JP2016126847A - Production method of transparent conductive film and transparent conductive laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a transparent conductive film achieving both conductivity and transparency, and a transparent conductive laminate produced by the production method.SOLUTION: The production method comprises: preparing a carbon nanotube (CNT) dispersion by adding CNT containing monolayer CNT having a diameter of 1.5 to 2.5 nm by 50 mass% or more, and a water-soluble dispersant having a molecular weight of 1000 or less to an aqueous solvent; applying the CNT dispersion on a transparent film substrate and drying to form a CNT thin film; cleaning the CNT thin film with a cleaning solution essentially comprising a solvent having an SP value of 10 to 20; and pressurizing the cleaned CNT thin film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a transparent conductive film and a transparent conductive film laminate used for a touch panel and the like. In detail, it is related with the manufacturing method of a transparent conductive film excellent in electroconductivity and transparency, and a transparent conductive film laminated body.

Transparent conductive films having a transparent conductive film are used for various displays such as touch panels and liquid crystal displays, electronic paper, and the like. High conductivity and transparency are required for the transparent conductive film used for the transparent conductive film.
Conventionally, an ITO (indium tin oxide) film has been used as the transparent conductive film. However, the ITO film has problems such as inevitable yellow coloration and increased resistance when bent.

On the other hand, a transparent conductive film using carbon nanotubes (hereinafter also referred to as CNT) is known as a transparent conductive film that can be expected to have high performance. Therefore, various methods for producing a transparent conductive film using CNT and a transparent conductive film using CNT have been proposed.
For example, in Patent Document 1, a dispersion containing CNT and a solvent is applied to the surface of a base material, and the CNT is made into a three-dimensional network structure by removing the solvent. A method for producing a CNT-containing coating film is described in which a dispersion containing the composition is applied and the dispersion is infiltrated into a three-dimensional network structure of CNTs.

  In Patent Document 2, as a CNT dispersion liquid for forming a transparent conductive film made of CNT, CNT, a dispersant, and a solvent are included, and the dispersant is a carboxyl group, an epoxy group, an amino group, and a sulfonyl group. A CNT dispersion which is an organic compound having a boiling point of 30 to 150 ° C. having one or more selected from is described.

In Patent Document 3, when observed with a transmission electron microscope, 50 or more of 100 CNTs are double-walled CNTs; 140 ± 10 cm ⁻¹ , 160 in Raman spectroscopic analysis at a wavelength of 532 nm A peak is observed at ± 10 cm ⁻¹ , 180 ± 10 cm ⁻¹ , 270 ± 10 cm ⁻¹ , 320 ± 10 cm ⁻¹ ; a peak is observed at 220 ± 10 cm ⁻¹ by Raman spectroscopy at a wavelength of 633 nm; In addition, a dispersion in which a CNT aggregate satisfying the fact that no peak is observed in a region of more than 190 cm ^{−1 and} less than 260 cm ^{−1 in} Raman spectroscopy at a wavelength of 532 nm is coated on a base material. A conductive film having a rate of 85% or more and a surface resistance value of less than 1 × 10 ⁵ Ω / □ is described.

  Further, Patent Document 4 discloses that in a transparent conductive film having a conductive layer having a single-walled CNT, the single-walled CNT exists in a bundled state with the conductive layer, and the single-walled CNT present in the bundled state has a length of 1. A transparent conductive film in which there are one having a length of 5 μm or less and a length exceeding 1.5 μm, and the number of bundles having a length exceeding 1.5 μm is larger than the number of bundles having a length of 1.5 μm or less Is described.

Japanese Patent No. 3665969 International Publication No. 2006/132254 JP 2009-149516 A Japanese Patent No. 5004338

As described above, the transparent conductive film is required to have high conductivity and high transparency.
Here, since CNT is black, in order to obtain high transparency, it is necessary to reduce the film thickness of the transparent conductive film using CNT. On the other hand, it is advantageous to increase the thickness of the transparent conductive film using CNT in order to obtain high conductivity.
That is, in a transparent conductive film using CNT, the relationship between conductivity and transparency is a trade-off relationship.

  However, in recent years, the electrical conductivity and transparency required for transparent conductive films have become higher. Therefore, there is a demand for a transparent conductive film using CNTs that more appropriately achieve both high conductivity and high transparency as compared to conventional transparent conductive films using CNTs.

  The object of the present invention is to solve such problems of the prior art, and to produce a transparent conductive film using CNTs, which has a high balance between high conductivity and high transparency in a good balance. It is in providing the manufacturing method which can be performed, and the transparent conductive laminated body which formed the transparent conductive film with this manufacturing method.

In order to achieve this object, the method for producing a transparent conductive film of the present invention comprises a carbon nanotube having a diameter of 1.5 to 2.5 nm of single-walled carbon nanotubes of 50% by mass or more and a molecular weight of 1000 or less. A preparation step of preparing a carbon nanotube dispersion liquid in which a carbon nanotube is dispersed by adding a water-soluble dispersant to an aqueous solvent,
A thin film forming process for forming a carbon nanotube thin film by applying a carbon nanotube dispersion liquid to a transparent film substrate and drying it,
A cleaning step of cleaning the carbon nanotube thin film with a cleaning liquid mainly composed of a solvent having an SP value of 10 to 20 to remove the water-soluble dispersant;
And the manufacturing method of the transparent conductive film characterized by having the pressurization process which pressurizes the carbon nanotube thin film which finished the washing | cleaning process.

In such a method for producing a transparent conductive film of the present invention, the pressing step is preferably performed by a roller pair or a pressing roller.
Moreover, it is preferable that the pressure in a pressurization process is 100-500 kg / cm.
Moreover, it is preferable to heat the member which pressurizes a carbon nanotube thin film at 60-100 degreeC in a pressurization process.
Further, it is preferable that the cleaning solution contains an acid having a pKa of 5 or less or an inorganic salt having a standard oxidation potential of 1 V or less.
Moreover, it is preferable that a washing process removes a water-soluble dispersant until the quantity of the water-soluble dispersant in a carbon nanotube thin film becomes 20 mass% or less with respect to a carbon nanotube.
Moreover, it is preferable to perform a pressurization process after irradiating the carbon nanotube thin film which finished the washing | cleaning process with either an ultraviolet-ray, visible light, or infrared light.
Moreover, it is preferable that a transparent film substrate has an adhesive layer on the surface.
The adhesive layer is preferably an alignment film.
Furthermore, it is preferable to have a process of rubbing the adhesive layer to form an alignment film before the thin film forming process.

The transparent conductive laminate of the present invention has an adhesive layer on a transparent film-like substrate, and the content of single-walled carbon nanotubes having a diameter of 1.5 to 2.5 nm is 50 on the adhesive layer. Having a transparent conductive film containing carbon nanotubes by mass or more, and
Carbon nanotubes, the ratio is 100 or more and the peak intensity of the peak intensity and 1350 ± 40 cm ^-1 of 1590 ± 50 cm ^-1 by Raman spectroscopy in the wavelength 532 nm; 900 ° C. from room temperature; the content of amorphous carbon 3 weight% or less In the thermogravimetric measurement up to 600 ° C. and the weight loss amount is 90 to 99% by mass; and the peak in the RBM region by Raman spectroscopy at a wavelength of 532 nm is 100 to 120 cm ⁻¹ and at least one on the main peak of 120～140Cm ^-1, and no peak within 250 cm ^-1 or more; four conditions that provide transparent electroconductive laminate and satisfies simultaneously.

In such a transparent conductive laminate of the present invention, the transparent conductive film preferably contains an acid having a pKa of 5 or less, or an inorganic salt having a standard oxidation potential of 1 V or less.
The adhesive layer is preferably an alignment film.
Furthermore, it is preferable that the transparent conductive film contains a water-soluble dispersant having a molecular weight of 1000 or less, and the content of the water-soluble dispersant is 20% by mass or less based on the carbon nanotubes.

  ADVANTAGE OF THE INVENTION According to this invention, the transparent conductive film and transparent conductive laminated body which were compatible with high electroconductivity and high transparency can be obtained using CNT (carbon nanotube).

It is a figure which shows notionally an example of the transparent conductive laminated body of this invention.

  Hereinafter, the manufacturing method of a transparent conductive film and the transparent conductive laminate of the present invention will be described in detail based on preferred examples shown in the accompanying drawings. In the present specification, A to B means A or more and B or less.

In FIG. 1, an example of the transparent conductive laminated body of this invention which formed the transparent conductive film with the manufacturing method of this invention is shown notionally.
A transparent conductive laminate 10 shown in FIG. 1 has an adhesive layer 14 on a substrate 12 and a transparent conductive film 16 on the adhesive layer 14.

The substrate 12 is a transparent film.
There is no restriction | limiting in particular in the board | substrate 12, Various transparent film materials (sheet-like material) utilized for the well-known transparent conductive laminated body which has a transparent conductive film can be utilized. In particular, any film or sheet-like material having a transmittance of 80% or more at a visible wavelength (380 to 780 nm) can be suitably used as the substrate 12 of the present invention. The transmittance can be measured by a method based on JISK7361-1 (ISO 13468-1).
As an example, as an example, polyester resin films such as polyethylene terephthalate (PET), polyethylene isophthalate, polyethylene naphthalate (PEN), polybutylene terephthalate, polyethylene-2,6-phthalenedicarboxylate, polyethylene (PE), polypropylene (PP), polyolefin resin film such as polystyrene, cycloolefin polymer film (COP), cyclic olefin resin film such as cycloolefin copolymer (COC), polyamide, polyvinyl chloride, polycarbonate, polyacrylonitrile, transparent polyimide, polyacrylate, Polymethacrylate, Polycarbonate (PC), Polyethersulfone, Polyetheretherketone (PEEK), Triacetylcellulose ( AC) resins, a film of polylactic acid.
Also, flexible glass sheets of 0.2 mm or less, for example, trade name G-Leaf (registered trademark) manufactured by Nippon Electric Glass Co., Ltd., trade name Spool manufactured by Asahi Glass Co., Ltd., product name Willow Glass manufactured by Corning International Co., Ltd. An ultra-thin glass sheet such as can also be used.
Above all, from the viewpoint of transparency in the visible light region, heat resistance, strength, ease of processing, raw material cost, etc., biaxially stretched PET film, PEN film, COP film, COC film, polyethersulfone film, TAC resin A film is preferably used.

  The thickness of the substrate 12 is not particularly limited, and the material for forming the substrate 12, the size, thickness, use of the transparent conductive laminate 10, rigidity, flexibility required for the transparent conductive laminate 10, etc. It may be set appropriately according to the above. Here, since the transparency of the substrate 12 is improved as the thickness is reduced, the thickness of the substrate 12 is generally preferably 200 μm or less.

A surface treatment or an adhesive layer 14 can be formed on the substrate 12 in order to ensure wettability and adhesion of the coating solution.
A known technique can be used for the surface treatment. As an example, surface activation treatments such as corona discharge treatment, ultraviolet-ozone treatment, glow discharge treatment, low-temperature atmospheric pressure plasma treatment, and laser treatment can be exemplified.

As long as the adhesive layer 14 can ensure the required light transmittance, the adhesive utilized for the well-known transparent conductive laminated body which has a transparent conductive film can utilize various.
As an example, polyurethane resin, acrylic resin, polyester resin, polyamide resin, polyethylene resin, polypropylene resin, polystyrene resin, polybutadiene resin, epoxy resin, polyvinyl acetate resin, polyvinyl alcohol resin, In addition, an adhesive containing such a copolymer as a main component can be given. These resins may contain 2 or more types. Moreover, you may add a crosslinking agent in order to adjust intensity | strength.
Among these, polyurethane resins, acrylic resins, and butadiene resins are preferably used. Specifically, a configuration in which a styrene-butadiene copolymer (hereinafter also referred to as “SBR”) or a water-based urethane resin contains a crosslinking agent is preferable. SBR is a copolymer mainly composed of styrene and butadiene, and further means a copolymer obtained by copolymerizing other components as required. It is known that this copolymer can be obtained with various physical properties by adjusting the content ratio of styrene and butadiene. SBR is preferably latex. Specifically, the product name Nipole manufactured by Nippon Zeon Co., Ltd., the product name NOGATEX manufactured by Sumitomo Nougatac Co., Ltd., the product name Crosslen manufactured by Takeda Pharmaceutical Company Limited, the product name Asahi Dow Latex manufactured by Asahi Dow Corporation, Commercial products sold by domestic and foreign manufacturers can be used. The content ratio of styrene / butadiene in SBR is preferably about 50/50 to 80/20. The ratio of SBR contained in the latex is preferably 30 to 50% by mass as the solid mass.
When two kinds of resins are used in combination, the polyurethane-based resin and the acrylic resin have good compatibility and become a material having high adhesion and durability. The content of the polyurethane resin is preferably 10% by mass to 99% by mass, more preferably 15% by mass to 98% by mass, and still more preferably 20% by mass to 95% by mass.
Examples of the crosslinking agent contained in the adhesive include triazine compounds (for example, dichloro-S-triazine derivatives), carbodiimide compounds (for example, N, N-dibutylbutylcarbodiimide), oxazoline compounds, epoxy compounds, and isocyanate compounds. From the viewpoint of film strength, a triazine compound, a carbodiimide compound, or an oxazoline compound is preferable. The content of the crosslinking agent is usually preferably 1 to 20% by mass with respect to the resin.

The thickness of the adhesive layer 14 is not particularly limited, and may be appropriately set according to the material for forming the adhesive layer 14, the required adhesive strength, the size, thickness, application, etc. of the transparent conductive laminate 10. That's fine.
Specifically, the thickness of the adhesive layer 14 is preferably 0.005 to 10 μm, more preferably 0.01 to 5 μm, and still more preferably 0.05 to 1 μm.
By making the thickness of the adhesive layer 14 in the above range, the necessary adhesive force can be suitably secured, and by making the adhesive layer 14 thinner, the flatness and transparency of the transparent conductive laminate 10 are improved. This is preferable.

The adhesive layer 14 may be formed by a known method depending on the material for forming the adhesive layer 14.
For example, roll coating, bar coating, dip coating, spin coating, casting, die coating, blade coating, bar coating, gravure coating, curtain coating, spray coating, doctor coating, etc. are used. be able to.

Here, the adhesive layer 14 is preferably an alignment film.
By using the adhesive layer 14 as an alignment film, the CNTs (carbon nanotubes) constituting the transparent conductive film 16 can be loosened, and the longitudinal direction can be aligned along the grooves. Can be improved.

Such an alignment film is formed by polymer rubbing treatment, formation of a layer having a microgroove, or accumulation of an organic compound (for example, ω-tricosanoic acid, methyl stearylate) by a Langmuir-Blodgett method (LB film). It can be provided by means. Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known. In the present invention, an alignment film formed by rubbing treatment or light irradiation is preferable. In particular, an alignment film formed by a rubbing treatment of a polymer is preferable. The rubbing treatment can be generally carried out by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. In particular, in the present invention, it is described in “Liquid Crystal Handbook” (Maruzen Co., Ltd., 2000). It is preferable to carry out by the method described above.
The polymer used for the alignment film is described in many documents, and many commercially available products can be obtained. For the alignment film used in the present invention, polyvinyl alcohol and its derivatives, polyamide, polyimide and the like are preferably used. In particular, modified polyvinyl alcohol to which a hydrophobic group is bonded is preferable. As the alignment film, an alignment film used for a discotic liquid crystal can be used as the alignment film for the liquid crystal. As such an alignment film, reference can be made to the description on page 43, line 24 to page 49, line 8 of the pamphlet of WO01 / 88574A1. Such a resin can be prepared by coating on the above-mentioned transparent substrate and curing with a crosslinking agent as appropriate. As the crosslinking agent, aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, and isoxazole compounds can be used in addition to the above-mentioned crosslinking agents. .

In the transparent conductive laminate 10, a transparent conductive film 16 is formed on the adhesive layer 14.
The transparent conductive film 16 contains a single-walled CNT having a diameter of 1.5 to 2.5 nm having a content of 50% by mass or more and a water-soluble dispersant having a molecular weight of 1000 or less.

A CNT is a single-walled CNT in which a single carbon film (graphene sheet) is wound in a cylindrical shape, a double-walled CNT in which two graphene sheets are wound in a concentric shape, and a plurality of graphene sheets in a concentric circle There are multi-walled CNTs wound in a shape. In the present invention, if the content of single-walled CNT having a diameter of 1.5 to 2.5 nm is 50% by mass or more, two or more kinds of single-walled CNT, double-walled CNT, and multilayered CNT may be used in combination. Good.
Single-walled CNTs may be metallic or semiconducting, or a mixture of both. Metallic CNT is preferable. Usually, when synthesizing single-walled CNT, it becomes a mixture of semiconducting CNT and metallic CNT, so the synthesized product may be used as it is, but the semiconducting CNT and metallic CNT are separated and depending on the application The content ratio may be adjusted as appropriate. In addition, the CNT may contain a metal, an organic compound, or the like, or may contain a molecule such as fullerene.

Moreover, as CNT, the CNT which modified or processed CNT can also be utilized. Modification or treatment methods include ferrocene derivatives and nitrogen-substituted fullerenes (azafullerenes), hole doping with acids and electron-accepting compounds, doping CNTs by electron doping with electron-donating compounds, in vacuum A method of heating the CNTs is exemplified.
The transparent conductive film 16 may contain nanocarbons such as carbon nanohorns, carbon nanocoils, nanographene, and graphene oxide in addition to single-walled CNTs and multilayered CNTs.

  There is no restriction | limiting in particular in the average length of CNT used by this invention, According to the use etc. of a transparent conductive laminated body, it can select suitably. Specifically, although it depends on the distance between the electrodes, the average length of the CNT is preferably 0.01 to 2000 μm, more preferably 0.1 to 1000 μm from the viewpoints of manufacturability, film formability, conductivity, and the like. 0.5 to 500 μm is particularly preferable.

The CNT contained in the transparent conductive film 16 has a content of single-walled CNTs having a diameter of 1.5 to 2.5 nm of 50% by mass or more. The content of single-walled CNT having a diameter of 1.5 to 2.5 nm in the CNT is preferably 70% by mass or more, and more preferably 80% by mass or more.
When the content of the single-walled CNT having a diameter of 1.5 to 2.5 nm is less than 50% by mass, the content of the multi-walled CNT having low conductivity or amorphous carbon increases, and sufficient conductivity cannot be obtained. Moreover, a problem also arises in that the transparency of the transparent conductive laminate 10 is lowered.

Moreover, in the transparent conductive laminated body 10 of this invention, CNT which comprises the transparent conductive film 16 satisfies the following characteristics.
That is, the CNT constituting the transparent conductive film 16 has a peak intensity of G band caused by in-plane stretching vibration of the graphene structure of CNT observed at 1590 ± 50 cm ⁻¹ by Raman spectroscopy with a wavelength of 532 nm, and 1350 ± 40 cm. The ratio (G / D ratio) to the peak intensity of the D band derived from the defect of CNT observed at ⁻¹ is 100 or more, and the stretching of the CNT in the diameter direction is confirmed by Raman spectroscopy with a wavelength of 532 nm. In the peak of the resulting RBM (Radical Breathing Mode) region, there is no peak at 250 cm ⁻¹ or more, and there is a main peak in at least one of 100 to 120 and 120 to 140.
In addition, the CNT constituting the transparent conductive film 16 has an observed weight loss starting temperature of 600 ° C. or higher and a weight loss amount of 9 to 99 mass in thermogravimetry (TGA) from room temperature to 900 ° C. %, And the amorphous carbon content is 3% by mass or less.

  It can be presumed that the higher the G / D ratio is, the smaller the number of defects. The G / D ratio of the CNT is 100 or more, preferably 150 or more, more preferably 200 or more. By transparently dispersing such single-walled CNTs in the transparent conductive film 16, the transparent conductive having excellent conductivity A membrane 16 is obtained.

Many CNTs contain amorphous carbon as an impurity. In the transparent conductive laminate 10 of the present invention, the CNT of the transparent conductive film 16 has an amorphous carbon content of 3% by mass or less, preferably 1% by mass or less.
By setting the content of amorphous carbon, which is an impurity, to 3% by mass or less, the dispersibility of CNT is improved, and the transparency can be improved without lowering the conductivity.

On the other hand, in thermogravimetry, amorphous carbon begins to lose weight at about 4 to 500 ° C., and CNT starts to lose weight at 600 ° C. or higher.
Therefore, in thermogravimetry from room temperature to 900 ° C., the CNT has a reduced weight starting temperature of 600 ° C. or more and a weight reduction amount of 90 to 99% by mass, so that the amount of impurities is reduced as before By the CNT, the transparent conductive film 16 having excellent conductivity and the like can be obtained.

In the transparent conductive laminate 10 of the present invention, the transparent conductive film 16 has a CNT content of 50% by mass or more of single-walled CNTs having a diameter of 1.5 to 2.5 nm.
Therefore, CNT is at the peak of RBM region by Raman spectroscopy in the wavelength 532 nm, have a main peak in 100～120Cm ^-1 and / or 120～140Cm ^-1, and no peak at 250 cm ^-1 or more.

  That is, according to the present invention, it is possible to obtain a transparent conductive film 16 having sufficient conductivity even when thin using CNT having high conductivity. Accordingly, the present invention realizes the transparent conductive film 16 which preferably satisfies both the conductivity and transparency of the transparent conductive film which are normally in a trade-off relationship.

Such CNTs can be produced by an improved direct injection pyrolysis synthesis method (e-DIPS method (Enhanced Direct Injection Pyrolytic Synthesis) method) developed by the National Institute of Advanced Industrial Science and Technology. That is, in the production method of the present invention, CNTs produced by an improved direct injection pyrolysis synthesis method can be suitably used.
The improved direct injection pyrolysis synthesis method (e-DIPS method) is positioned as a kind of floating flow reaction method (vapor phase flow reaction) of chemical vapor deposition method (CVD method), and an iron / cobalt catalyst (or its precursor). Body) and / or a molybdenum-based catalyst (or a precursor thereof) is sprayed into a high-temperature reactor by spraying or the like to generate catalyst nanoparticles and float them in the gas phase. In addition to aromatic carbon such as toluene or aliphatic carbon such as decalin or decane, ethylene and acetylene as the second carbon source coexist with sulfur compounds such as thiophene as the reaction accelerator, and carrier gas This is a method of synthesizing single-walled CNTs in a gas phase fluid phase by introducing them into the high-temperature reactor under a hydrogen gas flow.

50 mass% or more is preferable and, as for content of CNT in the transparent conductive film 16, 80 mass% or more is more preferable.
By making content of CNT in the transparent conductive film 16 into 50 mass% or more, it is preferable at the point from which the transparent conductive film 16 which was compatible with electroconductivity and transparency is obtained.

In addition to such CNTs, the transparent conductive film 16 contains a water-soluble dispersant having a molecular weight of 1000 or less.
The water-soluble dispersant will be described in detail later.

There is no restriction | limiting in particular in the thickness of the transparent conductive film 16, According to the magnitude | size and thickness of the transparent conductive laminated body 10, the use of the transparent conductive laminated body 10, required transparency, electroconductivity, etc. suitably , You can set.
Specifically, the thickness of the transparent conductive film 16 is preferably 0.003 to 0.5 μm, and more preferably 0.01 to 0.3 μm.
By setting the thickness of the transparent conductive film 16 to 0.003 μm or more, it is preferable in that good conductivity can be obtained.
In addition, it is preferable that the thickness of the transparent conductive film 16 is 0.5 μm or less in that good transparency can be obtained and the thickness of the transparent conductive laminate 10 can be reduced.
That is, by setting the thickness of the transparent conductive film 16 to 0.003 to 0.5 μm, it is possible to more appropriately obtain high conductivity and high transparency in a balanced manner.

Hereinafter, a method for manufacturing the transparent conductive film 16 will be described.
First, a CNT dispersion liquid is prepared by adding a CNT having a diameter of 1.5 to 2.5 nm and having a single-wall CNT content of 50% by mass or more and a water-soluble dispersant having a molecular weight of 1000 or less to an aqueous solvent. .
As described above, the CNT has a ratio of the peak intensity of 1590 ± 50 cm ^{−1 and} the peak intensity of 1350 ± 40 cm ⁻¹ produced by the improved direct-injection pyrolysis synthesis method at a wavelength of 532 nm of 100 or more. A content of amorphous carbon of 3% by mass or less; in thermogravimetry from room temperature to 900 ° C., a weight reduction starting temperature is 600 ° C. or more and a weight reduction amount is 90 to 99% by mass; and a wavelength of 532 nm in the peak of the RBM region by Raman spectroscopy, it has a main peak in at least one of 100～120Cm ^-1 and 12～140Cm ^-1, and no peak at 250 cm ^-1 or more; four conditions of, It is preferable to use a material that satisfies all requirements.

Specifically, the aqueous solvent is a water-soluble solvent.
Examples of the aqueous solvent include water, methanol, ethanol, propanol, isopropanol, ethylene glycol, propylene glycol, acetone, 2-butanone, 1-methoxy-2-propanol, dimethyl sulfoxide, butanol, sec-butanol, isobutyl alcohol, tert-butanol, glycerin, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, tetrahydrofuran, 1,4-dioxane, 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, N-ethyl Examples include pyrrolidone, methyl carbitol, butyl carbitol and the like.
The aqueous solvent may be a mixed solvent of two or more.

The CNT dispersion contains a water-soluble dispersant having a molecular weight of 1000 or less in order to disperse CNT suitably in an aqueous solvent.
In the production method of the present invention, the use of a water-soluble dispersant having a molecular weight of 1000 or less facilitates the removal of the water-soluble dispersant in the washing step described later.

As the water-soluble dispersant, a known water-soluble dispersant can be used as long as it has a molecular weight of 1000 or less and has a function of dispersing CNTs. More specifically, as long as the water-soluble dispersant is dissolved in water, a polar solvent, a mixture of water and a polar solvent, and has adsorbability to CNTs, various water-soluble dispersants can be used. .
Examples thereof include ionic water-soluble dispersants (anionic water-soluble dispersants, cationic water-soluble dispersants, amphoteric water-soluble dispersants), nonionic water-soluble dispersants (nonionic water-soluble dispersants), and the like. From the viewpoint of good dispersibility of CNTs and easy removal by washing, an ionic water-soluble dispersant is preferable, and an anionic water-soluble dispersant is more preferable.

Examples of the anionic water-soluble dispersant include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, aromatic sulfonic acid-based water-soluble dispersants, dialkyl sulfosuccinates, and linear alkylbenzene sulfonates. Branched alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamides Disodium salts, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, sulfate esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfates Ester salt, fatty acid monoglyceride sulfate ester, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkylphenyl ether phosphate Ester salts, saponification products of styrene-maleic anhydride copolymer, saponification products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensates, aromatic sulfonates, aromatic substituted poly Oxyethylene sulfonates, monosoap anionic water-soluble dispersants, ether sulfate water-soluble dispersants, phosphate water-soluble dispersants and carboxylic acid water-soluble dispersants, fatty acid salts, etc. It is below.
More specifically, octylbenzenesulfonate, nonylbenzenesulfonate, dodecylbenzenesulfonate, dodecyldiphenyl ether disulfonate, monoisopropylnaphthalenesulfonate, diisopropylnaphthalenesulfonate, triisopropylnaphthalenesulfonate, Examples include dibutyl naphthalene sulfonate, naphthalene sulfonic acid formalin condensate salt, sodium cholate, potassium cholate, sodium deoxycholate, potassium deoxycholate, sodium glycocholate, sodium lithocholic acid, cetyltrimethylammonium bromide and the like.

Examples of the cationic water-soluble dispersant include alkylamine salts and quaternary ammonium salts.
Examples of amphoteric water-soluble dispersants include alkylbetaine-based water-soluble dispersants and amine oxide-based water-soluble dispersants.

  Nonionic water-soluble dispersants include, for example, sugar ester water-soluble dispersants such as sorbitan fatty acid esters and polyoxyethylene sorbitan fatty acid esters, polyoxyethylene resin acid esters, and fatty acid ester water-soluble waters such as polyoxyethylene fatty acid diethyl. Dispersant, fatty acid ester of glycerol of polyhydric alcohol type, fatty acid ester of pentaerythritol, fatty acid ester of sorbitol and sorbitan, fatty acid ester of sucrose, alkyl ether of polyhydric alcohol, fatty acid amide of alkanolamines, polyoxyethylene Ether-based water-soluble dispersants such as alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene / polypropylene glycol, polyoxyalkylene octylphenyl ether, Aromatic nonionic such as reoxyalkylene nonyl phenyl ether, polyoxyalkyl dibutyl phenyl ether, polyoxyalkyl styryl phenyl ether, polyoxyalkyl benzyl phenyl ether, polyoxyalkyl bisphenyl ether, polyoxyalkyl cumyl phenyl ether A water-soluble dispersing agent is mentioned.

Below, the specific example of the water-soluble dispersing agent which can be used is illustrated.

Among such water-soluble dispersants, ionic water-soluble dispersants are preferable, and anionic water-soluble dispersants are more preferable. Among these, cholate and deoxycholate are more preferably used.
By using ionic water-soluble dispersants, particularly cholate and deoxycholate as water-soluble dispersants, CNTs can be well dispersed in the CNT dispersion. As a result, it is possible to form a transparent conductive film 16 containing a large amount of CNTs that is long and has few defects, and higher conductivity is obtained.

  The CNT dispersion may be prepared by a known method using, for example, a homogenizer, a high-speed rotating thin film disperser, an ultrasonic homogenizer, a bead mill, a ball mill, a roll mill, a jet mill, or an ultrahigh pressure processing machine.

In the CNT dispersion, the content of CNT is preferably 0.01 to 2% by mass, and more preferably 0.1 to 1% by mass.
By setting the CNT content in the CNT dispersion to 0.01% by mass or more, a dense network of CNT chains serving as a conductive path is formed, which is preferable in terms of improving conductivity.
Moreover, by making the content of CNT in the CNT dispersion liquid 2% by mass or less, it is preferable in that the dispersibility of CNT is improved and the transparency of the transparent conductive film 16 is improved.

In the CNT dispersion, the content of the water-soluble dispersant is preferably 0.05 to 3% by mass, and more preferably 0.1 to 1% by mass.
By setting the content of the water-soluble dispersant in the CNT dispersion to 0.05% by mass or more, it is preferable in that CNT can be suitably dispersed and a uniform transparent conductive film 16 can be formed.
In addition, by setting the content of the water-soluble dispersant in the CNT dispersion to 3% by mass or less, the amount of the water-soluble dispersant can be easily reduced to 20% by mass or less of the CNT in the cleaning step described later, and the conductivity is improved. It is preferable in that it can be expressed at a high level.

  In addition to the aqueous solvent, CNT, and the water-soluble dispersant, the CNT dispersion liquid may be a dispersion aid, a CNT p-type or n-type doping agent, a viscosity modifier for the dispersion liquid, and a coating surface. You may contain surfactant etc. as an upper improvement agent. Moreover, you may contain the acid whose pKa value mentioned later is 5 or less as a doping agent, or inorganic salt whose standard oxidation potential is 1 V or less.

After the CNT dispersion is prepared, the CNT coating liquid is applied to the surface of the substrate 12 and dried to form a CNT thin film.
Preferably, as shown in FIG. 1, a CNT thin film is formed by applying a CNT coating liquid to the adhesive layer 14 formed on the substrate 12 and drying it. More preferably, a rubbing process using a rubbing cloth or a rubbing roller is performed on the adhesive layer 14, and after the adhesive layer 14 is used as an alignment film, a CNT coating solution is applied and dried to form a CNT thin film.

In the method for producing a transparent conductive film of the present invention, the method for applying the CNT dispersion liquid is not particularly limited, and general liquid phase film forming methods such as conventionally known coating methods and printing methods can be widely used.
The CNT dispersion can be applied by die coating, dip coating, air knife coating, blade coating, doctor coating, curtain coating, bar coating, roller coating, spray coating, spin coating, wire bar Any known coating method such as a coating method, a gravure coating method, and a slide coating method can be used.
In addition, as a printing method, for example, a printing method such as a letterpress (letter) printing method, a stencil (screen) printing method, a lithographic (offset) printing method, an intaglio (gravure) printing method, a spray printing method, or an ink jet printing method is used. A coating film can be formed.
In addition, what is necessary is just to set suitably the coating film thickness which can obtain the transparent conductive film 16 of the target film thickness according to the density | concentration of CNT in a CNT dispersion liquid, etc. as the coating film thickness of a CNT dispersion liquid.
For drying the CNT dispersion liquid, all known drying methods such as heating with a heater, a method using a hot plate, and hot air drying can be used.

After the CNT dispersion liquid is applied and dried to form a CNT thin film, the CNT thin film is then washed with a cleaning liquid mainly composed of a solvent having an SP value of 10 to 20. By this cleaning, the water-soluble dispersant is removed from the CNT thin film.
In the cleaning liquid, “mainly a solvent having an SP value of 10 to 20” indicates that the content of the solvent having an SP value of 10 to 20 in the cleaning liquid is 50% by mass or more.

The water-soluble dispersant is usually an insulator, and when the transparent conductive film 16 contains a water-soluble dispersant, the conductivity of the transparent conductive film 16 becomes low.
On the other hand, in this invention, the transparent conductive film 16 which has favorable electroconductivity can be formed by performing a washing | cleaning process and removing a water-soluble dispersing agent from a CNT thin film.

  In the present invention, the use of a cleaning liquid mainly composed of a solvent having an SP value of 10 to 20 in the cleaning process improves the compatibility with the water-soluble dispersant and increases the interaction, thereby increasing the water-soluble dispersion. It becomes possible to remove the agent well.

Specific examples of the solvent having an SP value of 10 to 20 include 1 to 3 alcohols such as methanol, ethanol, n-propanol, isopropanol, allyl alcohol, 1,3-propanediol, methyl glycol, n- Butanol, 2-butanol, t-butanol, 1,4-butanediol, 1,3-butanediol, n-pentanol, amyl alcohol, neopentyl glycol, furfuryl alcohol, n-hexanol, 2-ethylbutanol, 2 -Methylpentane-1,3-diol, 2,2-dimethylbutanediol, diacetone alcohol, n-heptyl alcohol, n-octyl alcohol, phenol, benzyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethyl Lene glycol monophenyl ether, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, dipropylene glycol, diethylene glycol monomethyl ether, glycerin, etc., ketones such as acetone, methyl ethyl ketone, cyclohexanone, amides such as methylformamide, dimethylformamide In addition, 1,4-dioxane, morpholine, acetonitrile, dimethyl sulfoxide, sulfolane, tetramethylurea and the like are exemplified.
Among them, methanol, ethanol, n-propanol, isopropanol, allyl alcohol, n-butanol, 2-butanol, t-butanol, acetone, methyl ethyl ketone, 1,4-dioxane, acetonitrile and the like having a low molecular weight and a relatively low boiling point Particularly, those having a boiling point of 120 ° C. or less are preferably used in terms of good drying properties of the coating film.
A plurality of solvents having an SP value of 10 to 20 may be used in combination. The cleaning liquid may contain water at less than 50% by mass.

Here, the cleaning solution preferably contains an acid having a pKa value of 5 or less, which is an index of acidity, or an inorganic salt having a standard oxidation potential of 1 V or less.
When the cleaning liquid contains such an acid or inorganic salt, these components can be contained in the CNT thin film in the cleaning step. That is, in the transparent conductive laminate 10 of the present invention, the transparent conductive film 16 preferably contains an acid having a pKa value of 5 or less or an inorganic salt having a standard oxidation potential of 1 V or less.
An acid having a pKa value of 5 or less or an inorganic salt having a standard oxidation potential of 1 V or less acts as a p-type dopant for CNT. Therefore, when the cleaning liquid contains such an acid or inorganic salt, the transparent conductive film 16 having better conductivity can be obtained by adding a dopant to the CNT.

Various known acids can be used as the acid having a pKa value of 5 or less. Specifically, hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, periodic acid, acetic acid, chloroacetic acid, fluoroacetic acid, trichloroacetic acid, trifluoroacetic acid, benzenesulfonic acid, toluenesulfonic acid, benzoic acid, p-chlorobenzoic acid , P-nitrobenzoic acid, p-hydroxybenzoic acid, salicylic acid and the like.
Various known inorganic salts having a standard oxidation potential of 1 V or less can be used. Specifically, ferrous salts such as ferrous chloride, ferrous hydroxide and ferrous acetate, ferric salts such as ferric chloride, ferric hydroxide and ferric acetate, chloride Examples thereof include copper salts such as cuprous, cuprous acetate, cupric chloride and cupric acetate, and zinc salts such as zinc chloride and zinc acetate.

The content of an acid having a pKa value of 5 or less in the cleaning solution or an inorganic salt having a standard oxidation potential of 1 V or less is a solvent having an SP value of 10 to 20, an acid having a pKa of 5 or less, or a standard oxidation potential of 1 V or less. What is necessary is just to set suitably according to the kind etc. of inorganic salt.
Specifically, the content of such an acid or inorganic salt in the cleaning liquid is preferably 0.1 to 5% by mass, and more preferably 0.5 to 3% by mass.
By setting the content of acid or the like in the cleaning liquid to 0.1% by mass or more, it is preferable in that CNT can be sufficiently doped.
Moreover, it is preferable at the point which can remove a water-soluble dispersing agent efficiently by content of acids etc. in a washing | cleaning liquid being 5 mass% or less.

  In addition to the solvent having an SP value of 10 to 20, an acid having a pKa value of 5 or less, or an inorganic salt having a standard oxidation potential of 1 V or less, the cleaning liquid may be cationic, anionic, or nonionic as required. A surfactant may be contained.

For the cleaning of the CNT thin film using such a cleaning liquid, various methods for exposing the CNT thin film to the cleaning liquid can be used.
As an example, a method of immersing a substrate 12 (substrate 12 and adhesive layer 14) on which a CNT thin film is formed in a cleaning liquid is exemplified. Further, during the immersion, the cleaning liquid may be stirred or circulated, ultrasonic vibration may be applied, and the cleaning liquid may be heated or cooled.
As another method, the CNT thin film may be cleaned by rinsing the CNT thin film with a cleaning solution.

Here, the cleaning process for removing the water-soluble dispersant from the CNT thin film is performed by the dipping treatment or the rinse treatment so that the amount of the water-soluble dispersant contained in the CNT thin film is 20% by mass or less with respect to the CNT. The cleaning liquid temperature is preferably adjusted.
That is, in the transparent conductive laminate 10 of the present invention, the water-soluble dispersant contained in the transparent conductive film 16 is preferably 20% by mass, more preferably 10% by mass or less, based on CNT. More preferably, it is 5 mass% or less.

As described above, the water-soluble dispersant is usually an insulator, and the greater the amount of the water-soluble dispersant, the lower the conductivity.
By performing the washing step until the amount of the water-soluble dispersant contained in the CNT thin film is 20% by mass or less based on CNT, it is preferable in that a transparent conductive film having good conductivity can be obtained.

  In addition, content of the water-soluble dispersing agent with respect to CNT in a CNT thin film can be measured using well-known methods, such as a thermogravimetric / differential thermal analysis method (TG / DTA) and a microscopic infrared spectroscopy, for example. .

When the cleaning of the CNT thin film is completed, after the CNT thin film is dried, a pressurizing step of pressurizing and compressing the CNT thin film is performed to produce the transparent conductive film 16 to obtain the transparent conductive laminate 10.
In the manufacturing method of the present invention, the CNT thin film from which the water-soluble dispersant has been removed by washing is pressurized and compressed to increase the number of contact points between the CNTs and to obtain a transparent conductive film 16 having higher conductivity. Can do. Moreover, since the film thickness of the transparent conductive film 16 can be made thin and uniformly smoothed by performing the pressurizing step, the transparency can be improved.

For the pressurization, various known methods for pressurizing and compressing the sheet-like material can be used.
Specifically, so-called calendar processing is effective, and the following calendar processing roll and calendar processing conditions may be used.
As the calendering roll, heat-resistant plastic elastic rolls such as epoxy, polyester, nylon, polyimide, polyamide, polyimide amide (which may be kneaded with carbon, metal or other inorganic compounds) and metal rolls Use a combination. Moreover, it is preferable to process between metal rolls because a flatter transparent conductive layer surface can be obtained. A metal roll is disposed on the side in contact with the surface of the transparent conductive layer in order to obtain a flatter surface. A plastic elastic roll is usually arranged on the side in contact with the support surface, but a metal roll is preferably arranged.

As the calendering conditions, conditions applicable to the magnetic recording material described in JP-A-2009-96798 can be used.
Specifically, the temperature of the calendar roll, that is, the calendar temperature is in the range of 60 to 100 ° C, preferably in the range of 70 to 100 ° C, and particularly preferably in the range of 80 to 100 ° C.
The pressure of the calendering process is appropriately set according to the thickness of the CNT thin film, the CNT content in the CNT thin film, the thickness of the target transparent conductive film 16, and the like, but preferably 100 to 500 kg / cm ² . The range is more preferably 200 to 450 kg / cm ² , and the condition of 300 to 400 kg / cm ² is particularly preferable.
The processing speed of the calendar process is preferably in the range of 10 to 900 m / min.
By setting the pressure of the calendar process in the pressurizing step to 100 kg / cm ² or more, it is preferable in that the CNT thin film is suitably compressed by pressurization, and a transparent conductive film 16 having more excellent conductivity and transparency can be obtained. Moreover, it is preferable at the point which can prevent the cutting | disconnection and damage of CNT suitably by making the pressure in a pressurization process into 500 kg / cm < ² > or less.
By heating the temperature of the calender roll to 60 ° C. or higher in the pressurizing step, CNT chain contacts are effectively formed, which is preferable in terms of improving conductivity. Moreover, if the temperature of the calender roll is too high, there may be inconveniences such as defects in the contact points of the CNT chain, and a decrease in the transportability of the transparent conductive film. Such problems can also be avoided.
As an index of the calendar process, the center plane of the surface of the transparent conductive layer measured in an area of 250 μm × 250 μm is measured under the condition of a cutoff value of 0.25 mm using an optical interference type surface roughness meter HD-2000 manufactured by WYKO. A change amount (reduction amount) ΔRa of the average surface roughness Ra can be used.

Here, in the manufacturing method of the present invention, before performing such a pressurizing step, the CNT thin film that has finished the cleaning step is irradiated with any one of ultraviolet rays, visible light, and infrared rays, and then the pressurizing step is performed. Is preferred.
The reason is unknown, but by applying a pressing process after irradiating the CNT thin film with either ultraviolet light, visible light, or infrared light, the thinning and homogenization of the pressing process proceeded more effectively, and the conductive process It is preferable in that the property is further improved.
The irradiation amount of any one of ultraviolet rays, visible light and infrared rays depends on the energy of the light source, but is preferably 100 mJ / cm ^{2 to 5} J / cm ² , more preferably 200 mJ / cm ^{2 to 2} J / cm ² , particularly 300 mJ / range cm ² ~1J / cm ² is preferred. When the irradiation amount is less than 100 mJ / cm ² , the above effect is not observed, and when the irradiation amount is more than 5 J / cm ² , the transparent conductive film is colored.

  As mentioned above, although the manufacturing method of the transparent conductive film and transparent conductive laminated body of this invention were demonstrated in detail, this invention is not limited to the above-mentioned example, In the range which does not deviate from the summary of this invention, various improvement and Of course, changes may be made.

  Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. However, the present invention is not limited to the following examples.

<Physical property evaluation of CNT>
As single-walled CNTs, single-walled CNTs produced by the e-DIPS method (manufactured by Meijo Nanocarbon Co., Ltd., trade name EC) and two kinds of single-walled CNTs produced by a manufacturing method other than the e-DIPS method (produced by KH Chemical Co., Ltd.) , Trade name HP) and (trade name ASP-100F, manufactured by Hanwha-chemical) were prepared.
G / D ratio of the single-walled CNT, the diameter, the peak of RBM absorption 100～120Cm ^-1 and / or 120~140cm ^-1, 250cm ^-1 or more RBM absorption, amorphous carbon amount, and, in the TG / DTA The weight loss starting temperature and the weight loss rate of 600 to 900 ° C. were measured.

<< Measurement of Raman absorption spectrum of single-walled CNT >>
Using a microscopic laser Raman spectrometer (trade name: LabRam HR-800 Evolution, manufactured by Horiba, Ltd.), the Raman spectrum of single-walled CNTs with 532 nm excitation light was measured. From the results obtained Raman spectrum measurement, G / D ratio, the diameter, the main peak existence of RBM absorption 100～120Cm ^-1 and / or 120～140Cm ^-1, the presence or absence of 250 cm ^-1 or more RBM absorption examined It was.
In addition, the G / D ratio and diameter of single-walled CNT were calculated | required by the following.
<<< Calculation of G / D ratio of CNT >>>
A Raman spectrum is measured with excitation light of 532 nm, and the intensity ratio G between the G band (around 1590 cm ⁻¹ , graphene in-plane vibration) and the D band (around 1350 cm ⁻¹ , from sp2 carbon network defects) of each single-walled CNT. The / D ratio was calculated. A large intensity ratio G / D ratio indicates that there are few defects in the carbon nanotube.
<<< Calculation of ring size of carbon nanotube >>>
The diameter was calculated from the radial breathing (RBM) mode shift ω (RBM) (cm ⁻¹ ) using the following formula.
Formula: Diameter (nm) = 248 / ω (RBM)

<< Thermal analysis measurement of CNT >>
Using a thermogravimetric / differential thermal analyzer (trade name TG / DTA 6200 AST-2, manufactured by SII Technology Co., Ltd.), heat was applied to a single-walled CNT at a temperature rising rate of 10 ° C./min and a temperature range of room temperature to 900 ° C. The change in weight was measured.
Moreover, the thermogravimetric change was similarly measured with respect to the CNT coating film after performing the rinse process or the immersion process in the manufacturing process of the transparent conductive laminated body mentioned later.
Furthermore, the CNT coating film which performed the rinse process or the immersion process was taken out, and it measured by the thermogravimetric change in the temperature range of 10 degree-C / min and room temperature-500 degreeC under nitrogen stream regarding the amount of residual dispersing agents.
In addition, the amount of amorphous carbon (AC amount) in the single-walled CNTs was measured from the weight reduction rate of 300 to 500 ° C.
The results are shown in Table 2 described later.

[Examples 1 to 9]
<Preparation of CNT dispersion>
2 g of single-walled CNT by e-DIPS method (manufactured by Meijo Nanocarbon Co., Ltd., trade name EC) was added to 500 ml of concentrated nitric acid (60% by mass, manufactured by Kanto Chemical Co., Ltd.), and heated to reflux at 120 ° C. for 20 hours. After heating to reflux, a nitric acid solution containing CNTs was diluted 3 times with ion-exchanged water and filtered. Washed with ion-exchanged water until the suspension of the filtrate became neutral, and then filtered to obtain a wet CNT body containing water.
To the obtained wet CNT (dry weight 100 mg), 0.3 g of sodium deoxycholate (molecular weight 414.55) and ion-exchanged water were added as a water-soluble dispersant, and the solid content concentration was 1.0 w / v%. Then, using a mechanical homogenizer (manufactured by IKA, trade name: T10 basic), the mixture was mixed at 20 ° C. for 15 minutes to obtain a CNT premix.
Next, this premixed mixture was dispersed in a high-speed swirling thin film for 10 minutes at a peripheral speed of 40 m / sec in a thermostatic layer at 25 ° C. using a thin-film swirling high-speed mixer (trade name: Filmix 40-40, manufactured by PRIMIX Corporation). The CNT paste was prepared by a dispersion process. The dispersion treatment was performed by adjusting the distance between the inner peripheral surface of the “fill mix 40-40” tubular mantle and the outer peripheral surface of the stirring blade to 2 mm.
Next, this CNT paste was diluted with ion-exchanged water so that the CNT concentration became 0.15% by mass. In Examples 2 to 9, 0.5 g of acid or inorganic salt was added as a doping agent. The obtained liquid was centrifuged at 10,000 G for 15 minutes with a high-speed centrifuge (trade name MX-300, manufactured by Tommy Seiko Co., Ltd.) to obtain a CNT dispersion.
Thereafter, water was added to prepare a CNT coating solution by adjusting the final concentration so that the concentration of the CNT aggregate was 0.10% by mass.

<Production of Substrate 12 Having Adhesive Layer 14>
After biaxial stretching that stretches the PET film 3.3 times in the machine direction and transverse direction, the PET film was heat-set at 240 ° C. for 20 seconds, and relaxed by about 4% in the transverse direction at the same temperature. I let you. Thereafter, the chuck portion of the tenter was slitted, and then knurled at both ends and wound up. In this way, a roll-shaped PET substrate having a thickness of 180 μm was obtained.
Next, the produced PET substrate was cut into a sheet shape to obtain a substrate 12.
The substrate 12 was processed at a feed rate of 20 m / min at room temperature using a solid state corona treatment machine (product name: 6KVA model, manufactured by Pillar Co., Ltd.). The processing frequency at this time is 9.6 kHz, the gap clearance between the electrode and the dielectric roller is 1.6 mm, and the substrate is processed at 0.375 kV · A · min / m 2 from the current and voltage readings. It was.
An easy-adhesion solution having the following composition was applied to the treated substrate 12 at 6 ml / m ^{2 and} dried at 185 ° C. for 5 minutes to form an adhesive layer 14 having a thickness of 0.10 μm.
<< Composition of easy adhesive liquid >>
・ Butadiene-styrene copolymer latex (solid content: 43% by mass, butadiene / styrene mass ratio = 32/68): 13 ml
-2,4-dichloro-6-hydroxy-S-triazine sodium salt 8 mass% aqueous solution: 7 ml
Polystyrene particles (average particle size: 1.8 μm) 2% by mass aqueous solution: 0.5 ml
・ Ion exchange water: 79.5 ml

<Preparation of CNT coating film>
The produced CNT coating solution was applied onto the substrate 12 provided with the adhesive layer 14 using a die coater using an extrusion type coating head. Next, the coating film was dried in a dryer at 80 ° C. for 1 minute to immobilize the CNT coating film.
Since the light transmittance varies depending on the coating amount of the CNT coating solution, the coating amount of the CNT coating solution applied to the substrate 12 was adjusted according to the CNT concentration of the coating solution.

<Implementation of rinse treatment or immersion treatment>
In order to remove excess water-soluble dispersant on the substrate 12 on which the adhesive layer 14 and the CNT coating film are formed, the CNT coating film is rinsed with an ethanol solution for 3 minutes, or is immersed in the ethanol solution for 30 seconds. did.
After rinsing or dipping, the droplets adhering to the film were removed with an air duster and then dried at 60 ° C.

<Implementation of heat and pressure treatment>
While applying pressure at 250 kg / cm ² between the nip rolls at a surface temperature of the metal roll of 80 ° C., the substrate 12 on which the adhesive layer 14 and the CNT layer are formed is heated and pressed by passing between the rolls (calendar treatment). Then, CNT was pressure-bonded to the substrate to form a transparent conductive film 16, and a transparent conductive laminate 10 as shown in FIG. 1 was produced.

[Comparative Example 1]
A transparent conductive laminate was produced in the same manner as in Example 1 except that single-walled CNT (manufactured by KH Chemical Co., trade name HP) by a production method other than the e-DIPS method was used as the single-walled CNT.
[Comparative Example 2]
A transparent conductive laminate was produced in the same manner as in Example 2 except that single-wall CNT (manufactured by KH Chemical Co., trade name HP) by a production method other than the e-DIPS method was used as the single-wall CNT.
[Comparative Example 3]
A transparent conductive laminate was prepared in the same manner as in Example 2 except that single-walled CNTs (manufactured by Hanwha-chemical, trade name ASP-100F) by a manufacturing method other than the e-DIPS method were used as the single-walled CNTs. .

[Comparative Example 4]
A transparent conductive laminate was produced in the same manner as in Example 3 except that the immersion treatment was not performed.
[Comparative Example 5]
A transparent conductive laminate was produced in the same manner as in Example 5 except that after the rinsing treatment, no heat and pressure treatment was conducted.

[Evaluation]
About the produced transparent conductive laminated body 10 of Examples 1-9 and Comparative Examples 1-5, the surface resistance value and the light transmittance were measured as follows.
<Surface resistance value>
For the surface resistance value [Ω / □], a resistivity meter (trade name Lorester GP or trade name High Lester UX, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) is used for the transparent conductive laminate 10 sampled to 5 cm × 10 cm. The four-probe probe was brought into close contact with the central portion of the transparent conductive laminate 10 on the transparent conductive film 16 side, and measurement was performed at room temperature by the four-terminal method.
<Light transmittance>
The light transmittance is obtained by allowing light to enter the transparent conductive laminate 10 from the transparent conductive film 16 side with a spectrophotometer (manufactured by Shimadzu Corporation, trade name: UV-3150) and transmitting light at a wavelength of 550 nm [%. ] Was measured.
The results are shown in Table 1.

Table 2 shows the measurement results of the physical properties of each single-walled CNT described above.

As described above, EC (trade name) is a single-walled CNT manufactured by Meijo Nano Carbon Co., Ltd. by the e-DIPS method.
Further, HP (trade name) is a single-walled CNT produced by a manufacturing method other than the e-DIPS method manufactured by KH Chemical. Furthermore, ASP-100F (trade name) is a single-walled CNT produced by a manufacturing method other than the e-DIPS method manufactured by Hanwha-chemical.
Further, for each single-walled CNT, whether or not 50% by mass or more of the CNTs are single-walled CNTs and the diameter is in the range of 1.5 to 2.5 nm is determined according to a high-resolution transmission electron microscope (FEI). Evaluation of 100 CNTs arbitrarily extracted from a visual field in which 10% or more of the visual field area is CNT in a visual field of 1 million times and 150 nm ² in the observation of Titan type, acceleration voltage 80 keV) Confirmed with.
This measurement was performed 5 times while changing the visual field, and an average value of 3 times excluding the maximum value and the minimum value was used.
In addition, when 100 measurement was impossible in one visual field, it measured from the several visual field until it became 100. At this time, if a part of the CNT can be observed in the field of view, it is counted as one, and both ends are not necessarily visible. Moreover, even though it was recognized as two in the field of view, it may be connected outside the field of view and become one, but it was determined to be two.
As a result, EC is CNT in which the content of single-walled carbon nanotubes having a diameter of 1.5 to 2.5 nm is 50% by mass or more, and HP and ASP-100F are 1.5 to 2.5 nm in diameter. It was confirmed that the content of the single-walled carbon nanotube was not CNT having a content of 50% by mass or more.

  From the results of Table 1 and Table 2, the transparent conductive laminate 10 of the present invention in which the transparent conductive film was produced by the production method of the present invention has a lower surface resistance value than the conventional transparent conductive laminate, It can be seen that the light transmittance is excellent.

[Examples 10 to 14, Comparative Examples 6 and 7]
Instead of adding the doping agent (acid or inorganic salt) to the CNT dispersion, Example 2 (Example 10), except that 5 mmol / L (liter) of the doping agent was added to the rinsing treatment solution or the immersion treatment solution. Example 3 (Example 11), Example 4 (Example 12), Example 5 (Example 13), Example 6 (Example 14), Comparative Example 2 (Comparative Example 6), and Comparative Example 3 ( A transparent conductive laminate 10 was prepared in the same manner as in Comparative Example 7).
Regarding the produced transparent conductive laminate 10, the surface resistance value and the light transmittance were measured in the same manner as in Example 1 and the like.
The results are shown in Table 3.

From Table 3, in the manufacturing method of the present invention, the transparent conductive laminate 10 obtained even when the doping agent is added to the rinsing treatment solution or the immersion treatment solution without adding the doping agent to the coating solution. Shows good surface resistance and light transmittance.

[Examples 15 to 17]
Example 2 (Example 15), Example 3 (Example 16), and Example 4 (Example 17), except that the CNT coating film was irradiated with ultraviolet rays before the rinse treatment or the immersion treatment. A transparent conductive laminate 10 was produced in the same manner as described above.
For ultraviolet irradiation, an ultraviolet irradiation machine (trade name ECS-401GX, manufactured by Eye Graphics Co., Ltd.) was used, and the ultraviolet irradiation amount (light quantity) was 300 mJ / cm ² .
Regarding the produced transparent conductive laminate 10, the surface resistance value and the light transmittance were measured in the same manner as in Example 1 and the like.
The results are shown in Table 4 below.

From Table 4, in the manufacturing method of this invention, the surface resistance value of the transparent conductive laminated body 10 obtained by performing an ultraviolet irradiation process to a CNT coating film before removing a water-soluble dispersing agent is further low, and it is favorable. It turns out that it becomes.

[Examples 18 and 19]
The transparent conductive material is the same as in Example 1 (Example 18) and Example 2 (Example 19) except that the adhesive layer 14 is replaced with an alignment film and a rubbing treatment is performed before the CNT coating film is formed. The laminated body 10 was produced.
The formation of the adhesive layer 14 and the rubbing treatment were performed as follows.
First, the surface of the substrate 12 was processed at a feed rate of 20 m / min at room temperature using a solid state corona treatment machine (product name: 6KVA model, manufactured by Pillar Co., Ltd.). Next, an alkyl-modified poval (trade name MP203, manufactured by Kuraray Co., Ltd.) was applied to the substrate 12 as an adhesive layer 14 (alignment film) to a thickness of 1 μm and dried.
Next, using a rubbing machine, the outer diameter of the rubbing roll is 80 mm, the conveyance speed is 100 m / min, the peripheral speed of the rubbing roll is 250 m / min, the film substrate tension is 1 kgf / cm, the substrate width, the wrap angle is 360 °, and the rubbing roll inclination angle α = The adhesive layer 14 was rubbed at 45 °.
Regarding the produced transparent conductive laminate 10, the surface resistance value and the light transmittance were measured in the same manner as in Example 1 and the like.
The results are shown in Table 5 below.

From Table 5, the transparent conductive laminate 10 in which the transparent conductive film 16 is formed on the substrate 12 that has been rubbed with the adhesive layer 14 as an alignment film has a lower surface resistance value because the alignment of the CNTs is promoted. It turns out that it becomes.
From the above results, the effects of the present invention are clear.

  It can be suitably used for touch panels, various displays, electronic paper, and the like.

10 transparent conductive laminate 12 substrate 14 adhesive layer 16 transparent conductive film

Claims (14)

A carbon nanotube with a content of single-walled carbon nanotubes having a diameter of 1.5 to 2.5 nm of 50% by mass or more and a water-soluble dispersant having a molecular weight of 1000 or less are added to an aqueous solvent to disperse the carbon nanotubes. A preparation step of preparing a carbon nanotube dispersion liquid,
A thin film forming step of forming a carbon nanotube thin film by applying the carbon nanotube dispersion liquid to a transparent film substrate and drying the film,
A cleaning step of cleaning the carbon nanotube thin film with a cleaning liquid mainly containing a solvent having an SP value of 10 to 20 to remove the water-soluble dispersant;
And the manufacturing method of the transparent conductive film characterized by having the pressurization process which pressurizes the carbon nanotube thin film which finished the said washing | cleaning process.   The manufacturing method of the transparent conductive film of Claim 1 which performs the said pressurization process with a roller pair or a pressure roller.   The method for producing a transparent conductive film according to claim 2, wherein the pressure in the pressurizing step is 100 to 500 kg / cm.   The manufacturing method of the transparent conductive film of any one of Claims 1-3 which heats the member which pressurizes the said carbon nanotube thin film to 60-100 degreeC in the said pressurization process.   The method for producing a transparent conductive film according to claim 1, wherein the cleaning liquid contains an acid having a pKa of 5 or less or an inorganic salt having a standard oxidation potential of 1 V or less.   The said washing | cleaning process removes a water-soluble dispersing agent until the quantity of the water-soluble dispersing agent in the said carbon nanotube thin film becomes 20 mass% or less with respect to the said carbon nanotube. 2. A method for producing a transparent conductive film according to item 1.   The transparent conductive film according to any one of claims 1 to 6, wherein the pressurizing step is performed after the carbon nanotube thin film that has finished the cleaning step is irradiated with any one of ultraviolet light, visible light, and infrared light. Production method.   The method for producing a transparent conductive film according to claim 1, wherein the transparent film substrate has an adhesive layer on a surface thereof.   The method for producing a transparent conductive film according to claim 8, wherein the adhesive layer is an alignment film.   The method for producing a transparent conductive film according to claim 9, further comprising a step of rubbing the adhesive layer to form an alignment film before the thin film forming step. A transparent conductive material having an adhesive layer on a transparent film-like substrate and containing a carbon nanotube having a diameter of 1.5 to 2.5 nm of single-walled carbon nanotubes of 50% by mass or more on the adhesive layer Having a membrane, and
The carbon nanotubes, the ratio is 100 or more and the peak intensity and the 1350 peak intensity of ± 40 cm ^-1 of 1590 ± 50 cm ^-1 by Raman spectroscopy in the wavelength 532 nm; the content of the amorphous carbon 3 mass% or less; from room 900 In thermogravimetry up to 0 ° C., the weight loss starting temperature is 600 ° C. or more and the weight loss is 90 to 99% by mass; and at the peak in the RBM region by Raman spectroscopy at a wavelength of 532 nm, 100 to 120 cm ⁻¹ and it has a main peak in at least one of 120～140Cm ^-1, and a peak is not in the 250 cm ^-1 or more; four conditions of the transparent conductive laminate and satisfies simultaneously.   The transparent conductive laminate according to claim 11, wherein the transparent conductive film contains an acid having a pKa of 5 or less, or an inorganic salt having a standard oxidation potential of 1 V or less.   The transparent conductive laminate according to claim 11 or 12, wherein the adhesive layer is an alignment film.   The transparent conductive film contains a water-soluble dispersant having a molecular weight of 1000 or less, and the content of the water-soluble dispersant is 20% by mass or less based on carbon nanotubes. The transparent conductive laminate described.