotubes, an ionic liquid, and microfibril cellulose were uniformly dispersed was obtained.
  • Step 3 drying step S3
  • the nanotube-dispersed aqueous solution obtained in Step 2 was drop-cast on a polytetrafluoroethylene (PTFE) plate and air-dried over 24 hours.
  • PTFE polytetrafluoroethylene
  • FIG. 4 is a diagram illustrating an example of a process for producing conductive paper using PEDOT as a conductive substance.
  • Step1, Step2, and Step3 correspond to the mixture preparation step S1, the dispersion preparation step S2, and the drying step S3, respectively, in the conductive paper manufacturing method of the present invention.
  • PEDOT a highly conductive polymer obtained by polymerizing 3,4-ethylenedioxythiophene in a high molecular weight polystyrenesulfonic acid aqueous solution (manufactured by TA Chemical Co., Ltd.). Baytron PH500, PEDOT content 1 wt%) was used.
  • the ionic liquid N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate (DEMEBF 4 ) was used.
  • DEMEBF 4 dimethyl sulfoxide
  • DMSO dimethyl sulfoxide
  • Step 1 mixture preparation step S1
  • 4 g of PEDOT 1% aqueous solution 40 mg of PEDOT
  • 50 mg of hydrophilic ionic liquid DEMEBF 4
  • DMSO dimethyl sulfoxide
  • Step 2 (dispersion preparation step S2), 10 ml of deionized water as a dispersion medium and 100 mg of microfibril cellulose were sequentially added to the PEDOT-PSS gel obtained in Step 1. The resulting mixture was then stirred at 25 ° C. for 1 hour. As a result, a conductive cellulose composition (PEDOT-PSS gel-dispersed aqueous solution) in which PEDOT, an ionic liquid, and microfibril cellulose were uniformly dispersed was obtained.
  • PEDOT-PSS gel-dispersed aqueous solution in which PEDOT, an ionic liquid, and microfibril cellulose were uniformly dispersed was obtained.
  • Step 3 drying step S3
  • the PEDOT-PSS gel-dispersed aqueous solution was poured onto a PTFE plate by drop casting and air-dried over 24 hours.
  • conductive paper PEDOT-PSS conductive paper
  • PEDOT-PSS highly conductive polymer
  • FIG. 5 is a graph showing the relationship between cellulose content and electrical conductivity.
  • FIG. 6 is a planar SEM photograph of carbon nanotube conductive paper and PEDOT-PSS conductive paper.
  • the maximum conductivity (72 S / cm) was obtained when the cellulose content was 12 wt% and the mixing ratio of SWNT and DENEBF 4 was 1: 2. To the best of the inventors' knowledge, this is the highest reported soft material (paper or polymer), and previously reported non-insulating paper (eg Yoon SH, Jin HJ, Kook MC, Pyun YR (2006) Electrically conductive bacterial cellulose by incorporation of carbon nanotubes, Biomacromolecules 7: 1280-1284), which is about three orders of magnitude larger than the conductivity (about 0.1 S / cm).
  • single-walled carbon nanotubes have strong covalent bonds and tend to form bundles, they tend to aggregate when mixed with polymers and other materials.
  • the ionic liquid used in the present invention can prevent entanglement of single-walled carbon nanotubes.
  • the content of the single-walled carbon nanotubes can be as large as 30 wt% without adversely affecting the softness of the paper, and the high-aspect ratio super-growth carbon nanotubes can be uniformly dispersed in the microfibril cellulose. I was able to. As a result, a large electrical conductivity was realized as described above.
  • PEDOT-PSS conductive paper As shown in FIG. 6, the surface became rough as the cellulose content increased.
  • a thick and porous PEDOT-PSS conductive paper was obtained.
  • a brittle PEDOT-PSS conductive paper was obtained.
  • the maximum conductivity (75 S / cm) was obtained when the cellulose content was 10 wt% and the mixing ratio of PEDOT and DENEBF 4 was 4: 5.
  • PEDOT-PSS conductive paper not only had high electrical conductivity, but also excellent flexibility and softness.
  • FIG. 7 is a graph showing a change in resistance value with respect to a bending radius when the carbon nanotube conductive paper and the PEDOT-PSS conductive paper produced in this example are bent. The measurement was performed by bending the conductive paper using a stress device equipped with an accurate mechanical stage and measuring the resistance value after bending.
  • the resistance value when bent is almost constant, and the fluctuation range of the resistance value is completely bent (the bending radius is 100 ⁇ m). Is less than negligible. From this, it was confirmed that the conductive paper of the present invention has great mechanical flexibility and is excellent in durability under bending stress.
  • a stress acts on the interface between the metal thin film and the paper / plastic, and the metal thin film is easily broken.
  • the conductive cellulose is entangled with each other to form the conductive paper, so that both high electrical conductivity and high mechanical flexibility / durability can be realized at the same time.
  • the PEDOT-PSS conductive paper of this embodiment can be bent completely and has properties that are significantly different from those of conventional PEDOT films. This is considered to be because the mixture of the ionic liquid and PEDOT formed a gel and could be uniformly dispersed in the microfibril cellulose.
  • FIG. 8 is a graph showing the results of measuring the transmission characteristics of the carbon nanotube conductive paper and PEDOT-PSS conductive paper prepared in this example. Measurement results for copper wiring are also shown for comparison. The measurement was performed using a network analyzer (Agilent 4395A). The length, width, and thickness of the carbon nanotube conductive paper and PEDOT-PSS conductive paper used for the measurement were 30 mm, 5 mm, and 70 ⁇ m, respectively.
  • the transmission loss of the carbon nanotube conductive paper and the PEDOT-PSS conductive paper was within ⁇ 2 dB up to 100 MHz. Even when compared with the transmission loss of the copper wiring, the difference was less than 37%.
  • Another important advantage of the conductive paper of the present invention is that the current flowing through the paper is dependent on electrons rather than ions. As a result, excellent electrical characteristics can be realized in the MHz region as shown.
  • FIG. 9 is a graph showing electrical characteristics of the carbon nanotube conductive paper and the PEDOT-PSS conductive paper.
  • FIG. 9A is a graph showing transmission characteristics
  • FIG. 9B is a graph showing the relationship between temperature and conductivity.
  • the maximum power that can be transmitted through the carbon nanotube conductive paper was 35 W
  • the maximum power that could be transmitted through the PEDOT-PSS conductive paper was 38 W.
  • Transmission characteristics were measured using a 13.56 MHz power generator (ULGN RGN-1302) and a spectrum analyzer (Agilent 4395A) for measuring the transmitted power.
  • FIG. 9B although there are variations, both the carbon nanotube conductive paper and the PEDOT-PSS conductive paper retain excellent conductivity even after being heated to 300 ° C. Also confirmed to be excellent.
  • Both the carbon nanotube conductive paper and the PEDOT-PSS conductive paper can be recycled using water.
  • these conductive papers are immersed in water, hydrogen bonds between the conductive celluloses are weakened by water.
  • the conductive cellulose forming the paper rapidly dissolves in water and returns to the dispersion in which the conductive cellulose is dispersed. Thereafter, by drying the obtained dispersion, conductive paper can be formed without additional steps such as purification. Such regeneration of the conductive paper can be performed in exactly the same manner for a circuit pattern formed by printing.
  • FIG. 10 is a graph showing the change in conductivity when the carbon nanotube conductive paper and PEDOT-PSS conductive paper produced in this example are recycled.
  • FIG. 11 is a planar SEM photograph of carbon nanotube conductive paper and PEDOT-PSS conductive paper after recycling.
  • carbon nanotube conductive paper and PEDOT-PSS conductive paper are stirred in water at 30 ° C. for 1 hour to dissolve these conductive papers to obtain a carbon nanotube dispersed aqueous solution and a PEDOT-PSS dispersed gel aqueous solution.
  • the obtained dispersion is again poured onto the PTFE plate by drop casting, air-dried for 24 hours, and regenerated as carbon nanotube conductive paper and PEDOT-PSS conductive paper, respectively.
  • the above process was set as one cycle, and 10 times of recycling was performed as shown in FIG. 10, and the conductivity was measured every time it was recycled.
  • the conductive paper becomes hydrophilic when made using a hydrophilic ionic liquid, and becomes hydrophobic when a hydrophobic ionic liquid is used instead of the hydrophilic ionic liquid.
  • hydrophobic conductive paper in the previous manufacturing process of carbon nanotube conductive paper, DEMETFSI was used as the hydrophobic ionic liquid, and ethanol was used to disperse the carbon nanotube dispersion gel.
  • a carbon nanotube conductive paper was prepared. The ratio of the content of the single-walled carbon nanotube and the ionic liquid (DEMETFSI) in the hydrophobic carbon nanotube conductive paper was 1: 1.
  • a hydrophobic PEDOT-PSS conductive paper was prepared using DEMETFSI as a hydrophobic ionic liquid and ethanol as a dispersion medium in the previous manufacturing process of PEDOT-PSS conductive paper.
  • FIG. 12 (a) is a graph comparing the change in conductivity with respect to the cellulose content for hydrophilic carbon nanotube conductive paper and hydrophobic carbon nanotube conductive paper.
  • FIG. 12 (b) is a graph comparing the change in conductivity with respect to the cellulose content for hydrophilic PEDOT-PSS conductive paper and hydrophobic PEDOT-PSS conductive paper.
  • FIG. 13 is a graph showing changes in resistance values when the hydrophilic and hydrophobic carbon nanotube conductive paper and the hydrophilic and hydrophobic carbon nanotube conductive paper are immersed in water, respectively.
  • the resistance value of the hydrophobic carbon nanotube conductive paper did not change even when immersed in water.
  • the resistance value of the hydrophilic carbon nanotube conductive paper starts to increase immediately after immersion. This is because the hydrophilic carbon nanotube conductive paper begins to dissolve in water within a few seconds.
  • FIG. 14 shows a carbon nanotube conductive paper (indicated as “SG” in the figure) using a single-walled carbon nanotube produced by a super-growth method as a conductive substance, and a single-walled carbon nanotube produced by a commercially available HiPco method. It is a figure which shows the comparison with the used carbon nanotube conductive paper (it shows as "HiPco” in a figure).
  • the carbon nanotube conductive paper (SG) using single-walled carbon nanotubes by the super-growth method has a much larger conductive property than the carbon nanotube conductive paper (HiPco) using single-walled carbon nanotubes by the HiPco method. Showed the rate.
  • the carbon nanotube conductive paper using single-walled carbon nanotubes by a commercially available HiPco method as the conductive material has a conductivity of 5.7 S / cm, which is sufficiently higher than that of conventionally known conductive paper.
  • the conductive paper using the single-walled carbon nanotubes by the super-growth method further obtained a conductivity of 10 times or more. It can be seen that a large aspect ratio of single-walled carbon nanotubes by the super-growth method is important in obtaining a large electrical conductivity.
  • the surface of the conductive paper using single-walled carbon nanotubes by the super-growth method was much smoother than the surface of the conductive paper using single-walled carbon nanotubes by the HiPco method. This means that single-walled carbon nanotubes obtained by the super-growth method can be uniformly dispersed in cellulose.
  • FIG. 15A is a photograph of a touch sensor made of only paper including 8 ⁇ 8 conductive paper capacitors connected in the vertical and horizontal directions by paper wiring.
  • FIG. 15B is a circuit diagram of the touch sensor.
  • FIG. 16A is a schematic diagram of 2 ⁇ 2 cells of the touch sensor shown in FIG.
  • FIG. 16B is an explanatory diagram showing the change in the capacity of the cell of the touch sensor as a function of time.
  • the touch sensor 100 includes a conductive paper wiring 102 extending vertically and horizontally, and a conductive paper capacitor 101 (size: 5 ⁇ 5 mm) formed corresponding to the intersection of the conductive paper wiring 102. 2 ).
  • a plurality of conductive paper capacitors 101 arranged in a matrix form individual cells of the touch sensor 100.
  • the touch sensor 100 has a configuration in which conductive paper patterns 105 are formed on both surfaces of an insulating paper 103 having a thickness of 15 ⁇ m.
  • the conductive paper pattern 105 formed on the upper surface of the insulating paper 103 has a rectangular electrode 101a and a conductive paper wiring (bit line) 102a.
  • the conductive paper pattern 105 formed on the lower surface of the insulating paper 103 has a rectangular electrode 101b and a conductive paper wiring 102b (word line).
  • the electrode 101a and the electrode 101b arranged to face each other and the insulating paper 103 sandwiched therebetween constitute the conductive paper capacitor 101.
  • FIG. 16 (b) Changes from 45 pF to 150 pF, for example. Thereby, the position touched by the finger on the touch sensor 100 can be detected.
  • the response time of the touch sensor 100 is less than 100 milliseconds, and this high sensitivity and high-speed response can be realized by fully utilizing the large conductivity of the conductive paper of the present invention.
  • a conductive paper and a conductive cellulose composition having sufficient conductivity and elasticity can be provided.
  • These conductive paper and conductive cellulose composition can be suitably used for conductive members of various articles, and can be particularly suitably used for electronic devices.
  • the conductive paper of the present invention can be easily recycled in the same way as ordinary paper, and has extremely great advantages not only from the viewpoint of resource saving and environmental protection, but also from the viewpoint of the efficiency of creating electrical and electronic circuits. It is what brings.

Abstract

A conductive paper and conductive cellulose composition are characterized by being a mixture of cellulose and conductive material. This conductive paper and the conductive cellulose composition have high conductivity, are particularly suitable for use in electronic devices and can be dissolved in liquids and easily recycled in the same way as ordinary paper.

Description

導電紙とその製造方法、導電性セルロース組成物とその製造方法、物品、電子デバイスConductive paper and manufacturing method thereof, conductive cellulose composition and manufacturing method thereof, article, electronic device
　本発明は、導電紙とその製造方法、導電性セルロース組成物とその製造方法、物品、及び電子デバイスに関する。 The present invention relates to a conductive paper and a manufacturing method thereof, a conductive cellulose composition and a manufacturing method thereof, an article, and an electronic device.
　紙は、水の付加および／または除去によってセルロースからなる植物繊維間の水素結合を制御できるため、リサイクルするのに理想的である。将来において持続可能な社会を実現するには、産業が変化し、紙のようにリサイクル可能な天然材料を用いる必要がある。エレクトロニクスも例外であってはならない。しかし、植物繊維はそもそも非導電性であるため、紙の電子的な用途はこれまで非常に限られていた。
　例えば、下記特許文献１には、導電性高分子を内添した紙パルプを抄紙して導電性高分子複合紙を得ることが提案されている。
特開２０００－１６０５００号公報 Paper is ideal for recycling because hydrogen addition and / or removal of water can control hydrogen bonding between cellulose plant fibers. To realize a sustainable society in the future, the industry will change and it will be necessary to use recyclable natural materials such as paper. Electronics should not be an exception. However, since plant fibers are non-conductive in the first place, the electronic use of paper has been very limited so far.
For example, Patent Document 1 below proposes that a paper sheet made of paper containing a conductive polymer is made to obtain a conductive polymer composite paper.
JP 2000-160500 A
　しかし、同公報の図１からもわかるように、この紙は高々１Ｓ／ｃｍ程度の導電率しか示さず、電気・電子的な用途に用いるには導電性があまりにも不十分なものであった。
　本発明は、上記事情に鑑みて成されたものであって、電子デバイスにも十分適用できる優れた導電性を備えた導電紙、及び導電性セルロース組成物と、それらの製造方法を提供することを目的とする。 However, as can be seen from FIG. 1 of the same publication, this paper exhibits only a conductivity of about 1 S / cm at most, and the conductivity is too insufficient to be used for electrical and electronic applications. .
The present invention has been made in view of the above circumstances, and provides a conductive paper having excellent conductivity that can be sufficiently applied to an electronic device, a conductive cellulose composition, and a method for producing the same. With the goal.
　本発明の導電紙は、セルロースと導電性物質とが混和していることを特徴とする。
　この導電紙は、セルロースと導電性物質とが互いに絡み合って相互に均一に分散した構造を有する。本発明の導電紙によれば、セルロースと導電性物質との混和物である導電性セルロースが絡み合って固体を構成しているため、内部に導電性物質のネットワークが形成され、良好な導電性を呈する。
　セルロースと導電性物質の混和の程度は、これらの混和物を分散媒に分散させたときに相分離しない程度であればよい。さらにセルロースと導電性物質とが相互に分離不可能な程度に混合されていると、より良好な導電性が得られ、またリサイクル性にも優れた導電紙となる。 The conductive paper of the present invention is characterized in that cellulose and a conductive substance are mixed.
This conductive paper has a structure in which cellulose and a conductive substance are entangled with each other and uniformly dispersed. According to the conductive paper of the present invention, conductive cellulose, which is a mixture of cellulose and a conductive substance, is intertwined to form a solid, so that a network of conductive substances is formed inside, and good conductivity is achieved. Present.
The degree of mixing of the cellulose and the conductive material may be such that the phase separation does not occur when these admixtures are dispersed in the dispersion medium. Furthermore, when cellulose and a conductive substance are mixed to such an extent that they cannot be separated from each other, a better conductive property can be obtained and a conductive paper excellent in recyclability can be obtained.
　上記導電紙は、イオン液体を含むものであってもよい。本発明の導電紙は、その製造工程にイオン液体を用いる。イオン液体を含んでいる場合、より良好な導電率が得られる。また、液体成分であるため、カーボンナノチューブや導電性ポリマーなどの硬いものが多い導電性物質の添加による硬化を抑えることができ、柔らかく質感に優れた導電紙とすることができる。すなわち、イオン液体は導電紙の可塑剤としても作用する。 The conductive paper may contain an ionic liquid. The conductive paper of the present invention uses an ionic liquid in its production process. When the ionic liquid is contained, better conductivity can be obtained. Further, since it is a liquid component, curing due to the addition of a conductive material that is often hard such as carbon nanotubes or a conductive polymer can be suppressed, and a conductive paper that is soft and excellent in texture can be obtained. That is, the ionic liquid also acts as a plasticizer for conductive paper.
　上記導電紙は、液体に溶かして再生可能である。すなわち本発明の導電紙は、通常の紙と同様に極めて容易にリサイクルすることが可能である。 The conductive paper can be regenerated by dissolving it in a liquid. That is, the conductive paper of the present invention can be recycled very easily as with normal paper.
　上記導電紙は、導電率が１Ｓ／ｃｍ以上であることが好ましい。本発明の導電紙における導電率に制限はないが、１Ｓ／ｃｍ以上であれば、導電性部材として好適に用いることができる。さらに、導電率は５０Ｓ／ｃｍ以上であることが好ましく、この程度の導電率があれば電子デバイスの配線等に好適に用いることができる。 The conductive paper preferably has a conductivity of 1 S / cm or more. Although there is no restriction | limiting in the electrical conductivity in the conductive paper of this invention, if it is 1 S / cm or more, it can use suitably as a conductive member. Furthermore, the electrical conductivity is preferably 50 S / cm or more, and if there is such an electrical conductivity, it can be suitably used for wiring of electronic devices.
　上記導電紙は、導電性物質がカーボンナノチューブであることが好ましく、カーボンナノチューブの長さが１μｍ以上１０ｃｍ以下であることがより好ましい。
　また上記導電紙は、導電性物質が導電性ポリマーであることも好ましい。
　本発明の導電紙を構成する導電性物質として、カーボンナノチューブ又は導電性ポリマーを用いることで、優れた導電率を有する導電紙を構成することができる。 In the conductive paper, the conductive substance is preferably a carbon nanotube, and the length of the carbon nanotube is more preferably 1 μm or more and 10 cm or less.
In the conductive paper, the conductive substance is preferably a conductive polymer.
By using a carbon nanotube or a conductive polymer as a conductive substance constituting the conductive paper of the present invention, a conductive paper having excellent conductivity can be configured.
　上記導電紙は、イオン液体が親水性である構成とすることもできる。この構成によれば、親水性の導電紙が得られる。また、イオン液体が疎水性である構成とすれば、疎水性の導電紙を得ることができる。 The conductive paper may be configured such that the ionic liquid is hydrophilic. According to this configuration, hydrophilic conductive paper can be obtained. Further, if the ionic liquid is configured to be hydrophobic, hydrophobic conductive paper can be obtained.
　上記導電紙では、他の導電性物質が混在していることも好ましい。この構成によれば、さらに導電性を向上させたり、機械的特性を向上させることもできる。上記他の導電性物質としては、例えば金属や導電性ポリマーを用いることができる。 It is also preferable that other conductive materials are mixed in the conductive paper. According to this configuration, the electrical conductivity can be further improved and the mechanical characteristics can be improved. As said other electroconductive substance, a metal and a conductive polymer can be used, for example.
　次に、本発明の導電性セルロース組成物は、セルロースと導電性物質とが混和していることを特徴とする。この構成によれば、導電紙の構成材料として、あるいは導電性を有する液体材料として好適な導電性セルロース組成物を提供することができる。セルロースと導電性物質とが混和していることで、これらの混和物である導電性セルロースは分散媒に均一に分散して相分離しない分散液となる。 Next, the conductive cellulose composition of the present invention is characterized in that cellulose and a conductive substance are mixed. According to this configuration, it is possible to provide a conductive cellulose composition suitable as a constituent material of conductive paper or as a liquid material having conductivity. By mixing the cellulose and the conductive material, the conductive cellulose, which is a mixture of these, becomes a dispersion liquid that is uniformly dispersed in the dispersion medium and does not phase-separate.
　上記導電性セルロース組成物は、イオン液体を含んでいてもよい。イオン液体を含む場合、イオン液体が導電性物質とセルロースの双方に親和性を示すため、導電性物質とセルロースとがより均一に相互に分散した導電性セルロース組成物となる。導電性セルロース組成物の製造工程ではイオン液体が用いられるため、通常は、導電性セルロース組成物はイオン液体を含むものとなる。 The conductive cellulose composition may contain an ionic liquid. When the ionic liquid is included, the ionic liquid exhibits affinity for both the conductive material and cellulose, and thus the conductive cellulose composition in which the conductive material and cellulose are more uniformly dispersed is obtained. Since an ionic liquid is used in the process for producing a conductive cellulose composition, the conductive cellulose composition usually contains an ionic liquid.
　上記導電性セルロース組成物は、他の導電性物質が混在していてもよい。この構成によれば、他の導電性物質によってさらに導電性セルロース組成物に機能性を付与することができる。 The conductive cellulose composition may contain other conductive substances. According to this configuration, functionality can be further imparted to the conductive cellulose composition by another conductive substance.
　上記導電性セルロース組成物は、ペースト状、又はゲル状、又は液状であることが好ましい。このような液体組成物とすることで、スクリーン印刷、インクジェット印刷、ディスペンサーなどを含むあらゆる印刷機のインク（液体材料）として用いて所定のパターンに印刷することができる導電性セルロース組成物となる。 The conductive cellulose composition is preferably pasty, gelled, or liquid. By setting it as such a liquid composition, it becomes an electroconductive cellulose composition which can be used as an ink (liquid material) of all the printing machines including screen printing, inkjet printing, a dispenser etc., and can be printed on a predetermined pattern.
　本発明の物品は、本発明の導電紙、又は本発明の導電性セルロース組成物を備える。
　また本発明の電子デバイスは、本発明の導電紙、又は本発明の導電性セルロース組成物を備える。 The article of the present invention comprises the conductive paper of the present invention or the conductive cellulose composition of the present invention.
Moreover, the electronic device of the present invention includes the conductive paper of the present invention or the conductive cellulose composition of the present invention.
　本発明の導電紙の製造方法は、イオン液体と導電性物質との混合物を調製する工程１と、前記混合物にセルロースを分散させて分散液を調製する工程２と、前記分散液を乾燥させる工程３と、を有する。
　この製造方法によれば、イオン液体の作用により導電性物質とイオン液体とが均一に分散した混合物を得ることができ、さらにこの混合物にセルロースを加えたときにも、イオン液体の作用によってセルロースと導電性物質とイオン液体とが均一に分散した分散液を得ることができる。これにより、セルロースと導電性物質とが混和した導電性セルロースを含む分散液を得ることができる。そして、分散液を乾燥させることで、導電性セルロースを有する導電紙を製造することができる。 The conductive paper manufacturing method of the present invention includes a step 1 for preparing a mixture of an ionic liquid and a conductive substance, a step 2 for preparing a dispersion by dispersing cellulose in the mixture, and a step for drying the dispersion. 3.
According to this manufacturing method, it is possible to obtain a mixture in which the conductive substance and the ionic liquid are uniformly dispersed by the action of the ionic liquid, and when cellulose is added to the mixture, the cellulose and A dispersion in which the conductive substance and the ionic liquid are uniformly dispersed can be obtained. Thereby, the dispersion liquid containing the electroconductive cellulose with which the cellulose and the electroconductive substance were mixed can be obtained. And the electrically conductive paper which has electroconductive cellulose can be manufactured by drying a dispersion liquid.
　上記導電紙の製造方法は、前記分散液の乾燥物から、前記イオン液体を除去する工程４、をさらに有していてもよい。この製造方法によれば、導電紙からイオン液体を除去し、回収することができる。そして、回収したイオン液体は再利用できるため、導電紙の製造コストを大幅に低減することができる。 The method for producing conductive paper may further include a step 4 of removing the ionic liquid from the dried product of the dispersion. According to this manufacturing method, the ionic liquid can be removed from the conductive paper and recovered. And since the collect | recovered ionic liquid can be reused, the manufacturing cost of conductive paper can be reduced significantly.
　上記導電紙の製造方法では、前記イオン液体が親水性である場合に、前記分散液を調製する工程で分散媒として水を添加することが好ましい。この製造方法によれば、導電性物質とセルロースとが均一に分散された導電性セルロースを有する親水性の導電紙を製造することができる。 In the method for producing conductive paper, when the ionic liquid is hydrophilic, it is preferable to add water as a dispersion medium in the step of preparing the dispersion. According to this manufacturing method, it is possible to manufacture hydrophilic conductive paper having conductive cellulose in which a conductive substance and cellulose are uniformly dispersed.
　上記導電紙の製造方法では、前記イオン液体が疎水性である場合に、前記分散液を調製する工程で水以外の分散媒を添加することが好ましい。この製造方法によれば、導電性物質とセルロースとが均一に分散された導電性セルロースを有する疎水性の導電紙を製造することができる。水以外の分散媒としては、例えばエタノールやメタノールなどの親水性有機溶剤を用いることができ、セルロースの種類に応じて適宜変更してもよい。 In the method for producing conductive paper, when the ionic liquid is hydrophobic, it is preferable to add a dispersion medium other than water in the step of preparing the dispersion. According to this manufacturing method, it is possible to manufacture a hydrophobic conductive paper having conductive cellulose in which a conductive substance and cellulose are uniformly dispersed. As the dispersion medium other than water, for example, a hydrophilic organic solvent such as ethanol or methanol can be used, and may be appropriately changed according to the type of cellulose.
　本発明の導電性セルロース組成物の製造方法は、イオン液体と導電性物質との混合物を調製する工程１と、前記混合物にセルロースを分散させて分散液を調製する工程２と、を有することを特徴とする。この製造方法によれば、導電性物質とセルロースとが混和した導電性セルロースが分散された分散液としての導電性セルロース組成物を製造することができる。 The method for producing a conductive cellulose composition of the present invention includes a step 1 for preparing a mixture of an ionic liquid and a conductive substance, and a step 2 for preparing a dispersion by dispersing cellulose in the mixture. Features. According to this production method, it is possible to produce a conductive cellulose composition as a dispersion in which conductive cellulose in which a conductive substance and cellulose are mixed is dispersed.
　本発明によれば、セルロースと導電性物質を混和させたことで、高い導電率と大きな機械的可撓性、耐久性を得られる導電紙を提供することができる。また本発明の導電紙は、容易にリサイクル可能である。
　また本発明によれば、導電性紙の高い導電率を利用した物品及び電子デバイスを提供することができる。
　本発明の製造方法によれば、高い導電率を有する導電紙及び導電性セルロース組成物を容易に製造することができる。 ADVANTAGE OF THE INVENTION According to this invention, the electrically conductive paper which can acquire high electrical conductivity, big mechanical flexibility, and durability can be provided by mixing cellulose and an electroconductive substance. The conductive paper of the present invention can be easily recycled.
Moreover, according to this invention, the articles | goods and electronic device using the high electrical conductivity of conductive paper can be provided.
According to the production method of the present invention, a conductive paper and a conductive cellulose composition having high conductivity can be easily produced.
導電性セルロース組成物を示す図。The figure which shows a conductive cellulose composition. 導電紙の製造方法を示すフロー図。The flowchart which shows the manufacturing method of conductive paper. カーボンナノチューブを用いた導電紙の製造プロセスの一例を示す図。The figure which shows an example of the manufacturing process of the electrically conductive paper using a carbon nanotube. ＰＥＤＯＴを用いた導電紙の製造プロセスの一例を示す図。The figure which shows an example of the manufacturing process of the electrically conductive paper using PEDOT. セルロース含有量と導電率の関係を示すグラフ。The graph which shows the relationship between cellulose content and electrical conductivity. カーボンナノチューブ導電紙とＰＥＤＯＴ－ＰＳＳ導電紙の平面ＳＥＭ写真。Plane SEM photograph of carbon nanotube conductive paper and PEDOT-PSS conductive paper. 曲げ半径に対する抵抗値の変化を示すグラフ。The graph which shows the change of the resistance value with respect to a bending radius. 導電紙の伝送特性を測定した結果を示すグラフ。The graph which shows the result of having measured the transmission characteristic of conductive paper. 導電紙の電気的特性を示すグラフ。The graph which shows the electrical property of conductive paper. 導電紙をリサイクルしたときの導電率の変化を示したグラフ。A graph showing a change in conductivity when conductive paper is recycled. リサイクル後のカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙の平面ＳＥＭ写真。Plane SEM photograph of carbon nanotube conductive paper and PEDOT-PSS conductive paper after recycling. 親水性と疎水性の導電紙におけるセルロース含有量と導電率の関係を示すグラフ。The graph which shows the relationship between the cellulose content and electrical conductivity in hydrophilic and hydrophobic conductive paper. 親水性と疎水性の導電紙における水中に浸したときの抵抗率の変化を示すグラフ。The graph which shows the change of the resistivity when immersed in water in hydrophilic and hydrophobic conductive paper. カーボンナノチューブの種類による導電率の差異を示すグラフ。The graph which shows the difference in the electrical conductivity by the kind of carbon nanotube. 電子デバイスの一例としてのタッチセンサの説明図。Explanatory drawing of the touch sensor as an example of an electronic device. 電子デバイスの一例としてのタッチセンサの説明図。Explanatory drawing of the touch sensor as an example of an electronic device.
符号の説明Explanation of symbols
　１０　導電性セルロース、１１　セルロース繊維、１２　カーボンナノチューブ、１００　タッチセンサ、１０１　導電紙キャパシタ、１０２　導電紙配線、１０３　絶縁紙 10 conductive cellulose, 11 cellulose fibers, 12 carbon nanotubes, 100 touch sensor, 101 conductive paper capacitor, 102 conductive paper wiring, 103 insulating paper
　以下に本発明の好ましい実施の形態を説明するが、本発明はこれらの形態のみに限定されるものではなく、本発明の技術思想の範囲内において様々な変形が可能である。 Hereinafter, preferred embodiments of the present invention will be described. However, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the technical idea of the present invention.
　（導電性セルロース組成物及び導電紙）
　本発明の導電性セルロース組成物は、セルロースと導電性物質とが混和した導電性セルロースを有するものであり、場合によっては、導電性セルロースに吸蔵されたイオン液体を含むものである。そして、本発明の導電性セルロース組成物は、イオン液体の有無、水や有機溶剤等の分散媒の有無や特性に応じて、例えば、液体状、ゲル状、固体状、紙状などの種々の形態を採りうる。 (Conductive cellulose composition and conductive paper)
The conductive cellulose composition of the present invention has a conductive cellulose in which cellulose and a conductive substance are mixed, and in some cases includes an ionic liquid occluded in the conductive cellulose. The conductive cellulose composition of the present invention can be used in various forms such as liquid, gel, solid, paper, etc., depending on the presence or absence of an ionic liquid, the presence or absence of a dispersion medium such as water or an organic solvent, and characteristics. Can take form.
　図１（ａ）は、本発明に係る導電性セルロース組成物を示す模式図であり、図１（ｂ）は、図１（ａ）に示す繊維を拡大して示す模式図である。
　図１（ａ）に示すように、本発明に係る導電性セルロース組成物は、多数の導電性セルロース１０を含む。個々の導電性セルロース１０は、図１（ｂ）に示すように、セルロース繊維１１の周囲に導電性物質であるカーボンナノチューブ１２が多数絡みついた構造を有している。
　セルロース繊維１１とカーボンナノチューブ１２は、繊維同士が複雑に絡み合い、水や有機溶剤などの分散媒に導電性セルロース１０を分散させてもセルロース繊維１１とカーボンナノチューブ１２とが相分離しない程度にまで混ざり合っている。このような状態を、本発明ではセルロースと導電性物質とが「混和した」状態と定義している。なお、混和しているセルロース繊維１１とカーボンナノチューブ１２とは、これらを損傷することなく分離することは不可能であり、分離不可能に混ざり合った状態ということもできる。
　なお、図１に示す導電性セルロース１０は、本発明に係る導電性セルロース組成物の一例を示したものであり、詳細は後述するが、導電性物質はカーボンナノチューブ１２に限定されるものではなく、例えば金属ナノチューブや導電性ポリマーを用いることもできる。 Fig.1 (a) is a schematic diagram which shows the electroconductive cellulose composition which concerns on this invention, FIG.1 (b) is a schematic diagram which expands and shows the fiber shown to Fig.1 (a).
As shown in FIG. 1A, the conductive cellulose composition according to the present invention includes a large number of conductive celluloses 10. As shown in FIG. 1B, each conductive cellulose 10 has a structure in which a large number of carbon nanotubes 12 that are conductive materials are entangled around a cellulose fiber 11.
The cellulose fibers 11 and the carbon nanotubes 12 are mixed to such an extent that the fibers are intertwined in a complicated manner and the cellulose fibers 11 and the carbon nanotubes 12 are not phase-separated even when the conductive cellulose 10 is dispersed in a dispersion medium such as water or an organic solvent. Matching. In the present invention, such a state is defined as a state in which cellulose and a conductive substance are “mixed”. In addition, it is impossible to separate the cellulose fibers 11 and the carbon nanotubes 12 that are mixed without damaging them, and it can be said that they are in a state of being mixed so as not to be separated.
The conductive cellulose 10 shown in FIG. 1 is an example of the conductive cellulose composition according to the present invention, and details will be described later, but the conductive material is not limited to the carbon nanotubes 12. For example, a metal nanotube or a conductive polymer can be used.
　本発明の導電性セルロース組成物の代表的な形態は、導電性セルロース１０の分散液をシート状に成形して乾燥させた導電紙である。本発明に係る導電紙は、母材のセルロースの特性、形態を損なうことなく、紙としての機能を所有しつつ、同時に導電性物質から付与される高い導電性をも兼ね備えている。 A representative form of the conductive cellulose composition of the present invention is conductive paper obtained by forming a dispersion of conductive cellulose 10 into a sheet and drying it. The conductive paper according to the present invention possesses the function as paper without impairing the characteristics and form of the base material cellulose, and at the same time has high conductivity imparted from a conductive substance.
　かかる導電紙は、本発明によりはじめて実現が可能となった革新的な新しい材料であり、その優れた導電性によって、電子回路の配線パターン等に好適に用いることができるものである。
　また、セルロース（セルロース繊維１１）と導電性物質（カーボンナノチューブ１２）とが混和した導電性セルロース１０により構成されるため、導電紙中に導電性物質の複雑なネットワークが形成されている。そのため、従来から知られている導電性物質を紙に含浸させた導電紙では到底得られなかった高い導電率を得ることができる。本発明に係る導電紙及び導電性セルロース組成物の好適な導電率に上限はないが、導電材料自体の導電率を凌駕する導電性を得ることはできない。導電率が１Ｓ／ｃｍ以上であれば、電子回路の配線として用いることができ好適である。 Such a conductive paper is an innovative new material that can be realized for the first time by the present invention, and can be suitably used for a wiring pattern of an electronic circuit because of its excellent conductivity.
In addition, since it is composed of the conductive cellulose 10 in which cellulose (cellulose fibers 11) and a conductive substance (carbon nanotubes 12) are mixed, a complicated network of conductive substances is formed in the conductive paper. Therefore, it is possible to obtain a high conductivity that could not be obtained at all with a conductive paper obtained by impregnating paper with a conventionally known conductive material. Although there is no upper limit to the suitable conductivity of the conductive paper and the conductive cellulose composition according to the present invention, it is not possible to obtain conductivity that exceeds the conductivity of the conductive material itself. A conductivity of 1 S / cm or more is preferable because it can be used as wiring for an electronic circuit.
　また、本発明の導電紙では、上記のように内部に導電性物質のネットワークを有しているため、折り曲げたり伸ばしたりしても導電性を失うことがない。したがって、従来の紙の上に導電性物質の層を形成した導電紙では得られない優れた可撓性、加工性を具備した導電紙である。
　さらに、通常の紙が水に溶かすだけで容易にリサイクルできるのと同様に、本発明の導電紙は、水や溶剤に容易に再分散させることができる。したがって、熱などの高エネルギーを与えることなく容易にリサイクルすることができる。
　なお、本発明に係る導電紙の導電性や曲げ耐性、リサイクル性については、後段の実施例において詳細に説明している。 In addition, since the conductive paper of the present invention has a network of conductive materials inside as described above, it does not lose its conductivity even if it is folded or stretched. Therefore, it is a conductive paper having excellent flexibility and workability that cannot be obtained by a conductive paper in which a conductive material layer is formed on a conventional paper.
Furthermore, the conductive paper of the present invention can be easily redispersed in water or a solvent, just as ordinary paper can be easily recycled simply by dissolving it in water. Therefore, it can be easily recycled without giving high energy such as heat.
The conductivity, bending resistance, and recyclability of the conductive paper according to the present invention are described in detail in the following examples.
　また本発明の導電紙は、紙状や薄膜状に限らず、型枠などを用いて導電性セルロース組成物を固形物（棒状、箱状、枠状、筒状などの三次元構造物）に加工したものも含む。さらには、固体の導電紙に機械加工を加えてもよい。例えば、板状の導電紙をプレス加工等により延伸することで薄くしてもよい。このような固形物として形成された導電紙や加工を施した導電紙も、物品の導電部材や電子回路の構成部材として好適に用いることができる。 The conductive paper of the present invention is not limited to paper or thin film, and the conductive cellulose composition is made into a solid material (three-dimensional structure such as rod, box, frame, and cylinder) using a mold or the like. Includes processed products. Furthermore, machining may be added to solid conductive paper. For example, the sheet-like conductive paper may be thinned by stretching by press working or the like. Conductive paper formed as such a solid substance or processed conductive paper can also be suitably used as a conductive member of an article or a constituent member of an electronic circuit.
　本発明の導電紙は、通常、導電性セルロース１０とともに、その製造工程で用いたイオン液体を含んでいる。イオン液体は、常温溶融塩または単に溶融塩などとも称されるものであり、常温を含む幅広い温度域で溶融状態を呈する塩である。イオン液体の詳細については後段の製造方法の説明において述べるが、このイオン液体も、本発明の導電紙において導電率を高める作用を奏する。また、イオン液体は常温で液体であるため、イオン液体を含んだ導電紙はしっとりとしたなめらかな質感を呈し、より紙に近いものとなる。 The conductive paper of the present invention usually contains the ionic liquid used in the manufacturing process together with the conductive cellulose 10. The ionic liquid is also called a room temperature molten salt or simply a molten salt, and is a salt that exhibits a molten state in a wide temperature range including normal temperature. The details of the ionic liquid will be described in the description of the production method at a later stage, and this ionic liquid also has the effect of increasing the conductivity in the conductive paper of the present invention. In addition, since the ionic liquid is a liquid at room temperature, the conductive paper containing the ionic liquid exhibits a moist and smooth texture and is closer to paper.
　なお、イオン液体は、導電紙や導電性セルロース組成物からソックスレー法などを用いて除去することもできる。イオン液体を除去した導電紙（導電性セルロース組成物）の導電性は、イオン液体を含む場合と比較して低下するが、除去したイオン液体は回収することができ、導電性セルロース組成物の製造に再利用することができる。このようにイオン液体を循環利用する製造プロセスを採用することで、導電性セルロース組成物の製造コストを大幅に低減することが可能である。 Note that the ionic liquid can also be removed from the conductive paper or the conductive cellulose composition by using a Soxhlet method or the like. The conductivity of the conductive paper (conductive cellulose composition) from which the ionic liquid has been removed is lower than that of the conductive paper containing the ionic liquid, but the removed ionic liquid can be recovered and the conductive cellulose composition can be produced. Can be reused. By adopting a manufacturing process that circulates and uses an ionic liquid in this way, it is possible to significantly reduce the manufacturing cost of the conductive cellulose composition.
　また本発明の導電性セルロース組成物の他の代表的な形態は、導電性セルロース１０の分散液である。かかる分散液は、イオン液体や分散媒の性状により液体状、ゲル状、ペースト状など種々の形態を採りうる。このような流動性を有する分散液は、熱や乾燥等で固化させることで導電紙に加工でき、成形加工された導電紙を製造するのに好適である。 Further, another representative form of the conductive cellulose composition of the present invention is a dispersion of conductive cellulose 10. Such a dispersion can take various forms such as a liquid, a gel, and a paste depending on the properties of the ionic liquid and the dispersion medium. Such a fluid dispersion can be processed into conductive paper by solidifying it by heat, drying, or the like, and is suitable for producing a molded conductive paper.
　すなわち、調製された導電性セルロースの分散液を、スクリーン印刷、インクジェット印刷、ディスペンサーなどを含むあらゆる印刷機のインク（液体材料）として用いて所定のパターンに印刷し、次いで乾燥させることにより、導電紙から成るパターンや配線を容易に形成することができる。このようにして、導電性セルロースからなるパターンや配線を備える物品や、導電性セルロース組成物を備える電子回路を製造することができる。 In other words, the prepared conductive cellulose dispersion is used as ink (liquid material) for any printing press including screen printing, ink jet printing, dispenser, etc., and printed in a predetermined pattern, and then dried to produce conductive paper. It is possible to easily form patterns and wirings made of Thus, an article provided with a pattern or wiring made of conductive cellulose, or an electronic circuit provided with a conductive cellulose composition can be produced.
　また、導電紙、又は導電性セルロースの分散液には、導電性セルロースを構成する導電性物質と同一あるいは異なる導電性物質を添加することができる。例えば、導電性セルロースの分散液に、さらにカーボンナノチューブや銀ナノチューブなどの繊維状導電体を添加することで、さらに高い導電性や紙としての強さを得ることもできる。 In addition, a conductive material that is the same as or different from the conductive material constituting the conductive cellulose can be added to the conductive paper or the conductive cellulose dispersion. For example, by adding a fibrous conductor such as carbon nanotube or silver nanotube to the dispersion of conductive cellulose, higher conductivity and strength as paper can be obtained.
　以下、本発明に係る導電性セルロース組成物の構成要素について具体的に説明する。
　まず、導電性セルロース１０を構成する導電性物質としては、単層カーボンナノチューブ（ＳＷＮＴ）及び多層カーボンナノチューブ（ＭＷＮＴ）を含むカーボンナノチューブ１２に限らず、銀をはじめとした金属ナノチューブ（金属ナノファイバー）、導電性ポリマーなど、導電性を有する材料であればいかなる導電性物質も用いることができる。
　ただし、導電性物質はセルロースと混和させることができる形態である必要がある。そのため、導電性物質の種類は問わないが、セルロースの繊維と同等以下のサイズに製造又は加工された導電性物質が用いられる。 Hereinafter, the components of the conductive cellulose composition according to the present invention will be specifically described.
First, the conductive material constituting the conductive cellulose 10 is not limited to the carbon nanotubes 12 including single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT), but also metal nanotubes (metal nanofibers) including silver. Any conductive material can be used as long as it is a conductive material such as a conductive polymer.
However, the conductive material needs to be in a form that can be mixed with cellulose. Therefore, the type of the conductive material is not limited, but a conductive material manufactured or processed to a size equal to or smaller than that of cellulose fibers is used.
　高導電性を持ち、かつ紙のようにしなやかな導電紙あるいは導電性セルロース組成物を実現するためには、導電性の高い導電性物質を用いることが重要である。特にカーボンナノチューブを用いる場合、カーボンナノチューブが長いこと、純度が高いこと、及び比表面積が高いことが好ましい。そのため、一般的に比表面積が低く、長さも短い多層カーボンナノチューブより、比表面積が高く、長さも長い単層カーボンナノチューブがより好ましい。 In order to realize a conductive paper or a conductive cellulose composition having high conductivity and being supple like paper, it is important to use a conductive material having high conductivity. In particular, when carbon nanotubes are used, it is preferable that the carbon nanotubes are long, have high purity, and have a high specific surface area. Therefore, in general, single-walled carbon nanotubes having a high specific surface area and a long length are more preferable than multi-walled carbon nanotubes having a low specific surface area and a short length.
　まず、カーボンナノチューブは、可能な限り長いものであることが望ましい。
　これは、導電性セルロース組成物中のカーボンナノチューブのネットワーク（編み目構造）が長いカーボンナノチューブにより構成された場合、より電気を通す経路が多く形成でき、かつ折り曲げた場合においてもネットワークがより破壊されにくいためである。 First, the carbon nanotube is desirably as long as possible.
This is because, when the carbon nanotube network (knitted structure) in the conductive cellulose composition is composed of long carbon nanotubes, more paths for conducting electricity can be formed, and even when bent, the network is more difficult to break. Because.
　導電性セルロース組成物において高導電性、しなやかさを得る上での導電性物質の長さには上限はないが、一般的に長い材料はより分散性が低くなり導電性セルロース組成物の製造が困難となる。例えば、カーボンナノチューブを用いる場合には、長さが１μｍ以上１０ｃｍ以下の長さのカーボンナノチューブは分散性が良く、高純度のものが得やすく、高導電性、しなやかさを得る上で好ましい。長さが１μｍ以下となると、導電率が極端に下がるので、好ましくない。逆に長さが１０ｃｍ以上のカーボンナノチューブは分散性が悪く、かつ分散処理中に容易に切断される。 There is no upper limit to the length of the conductive material for obtaining high conductivity and flexibility in the conductive cellulose composition, but in general, longer materials have lower dispersibility and the production of the conductive cellulose composition can be reduced. It becomes difficult. For example, when carbon nanotubes are used, carbon nanotubes having a length of 1 μm or more and 10 cm or less have good dispersibility, are easily obtained with high purity, and are preferable for obtaining high conductivity and flexibility. When the length is 1 μm or less, the conductivity is extremely lowered, which is not preferable. Conversely, carbon nanotubes having a length of 10 cm or more have poor dispersibility and are easily cut during the dispersion process.
　なお、カーボンナノチューブは、ナノスケールの直径をもちつつ、長さは長い非常に細長いナノマテリアルであるため、一本一本の長さを測定することは非常に困難である。本発明の場合には、カーボンナノチューブの長さを測定するに際して、以下の方法を用いることができる。 In addition, since the carbon nanotube is a very long and narrow nanomaterial having a nanoscale diameter and a long length, it is very difficult to measure the length of each one. In the case of the present invention, the following method can be used when measuring the length of the carbon nanotube.
　まず、カーボンナノチューブとイオン液体との混合物、あるいはかかる混合物にセルロースを分散させた分散液を有機溶剤等で薄く希釈した液体試料を調製する。次いで、液体試料を基板上に滴下後乾燥させたものを、走査型原子間力顕微鏡等で観察する。このとき、一本一本のカーボンナノチューブの長さではなく、バンドル（カーボンナノチューブの束）の長さを測定する。
　走査型原子間力顕微鏡で測定したカーボンナノチューブのバンドルの長さと、バンドルを構成するカーボンナノチューブの長さには相関性があり、長いカーボンナノチューブにより構成されるバンドルは長くなる。これにより、カーボンナノチューブの長さを評価可能である。 First, a liquid sample is prepared by thinly diluting a mixture of carbon nanotubes and ionic liquid, or a dispersion in which cellulose is dispersed in such a mixture with an organic solvent or the like. Next, the liquid sample dropped onto the substrate and then dried is observed with a scanning atomic force microscope or the like. At this time, the length of the bundle (bundle of carbon nanotubes) is measured instead of the length of each carbon nanotube.
There is a correlation between the length of the carbon nanotube bundle measured by the scanning atomic force microscope and the length of the carbon nanotube constituting the bundle, and the bundle constituted by the long carbon nanotube becomes long. Thereby, the length of the carbon nanotube can be evaluated.
　本発明の場合、カーボンナノチューブの特性や長さに制限はなく導電性セルロース組成物を作製できるが、より高い導電性、しなやかさを得られる長いカーボンナノチューブとしては、スーパーグロース法により作製したカーボンナノチューブを例示することができる。
　スーパーグロース法によるカーボンナノチューブの製造方法は、例えば、国際公開第０６／０１１６５５号パンフレットに記載されている。スーパーグロース法は、水分添加ＣＶＤ法によりカーボンナノチューブを合成する技術であり、長く高純度の単層カーボンナノチューブが得られる。スーパーグロース法では、成長基板上に垂直配向したカーボンナノチューブ配向集合体を成長させることができ、このカーボンナノチューブ配向集合体を成長基板から剥離して用いることができる。本発明においてこの剥離したカーボンナノチューブ配向集合体を用いる場合には、カーボンナノチューブ配向集合体の高さをカーボンナノチューブの長さとして規定することができる。 In the case of the present invention, there is no limitation on the characteristics and length of the carbon nanotube, and a conductive cellulose composition can be produced. However, as a long carbon nanotube that can obtain higher conductivity and flexibility, a carbon nanotube produced by a super-growth method is used. Can be illustrated.
A method for producing carbon nanotubes by the super-growth method is described, for example, in International Publication No. 06/011655. The super-growth method is a technique for synthesizing carbon nanotubes by a moisture-added CVD method, and long and high-purity single-walled carbon nanotubes can be obtained. In the super-growth method, a carbon nanotube alignment aggregate vertically aligned on a growth substrate can be grown, and this carbon nanotube alignment aggregate can be peeled off from the growth substrate and used. In the present invention, when this separated aligned carbon nanotube assembly is used, the height of the aligned carbon nanotube assembly can be defined as the length of the carbon nanotube.
　次に、高導電性を得るためには、カーボンナノチューブが可能な限り高純度であることが望ましい。
　ここでいう純度とは、炭素純度であり、カーボンナノチューブの重量の何パーセントが炭素で構成されているかを示す。高導電性、高い伸長率を得る上での純度に上限はないが、製造上の都合から、９９．９９９９％以上のカーボンナノチューブを得ることは困難である。金属などの不純物を含んで炭素純度が９０％に満たないと、金属不純物が製造プロセス中に凝集し、カーボンナノチューブがセルロースの繊維に絡みづらくなって混和が不十分になるため、高導電性、高い曲げ耐性を得ることが困難となる。これらの点から、カーボンナノチューブの純度は９０％以上であることが好ましい。 Next, in order to obtain high conductivity, it is desirable that the carbon nanotubes be as pure as possible.
Purity here is carbon purity and shows what percentage of the weight of a carbon nanotube is comprised with carbon. Although there is no upper limit to the purity for obtaining high conductivity and high elongation, it is difficult to obtain 99.9999% or more of carbon nanotubes for the convenience of production. When impurities such as metals are included and the carbon purity is less than 90%, the metal impurities are aggregated during the manufacturing process, and the carbon nanotubes are not easily entangled with the fibers of cellulose, resulting in insufficient mixing. It becomes difficult to obtain high bending resistance. From these points, the purity of the carbon nanotube is preferably 90% or more.
　カーボンナノチューブの純度は、蛍光Ｘ線を用いた元素分析結果より得られる。後述する具体例で用いたスーパーグロース（ＳＧ）単層カーボンナノチューブ（ＳＷＮＴ）を蛍光Ｘ線によって元素分析したところ、炭素が９９．９８％、鉄が０．０１３％であり、その他の元素は計測されなかった。 The purity of carbon nanotubes is obtained from the results of elemental analysis using fluorescent X-rays. Super-growth (SG) single-walled carbon nanotubes (SWNT) used in specific examples to be described later were subjected to elemental analysis by fluorescent X-rays. As a result, carbon was 99.98%, iron was 0.013%, and other elements were measured. Was not.
　次に、高導電性、高い曲げ耐性を得るためには、カーボンナノチューブが可能な限り高比表面積であることが望ましい。
　これは、高比表面積のカーボンナノチューブは、表面が多いため、導電性セルロース組成物の製造プロセスで用いるイオン液体との界面が多くなり相互作用しやすいためである。また、高比表面積のカーボンナノチューブは、カーボンナノチューブ以外の炭素不純物、金属等の炭素以外の不純物の含有が少なく、上記した理由で好適である。比表面積が６００ｍ２／ｇに満たない単層カーボンナノチューブは、金属などの不純物もしくは炭素不純物を重量の数十パーセント（４０％程度）含んでおり、単層カーボンナノチューブ本来の機能を発現することができず、不適である。 Next, in order to obtain high conductivity and high bending resistance, it is desirable that the carbon nanotube has as high a specific surface area as possible.
This is because carbon nanotubes having a high specific surface area have many surfaces, and therefore, the number of interfaces with the ionic liquid used in the production process of the conductive cellulose composition increases, and the carbon nanotubes easily interact with each other. Carbon nanotubes with a high specific surface area contain a small amount of carbon impurities other than carbon nanotubes and impurities such as metals other than carbon, and are suitable for the reasons described above. Single-walled carbon nanotubes having a specific surface area of less than 600 m 2 / g contain impurities such as metals or carbon impurities of several tens of percent (about 40%) by weight, and may exhibit the original functions of single-walled carbon nanotubes. It cannot be done and is inappropriate.
　単層カーボンナノチューブの比表面積は、一般的には大きければ大きいほど好ましいが、理論的に上限があり、未開口のものは１３００ｍ２／ｇ程度であり、開口したものは２６００ｍ２／ｇ程度である。
　単層カーボンナノチューブの比表面積は、液体窒素の７７Ｋでの吸脱着等温線の計測によって求めることができる。その一例として、単層ＣＮＴ配向集合体３０ｍｇについて、ＢＥＬＳＯＲＰ－ＭＩＮＩ（株式会社日本ベル製）を用いて計測した吸脱着等温曲線から求めることができる（吸着平衡時間は６００秒とした）。本発明で用いた、単層カーボンナノチューブの吸脱着等温曲線からBrunauer,Emmett,Tellerの方法で比表面積を計測したところ、１１００ｍ２／ｇであった。
　なお、開口処理温度を３５０℃から６００℃に変化させることにより、１０００ｍ２／ｇ～２３００ｍ２／ｇの範囲で単層カーボンナノチューブの比表面積を変化させることができ、かかる単層カーボンナノチューブは高い導電性を有する本発明のセルロース組成物を実現するのに好適である。 In general, the larger the specific surface area of the single-walled carbon nanotube, the better. However, there is a theoretical upper limit, the unopened one is about 1300 m 2 / g, and the opened one is about 2600 m 2 / g. is there.
The specific surface area of the single-walled carbon nanotube can be obtained by measuring an adsorption / desorption isotherm of liquid nitrogen at 77K. As an example, 30 mg of the aligned single-walled CNT aggregate can be obtained from an adsorption / desorption isotherm curve measured using BELSORP-MINI (manufactured by Nippon Bell Co., Ltd.) (adsorption equilibrium time was 600 seconds). Used in the present invention, Brunauer from adsorption and desorption isothermal curve of the single-walled carbon nanotubes, Emmett, was measured specific surface area Teller method was 1100 m 2 / g.
Incidentally, by changing the aperture processing temperature from 350 ° C. to 600 ° C., it is possible to change the specific surface area of the single-walled carbon nanotubes in the range of 1000m 2 / g ~ 2300m 2 / g, such single-walled carbon nanotubes is higher It is suitable for realizing the cellulose composition of the present invention having conductivity.
　一方、導電性ポリマーとしては、ポリアニリン系高分子、ポリピロール系高分子、ポリチオフェン系高分子等を挙げることができる。特に高導電性のポリマーとして、例えば、ポリパラフェニレン、ポリアニリン、ポリチオフェン、ポリパラフェニレンビニレン、ポリピロール、ポリアセチレン、ポリフェニレンビニレン、ポリエチレンジオキシチオフェン（以下単にＰＥＤＯＴと記す）を挙げることができる。典型的な例はＰＥＤＯＴであり、その水性分散液はＴＡケミカル社より商品名「Ｂａｙｔｒｏｎ　ＰＨ５００」として市販されている。またＰＥＤＯＴを用いる場合にはジメチルスルホキシドを併用することが好ましい。ジメチルスルホキシドの添加により、ＰＥＤＯＴの導電性を著しく向上させることができる。 On the other hand, examples of the conductive polymer include a polyaniline polymer, a polypyrrole polymer, and a polythiophene polymer. Examples of particularly highly conductive polymers include polyparaphenylene, polyaniline, polythiophene, polyparaphenylene vinylene, polypyrrole, polyacetylene, polyphenylene vinylene, and polyethylenedioxythiophene (hereinafter simply referred to as PEDOT). A typical example is PEDOT, and its aqueous dispersion is commercially available from TA Chemical Company under the trade name “Baytron PH500”. When PEDOT is used, it is preferable to use dimethyl sulfoxide in combination. By adding dimethyl sulfoxide, the conductivity of PEDOT can be significantly improved.
　セルロースと混和する導電性物質として導電性ポリマーを用いた場合には、導電性ポリマーのサイズがセルロース繊維１１やカーボンナノチューブ１２と比べて小さいため、図１（ｂ）に示したようにセルロース繊維１１に絡みつくのではなく、セルロース繊維１１の表面を覆うように導電性ポリマーが吸着して導電性セルロース１０となる。このようにセルロース繊維１１に導電性ポリマーが吸着した導電性セルロース１０は、分散媒に分散させてもセルロース繊維１１と導電性ポリマーとが相分離することはなく、このような状態を本発明ではセルロースと導電性ポリマーとが混和した状態と定義している。このように吸着した導電性ポリマーは、セルロース及び導電性ポリマーを損傷することなく分離することができない状態にある。 When a conductive polymer is used as a conductive substance mixed with cellulose, the size of the conductive polymer is smaller than that of the cellulose fiber 11 and the carbon nanotube 12, and therefore the cellulose fiber 11 as shown in FIG. The conductive polymer is adsorbed so as to cover the surface of the cellulose fiber 11 and become the conductive cellulose 10. Thus, even if the conductive cellulose 10 in which the conductive polymer is adsorbed on the cellulose fiber 11 is dispersed in the dispersion medium, the cellulose fiber 11 and the conductive polymer are not phase-separated. It is defined as a state in which cellulose and a conductive polymer are mixed. The conductive polymer thus adsorbed cannot be separated without damaging the cellulose and the conductive polymer.
　本発明において用いられるセルロースは、特に制限されるものではなく、通常の抄紙に用いられるセルロース材料（集合体はパルプ）のいかなるものであってもよい。一般的に知られているパルプは、セルロースの繊維から形成されている。例えば、木材パルプ、古紙パルプ、非木材パルプ、より具体的には針葉樹亜硫酸パルプ、針葉樹漂白クラフトパルプ、広葉樹亜硫酸パルプ、広葉樹漂白クラフトパルプ、リンターパルプなどあらゆる繊維状のパルプでもかまわない。
　またセルロースとしては、天然セルロース、再生セルロース、綿セルロース、リンター、レイヨン、非晶セルロースなど、あらゆるセルロースを用いることができる。さらには、これらのパルプ、セルロースに限らず、水素結合を生じる繊維であれば原料として使用できるため、草・藁・竹などの原料からパルプを抽出したものでもかまわない。 The cellulose used in the present invention is not particularly limited, and may be any cellulose material (aggregate is pulp) used for ordinary papermaking. Commonly known pulp is formed from cellulose fibers. For example, any fibrous pulp such as wood pulp, waste paper pulp, non-wood pulp, more specifically softwood sulfite pulp, softwood bleached kraft pulp, hardwood sulfite pulp, hardwood bleached kraft pulp, and linter pulp may be used.
As the cellulose, any cellulose such as natural cellulose, regenerated cellulose, cotton cellulose, linter, rayon, and amorphous cellulose can be used. Furthermore, the pulp is not limited to cellulose and cellulose, and any fiber that generates hydrogen bonds can be used as a raw material. Therefore, pulp extracted from raw materials such as grass, straw, and bamboo may be used.
　上記のパルプ及びセルロースのうちでも、特に導電性に優れた紙を得るためには、あらかじめ細かいセルロース繊維に解繊されたミクロフィブリルセルロースを用いることが好ましい。かかるミクロフィブリルセルロースもまた特に制限されるものではなく、市販のいかなるものであってもよい。市販のミクロフィブリルセルロースの典型的な例としては、ダイセル化学工業社製のＣｅｌｉｓｈがある。 Among the above pulp and cellulose, it is preferable to use microfibril cellulose that has been defibrated in advance into fine cellulose fibers in order to obtain paper having excellent conductivity. Such microfibril cellulose is not particularly limited, and may be any commercially available one. A typical example of commercially available microfibril cellulose is Celish manufactured by Daicel Chemical Industries.
　（導電性セルロース組成物及び導電紙の製造方法）
　例えば導電性物質としてカーボンナノチューブを用いる場合、本発明の導電性セルロース組成物においては、カーボンナノチューブが組成物内に均一分散されているほど高い導電性が得られる。つまり、高導電性及びしなやかさを兼ね備える本発明の導電性セルロース組成物を実現するためには、長く、純度が高く、比表面積が高いカーボンナノチューブを、その機能を損なわずに、如何にセルロース中に均一分散するかが肝要となる。
　一般的には、カーボンナノチューブは非常に溶解性が低い材料で、セルロースとの親和性は低く、セルロース内に分散しない。そのために、カーボンナノチューブを均一分散し、高導電性及びしなやかさを兼ね備えた導電性セルロース組成物及び導電紙の実現は著しく困難であった。 (Conductive cellulose composition and method for producing conductive paper)
For example, when carbon nanotubes are used as the conductive substance, in the conductive cellulose composition of the present invention, higher conductivity is obtained as the carbon nanotubes are uniformly dispersed in the composition. That is, in order to realize the conductive cellulose composition of the present invention having both high conductivity and flexibility, a carbon nanotube having a long length, high purity, and high specific surface area can be obtained without degrading its function. It is important to uniformly disperse the water.
In general, carbon nanotubes are materials with very low solubility, have low affinity with cellulose, and do not disperse in cellulose. Therefore, it has been extremely difficult to realize a conductive cellulose composition and conductive paper in which carbon nanotubes are uniformly dispersed and have both high conductivity and flexibility.
　本発明者は誠意工夫を重ね、カーボンナノチューブを含み導電性材料とセルロースの分散性を高めるために、イオン液体を用いると好適であることを見出した。
　例えば、特開２００５－１７６４２８号公報に記述されているように、カーボンナノチューブとイオン液体は親和性が高く、カーボンナノチューブをイオン液体中に分散処理することで、ゲル状になる。このようにカーボンナノチューブとイオン液体のゲル状組成物が形成される詳しい機構は現時点では不明であるが、イオン液体が一本一本のカーボンナノチューブに吸着し、カーボンナノチューブ同士をくっつけているファンデルワールス力を弱めていると考えられる。その結果、通常容易にバンドル化するカーボンナノチューブが、イオン液体中で分散し、ゲル状組成物を形成する。いわば、カーボンナノチューブの分散剤としてイオン液体が機能すると考えられる。 The present inventor has made sincerity and found that it is preferable to use an ionic liquid in order to increase the dispersibility of the conductive material and cellulose including carbon nanotubes.
For example, as described in Japanese Patent Application Laid-Open No. 2005-176428, carbon nanotubes and ionic liquid have a high affinity, and the carbon nanotubes are gelled by being dispersed in the ionic liquid. Although the detailed mechanism of the formation of a gel composition of carbon nanotubes and ionic liquid is unknown at this time, van der is that the ionic liquid is adsorbed on each carbon nanotube and bonds the carbon nanotubes together. It is thought that the virus power is weakened. As a result, the carbon nanotubes that are usually easily bundled are dispersed in the ionic liquid to form a gel composition. In other words, the ionic liquid is considered to function as a dispersant for carbon nanotubes.
　さらに本発明においては、発明者は、イオン液体と混和するセルロースおよび導電性物質を用いると、上記ゲル状組成物中にセルロースを均一に分散させた分散液を得ることができることを見いだし、本発明の導電性が高く、紙のしなやかさを兼ね備える導電性セルロース組成物及び導電紙を製造する方法を実現した。
　混和により、導電性セルロース組成物が形成される詳しい機構は現時点では不明であるが、導電性物質に吸着したイオン液体が、セルロースとも親和性を持ち混和することで、導電性物質をセルロース中に溶け込ませることを可能にし、通常ではセルロース中に分散が困難なカーボンナノチューブなどの導電性物質がセルロース中に均一に分散するものと考える。 Furthermore, in the present invention, the inventor has found that when cellulose and a conductive substance that are miscible with the ionic liquid are used, a dispersion in which cellulose is uniformly dispersed in the gel composition can be obtained. The conductive cellulose composition having high electrical conductivity and the flexibility of paper and a method for producing conductive paper have been realized.
The detailed mechanism by which the conductive cellulose composition is formed by mixing is unknown at this time. However, the ionic liquid adsorbed on the conductive material has affinity with cellulose and mixes the conductive material into the cellulose. It is considered that a conductive substance such as a carbon nanotube that can be dissolved and normally difficult to disperse in cellulose is uniformly dispersed in cellulose.
　ここで、上記分散液における混和とは、イオン液体と、セルロースや母材となるパルプ、必要に応じて水や有機溶剤を含む分散溶液が相分離しない程度に混ざり合うことを言う。混和の程度に上限はなく、実質的に、導電性セルロース組成物とイオン液体、そして必要に応じて水や有機溶剤が混ざり合い、最終的に高導電性、しなやかさを兼ね備える導電性セルロース組成物を製造できる程度であれば良く、通常イオン液体とセルロースやセルロースのパルプ、必要に応じて水や有機溶剤を含む分散液が数時間、より好ましくは数日間相分離しない程度であれば好適である。イオン液体とセルロースやセルロースのパルプ、必要に応じて水や有機溶剤が相溶性を示すことは、より良い分散性を実現するために好ましい。ここで、相溶性とは、２種類または多種類の物質が相互に親和性を有し、溶液または混和物を形成する性質をいう。 Here, the mixing in the dispersion means that the ionic liquid, cellulose, pulp as a base material, and, if necessary, a dispersion containing water or an organic solvent are mixed to such an extent that they do not undergo phase separation. There is no upper limit to the degree of blending, and the conductive cellulose composition, the ionic liquid, and water and organic solvents, if necessary, are finally mixed together. Finally, the conductive cellulose composition has high conductivity and flexibility. In general, it is suitable if the dispersion containing an ionic liquid and cellulose or cellulose pulp, and water or an organic solvent as required, does not undergo phase separation for several hours, more preferably for several days. . It is preferable that the ionic liquid and cellulose or cellulose pulp and, if necessary, water or an organic solvent are compatible with each other in order to achieve better dispersibility. Here, the term “compatible” refers to the property that two or more substances have an affinity for each other and form a solution or a mixture.
　本発明の導電性セルロース組成物の製造方法は、上記知見に基づき成されたものであり、イオン液体と導電性物質との混合物を調製する工程１と、前記混合物にセルロースを分散させて分散液を調製する工程２と、を有することを特徴とする。
　また本発明の導電紙の製造法は、上記知見に基づき成されたものであり、イオン液体と導電性物質との混合物を調製する工程１と、前記混合物にセルロースを分散させて分散液を調製する工程２と、前記分散液を乾燥させる工程３と、を有することを特徴とする。 The method for producing a conductive cellulose composition of the present invention is based on the above findings, Step 1 of preparing a mixture of an ionic liquid and a conductive material, and dispersing the cellulose in the mixture Step 2 of preparing
The method for producing a conductive paper according to the present invention is based on the above knowledge. Step 1 of preparing a mixture of an ionic liquid and a conductive substance, and preparing a dispersion by dispersing cellulose in the mixture And a step 3 of drying the dispersion.
　以下、これら導電性セルロース組成物及び導電紙の製造方法について、図面を参照しつつ説明する。
　図２は、本発明の一実施形態である導電紙の製造方法を示すフロー図である。図２に示すように、本発明の導電紙の製造方法は、導電性物質とイオン液体との混合物を調製する混合物調製工程Ｓ１と、得られた混合物にセルロースを分散させて分散液を調製する分散液調製工程Ｓ２とにより導電性セルロース組成物を作製する工程を含み、さらに得られた導電性セルロース組成物を乾燥させて導電紙を作製する乾燥工程Ｓ３を含む。導電紙からイオン液体を回収するイオン液体回収工程Ｓ４は、必要に応じて実施される工程である。 Hereinafter, these conductive cellulose compositions and methods for producing conductive paper will be described with reference to the drawings.
FIG. 2 is a flowchart showing a method for producing conductive paper according to an embodiment of the present invention. As shown in FIG. 2, the method for producing conductive paper of the present invention comprises a mixture preparation step S1 for preparing a mixture of a conductive substance and an ionic liquid, and a dispersion is prepared by dispersing cellulose in the obtained mixture. It includes a step of producing a conductive cellulose composition by the dispersion liquid preparation step S2, and further includes a drying step S3 of drying the obtained conductive cellulose composition to produce conductive paper. The ionic liquid recovery step S4 for recovering the ionic liquid from the conductive paper is a step performed as necessary.
　混合物調製工程Ｓ１で用いられる導電性物質としては、先に記載のように、セルロースと混和可能な導電性物質であればいかなるものも用いることができる。すなわち、カーボンナノチューブや金属ナノチューブ、高導電性ポリマー等を用いることができる。 As the conductive material used in the mixture preparation step S1, any conductive material that is miscible with cellulose can be used as described above. That is, carbon nanotubes, metal nanotubes, highly conductive polymers, and the like can be used.
　本発明において、イオン液体とは、常温溶融塩または単に溶融塩などとも称されるものであり、常温を含む幅広い温度域で溶融状態を呈する塩である。本発明においては、従来から知られた各種のイオン液体を使用することができ、例えば、特許第３６７６３３７号公報や特許第３８８０５８０号公報に記載されているものを挙げることができる。 In the present invention, the ionic liquid is also called a room temperature molten salt or simply a molten salt, and is a salt that exhibits a molten state in a wide temperature range including normal temperature. In the present invention, conventionally known various ionic liquids can be used, and examples thereof include those described in Japanese Patent No. 3676337 and Japanese Patent No. 3880580.
　本発明においては、かかるイオン液体として、親水性および疎水性イオン液体のいずれをも用いることができる。親水性イオン液体としては、例えば、Ｎ，Ｎ－ジエチル－Ｎ－メチル－Ｎ－（２－メトキシエチル）アンモニウム　テトラフルオロボレート（ＤＥＭＥＢＦ４）を挙げることができる。ただし、この親水性イオン液体に限らず、水と混和するイオン液体は、このプロセスに用いることができる。 In the present invention, both hydrophilic and hydrophobic ionic liquids can be used as the ionic liquid. Examples of the hydrophilic ionic liquid include N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate (DEMEBF 4 ). However, not only this hydrophilic ionic liquid but also an ionic liquid miscible with water can be used in this process.
　疎水性イオン液体としては、例えば、Ｎ，Ｎ－ジエチル－Ｎ－メチル－Ｎ－（２－メトキシエチル）アンモニウム　ビス（トリフルオロメチルスルホニル）イミド（ＤＥＭＥＴＦＳＩ）、１－エチル－３－メチルイミダゾリウム　テトラフルオロボレート（ＥＭＩＢＦ４）、１－エチル－３－メチルイミダゾリウム　ヘキサフルオロホスフェート（ＥＭＩＰＦ６）、１－エチル－３－メチルイミダゾリウム　ビス（トリフルオロメチルスルホニル）イミド（ＥＭＩＴＦＳＩ）、１－ブチル－３－メチルイミダゾリウム　テトラフルオロボレート（ＢＭＩＢＦ４）、１－ブチル－３－メチルイミダゾリウム　ヘキサフルオロホスフェート（ＢＭＩＰＦ６）、１－ブチル－３－メチルイミダゾリウム　ビス（トリフルオロメチルスルホニル）イミド（ＢＭＩＴＦＳＩ）を挙げることができる。
　また、特に制限されるものではないが、導電性物質及びセルロースと親和性が高く、分散処理をした際にゲル状となるイオン液体は、本発明に係る導電性セルロース組成物の製造に有用である。 Examples of the hydrophobic ionic liquid include N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) imide (DEMETFSI), 1-ethyl-3-methylimidazolium tetra Fluoroborate (EMIBF 4 ), 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIPF 6 ), 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMITFSI), 1-butyl-3 - methylimidazolium tetrafluoroborate (BMIBF 4), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF 6), 1- butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ( MITFSI) can be mentioned.
Although not particularly limited, the ionic liquid that has a high affinity with the conductive material and cellulose and becomes a gel when dispersed is useful for the production of the conductive cellulose composition according to the present invention. is there.
　また、分散液調製工程Ｓ２では、混合物調製工程Ｓ１で得られた混合物に直接セルロースを分散させてもよく、必要に応じて水や有機溶剤などの分散媒を用いることができる。
　親水性のイオン液体を用いている場合には、水を好適な分散媒として用いることができる。一方、疎水性のイオン液体を用いている場合には、親水性有機溶剤を用いることが好ましい。有用な親水性有機溶剤としては、例えば、メタノール、エタノール、１－プロパノール、２－プロパノール、１－ブタノール、ギ酸、酢酸、アセトン、アセトニトリル、テトラヒドロフラン、ジメチルスルホキシド、Ｎ，Ｎ－ジメチルホルムアミドを挙げることができ、典型的な例はエタノールである。
　なお、有機溶剤は、上記に限定されるものではなく、用いるセルロースを分散、溶解する溶剤を適宜選択して用いることができる。具体的にはトルエン、キシレン、四塩化炭素等も用いることが可能である。 In the dispersion preparation step S2, cellulose may be directly dispersed in the mixture obtained in the mixture preparation step S1, and a dispersion medium such as water or an organic solvent can be used as necessary.
When a hydrophilic ionic liquid is used, water can be used as a suitable dispersion medium. On the other hand, when a hydrophobic ionic liquid is used, it is preferable to use a hydrophilic organic solvent. Examples of useful hydrophilic organic solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, formic acid, acetic acid, acetone, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, and N, N-dimethylformamide. A typical example is ethanol.
The organic solvent is not limited to the above, and a solvent that disperses and dissolves cellulose to be used can be appropriately selected and used. Specifically, toluene, xylene, carbon tetrachloride, or the like can be used.
　また、上記に挙げた水や有機溶剤などの分散媒は、分散液調製工程Ｓ２に限らず、混合物調製工程Ｓ１においても必要に応じて用いることができる。特に、導電性ポリマーであるＰＥＤＯＴを導電性物質として用いる場合には、混合物調製工程Ｓ１において、ＰＥＤＯＴ及びイオン液体に、有機溶剤であるジメチルスルホキシドを添加することが好ましい。ジメチルスルホキシドの添加により、ＰＥＤＯＴの導電性を著しく向上させる効果が得られる。 Further, the dispersion medium such as water and organic solvent mentioned above can be used not only in the dispersion preparation step S2 but also in the mixture preparation step S1 as necessary. In particular, when PEDOT, which is a conductive polymer, is used as a conductive substance, it is preferable to add dimethyl sulfoxide, which is an organic solvent, to PEDOT and the ionic liquid in the mixture preparation step S1. By adding dimethyl sulfoxide, the effect of remarkably improving the conductivity of PEDOT can be obtained.
　本発明の導電性セルロース組成物としては、有機溶剤内で分散するものも、水中で分散するものも製造することができる。本発明では、混合物調製工程Ｓ１で用いるイオン液体と、セルロースを加えた後の分散液調製工程Ｓ２で用いる分散媒との組み合わせによって、導電性セルロース組成物及び導電紙の親水性、疎水性をコントロールすることができる。 The conductive cellulose composition of the present invention can be produced either in an organic solvent or in water. In the present invention, the hydrophilicity and hydrophobicity of the conductive cellulose composition and the conductive paper are controlled by the combination of the ionic liquid used in the mixture preparation step S1 and the dispersion medium used in the dispersion preparation step S2 after adding cellulose. can do.
　具体的には、親水性の導電セルロース組成物及び導電紙を作製する場合、水と混和するセルロースと、水と混和するイオン液体を用いる。すなわち、混合物調製工程Ｓ１において、イオン液体として例えばＤＥＭＥＢＦ４を用い、分散液調製工程Ｓ２において、分散媒に水を用いて導電性物質とイオン液体と、水と混和するセルロースとを含む分散液を調製する。 Specifically, when producing a hydrophilic conductive cellulose composition and conductive paper, cellulose miscible with water and an ionic liquid miscible with water are used. That is, in the mixture preparation step S1, for example, DEMEBF 4 is used as an ionic liquid, and in the dispersion preparation step S2, a dispersion liquid containing a conductive substance, an ionic liquid, and cellulose mixed with water is used using water as a dispersion medium. Prepare.
　一方、疎水性の導電性セルロース組成物及び導電紙を作製する場合、疎水性イオン液体およびそれと混和する有機溶剤、有機溶剤と混和する導電性物質を用いる。すなわち、混合物調製工程Ｓ１において、例えばＤＥＭＥＴＦＳＩやＢＭＩＢＦ４を用い、分散液調製工程Ｓ２において、分散媒に例えばエタノールを用いて導電性物質とイオン液体とセルロースとを含む分散液を調製する。
　なお、分散媒及びセルロースには混和可能な組み合わせを選択する。例えば、ミクロフィブリルセルロースはエタノールやメタノールなどの極性を持つ溶媒（上述した親水性有機溶剤）に溶解することができるため、これらの組み合わせは疎水性導電紙の製造に好適に用いることができる。 On the other hand, when producing a hydrophobic conductive cellulose composition and conductive paper, a hydrophobic ionic liquid, an organic solvent mixed therewith, and a conductive material mixed with the organic solvent are used. That is, in the mixture preparation step S1, for example, DEMETFSI or BMIBF 4 is used, and in the dispersion preparation step S2, for example, ethanol is used as a dispersion medium to prepare a dispersion containing a conductive substance, an ionic liquid, and cellulose.
In addition, a miscible combination is selected for the dispersion medium and cellulose. For example, microfibril cellulose can be dissolved in a polar solvent such as ethanol or methanol (the hydrophilic organic solvent described above), so that these combinations can be suitably used for the production of hydrophobic conductive paper.
　以下、本発明の導電性セルロース組成物及び導電紙の製造方法のうち、特に好ましいプロセスの一例を、図２を参照しながら、以下に具体的に説明する。 Hereinafter, an example of a particularly preferable process among the conductive cellulose composition and the method for producing conductive paper of the present invention will be specifically described below with reference to FIG.
　まず、混合物調製工程Ｓ１では、上記の導電性物質及びイオン液体を用意し、これらを均一に混ぜ合わせる。これにより、導電性物質とイオン液体との混合物（ゲル状組成物）を調製する。 First, in the mixture preparation step S1, the above-described conductive substance and ionic liquid are prepared and mixed uniformly. Thereby, the mixture (gel composition) of an electroconductive substance and an ionic liquid is prepared.
　本発明の導電性セルロース組成物の製造に際して、各成分の混合分散にはジェットミル、ボールミル、超音波分散機、乳鉢、自動乳鉢等を用いることができる。これらの装置は、カーボンナノチューブや導電性ポリマーなどの導電性物質をゲル状組成物中により均一に分散させる観点、及び混合処理によるカーボンナノチューブの切断や導電性ポリマーの低分子化を回避する観点から選択される。カーボンナノチューブの切断を防止する観点からはジェットミルを用いることが好ましい。 In the production of the conductive cellulose composition of the present invention, a jet mill, a ball mill, an ultrasonic disperser, a mortar, an automatic mortar or the like can be used for mixing and dispersing each component. From these viewpoints, conductive devices such as carbon nanotubes and conductive polymers are more uniformly dispersed in the gel composition, and from the viewpoint of avoiding cutting of the carbon nanotubes and lowering of the conductive polymer due to the mixing process. Selected. From the viewpoint of preventing the carbon nanotube from being cut, it is preferable to use a jet mill.
　なお、カーボンナノチューブとイオン液体とを混合したゲル状組成物を作製する方法は、本手法に限らず、特許第３６７６３３７号公報、特許第３８８０５６０号公報、特許第３９２４２７３号公報、特開２００４－２５５４８１号公報、特開２００５－１７６４２８号公報などに記載の公知の手法を用いることもできる。また、先に記載の装置を用いた混合分散方法や上記文献に記載の方法に限定されるものではなく、導電性物質とイオン液体とを均一に混合分散させることができる方法であれば、任意の方法を採用することができる。 Note that the method for producing a gel composition in which carbon nanotubes and an ionic liquid are mixed is not limited to this method, and is disclosed in Japanese Patent Nos. 3676337, 3880560, 3924273, and 2004-254881. Known methods described in Japanese Patent Laid-Open No. 2005-176428 and the like can also be used. Further, the present invention is not limited to the mixing / dispersing method using the apparatus described above or the method described in the above document, and any method can be used as long as it can uniformly mix and disperse the conductive substance and the ionic liquid. This method can be adopted.
　次に、分散液調製工程Ｓ２では、混合物調製工程Ｓ１で得られた導電性物質とイオン液体とを含むゲル状組成物と、セルロースとを、必要により水や有機溶剤を添加して混合、分散させる。これにより、液状、ペースト状、ゲル状等の分散液の形態を成す本発明の導電性セルロース組成物を得る。 Next, in the dispersion liquid preparation step S2, the gel composition containing the conductive material and the ionic liquid obtained in the mixture preparation step S1 and cellulose are mixed and dispersed by adding water or an organic solvent as necessary. Let As a result, the conductive cellulose composition of the present invention in the form of a liquid, paste or gel dispersion is obtained.
　なお、水や有機溶剤の添加又は除去により、得られる分散液（導電性セルロース組成物）の粘度を調整することもできる。すなわち、分散液調製工程Ｓ２の前、途中、後などに、ゲル状組成物又は分散液に適宜、水や有機溶剤を追加することで、分散液の粘度を低下させることができる。あるいは、分散液調製工程Ｓ２の前、途中、後などに、ゲル状組成物又は分散液に含まれる水や有機溶剤を蒸発等させて一部除去し、分散液の粘度を上昇させることもできる。 The viscosity of the resulting dispersion (conductive cellulose composition) can be adjusted by adding or removing water or an organic solvent. That is, the viscosity of the dispersion can be reduced by adding water or an organic solvent as appropriate to the gel composition or the dispersion before, during, or after the dispersion preparation step S2. Alternatively, before or during the dispersion preparation step S2, water or an organic solvent contained in the gel composition or the dispersion can be partially removed by evaporation or the like to increase the viscosity of the dispersion. .
　また、分散液調製工程Ｓ２における混合分散にも、ジェットミル、ボールミル、超音波分散機、乳鉢、自動乳鉢等を用いることができ、これらのうちでもカーボンナノチューブの切断を防止できるジェットミルを用いることが好ましい。ただし、これらの装置を用いた混合分散方法に限定されるものではなく、導電性物質とイオン液体とセルロースとを均一に混合分散させることができる方法であれば、任意の方法を採用することができる。 In addition, a jet mill, a ball mill, an ultrasonic disperser, a mortar, an automatic mortar, or the like can also be used for mixing and dispersion in the dispersion preparation step S2, and among these, a jet mill that can prevent cutting of carbon nanotubes should be used. Is preferred. However, the present invention is not limited to the mixing / dispersing method using these apparatuses, and any method can be adopted as long as the conductive substance, the ionic liquid, and cellulose can be uniformly mixed and dispersed. it can.
　次に、乾燥工程Ｓ３では、分散液調製工程Ｓ２で得られた分散液（導電性セルロース組成物）に含まれる水や有機溶剤の一部又は全部を、乾燥、加熱、真空引き等の手段を用いて除去し、導電性セルロース組成物固化する。これにより、本発明の導電紙を得る。 Next, in the drying step S3, a part of or all of the water and the organic solvent contained in the dispersion (conductive cellulose composition) obtained in the dispersion preparation step S2 is dried, heated, evacuated, and the like. Use to remove and solidify the conductive cellulose composition. Thereby, the conductive paper of the present invention is obtained.
　なお、乾燥工程Ｓ３において所望の形状の導電紙を得るために、乾燥工程Ｓ３に先立って、分散液調製工程Ｓ２で得られた分散液（導電性セルロース組成物）を成形加工してもよい。成形加工は、流動性のあるペースト状や液状の組成物を成形加工する公知の手法を用いることができ、塗布、印刷、押し出し、キャスト、射出等を例示できる。
　ただし、導電性セルロース組成物の成形加工は、分散液の状態で行う場合に限られない。すなわち、乾燥工程Ｓ３で導電性セルロース組成物を固化した後、得られた導電紙を所望の形状に機械加工してもよい。例えば、プレス加工などによって導電紙の厚みを薄くすることもできる。 In addition, in order to obtain the conductive paper of a desired shape in drying process S3, you may shape | mold the dispersion liquid (conductive cellulose composition) obtained by dispersion liquid preparation process S2 prior to drying process S3. For the molding process, a known method for molding a fluid paste or liquid composition can be used, and examples thereof include coating, printing, extrusion, casting, and injection.
However, the forming process of the conductive cellulose composition is not limited to being performed in a dispersion state. That is, after the conductive cellulose composition is solidified in the drying step S3, the obtained conductive paper may be machined into a desired shape. For example, the thickness of the conductive paper can be reduced by pressing or the like.
　さらに、乾燥工程Ｓ３で得られた導電紙は、イオン液体回収工程Ｓ４に供することができる。このイオン液体回収工程Ｓ４は、必要に応じて実施される工程であり、ソックスレー法などを用いて導電紙からイオン液体を除去する。これにより、導電性物質とセルロースとからなる導電紙が得られる。
　イオン液体が除去された導電紙の導電性は、イオン液体を含む導電紙よりも低下する。しかしその一方で、導電紙から除去したイオン液体を回収し、図２に示すように、混合物調製工程Ｓ１で再利用することができる。これにより、製造コストを大幅に低減することができる。 Furthermore, the conductive paper obtained in the drying step S3 can be used for the ionic liquid recovery step S4. This ionic liquid recovery step S4 is a step that is performed as necessary, and removes the ionic liquid from the conductive paper using a Soxhlet method or the like. Thereby, the conductive paper which consists of an electroconductive substance and a cellulose is obtained.
The conductivity of the conductive paper from which the ionic liquid has been removed is lower than that of the conductive paper containing the ionic liquid. However, on the other hand, the ionic liquid removed from the conductive paper can be recovered and reused in the mixture preparation step S1, as shown in FIG. Thereby, manufacturing cost can be reduced significantly.
　また、図２では、乾燥後の導電紙をイオン液体回収工程Ｓ４に供することとしているが、分散液調製工程Ｓ２で得られた分散液（導電性セルロース組成物）をイオン液体回収工程Ｓ４に供してもよい。この場合にも、導電性セルロース組成物からイオン液体を回収し、再利用することが可能である。 In FIG. 2, the dried conductive paper is used for the ionic liquid recovery step S4, but the dispersion (conductive cellulose composition) obtained in the dispersion preparation step S2 is used for the ionic liquid recovery step S4. May be. Also in this case, the ionic liquid can be recovered from the conductive cellulose composition and reused.
　なお、以上に説明した製造工程は、本発明に係る導電性セルロース組成物及び導電紙を得るための製造工程の一例であり、上記例に限定されるものではない。すなわち、適宜必要に応じて、一部工程を省略したり、順序を変更しても良い。また必要に応じて、適切な工程において、他の導電性物質や他のセルロース、他の溶剤、他のイオン液体を添加してもよい。 In addition, the manufacturing process demonstrated above is an example of the manufacturing process for obtaining the electroconductive cellulose composition and conductive paper which concern on this invention, and is not limited to the said example. That is, some steps may be omitted or the order may be changed as necessary. Moreover, you may add another electroconductive substance, another cellulose, another solvent, and another ionic liquid in a suitable process as needed.
　以上、詳細に説明したように、本発明の導電性セルロース組成物及び導電紙の製造方法によれば、混合物調製工程Ｓ１において、イオン液体を用いたことで導電性物質とイオン液体とが均一に混合された混合物（ゲル状組成物）を得ることができる。特に、導電性物質としてバンドルを形成しやすいカーボンナノチューブを用いた場合にも、イオン液体の作用によりバンドルを１本１本のカーボンナノチューブに分離しつつ分散させることができる。また、導電性物質として導電性ポリマーを用いた場合にも、導電性ポリマーに親和性を示すイオン液体中に導電性ポリマーを均一に分散させることができる。 As described above in detail, according to the conductive cellulose composition and the conductive paper manufacturing method of the present invention, the conductive substance and the ionic liquid are uniformly obtained by using the ionic liquid in the mixture preparation step S1. A mixed mixture (gel composition) can be obtained. In particular, even when carbon nanotubes that easily form bundles are used as the conductive material, the bundles can be dispersed while being separated into individual carbon nanotubes by the action of the ionic liquid. In addition, even when a conductive polymer is used as the conductive substance, the conductive polymer can be uniformly dispersed in the ionic liquid having an affinity for the conductive polymer.
　また、本発明の製造方法では、混合物調製工程Ｓ１で得られたゲル状組成物（混合物）に、必要に応じて分散媒を用いつつセルロースを分散させることで、セルロースと導電性物質とをイオン液体を介して混和させ、セルロースと導電性物質とが混和してなる導電性セルロースを均一に分散させた分散液（導電性セルロース組成物）を得ることができる。
　そして、セルロースと導電性物質とが混和してなる導電性セルロースを均一に分散させた分散液から水や有機溶剤等を除去することで、導電性セルロースが絡み合い、内部に形成された導電性物質のネットワークによって高い導電性を発現する本発明の導電紙を得ることができる。 Moreover, in the manufacturing method of this invention, cellulose and an electroconductive substance are ionized by disperse | distributing cellulose to the gel-like composition (mixture) obtained by mixture preparation process S1, using a dispersion medium as needed. It is possible to obtain a dispersion (conductive cellulose composition) in which conductive cellulose formed by mixing cellulose and a conductive substance is uniformly dispersed by mixing through a liquid.
Then, the conductive cellulose is entangled by removing water, organic solvent, etc. from the dispersion liquid in which the conductive cellulose formed by mixing cellulose and the conductive substance is uniformly dispersed, and the conductive substance formed inside Thus, the conductive paper of the present invention that exhibits high conductivity can be obtained.
　また、イオン液体回収工程Ｓ４を実施すれば、作製した導電紙や分散液（導電性セルロース組成物）からイオン液体を回収することができる。そして、回収したイオン液体は混合物調製工程Ｓ１で再利用することができるため、製造コストを大幅に低減することができる。 Further, if the ionic liquid recovery step S4 is performed, the ionic liquid can be recovered from the produced conductive paper or dispersion (conductive cellulose composition). And since the collect | recovered ionic liquid can be reused by mixture preparation process S1, manufacturing cost can be reduced significantly.
　（導電紙のリサイクル方法）
　さらに、本発明の導電紙は、容易にリサイクルすることができる。図２に示すように、乾燥工程Ｓ３又はイオン液体回収工程Ｓ４を経て作製された導電紙は、溶解工程Ｓ５において液体に溶かすことで、導電性セルロースが均一に分散した分散液（導電性セルロース組成物）にすることができる。そして、導電紙を溶解して得られた分散液は、必要に応じて成形加工した後、再度乾燥工程Ｓ３に供することで、導電紙として再生することができる。 (Recycling method of conductive paper)
Furthermore, the conductive paper of the present invention can be easily recycled. As shown in FIG. 2, the conductive paper produced through the drying step S3 or the ionic liquid recovery step S4 is dissolved in a liquid in the dissolving step S5, thereby dispersing the conductive cellulose uniformly dispersed (conductive cellulose composition). Thing). And the dispersion liquid obtained by melt | dissolving conductive paper can be reproduce | regenerated as conductive paper by using the drying process S3 again, after shaping | molding as needed.
　溶解工程Ｓ５は、水や有機溶剤などの分散媒に、使用済みの導電紙を浸漬し、攪拌する工程である。溶解工程Ｓ５で用いる分散媒は、溶解する導電紙の親水性、疎水性の別に応じて適宜選択する。すなわち、親水性の導電紙を溶解する場合には分散媒として水を用い、疎水性の導電紙を溶解する場合には分散媒として有機溶剤（水以外の分散媒）を用いる。さらに、分散媒としては、溶解工程Ｓ５に供する導電紙を製造する際に、分散液調製工程Ｓ２で用いた分散媒と同一のものを用いることが好ましい。なお、必要に応じて分散媒にイオン液体を添加してもよい。 The dissolution step S5 is a step in which used conductive paper is immersed in a dispersion medium such as water or an organic solvent and stirred. The dispersion medium used in the dissolving step S5 is appropriately selected according to the hydrophilicity and hydrophobicity of the conductive paper to be dissolved. That is, water is used as a dispersion medium when dissolving hydrophilic conductive paper, and an organic solvent (dispersion medium other than water) is used as a dispersion medium when dissolving hydrophobic conductive paper. Furthermore, as the dispersion medium, it is preferable to use the same dispersion medium as used in the dispersion liquid preparation step S2 when the conductive paper to be subjected to the dissolution step S5 is manufactured. In addition, you may add an ionic liquid to a dispersion medium as needed.
　このように、本発明の導電紙は、分散媒に溶解させるという極めて簡便な工程でリサイクルすることができる。従来の電子デバイスでは導電部材に金属が用いられており、そのリサイクルには加熱などの高エネルギーが必要であったが、本発明の導電紙を用いることで、熱などの高エネルギーを与えることなく容易にリサイクル可能な電子デバイス等を形成することが可能になる。 Thus, the conductive paper of the present invention can be recycled by a very simple process of dissolving in a dispersion medium. In conventional electronic devices, metal is used for the conductive member, and recycling requires high energy such as heating, but by using the conductive paper of the present invention, high energy such as heat is not given. An electronic device that can be easily recycled can be formed.
　以下、実施例により本発明をさらに詳細に説明するが、本発明の技術範囲は本実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the technical scope of the present invention is not limited to these examples.
　［カーボンナノチューブを用いた導電紙］
　図３は、導電性物質としてカーボンナノチューブを用いた導電紙の製造プロセスの一例を示す図である。図３中、Ｓｔｅｐ１、Ｓｔｅｐ２、及びＳｔｅｐ３は、本発明の導電紙の製造方法における混合物調製工程Ｓ１、分散液調製工程Ｓ２、及び乾燥工程Ｓ３にそれぞれ対応する。 [Conductive paper using carbon nanotubes]
FIG. 3 is a diagram illustrating an example of a process for producing conductive paper using carbon nanotubes as a conductive substance. In FIG. 3, Step1, Step2, and Step3 correspond to the mixture preparation step S1, the dispersion preparation step S2, and the drying step S3, respectively, in the conductive paper manufacturing method of the present invention.
　本実施例では、導電性物質であるカーボンナノチューブとして、スーパーグロース（ＳＧ）法により作製した単層カーボンナノチューブ（純度９９．９８％超、長さ１ｍｍ未満、直径３ｎｍ）を使用した。かかるカーボンナノチューブは、例えば、ＷＯ２００６／０１１６５５に記載の方法を用いて基板から垂直し成長させた、カーボンナノチューブ配向集合体を成長基板から剥離して得られるものである。
　また、イオン液体として、テトラフルオロホウ酸Ｎ，Ｎ－ジエチル－Ｎ－メチル－Ｎ－（２－メトキシエチル）アンモニウム（ＤＥＭＥＢＦ４）を用いた。 In this example, single-walled carbon nanotubes (purity> 99.98%, length less than 1 mm, diameter 3 nm) produced by the super-growth (SG) method were used as the carbon nanotubes that are conductive materials. Such carbon nanotubes are obtained, for example, by peeling an aligned aggregate of carbon nanotubes grown from a substrate by using the method described in WO2006 / 011655 from the growth substrate.
As the ionic liquid, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate (DEMEBF 4 ) was used.
　まず、Ｓｔｅｐ１（混合物調製工程Ｓ１）では、上記の単層カーボンナノチューブ５０ｍｇを、親水性のイオン液体であるテトラフルオロホウ酸Ｎ，Ｎ－ジエチル－Ｎ－メチル－Ｎ－（２－メトキシエチル）アンモニウム（ＤＥＭＥＢＦ４）１００ｍｇと混合し、得られた懸濁液を６時間にわたって自動粉砕システムにかけた。これにより、単層カーボンナノチューブとイオン液体との混合物（カーボンナノチューブ分散ゲル）を得た。 First, in Step 1 (mixture preparation step S1), 50 mg of the above single-walled carbon nanotubes were added to N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, which is a hydrophilic ionic liquid. (DEMEBF 4 ) was mixed with 100 mg and the resulting suspension was subjected to an automatic grinding system for 6 hours. As a result, a mixture of single-walled carbon nanotubes and ionic liquid (carbon nanotube-dispersed gel) was obtained.
　次に、Ｓｔｅｐ２（分散液調製工程Ｓ２）では、Ｓｔｅｐ１で得られたカーボンナノチューブ分散ゲル１５０ｍｇに、分散媒としての脱イオン水１０ｍｌと、ミクロフィブリルセルロース（ダイセル化学工業社製Ｃｅｌｉｓｈ、セルロースを１０％含む水性液）２００ｍｇとを順次に添加した。その後、得られた混合物をスターラーにより２５℃にて１時間にわたって撹拌し、次いでＳＭＴ社製ＵＨ－５０を用いて３０℃にて１０分間にわたって超音波処理した。これにより、単層カーボンナノチューブと、イオン液体と、ミクロフィブリルセルロースとが均一に分散した導電性セルロース組成物（ナノチューブ分散水溶液）を得た。 Next, in Step 2 (dispersion liquid preparation step S2), 150 mg of the carbon nanotube dispersion gel obtained in Step 1 is mixed with 10 ml of deionized water as a dispersion medium, microfibril cellulose (Celish manufactured by Daicel Chemical Industries, 10% cellulose) 200 mg of an aqueous liquid containing the solution was sequentially added. The resulting mixture was then stirred with a stirrer at 25 ° C. for 1 hour, and then sonicated with SMT UH-50 at 30 ° C. for 10 minutes. As a result, a conductive cellulose composition (nanotube-dispersed aqueous solution) in which single-walled carbon nanotubes, an ionic liquid, and microfibril cellulose were uniformly dispersed was obtained.
　次に、Ｓｔｅｐ３（乾燥工程Ｓ３）では、Ｓｔｅｐ２で得られたナノチューブ分散水溶液を、ポリテトラフルオロエチレン（ＰＴＦＥ）製プレートの上にドロップキャスティングし、２４時間かけて風乾した。これにより、導電性物質としてカーボンナノチューブを用いた導電紙（カーボンナノチューブ導電紙）を得た。 Next, in Step 3 (drying step S3), the nanotube-dispersed aqueous solution obtained in Step 2 was drop-cast on a polytetrafluoroethylene (PTFE) plate and air-dried over 24 hours. Thereby, conductive paper (carbon nanotube conductive paper) using carbon nanotubes as a conductive substance was obtained.
　［高導電性ポリマーを用いた導電紙の製造方法］
　次に、導電性物質として、高導電性ポリマーを用いた例を、図４を参照しつつ説明する。
　図４は、導電性物質としてＰＥＤＯＴを用いた導電紙の製造プロセスの一例を示す図である。図４中、Ｓｔｅｐ１、Ｓｔｅｐ２、及びＳｔｅｐ３は、本発明の導電紙の製造方法における混合物調製工程Ｓ１、分散液調製工程Ｓ２、及び乾燥工程Ｓ３にそれぞれ対応する。 [Method for producing conductive paper using highly conductive polymer]
Next, an example in which a highly conductive polymer is used as the conductive material will be described with reference to FIG.
FIG. 4 is a diagram illustrating an example of a process for producing conductive paper using PEDOT as a conductive substance. In FIG. 4, Step1, Step2, and Step3 correspond to the mixture preparation step S1, the dispersion preparation step S2, and the drying step S3, respectively, in the conductive paper manufacturing method of the present invention.
　本実施例では、高導電性ポリマーとして、高分子量ポリスチレンスルホン酸水溶液中で３，４－エチレンジオキシチオフェンを重合させて得られた高導電性ポリマーであるＰＥＤＯＴの水性分散液（ＴＡ　ケミカル社製Ｂａｙｔｒｏｎ　ＰＨ５００、ＰＥＤＯＴ含有量１ｗｔ％）を用いた。
　また、イオン液体として、テトラフルオロホウ酸Ｎ，Ｎ－ジエチル－Ｎ－メチル－Ｎ－（２－メトキシエチル）アンモニウム（ＤＥＭＥＢＦ４）を用いた。
　さらに、ＰＥＤＯＴの導電性を向上させる添加剤としてジメチルスルホキシド（ＤＭＳＯ）を用いた。 In this example, as a highly conductive polymer, an aqueous dispersion of PEDOT, which is a highly conductive polymer obtained by polymerizing 3,4-ethylenedioxythiophene in a high molecular weight polystyrenesulfonic acid aqueous solution (manufactured by TA Chemical Co., Ltd.). Baytron PH500, PEDOT content 1 wt%) was used.
As the ionic liquid, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate (DEMEBF 4 ) was used.
Furthermore, dimethyl sulfoxide (DMSO) was used as an additive for improving the conductivity of PEDOT.
　まず、Ｓｔｅｐ１（混合物調製工程Ｓ１）では、ＰＥＤＯＴ１％水溶液４ｇ（ＰＥＤＯＴ４０ｍｇ）を、親水性イオン液体（ＤＥＭＥＢＦ４）５０ｍｇ、及びジメチルスルホキシド（ＤＭＳＯ）２００ｍｇと混合した。これにより、ＰＥＤＯＴとイオン液体との混合物（ＰＥＤＯＴ－ＰＳＳゲル）を得た。 First, in Step 1 (mixture preparation step S1), 4 g of PEDOT 1% aqueous solution (40 mg of PEDOT) was mixed with 50 mg of hydrophilic ionic liquid (DEMEBF 4 ) and 200 mg of dimethyl sulfoxide (DMSO). As a result, a mixture of PEDOT and ionic liquid (PEDOT-PSS gel) was obtained.
　次に、Ｓｔｅｐ２（分散液調製工程Ｓ２）において、Ｓｔｅｐ１で得られたＰＥＤＯＴ－ＰＳＳゲルに、分散媒としての脱イオン水１０ｍｌと、ミクロフィブリルセルロース１００ｍｇとを順次に添加した。その後、得られた混合物を２５℃にて１時間にわたって撹拌した。これにより、ＰＥＤＯＴと、イオン液体と、ミクロフィブリルセルロースとが均一に分散した導電性セルロース組成物（ＰＥＤＯＴ－ＰＳＳゲル分散水溶液）を得た。 Next, in Step 2 (dispersion preparation step S2), 10 ml of deionized water as a dispersion medium and 100 mg of microfibril cellulose were sequentially added to the PEDOT-PSS gel obtained in Step 1. The resulting mixture was then stirred at 25 ° C. for 1 hour. As a result, a conductive cellulose composition (PEDOT-PSS gel-dispersed aqueous solution) in which PEDOT, an ionic liquid, and microfibril cellulose were uniformly dispersed was obtained.
　次に、Ｓｔｅｐ３（乾燥工程Ｓ３）において、ＰＥＤＯＴ－ＰＳＳゲル分散水溶液をドロップキャスティングによってＰＴＦＥプレート上に注ぎ、２４時間かけて風乾した。これにより、導電性物質として高導電性ポリマー（ＰＥＤＯＴ－ＰＳＳ）を用いた導電紙（ＰＥＤＯＴ－ＰＳＳ導電紙）を得た。 Next, in Step 3 (drying step S3), the PEDOT-PSS gel-dispersed aqueous solution was poured onto a PTFE plate by drop casting and air-dried over 24 hours. As a result, conductive paper (PEDOT-PSS conductive paper) using a highly conductive polymer (PEDOT-PSS) as a conductive material was obtained.
　［導電率評価］
　次に、上記カーボンナノチューブ及び高導電性ポリマーを用いた導電紙の導電率評価を行った結果について説明する。評価に際しては、上記に説明した各製造プロセスにより、セルロース含有量５～６６ｗｔ％の範囲で代えた複数種類の導電紙を作製し、それらについて導電率の測定を行った。導電率測定は高精度電源測定ユニットを用いた四端子法により行なった。 [Conductivity evaluation]
Next, the result of conducting the electrical conductivity evaluation of the conductive paper using the carbon nanotube and the highly conductive polymer will be described. In the evaluation, a plurality of types of conductive papers having a cellulose content in the range of 5 to 66 wt% were prepared by the manufacturing processes described above, and the conductivity was measured for them. The conductivity was measured by a four-terminal method using a high-accuracy power supply measurement unit.
　図５は、セルロース含有量と導電率の関係を示すグラフである。図６は、カーボンナノチューブ導電紙とＰＥＤＯＴ－ＰＳＳ導電紙の平面ＳＥＭ写真である。 FIG. 5 is a graph showing the relationship between cellulose content and electrical conductivity. FIG. 6 is a planar SEM photograph of carbon nanotube conductive paper and PEDOT-PSS conductive paper.
　本発明では、セルロースの含有量が１２ｗｔ％で、ＳＷＮＴとＤＥＮＥＢＦ４の混合比が１：２のときに、最大の導電率（７２Ｓ／ｃｍ）が得られた。本発明者が知る限り、これまでに報告されている柔らかい材料（紙もしくはポリマー）における最大値であり、以前に報告されている非絶縁紙（例えば、Yoon SH,Jin HJ,Kook MC,Pyun YR (2006) Electrically conductive bacterial cellulose by incorporation of carbon nanotubes, Biomacromolecules 7: 1280-1284）の導電率（０．１Ｓ／ｃｍ程度）よりも３桁程大きい。 In the present invention, the maximum conductivity (72 S / cm) was obtained when the cellulose content was 12 wt% and the mixing ratio of SWNT and DENEBF 4 was 1: 2. To the best of the inventors' knowledge, this is the highest reported soft material (paper or polymer), and previously reported non-insulating paper (eg Yoon SH, Jin HJ, Kook MC, Pyun YR (2006) Electrically conductive bacterial cellulose by incorporation of carbon nanotubes, Biomacromolecules 7: 1280-1284), which is about three orders of magnitude larger than the conductivity (about 0.1 S / cm).
　単層カーボンナノチューブは共有結合が強くバンドルを形成しやすいため、ポリマーや他の材料と混合したときに凝集しやすい。しかし、本発明で用いているイオン液体は、単層カーボンナノチューブの絡み合いを阻止することができる。これにより、紙の柔らかさに悪い影響を与えることなく単層カーボンナノチューブの含有量を３０ｗｔ％という大きな値にすることができ、高アスペクト比のスーパーグロースカーボンナノチューブをミクロフィブリルセルロースに均一に分散させることができた。その結果、上記のように大きな導電率を実現できた。 Since single-walled carbon nanotubes have strong covalent bonds and tend to form bundles, they tend to aggregate when mixed with polymers and other materials. However, the ionic liquid used in the present invention can prevent entanglement of single-walled carbon nanotubes. As a result, the content of the single-walled carbon nanotubes can be as large as 30 wt% without adversely affecting the softness of the paper, and the high-aspect ratio super-growth carbon nanotubes can be uniformly dispersed in the microfibril cellulose. I was able to. As a result, a large electrical conductivity was realized as described above.
　また図６に示すように、カーボンナノチューブ導電紙の場合、セルロースの含有量が４０ｗｔ％を超えると、厚い多孔性の導電紙となった。一方、セルロースの含有量が１０ｗｔ％未満のときには、多孔性で脆いカーボンナノチューブ導電紙となった。セルロース含有量が１２ｗｔ％のものは、最も表面が滑らかであり、この条件が導電率が最も高いことから、単層カーボンナノチューブが最も均一に分散されていると考えられる。 Also, as shown in FIG. 6, in the case of carbon nanotube conductive paper, when the cellulose content exceeded 40 wt%, a thick porous conductive paper was obtained. On the other hand, when the cellulose content was less than 10 wt%, the carbon nanotube conductive paper was porous and brittle. When the cellulose content is 12 wt%, the surface is the smoothest, and since this condition has the highest conductivity, it is considered that the single-walled carbon nanotubes are most uniformly dispersed.
　一方、ＰＥＤＯＴ－ＰＳＳ導電紙の場合には、図６に示すように、セルロースの含有量が増えるにつれて表面は粗くなった。セルロースの含有量が５０ｗｔ％を超えると厚く多孔性のＰＥＤＯＴ－ＰＳＳ導電紙となった。セルロースの含有量が５ｗｔ％未満のときには脆いＰＥＤＯＴ－ＰＳＳ導電紙となった。本発明では、セルロースの含有量が１０ｗｔ％で、ＰＥＤＯＴとＤＥＮＥＢＦ４の混合比が４：５のときに、最大の導電率（７５Ｓ／ｃｍ）が得られた。 On the other hand, in the case of PEDOT-PSS conductive paper, as shown in FIG. 6, the surface became rough as the cellulose content increased. When the cellulose content exceeded 50 wt%, a thick and porous PEDOT-PSS conductive paper was obtained. When the cellulose content was less than 5 wt%, a brittle PEDOT-PSS conductive paper was obtained. In the present invention, the maximum conductivity (75 S / cm) was obtained when the cellulose content was 10 wt% and the mixing ratio of PEDOT and DENEBF 4 was 4: 5.
　ＰＥＤＯＴ－ＰＳＳ導電紙の導電率と柔らかさに対してイオン液体が重要な役割を果たしていることが認められた。セルロースとイオン液体なしにＰＥＤＯＴを用いて形成した膜は、１００Ｓ／ｃｍを超える大きな導電率を示した。しかし、この膜は非常に脆く、曲げ応力を膜に加えると必ず電気的、機械的な劣化が起こった。また、セルロースを添加したＰＥＤＯＴを用いて作製した紙でも相変わらず脆く、柔らかさは改善されなかった。しかし、十分な量のイオン液体をＰＥＤＯＴに添加すると、ＰＥＤＯＴはゲル状になり、セルロースに一様に分散した。得られたＰＥＤＯＴ－ＰＳＳ導電紙は導電率が大きいだけでなく、可撓性と柔らかさにも優れていた。 It was found that the ionic liquid plays an important role in the conductivity and softness of the PEDOT-PSS conductive paper. A film formed using PEDOT without cellulose and ionic liquid showed a high conductivity exceeding 100 S / cm. However, this film was very brittle, and whenever a bending stress was applied to the film, electrical and mechanical deterioration occurred. Moreover, even the paper produced using PEDOT to which cellulose was added was still brittle and the softness was not improved. However, when a sufficient amount of ionic liquid was added to PEDOT, PEDOT became a gel and was uniformly dispersed in cellulose. The obtained PEDOT-PSS conductive paper not only had high electrical conductivity, but also excellent flexibility and softness.
　［曲げ耐性評価］
　図７は、本実施例で作製したカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙を曲げたときの曲げ半径に対する抵抗値の変化を示すグラフである。測定は、正確な機械式ステージを備えた応力装置を用いて導電紙を曲げ、曲げた後の抵抗値を測定することにより行った。 [Bending resistance evaluation]
FIG. 7 is a graph showing a change in resistance value with respect to a bending radius when the carbon nanotube conductive paper and the PEDOT-PSS conductive paper produced in this example are bent. The measurement was performed by bending the conductive paper using a stress device equipped with an accurate mechanical stage and measuring the resistance value after bending.
　図７に示すように、カーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙のいずれにおいても、曲げたときの抵抗値はほぼ一定であり、抵抗値の変動幅は、完全に折り曲げた（曲げ半径が１００μｍ未満）ときでも無視できる程度に小さい。このことから、本発明の導電紙が大きな機械的可撓性を有しており、曲げ応力下での耐久性に優れていることが確認された。 As shown in FIG. 7, in both the carbon nanotube conductive paper and the PEDOT-PSS conductive paper, the resistance value when bent is almost constant, and the fluctuation range of the resistance value is completely bent (the bending radius is 100 μm). Is less than negligible. From this, it was confirmed that the conductive paper of the present invention has great mechanical flexibility and is excellent in durability under bending stress.
　従来の紙またはプラスチックシートの表面に金属薄膜を形成した導電紙や導電性シートでは、折り曲げたときに金属薄膜と紙／プラスチックの界面に応力が作用し金属薄膜が容易に破断されていた。これに対して、本発明では、導電性セルロースを互いに絡み合わせて導電紙を構成しているため、大きな導電率と大きな機械的可撓性／耐久性の両方を同時に実現することができる。 In a conventional conductive paper or conductive sheet in which a metal thin film is formed on the surface of a paper or plastic sheet, when the metal paper is folded, a stress acts on the interface between the metal thin film and the paper / plastic, and the metal thin film is easily broken. On the other hand, in the present invention, the conductive cellulose is entangled with each other to form the conductive paper, so that both high electrical conductivity and high mechanical flexibility / durability can be realized at the same time.
　また、ＰＥＤＯＴ－ＰＳＳ導電紙において優れた曲げ耐性が得られることは注目すべき結果である。イオン液体及びミクロフィブリルセルロースを用いずに作製された従来のＰＥＤＯＴ膜は、非常に脆いために曲げ応力を加えることができなかった。これに対して、本実施例のＰＥＤＯＴ－ＰＳＳ導電紙は、完全に折り曲げることが可能であり、従来のＰＥＤＯＴ膜とは著しく異なる性質を有している。これは、イオン液体とＰＥＤＯＴの混合物がゲルを形成し、ミクロフィブリルセルロースに一様に分散させることができたためであると考えられる。 Also, it is a remarkable result that excellent bending resistance is obtained in the PEDOT-PSS conductive paper. A conventional PEDOT film prepared without using an ionic liquid and microfibril cellulose cannot be subjected to bending stress because it is very brittle. On the other hand, the PEDOT-PSS conductive paper of this embodiment can be bent completely and has properties that are significantly different from those of conventional PEDOT films. This is considered to be because the mixture of the ionic liquid and PEDOT formed a gel and could be uniformly dispersed in the microfibril cellulose.
　［電力伝送評価］
　図８は、本実施例で作製したカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙の伝送特性を測定した結果を示すグラフである。銅配線における測定結果も比較のために示してある。
　測定は、ネットワーク分析装置（Ａｇｉｌｅｎｔ社製４３９５Ａ）を用いて行なった。測定に用いたカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙の長さ、幅、厚さは、それぞれ、３０ｍｍ、５ｍｍ、７０μｍとした。 [Electric power transmission evaluation]
FIG. 8 is a graph showing the results of measuring the transmission characteristics of the carbon nanotube conductive paper and PEDOT-PSS conductive paper prepared in this example. Measurement results for copper wiring are also shown for comparison.
The measurement was performed using a network analyzer (Agilent 4395A). The length, width, and thickness of the carbon nanotube conductive paper and PEDOT-PSS conductive paper used for the measurement were 30 mm, 5 mm, and 70 μm, respectively.
　図８に示すように、カーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙の伝送損失は、１００ＭＨｚまで－２ｄＢ以内であった。銅配線の伝送損失と比較しても差は３７％未満であった。
　本発明の導電紙の別の重要な利点は、紙の中を流れる電流がイオンではなく電子に依存していることにある。これにより、図示のようにＭＨｚ領域で優れた電気的特性を実現することができる。 As shown in FIG. 8, the transmission loss of the carbon nanotube conductive paper and the PEDOT-PSS conductive paper was within −2 dB up to 100 MHz. Even when compared with the transmission loss of the copper wiring, the difference was less than 37%.
Another important advantage of the conductive paper of the present invention is that the current flowing through the paper is dependent on electrons rather than ions. As a result, excellent electrical characteristics can be realized in the MHz region as shown.
　ここで、図９はカーボンナノチューブ導電紙とＰＥＤＯＴ－ＰＳＳ導電紙の電気的特性を示すグラフである。図９（ａ）は伝送特性を示すグラフであり、（ｂ）は温度と導電率との関係を示すグラフである。
　図９（ａ）に示すように、カーボンナノチューブ導電紙を通じて伝送できる最大電力は３５Ｗであり、ＰＥＤＯＴ－ＰＳＳ導電紙を通じて伝送できる最大電力は３８Ｗであった。伝送特性の測定は、１３．５６ＭＨｚの電力発生装置（ＵＬＶＡＣ社製ＲＧＮ－１３０２）と、伝送される電力を測定するためのスペクトル分析装置（Ａｇｉｌｅｎｔ社製４３９５Ａ）を用いて行なった。
　また、図９（ｂ）に示すように、ばらつきはあるものの、カーボンナノチューブ導電紙、ＰＥＤＯＴ－ＰＳＳ導電紙のいずれも、３００℃まで加熱した後も優れた導電率を保持しており、耐熱性にも優れていることが確認された。 Here, FIG. 9 is a graph showing electrical characteristics of the carbon nanotube conductive paper and the PEDOT-PSS conductive paper. FIG. 9A is a graph showing transmission characteristics, and FIG. 9B is a graph showing the relationship between temperature and conductivity.
As shown in FIG. 9A, the maximum power that can be transmitted through the carbon nanotube conductive paper was 35 W, and the maximum power that could be transmitted through the PEDOT-PSS conductive paper was 38 W. Transmission characteristics were measured using a 13.56 MHz power generator (ULGN RGN-1302) and a spectrum analyzer (Agilent 4395A) for measuring the transmitted power.
In addition, as shown in FIG. 9B, although there are variations, both the carbon nanotube conductive paper and the PEDOT-PSS conductive paper retain excellent conductivity even after being heated to 300 ° C. Also confirmed to be excellent.
　［リサイクル性評価］
　カーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙は、いずれも水を用いてリサイクルすることができる。これらの導電紙を水に浸すと、導電性セルロース間の水素結合が水によって弱くなる。その結果、紙を形成している導電性セルロースが急速に水に溶解し、導電性セルロースが分散した分散液に戻る。その後、得られた分散液を乾燥させることで、精製などの追加の工程を経ることなしに導電紙を形成することができる。かかる導電紙の再生は、印刷により形成された回路パターンに対しても、全く同様にして行うことができる。 [Recyclability evaluation]
Both the carbon nanotube conductive paper and the PEDOT-PSS conductive paper can be recycled using water. When these conductive papers are immersed in water, hydrogen bonds between the conductive celluloses are weakened by water. As a result, the conductive cellulose forming the paper rapidly dissolves in water and returns to the dispersion in which the conductive cellulose is dispersed. Thereafter, by drying the obtained dispersion, conductive paper can be formed without additional steps such as purification. Such regeneration of the conductive paper can be performed in exactly the same manner for a circuit pattern formed by printing.
　図１０は、本実施例で作製したカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙をリサイクルしたときの導電率の変化を示したグラフである。図１１は、リサイクル後のカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙の平面ＳＥＭ写真である。
　リサイクル方法は、まず、カーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙を、３０℃の水中で１時間攪拌してこれらの導電紙を溶解させ、カーボンナノチューブ分散水溶液及びＰＥＤＯＴ－ＰＳＳ分散ゲル水溶液とする。その後、得られた分散液をドロップキャスティングによって再びＰＴＦＥプレートの上に注ぎ、２４時間かけて風乾させ、それぞれカーボンナノチューブ導電紙及びＰＥＤＯＴ－ＰＳＳ導電紙として再生する。以上の工程を１サイクルとして、図１０に示すように１０回のリサイクルを行い、リサイクルする度に導電率の測定を行った。 FIG. 10 is a graph showing the change in conductivity when the carbon nanotube conductive paper and PEDOT-PSS conductive paper produced in this example are recycled. FIG. 11 is a planar SEM photograph of carbon nanotube conductive paper and PEDOT-PSS conductive paper after recycling.
In the recycling method, first, carbon nanotube conductive paper and PEDOT-PSS conductive paper are stirred in water at 30 ° C. for 1 hour to dissolve these conductive papers to obtain a carbon nanotube dispersed aqueous solution and a PEDOT-PSS dispersed gel aqueous solution. After that, the obtained dispersion is again poured onto the PTFE plate by drop casting, air-dried for 24 hours, and regenerated as carbon nanotube conductive paper and PEDOT-PSS conductive paper, respectively. The above process was set as one cycle, and 10 times of recycling was performed as shown in FIG. 10, and the conductivity was measured every time it was recycled.
　図１０に示すように、リサイクル回数が増えるにしたがって導電率はやや低下する傾向にあるものの、電気的特性の著しい低下は観察できなかった。また図１１に示すように、リサイクル１０回後においても、導電紙の状態には大きな変化がないことが観察された。
　このように、極めて容易に、かつ、極めて多数回にわたってリサイクルが可能であることは、省資源、環境保護の観点からばかりでなく、電気・電子回路の作成効率の観点からも極めて多大な利点をもたらすものである。また、このように加熱プロセスまたは高エネルギープロセスを必要としないリサイクル可能な導体はこれまで報告されていない新規な導電性材料である。 As shown in FIG. 10, although the conductivity tends to decrease slightly as the number of recycling increases, no significant decrease in electrical characteristics could be observed. Further, as shown in FIG. 11, it was observed that there was no significant change in the state of the conductive paper even after 10 recycles.
In this way, being able to recycle very easily and extremely many times is extremely advantageous not only from the viewpoint of resource saving and environmental protection, but also from the viewpoint of the efficiency of creating electrical and electronic circuits. It is what brings. Also, recyclable conductors that do not require heating or high energy processes are novel conductive materials that have not been reported so far.
　［親水性／疎水性導電紙比較］
　導電紙は、親水性イオン液体を用いて作製すると親水性となり、親水性イオン液体の代わりに疎水性イオン液体を用いると疎水性となる。 [Comparison of hydrophilic / hydrophobic conductive paper]
The conductive paper becomes hydrophilic when made using a hydrophilic ionic liquid, and becomes hydrophobic when a hydrophobic ionic liquid is used instead of the hydrophilic ionic liquid.
　本例では、疎水性の導電紙を作るため、先のカーボンナノチューブ導電紙の製造工程において、ＤＥＭＥＴＦＳＩを疎水性イオン液体として使用し、カーボンナノチューブ分散ゲルを分散させるのにエタノールを使用して疎水性のカーボンナノチューブ導電紙を作製した。疎水性カーボンナノチューブ導電紙における単層カーボンナノチューブとイオン液体（ＤＥＭＥＴＦＳＩ）の含有量の比は１：１とした。
　また同様にして、先のＰＥＤＯＴ－ＰＳＳ導電紙の製造工程において、ＤＥＭＥＴＦＳＩを疎水性イオン液体として使用し、分散媒としてエタノールを使用して疎水性のＰＥＤＯＴ－ＰＳＳ導電紙を作製した。 In this example, in order to make hydrophobic conductive paper, in the previous manufacturing process of carbon nanotube conductive paper, DEMETFSI was used as the hydrophobic ionic liquid, and ethanol was used to disperse the carbon nanotube dispersion gel. A carbon nanotube conductive paper was prepared. The ratio of the content of the single-walled carbon nanotube and the ionic liquid (DEMETFSI) in the hydrophobic carbon nanotube conductive paper was 1: 1.
Similarly, a hydrophobic PEDOT-PSS conductive paper was prepared using DEMETFSI as a hydrophobic ionic liquid and ethanol as a dispersion medium in the previous manufacturing process of PEDOT-PSS conductive paper.
　図１２（ａ）は、親水性のカーボンナノチューブ導電紙と疎水性のカーボンナノチューブ導電紙とについて、セルロース含有量に対する導電率の変化を対比したグラフである。図１２（ｂ）は、親水性のＰＥＤＯＴ－ＰＳＳ導電紙と疎水性のＰＥＤＯＴ－ＰＳＳ導電紙とについて、セルロース含有量に対する導電率の変化を対比したグラフである。 FIG. 12 (a) is a graph comparing the change in conductivity with respect to the cellulose content for hydrophilic carbon nanotube conductive paper and hydrophobic carbon nanotube conductive paper. FIG. 12 (b) is a graph comparing the change in conductivity with respect to the cellulose content for hydrophilic PEDOT-PSS conductive paper and hydrophobic PEDOT-PSS conductive paper.
　図１２に示すように、カーボンナノチューブ導電紙、ＰＥＤＯＴ－ＰＳＳ導電紙のいずれについても、親水性と疎水性の間で導電率にはほとんど差異がない。より詳しくは、疎水性のカーボンナノチューブ導電紙の導電率は６７Ｓ／ｃｍであり、そのときの単層カーボンナノチューブとＤＥＭＥＴＦＳＩの含有量の比は１：１である。一方、疎水性のＰＥＤＯＴ－ＰＳＳ導電紙の導電率は５５Ｓ／ｃｍであり、そのときのＰＥＤＯＴとＤＥＭＥＴＦＳＩの含有量の比は２：３である。 As shown in FIG. 12, there is almost no difference in electrical conductivity between hydrophilic and hydrophobic in both carbon nanotube conductive paper and PEDOT-PSS conductive paper. More specifically, the conductivity of the hydrophobic carbon nanotube conductive paper is 67 S / cm, and the content ratio of the single-walled carbon nanotube and DEMETFSI at that time is 1: 1. On the other hand, the conductivity of the hydrophobic PEDOT-PSS conductive paper is 55 S / cm, and the content ratio of PEDOT and DEMETFSI at that time is 2: 3.
　次に、図１３は、親水性及び疎水性のカーボンナノチューブ導電紙と、親水性及び疎水性のカーボンナノチューブ導電紙を、それぞれ水中に浸したときの抵抗値の変化を示すグラフである。
　図１３に示すように、疎水性のカーボンナノチューブ導電紙は、水に浸しても抵抗値がまったく変化しなかった。これに対して、親水性のカーボンナノチューブ導電紙は、浸漬直後から抵抗値が上がり始める。これは、親水性のカーボンナノチューブ導電紙はセルロースが数秒のうちに水に溶け始めるためである。 Next, FIG. 13 is a graph showing changes in resistance values when the hydrophilic and hydrophobic carbon nanotube conductive paper and the hydrophilic and hydrophobic carbon nanotube conductive paper are immersed in water, respectively.
As shown in FIG. 13, the resistance value of the hydrophobic carbon nanotube conductive paper did not change even when immersed in water. On the other hand, the resistance value of the hydrophilic carbon nanotube conductive paper starts to increase immediately after immersion. This is because the hydrophilic carbon nanotube conductive paper begins to dissolve in water within a few seconds.
　また、導電率が大きな（６０Ｓ／ｃｍ）親水性のカーボンナノチューブ導電紙の結果と、導電率が小さい（５Ｓ／ｃｍ）親水性のカーボンナノチューブ導電紙の結果とを比較することは興味深い。両者とも、セルロースの含有量によって導電率が変化しているが、抵抗値の変化は導電率が小さいカーボンナノチューブ導電紙の方が著しく大きい。これは、導電率の小さいカーボンナノチューブ導電紙は、セルロース含有量が多いために多孔性の膜になっており、より溶解しやすいためである。 It is also interesting to compare the results of hydrophilic carbon nanotube conductive paper with high conductivity (60 S / cm) and the results of hydrophilic carbon nanotube conductive paper with low conductivity (5 S / cm). In both cases, the conductivity changes depending on the cellulose content, but the change in the resistance value is significantly larger in the carbon nanotube conductive paper having a lower conductivity. This is because the carbon nanotube conductive paper having a low conductivity is a porous film because of its high cellulose content, and is more easily dissolved.
　一方、疎水性のＰＥＤＯＴ－ＰＳＳ導電紙も、水に浸しても抵抗値はさほど上昇しないが、長時間浸漬すると抵抗値が上がり始める。これは、ＰＥＤＯＴ－ＰＳＳが水溶性であり、水中で不安定であることに起因する。これに対して親水性のＰＥＤＯＴ－ＰＳＳ導電紙は、カーボンナノチューブ導電紙と同様に、浸漬直後から抵抗値が上がり始めるが、抵抗値の上昇率がカーボンナノチューブ導電紙よりもかなり大きい。これは、セルロースとＰＥＤＯＴ－ＰＳＳの両方が水溶性であるためである。 On the other hand, even when hydrophobic PEDOT-PSS conductive paper is immersed in water, the resistance value does not increase so much, but when it is immersed for a long time, the resistance value starts to increase. This is due to the fact that PEDOT-PSS is water soluble and unstable in water. In contrast, the hydrophilic PEDOT-PSS conductive paper, like the carbon nanotube conductive paper, starts to increase in resistance immediately after immersion, but the increase rate of the resistance value is considerably larger than that of the carbon nanotube conductive paper. This is because both cellulose and PEDOT-PSS are water soluble.
　［カーボンナノチューブの長さによる特性比較］
　図１４は、導電性物質としてスーパーグロース法で作製した単層カーボンナノチューブを用いたカーボンナノチューブ導電紙（図中に「ＳＧ」と示す）と、市販のＨｉＰｃｏ法で作製された単層カーボンナノチューブを用いたカーボンナノチューブ導電紙（図中に「ＨｉＰｃｏ」と示す）との比較を示す図である。 [Characteristic comparison by length of carbon nanotube]
FIG. 14 shows a carbon nanotube conductive paper (indicated as “SG” in the figure) using a single-walled carbon nanotube produced by a super-growth method as a conductive substance, and a single-walled carbon nanotube produced by a commercially available HiPco method. It is a figure which shows the comparison with the used carbon nanotube conductive paper (it shows as "HiPco" in a figure).
　図１４に示すように、スーパーグロース法による単層カーボンナノチューブを用いたカーボンナノチューブ導電紙（ＳＧ）は、ＨｉＰｃｏ法による単層カーボンナノチューブを用いたカーボンナノチューブ導電紙（ＨｉＰｃｏ）よりもはるかに大きな導電率を示した。導電性物質として市販のＨｉＰｃｏ法による単層カーボンナノチューブを用いたカーボンナノチューブ導電紙では、導電率が５．７Ｓ／ｃｍであり、従来知られている導電紙と比べれば十分大きい導電率であるが、スーパーグロース法による単層カーボンナノチューブを用いた導電紙はさらに１０倍以上の導電率が得られた。スーパーグロース法による単層カーボンナノチューブの大きなアスペクト比は、大きな導電率を得る上で重要であることが分かる。 As shown in FIG. 14, the carbon nanotube conductive paper (SG) using single-walled carbon nanotubes by the super-growth method has a much larger conductive property than the carbon nanotube conductive paper (HiPco) using single-walled carbon nanotubes by the HiPco method. Showed the rate. The carbon nanotube conductive paper using single-walled carbon nanotubes by a commercially available HiPco method as the conductive material has a conductivity of 5.7 S / cm, which is sufficiently higher than that of conventionally known conductive paper. The conductive paper using the single-walled carbon nanotubes by the super-growth method further obtained a conductivity of 10 times or more. It can be seen that a large aspect ratio of single-walled carbon nanotubes by the super-growth method is important in obtaining a large electrical conductivity.
　さらに、スーパーグロース法による単層カーボンナノチューブを用いた導電紙の表面は、ＨｉＰｃｏ法による単層カーボンナノチューブを用いた導電紙の表面よりもはるかに滑らかであった。これは、スーパーグロース法による単層カーボンナノチューブはセルロースの中に一様に分散させうることを意味している。 Furthermore, the surface of the conductive paper using single-walled carbon nanotubes by the super-growth method was much smoother than the surface of the conductive paper using single-walled carbon nanotubes by the HiPco method. This means that single-walled carbon nanotubes obtained by the super-growth method can be uniformly dispersed in cellulose.
　［電子デバイス］
　図１５及び図１６は専ら紙からなるタッチセンサシステムを示す図である。
　図１５（ａ）は紙配線によって鉛直方向と水平方向に接続された８×８個の導電紙キャパシタを含む紙のみからなるタッチセンサの写真である。図１５（ｂ）はタッチセンサの回路図である。図１６（ａ）は、図１５に示すタッチセンサの２×２セルの概略図である。図１６（ｂ）は時間の関数としてのタッチセンサのセルの容量変化を示す説明図である。 [Electronic device]
15 and 16 are diagrams showing a touch sensor system made entirely of paper.
FIG. 15A is a photograph of a touch sensor made of only paper including 8 × 8 conductive paper capacitors connected in the vertical and horizontal directions by paper wiring. FIG. 15B is a circuit diagram of the touch sensor. FIG. 16A is a schematic diagram of 2 × 2 cells of the touch sensor shown in FIG. FIG. 16B is an explanatory diagram showing the change in the capacity of the cell of the touch sensor as a function of time.
　図１５及び図１６に示すように、タッチセンサ１００は、縦横に延在する導電紙配線１０２と、導電紙配線１０２の交差部に対応して形成された導電紙キャパシタ１０１（サイズ：５×５ｍｍ２）とを備えている。マトリクス状に配列された複数の導電紙キャパシタ１０１がタッチセンサ１００の個々のセルを構成している。 As shown in FIGS. 15 and 16, the touch sensor 100 includes a conductive paper wiring 102 extending vertically and horizontally, and a conductive paper capacitor 101 (size: 5 × 5 mm) formed corresponding to the intersection of the conductive paper wiring 102. 2 ). A plurality of conductive paper capacitors 101 arranged in a matrix form individual cells of the touch sensor 100.
　図１６（ａ）に示すように、タッチセンサ１００は、厚さ１５μｍの絶縁紙１０３の両面に、導電紙パターン１０５が形成された構成を備える。絶縁紙１０３の図示上面に形成された導電紙パターン１０５は、矩形状の電極１０１ａと導電紙配線（ビット線）１０２ａとを有する。絶縁紙１０３の図示下面に形成された導電紙パターン１０５は、矩形状の電極１０１ｂと導電紙配線１０２ｂ（ワード線）とを有する。互いに対向して配置された電極１０１ａ及び電極１０１ｂと、これらの間に挟まれた絶縁紙１０３とが、導電紙キャパシタ１０１を構成している。 As shown in FIG. 16A, the touch sensor 100 has a configuration in which conductive paper patterns 105 are formed on both surfaces of an insulating paper 103 having a thickness of 15 μm. The conductive paper pattern 105 formed on the upper surface of the insulating paper 103 has a rectangular electrode 101a and a conductive paper wiring (bit line) 102a. The conductive paper pattern 105 formed on the lower surface of the insulating paper 103 has a rectangular electrode 101b and a conductive paper wiring 102b (word line). The electrode 101a and the electrode 101b arranged to face each other and the insulating paper 103 sandwiched therebetween constitute the conductive paper capacitor 101.
　そして、図１６（ａ）に示すように、タッチセンサ１００のセル（導電紙キャパシタ１０１）の１つに指で触れると、図１６（ｂ）に示すように、対応するセル（導電紙キャパシタ１０１）の容量が、例えば４５ｐＦから１５０ｐＦへと変化する。これにより、タッチセンサ１００上の指が触れた位置を検出することができる。タッチセンサ１００の応答時間は１００ミリ秒未満であり、この高い感度と高速応答は、本発明の導電紙の大きな導電率をフルに活用したことで実現できたものである。 When a finger touches one of the cells (conductive paper capacitor 101) of the touch sensor 100 as shown in FIG. 16 (a), the corresponding cell (conductive paper capacitor 101) is shown in FIG. 16 (b). ) Changes from 45 pF to 150 pF, for example. Thereby, the position touched by the finger on the touch sensor 100 can be detected. The response time of the touch sensor 100 is less than 100 milliseconds, and this high sensitivity and high-speed response can be realized by fully utilizing the large conductivity of the conductive paper of the present invention.
　本発明によれば、十分な導電性と弾性とを有する導電紙及び導電性セルロース組成物を提供することができる。これらの導電紙及び導電性セルロース組成物は、種々の物品の導電性部材に好適に用いることができ、特に電子デバイスに好適に用いることができる。
　また本発明の導電紙は、通常の紙と同様に容易にリサイクルが可能であり、省資源、環境保護の観点からばかりでなく、電気・電子回路の作成効率の観点からも極めて多大な利点をもたらすものである。 According to the present invention, a conductive paper and a conductive cellulose composition having sufficient conductivity and elasticity can be provided. These conductive paper and conductive cellulose composition can be suitably used for conductive members of various articles, and can be particularly suitably used for electronic devices.
In addition, the conductive paper of the present invention can be easily recycled in the same way as ordinary paper, and has extremely great advantages not only from the viewpoint of resource saving and environmental protection, but also from the viewpoint of the efficiency of creating electrical and electronic circuits. It is what brings.

Claims (21)

  1. 　セルロースと導電性物質とが混和した導電性セルロースを有することを特徴とする導電紙。 Conductive paper comprising conductive cellulose mixed with cellulose and conductive material.
  2. 　イオン液体を含む請求項１に記載の導電紙。 The conductive paper according to claim 1, comprising an ionic liquid.
  3. 　液体に溶かして再生可能である請求項１又は２に記載の導電紙。 The conductive paper according to claim 1 or 2, which is recyclable by being dissolved in a liquid.
  4. 　導電率が１Ｓ／ｃｍ以上である請求項１から３のいずれか１項に記載の導電紙。 The conductive paper according to any one of claims 1 to 3, wherein the electrical conductivity is 1 S / cm or more.
  5. 　前記導電性物質がカーボンナノチューブである請求項１から４のいずれか１項に記載の導電紙。 The conductive paper according to any one of claims 1 to 4, wherein the conductive substance is a carbon nanotube.
  6. 　前記カーボンナノチューブの長さが１μｍ以上１０ｃｍ以下である請求項５に記載の導電紙。 The conductive paper according to claim 5, wherein the carbon nanotube has a length of 1 μm to 10 cm.
  7. 　前記導電性物質が導電性ポリマーである請求項１から４のいずれか１項に記載の導電紙。 The conductive paper according to any one of claims 1 to 4, wherein the conductive substance is a conductive polymer.
  8. 　前記イオン液体が親水性である請求項１から７のいずれか１項に記載の導電紙。 The conductive paper according to any one of claims 1 to 7, wherein the ionic liquid is hydrophilic.
  9. 　前記イオン液体が疎水性である請求項１から７のいずれか１項に記載の導電紙。 The conductive paper according to any one of claims 1 to 7, wherein the ionic liquid is hydrophobic.
  10. 　他の導電性物質が混在している請求項１から９のいずれか１項に記載の導電紙。 The conductive paper according to any one of claims 1 to 9, wherein another conductive substance is mixed.
  11. 　セルロースと導電性物質とが混和した導電性セルロースを有することを特徴とする導電性セルロース組成物。 A conductive cellulose composition comprising conductive cellulose mixed with cellulose and a conductive substance.
  12. 　イオン液体を含む請求項１１に記載の導電性セルロース組成物。 The conductive cellulose composition according to claim 11 containing an ionic liquid.
  13. 　他の導電性物質が混在している請求項１１又は１２に記載の導電性セルロース組成物。 The conductive cellulose composition according to claim 11 or 12, wherein other conductive substances are mixed.
  14. 　ペースト状、又はゲル状、又は液状であることを特徴とする請求項１１から１３のいずれか１項に記載の導電性セルロース組成物。 The conductive cellulose composition according to any one of claims 11 to 13, wherein the conductive cellulose composition is paste, gel, or liquid.
  15. 　請求項１から１０のいずれか１項に記載の導電紙、又は請求項１１から１４のいずれか１項に記載の導電性セルロース組成物を備えた物品。 An article comprising the conductive paper according to any one of claims 1 to 10, or the conductive cellulose composition according to any one of claims 11 to 14.
  16. 　請求項１から１０のいずれか１項に記載の導電紙、又は請求項１１から１４のいずれか１項に記載の導電性セルロース組成物を備えた電子デバイス。 An electronic device comprising the conductive paper according to any one of claims 1 to 10, or the conductive cellulose composition according to any one of claims 11 to 14.
  17. 　イオン液体と導電性物質との混合物を調製する工程１と、
    　前記混合物にセルロースを分散させて分散液を調製する工程２と、
    　前記分散液を乾燥させる工程３と、
    　を有することを特徴とする導電紙の製造方法。     Preparing a mixture of an ionic liquid and a conductive material 1;
    Step 2 of preparing a dispersion by dispersing cellulose in the mixture;
    Step 3 of drying the dispersion;
    A method for producing a conductive paper, comprising:
  18. 　前記分散液の乾燥物から、前記イオン液体を除去する工程４、をさらに有する請求項１７に記載の導電紙の製造方法。 The method for producing conductive paper according to claim 17, further comprising a step 4 of removing the ionic liquid from the dried product of the dispersion.
  19. 　前記イオン液体が親水性である場合に、前記分散液を調製する工程で分散媒として水を添加する請求項１７又は１８に記載の導電紙の製造方法。 The method for producing conductive paper according to claim 17 or 18, wherein water is added as a dispersion medium in the step of preparing the dispersion when the ionic liquid is hydrophilic.
  20. 　前記イオン液体が疎水性である場合に、前記分散液を調製する工程で水以外の分散媒を添加する請求項１７又は１８に記載の導電紙の製造方法。 The method for producing conductive paper according to claim 17 or 18, wherein when the ionic liquid is hydrophobic, a dispersion medium other than water is added in the step of preparing the dispersion.
  21. 　イオン液体と導電性物質との混合物を調製する工程１と、
    　前記混合物にセルロースを分散させて分散液を調製する工程２と、
    　を有することを特徴とする導電性セルロース組成物の製造方法。     Preparing a mixture of an ionic liquid and a conductive material 1;
    Step 2 of preparing a dispersion by dispersing cellulose in the mixture;
    A process for producing a conductive cellulose composition, comprising:
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