JP2017065053A - Conductive laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive laminate having excellent stability of a resistance value in a high-temperature humidified environment.SOLUTION: The conductive laminate has a conductive layer comprising carbon nanotube on at least one surface of a substrate and satisfies the following conditions (1) and (2). (1) A surface resistance value ratio [B]/[A], where [A] is a surface resistance value before a high-temperature humidification test (at 85°C and 85% relative humidity for 500 hours) is carried out and [B] is a surface resistance value after the high-temperature humidification test, is 1.40 or less. (2) A haze difference [D]-[C], where [C] is a haze before a high-temperature humidification test (at 85°C and 85% relative humidity for 500 hours) is carried out and [D] is a haze after the high-temperature humidification test, is 0.1 or more and 5.0 or less.SELECTED DRAWING: None

Description

  The present invention relates to a conductive laminate. More specifically, the present invention relates to a conductive laminate excellent in resistance value stability and appearance under high temperature and high humidity.

  Conventionally, conductive laminates have been used for various products such as touch panel applications such as resistive film type and capacitance type, electronic paper applications, and digital signage applications. Indium tin oxide (hereinafter referred to as ITO), silver nanowires (hereinafter referred to as AgNW), carbon nanotubes (hereinafter referred to as CNT), conductive polymers, and the like are used as a conductive material for developing conductivity.

  CNTs are expected to be used as conductive materials because they themselves have excellent intrinsic conductivity and are stable against heat and humidity. The CNT has a substantially cylindrical shape by winding one surface of graphite, and a single-layer CNT is wound in one layer, a multi-layer CNT is wound in multiple layers, especially two layers. This was called double-walled CNT.

  For example, Patent Document 1 describes an example in which a carbon nanotube layer is formed and then washed with water to remove sodium dodecylbenzenesulfonate as an ionic dispersant.

  Patent Document 2 describes an example of a conductive laminate including polythiophene as a separated layer after forming a carbon nanotube layer.

Patent No. 5409094 Japanese Patent No. 5554552

  However, in Patent Document 1, there is a description that the ionic dispersant on the substrate is sufficiently removed by washing with water, but there is no specific description of resistance value stability against high temperature humidification.

  In Patent Document 2, a conductive polymer polythiophene having a large change in electrical characteristics when placed in a high-temperature and high-humidity environment is used, and no specific description regarding resistance value stability to high-temperature and humidity is found.

  This invention is made | formed in view of the said problem and the situation, The subject is providing the conductive laminated body excellent in resistance value stability and external appearance under high temperature, high humidity.

  The present invention provides the following conductive laminate.

A conductive laminate having a conductive layer containing carbon nanotubes on at least one surface of a substrate, the conductive laminate satisfying the following (1) and (2).
(1) Surface resistance value when [A] is the surface resistance value before the high temperature humidification test (85 ° C., 85% relative humidity, 500 hours) and [B] is the surface resistance value after the high temperature humidification test is performed. The ratio [B] / [A] is 1.40 or less.
(2) Haze difference [D] − [H] before the high temperature humidification test (85 ° C., relative humidity 85%, 500 hours) is [C] and haze after the high temperature humidification test is [D]. C] is 0.1 or more and 5.0 or less.

  According to the present invention, it is possible to provide a conductive laminate excellent in resistance value stability and appearance under high temperature and high humidity.

It is a section schematic diagram showing an example of a conductive layered product in the present invention.

The present invention relates to a conductive laminate having a conductive layer containing carbon nanotubes on at least one surface of a base material and satisfying the following (1) and (2).
(1) Surface resistance value when [A] is the surface resistance value before the high temperature humidification test (85 ° C., 85% relative humidity, 500 hours) and [B] is the surface resistance value after the high temperature humidification test is performed. The ratio [B] / [A] is 1.40 or less.
(2) Haze difference [D] − [H] before the high temperature humidification test (85 ° C., relative humidity 85%, 500 hours) is [C] and haze after the high temperature humidification test is [D]. C] is 0.1 or more and 5.0 or less.

  By having such a configuration, the conductive laminate of the present invention can improve resistance value stability and appearance under high-temperature humidification of the device when the conductive laminate is used in an electronic device.

[Conductive laminate]
The conductive laminate of the present invention includes at least a base material and a conductive layer containing carbon nanotubes. That is, it is a conductive laminate having a conductive layer containing carbon nanotubes on at least one surface of the substrate, and satisfying the following (1) and (2).
(1) Surface resistance value when [A] is the surface resistance value before the high temperature humidification test (85 ° C., 85% relative humidity, 500 hours) and [B] is the surface resistance value after the high temperature humidification test is performed. The ratio [B] / [A] is 1.40 or less.
(2) Haze difference [D] − [H] before the high temperature humidification test (85 ° C., relative humidity 85%, 500 hours) is [C] and haze after the high temperature humidification test is [D]. C] is 0.1 or more and 5.0 or less.

  The ratio [B] / [A] of the surface resistance value after the high-temperature humidification test is 1.40 or less, and the difference [D]-[C] in the haze is 0.1 or more and 5.0 or less, whereby the touch panel When it is used for a touch switch or the like, the resistance value stability and the appearance are good, which is preferable.

  Moreover, you may provide functional layers, such as an overcoat layer, on an undercoat layer or a conductive layer between a base material and a conductive layer as needed for an interlayer adhesive improvement or a reliability improvement.

[Base material]
As a base material used for this invention, the haze before a high temperature humidification test (85 degreeC, relative humidity 85%, 500 hours) implementation is [E], and the haze after implementation of a high temperature humidification test is [F]. The difference [F]-[E] is preferably 0.1 or more and 5.0 or less.

  For example, as a material of the base material, polyester resin such as polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN), polycarbonate (PC) resin, polymethyl methacrylate (PMMA) resin, polyimide resin, polyphenylene sulfide resin, aramid resin, Polypropylene resin, polyethylene resin, polylactic acid resin, polyvinyl chloride resin, polymethyl methacrylate resin, alicyclic acrylic resin, cycloolefin resin, triacetyl cellulose resin, and the like can be used.

  The substrate used in the present invention preferably has a glass transition point of 85 ° C. or higher. From the viewpoint of increasing haze, it is most preferable to include a polycarbonate resin. The base material may be made only of polycarbonate (PC) resin, or may contain polycarbonate (PC) resin and other resins.

  Moreover, these several base materials can also be used in combination. For example, a composite substrate such as a substrate in which a resin and glass are combined and a substrate in which two or more kinds of resins are laminated may be used. As the glass, ordinary soda glass can be used.

  The type of the substrate is not limited to the above, and an optimal one can be selected from the durability, cost, etc. according to the application. Although the thickness of a base material is not specifically limited, When using for electrodes related to displays, such as a touch panel, a liquid crystal display, organic electroluminescence, and electronic paper, it is preferable that it is between 10 micrometers-1,000 micrometers.

  Various functional layers, such as a hard-coat layer, can also be provided to a base material as needed. The hard coat layer can be provided on the outermost layer on the side opposite to the side where the conductive layer is provided with the substrate interposed therebetween. The hard coat layer is provided mainly for improving the surface strength, antifouling property, fingerprint resistance and the like, and can further impart antiglare property by forming fine irregularities on the surface. As the hard coat layer, a thermosetting acrylic resin or an ultraviolet curable acrylic resin is preferably used from the viewpoint of excellent properties such as transparency and hardness when cured. In this case, the hard coat layer is regarded as a part of the substrate.

[Conductive layer]
The “conductive layer” in the present invention refers to a layer containing carbon nanotubes to be described later. When there is an undercoat layer to be described later, the undercoat layer is also included in the conductive layer. Furthermore, when there is an overcoat layer described later, the overcoat layer is also included in the conductive layer. In the present invention, the thickness of the conductive layer is preferably 20 nm or more and 2,000 nm or less. From the viewpoint of conductivity and weather resistance, it is more preferably from 50 nm to 1,500 nm, and further preferably from 100 nm to 1,000 nm.

  Moreover, it is preferable that pencil hardness is H-9H from a viewpoint that the conductive layer of this invention can suppress oligomer precipitation from the base material under high temperature humidification, and can suppress a haze value raise.

[Method for producing conductive layer]
In the present invention, for example, the conductive layer is produced by laminating a layer containing carbon nanotubes on a substrate. Alternatively, a layer containing carbon nanotubes may be formed after the undercoat layer is formed on the substrate. Further, an overcoat layer may be further laminated after forming a layer containing carbon nanotubes. Since the overcoat layer may penetrate into the carbon nanotube-containing layer and the undercoat layer and form a layer in a mixed state, there is a clear interface between the carbon nanotube-containing layer, the undercoat layer, and the overcoat layer. May not exist.

[carbon nanotube]
The carbon nanotube used in the present invention is not particularly limited as long as it has a shape obtained by winding one surface of graphite into a cylindrical shape. Single-wall carbon in which one surface of graphite is wound in one layer. Both nanotubes and multi-walled carbon nanotubes wound in multiple layers can be used, but in particular, carbon nanotubes in which 50 or more double-walled carbon nanotubes in which one surface of graphite is wound in two layers are contained in 100 are conductive. And the dispersibility of the carbon nanotubes in the coating dispersion is extremely high. More preferably, 75 or more of 100 are double-walled carbon nanotubes, and most preferably 80 or more of 100 are double-walled carbon nanotubes. In addition, the fact that 50 of the double-walled carbon nanotubes are contained in 100 may be expressed as 50% of the double-walled carbon nanotubes. In addition, the double-walled carbon nanotube is preferable from the viewpoint that the original functions such as conductivity are not impaired even when the surface is functionalized by acid treatment or the like.

  For example, the carbon nanotube is manufactured as follows. A powdery catalyst in which iron is supported on magnesia is present in the entire horizontal cross-sectional direction of the reactor in a vertical reactor, and methane is supplied in the vertical direction into the reactor. The carbon nanotubes containing single- to five-layer carbon nanotubes can be obtained by contacting the carbon nanotubes at 200 ° C. to produce carbon nanotubes and then oxidizing the carbon nanotubes. Carbon nanotubes can be oxidized and then subjected to an oxidation treatment to increase the ratio of single to 5 layers, particularly the ratio of 2 to 5 layers. The oxidation treatment is performed, for example, by a nitric acid treatment method. Nitric acid is preferable because it also acts as a dopant for the carbon nanotubes. A dopant is a substance that gives a surplus electron to a carbon nanotube or takes away an electron to form a hole, and improves the conductivity of the carbon nanotube by generating a carrier that can move freely. Is. The conditions for the nitric acid treatment are not particularly limited as long as the carbon nanotubes of the present invention can be obtained, but are usually performed in an oil bath at 140 ° C. Although the nitric acid treatment time is not particularly limited, it is preferably in the range of 5 hours to 50 hours.

[Undercoat layer]
In this invention, it is preferable to have an undercoat layer between the said base material and the said conductive layer (Hereinafter, forming an undercoat layer may be described as an undercoat process.). By performing the undercoat treatment, it is possible to suppress the amount of oligomer generated from the base material during the high-temperature humidification test. As a result, the network of the carbon nanotube layer is not destroyed, and the change in the surface resistance value and haze is small. Therefore, it is preferable. As a material used for the undercoat treatment, an organic material, an inorganic material, or an organic material / inorganic material mixed system can be used. Here, it is preferable that the pencil hardness of the undercoat layer is H to 9H from the viewpoint that the hardness is high and oligomer precipitation can be suppressed.

  As the inorganic material, for example, those composed of silica, colloidal silica, alumina, ceria, kaolin, talc, mica, calcium carbonate, barium sulfate, carbon black, zeolite, titanium oxide, and various metal oxides are preferable. The organic material contained in the undercoat layer is an organic compound having a covalent bond and having a molecule composed of two or more types of atoms as a minimum unit. As the organic material, for example, phenol, silicon, nylon, polyethylene, polyester, olefin, vinyl, acrylic, cellulose, urethane acrylate, and the like are preferable. From the viewpoint of increasing haze, a polycarbonate resin is most preferable.

  In the present invention, the method for performing the overcoat treatment is not particularly limited. Known wet coating methods such as spray coating, dip coating, spin coating, knife coating, kiss coating, roll coating, gravure coating, slot die coating, bar coating, screen printing, inkjet printing, pad printing, other types of printing, etc. Is available. Further, a dry coating method may be used. As the dry coating method, physical vapor deposition such as sputtering or vapor deposition, chemical vapor deposition, or the like can be used. The operation for performing the overcoat treatment may be performed in a plurality of times, or two different methods may be combined. Preferred methods are wet coatings such as gravure coating, bar coating, and slot die coating.

[Overcoat layer]
In the present invention, it is preferable to have an overcoat layer on the conductive layer. By forming the overcoat layer on the conductive layer, the amount of oligomer generated from the substrate during the high-temperature humidification test can be suppressed. As a result, the network of the carbon nanotube layer is not destroyed and the surface resistance value is reduced. And a change in haze is small, which is preferable. As a material used for the overcoat layer, an organic material, an inorganic material, or an organic material / inorganic material mixed system can be used. Here, it is preferable that the pencil hardness of the overcoat layer is H to 9H because the hardness is high and oligomer precipitation can be suppressed.

  The inorganic material is not particularly limited, but for example, those composed of silica, colloidal silica, alumina, ceria, kaolin, talc, mica, calcium carbonate, barium sulfate, carbon black, zeolite, titanium oxide, and various metal oxides are preferable. Among these, silica and colloidal silica are most preferable from the viewpoint of applicability.

  The organic material contained in the overcoat layer is an organic compound having a covalent bond and having a molecule composed of two or more types of atoms as a minimum unit. The organic material is not particularly limited, but for example, phenol resin, silicon resin, nylon resin, polyethylene resin, polyester resin, olefin resin, vinyl resin, acrylic resin, cellulose resin, and urethane acrylate resin are preferable. Among these, an acrylic resin is most preferable from the viewpoint of the degree of curing.

  As the organic material / inorganic material mixed system, a mixed form of the inorganic material and the organic material can be used. Among these, colloidal silica / polyester resin and colloidal silica / acrylic resin are most preferable from the viewpoint of compatibility.

[Undercoat layer formation process]
In the present invention, the method for forming the overcoat layer containing the resin composition is not particularly limited. Known wet coating methods such as spray coating, dip coating, spin coating, knife coating, kiss coating, roll coating, gravure coating, slot die coating, bar coating, screen printing, inkjet printing, pad printing, other types of printing, etc. Is available. Further, a dry coating method may be used. As the dry coating method, physical vapor deposition such as sputtering or vapor deposition, chemical vapor deposition, or the like can be used. The operation for performing the overcoat treatment may be performed in a plurality of times, or two different methods may be combined. Preferred methods are wet coatings such as gravure coating, bar coating and slot die coating. The coating amount of the overcoat containing the resin composition can be controlled by adjusting the solid content concentration of the overcoat solution and the wet thickness when the overcoat solution is applied.

[Overcoat layer forming step]
In the present invention, the method for forming the overcoat layer containing the resin composition is not particularly limited. Known wet coating methods such as spray coating, dip coating, spin coating, knife coating, kiss coating, roll coating, gravure coating, slot die coating, bar coating, screen printing, inkjet printing, pad printing, other types of printing, etc. Is available. Further, a dry coating method may be used. As the dry coating method, physical vapor deposition such as sputtering or vapor deposition, chemical vapor deposition, or the like can be used. The operation for performing the overcoat treatment may be performed in a plurality of times, or two different methods may be combined. Preferred methods are wet coatings such as gravure coating, bar coating and slot die coating. The coating amount of the overcoat containing the resin composition can be controlled by adjusting the solid content concentration of the overcoat solution and the wet thickness when the overcoat solution is applied.

[Transparent conductivity]
As described above, a conductive laminate having excellent resistance value stability under high humidity can be obtained. Transparent conductivity means having both transparency and conductivity. The intersurface resistance value is used as the conductivity index, and the lower the intersurface resistance value, the higher the electrical conductivity. As an index of transparency, there is a carbon nanotube layer light absorptivity (hereinafter sometimes simply referred to as “light absorptance”). The carbon nanotube layer optical absorptance is an index represented by the following formula at a wavelength of 550 nm.

  Carbon nanotube layer light absorption rate (550 nm) = 100−total light transmittance (550 nm) −relative reflectance (550 nm).

  A typical index of transparency is a light absorptivity, and the light absorptivity of a conductive laminate including one conductive layer has a practical meaning.

Also, typical indicators of conductivity are the surface resistance value and inter-terminal resistance value of the conductive laminate, and the surface resistance value and inter-terminal resistance value of the conductive laminate including one conductive layer are practical. There is a meaning. The surface resistance value and the terminal resistance value can be converted by the following formula.
Surface resistance [Ω / □] = resistance between terminals [Ω] × width between electrodes [mm] ÷ length between electrodes [mm].
The inter-terminal resistance value can be measured by forming an electrode such as silver paste on the conductive laminate and measuring the terminal resistance value between them with a tester or the like.

  Such conductivity (surface resistance value and inter-terminal resistance value) and transparency (carbon nanotube layer light absorption rate) can be adjusted by the coating amount of carbon nanotubes. However, when the coating amount of the carbon nanotube is small, the conductivity is low, while the transparency is high. When the coating amount is large, the conductivity is high, but the transparency is low. That is, both are in a trade-off relationship, and it is difficult to satisfy both. Because of this relationship, in order to compare the transparent conductivity, it is necessary to fix one index and then compare the other index.

[Surface resistance value under high humidity and humidity]
As a method for measuring resistance value stability under high humidity and humidity, it is preferable to measure the surface resistance value in an environment in which humidity and humidity are controlled. For example, the conductive laminate is placed in a constant temperature and humidity chamber capable of keeping temperature and humidity constant, and the surface resistance value under constant temperature and humidity conditions is measured. The humidity range is preferably measured in the range of 25 to 100 ° C. and in the range of 0 to 100% relative humidity, and most preferably in the range of 85% relative humidity at a constant temperature of 85 ° C. The measurement time is preferably left until the surface resistance value of the conductive laminate becomes constant from the viewpoint of stability measurement.

[Usage]
The conductive laminate of the present invention can be preferably used for electronic paper because it has high uniformity in the dispersion state of carbon nanotubes and can apply a voltage uniformly. In addition, since the dispersion state of carbon nanotubes is high and the drawing durability is excellent, it can be preferably used for a touch panel. Furthermore, it can be preferably used as an electrode related to a display such as a liquid crystal display and organic electroluminescence, and an electrode for a transparent sheet heating element.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. The measurement method used in this example is shown below.

  In addition, (i) surface resistance value [A] of conductive laminate before carrying out high temperature humidification test (85 ° C., relative humidity 85%, 500 hours), (ii) haze [C] and (iii) group of conductive laminate The haze [E] of the material was a value measured after holding each sample for 24 hours at a temperature of 25 ° C. and a relative humidity of 30%.

(1) Weight average molecular weight of dispersant The weight average molecular weight of the dispersant was calculated by comparing with a calibration curve with polyethylene glycol using a gel permeation chromatography method.
Apparatus: LC-10A series manufactured by Shimadzu Corporation Column: GF-7M HQ manufactured by Showa Denko KK
Mobile phase: 10 mmol / L Lithium bromide aqueous solution Flow rate: 1.0 ml / min
Detection: differential refractometer column temperature: 25 ° C.

(2) Surface resistance value Using a non-contact type resistivity meter (NC-10, NC-10) at the center of the conductive laminate cut to a size of 100 mm x 50 mm, the value measured by the eddy current method is The surface resistance value [A] before the high-temperature humidification test (85 ° C., relative humidity 85%, 500 hours) was carried out.

(3) Haze value The haze of the conductive laminate was measured using a turbidimeter NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd. based on JIS K 7361 (1997). In addition, it measured similarly about the haze of the base material.

(4) 85 ° C., relative humidity 85% test The prepared conductive laminate was placed in a small environmental tester (Espec Corp., SH-221) and held at a temperature of 85 ° C. and a relative humidity of 85% RH for 500 hours. After the high temperature humidification test, the stable surface resistance value after holding for 24 hours at a temperature of 25 ° C. and a relative humidity of 30% is the surface resistance value after the high temperature humidification test (85 ° C., relative humidity 85%, 500 hours) [B ]. Further, after the high temperature humidification test, the stable haze after being held at a temperature of 25 ° C. and a relative humidity of 30% for 24 hours is referred to as haze [D] after the high temperature humidification test (85 ° C., relative humidity of 85%, 500 hours). did. In addition, it measured similarly about the haze [F] of the base material after a high temperature humidification test (85 degreeC, 85% of relative humidity).

(5) Pencil hardness measurement method The pencil hardness of each of the undercoat layer, the conductive layer, and the overcoat layer was measured by the following method. The pencil hardness of the undercoat layer was measured after the undercoat layer was formed. If there is no overcoat, measure the pencil hardness on the surface of the conductive layer, and use that value as the pencil hardness of the conductive layer. If there is an overcoat layer, measure the pencil hardness on the surface of the conductive layer on which the overcoat layer is formed. The value was taken as the pencil hardness of the overcoat layer.

  Using “HEIDON-14DR” (manufactured by Shinto Kagaku Co., Ltd.), each surface of the conductive layer on which the undercoat layer, conductive layer or overcoat layer of the conductive laminate was formed (hereinafter referred to as the resin layer surface) had each hardness. Another pencil was placed in contact. Next, according to JIS "Scratch hardness (pencil method)" (K5600-5-4, 2008 edition), the pencil was moved at a load of 750 g, a speed of 30 mm / min, and a moving distance of 10 mm. The measurement was carried out by successively increasing the hardness of the pencil until a scratch mark having a length of 3 mm or more was generated on the resin layer side surface of the conductive laminate. The pencil hardness of the resin layer was defined as the hardness of the pencil in front of which scratch marks were formed on the resin layer side surface of the conductive laminate.

Example 1
[Preparation of undercoat layer]
The coating liquid for undercoat layer preparation was adjusted with the following procedures. An aqueous dispersion of hydrophilic acrylic-modified polyester resin (“Pesresin A647-GEX” manufactured by Takamatsu Yushi Co., Ltd., solid content concentration: 20% by mass) is used as the resin for the undercoat layer, and an aqueous dispersion of silica particles (Nissan Chemical Industries, Ltd.) “Snowtex OUP” solid content concentration: 15% by mass) was used as the silica particles contained in the undercoat layer. The pesresin A647-GEX, Snowtex OUP, and pure water were mixed at a mass ratio of 2.6: 10.9: 1.5 to obtain a coating solution for preparing an undercoat layer having a solid content of 5% by mass. A 100 μm thick biaxially stretched polyethylene terephthalate (PET) film provided with “Tough Top” THS manufactured by Toray Film Processing Co., Ltd. as a hard coat layer on the back surface of the base material “Lumirror” (registered trademark) U48 manufactured by Toray Industries, Inc. used. Using a UR100 line gravure roll, the rotation ratio of the gravure roll with respect to the line speed was set to 1.5 times, and the coating liquid for the undercoat layer was applied onto the substrate. After coating, the film was dried in a dryer at 125 ° C. for 1 minute. The thickness of the undercoat layer produced by this method was about 800 nm, and the mass ratio of the resin and silica particles in the undercoat layer was 7: 3. The pencil hardness of the undercoat layer was HB.

[Preparation of carbon nanotube synthesis catalyst]
About 24.6 g of iron (III) ammonium citrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 6.2 kg of ion-exchanged water. About 1,000 g of magnesium oxide (MJ-30 manufactured by Iwatani Corporation) was added to this solution, and after vigorously stirring for 60 minutes with a stirrer, the suspension was introduced into a 10 L autoclave container. At this time, 0.5 kg of ion exchange water was used as a washing solution. In a sealed state, it was heated to 160 ° C. and held for 6 hours. Thereafter, the autoclave container was allowed to cool, the slurry-like cloudy substance was taken out from the container, excess water was filtered off by suction filtration, and a small amount of water contained in the filtered material was dried by heating in a 120 ° C. drier. The obtained solid content was collected on a sieve and the particle size in the range of 10 to 20 mesh was recovered while being finely divided in a mortar. The granular catalyst body shown on the left was introduced into an electric furnace and heated at 600 ° C. for 3 hours in the atmosphere. The bulk density was 0.32 g / mL. Further, when the filtrate was analyzed by an energy dispersive X-ray analyzer (EDX), iron was not detected. From this, it was confirmed that the added iron (III) ammonium citrate was supported on the entire amount of magnesium oxide. Furthermore, from the EDX analysis result of the catalyst body, the iron content contained in the catalyst body was 0.39% by mass.

[Production of carbon nanotubes]
Carbon nanotubes were synthesized using the catalyst. A catalyst layer was prepared by taking 132 g of the solid catalyst and introducing it onto a quartz sintered plate at the center of the reactor installed in the vertical direction. While heating the catalyst layer until the temperature in the reaction tube reaches about 860 ° C., nitrogen gas is supplied from the bottom of the reactor toward the top of the reactor at 16.5 L / min so as to pass through the catalyst layer. Circulated. Thereafter, while supplying nitrogen gas, methane gas was further introduced at 0.78 L / min for 60 minutes and aeration was performed so as to pass through the catalyst body layer to cause a reaction. The introduction of methane gas was stopped, and the quartz reaction tube was cooled to room temperature while supplying nitrogen gas at 16.5 L / min to obtain a carbon nanotube composition with a catalyst. 129 g of this catalyst-attached carbon nanotube composition was stirred in 4.8 mL of a 4.8N hydrochloric acid aqueous solution for 1 hour to dissolve the catalyst metal iron and the carrier MgO. The obtained black suspension was filtered, and the filtered product was again put into 400 mL of a 4.8N hydrochloric acid aqueous solution, treated with MgO, and collected by filtration. This operation was repeated three times to obtain a carbon nanotube composition from which the catalyst was removed.

[Oxidation treatment of carbon nanotubes]
The carbon nanotube composition was added to concentrated nitric acid (primary assay 60-61 mass% manufactured by Wako Pure Chemical Industries, Ltd.) having a mass of about 300 times. Thereafter, the mixture was heated to reflux with stirring in an oil bath at about 140 ° C. for 24 hours. After heating to reflux, the nitric acid solution containing the carbon nanotube-containing composition was diluted twice with ion-exchanged water and suction filtered. The carbon nanotube composition was stored in a wet state containing water after washing with ion-exchanged water until the suspension of the filtered material became neutral. When the average outer diameter of the carbon nanotube composition was observed with a high-resolution transmission electron microscope, it was 1.7 nm. The proportion of double-walled carbon nanotubes was 90% by mass, the Raman G / D ratio measured at a wavelength of 532 nm was 80, and the combustion peak temperature was 725 ° C.

[Production of Carboxymethyl Cellulose with Weight Average Molecular Weight: 35,000]
10 mass% sodium carboxymethylcellulose (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen 5A (weight average molecular weight: 80,000, molecular weight distribution (Mw / Mn): 1.6, degree of etherification: 0.7)) aqueous solution 500 g was added to a three-necked flask and adjusted to pH 2 using primary sulfuric acid (Kishida Chemical Co., Ltd.). This container was transferred to an oil bath heated to 120 ° C., and subjected to a hydrolysis reaction for 9 hours with stirring under heating and reflux. After allowing the three-necked flask to cool, the reaction was stopped by adjusting the pH to 10 using a 28% by mass aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.). The weight average molecular weight of the sodium carboxymethylcellulose after hydrolysis was calculated by comparing with a calibration curve with polyethylene glycol using a gel permeation chromatography method. As a result, the weight average molecular weight was about 35,000, and the molecular weight distribution (Mw / Mn) was 1.5. The yield was 97% by mass. Dialysis tube (Spectral Laboratories, Biotech CE dialysis tube (fractionated molecular weight: 3,500-5,000D) obtained by cutting 20 g of 10% by weight aqueous sodium carboxymethylcellulose (weight average molecular weight: 35,000) into 30 cm. In addition, the dialysis tube was floated in a beaker containing 1,000 g of ion-exchanged water and dialyzed for 2 hours, and then dialyzed again for 2 hours after replacing with 1,000 g of new ion-exchanged water. After repeating this operation three times, dialysis was carried out for 12 hours in a beaker containing 1,000 g of new ion-exchanged water, and an aqueous sodium carboxymethylcellulose solution was taken out from the dialysis tube, which was concentrated under reduced pressure using an evaporator. Dry using a freeze dryer As a result, powdered sodium carboxymethylcellulose was obtained with a yield of 70% by mass, the weight average molecular weight by gel permeation chromatography was the same as that before dialysis, and the peak in gel permeation chromatography spectrum. The area of sodium carboxymethylcellulose before dialysis was 57% by mass, whereas the peak area of ammonium sulfate decreased after dialysis, and the peak area of carboxymethylcellulose sodium was improved to 91% by mass.

[Preparation of carbon nanotube dispersion]
Using this 10% by mass aqueous sodium carboxymethylcellulose (weight average molecular weight: 35,000) aqueous solution, the carbon nanotube-containing composition in a wet state (25 mg in terms of dry mass), 3.5% by mass sodium carboxymethylcellulose (Daiichi Kogyo Seiyaku ( 1.8 g of aqueous solution hydrolyzed by serogen 5A (weight average molecular weight: 35,000), zirconia beads (manufactured by Toray Industries, Inc., “Traceram” (registered trademark)), bead size: 0.8 mm 13.3 g was added to the container, and the pH was adjusted to 10 using a 28% by mass aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.). When this container was shaken for 2 hours using a vibration ball mill (manufactured by Irie Trading Co., Ltd., VS-1, frequency: 1,800 cpm (60 Hz)), a carbon nanotube paste was prepared. The amount of the dispersant adsorbed in the paste was 88% by mass, and the particle size was 2.9 μm.

  Next, this carbon nanotube-containing composition paste was diluted with ion-exchanged water so that the concentration of the carbon nanotube-containing composition was 0.15% by mass, and again adjusted to pH 10 with 28% by mass ammonia aqueous solution with respect to 10 g of the diluted solution. It was adjusted. The aqueous solution was subjected to a dispersion treatment under ice-cooling with an ultrasonic homogenizer (manufactured by Ieda Trading Co., Ltd., VCX-130) output 20 W, 1.5 minutes (2 kW · min / g). The liquid temperature during dispersion was adjusted to 10 ° C. or lower. The obtained liquid was centrifuged at 10,000 G for 15 minutes with a high-speed centrifuge (Tomy Seiko Co., Ltd., MX-300) to obtain 9 g of a carbon nanotube dispersion. The average diameter of the dispersion of the carbon nanotube-containing composition as measured by AFM in the dispersion was 1.7 nm and was isolated and dispersed. The length of the carbon nanotube-containing composition dispersion was 3.9 μm. Then, water was added and it prepared so that the density | concentration of a carbon nanotube containing composition might be 0.06 mass% by final concentration, and it was set as the film coating liquid.

[Production of a layer containing carbon nanotubes]
The film coating solution produced by the production method was applied onto the undercoat layer by a bar coating method and dried to produce a layer containing carbon nanotubes. The number of the bar coat is No. 6, the drying temperature is 100 ° C. and the drying time is 60 seconds.

[Preparation of overcoat layer]
Acrylic resin (“Kyoeisha Chemical Co., Ltd.“ Light Acrylate DPE-6A ”) is diluted with a solvent in which isopropyl alcohol and ethyl acetate are mixed at a mass ratio of 7: 3 to a solid content concentration of 2.0 mass%, and photopolymerization is performed. An initiator (“IRGACURE 184” manufactured by BASF) was added in an amount of 5% by mass with respect to the resin solid content to obtain an overcoat coating solution. This coating solution was applied onto the layer containing carbon nanotubes with a bar coater number 8 and dried at 125 ° C. for 1 minute using a hot air oven. Furthermore, UV irradiation was performed using a UV irradiation apparatus (“ECS-301” manufactured by Eye Graphics Co., Ltd.) at a dose of 400 mJ / cm ^{2 in} a nitrogen atmosphere to form an overcoat layer. The pencil hardness of the overcoat layer was 3H.

(Example 2)
A conductive laminate was produced in the same manner as in Example 1 except that the UV irradiation condition during the production of the overcoat layer was changed to an integrated light quantity of 100 mJ / cm ² under a nitrogen atmosphere. The pencil hardness of the overcoat layer was H.

(Example 3)
A polycarbonate film having a thickness of 100 μm (“Iupilon E2000” manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was used as the substrate. Corona treatment was performed as a substrate surface treatment. This treatment increased the hydrophilicity of the substrate surface and lowered the water contact angle to 60-70 °. A layer containing carbon nanotubes and an overcoat layer were produced in the same manner as in Example 1. The pencil hardness of the overcoat layer was 3H.

Example 4
An undercoat layer was prepared by the following operation. An aqueous dispersion of polyurethane resin (“Superflex 150” solid content concentration: 30% by mass manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the resin for the undercoat layer, and an aqueous dispersion of silica particles (“Nissan Chemical Industries, Ltd.“ “Snowtex OUP” (solid content concentration: 15 mass%) was used as the silica particles contained in the undercoat layer. Superflex 150, Snowtex OUP, and pure water were mixed at a mass ratio of 5.25: 4.5: 5.25 to obtain a coating solution for preparing an undercoat layer having a solid content of 15% by mass. A polycarbonate film having a thickness of 100 μm (“Iupilon E2000” manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was used as the substrate. Using a UR100 line gravure roll, the rotation ratio of the gravure roll with respect to the line speed was set to 1.5 times, and the coating liquid for the undercoat layer was applied onto the substrate. After coating, the film was dried in a dryer at 125 ° C. for 1 minute. The thickness of the undercoat layer produced by this method was about 800 nm, and the mass ratio of the resin and silica particles in the undercoat layer was 7: 3. The pencil hardness of the undercoat layer was B. A layer containing carbon nanotubes and an overcoat layer were produced in the same manner as in Example 1. The pencil hardness of the overcoat layer was 3H.

(Example 5)
A conductive laminate was produced in the same manner as in Example 4 except that the UV irradiation condition during the production of the overcoat layer was changed to an integrated light quantity of 100 mJ / cm ² under a nitrogen atmosphere. The pencil hardness of the overcoat layer was H.

(Example 6)
PET with double-sided hard coat (FHC-S8W manufactured by Higashiyama Film Co., Ltd.) was used as the substrate. The pencil hardness of the hard coat layer was 3H. Corona treatment was performed as a substrate surface treatment. This treatment increased the hydrophilicity of the substrate surface and lowered the water contact angle to 62 °. A layer containing carbon nanotubes was produced in the same manner as in Example 1. The pencil hardness of the undercoat layer was 3H.

(Comparative Example 1)
A conductive laminate was produced in the same manner as in Example 1 except that the undercoat layer and the overcoat layer were not provided. Corona treatment was performed as the substrate surface treatment. This treatment increased the hydrophilicity of the substrate surface and lowered the water contact angle to 50-60 °.

(Comparative Example 2)
A conductive laminate was produced in the same manner as in Comparative Example 1 except that the back surface of the substrate was not provided with a hard coat layer (“Tough Top” THS manufactured by Toray Film Processing Co., Ltd.).

(Comparative Example 3)
A conductive laminate was produced in the same manner as in Example 1 except that no overcoat layer was provided.

(Comparative Example 4)
A conductive laminate was produced in the same manner as in Example 1 except that the material used for the overcoat layer was changed to urethane acrylate resin (“UF-8001G” manufactured by Kyoeisha Chemical Co., Ltd.). The pencil hardness of the overcoat layer was 6B. A conductive laminate was produced in the same manner as in Example 1 except that no overcoat layer was provided.

  It describes in Tables 1-3 about a layer structure, a surface resistance value evaluation result, and a haze evaluation result.

  The conductive laminate of the present invention excellent in transparent conductivity is preferably used as, for example, a display-related electrode such as a touch panel, a touch switch, a liquid crystal display, organic electroluminescence, and electronic paper, and an electrode for a transparent sheet heating element. Can do.

1: Base material 2: Undercoat layer 3: Layer containing carbon nanotubes 4: Overcoat layer 5: Conductive layer

Claims (9)

A conductive laminate having a conductive layer containing carbon nanotubes on at least one surface of a substrate, the conductive laminate satisfying the following (1) and (2).
(1) Surface resistance value when [A] is the surface resistance value before the high temperature humidification test (85 ° C., 85% relative humidity, 500 hours) and [B] is the surface resistance value after the high temperature humidification test is performed. The ratio [B] / [A] is 1.40 or less.
(2) Haze difference [D] − [H] before the high temperature humidification test (85 ° C., relative humidity 85%, 500 hours) is [C] and haze after the high temperature humidification test is [D]. C] is 0.1 or more and 5.0 or less.   Difference in haze [F] − when the haze before the high-temperature humidification test (85 ° C., relative humidity 85%, 500 hours) of the substrate is [E] and the haze after the high-temperature humidification test is [F]. The conductive laminate according to claim 1, wherein [E] is 0.1 or more and 5.0 or less.   The conductive laminate according to claim 1, further comprising an undercoat layer between the substrate and the conductive layer.   The conductive laminate according to claim 3, wherein the undercoat layer has a pencil hardness of H to 9H.   The conductive laminate according to claim 1, further comprising an overcoat layer on the conductive layer.   The conductive laminate according to claim 5, wherein the overcoat layer has a pencil hardness of H to 9H.   The conductive laminate according to claim 5, wherein the overcoat layer contains an acrylic resin.   The conductive laminate according to claim 1, wherein the glass transition point of the substrate is 85 ° C. or higher.   The conductive laminate according to claim 1, wherein the base material contains a polycarbonate resin.

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