JP2017065964A - Dispersion liquid containing carbon nanotube and conductive laminate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersion liquid containing carbon nanotube, which can give conductive anisotropy and increase conductivity with transparency, when a conductive laminate is formed therefrom.SOLUTION: The dispersion liquid contains carbon nanotube (CNT), in which the CNT has an aspect ratio of 1,300 or more; and the dispersion liquid containing CNT has a viscosity of 2.0 mPa s or more at a shear speed of 1,000/s. The dispersion liquid containing CNT contains a dispersant having a weight average molecular weight measured by gel permeation chromatography of 10000 to 400000, by 50 to 500 parts by mass with respect to 100 parts by mass of CNT, and contains an aqueous solvent. The dispersant is preferably an anionic dispersant, and more particularly, the dispersant preferably comprises carboxymethyl cellulose or its salt (Na salt, NHsalt, or the like) as a main component.SELECTED DRAWING: None

Description

  The present invention relates to a dispersion containing carbon nanotubes and a conductive laminate using the same. More specifically, the present invention relates to a dispersion liquid containing carbon nanotubes that provides a conductive laminate excellent in transparent conductivity.

  A carbon nanotube (hereinafter sometimes abbreviated as CNT) is a substance having a structure in which a graphite sheet having a hexagonal network of carbon atoms arranged is wound in a cylindrical shape. What is wound around is called multi-walled carbon nanotube. Among multi-walled carbon nanotubes, those wound in two layers are called double-walled carbon nanotubes.

  As known carbon nanotube production methods, synthesis by a laser ablation method, a chemical vapor deposition method (CVD (chemical vapor deposition) method), or the like is known. Among these, the CVD method is a synthesis method capable of controlling the reaction conditions such as the type of carbon raw material, the raw material supply rate, the synthesis temperature, the catalyst density and the like, and can synthesize carbon nanotubes in a relatively simple manner. Recently, it has become possible to selectively synthesize carbon nanotubes having a desired diameter, length, and number of layers. In the chemical vapor deposition method, the number of carbon nanotubes is controlled to be single or 2-5. It is known that it can be manufactured.

  Carbon nanotubes themselves have excellent conductivity and are expected to be used as conductive materials. In general, as carbon nanotubes, single-walled carbon nanotubes and double-walled carbon nanotubes with a small number of layers are known to have particularly high characteristics such as conductivity because they have a high graphite structure.

  Taking advantage of such characteristics, carbon nanotubes are used for transparent conductive laminates and the like. Moreover, the said transparent conductive laminated body can be preferably used as base materials with transparent conductive films, such as a touch panel, a liquid crystal display, organic electroluminescence, and electronic paper. In these applications, a transparent conductive laminate having higher conductivity is required.

  A conductive laminate using CNTs is produced by uniformly dispersing CNTs in a dispersion and coating them. These carbon nanotube dispersions are required to exhibit high conductivity when made into a transparent conductive laminate.

  For example, Patent Document 1 describes a method for producing a conductive laminate by applying a carbon nanotube dispersion liquid on various films to obtain a conductive laminate.

Japanese translation of PCT publication No. 2004-526838

  However, in the technique described in Patent Document 1, the conductive anisotropy is small, an efficient conductive network cannot be obtained, and a conductive laminate having high transparent conductivity cannot be obtained. In addition, when trying to impart high transparent conductivity, it may be possible to use a dispersion liquid containing metal nanowires other than carbon nanotubes, but the haze when formed into a film increases, the color reproducibility is poor, etc. A problem occurs.

  The present invention has been made in view of the above-mentioned problems and situations, and its problem is to provide a conductive anisotropy when a conductive laminate is produced, and to increase the transparent conductivity. It is to provide a dispersion.

The present invention provides a dispersion containing the following carbon nanotubes.
A carbon nanotube characterized in that the carbon nanotube has an aspect ratio of 1,300 or more and a viscosity at a shear rate of 1,000 / s of 2.0 mPa · s or more. Dispersion containing.

  According to the present invention, it is possible to provide a dispersion liquid including bonnanotubes which can have a conductive anisotropy and a high transparent conductivity when a conductive laminate is produced.

It is the schematic explaining the cutting-out method of the sample at the time of measuring Rmax / Rmin in this invention. It is the schematic explaining the synthesis | combining method of the carbon nanotube in this invention. It is a section schematic diagram explaining a touch panel which is an example of a display object in the present invention.

  A carbon nanotube characterized in that the carbon nanotube has an aspect ratio of 1,300 or more and a viscosity at a shear rate of 1,000 / s of 2.0 mPa · s or more. Dispersion containing.

  The dispersion containing carbon nanotubes of the present invention can exhibit high conductivity when coated on a substrate to form a conductive laminate.

[Carbon nanotube (CNT)]
(1) Kind of CNT The CNT 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. One surface of graphite is formed into one layer. Either a single-walled CNT wound or a multi-layered CNT wound in multiple layers can be applied. Among them, a CNT in which 50 or more of 100 double-layered CNTs in which one surface of graphite is wound in two layers is included. It is preferable because the conductivity and the dispersibility of CNTs in the dispersion liquid for coating become extremely high. More preferably, 75 or more of 100 are double-walled CNTs, and most preferably 80 or more of 100 are double-walled CNTs. It should be noted that the fact that 50 double-walled CNTs are contained in 100 may indicate that the ratio of double-walled CNTs is 50%. In addition, even when the surface of the two-walled CNT is functionalized by acid treatment or the like, it is preferable from the viewpoint that the original functions such as conductivity are hardly impaired.

(2) Manufacturing method of CNT CNT is manufactured as follows, for example. 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 CNT mixture containing single-layer to five-layer CNTs can be obtained by making the CNTs contact with each other at 200 ° C. to oxidize the CNTs. CNTs 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 CNT. Dopants are those that give surplus electrons to CNTs or take away electrons to form holes, and improve the conductivity of CNTs by generating carriers that can move freely. is there. The conditions for the nitric acid treatment are not particularly limited as long as the CNTs 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.

(3) CNT dispersant In the present invention, as the CNT dispersant, a surfactant, various dispersants (water-soluble dispersant, etc.) and the like can be used, but it is preferable to include an ionic dispersant having high dispersibility. . Examples of the ionic dispersant include an anionic dispersant, a cationic dispersant, and an amphoteric dispersant. Any type can be used as long as it has a high CNT dispersibility and can maintain dispersibility, but an anionic dispersant is preferred because of its excellent dispersibility and dispersion retention. Of these, carboxymethylcellulose and its salts (sodium salt, ammonium salt, etc.) and polystyrenesulfonic acid salt are preferable because CNT can be efficiently dispersed in the CNT dispersion. In particular, it is preferable that the ionic dispersant contains carboxymethyl cellulose as a main component. Here, the main component means occupying 60% by mass or more when the entire ionic dispersant is 100% by mass.

  In the present invention, when carboxymethyl cellulose salt or polystyrene sulfonate is used, examples of the cationic substance constituting the salt include alkali metal cations such as lithium, sodium and potassium, and alkaline earth such as calcium, magnesium and barium. Metal cation, ammonium ion, or monoamineamine, diethanolamine, triethanolamine, morpholine, ethylamine, butylamine, coconut oil amine, tallow amine, ethylenediamine, hexamethylenediamine, diethylenetriamine, polyethyleneimine and other onium ions, Alternatively, these polyethylene oxide adducts can be used, but are not limited thereto.

  The method for preparing the CNT dispersion is performed by surface modification of CNT used as a raw material and / or selection of a CNT dispersant.

  The method of the CNT surface modification treatment for adjusting the CNT dispersion is not particularly limited, but carboxyl groups, hydroxyl groups can be obtained by physical treatment such as corona treatment, plasma treatment and flame treatment, and chemical treatment such as acid treatment and alkali treatment. It is preferable to introduce an anionic group such as a group into the CNT side wall.

  As the CNT dispersant for adjusting the CNT dispersion liquid, any type can be used as long as it has high CNT dispersion ability and can maintain dispersibility. Among these, as the dispersant, the anionic dispersant described above is most preferable. When an anionic dispersant is used, if the pH of the CNT dispersion is 5.5 to 11, it may be an acidic functional group such as a carboxylic acid that modifies the CNT surface, or a dispersant located around the CNT. The ionization degree of acidic functional groups such as carboxylic acid contained is improved, and as a result, the CNT or the dispersant around the CNT has a negative potential. From the above, as a method for preparing the CNT dispersion, it is most preferable to select an anionic ionic dispersant in order to utilize electrostatic repulsion.

  Moreover, not only an anionic dispersing agent but a cationic dispersing agent and an amphoteric dispersing agent can also be used by combining the surface modification of CNT shown in the preceding clause.

  In the present invention, in order to use electrostatic interaction between the undercoat layer and the CNT, the anionic CNT present in the CNT dispersion is more cationic than the CNT dispersion. It is considered that a highly dispersed state was realized by electrostatic attraction and attracted to the surface of the film. Therefore, similarly, the cationic CNT present in the CNT dispersion is attracted to the surface of the undercoat layer having an anionic property compared to the CNT dispersion, and a high dispersion state is realized by electrostatic adsorption. Is also possible.

  The weight average molecular weight of the dispersant measured by gel permeation chromatography is preferably 10,000 to 400,000. This is because when the weight average molecular weight is 10,000 to 400,000, the interaction with CNTs is more effectively produced and the dispersion of CNTs becomes better. Although it depends on the length of the CNT, it is preferable that the weight average molecular weight is larger because the dispersant interacts with the CNT and the dispersibility is improved. For example, in the case of a polymer, when the polymer chain becomes long, the polymer is entangled with the CNT, and very stable dispersion is possible. However, if the weight average molecular weight is too large, the dispersibility may be lowered. Therefore, the weight average molecular weight is preferably 10,000 to 400,000, more preferably 10,000 to 200,000. The most preferred range of weight average molecular weight is 10,000 to 100,000.

  Moreover, it is preferable that dispersing agent content is 50 to 500 mass parts with respect to 100 mass parts of carbon nanotubes. Increasing the dispersant content above 500 parts by mass improves the dispersibility of CNTs, but when applied to a substrate to form a conductive laminate, the conductivity remains reduced because the dispersant remains between the contacts of the CNT network. There is a case.

  Therefore, the dispersant content is preferably 50 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the carbon nanotubes. More preferably, it is 50 to 300 mass parts, More preferably, it is 60 to 150 mass parts.

(4) CNT dispersion pH
The pH of the CNT dispersion can be adjusted by adding an acidic substance or a basic substance according to the definition of Arrhenius to the CNT dispersion. Acidic substances include, for example, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, borohydrofluoric acid, hydrofluoric acid, perchloric acid, organic carboxylic acids, phenols, organic sulfonic acids, etc. Is mentioned. Furthermore, examples of the organic carboxylic acid include formic acid, acetic acid, succinic acid, benzoic acid, phthalic acid, maleic acid, fumaric acid, malonic acid, tartaric acid, citric acid, lactic acid, succinic acid, monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid. Trifluoroacetic acid, nitroacetic acid, triphenylacetic acid and the like. Examples of the organic sulfonic acid include alkylbenzene sulfonic acid, alkyl naphthalene sulfonic acid, alkyl naphthalene disulfonic acid, naphthalene sulfonic acid formalin polycondensate, melamine sulfonic acid formalin polycondensate, naphthalene disulfonic acid, naphthalene trisulfonic acid, dinaphthylmethane. Examples include disulfonic acid, anthraquinone sulfonic acid, anthraquinone disulfonic acid, anthracene sulfonic acid, and pyrene sulfonic acid. Among these, preferred are volatile acids that volatilize during coating and drying, such as hydrochloric acid and nitric acid.

  Examples of the basic substance include sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia and the like. Among these, preferred is a volatile base that volatilizes during coating and drying, such as ammonia.

  The pH of the CNT dispersion is adjusted by adding the acidic substance and / or basic substance to a desired pH while measuring the pH. Examples of the pH measurement method include a method using a pH test paper such as litmus test paper, a hydrogen electrode method, a quinhydrone electrode method, an antimony electrode method, a glass electrode method, etc. Among them, the glass electrode method is simple and requires the required accuracy. Is preferable. In addition, when an excessive amount of an acidic substance or basic substance is added to exceed a desired pH value, a substance having the opposite characteristics may be added to adjust the pH. Nitric acid is preferable as an acidic substance applied for such adjustment, and ammonia is preferable as a basic substance.

(5) CNT dispersion The dispersion containing the carbon nanotubes of the present invention preferably contains the above-described dispersant and aqueous solvent. Here, the aqueous solvent is soluble in water or water and alcohols such as methanol, ethanol, isopropyl alcohol and butanol, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol, diethylene glycol and propylene glycol. Is an organic solvent mixed in an arbitrary ratio.

  The aqueous solvent used in the present invention is particularly preferably water from the viewpoint of easy treatment of the waste liquid.

  Although the preparation method of the CNT dispersion liquid used in this invention is not specifically limited, For example, it can carry out in the following procedures. Since the processing time at the time of dispersion can be shortened, once a dispersion liquid containing CNTs in a dispersion medium in a concentration range of 0.003 to 0.15 mass% is prepared, it is diluted to a predetermined concentration. It is preferable. In the present invention, the mass ratio of the dispersion medium to CNT (that is, the mass of the dispersion medium when the mass of CNT is 1) is preferably 10 or less. Within such a preferable range, it is easy to uniformly disperse, but there is little influence of the decrease in conductivity. The mass ratio of the dispersion medium to CNT is more preferably 0.5 to 9, further preferably 1 to 6, and particularly preferably 1 to 2.

  As a dispersion means at the time of preparation of the CNT dispersion liquid, a CNT and a dispersant are mixed and dispersed in a dispersion medium, which is commonly used for coating liquid production (for example, ball mill, bead mill, sand mill, jet mill, roll mill, homogenizer, ultrasonic homogenizer, high pressure) A homogenizer, an ultrasonic device, an attritor, a resolver, a paint shaker, etc.). Moreover, you may disperse | distribute in steps, combining these some mixing dispersers. Among them, the method of preliminarily dispersing with a vibration ball mill and then dispersing using an ultrasonic device is preferable because the dispersibility of CNT in the obtained coating dispersion liquid is good. Further, it is particularly preferable from the viewpoint of dispersibility of CNTs in a dispersion for coating which can be dispersed by a jet mill and a large amount of treatment at a time.

(6) Aspect ratio of CNT The aspect ratio of the CNT used in the present invention is preferably 1,300 or more. The aspect ratio is a value obtained by dividing the length of the CNT by the diameter, and is preferably 1,300 or more because the conductive anisotropy is easily developed. More preferably, it is 1,500 or more, More preferably, it is 2,000 or more.

  The diameter of the carbon nanotube is not particularly limited, but is preferably 1 nm to 10 nm, and particularly preferably within the range of 1 to 3 nm.

  The length of the carbon nanotube is preferably 1.5 μm or more because the conductive path cannot be efficiently formed if it is too short, and the upper limit is preferably 6 μm or less because the dispersibility tends to be lowered if it is too long. preferable.

  The length of the carbon nanotube can be examined using an atomic force microscope as described later. In the case of a CNT dispersion, several μL is dropped on a mica substrate and air-dried, and then examined with an atomic force microscope.

  The length of the carbon nanotubes in the conductive laminate can be observed in the same manner as in the case of the CNT dispersion before the CNT dispersion before coating. The concentration of the CNT dispersion to be dropped is preferably a concentration at which carbon nanotubes can be observed one by one, and may be appropriately diluted. For example, the concentration is 0.003% by mass.

  Regarding the length of the carbon nanotubes, a sample was prepared by the above method and observed with an atomic force microscope, and a photo was taken where 10 or more carbon nanotubes were contained in a 30 μm square field of view. Measure. The length of 100 carbon nanotubes arbitrarily extracted from the visual field is measured along the length direction. When 100 lines cannot be measured in one field of view, measurement is performed from a plurality of fields until 100 lines are obtained. By measuring the length of a total of 100 carbon nanotubes, the length and number of carbon nanotubes contained in the 100 can be confirmed. When the length of the carbon nanotube is long and the entire length is not visible in the field of view, the length of the carbon nanotube in the field of view is measured. If the length is within 10 μm, it is regarded as the length of the measured value. The number of carbon nanotubes in the range of 0.5 to 10 μm is counted as a length exceeding 10 μm.

[Viscosity of CNT dispersion]
The dispersion containing the carbon nanotubes of the present invention preferably has a viscosity of 2.0 mPa · s or more at a shear rate of 1,000 / s. By setting the viscosity to 2.0 mPa / s or more, when the CNT dispersion liquid is applied onto the substrate, the shearing force on the CNTs increases, and the orientation of the CNTs in the coating direction occurs. After the process, the orientation of the CNTs can be dried and fixed without returning to the original, and when the dispersion containing the carbon nanotubes of the present invention is coated on a substrate to form a conductive laminate, the conductive anisotropy is exhibited. Can be granted.

  The viscosity of the dispersion containing carbon nanotubes in the present invention at a shear rate of 1,000 / s is preferably 2.0 mPa · s or more, more preferably 4.0 mPa · s or more, and even more preferably 10.0 mPa · s or more. .

  In order to adjust the viscosity of the dispersion containing carbon nanotubes, for example, there are means such as adjusting the concentration of the dispersion, and adjusting the molecular weight of the dispersant when a dispersant is used. By increasing the concentration of the dispersion, the viscosity of the dispersion can be increased. Also, the viscosity of the dispersion can be increased by increasing the molecular weight of the dispersant.

[Conductive anisotropy]
When the dispersion containing the carbon nanotubes of the present invention is coated on a substrate to form a conductive laminate, a reference line is drawn in an arbitrary direction on the conductive laminate, and the measurement direction is set with respect to the reference line, Twelve 30 mm square samples of 0 °, 30 °, 60 °, 90 °, 120 °, and 150 ° are cut into two pieces for each measurement direction, and the resistance R between terminals in the measurement direction for each sample R ( When kΩ) is measured, the ratio (Rmax / Rmin) between the maximum value Rmax and the minimum value Rmin of the inter-terminal resistance value R is preferably 1.40 or more. Here, Rmax / Rmin being 1.40 or more indicates that there is anisotropy in conductivity in the conductive laminate, and the larger Rmax / Rmin, the more different the conductivity in the conductive laminate. It shows that the direction is larger. Rmax / Rmin is more preferably 1.80 or more. More preferably, it is 2.00 or more. When Rmax / Rmin is 1.40 or more, for example, even a conductive laminate having a surface resistance of 120 Ω / □ exhibits conductivity equivalent to 100 Ω / □ when a film is used in the direction of Rmin. When Rmax / Rmin is 1.80 or more, for example, a conductive laminate having a surface resistance value of 140 Ω / □ exhibits conductivity equivalent to 100 Ω / □ when a film is used in the direction of Rmin. When Rmax / Rmin is 2.00 or more, for example, even a conductive laminate having a surface resistance value of 150Ω / □ exhibits conductivity equivalent to 100Ω / □ if a film is used in the direction of Rmin. Therefore, when the conductive laminate is substantially used, the conductivity is increased, and the transparency is not changed depending on the orientation of the film to be used, so that the conductivity is increased. The resistance measurement between terminals is performed in order to know the volume resistance value of the conductive laminate. Although the volume resistance value can be measured even with a measuring machine equipped with a four-terminal method or an eddy current method, it is preferable to measure the resistance value between terminals in order to know the volume resistance value with respect to a certain potential direction.

[Transparent conductivity]
When the dispersion containing the carbon nanotubes of the present invention is coated on a substrate to form a conductive laminate, the light absorption rate and the surface resistance value may satisfy any of the following (a) to (h): preferable.
(A) The surface resistance value at a light absorption rate of 1% or more and less than 2% is 500Ω / □ or more and 2,000Ω / □ or less. (B) The surface resistance value at a light absorption rate of 2% or more and less than 3% is 200Ω / □. Above, 1,500Ω / □ or less (c) Surface resistance value at 3% or more and less than 4% is 100Ω / □ or more and 500Ω / □ or less (d) Surface at 4% or more and less than 5% light absorption rate Resistance value is 80Ω / □ or more and 400Ω / □ or less. (E) Light resistance is 5Ω or more and less than 7%. Surface resistance value is 60Ω / □ or more and 300Ω / □ or less. (F) Light absorption is 7% or more, 9 The surface resistance value at 50% / □ or more and 200Ω / □ or less (g) is less than 9%, and the surface resistance value at less than 11% is 40Ω / □ or more and 150Ω / □ or less (h) the light absorption rate is 11 %, The surface resistance value at less than 20% is 30Ω / □ or more, 00Ω / □ or less It should be noted that typical examples of an indicator of transparency, a light absorptance, the light absorptance of a conductive layer one layer inclusive conductive laminate is practical sense.

  Further, a typical index of conductivity is the surface resistance value of the conductive laminate, and the surface resistance value of the conductive laminate including one conductive layer has a practical meaning.

More preferably, the light absorption rate and the surface resistance value satisfy any of the following (a1) to (h1).
(A1) The surface resistance value at a light absorption rate of 1% or more and less than 2% is 500Ω / □ or more and 1,500Ω / □ or less. (B1) The surface resistance value at a light absorption rate of 2% or more and less than 3% is 200Ω / □. Above, 1,200Ω / □ or less (c1) Surface resistance value at 3% or more and less than 4% is 100Ω / □ or more and 450Ω / □ or less (d1) Surface at 4% or more and less than 5% Resistance value is 80Ω / □ or more and 350Ω / □ or less (e1) Light absorption rate is 5% or more and less than 7%, surface resistance value is 60Ω / □ or more, 250Ω / □ or less (f1) Light absorption rate is 7% or more, 9 The surface resistance value at 50% / □ or more and 150Ω / □ or less (g1) is less than 9%, and the surface resistance value at less than 11% is 40Ω / □ or more and 120Ω / □ or less (h1). % Or more and less than 20% surface resistance value 30Ω / □ or more and 80Ω / □ or less More preferably, the light absorption rate and the surface resistance value satisfy any of the following (a2) to (h2).
(A2) The surface resistance value at a light absorption rate of 1% or more and less than 2% is 500Ω / □ or more and 1,200Ω / □ or less. (B2) The surface resistance value at a light absorption rate of 2% or more and less than 3% is 200Ω / □. Above, 1,000Ω / □ or less (c2) Surface resistance value at 3% or more and less than 4% is 100Ω / □ or more and 400Ω / □ or less (d2) Surface at 4% or more and less than 5% Resistance value is 80Ω / □ or more and 300Ω / □ or less (e2) Light resistance is 5% or more and less than 7%, surface resistance value is 60Ω / □ or more, 200Ω / □ or less (f2) Light absorption is 7% or more, 9 The surface resistance value at 50% / □ or more and 130Ω / □ or less (g2) is less than 9%, and the surface resistance value at less than 11% is 40Ω / □ or more and 100Ω / □ or less (h2). % Or more and less than 20% surface resistance value 30Ω / □ or more and 70Ω / □ or less.

[Base material]
Resin, glass, etc. can be mentioned as a raw material of the base material used for this invention. Examples of the resin include polyethylene terephthalate (hereinafter abbreviated as PET), polyester such as polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide, polyphenylene sulfide, aramid, polypropylene, polyethylene, polylactic acid. Polyvinyl chloride, polymethyl methacrylate, alicyclic acrylic resin, cycloolefin resin, triacetyl cellulose, and the like can be used. As the glass, soda glass, white plate glass, non-alkali glass, or the like can be used. Moreover, these several base materials can also be used in combination. For example, a composite base material such as a base material in which a resin and glass are combined and a base material in which two or more kinds of resins are laminated may be used. The resin film may be provided with a hard coat. The kind of base material is not limited to the base material, and an optimal one can be selected from durability, cost, etc. according to the application. Although the thickness of a base material is not specifically limited, When using for display-related electrodes, such as a touch panel, a liquid crystal display, organic electroluminescence, and electronic paper, it is preferable to exist in the range of 10 micrometers-1,000 micrometers.

[Undercoat layer]
In the conductive laminate of the present invention, an undercoat layer is preferably provided on the substrate. The undercoat layer preferably contains an organic binder. Details of the undercoat layer will be described below.

(1) Wetting tension, thickness and roughness of undercoat layer The undercoat layer preferably has a wetting tension of 76 mN / m or more and 105 mN / m or less as defined in ISO8296 (2003). It is preferable that the wetting tension is 76 mN / m or more, because when the CNT dispersion liquid is applied on the undercoat layer, the application repellence hardly occurs and the CNT dispersion liquid can be applied uniformly. If the wetting tension of the undercoat layer is 105 mN / m or less, uneven coating due to spreading of the coating liquid during coating and uneven coating due to the influence of wind during drying are less likely to occur, and the CNT dispersion liquid is uniform. It is preferable because it can be applied to the surface. From the viewpoint of uneven coating, the wetting tension is preferably 76 mN / m or more and 105 mN / m or less, and more preferably 76 mN / m or more and 90 mN / m or less.

  The wetting tension of the undercoat layer can be increased by increasing the copolymerization amount of the hydrophilic functional group contained in the organic binder in the coating composition forming the undercoat layer or by increasing the thickness of the undercoat layer. Can be bigger. Therefore, the wetting tension of the undercoat layer can be appropriately adjusted depending on the copolymerization amount of the hydrophilic functional group contained in the organic binder, the type of the hydrophilic functional group, and the thickness of the undercoat layer.

  The thickness of the undercoat layer is not particularly limited as long as it is a range in which a phenomenon such as curling is unlikely to occur when the conductive laminate is formed. The wettability of the surface of the undercoat layer is preferably within the range of the preferred wetting tension, and the thickness varies depending on the type of organic binder, the type of functional group, the content of functional group, and the amount of particles to be added. . Therefore, it is preferably in the range of 8 nm to 3 μm. A thickness that can effectively obtain an antireflection effect due to optical interference is preferable because the light transmittance is improved. For this reason, it is more preferable that the thickness combined with the thickness of the overcoat layer described later is in the range of 20 nm to 600 nm. Furthermore, from the viewpoint of humidity resistance dependency, which will be described later, when the thickness is increased, the effect of incorporating the ionic dispersant into the undercoat layer is increased.

  The center coat average roughness SRa of the undercoat layer is preferably 2 nm to 15 nm. When SRa is 2 nm or more, the unevenness of the surface of the undercoat layer becomes large, and when the CNT dispersion containing the ionic dispersant is applied, the ionic dispersant can be easily taken into the undercoat layer, and ions from the conductive layer This is preferable because the removal of the ionic dispersant is effectively performed. Further, it is preferable to set SRa to 15 nm or less because the optical characteristics of the conductive laminate can be improved. If it exceeds 15 nm, light scattering at the interface with the conductive layer and the overcoat layer increases, and haze may increase. Therefore, in the present invention, the SRa of the undercoat layer is preferably 2 nm or more and 15 nm or less, and more preferably 5 nm or more and 15 nm or less.

  SRa of the undercoat layer in the present invention can be measured using a three-dimensional surface roughness measuring machine.

(2) Organic binder It is preferable that the undercoat layer contains a binder because the ionic dispersant can be more adsorbed to the undercoat layer. Examples of the binder include an organic binder and an inorganic binder, and an organic binder is more preferable from the viewpoint that the ionic dispersant can be more adsorbed and the undercoat layer is difficult to crack during patterning.

  The organic binder contained in the undercoat layer is an organic compound having a covalent bond and having a minimum unit of molecules composed of two or more types of atoms. As the composition of the organic compound, for example, phenol, silicon, nylon, polyethylene, polyester, olefin, vinyl, acrylic, cellulose and the like are preferable.

  The organic binder is preferably an organic binder having a hydrophilic functional group from the viewpoint of applicability to a substrate. The organic binder is more preferably a polyester resin having a hydrophilic functional group and / or an acrylic resin having a hydrophilic functional group from the viewpoint of applicability to a substrate. That is, the organic binder may be either a polyester resin having a hydrophilic functional group or an acrylic resin having a hydrophilic functional group, or a polyester resin having a hydrophilic functional group and an acrylic resin having a hydrophilic functional group. Both may be used.

  The polyester resin having a hydrophilic functional group refers to a polyester resin having a hydrophilic functional group at the terminal or side chain of the polyester resin in order to increase the hydrophilicity of the polyester resin and dissolve or disperse it in an aqueous solvent. Examples of hydrophilic functional groups include sulfonate groups and carboxylate groups. In order to make the polyester resin contain a hydrophilic functional group, a dicarboxylic acid having a sulfonate group, a diol and an ester-forming derivative thereof (a compound containing a sulfonate group), or a polyvalent carboxyl having three or more carboxylate groups. It can be obtained by using an acid and an ester-forming derivative thereof (a compound containing a trivalent or higher polyvalent carboxylic acid group) as a raw material for polyester.

  Examples of the compound containing a sulfonate group include alkali metal salts, alkaline earth metal salts, and ammonium salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 5-sodium sulfoisophthalic acid, and 4-sulfoisophthalic acid. However, it is not limited to these.

  Examples of the compound containing a trivalent or higher polyvalent carboxylate group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, and trimesin. Examples thereof include alkali metal salts such as acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid, alkaline earth metal salts, and ammonium salts. It is not limited to.

  As the carboxylic acid component constituting the polyester, aromatic, aliphatic, and alicyclic dicarboxylic acids and trivalent or higher polyvalent carboxylic acids can be used. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 5-sodium sulfoisophthalic acid, 1,4-naphthalenedicarboxylic acid, and ester-forming derivatives thereof. Can be used.

  Moreover, it is preferable that the said organic binder is an acrylic resin which has a hydrophilic functional group from a viewpoint of the applicability | paintability to a base material. As the acrylic resin having a hydrophilic functional group, any acrylic resin having a repeating structural unit derived from an acrylic monomer having a hydrophilic functional group may be used, but the repeating structural unit does not have a hydrophilic group. What consists of a repeating structural unit derived from an acryl-type monomer is preferable. It is preferable to use an acrylic resin having such a hydrophilic functional group because it is excellent in transparency and can hardly be repelled when a CNT dispersion is applied.

  An acrylic monomer having a hydrophilic functional group includes a hydrophilic group that is a polar atomic group having a strong interaction with water, that is, a cationic group that dissociates as a cation in water, and an anionic property that dissociates as an anion. And known acrylic monomers having a nonionic group that does not dissociate.

  Examples of the acrylic monomer having a cationic group include dimethylaminoethyl (meth) acrylate and salts thereof, ethyl trimethylammonium chloride (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropyl. Examples of acrylic monomers having an anionic group such as trimethylammonium chloride include (meth) acrylic acid and salts thereof, (meth) acrylic acid-2-sulfoethyl and salts thereof, and hydroxyethyl (meth). Examples of acrylic monomers having acryloyl phosphate and salts thereof and having nonionic groups include hydroxyalkyl (meth) acrylate, polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and the like. BeHere, “(meth) acryl” means “acryl” and / or “methacryl”.

  Examples of the acrylic monomer having no hydrophilic functional group include, for example, alkyl (meth) acrylate (C1-C8 linear and branched) esters, (meth) acrylate cyclohexyl, ( Examples include glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl acrylate, (meth) acrylonitrile, and the like.

  A compound containing a sulfonate group that is a hydrophilic functional group or a trivalent or higher polyvalent carboxylate group is 1 to 100 mol% when the total raw material component of the polyester constituting the polyester containing the hydrophilic functional group is 100 mol%. It is preferably 25 mol%. It is only possible to impart hydrophilicity to a polyester containing a hydrophilic functional group by making the compound containing a sulfonic acid group that is a hydrophilic functional group or a trivalent or higher polyvalent carboxylic acid base 1 mol% or more. It is preferable because it can be dissolved or dispersed in an aqueous solvent. A polyester containing a hydrophilic functional group can be stably produced by copolymerization by setting the compound containing a sulfonate group that is an aqueous functional group or a trivalent or higher polyvalent carboxylate group to 25 mol% or less. This is preferable because it is possible.

  As the glycol component of polyester, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, etc. should be used. Can do.

  The polyester resin having a hydrophilic functional group can be produced, for example, as follows. For example, a process for producing a polycarboxylic acid component after a first step of esterification or transesterification of a compound containing a dicarboxylic acid component and a glycol component, a sulfonate group or a trivalent or higher polyvalent carboxylate group After the first step of esterifying or transesterifying the dicarboxylic acid component and the glycol component, a compound containing a sulfonate group or a trivalent or higher polyvalent carboxylate group is added to produce a first step reaction. It can manufacture by the method of manufacturing by the process of the 2nd step made to polycondensate with a product. At this time, as the reaction catalyst, for example, alkali metal, alkaline earth metal, manganese, cobalt, zinc, antimony, germanium, titanium compound, or the like can be used.

  The polyester resin having a hydrophilic functional group obtained by the above production method is preferably dispersed or dissolved in a solvent to form a coating composition. Examples of means for dispersing or dissolving in an aqueous solvent include a method in which a polyester resin is dissolved or dispersed in an aqueous solution of an alkaline compound such as ammonia water, sodium hydroxide, potassium hydroxide, and various amines while stirring. In this case, a water-soluble organic solvent such as methanol, ethanol, isopropanol, butyl cellosolve, or ethyl cellosolve may be used in combination.

  The organic binder is more preferably both a polyester resin having a hydrophilic functional group and an acrylic resin having a hydrophilic functional group from the viewpoint of removing the ionic dispersant.

  Mass ratio (A / B) of content (hereinafter referred to as A) of polyester resin having hydrophilic functional group to content (hereinafter referred to as B) of acrylic resin having hydrophilic functional group contained in the undercoat layer ) Is preferably from 1/9 to 8/2. When (A / B) is less than 1/9, the entire undercoat layer becomes hard and may be easily broken. On the other hand, if (A / B) exceeds 8/2, the polyester resin itself having a hydrophilic functional group hardly cures, and the film may become too soft. Therefore, (A / B) is preferably 1/9 or more and 8/2 or less. More preferably, it is 2/8 or more and 5/5 or less. The content of the polyester resin having a hydrophilic functional group when the entire undercoat layer is 100% by mass is preferably 20% by mass or more and 50% by mass or less, and the content of the acrylic resin having a hydrophilic functional group is It is preferable that they are 50 to 80 mass%.

  The organic binder having a hydrophilic functional group obtained by the above production method may be uniformly dispersed by, for example, an emulsifier and in an emulsion state.

  The organic binder preferably contains a crosslinking agent. It is preferable to use an epoxy compound and / or an oxazoline compound as a crosslinking agent in order to strengthen the coating film of the undercoat layer and improve the heat and humidity resistance, the adhesion to the substrate, and the like. Only one of the epoxy compound or the oxazoline compound may be used, or both may be used together.

  As an epoxy compound, the compound containing an epoxy group in a molecule | numerator, its prepolymer, and hardened | cured material are mentioned, for example. Examples include condensates of epichlorohydrin with hydroxyl groups and amino groups such as ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, and polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, and the like. is there.

  Examples of the polyepoxy compound include sorbitol, polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylol. Examples of the propane polyglycidyl ether and diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether. Ether, polypropylene glycol diglycidyl ether, Ritetramethylene glycol diglycidyl ether and monoepoxy compounds include, for example, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds such as N, N, N ′, N ′,-tetraglycidyl-m. -Xylylenediamine, 1,3-bis (N, N-diglycidylamino) cyclohexane and the like.

  An oxazoline compound is a compound having an oxazoline group in the molecule. In particular, a polymer containing an oxazoline group is preferable, and it can be prepared by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer. Addition polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like can be mentioned, and one or a mixture of two or more thereof can be used. Among these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

  The other monomer is not limited as long as it is a monomer copolymerizable with an addition polymerizable oxazoline group-containing monomer. For example, alkyl (meth) acrylate (the alkyl group includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, (meth) acrylic acid esters such as n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group); acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene Unsaturated carboxylic acids such as sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); Unsaturated nitriles such as acrylonitrile, methacrylonitrile; (meth) acrylamide, N-alkyl ( (Meth) acrylamide, N, N-dialkyl (meth) acrylamide, As the alkyl group, unsaturated amides such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group and cyclohexyl group); vinyl acetate Vinyl esters such as vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α, β-unsaturated monomers such as vinyl chloride, vinylidene chloride and vinyl fluoride And α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and the like, and one or more of these monomers can be used.

  In this invention, the preparation amount of the crosslinking agent with respect to the binder is preferably 5 to 80 parts by mass, more preferably 10 to 30 parts by mass, and further preferably 10 to 20 parts by mass when the binder is 100 parts by mass. When the amount is less than 5 parts by mass, the undercoat layer may be brittle and may not sufficiently withstand moisture and heat. When the amount exceeds 80 parts by mass, the resin component containing a hydrophilic functional group is relatively reduced. In some cases, it may be difficult to apply the CNT dispersion, or the adhesion to the substrate may not be stable.

(3) Particles In the present invention, the undercoat layer preferably contains particles. By including particles, the surface roughness of the undercoat layer is increased, the incorporation of the ionic dispersant into the undercoat layer is effective, and the humidity resistance dependency is improved, which is preferable. Moreover, since antiblocking property can also be provided to an undercoat layer, it is preferable. That is, when the conductive laminate is produced by roll-to-roll, it may be necessary to wind up the substrate on which the undercoat layer is formed after the undercoat layer is formed. In that case, the undercoat layer may contain particles. The undercoat layer is preferred because it is difficult to block. Therefore, the content of the particles is preferably 15% by mass or more and 95% by mass or less when the entire undercoat layer is 100% by mass. If it is less than 15% by mass, unevenness on the surface of the undercoat layer may be insufficient, and the humidity resistance dependency may not be exhibited. On the other hand, if it exceeds 95% by mass, the particles may be excessive with respect to the binder, and the particles may fall off. Also, when the amount of particles exceeds 50% by mass, when the overcoat layer described later is applied, depending on the solvent of the overcoat layer, the surface of the undercoat is partially eroded and the particles that have come off fall off and aggregate to increase haze. As a more preferable range, it is 20 to 50% by mass. The range of 25 to 35% by mass is more preferable in terms of stably exhibiting humidity resistance dependency and stably suppressing haze rise.

  A preferable range of the particle diameter is 5 nm to 500 nm. When the thickness is less than 5 nm, it is difficult to uniformly disperse the particles, and conversely, the particles may aggregate to increase the apparent particle size in the undercoat layer. Moreover, when it exceeds 500 nm, a haze will raise and it may become cloudy white when a conductive laminated body is used for a display body. More preferably, they are 15 nm-100 nm, More preferably, they are 15 nm-40 nm. In addition, a particle diameter here means the average particle diameter measured by the dynamic light scattering method.

In the present invention, the particles have one purpose of imparting irregularities to the surface of the undercoat layer, and the particles used in the present invention may be organic particles, inorganic particles, or both. Absent. Examples of the composition of inorganic particles that can be used in the present invention include silica, colloidal silica, alumina, ceria, kaolin, talc, mica, calcium carbonate, barium sulfate, carbon black, zeolite, titanium oxide, and various metal oxides. Fine particles are preferred. In particular, inorganic colloidal particles are preferable from the viewpoint of dispersibility in a polyester resin having a hydrophilic functional group, hardness of the particles, heat resistance, and alkali resistance, and colloidal silica is particularly preferable. Furthermore, colloidal silica in which -SiOH groups and -OH ^- ions are present on the surface of colloidal silica, an electric double layer is formed in a negatively charged state, and is dispersed and stable in the solvent by electrostatic repulsion between colloidal silica. It is preferable that -SiOH groups and -OH colloidal silica surface ^- ion present, the electric double layer is formed at the charged state negatively, as the colloidal silicas dispersed stably in a solvent by the electrostatic repulsion between the colloidal silica, “Snowtex” (registered trademark) series manufactured by Nissan Chemical Industries, Ltd. and “Cataloid” series manufactured by JGC Catalysts & Chemicals Co., Ltd. are preferably used.

  As a composition of the organic particle which can be used for this invention, the particle | grains which use acrylic acid, styrene resin, thermosetting resin, silicone, an imide compound etc. as a structural component are mentioned, for example. Particles (so-called internal particles) that are precipitated by a catalyst or the like added during the polyester polymerization reaction are also preferably used. In particular, styrene / acrylic particles are preferable from the viewpoints of dispersibility in a polyester resin having a hydrophilic functional group and versatility. As the styrene / acrylic particles stably dispersed in the liquid, “Movinyl” (registered trademark) 972 manufactured by Nippon Synthetic Chemical Industry Co., Ltd. is preferably used.

(4) Method for forming undercoat layer The organic binder described above and, if necessary, a coating composition containing an additive and a solvent are applied onto a substrate, and the solvent is dried as necessary. An undercoat layer can be formed on the material.

  Moreover, it is preferable to use an aqueous solvent as a solvent for the coating composition. By using an aqueous solvent, rapid evaporation of the solvent in the drying step can be suppressed, and not only a uniform undercoat layer can be formed, but also the environmental load is excellent.

  Here, the aqueous solvent is soluble in water such as water or water and alcohols such as methanol, ethanol, isopropyl alcohol and butanol, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol, diethylene glycol and propylene glycol. A certain organic solvent is mixed in an arbitrary ratio.

  As a method for applying the coating composition onto the substrate, either an in-line coating method or an off-coating method can be used.

  The in-line coating method is a method of applying in the manufacturing process of the substrate. Specifically, it refers to a method of coating at any stage from melt extrusion of the thermoplastic resin constituting the substrate to heat treatment after biaxial stretching, and usually, after melt extrusion, it is rapidly cooled. The resulting substantially amorphous unstretched (unoriented) thermoplastic resin film (A film), followed by uniaxially stretched (uniaxially oriented) thermoplastic resin film (B film), or further width It is applied to any film of biaxially stretched (biaxially oriented) thermoplastic resin film (C film) before heat treatment.

  The off-coating method is a known wet coating method such as spray coating, dip coating, spin coating, knife coating, kiss coating, gravure coating, slot die coating, roll coating, bar coating, screen printing, inkjet printing, pad printing, Other types of printing can be used. 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. Moreover, application | coating may be performed in multiple times and it may combine two different types of application | coating methods. Preferred coating methods are gravure coating, bar coating, and slot die coating, which are wet coatings.

[Method for producing conductive laminate]
The manufacturing method of the electrically conductive laminated body which apply | coated the dispersion liquid containing the carbon nanotube of this invention on a base material is a manufacturing method of the electrically conductive laminated body which apply | coats the dispersion liquid containing a carbon nanotube and a carbon nanotube dispersing agent on a base material. Preferably, there is an undercoat layer (X) forming step for providing an undercoat layer (X) on a substrate, and a conductive liquid is provided on the undercoat layer (X) with a dispersion containing carbon nanotubes and a carbon nanotube dispersant. More preferably, it is a method for producing a conductive laminate having a conductive layer (Y) forming step for forming the layer (Y). Each step will be described below.

[Undercoat layer formation process]
As explained in the section of [Undercoat layer] described above, an organic binder and, if necessary, a coating composition containing an additive and a solvent are applied onto the substrate, and the solvent is dried as necessary. By this, an undercoat layer can be formed on the substrate. Here, as described above, the wetting tension of the undercoat layer is preferably 76 mN / m or more and 105 mN / m or less.

[Conductive layer forming step]
In the conductive laminate in which the dispersion containing the carbon nanotubes of the present invention is coated on the base material, the conductive layer includes a coating process in which the CNT dispersion liquid is applied on the undercoat layer, and a drying process in which the dispersion medium is subsequently removed. Formed through. Hereinafter, the conductive layer may be referred to as a CNT layer. In the coating step, when the CNT dispersion obtained by the above method is applied on the undercoat layer provided on the substrate, the CNT dispersant having a hydrophilic portion and surrounding the CNT is a hydrophilic undercoat. It is thought to be attracted to the surface of the layer. Further, the dispersion medium is then dried to fix the CNTs on the undercoat layer to form the CNT layer. However, the dispersion medium remains on the undercoat layer, and the CNT dispersant is transferred from the CNT layer to the undercoat layer. It is considered that the CNT dispersant is attracted to the surface of the undercoat layer having a hydrophilic group as in the case of the application while it is movable to the surface. Thus, it is considered that the CNT layer is well formed by attracting the dispersant to the undercoat layer. The phenomenon of attracting the CNT dispersant to the undercoat layer proceeds more preferably by using a hydrophilic undercoat layer having a wetting tension of 76 to 105 mN / m.

  In addition, in a conductive laminate produced by applying a CNT dispersion onto a substrate and drying it, the concentration of the dispersion during drying after application and electrostatic repulsion generated between the CNT dispersion and the substrate are increased. Due to the force, CNTs may be bundled. However, CNTs are negatively charged in the dispersion, and the CNT dispersion is applied onto the undercoat layer and dried, so that the CNT dispersed in the CNT dispersion is electrostatically adsorbed to the undercoat layer. It is preferable because the bundling of CNT that has occurred during drying on the substrate can be suppressed. Thereby, the conductive laminated body excellent in transparent conductivity can be obtained.

  In the conductive laminate of the present invention, the method for applying the CNT dispersion on the substrate is not particularly limited. Known application methods such as spray coating, dip coating, spin coating, knife coating, kiss coating, gravure coating, slot die coating, bar coating, roll coating, screen printing, inkjet printing, pad printing, other types of printing, etc. Available. Moreover, application | coating may be performed in multiple times and it may combine two different types of application | coating methods. The most preferred application methods are gravure coating, bar coating, and slot die coating.

The coating thickness at the time of applying the CNT dispersion on the substrate depends on the concentration of the CNT dispersion, and therefore may be appropriately adjusted so as to obtain a desired surface resistance value. The amount of CNT applied in the present invention can be easily adjusted in order to achieve various applications that require electrical conductivity. For example, coating weight if ^{0.1mg / m 2 ~5mg / m 2} , preferably possible to within a preferable range of light absorption rate after the protective layer formation shown below.

[Protective layer]
The conductive laminate in which the dispersion containing the carbon nanotubes of the present invention is coated on a substrate preferably has a protective layer (hereinafter referred to as an overcoat layer) on the conductive layer. In addition, it is preferable that an overcoat layer consists of a transparent film in order to improve transparency. It is preferable to have an overcoat layer because the transparent conductivity, heat resistance stability, and heat and humidity resistance can be further improved.

  As the material for the overcoat layer, both an organic material and an inorganic material can be used, but an inorganic material is preferable from the viewpoint of resistance value stability. Examples of the inorganic material include metal oxides such as silica, tin oxide, alumina, zirconia, and titania. Silica is preferable from the viewpoint of resistance value stability.

  In the conductive laminate of the present invention, the method for providing the overcoat layer on the conductive layer 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, Or other types of printing can be used. 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. Further, the operation of providing the overcoat layer on the conductive layer may be performed in a plurality of times, or two different methods may be combined. Preferred methods are gravure coating, bar coating, slot die coating, which are wet coatings.

  As a method for forming an overcoat layer containing silica using wet coating, an organic silane compound is preferably used. For example, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-iso-propoxysilane, tetra -Silica sol prepared by hydrolyzing an organosilane compound such as tetraalkoxysilane such as n-butoxysilane dissolved in a solvent is used as a coating solution, and the wet coating is performed. And a method of forming a silica thin film.

  The thickness of the overcoat layer is controlled by adjusting the silica sol concentration in the coating solution and the coating thickness at the time of coating. The thickness of the overcoat layer is more preferably 10 nm or more and 200 nm or less. When the thickness of the overcoat layer is less than 10 nm, the scattering of dopants such as nitric acid improving the conductivity of the CNTs cannot be suppressed, and the heat resistance may be lowered. If the thickness of the overcoat layer is greater than 200 nm, the difference in the amount of reflected light between where the CNT is present and where it is absent may be visible.

[Molding process]
When the dispersion containing the carbon nanotube of the present invention is coated on a substrate to form a conductive laminate, a molded body can be obtained using various molding methods. It can be formed by a forming method such as vacuum forming, compressed air forming, compressed air vacuum forming combining vacuum forming and compressed air forming, press forming, plug forming, laminate forming, in-mold forming, and insert forming. In the present invention, the properties of the resin used for the base material of the conductive laminate, the properties of the resin used for the layer laminated on the base material, and the thickness and the molding method are selected in accordance with the shape to be molded. However, film insert molding, vacuum molding, three-dimensional laminate molding, and hot press molding are preferably used from the viewpoint of productivity.

[Molded body]
The molded product as used in the present invention refers to a product obtained by molding the conductive laminate of the present invention by, for example, the method described in the above-mentioned section [Molding]. Moreover, the molded object of this invention can also be used by bonding with a decorative film and another resin material.

[Display]
The conductive laminate in which the dispersion containing the carbon nanotubes of the present invention is coated on a substrate can be preferably used by incorporating it into a display body, particularly a touch panel and electronic paper. Among them, a schematic cross-sectional view showing an example of a touch panel is shown in FIG. The touch panel incorporates the conductive laminate of the present invention in which a conductive layer having a network structure composed of a linear structure is laminated alone or in combination with another member, and as an example, a resistance film Examples include a touch panel and a capacitive touch panel. A touch panel on which the conductive laminate of the present invention is mounted is formed by joining and laminating a conductive laminate 301 with a bonding layer 304 such as an adhesive or an adhesive as shown in FIG. A hard coat layer 306 laminated on the screen side substrate 305 and the screen side substrate of the touch panel is provided. Such a touch panel is used, for example, by attaching a lead wire and a drive unit, etc., and incorporating it on the front surface of the liquid crystal display.

[Usage]
When the dispersion containing the carbon nanotubes of the present invention is coated on a base material to form a conductive laminate, or further processed into a molded body, in addition to a touch switch, a touch panel, a planar heating element, an electromagnetic wave Can be used for shields, antenna members, etc. Especially suitable for capacitive touch sensors, especially for home appliances and in-vehicle use, it is possible to improve the design, and because the haze of the molded product is low, the display quality is unlikely to be impaired and good electrostatic capacity can be obtained. It can be used as a capacitive touch sensor.

  Hereinafter, the manufacturing method of the dispersion liquid containing the carbon nanotube of this invention and the manufacturing method of a conductive laminated body are demonstrated concretely based on an Example. However, the present invention is not limited to the following examples.

<Various evaluation methods>
(1) Light Absorption Rate of Conductive Laminate A conductive laminate sampled at 5 cm × 10 cm was measured using an ultraviolet-visible infrared spectrophotometer UV-3150 manufactured by Shimadzu Corporation. Light is incident vertically from the side of the conductive laminate on which the conductive layer is formed, and the total light transmittance and relative reflectance at 550 nm are measured. Absorption rate was determined.
Light absorption rate (550 nm) = 100−total light transmittance (550 nm) −relative reflectance (550 nm).

(2) Surface resistance value of conductive laminate The probe was brought into close contact with the central portion on the conductive layer side of the conductive laminate sampled at 5 cm x 10 cm, and the resistance value was measured at room temperature by the four-terminal method. The used apparatus is a resistivity meter MCP-T360 manufactured by Dia Instruments, and the probe used is a 4-probe probe MCP-TPO3P manufactured by Dia Instruments.

(3) Inter-terminal resistance value A reference line is drawn on the conductive laminate in an arbitrary direction, and the measurement direction is 0 °, 30 °, 60 °, 90 °, 120 °, and 150 ° with respect to the reference line. Twelve 30 mm square samples are cut out as two pieces in each measurement direction, and the rotation outer side and rotation inner side of each sample (here, the rotation outer side and the rotation inner side are two sides perpendicular to the measurement direction in the cut out square) The conductive paste “ECM” (registered trademark) -100AF manufactured by Taiyo Ink Co., Ltd. was applied to the end 5 mm width of 80 μm in thickness, and dried by heating at 90 ° C. for 60 minutes. The conductive paste part was measured using a custom digital tester CDM-17D.

  The inter-terminal resistance value R is measured for each of the 12 samples, the maximum value of the measured inter-terminal resistance values R of the 12 samples is set as the maximum value Rmax, the minimum value is set as the minimum value Rmin, and the maximum value Rmax and the minimum value are measured. The ratio of Rmin (Rmax / Rmin) was calculated.

(4) Measurement of average diameter of CNT in CNT dispersion liquid using atomic force microscope 30 μL of carbon nanotube dispersion liquid whose carbon nanotube concentration is adjusted to 0.003% by mass is placed on a mica substrate and rotated at 3,000 rpm for 60 seconds. After spin coating, the diameter of 100 bundled or isolated carbon nanotubes was randomly measured with an atomic force microscope (SPM9600M, manufactured by Shimadzu Corporation), and the average diameter was calculated by arithmetic averaging.

(5) Measurement of average length of CNT in CNT dispersion liquid by atomic force microscope 30 μL of carbon nanotube dispersion liquid in which the concentration of carbon nanotubes is adjusted to 0.003 mass% is placed on a mica substrate, and the rotation speed is 3,000 rpm. After spin coating for 2 seconds, an atomic force microscope (manufactured by Shimadzu Corporation, SPM9600M) is regarded as an isolated carbon nanotube when the diameter of the carbon nanotube is equal to or less than the average diameter measured by the transmission electron microscope, The length of about 100 carbon nanotubes corresponding thereto was measured, and the average length was calculated by arithmetic averaging.

(6) Calculation of aspect ratio of CNT Calculate aspect ratio (average length of CNT / average diameter of CNT) from the average length of CNT calculated in (5) above and the average diameter of CNT calculated in (4). did.

(7) Measurement of Viscosity of CNT Dispersion Viscosity of CNT dispersion is measured according to JIS K7117-2 (1999), viscosity measurement method at a constant shear rate using a rotational viscometer-Appendix A coaxial-Double cylinder viscosity The measurement was performed according to the total. The measurement conditions are as follows.
Measuring instrument: Bohlin Gemini HR nano (Malvern)
Test temperature: 25 ° C
Shear rate: 1,000 / s.

(8) Weight average molecular weight of the 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.

<Base material>
The base materials used in each example and comparative example are shown below.

(1) Substrate A
・ Polyethylene terephthalate film ("Lumirror" (registered trademark) U48 manufactured by Toray Industries, Inc.)
・ Thickness 50 μm.

<Binder>
Each binder used in each example and comparative example is shown below.

(1) Organic binder (A)
An organic binder containing a polyester resin having a hydrophilic functional group and an acrylic resin having a hydrophilic functional group (A647-GEX manufactured by Takamatsu Yushi Co., Ltd., solid content concentration: 20% by mass, water solvent) in water and isopropanol (hereinafter, IPA) The ratio of water to IPA was 7: 3 by mass, and the solid content concentration of the resin was 5% by mass.

(2) Inorganic binder (B)
An inorganic binder containing ethyl silicate ("Colcoat" (registered trademark) N103X solid content concentration 2 mass%, IPA solvent) manufactured by Colcoat Co., Ltd., IPA solvent) was diluted with IPA so that the solid content concentration of the resin was 1 mass%. .

<Particle>
(1) Particle A
Particle size: 10 nm to 15 nm Colloidal silica (manufactured by Nissan Chemical Industries, Ltd. “Snowtex” (registered trademark) ST-O).

<CNT dispersion A>
The production method of the CNT dispersion used in each example and comparative example is shown below.

(1) Catalyst preparation example: catalyst metal salt support on magnesia 2.46 g of ammonium iron citrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 500 mL of methanol (manufactured by Kanto Chemical Co., Ltd.). To this solution, 100.0 g of magnesium oxide (MJ-30 manufactured by Iwatani Chemical Industry Co., Ltd.) was added, vigorously stirred for 60 minutes with a stirrer, and the suspension was concentrated to dryness at 40 ° C. under reduced pressure. The obtained powder was heated and dried at 120 ° C. to remove methanol, and a catalyst body in which a metal salt was supported on magnesium oxide powder was obtained. The obtained solid content was collected on a sieve with a particle size in the range of 20 to 32 mesh (0.5 to 0.85 mm) while being finely divided in a mortar. The iron content contained in the obtained catalyst body was 0.38% by mass. The bulk density was 0.61 g / mL. The above operation was repeated and subjected to the following experiment.

(2) CNT aggregate production example: synthesis of CNT aggregate CNT was synthesized using the apparatus shown in FIG. The reactor 203 is a cylindrical quartz tube having an inner diameter of 75 mm and a length of 1,100 mm. A quartz sintered plate 202 is provided at the center, a mixed gas introduction pipe 208 serving as an inert gas and source gas supply line is provided at the lower part of the quartz pipe, and a waste gas pipe 206 is provided at the upper part. Further, three electric furnaces 201 are provided as heaters surrounding the circumference of the reactor so that the reactor can be maintained at an arbitrary temperature. A thermocouple 205 is provided to detect the temperature in the reaction tube.

  The catalyst layer 204 was formed by taking 132 g of the solid catalyst body prepared in the catalyst preparation example and introducing the solid catalyst body onto the 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 using the mass flow controller 207 at 16.5 L / min. It was circulated through the layers. Thereafter, while supplying nitrogen gas, methane gas was further introduced at 0.78 L / min for 60 minutes using the mass flow controller 207, and the gas was passed through the catalyst body layer for reaction. The contact time (W / F) obtained by dividing the mass of the solid catalyst body by the flow rate of methane at this time was 169 minutes · g / L, and the linear velocity of the gas containing methane was 6.55 cm / second. The quartz reaction tube was cooled to room temperature while the introduction of methane gas was stopped and nitrogen gas was passed through at 16.5 L / min.

  The heating was stopped and the mixture was allowed to stand at room temperature, and after reaching room temperature, the CNT-containing composition containing the catalyst body and CNTs was taken out from the reactor.

(3) Purification of the CNT aggregate and oxidation treatment Using 130 g of the CNT-containing composition containing the catalyst body and CNT obtained in the CNT aggregate production example, the mixture is stirred in 4.8 mL of a 4.8N hydrochloric acid aqueous solution for 1 hour. As a result, iron as the catalyst metal and MgO as the carrier were dissolved. 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 3 times (de-MgO treatment). Thereafter, the CNT-containing composition was stored in a wet state containing water after washing with ion-exchanged water until the suspension of the filtered material became neutral. At this time, the mass of the entire wet CNT-containing composition containing water was 102.7 g (CNT-containing composition concentration: 3.12% by mass).

  About 300 times as much concentrated nitric acid (manufactured by Wako Pure Chemical Industries, Ltd., grade 1, Assay 60-61 mass%) was added to the dry mass of the obtained wet CNT-containing composition. Thereafter, the mixture was heated to reflux with stirring in an oil bath at about 140 ° C. for 25 hours. After heating to reflux, the nitric acid solution containing the CNT-containing composition was diluted with ion-exchanged water three times and suction filtered. After rinsing with ion-exchanged water until the suspension of the filtered material became neutral, a wet CNT aggregate containing water was obtained. At this time, the mass of the entire wet CNT composition containing water was 3.351 g (CNT-containing composition concentration: 5.29% by mass).

(4) Preparation of CNT dispersion liquid Wet CNT aggregate obtained above (15 mg in terms of dry weight) and 0.38 g of 10% by weight sodium carboxymethylcellulose (weight average molecular weight: 35,000) aqueous solution were weighed. Then, ion exchange water was added to make the total amount 10 g, and the pH was adjusted to 7 using a 28% aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.). This liquid was subjected to a dispersion treatment under ice-cooling using an ultrasonic homogenizer (VCX-130, manufactured by Iida Trading Co., Ltd.), with an output of 20 W for 1.5 minutes (2 kW · min / g). Thereafter, water was added to prepare a CNT dispersion liquid A so that the final concentration of the CNT aggregate was 0.06% by mass.

<CNT dispersion B>
In the CNT dispersion liquid prepared in the same manner as the preparation of (4) CNT dispersion liquid of the CNT dispersion liquid A, the CNT aggregate was prepared so that the concentration of the CNT aggregate was 0.03% by mass.

<CNT dispersion C>
In the CNT dispersion liquid prepared in the same manner as the preparation of (4) CNT dispersion liquid of CNT dispersion liquid A, the CNT aggregate was prepared so that the concentration of the CNT aggregate was 0.10% by mass.

<CNT dispersion D>
In the CNT dispersion liquid prepared in the same manner as in the preparation of (4) CNT dispersion liquid of the CNT dispersion liquid A, the CNT aggregate concentration was 0.15% by mass.

<CNT dispersion E>
In the CNT dispersion liquid prepared in the same manner as the preparation of the CNT dispersion liquid (4) of the CNT dispersion liquid A, the ultrasonic homogenizer was processed for 3 minutes.

<CNT dispersion F>
In the CNT dispersion liquid prepared in the same manner as the preparation of the CNT dispersion liquid (4) of the CNT dispersion liquid A, the ultrasonic homogenizer was processed for 7 minutes.

<CNT dispersion G>
In the CNT dispersion liquid prepared in the same manner as the preparation of (4) CNT dispersion liquid of CNT dispersion liquid A, the ultrasonic homogenizer was processed for 15 minutes.

<CNT dispersion H>
In the preparation of the CNT dispersion liquid (4) of the CNT dispersion liquid A, 15 mg of the wet CNT aggregate obtained above in terms of dry mass and 1% by mass sodium carboxymethylcellulose (Daicel Finechem Co., Ltd., Daicel) 1140) 1.5 g of aqueous solution was weighed, and ion exchange water was added to make 10 g. A 28% by mass aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.) was added to adjust the pH to 10, and then an ultrasonic homogenizer was used for dispersion treatment under ice-cooling at an output of 20 W for 1.5 minutes. During the dispersion treatment using an ultrasonic homogenizer, the temperature was controlled so that the liquid temperature was 1 to 20 ° C. The obtained treatment liquid was centrifuged at 10,000 G for 15 minutes in a high-speed centrifuge, and then ion-exchanged water was added to prepare a carbon nanotube aggregate concentration of 0.06% by mass. .

<CNT dispersion I>
In the CNT dispersion liquid produced in the same manner as the CNT dispersion liquid H, the CNT aggregate concentration was 0.15% by mass.

<CNT dispersion J>
A CNT dispersion containing carbon nanotubes (MWNT dispersion MW-I CNT aggregate concentration 2.0 mass%, water solvent, manufactured by Meijo Nanocarbon Co., Ltd.) is diluted with water, and the solid content concentration is 0.06 mass%. I tried to become.

(Examples 1-10, Comparative Examples 1-5)
One side of the substrate using a slit die coat (coating width 550 mm) equipped with an organic binder (A) with a combination of binder and particles shown in Table 1 and a shim (shim thickness 50 μm) made of stainless steel (sus) Was applied at a coating speed of 10 m / min and a flow rate of 33 cc / min, dried at 120 ° C. for 1 minute, and an undercoat layer was laminated. Moreover, when not providing an undercoat layer, the base-material surface was given the corona treatment on the conditions of E value 100W * s.

  Next, the CNT dispersion was undercoated at a coating speed of 10 m / min on one side of the substrate using a slit die coat (coating width 550 mm) equipped with a shim (shim thickness 50 μm) made of stainless steel (sus). A conductive component was formed on the layer by coating and drying at 120 ° C. for 1 minute. Furthermore, using a slit die coat (coating width 550 mm) in which the inorganic binder (B) is made of a material made of stainless steel (sus) with a thickness of 50 μm, the inorganic binder (B) is applied to the side where the conductive layer is laminated. Coating was performed at a work rate of 88 cc / min, and drying was performed at 125 ° C. for 1 minute to form a laminate.

  The evaluation results and the CNT dispersion used are listed in Tables 1 and 2.

  The conductive laminate of the present invention excellent in transparent conductivity can be preferably used as a display-related electrode such as a touch panel, a liquid crystal display, organic electroluminescence, and electronic paper. In addition, a molded body using a conductive laminate can be used for a sheet heating element, an electromagnetic wave shield, an antenna member, and the like in addition to a touch switch and a touch panel. Especially suitable for capacitive touch sensors, especially for home appliances and in-vehicle use, it is possible to improve the design, and because the haze of the molded product is low, the display quality is unlikely to be impaired and good electrostatic capacity can be obtained. It can be used as a capacitive touch sensor.

101: Terminal location for resistance measurement between terminals 201: Electric furnace 202: Sintered quartz plate 203: Reactor 204: Catalyst layer 205: Thermocouple 206: Waste gas pipe 207: Mass flow controller 208: Gas introduction pipe 301: On the touch panel Built-in conductive laminate 302: Base material of the conductive laminate incorporated in the touch panel 303: Conductive layer of the conductive laminate incorporated in the touch panel 304: Bonding layer 305 for laminating the conductive laminate using an adhesive or an adhesive Base material on the screen side of the touch panel 306: Hard coat layer laminated on the base material on the screen side of the touch panel

Claims (12)

A carbon nanotube characterized in that the carbon nanotube has an aspect ratio of 1,300 or more and a viscosity at a shear rate of 1,000 / s of 2.0 mPa · s or more. Dispersion containing. It contains 50 to 500 parts by mass of a dispersant having a weight average molecular weight of 10,000 to 400,000 and measured by gel permeation chromatography with respect to 100 parts by mass of carbon nanotubes, and an aqueous solvent. A dispersion containing the carbon nanotubes according to claim 1. The dispersion liquid containing carbon nanotubes according to claim 2, wherein the dispersant is an ionic dispersant. 4. The dispersion liquid containing carbon nanotubes according to claim 2, wherein the dispersant is carboxymethyl cellulose or a salt thereof. The dispersion containing carbon nanotubes according to claim 1, wherein the carbon nanotubes contain double-walled carbon nanotubes. A conductive laminate using the dispersion containing carbon nanotubes according to any one of claims 1 to 5, wherein a reference line is drawn on the conductive laminate in an arbitrary direction, and a measurement direction is set with respect to the reference line. , 0 °, 30 °, 60 °, 90 °, 120 °, 150 °, 30 mm square samples are cut into 12 pieces in each direction, and 12 pieces are cut out, and each sample has a resistance value R (kΩ between terminals) in the measurement direction. ), The ratio (Rmax / Rmin) between the maximum value Rmax and the minimum value Rmin between the samples is 1.40 or more. The conductive laminate according to claim 6, wherein the light absorption rate and the surface resistance value satisfy any of the following (a) to (h).
(A) The surface resistance value at a light absorption rate of 1% or more and less than 2% is 500Ω / □ or more and 2,000Ω / □ or less. (B) The surface resistance value at a light absorption rate of 2% or more and less than 3% is 200Ω / □. Above, 1,500Ω / □ or less (c) Surface resistance value at 3% or more and less than 4% is 100Ω / □ or more and 500Ω / □ or less (d) Surface at 4% or more and less than 5% light absorption rate Resistance value is 80Ω / □ or more and 400Ω / □ or less. (E) Light resistance is 5Ω or more and less than 7%. Surface resistance value is 60Ω / □ or more and 300Ω / □ or less. (F) Light absorption is 7% or more, 9 The surface resistance value at 50% / □ or more and 200Ω / □ or less (g) is less than 9%, and the surface resistance value at less than 11% is 40Ω / □ or more and 150Ω / □ or less (h) the light absorption rate is 11 %, The surface resistance value at less than 20% is 30Ω / □ or more, 00Ω / □ or less The conductive laminate according to claim 6, further comprising a protective layer on the conductive laminate. The conductive laminate according to claim 6, further comprising an undercoat layer on the substrate. The display body using the electrically conductive laminated body in any one of Claim 6 to 9. A molded body using the conductive laminate according to claim 6. A capacitive touch sensor using the conductive laminate according to claim 6 or the molded article according to claim 11.

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