Method for producing carbon-nanotube-containing film

Abstract

This method for producing a carbon-nanotube-containing film 1 comprises a first step for preparing a carbon nanotube dispersion 12, a second step for rolling the carbon nanotube dispersion 12 between a first sheet 11 and a second sheet 13, a third step for drying the rolled carbon nanotube dispersion 12 to create a dry film 14 containing carbon nanotubes, and a fourth step for cutting the dry film 14.

Description

Method for producing carbon nanotube-containing film

[0001] The present invention relates to a method for producing a carbon nanotube-containing film.

[0002] A method for producing a CNT spun yarn has been proposed (see Patent Document 1 below), in which a CNT dispersant containing dispersed carbon nanotubes (CNTs) is discharged into an aggregating liquid in the form of threads to produce an agglomerate of the CNT dispersant (spun CNTs), and the resulting spun CNTs are dried to produce a CNT spun yarn.

[0003] International Publication No. 2018 / 047882

[0004] According to the method for producing CNT spun yarn described in Patent Document 1, a CNT dispersant is aggregated in an aggregating liquid.

[0005] Therefore, it is difficult to reduce the time required for the CNT dispersant to aggregate, making it difficult to mass-produce CNT spun yarn.

[0006] The present invention provides a method for producing a carbon nanotube-containing film that can improve production efficiency.

[0007] The present invention [1] includes a method for producing a carbon nanotube-containing film, comprising: a first step of preparing a carbon nanotube dispersion containing 1 mass % or more of carbon nanotubes and a dispersion medium; a second step of rolling the carbon nanotube dispersion between a first sheet that supports the carbon nanotube dispersion and a second sheet that covers the carbon nanotube dispersion; a third step of drying the rolled carbon nanotube dispersion to produce a dry film containing carbon nanotubes; and a fourth step of cutting the dry film.

[0008] According to this method, a carbon nanotube dispersion containing 1% by mass or more of carbon nanotubes is rolled and dried, and the resulting dried film is cut.

[0009] Therefore, a dry film containing carbon nanotubes can be produced by the simple process of rolling and drying the carbon nanotube dispersion, without undergoing a process of aggregating the carbon nanotube dispersion in an aggregating liquid.

[0010] Then, the resulting dried film is cut into a simple process, whereby a carbon nanotube-containing film having a desired shape can be obtained.

[0011] Therefore, the production efficiency of the carbon nanotube-containing film can be improved.

[0012] The present invention [2] includes the method for producing a carbon nanotube-containing film according to the above [1], wherein at least one of the first sheet and the second sheet is permeable to the dispersion medium.

[0013] According to this method, at least one of the first sheet and the second sheet is permeable to the dispersion medium, so that the dispersion medium in the carbon nanotube dispersion liquid can be absorbed by at least one of the first sheet and the second sheet.

[0014] Therefore, when the carbon nanotube dispersion liquid is rolled in the second step, the carbon nanotube dispersion liquid can be prevented from flowing excessively between the first sheet and the second sheet.

[0015] Furthermore, before drying the carbon nanotube dispersion in the third step, the amount of the dispersion medium in the carbon nanotube dispersion can be reduced.

[0016] Therefore, the carbon nanotube dispersion liquid can be dried in a state where the concentration of carbon nanotubes in the carbon nanotube dispersion liquid is increased.

[0017] As a result, the strength and electrical conductivity of the carbon nanotube-containing film can be improved, and the drying time can be shortened when drying the carbon nanotube dispersion in the third step.

[0018] The present invention [3] includes the method for producing a carbon nanotube-containing film according to the above [1] or [2], wherein the second sheet is peeled off from the carbon nanotube dispersion liquid after the second step and before the third step.

[0019] The present invention [4] includes the method for producing a carbon nanotube-containing film according to any one of the above [1] to [3], wherein the drying temperature in the third step is less than 150°C.

[0020] According to this method, a dried film can be obtained while maintaining the shape of the coating film of the carbon nanotube dispersion.

[0021] The present invention [5] includes the method for producing a carbon nanotube-containing film according to any one of the above [1] to [4], wherein the boiling point of the dispersion medium at 1 atmospheric pressure is 100° C. or lower.

[0022] The present invention [6] includes the method for producing a carbon nanotube-containing film according to any one of the above [1] to [5], wherein in the fourth step, the dry film is cut with a slitting device.

[0023] The present invention [7] includes the method for producing a carbon nanotube-containing film according to any one of the above [1] to [6], wherein in the fourth step, the dry film is cut without peeling the first sheet from the dry film.

[0024] According to this method, the first sheet is not peeled off from the dry-film, and thus the dry-film can be cut while being supported by the first sheet.

[0025] Therefore, the dry film can be cut stably.

[0026] Furthermore, since the obtained carbon nanotube-containing film can be supported by the first sheet, the handling of the carbon nanotube-containing film can be improved.

[0027] According to the method for producing a carbon nanotube-containing film of the present invention, it is possible to improve production efficiency.

[0028] Fig. 1 is a perspective view showing an example of a carbon nanotube-containing film. Fig. 2A to Fig. 2C show the steps of producing the carbon nanotube-containing film shown in Fig. 1, with Fig. 2A showing the second step of disposing a carbon nanotube dispersion between a first sheet and a second sheet, Fig. 2B showing the second step of rolling the carbon nanotube dispersion between the first sheet and the second sheet, and Fig. 2C showing the third step. Fig. 3 shows the fourth step following Fig. 2C.

[0029] 1. Carbon Nanotube-Containing Film As shown in FIG. 1 , the carbon nanotube-containing film 1 extends in the length direction. The length direction is perpendicular to the thickness direction. The cross section of the carbon nanotube-containing film 1 in the direction perpendicular to the length direction is substantially rectangular. The carbon nanotube-containing film 1 has, for example, a long thread shape. The shape of the carbon nanotube-containing film 1 is not limited. The carbon nanotube-containing film 1 may have a band shape that is flatter than a thread shape in the thickness direction.

[0030] The carbon nanotube-containing film 1 has a thickness T (dimension in the thickness direction) of, for example, 0.2 mm to 3 mm, or preferably 0.4 mm to 1 mm.

[0031] The width W (dimension in the width direction) of the carbon nanotube-containing film 1 is, for example, 0.3 mm to 5 mm, preferably 0.3 mm to 3 mm, more preferably 0.5 mm to 3 mm, and even more preferably 1 mm to 3 mm. The width direction is perpendicular to both the length direction and the thickness direction.

[0032] The aspect ratio (thickness T / width W) of the carbon nanotube-containing film 1 is, for example, 0.01 to 0.5. Specifically, the aspect ratio (thickness T / width W) of the cross section of the carbon nanotube-containing film 1 in a direction perpendicular to the longitudinal direction is, for example, 0.01 to 0.5.

[0033] There is no limitation on the length L (dimension in the longitudinal direction) of the carbon nanotube-containing film 1. The length L of the carbon nanotube-containing film 1 is, for example, 6 mm or more, preferably 10 mm or more, and more preferably 15 mm or more.

[0034] The carbon nanotube-containing film 1 contains carbon nanotubes as a conductive material, and optionally a binder and a dopant.

[0035] (1) Carbon Nanotubes Carbon nanotubes provide the carbon nanotube-containing film 1 with electrical conductivity.

[0036] The carbon nanotube may, for example, have a single-wall structure.

[0037] By containing carbon nanotubes in the carbon nanotube-containing film 1, the electrical properties of the carbon nanotubes as a P-type semiconductor can be utilized, and the carbon nanotube-containing film 1 can be produced efficiently.

[0038] The proportion of carbon nanotubes in the carbon nanotube-containing film 1 is, for example, 5 mass % or more, preferably 20 mass % or more, more preferably 60 mass % or more. When the proportion of carbon nanotubes is equal to or more than the above lower limit, the conductivity of the carbon nanotube-containing film 1 can be ensured.

[0039] The proportion of carbon nanotubes in the carbon nanotube-containing film 1 is, for example, 100 mass % or less.

[0040] The carbon nanotube-containing film 1 may contain a conductive material other than carbon nanotubes, but preferably contains only carbon nanotubes as the conductive material.

[0041] Examples of conductive materials other than carbon nanotubes include carbon materials, semiconductor materials, and conductive polymers.

[0042] Examples of carbon materials include carbon nanofibers, graphene, graphene nanoribbons, and fullerene nanowhiskers.

[0043] Examples of semiconductor materials include bismuth (Bi), tellurium (Te), antimony (Sb), cobalt (Co), zinc (Zn), silicon (Si), germanium (Ge), iridium (Ir), lead (Pb), and alloys thereof, skutterudite, and constantan. Semiconductor materials may contain metal elements, but due to their crystalline structure or the combination of elements in the alloy, they have a higher resistance than metals and behave as semiconductors. Semiconductor materials may also be semiconductor whiskers.

[0044] Examples of conductive polymers include polyacetylene, poly(p-phenylene vinylene), polypyrrole, polythiophene, polyaniline, poly(p-phenylene sulfide), a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS), a composite of poly(3,4-ethylenedioxythiophene) and polymethylsiloxane propylsulfonate (PEDOT:PSiPS), and a composite of poly(3,4-ethylenedioxythiophene) and paratoluenesulfonic acid (PEDOT:Tos).

[0045] (2) Binder The binder binds the carbon nanotubes together. Examples of the binder include insulating resins and conductive resins.

[0046] Examples of insulating resins include polyethylene glycol, epoxy resin, acrylic resin, urethane resin, polystyrene resin, and polyvinyl resin. Examples of polyvinyl resins include polyvinyl chloride, polyvinylpyrrolidone, polyvinyl alcohol, and polyvinyl acetate.

[0047] Examples of conductive resins include polyacetylene, poly(p-phenylene vinylene), polypyrrole, polythiophene, polyaniline, poly(p-phenylene sulfide), and poly(3,4-ethylenedioxythiophene).

[0048] As the binder, preferably, an insulating resin is used.

[0049] The proportion of the binder in the carbon nanotube-containing film 1 is, for example, 1 mass % or more, or preferably 30 mass % or more. When the proportion of the binder is equal to or more than the above lower limit, the tensile strength of the carbon nanotube-containing film 1 can be ensured.

[0050] The proportion of the binder in the carbon nanotube-containing film 1 is, for example, 90 mass % or less, preferably 50 mass % or less. When the proportion of the binder is equal to or less than the upper limit, the proportion of carbon nanotubes can be secured, and the conductivity of the carbon nanotube-containing film 1 can be secured.

[0051] The proportion of the binder in the carbon nanotube-containing film 1 is, for example, 1 part by mass or more, preferably 40 parts by mass or more, per 100 parts by mass of the carbon nanotubes. When the proportion of the binder is equal to or more than the above lower limit, the strength of the carbon nanotube-containing film 1 can be ensured.

[0052] The proportion of the binder in the carbon nanotube-containing film 1 is, for example, 900 parts by mass or less, preferably 100 parts by mass or less, relative to 100 parts by mass of the carbon nanotubes. When the proportion of the binder is equal to or less than the upper limit, the proportion of the carbon nanotubes can be secured, and the conductivity of the carbon nanotube-containing film 1 can be secured.

[0053] (3) Dopant When the carbon nanotube-containing film 1 has the electrical properties of an N-type semiconductor, the carbon nanotube-containing film 1 contains an N-type dopant.

[0054] The N-type dopant imparts electrical properties of an N-type semiconductor to the carbon nanotube-containing film 1. Examples of N-type dopants include polyoxyethylene alkyl ether (preferably polyoxyethylene stearyl ether, product name: Emulgen 350), benzocrown ether derivatives, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF ６), polyethyleneimine (PEI), ethylenediaminetetrakis(propoxylate-block-ethoxylate) tetrol (trade name: Tetronic® 1107), reduced benzyl viologen (reduced BV), diphenylphosphine (dpp), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb), bis(diphenylphosphinomethyl)phenylphosphine (dpmp), bis(diphenylphosphinoethyl)phenylphosphine (ppmdp), bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmpppm), triphenylphosphine (tpp), tris(p-fluorophenyl)phosphine (F-tpp), tris(p-chlorophenyl)phosphine (Cl-tpp), tris(p-methoxyphenyl)phosphine (P-methyl ... 1,3-dimethyl-2-(o-methoxyphenyl)benzimidazole (o-MeO-DMBI), hydrazine monohydrate (HH), phenylhydrazine (MPH), 1,2-diphenylhydrazine (DPH), diazabicycloundecene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). Preferred examples of the N-type dopant include triphenylphosphine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and polyoxyethylene stearyl ether.

[0055] 2. Method for Producing Carbon Nanotube-Containing Film Next, a method for producing the carbon nanotube-containing film 1 will be described.

[0056] The method for producing the carbon nanotube-containing film 1 includes a first step, a second step (see FIGS. 2A and 2B), a third step (see FIG. 2C), and a fourth step (see FIG. 3).

[0057] (1) First Step In the first step, a carbon nanotube dispersion liquid is prepared.

[0058] The carbon nanotube dispersion contains the above-mentioned carbon nanotubes, a dispersion medium, and, if necessary, the above-mentioned binder and dopant.

[0059] The proportion of carbon nanotubes in the carbon nanotube dispersion is 1 mass % or more, preferably 1.5 mass % or more, and for example, 10 mass % or less, preferably 5 mass % or less, more preferably 2.5 mass % or less.

[0060] When the proportion of carbon nanotubes in the carbon nanotube dispersion is equal to or greater than the lower limit, the viscosity of the carbon nanotube dispersion can be ensured, and in the second step, the carbon nanotube dispersion can be prevented from flowing excessively between the first sheet 11 and the second sheet 13. Therefore, in the second step, the carbon nanotube dispersion can be smoothly rolled.

[0061] When the proportion of carbon nanotubes in the carbon nanotube dispersion is equal to or less than the upper limit, the viscosity of the carbon nanotube dispersion can be prevented from becoming excessively high, and the flowability of the carbon nanotube dispersion can be ensured, which allows the carbon nanotube dispersion to be smoothly rolled in the second step.

[0062] The dispersion medium preferably has a boiling point of 100° C. or less at 1 atmosphere. Specific examples of the dispersion medium include water, alcohol, and aliphatic hydrocarbons.

[0063] Alcohols include, for example, methanol, ethanol, and isopropyl alcohol.

[0064] An example of the aliphatic hydrocarbon is n-hexane.

[0065] The boiling point of the dispersion medium at 1 atmosphere is, for example, 40°C or higher, or preferably 80°C or higher.

[0066] The proportion of the dispersion medium in the carbon nanotube dispersion is, for example, 60 mass % or more, or preferably 80 mass % or more.

[0067] When the carbon nanotube dispersion liquid contains a binder, the proportion of the binder in the carbon nanotube dispersion liquid is 0.1 mass % or more, for example, 20 mass % or less, or preferably 10 mass % or less.

[0068] To prepare a carbon nanotube dispersion, a mixer / stirrer or homogenizer is used to disperse the carbon nanotubes in a dispersion medium. For example, a stirring homogenizer is used to disperse the carbon nanotubes in a dispersion medium.

[0069] The viscosity of the obtained carbon nanotube dispersion at 25°C was －１ In this case, the viscosity is, for example, 350 mPa·s or more, preferably 800 mPa·s or more, and for example, 60,000 mPa·s or less, preferably 25,000 mPa·s or less.

[0070] If the viscosity of the carbon nanotube dispersion at 25°C is equal to or greater than the lower limit, the carbon nanotube dispersion can be prevented from flowing excessively between the first sheet 11 and the second sheet 13 in the second step. Therefore, the carbon nanotube dispersion can be smoothly rolled in the second step.

[0071] When the viscosity of the carbon nanotube dispersion at 25° C. is equal to or less than the upper limit, the flowability of the carbon nanotube dispersion can be ensured, and therefore the carbon nanotube dispersion can be smoothly rolled in the second step.

[0072] The viscosity of the carbon nanotube dispersion at 25° C. is measured by a cone-plate rotational viscometer specified in JIS Z 8803.

[0073] (2) Second Step Next, as shown in FIGS. 2A and 2B, in the second step, the carbon nanotube dispersion liquid 12 is rolled between the first sheet 11 and the second sheet 13.

[0074] The first sheet 11 supports the carbon nanotube dispersion liquid 12 .

[0075] A general film-like substrate can be used as the material of the first sheet 11. Examples of the material of the first sheet 11 include polyethylene terephthalate, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and 6,6-nylon.

[0076] The second sheet 13 covers the carbon nanotube dispersion liquid 12. The second sheet 13 is permeable to the dispersion medium. "Permeable to the dispersion medium" means that the second sheet 13 absorbs the liquid dispersion medium and allows the absorbed dispersion medium to evaporate. The second sheet 13 is breathable and water-absorbent.

[0077] Because the second sheet 13 is permeable to the dispersion medium, the second sheet 13 can absorb the dispersion medium in the carbon nanotube dispersion 12 while covering the carbon nanotube dispersion 12. Therefore, when the carbon nanotube dispersion 12 is rolled in the second step, excessive flow of the carbon nanotube dispersion 12 between the first sheet 11 and the second sheet 13 can be suppressed. Furthermore, the amount of dispersion medium in the carbon nanotube dispersion 12 can be reduced before drying the carbon nanotube dispersion 12 in the third step. Therefore, the carbon nanotube dispersion 12 can be dried with an increased concentration of carbon nanotubes in the carbon nanotube dispersion 12. As a result, the strength and conductivity of the carbon nanotube-containing film 1 can be improved. Furthermore, the drying time when drying the carbon nanotube dispersion 12 in the third step can be shortened.

[0078] The breathability of the second sheet 13 is measured by the Frazier method (Method A specified in JIS L 1096:2020).

[0079] The breathability of the second sheet 13 is, for example, 3 cm ３ / (cm ２ s) or more, preferably 25 cm ３ / (cm ２ s) or more, for example, 250 cm ３ / (cm２ ・s) or less.

[0080] The water absorbency of the second sheet 13 is evaluated by the water absorption time measured by the drop method (JIS L 1907:2010). The shorter the water absorption time, the higher the water absorbency.

[0081] The water absorption time of the second sheet 13 is, for example, 60 seconds or less, preferably 15 seconds or less, and for example, 0.1 seconds or more.

[0082] Examples of materials for the second sheet 13 include paper, nonwoven fabric, and cloth.

[0083] For example, a roll press or a plate press can be used to roll the carbon nanotube dispersion liquid 12. Preferably, in the second step, the carbon nanotube dispersion liquid 12 is rolled by a roll press.

[0084] By rolling the carbon nanotube dispersion 12 between the first sheet 11 and the second sheet 13, the flow of the carbon nanotube dispersion 12 can be suppressed by the second sheet 13 while the carbon nanotube dispersion 12 is spread over the first sheet 11. Therefore, the thickness of the coating of the carbon nanotube dispersion 12 can be controlled, and a thick carbon nanotube-containing film 1 can be formed.

[0085] The thickness T0 of the coating of the carbon nanotube dispersion liquid 12 is, for example, 2 mm or more, and for example, 50 mm or less, or preferably 20 mm or less.

[0086] After the second step is completed and before the third step, the second sheet 13 is peeled off from the carbon nanotube dispersion liquid 12 .

[0087] (3) Third Step Next, as shown in FIG. 2C, in the third step, the rolled carbon nanotube dispersion liquid 12 is dried to produce a dry film 14 containing carbon nanotubes.

[0088] The drying temperature in the third step is preferably less than 150°C, more preferably 130°C or lower, and for example, 25°C or higher, preferably 50°C or higher, more preferably 70°C or higher.

[0089] When the drying temperature in the third step is lower than 150° C., the dried film 14 can be obtained while maintaining the shape of the coating film of the carbon nanotube dispersion liquid 12 .

[0090] The drying time in the third step is, for example, 150 minutes or less, preferably 90 minutes or less, and for example, 10 minutes or more.

[0091] (4) Fourth Step Next, as shown in FIG. 3 , in the fourth step, the dry film 14 is cut along the cutting line C. In the fourth step, the dry film 14 is cut without peeling the first sheet 11 from the dry film 14. By not peeling the first sheet 11 from the dry film 14, the dry film 14 can be cut while being supported by the first sheet 11. Therefore, the dry film 14 can be cut stably. Furthermore, since the obtained carbon nanotube-containing film 1 can be supported by the first sheet 11, the handleability of the carbon nanotube-containing film 1 can be improved.

[0092] In the fourth step, even if the first sheet 11 is peeled off from the dry film 14, the carbon nanotube-containing film 1 can still be processed.

[0093] There is no limitation on the method for cutting the dry film 14. In the fourth step, the dry film 14 is preferably cut using a shear-cut slitting device. By using a shear-cut slitting device, the carbon nanotube-containing film 1 can be processed with high dimensional accuracy.

[0094] The dry film 14 is cut to obtain the carbon nanotube-containing film 1 shown in FIG.

[0095] 3. Effects and Benefits (1) According to the method for producing the carbon nanotube-containing film 1, as shown in FIGS. 2B to 3, a carbon nanotube dispersion 12 containing 1 mass % or more of carbon nanotubes is rolled (see FIG. 2B), dried (see FIG. 2C), and the resulting dried film 14 is cut (see FIG. 3).

[0096] Therefore, the dry film 14 containing carbon nanotubes can be produced by the simple process of rolling and drying the carbon nanotube dispersion 12 without going through the process of aggregating the carbon nanotube dispersion 12 in an aggregating liquid.

[0097] Then, the resulting dry film 14 is cut into a simple process, whereby the carbon nanotube-containing film 1 (see FIG. 1) having a desired shape can be obtained.

[0098] Therefore, the production efficiency of the carbon nanotube-containing film 1 can be improved.

[0099] Furthermore, as shown in Figure 2B, in the second step, by rolling the carbon nanotube dispersion liquid 12 between the first sheet 11 and the second sheet 13, the flow of the carbon nanotube dispersion liquid 12 can be suppressed by the second sheet 13 while the carbon nanotube dispersion liquid 12 can be spread over the first sheet 11.

[0100] Therefore, the thickness T0 of the coating of the carbon nanotube dispersion liquid 12 can be controlled, and the carbon nanotube-containing film 1 can be formed thick.

[0101] (2) According to the method for producing the carbon nanotube-containing film 1, the second sheet 13 is permeable to the dispersion medium.

[0102] Therefore, as shown in FIGS. 2A and 2B, in a state where the carbon nanotube dispersion liquid 12 is covered with the second sheet 13, the dispersion medium in the carbon nanotube dispersion liquid 12 can be absorbed by the second sheet 13.

[0103] Therefore, as shown in Figure 2B, when the carbon nanotube dispersion liquid 12 is rolled in the second step, excessive flow of the carbon nanotube dispersion liquid 12 between the first sheet 11 and the second sheet 13 can be prevented.

[0104] Furthermore, before the carbon nanotube dispersion liquid 12 is dried in the third step (see FIG. 2C), the amount of the dispersion medium in the carbon nanotube dispersion liquid 12 can be reduced.

[0105] Therefore, the carbon nanotube dispersion liquid 12 can be dried while the concentration of carbon nanotubes in the carbon nanotube dispersion liquid 12 is increased.

[0106] As a result, the strength and electrical conductivity of the carbon nanotube-containing film 1 can be improved.

[0107] Furthermore, when the carbon nanotube dispersion liquid 12 is dried in the third step, the drying time can be shortened.

[0108] (3) According to the method for producing the carbon nanotube-containing film 1, the drying temperature in the third step is preferably less than 150°C.

[0109] Therefore, when the drying temperature in the third step is lower than 150° C., the dried film 14 can be obtained while maintaining the shape of the coating film of the carbon nanotube dispersion liquid 12 .

[0110] (4) According to the method for producing the carbon nanotube-containing film 1, as shown in FIG. 3, in the fourth step, the dry film 14 is cut without peeling the first sheet 11 from the dry film 14.

[0111] Therefore, by not peeling the first sheet 11 from the dry-film 14 , the dry-film 14 can be cut while being supported by the first sheet 11 .

[0112] Therefore, the dry film 14 can be cut stably.

[0113] Furthermore, since the obtained carbon nanotube-containing film 1 can be supported by the first sheet 11, the handling of the carbon nanotube-containing film 1 can be improved.

[0114] 4. Modifications In the third step, the carbon nanotube dispersion liquid 12 may be dried without peeling the second sheet 13 from the carbon nanotube dispersion liquid 12 .

[0115] In the fourth step, the dry film 14 may be cut in a state where the first sheet 11 is peeled from the dry film 14 to obtain the carbon nanotube-containing film 1 .

[0116] Next, the present invention will be described based on examples and comparative examples. The present invention is not limited by the following examples. Furthermore, specific numerical values ​​of physical properties, parameters, etc. used in the following description can be replaced with the upper limit values ​​(numerical values ​​defined as "equal to or less than") or lower limit values ​​(numerical values ​​defined as "equal to or greater than") of the corresponding physical properties, parameters, etc. described in the above "Description of the Invention."

[0117] (1) Example 180 g of carbon nanotubes (product name: TUBALL 01RW02, manufactured by OCSiAl Corporation) and 11,790 g of isopropyl alcohol were mixed using a stirring homogenizer (product number: FM-56, manufactured by PRIMIX Corporation) to obtain a carbon nanotube dispersion (first step).

[0118] The proportion of carbon nanotubes in the carbon nanotube dispersion was 1.5 mass %.

[0119] Next, the carbon nanotube dispersion was placed on a polyethylene terephthalate film (first sheet, trade name: MRF-38, manufactured by Mitsubishi Chemical Corporation), and the carbon nanotube dispersion was placed on a paper separator (second sheet, air permeability: 110 cm ３ / (cm ２ s), water absorption time: 15 seconds, product name: NK base paper, manufactured by Nippon Paper Papylia Co., Ltd.

[0120] Next, the carbon nanotube dispersion liquid was rolled between the first sheet and the second sheet by a roll press (second step).

[0121] The thickness of the coating film of the carbon nanotube dispersion after rolling was 10 mm.

[0122] Next, the second sheet was peeled off, and the coating film of the carbon nanotube dispersion was dried at 120° C. for 90 minutes to prepare a dry film with a thickness of 0.4 mm (third step).

[0123] Next, the dried film 14 was cut using a shear-cut type slitting device to obtain a carbon nanotube-containing film having a width of 2 mm, a length of 20 cm and a thickness of 0.4 mm.

[0124] (2) Comparative Example 1 An attempt was made to produce a carbon nanotube-containing film in the same manner as in the example, except that a carbon nanotube dispersion liquid having a carbon nanotube concentration of 0.6 mass % was used, and the carbon nanotube dispersion liquid on the first sheet was not covered with a second sheet, but was instead spread with a doctor blade.

[0125] However, the thickness of the obtained film was 0.03 mm, and it was not possible to produce a carbon nanotube-containing film having the desired thickness (0.2 mm or more).

[0126] (3) Comparative Example 2 An attempt was made to produce a carbon nanotube-containing film in the same manner as in the example, except that a carbon nanotube dispersion liquid having a carbon nanotube concentration of 1.5 mass % was used, and the carbon nanotube dispersion liquid on the first sheet was not covered with a second sheet, and the carbon nanotube dispersion liquid on the first sheet was spread with a doctor blade.

[0127] Here, when spreading the carbon nanotube dispersion using a doctor blade, the carbon nanotube dispersion between the first sheet and the doctor blade is left on the first sheet (i.e., not scraped off), and the portion of the carbon nanotube dispersion on the first sheet that exceeds the desired thickness is scraped off and spread with the doctor blade.

[0128] In this regard, in this comparative example, the carbon nanotube dispersion liquid between the first sheet and the doctor blade was dragged by the doctor blade, and the carbon nanotube dispersion liquid could not be spread into a film.

[0129] Therefore, it was not possible to produce a carbon nanotube-containing film having a desired thickness (0.2 mm or more).

[0130] (4) Comparative Example 3 An attempt was made to produce a carbon nanotube-containing film in the same manner as in Example, except that a carbon nanotube dispersion liquid with a carbon nanotube concentration of 0.6% by mass was used.

[0131] However, the carbon nanotube dispersion flowed excessively between the first and second sheets, making it impossible to form the carbon nanotube dispersion into the desired thickness, and therefore, it was impossible to produce a carbon nanotube-containing film having the desired thickness (0.2 mm or more).

[0132] The above invention is provided as an exemplary embodiment of the present invention, but it is merely an example and should not be interpreted as being limiting. Modifications of the present invention that are obvious to those skilled in the art are included in the scope of the following claims.

[0133] The method for producing a carbon nanotube-containing film of the present invention can be used to produce a carbon nanotube-containing film.

[0134] REFERENCE SIGNS LIST 1 carbon nanotube-containing film 11 first sheet 12 carbon nanotube dispersion 13 second sheet 14 dried film

Claims

1. A method for producing a carbon nanotube-containing film, comprising: a first step of preparing a carbon nanotube dispersion containing 1% by mass or more of carbon nanotubes and a dispersion medium; a second step of rolling the carbon nanotube dispersion between a first sheet that supports the carbon nanotube dispersion and a second sheet that covers the carbon nanotube dispersion; a third step of drying the rolled carbon nanotube dispersion to produce a dry film containing carbon nanotubes; and a fourth step of cutting the dry film.

2. The method for producing a carbon nanotube-containing film according to claim 1, wherein at least one of the first sheet and the second sheet is permeable to the dispersion medium.

3. The method for producing a carbon nanotube-containing film according to claim 1, wherein the second sheet is peeled off from the carbon nanotube dispersion liquid after the second step and before the third step.

4. The method for producing a carbon nanotube-containing film according to claim 1, wherein the drying temperature in the third step is less than 150°C.

5. The method for producing a carbon nanotube-containing film according to claim 1, wherein the boiling point of the dispersion medium at 1 atmospheric pressure is 100°C or lower.

6. The method for producing a carbon nanotube-containing film according to claim 1, wherein in the fourth step, the dried film is cut with a slitting device.

7. The method for producing a carbon nanotube-containing film according to claim 1, wherein in the fourth step, the dry film is cut without peeling the first sheet from the dry film.

Images