JP2016055583A - Conductive laminate and touch panel using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive laminate having good adhesion to a conductive layer and small reflectance in a conductive laminate using a polyethylene terephthalate film as a substrate film and using a carbon nano tube as a conductive material.SOLUTION: There is provided a conductive laminate having a conductive layer composed of a carbon nanotube layer and an overcoat layer via an easy adhesion layer on a polyethylene terephthalate film having a refractive index (n1) of 1.61 to 1.70, where the easy adhesion layer has a refractive index (n2) of 1.61 to 1.70, the overcoat layer has a refractive index (n3) of 1.46 or lass and the conductive layer has a thickness of 80 to 120 nm.SELECTED DRAWING: None

Description

  The present invention relates to a conductive laminate having a conductive layer containing carbon nanotubes, and a touch panel using the same.

  In order to drive a touch panel mounted on a portable device, a tablet terminal, or the like, a conductive laminate (conductive film) is used.

  As a conductive material used for the conductive layer constituting the conductive laminate, metal oxides such as indium oxide doped with tin oxide (ITO) and antimony / tin oxide (ATO), metals such as silver and copper Conductive materials such as nanowires and carbon nanotubes are known.

  Development of a conductive laminate using carbon nanotubes as a conductive material is in progress. The conductive layer made of carbon nanotubes can be wet-coated, and can be manufactured by a simple process. Since carbon nanotubes are highly flexible, the conductive layer made of carbon nanotubes is provided on a flexible base film. There is an advantage that a conductive laminate having excellent flexibility can be obtained.

  Various plastic films are known as the base film constituting the conductive laminate. For example, polyethylene terephthalate film, triacetyl cellulose film, polycarbonate film, polyolefin film, polyamide film, acrylic film and the like are known.

  In the conductive laminate using carbon nanotubes, in order to increase the transmittance of the conductive laminate, it has been proposed to reduce the reflectance of the surface of the conductive laminate (Patent Documents 1 and 2). Patent Documents 1 and 2 disclose a polyethylene terephthalate film as a base film.

JP 2010-192186 A JP 2012-66580 A

  The polyethylene terephthalate film is excellent in dimensional stability, mechanical properties, electrical properties, chemical resistance, and the like, and is effective as a base film for a conductive laminate. On the other hand, since a polyethylene terephthalate film (especially a biaxially oriented polyethylene terephthalate film) is highly crystallized, there is a problem that it is difficult to obtain adhesion with a coating layer laminated on the polyethylene terephthalate film.

  Therefore, as one method for improving the adhesion between the polyethylene terephthalate film and the coating layer, it is known to provide an easy adhesion layer between the polyethylene terephthalate film and the coating layer. Conventionally known easy-adhesion layers are mainly made of polyester resin, acrylic resin or urethane resin as the resin, and the refractive index is about 1.48 to 1.54.

  In addition, since the polyethylene terephthalate film has a relatively high refractive index compared to other plastic films, the polyethylene terephthalate film itself tends to have a relatively high reflectance.

  On the other hand, when the conductive laminate is applied to the conductive film of the touch panel, if the reflectance of the surface of the conductive layer of the conductive laminate is high, a void layer (air layer) exists inside the touch panel. The interface reflection between the body surface (conductive layer surface) and the air layer is increased, which may cause a disadvantage that the touch panel transparency of light emission from an image display panel such as a liquid crystal is lowered.

  Therefore, an object of the present invention is to provide a conductive laminate in which a polyethylene terephthalate film is used as a base film and carbon nanotubes are used as a conductive material. The object is to provide a body and a touch panel using the body.

The above object of the present invention has been basically achieved by the following invention.
[1] On a polyethylene terephthalate film having a refractive index (n1) of 1.61 to 1.70, a conductive layer composed of a carbon nanotube layer and an overcoat layer is provided via an easy adhesion layer, and the easy adhesion layer The refractive index (n2) is 1.61-1.70, the refractive index (n3) of the overcoat layer is 1.46 or less, and the thickness of the conductive layer is 80-120 nm. Laminate.
[2] The conductive laminate according to [1], wherein the absolute value of the difference between the refractive index (n1) of the polyethylene terephthalate film and the refractive index (n2) of the easy-adhesion layer is 0.03 or less.
[3] The conductive laminate according to [1] or [2], wherein the easily adhesive layer has a thickness of 5 nm or more and less than 200 nm.
[4] A touch panel using the conductive laminate according to any one of [1] to [3].

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive laminated body with favorable adhesiveness of a conductive layer and a small reflectance and a touch panel using the same can be provided.

The conductive laminate according to the present invention is a conductive layer comprising a carbon nanotube layer and an overcoat layer on a polyethylene terephthalate film having a refractive index (n1) of 1.61 or more and 1.70 or less via an easy adhesion layer. The characteristic structure of the conductive laminate is as follows.
i) The refractive index (n2) of the easy adhesion layer is 1.61 or more and 1.70 or less,
ii) The refractive index (n3) of the overcoat layer is 1.46 or less,
iii) The thickness of the conductive layer is not less than 80 nm and not more than 120 nm.

  The conductive laminate of the present invention has an easy-adhesion layer and a conductive layer (a carbon nanotube layer and an overcoat layer having the above-mentioned characteristic structure) on a polyethylene terephthalate film having a refractive index (n1) of 1.61 to 1.70. In this case, the reflectance of the surface of the conductive layer can be effectively reduced.

  The reflectance (luminous reflectance) of the conductive layer surface in the conductive laminate of the present invention is preferably less than 1.5%, more preferably less than 1.4%, and further 1.3%. Is preferably less than 1.1%, particularly preferably less than 1.1%. The lower limit reflectance (luminous reflectance) is not particularly limited, but is practically about 0.1%.

  By using the conductive laminate with a reduced reflectance as described above for a touch panel (for example, a resistive touch panel), the space (air layer) and the surface of the conductive laminate (conductive layer surface) existing in the touch panel. As a result, a decrease in the amount of light emitted from a display panel such as a liquid crystal and transmitted through the touch panel is suppressed. That is, the amount of light transmitted through the touch panel can be relatively increased.

  Hereinafter, each component which comprises the electroconductive laminated body of this invention is demonstrated in detail.

[Polyethylene terephthalate film]
In the conductive laminate of the present invention, a polyethylene terephthalate film is used as a base film, and the refractive index (n1) of the polyethylene terephthalate film is 1.61 to 1.70.

  As the polyethylene terephthalate film, a biaxially stretched polyethylene terephthalate film (biaxially oriented polyethylene terephthalate film) is preferably used from the viewpoint of dimensional stability, mechanical properties, electrical properties, chemical resistance, and the like. The refractive index of the biaxially stretched polyethylene terephthalate film (biaxially oriented polyethylene terephthalate film) is usually in the range of 1.61-1.70.

  The refractive index (n1) of the polyethylene terephthalate film is preferably higher from the viewpoint of reducing the reflectivity of the conductive layer surface of the conductive laminate, specifically 1.62 or more, and preferably 1.63 or more. More preferably, 1.64 or more is particularly preferable.

  The upper limit of the refractive index (n1) of the polyethylene terephthalate film is preferably 1.69 or less, more preferably 1.68 or less, in relation to the refractive index of the easy-adhesion layer described later.

  The thickness of the polyethylene terephthalate film is suitably in the range of 20 to 300 μm, but is preferably 50 μm or more and more preferably 75 μm or more from the viewpoint of rigidity, strength, workability and the like. The upper limit thickness of the polyethylene terephthalate film is preferably 300 μm or less, more preferably 250 μm or less, and particularly preferably 200 μm or less from the viewpoint of securing a certain degree of flexibility and workability.

[Easily adhesive layer]
The easy adhesion layer used in the present invention is laminated directly on the polyethylene terephthalate film, and has a function of improving the adhesion between the conductive layer laminated on the easy adhesion layer and the polyethylene terephthalate film.

  It is important that the easy-adhesion layer used in the present invention has a refractive index (n2) of 1.61 to 1.70.

  The refractive index (n2) of the easy-adhesion layer is preferably higher from the viewpoint of reducing the reflectivity of the conductive layer surface of the conductive laminate, specifically 1.62 or more, and preferably 1.63 or more. More preferably, 1.64 or more is particularly preferable.

  On the other hand, if a relatively large amount of a high refractive index material described below is contained in order to increase the refractive index of the easy-adhesion layer, the adhesion improving function may not be sufficiently obtained. Accordingly, the upper limit of the refractive index (n2) of the easy adhesion layer is preferably 1.69 or less, and more preferably 1.68 or less, from the viewpoint of securing the function of the easy adhesion layer, ie, improvement in adhesion.

  From the viewpoint of reducing the reflectance of the conductive layer surface of the conductive laminate, the absolute value of the difference between the refractive index (n1) of the polyethylene terephthalate film and the refractive index (n2) of the easy-adhesion layer is 0.03. The following is preferable, and 0.02 or less is more preferable.

  The thickness of the easy-adhesion layer is not particularly limited, but from the viewpoint of coating properties and thickness accuracy in the lamination process of the easy-adhesion layer, slipperiness and blocking resistance of the easy-adhesion layer, or the appearance (color unevenness, etc.) of the conductive laminate. The thickness of the easy adhesion layer is preferably less than 200 nm, more preferably less than 100 nm, and particularly preferably less than 50 nm.

  The lower limit thickness of the easy adhesion layer is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 10 nm or more from the viewpoint of improving the adhesion between the polyethylene terephthalate film and the conductive layer.

  The easy adhesion layer preferably contains at least a resin from the viewpoint of improving the adhesion between the polyethylene terephthalate film and the conductive layer. As such a resin, it is preferable to use at least one resin selected from the group consisting of polyester resin, acrylic resin and urethane resin. The resin content in the easy-adhesion layer is preferably in the range of 20 to 90% by mass, more preferably in the range of 30 to 80% by mass, and more preferably in the range of 40 to 70% by mass with respect to 100% by mass of the total solid content of the easy-adhesion layer. A range is particularly preferred.

  The refractive index (n2) of the easy adhesion layer is 1.61-1.70, and the easy adhesion layer having a relatively high refractive index is, for example, a high refractive index such as a high refractive index resin or metal oxide particles. It can be obtained by including a material.

  Examples of the high refractive index resin include a resin having a high refractive index by introducing an aromatic ring, a sulfur atom, a bromine atom, or the like into a resin such as a polyester resin, an acrylic resin, or a urethane resin.

  As the high refractive index resin, a polyester resin having a condensed aromatic ring in the molecule is preferably used. The condensed aromatic ring is preferably a naphthalene ring or a fluorene ring.

  The polyester resin is generally obtained by polycondensation from a carboxylic acid component and a glycol component. The polyester resin having a naphthalene ring in the molecule can be synthesized by using a dicarboxylic acid having a naphthalene ring such as 1,4-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylic acid as a carboxylic acid component. The refractive index of the polyester resin having a naphthalene ring in the molecule can be controlled by adjusting the ratio of the dicarboxylic acid having a naphthalene ring in the total carboxylic acid component.

  The polyester resin having a fluorene ring in the molecule can be synthesized by using a compound having a fluorene ring as the carboxylic acid component and / or glycol component. The refractive index of the polyester resin can be controlled by adjusting the content of the compound having a fluorene ring. The polyester resin which has a fluorene ring in a molecule | numerator is described in detail in the international publication 2009/145075, for example, It can synthesize | combine with reference to it.

  Although content of high refractive index resin in an easily bonding layer is suitably adjusted according to the refractive index of an easily bonding layer, specifically, 10-80 mass with respect to 100 mass% of solid content total amount of an easily bonding layer. % Is preferable, a range of 20 to 70% by mass is more preferable, and a range of 30 to 60% by mass is particularly preferable.

  Examples of the metal oxide particles used to increase the refractive index of the easy adhesion layer include titanium oxide, zirconium oxide, zinc oxide, tin oxide, antimony oxide, cerium oxide, iron oxide, zinc antimonate, and tin oxide doped oxide. Examples include indium (ITO), antimony-doped tin oxide (ATO), phosphorus-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, and fluorine-doped tin oxide. These metal oxide particles may be used alone. A plurality may be used in combination. Among the metal oxide particles, titanium oxide and zirconium oxide are particularly preferable because they can increase the refractive index of the easy-adhesion layer without reducing transparency.

  Although content of the metal oxide particle in an easily bonding layer is suitably adjusted according to the refractive index of an easily bonding layer, specifically, 10-80 mass with respect to 100 mass% of solid content total amount of an easily bonding layer. % Is preferable, a range of 20 to 70% by mass is more preferable, and a range of 30 to 60% by mass is particularly preferable.

  When the easy adhesion layer contains metal oxide particles as a high refractive index material, it contains at least one resin selected from the group consisting of polyester resin, acrylic resin and urethane resin as described above. It is preferable. Further, it is more preferable to use the above-described high refractive index polyester resin as the resin.

  It is preferable for the easy adhesion layer to contain the metal oxide particles and the high refractive index polyester resin because the refractive index of the easy adhesion layer can be increased while suppressing the content of the metal oxide particles.

  When the easy-adhesion layer contains metal oxide particles, if the thickness of the easy-adhesion layer increases, the transparency of the easy-adhesion layer may decrease or cracks may occur in the easy-adhesion layer. The thickness of is preferably less than 50 nm, more preferably less than 40 nm, and particularly preferably less than 30 nm. The lower limit thickness is preferably 5 nm or more.

  The easy-adhesion layer preferably further contains a crosslinking agent. The easy adhesion layer is preferably a thermosetting layer containing a resin and a crosslinking agent. By making such an easily adhesive layer such a thermosetting layer, the adhesion between the polyethylene terephthalate film and the conductive layer can be further improved. The conditions (heating temperature, time) for thermosetting the easy-adhesion layer are not particularly limited, but the heating temperature is preferably 70 ° C or higher, more preferably 100 ° C or higher, particularly preferably 150 ° C or higher, and most preferably 200 ° C or higher. preferable. The upper limit is preferably 300 ° C. or lower. The heating time is preferably in the range of 5 to 300 seconds, and more preferably in the range of 10 to 200 seconds.

  Examples of the crosslinking agent contained in the easy adhesion layer include melamine crosslinking agents, oxazoline crosslinking agents, carbodiimide crosslinking agents, isocyanate crosslinking agents, aziridine crosslinking agents, and epoxy crosslinking agents. Among these, melamine-based crosslinking agents, oxazoline-based crosslinking agents, and carbodiimide-based crosslinking agents are preferably used.

  The content of the crosslinking agent in the easy-adhesion layer is preferably in the range of 1 to 40% by mass, more preferably in the range of 3 to 35% by mass, and more preferably in the range of 5 to 30% with respect to 100% by mass of the total solid content of the easy-adhesion layer. % Range is particularly preferred.

  The easy-adhesion layer preferably contains organic or inorganic particles in order to further improve slipperiness and blocking resistance. Examples of such particles include, but are not limited to, inorganic particles such as silica, calcium carbonate and zeolite particles, acrylic particles, silicone particles, polyimide particles, Teflon (registered trademark) particles, crosslinked polyester particles, crosslinked polystyrene particles, and crosslinked particles. Organic particles such as polymer particles and core-shell particles are exemplified. Among these particles, silica is preferable, and colloidal silica is more preferably used.

  The average particle diameter of the particles is preferably 30 nm or more, more preferably 50 nm or more, and particularly preferably 100 nm or more from the viewpoint of improving slipperiness and blocking resistance. The upper limit of the average particle diameter is preferably 500 nm or less, more preferably 400 nm or less, and particularly preferably 300 nm or less.

  The content of the particles in the easy adhesion layer is preferably in the range of 0.05 to 8% by mass, more preferably in the range of 0.1 to 5% by mass with respect to 100% by mass of the total solid content of the easy adhesion layer.

  The easy adhesion layer can be laminated on the polyethylene terephthalate film by a wet coating method. In particular, it is preferable to laminate the easily adhesive layer by a so-called “in-line coating method” in which the polyethylene terephthalate film is laminated in the production process.

  When applying an easy-adhesion layer on a polyethylene terephthalate film, as a pretreatment for improving the coating property and adhesion, the surface of the polyethylene terephthalate film may be subjected to corona discharge treatment, flame treatment, plasma treatment, etc. preferable.

  Examples of the wet coating method include a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method, a spin coating method, and an extrusion coating method.

  The above-described in-line coating method will be described below, but the present invention is not limited to this.

  After vacuum drying PET pellets with an intrinsic viscosity of 0.5 to 0.8 dl / g, which is a raw material for polyethylene terephthalate (PET) film, it is supplied to an extruder and melted at 260 to 300 ° C., and then in sheet form from a T-shaped die. And is wound around a mirror-casting drum having a surface temperature of 10 to 60 ° C. using an electrostatic application casting method, and is cooled and solidified to produce an unstretched PET film. This unstretched PET film is stretched 2.5 to 5 times in the longitudinal direction (referring to the traveling direction of the film and also referred to as “longitudinal direction”) between rolls heated to 70 to 100 ° C. The uniaxially stretched PET film obtained by this stretching is subjected to corona discharge treatment in the air, the wet tension of the surface is set to 47 mN / m or more, and the coating solution for forming an easy adhesion layer is applied to the treated surface by the above method. .

  Next, the uniaxially stretched PET film coated with the coating solution is gripped with a clip, guided to a drying zone, dried at a temperature lower than Tg of the uniaxially stretched PET film, then raised to a temperature equal to or higher than Tg, and again at a temperature near Tg. And then continuously stretched in the heating zone at 70 to 150 ° C. in the transverse direction (referred to as the direction perpendicular to the film traveling direction, also referred to as “width direction”) 2.5 to 5 times, and subsequently 180 to Heat treatment is performed in a heating zone at 240 ° C. for 5 to 40 seconds to obtain a laminated polyethylene terephthalate film in which an easy-adhesion layer is laminated on a PET film in which crystal orientation is completed. In addition, you may perform a 3-12% relaxation process as needed during the said heat processing. Biaxial stretching may be longitudinal, transverse sequential stretching, or simultaneous biaxial stretching, and may be re-stretched in either the longitudinal or transverse direction after longitudinal and transverse stretching.

[Conductive layer]
The conductive layer according to the present invention includes a carbon nanotube layer and an overcoat layer. That is, the conductive layer according to the present invention is preferably a layer using a carbon nanotube layer and an overcoat layer. The overcoat layer is formed by coating on the carbon nanotube layer. The overcoat layer serves to protect the carbon nanotube layer.

  The conductive layer according to the present invention comprises a carbon nanotube layer and an overcoat layer, the refractive index (n3) of the overcoat layer is 1.46 or less, and the thickness of the conductive layer is in the range of 80 to 120 nm. is important.

  The refractive index (n3) of the overcoat layer is preferably 1.44 or less, more preferably 1.42 or less, and more preferably 1.40 or less from the viewpoint of further reducing the reflectance of the conductive layer surface of the conductive laminate. Particularly preferred. The lower limit of the refractive index (n3) of the overcoat layer is not particularly limited, but is practically about 1.20.

  The thickness of the conductive layer composed of the carbon nanotube layer and the overcoat layer is preferably in the range of 85 to 115 nm, particularly in the range of 90 to 110 nm, from the viewpoint of further reducing the reflectance of the conductive layer surface of the conductive laminate. preferable.

[Carbon nanotube layer]
The carbon nanotube layer according to the present invention is a layer containing at least carbon nanotubes.

  The carbon nanotube is not particularly limited as long as it has a shape obtained by winding one surface of graphite into a cylindrical shape. Single-walled carbon nanotubes in which one surface of graphite is wound in one layer, wound in multiple layers. Multi-walled carbon nanotubes can be applied. Among these, double-walled carbon nanotubes in which one surface of graphite is wound in two layers are preferable because of high conductivity and dispersibility of the carbon nanotubes in the dispersion.

  A carbon nanotube having a diameter of about 0.3 to 100 nm and a length of about 0.1 to 20 μm is preferably used. In particular, from the viewpoint of increasing the transparency of the conductive layer and reducing the surface resistance, the carbon nanotubes preferably have a diameter of 1 to 10 nm and a length of 1 to 10 μm.

  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 manufactured 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, 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 to 50 hours.

  The carbon nanotube layer can be formed by applying a dispersion containing carbon nanotubes by a wet coating method. Examples of the wet coating method include cast coating, dip coating, spin coating, knife coating, kiss coating, roll coating, gravure coating, slot die coating, and bar coating. Of these, the slot die coating method is preferably used.

  The dispersion containing carbon nanotubes (carbon nanotube dispersion) preferably contains a carbon nanotube dispersant. As such a dispersant, an ionic dispersant having high dispersibility is preferably used. Examples of the ionic dispersant include an anionic dispersant, a cationic dispersant, and an amphoteric dispersant. Among these ionic dispersants, anionic dispersants are preferably used because of excellent dispersibility and dispersion retention of carbon nanotubes. Among the anionic dispersants, carboxymethyl cellulose and salts thereof (sodium salt, ammonium salt, etc.) and polystyrene sulfonic acid salt are preferable because carbon nanotubes can be efficiently dispersed.

  The content of the dispersant is preferably in the range of 50 to 1000 parts by mass with respect to 100 parts by mass of the carbon nanotubes from the viewpoint of ensuring good dispersibility without reducing the conductivity of the carbon nanotubes. The range of parts by mass is more preferable, and the range of 200 to 400 parts by mass is particularly preferable.

  The dispersion medium used for the preparation of the carbon nanotube dispersion liquid is preferably water from the viewpoints that the above-described dispersant can be safely dissolved and that the waste liquid can be easily treated.

  The carbon nanotube dispersion is, for example, a carbon nanotube and a dispersing agent mixed in a dispersion medium (for example, a ball mill, a bead mill, a sand mill, a roll mill, a homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, an ultrasonic device, an attritor, a resolver, It can be prepared by dispersing using a paint shaker or the like. These mixing and dispersing machines may be used alone or may be dispersed stepwise by combining a plurality of mixing and dispersing machines. Among them, a method of preliminarily dispersing with a vibrating ball mill and then dispersing using an ultrasonic device is preferable because the dispersibility of the carbon nanotubes is good.

  The concentration of the carbon nanotubes when dispersing the carbon nanotubes is preferably in the range of 0.003 to 0.15% by mass because the treatment time during dispersion can be shortened. The carbon nanotube dispersion prepared in this manner is further diluted and adjusted to a predetermined concentration suitable for coating.

  In applying the carbon nanotube dispersion liquid, alcohol or a surfactant can be contained in the carbon nanotube dispersion liquid in order to improve the coating property. Among these, alcohol is preferable, and lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and isopropyl alcohol are preferably used.

The carbon nanotube content in the carbon nanotube layer is appropriately set depending on the use of the conductive laminate, but in the case of the use of the touch panel, a range of 0.5 to 20 mg / m ² is appropriate, and 1 to 10 mg / m. A range of ² is preferred. Thereby, the surface resistance value of the conductive laminate can be set to 10 ⁴ Ω / □ or less.

Also, the total solid content coating amount of the carbon nanotube layer is suitably in the range of 2 to 50 mg / ^{m 2,} the range of 3 to 30 mg / ^{m 2} is preferred.

  The thickness of the carbon nanotube layer is preferably in the range of 1 to 20 nm, more preferably in the range of 2 to 15 nm, and particularly preferably in the range of 3 to 10 nm.

[Overcoat layer]
The overcoat layer is formed by coating on the carbon nanotube layer. The overcoat layer serves to protect the carbon nanotube layer.

  The refractive index (n3) of the overcoat layer is 1.46 or less, preferably 1.44 or less, more preferably 1.42 or less, and particularly preferably 1.40 or less. The lower limit refractive index is about 1.20.

  In order to set the refractive index of the overcoat layer to 1.46 or less, the overcoat layer is preferably formed of a material having a relatively low refractive index. Examples of the material having a relatively low refractive index include silicon compounds and fluorine compounds, and these compounds can be used alone or in combination of two or more.

  As a silicon compound, an alkoxysilane compound and its hydrolyzate, a polysiloxane compound, a silica particle etc. are mentioned, for example, These compounds can be used individually or in combination of 2 or more types.

  Examples of the alkoxysilane compound include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and methyltripropoxy. Silane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltri And propoxysilane.

  Examples of the alkoxysilane compound having a polymerizable functional group include vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane.

  As the polysiloxane compound, a compound having a molecular weight of 5000 or less is preferable, and a compound having a polymerizable functional group (ethylenically unsaturated group such as vinyl group or acrylic group) in the molecule is preferable. For example, a polysiloxane compound having an acrylic group at one or both ends of the molecule can be mentioned.

  As the silica particles, particles having an average particle size of 5 to 150 nm are preferable, particles having an average particle size of 8 to 100 nm are preferable, and particles having an average particle size of 10 to 70 nm are particularly preferable. Further, from the viewpoint of lowering the refractive index of the overcoat layer, silica particles having a cavity inside (hollow silica) are preferably used.

  Examples of the fluorine compound include fluorine-containing monomers, fluorine-containing oligomers, fluorine-containing polymer compounds, fluorine-containing silane compounds, and magnesium fluoride particles. These compounds can be used alone or in combination of two or more.

  Here, the fluorine-containing monomer and fluorine-containing oligomer are monomers and oligomers having an ethylenically unsaturated group such as a vinyl group or an acrylic group and a fluorine atom in the molecule.

  Examples of the fluorine-containing monomer and fluorine-containing oligomer include 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate, and 2- (perfluorobutyl). ) Ethyl (meth) acrylate, 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl (meth) acrylate, β- (per Fluoro-containing (meth) acrylic esters such as fluorooctyl) ethyl (meth) acrylate, di- (α-fluoroacrylic acid) -2,2,2-trifluoroethylethylene glycol, di- (α-fluoroacrylic acid) ) -2,2,3,3,3-pentafluoropropylethylene glycol, di (Α-fluoroacrylic acid) -2,2,3,3,4,4,4-hexafluorobutylethylene glycol, di- (α-fluoroacrylic acid) -2,2,3,3,4,4,4 5,5,5-nonafluoropentylethylene glycol, di- (α-fluoroacrylic acid) -2,2,3,3,4,4,5,5,6,6,6-undecafluorohexylethylene glycol , Di- (α-fluoroacrylic acid) -2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptylethylene glycol, di- (α-fluoro Acrylic acid) -2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctylethylene glycol, di- (α-fluoroacrylic acid) -3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8-tridecafluorooctylethylene glycol, di- (α-fluoroacrylic acid) -2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9 , 9-heptadecafluorononylethylene glycol and the like di- (α-fluoroacrylic acid) fluoroalkyl esters.

  Examples of the fluorine-containing polymer compound include a fluorine-containing copolymer having a fluorine-containing monomer and a monomer for imparting a crosslinkable group as constituent units. Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc. ), (Meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, and the like. As a monomer for imparting a crosslinkable group, in addition to a (meth) acrylate monomer having a crosslinkable functional group in the molecule like glycidyl methacrylate, it has a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. ) Acrylate monomers (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.).

  Examples of the fluorine-containing silane compound include trifluoromethylmethoxysilane, trifluoromethylethoxysilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, and tridecafluorooctyltrimethoxysilane. Heptadecafluorodecyltriethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecylmethyldimethoxysilane, and the like.

  As the magnesium fluoride particles, particles having an average particle diameter of 5 to 150 nm are preferable, particles having an average particle diameter of 8 to 100 nm are preferable, and particles having an average particle diameter of 10 to 70 nm are particularly preferable.

  The overcoat layer can contain an ultraviolet curable acrylic monomer in addition to the above-described silicon compound and / or fluorine compound. The ultraviolet curable acrylic monomer is not particularly limited, and examples thereof include methyl (meth) acrylate, lauryl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, and phenoxyethyl (meth) acrylate. Monofunctional acrylates such as tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxy (meth) acrylate, Neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythrito Rutri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, Multifunctional acrylates such as tripentaerythritol tri (meth) acrylate, tripentaerythritol hexa (meth) triacrylate, trimethylolpropane (meth) acrylic acid benzoate, trimethylolpropane benzoate, glycerin di (meth) acrylate hexa Urethane acrylates such as methylene diisocyanate, pentaerythritol tri (meth) acrylate hexamethylene diisocyanate, etc. It can be mentioned.

  In the present invention, from the viewpoint of obtaining an overcoat layer having a relatively low refractive index, the overcoat layer is preferably formed from the following thermosetting composition.

  Examples of such a thermosetting composition include a composition mainly composed of a siloxane polymer formed by bonding with silica particles. Specifically, such a composition is obtained by reacting and homogenizing the silica component of the silica particles and the siloxane polymer of the matrix, and the siloxane polymer bonded to the silica particles is present in the presence of the silica particles. A polyfunctional silane compound can be obtained by forming a silanol compound once by a known hydrolysis reaction in a solvent with an acid catalyst and utilizing a known condensation reaction.

  As said silica particle, the silica particle (hollow silica) which has a colloidal silica and a cavity inside is preferable, The average particle diameter has the preferable range of 5-150 nm, Furthermore, the range of 8-100 nm is preferable, Especially 10-70 nm. The range of is preferable.

  A commercial item can be used for colloidal silica. For example, “Snowtex” and “organosilica sol” of Nissan Chemical Industries, Ltd. and “CATAROID” of JGC Catalysts & Chemicals Co., Ltd. can be mentioned.

  The silica particle having a cavity inside is a silica particle having a cavity part surrounded by an outer shell. The volume occupied by the cavities in the silica particles having cavities therein, that is, the porosity of the particles is preferably 5% or more, more preferably 10% or more, and even more preferably 30% or more. The upper limit porosity is preferably 70% or less. Such silica particles having cavities are described in, for example, the method described in paragraphs [0033] to [0046] of JP-A-2001-233611 and paragraph [0043] of Japanese Patent No. 3272111. Can be manufactured by the following methods. Moreover, what is generally marketed can also be used.

  As said polyfunctional silane compound, the above-mentioned alkoxysilane compound and fluorine-containing silane compound are mentioned.

  The thermosetting composition preferably further contains a curing agent. Examples of such a curing agent include titanium, zirconium, aluminum, and magnesium. Among these, from the viewpoint of relatively reducing the refractive index, an aluminum-based or magnesium-based curing agent having a low refractive index is preferable. These curing agents can be easily obtained by reacting a metal alkoxide with a chelating agent. Examples of chelating agents include β-diketones such as acetylacetone, benzoylacetone, and dibenzoylmethane; β-keto acid esters such as ethyl acetoacetate and ethyl benzoylacetate.

  Preferable specific examples of the metal group chelate compound include ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetate bis (ethyl acetoacetate), aluminum tris Aluminum chelate compounds such as (acetylacetonate), magnesium chelate compounds such as ethyl acetoacetate magnesium monoisopropylate, magnesium bis (ethylacetoacetate), alkyl acetoacetate magnesium monosopropylate, magnesium bis (acetylacetonate) It is done. Of these, aluminum tris (acetylacetonate), aluminum tris (ethyl acetoacetate), magnesium bis (acetylacetonate), and magnesium bis (ethyl acetoacetate) are preferable, considering storage stability and availability. Then, aluminum tris (acetylacetonate) and aluminum tris (ethylacetoacetate) are particularly preferable.

  The overcoat layer is formed by applying the coating solution comprising the above composition by the same coating method as the wet coating method used for coating the carbon nanotube layer, and drying and curing (curing by heat curing or ultraviolet irradiation). ).

  The thickness of the overcoat layer is adjusted so that the thickness of the conductive layer is in the range of 80 to 120 nm in consideration of the thickness of the carbon nanotube layer.

[Conductive laminate]
In the conductive laminate of the present invention, the easy adhesion layer and the conductive layer may be provided only on one side of the polyethylene terephthalate film, or the easy adhesion layer and the conductive layer may be provided on both sides of the polyethylene terephthalate film. .

  In the conductive laminate of the present invention, when an easy-adhesion layer and a conductive layer are provided only on one side of the polyethylene terephthalate film, a hard coat described later is provided on the side opposite to the conductive layer across the polyethylene terephthalate film. A layer can be provided.

  The conductive laminate of the present invention is suitable for an electrode substrate of a touch panel. In order to use suitably for a touch panel etc., the one where the surface resistance value of a conductive laminated body is low is preferable from the point of drive stability. Specifically, the surface resistance value of the conductive laminate is preferably 10,000Ω / □ or less, more preferably 5,000Ω / □ or less, and particularly preferably 2,000Ω / □ or less. The lower limit is about 1Ω / □.

  When the conductive laminate is used for touch panel applications, high adhesion may be required, but the conductive laminate of the present invention is preferable because it has high adhesion.

[Hard coat layer]
In the conductive laminate of the present invention, a hard coat layer can be provided on the surface opposite to the conductive layer with a polyethylene terephthalate film interposed therebetween. The hard coat layer is provided for imparting scratch resistance, antifouling property, fingerprint resistance and the like. Further, it is possible to impart antiglare properties 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 because of its excellent properties such as transparency and hardness when cured.

  The thickness of the hard coat layer is preferably in the range of 0.5 to 7 μm, more preferably in the range of 1 to 5 μm, from the viewpoint of imparting good scratch resistance to the conductive laminate and from the viewpoint of curling property.

  It is preferable that the surface of the polyethylene terephthalate film on which the hard coat layer is laminated has an easy adhesion layer. The refractive index of the easy adhesion layer is preferably 1.55 or more and less than 1.60.

  The refractive index of the hard coat layer is usually in the range of 1.48 to 1.54. In the present invention, the refractive index of the polyethylene terephthalate film (1.61 to 1.70) and the refractive index of the hard coat layer. Due to the large difference, interference fringes may occur on the hard coat layer surface side.

  Generation | occurrence | production of this interference fringe can be suppressed by making the refractive index of an easily bonding layer into 1.55 or more and less than 1.60. Furthermore, from the viewpoint of suppressing interference fringes, the refractive index of the easy adhesion layer is more preferably in the range of 1.56 to 1.59, and particularly preferably in the range of 1.57 to 1.59.

  The easy adhesion layer having such a refractive index range is to adjust the content of high refractive index resin (particularly high refractive index polyester resin) and metal oxide particles used in the easy adhesion layer provided on the conductive layer side. Obtained by.

  The thickness of the easy adhesion layer is preferably in the range of 60 to 130 nm, particularly preferably in the range of 70 to 120 nm, from the viewpoint of suppressing interference fringes.

[Method for producing conductive laminate]
The conductive laminate according to the present invention is preferably manufactured, for example, by the following manufacturing method. That means
When producing a conductive laminate having a conductive layer composed of a carbon nanotube layer and an overcoat layer with a thickness of 80 to 120 nm on a polyethylene terephthalate film via an easy adhesion layer, the refractive index (n1) is 1.61. A step of applying a coating composition having a refractive index (n2) of 1.61 to 1.70 on a polyethylene terephthalate film of ˜1.70 and laminating an easy adhesion layer, and carbon nanotubes on the easy adhesion layer A step of laminating a carbon nanotube layer by applying a dispersion containing a carbon nanotube, a step of laminating an overcoat layer by applying a coating composition having a refractive index (n3) of 1.46 or less on the carbon nanotube layer And a method for producing a conductive laminate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In addition, the measuring method and evaluation method in a present Example are shown below.

[Evaluation method]
(1) Measurement of refractive index A high-speed spectrometer M is applied to a coating film formed by applying each coating composition for forming each layer (easily adhesive layer, overcoat layer, hard coat layer) on a silicon wafer. -2000 (manufactured by JA Woollam) was used to measure the change in the polarization state of the reflected light of the coating film at an incident angle of 60 degrees, 65 degrees, and 70 degrees, and the refractive index at a wavelength of 550 nm was measured with the analysis software WVASE. Obtained by calculation.

  Moreover, the refractive index of the polyethylene terephthalate film measured the refractive index of 550 nm with the Abbe refractometer according to JISK7105 (1981).

(2) cutting out a section of the measurement the adhesive layer is a polyethylene terephthalate film laminated in the thickness of the adhesive layer to the ultra-thin sections, RuO ₄ staining, OsO ₄ staining, or by staining ultramicrotomy by double staining of both The cross-sectional structure is observed under the following conditions with a TEM (transmission electron microscope), and the thickness of the easy adhesion layer is measured from the cross-sectional photograph.
Measurement device: Transmission electron microscope (H-7100FA type, manufactured by Hitachi, Ltd.)
・ Measurement conditions: Acceleration voltage 100kV
-Sample preparation: frozen ultrathin section method-Magnification: 300,000 times.

(3) Measurement of the thickness of the conductive layer A sample (conductive laminate) in which a conductive layer composed of a carbon nanotube layer and an overcoat layer is laminated is cut into ultrathin sections and accelerated by a TEM (transmission electron microscope). Observation is performed at a voltage of 100 kV (observation at a magnification of 1 to 300,000 times), and the thickness is measured from the cross-sectional photograph. The thickness was measured at five locations, and the average value was taken as the thickness.

(4) Measurement of average particle diameter of particles in particle-containing layer A cross section of a sample (conductive laminate) on which a particle-containing layer is laminated is observed with a TEM (transmission electron microscope) at an acceleration voltage of 100 kV ( Observed at a magnification of 1 to 300,000 times), and from the cross-sectional photograph, the maximum length of each of 30 randomly selected particles was measured, and the value obtained by arithmetically averaging them was determined as the average particle diameter of the particles. did.

(5) Measurement of luminous reflectance <Sample preparation>
The surface of the conductive laminate opposite to the side provided with the conductive layer was roughened with sandpaper, and further painted with black ink to prepare a measurement sample.

<Measurement>
Using a spectrophotometer (“UV3150PC” manufactured by Shimadzu Corporation), the reflectance (single-sided reflection) at a wavelength of 380 to 780 nm was measured at an incident angle of 5 degrees from the measurement surface (surface of the conductive layer) of the measurement sample. , The reflection reflectance Y defined in the luminous reflectance (JIS Z8701-1999) of the C light source was determined. The spectral solid angle is measured with a spectrophotometer, and the reflectance (single-sided light reflection) is calculated according to JIS Z8701-1999. The calculation formula is as follows.
T = K · ∫S (λ) · y (λ) · R (λ) · dλ (however, the integration interval is 380 to 780 nm)
T: single-sided light reflectance S (λ): standard light distribution used for color display y (λ): color matching function R (λ) in XYZ display system: spectral solid angle reflectance.

(6) Adhesiveness of conductive layer After putting 100 crosscuts of 1 mm ^{2 on} the surface of the conductive layer of the conductive laminate, a cellophane tape manufactured by Nichiban Co., Ltd. was applied on it, and pressed strongly with a finger. The adhesiveness was evaluated according to the following criteria based on the number of pieces that peeled rapidly in the 90-degree direction and remained.
○: 90/100 (remaining number / measured number) or more x: less than 90/100 (remaining number / measured number).

[Coating composition for forming an easily adhesive layer]
(Coating composition a1)
100 parts by mass of the following naphthalene ring-containing polyester resin, 60 parts by mass of zirconium oxide, and 15 parts by mass of a melamine-based crosslinking agent (methylol-type melamine-based crosslinking agent (“Nicarak MW12LF” manufactured by Sanwa Chemical Co., Ltd.)) An aqueous dispersion containing 1 part by mass of colloidal silica having an average particle diameter of 190 nm. The refractive index of this coating composition was 1.65.

<Naphthalene ring-containing polyester resin>
A polyester resin having the following copolymer composition.
・ Carboxylic acid component terephthalic acid 35mol%
2,6-Naphthalenedicarboxylic acid 9 mol%
5-Na sulfoisophthalic acid 6 mol%
・ Glycol component ethylene glycol 49 mol%
Diethylene glycol 1 mol%.

(Coating composition a2)
100 parts by mass of the naphthalene ring-containing polyester resin, 45 parts by mass of zirconium oxide, and 15 parts by mass of a melamine-based crosslinking agent (methylol-type melamine-based crosslinking agent (“Nicarak MW12LF” manufactured by Sanwa Chemical Co., Ltd.)) An aqueous dispersion containing 1 part by mass of colloidal silica having an average particle diameter of 190 nm. The refractive index of this coating composition was 1.63.

(Coating composition a3)
100 parts by mass of the naphthalene ring-containing polyester resin, 90 parts by mass of zirconium oxide, and 15 parts by mass of a melamine-based cross-linking agent (methylol-type melamine-based cross-linking agent (“Nicarac MW12LF” manufactured by Sanwa Chemical Co., Ltd.)) An aqueous dispersion containing 1 part by mass of colloidal silica having an average particle diameter of 190 nm. The refractive index of this coating composition was 1.67.

(Coating composition a4)
100 parts by weight of the naphthalene ring-containing polyester resin, 15 parts by weight of a melamine-based cross-linking agent (methylol-type melamine-based cross-linking agent (“Nicarac MW12LF” manufactured by Sanwa Chemical Co., Ltd.)), and an average particle size of 190 nm It is an aqueous dispersion containing 1 part by mass of colloidal silica. The refractive index of this coating composition was 1.58.

(Coating composition a5)
100 parts by mass of the following acrylic resin, 15 parts by mass of melamine-based cross-linking agent (methylol-type melamine-based cross-linking agent (“Nicarac MW12LF” manufactured by Sanwa Chemical Co., Ltd.)), and 1 colloidal silica having an average particle diameter of 190 nm An aqueous dispersion containing parts by mass. The refractive index of this coating composition was 1.52.

<Acrylic resin>
An acrylic resin having the following copolymer composition.
・ Methyl methacrylate 63% by weight
Ethyl acrylate 35% by weight
Acrylic acid 1% by weight
N-methylolacrylamide 1% by weight.

[Coating composition for overcoat layer formation]
(Coating composition oc1)
109.0 parts by mass of methyltrimethoxysilane, 56.8 parts by mass of heptadecafluorodecyltrimethoxysilane, and 12 parts by mass of dimethyldimethoxysilane were dissolved in 300 parts by mass of diacetone alcohol and 100 parts by mass of isopropanol. In this solution, 56 parts by mass of colloidal silica (trade name MIBK-ST, manufactured by Nissan Chemical Industries, Ltd., solid content: 30% by mass) dispersed in methyl isobutyl ketone and 60 parts by mass of water and acetic acid are dispersed. 2 parts by mass were added dropwise with stirring so that the reaction temperature did not exceed 30 ° C. After the dropwise addition, the obtained solution was heated at a bath temperature of 40 ° C. for 2 hours, and then the solution was heated at a bath temperature of 85 ° C. for 2 hours, the internal temperature was raised to 80 ° C. and heated for 1.5 hours, The solution A was obtained.

  A solution obtained by dissolving 3.8 parts by mass of magnesium bis (ethylacetoacetate) in 250 parts by mass of methanol is added to the obtained solution A, and further 1700 parts by mass of isopropanol and 500 parts by mass of diacetone alcohol. Was added and stirred at room temperature for 2 hours to prepare a coating composition. The refractive index of this coating composition was 1.40.

(Coating composition oc2)
A coating composition was prepared in the same manner as the coating composition oc1 except that the amount of colloidal silica added was changed from 56 parts by mass to 250 parts by mass. The refractive index of this coating composition was 1.38.

(Coating composition oc3)
95.2 parts by mass of methyltrimethoxysilane and 65.4 parts by mass of trifluoropropyltrimethoxysilane were dissolved in 300 parts by mass of propylene glycol monomethyl ether and 100 parts by mass of isopropyl alcohol. In this solution, 297.9 parts by mass of silica fine particle dispersion liquid (isopropanol dispersion type, solid content concentration 20.5% by mass, manufactured by Catalyst Kasei Kogyo Co., Ltd.) having cavities inside with an average particle diameter of 50 nm, 54 parts by mass of water and 1.8 parts by mass of formic acid was added dropwise with stirring so that the reaction temperature did not exceed 30 ° C. After the dropwise addition, the obtained solution was heated at a bath temperature of 40 ° C. for 2 hours, and then the solution was heated at a bath temperature of 85 ° C. for 2 hours. The internal temperature was raised to 80 ° C. and heated for 1.5 hours. Until solution B was obtained.

  In the obtained solution B, 4.8 parts by mass of aluminum tris (acetyl acetate) (trade name: Aluminum Chelate A (W), manufactured by Kawaken Fine Chemical Co., Ltd.) is dissolved in 125 parts by mass of methanol as an aluminum curing agent. Then, 1500 parts by mass of isopropanol and 250 parts by mass of propylene glycol monomethyl ether were added, and the mixture was stirred at room temperature for 2 hours to prepare a coating composition. The refractive index of this coating composition was 1.36.

(Coating composition oc4)
In a container, 20 parts by mass of ethanol was added, and 40 parts by mass of n-butyl silicate was added and stirred for 30 minutes. Then, after adding 10 mass parts of 0.1N hydrochloric acid aqueous solution, it stirred for 2 hours (hydrolysis reaction) and stored at 4 degreeC. After 24 hours, this solution was prepared by diluting with isopropyl alcohol, toluene and n-butanol mixed solution (mixing mass ratio 2 to 1 to 1) so that the solid content concentration was 1.0% by mass. The refractive index of this coating composition was 1.44.

(Coating composition oc5)
100 parts by mass of triethylene glycol diacrylate (“Light Acrylate 3EG-A” manufactured by Kyoeisha Chemical Co., Ltd.), photopolymerization initiator (“Irgacure (registered trademark) 184” manufactured by Ciba Specialty Chemicals) 3 Mass parts were dissolved in an organic solvent (methyl isobutyl ketone) to prepare a coating composition having a solid content concentration of 1.0% by mass. The refractive index of this coating composition was 1.48.

(Coating composition oc6)
Forse Seed 420C (solid content concentration 50% by mass, acrylic resin) manufactured by China Paint Co., Ltd. was diluted with toluene to a solid content concentration of 1.0% by mass to prepare a coating composition. The refractive index of this coating composition was 1.50.

[Coating composition for forming hard coat layer]
58 parts by mass of dipentaerythritol hexaacrylate, urethane acrylate oligomer (“UN-901T” from Negami Kogyo Co., Ltd .; containing 9 ethylenically unsaturated groups in the molecule), polymerization initiator (Ciba Specialty) 5 parts by mass of “Irgacure (registered trademark) 184” manufactured by Chemicals Co., Ltd. was dispersed and dissolved in an organic solvent (methyl isobutyl ketone). The refractive index of this composition was 1.52.

[Coating composition for forming carbon nanotube layer]
(Catalyst preparation example: Catalytic metal salt supported on magnesia)
2.46 parts by mass of ammonium iron citrate (Wako Pure Chemical Industries, Ltd.) was dissolved in 400 parts by mass of methanol (Kanto Chemical Co., Ltd.). To this solution, 100 parts by mass of magnesium oxide (MJ-30 manufactured by Iwatani Chemical Industry Co., Ltd.) was added and vigorously stirred with a stirrer for 60 minutes to form a suspension. Concentrated to dryness at ° C. 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 was finely divided in a mortar, and a catalyst body having a particle size in the range of 20 to 32 mesh (0.5 to 0.85 mm) was collected using a sieve. The iron content contained in the obtained catalyst body was 0.38% by mass.

(Example of carbon nanotube aggregate production: synthesis of carbon nanotube aggregate)
A catalyst layer was formed by taking 132 parts by mass of the solid catalyst body prepared in the catalyst preparation example 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 using a mass flow controller and flows so as to pass through the catalyst layer. I let you. Thereafter, while supplying nitrogen gas, methane gas was further introduced using a mass flow controller, and the gas was passed through the catalyst layer to cause reaction. Next, 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.

  The heating was stopped and the mixture was allowed to stand at room temperature. After the temperature reached room temperature, a carbon nanotube-containing composition containing a catalyst body and carbon nanotubes (with an aspect ratio of 100 or more) was taken out from the reactor.

(Purification of carbon nanotube aggregate and oxidation treatment)
The catalyst metal obtained by the carbon nanotube aggregate production example and the carbon nanotube-containing composition containing carbon nanotubes are used as catalyst metals by stirring for 1 hour in 2160 parts by mass of a 4.8N hydrochloric acid aqueous solution using 130 parts by mass of the carbon nanotube-containing composition. Iron and its support MgO were dissolved. The resulting black suspension was filtered, and the filtered product was again put into 432 parts by mass 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 carbon nanotube-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 wet carbon nanotube-containing composition containing water was 102.7 parts by mass (carbon nanotube-containing composition concentration: 3.12% by mass).

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

(Preparation of carbon nanotube dispersion)
The obtained wet carbon nanotube aggregate (25 parts by mass in terms of dry mass), 6% by mass of sodium carboxymethylcellulose (cellogen 7A (weight average molecular weight: 190,000) manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1040 mass To a dispersion obtained by adding 6700 parts by mass of a zirconia bead (“Traceram” manufactured by Toray Industries, Inc., bead size: 0.8 mm) to a container, a 28% by mass aqueous ammonia solution (manufactured by Kishida Chemical Co., Ltd.) was added. The pH was adjusted to 10. The container was shaken for 2 hours using a vibrating ball mill to prepare a carbon nanotube paste.

  Next, this carbon nanotube paste is diluted with ion-exchanged water so that the concentration of carbon nanotubes is 0.15% by mass, and a 28% by mass aqueous ammonia solution is again added to 10 parts by mass of the diluted solution to adjust the pH to 10. It was adjusted. The aqueous solution was dispersed with an ultrasonic homogenizer under ice cooling. The liquid temperature during dispersion was adjusted to 10 ° C. or lower. The obtained liquid was centrifuged with a high-speed centrifuge for 15 minutes to obtain 9 parts by mass of a carbon nanotube dispersion.

(Preparation of carbon nanotube-containing coating composition)
Ion exchange water was added to the carbon nanotube dispersion to obtain a coating composition having a solid content adjusted to 0.04% by mass.

[Example 1]
A conductive laminate was produced in the following manner.

<Preparation of polyethylene terephthalate film (PET film) having an easy adhesion layer>
PET pellets (intrinsic viscosity 0.63 dl / g) substantially free of externally added particles are sufficiently vacuum-dried, then supplied to an extruder, melted at 285 ° C., extruded from a T-shaped die into a sheet shape, It was wound around a mirror-casting drum having a surface temperature of 25 ° C. using an electric application casting method and cooled and solidified. This unstretched film was heated to 90 ° C. and stretched 3.4 times in the longitudinal direction to obtain a uniaxially stretched film (uniaxially oriented film). After performing corona discharge treatment in air on both sides of this uniaxially stretched film, the coating composition a1 of the easy adhesion layer is easily applied to one surface (first surface) of the uniaxially stretched film, and the other surface (second surface). The coating composition a4 for the adhesive layer was applied.

  Next, the uniaxially stretched film coated with the respective easy-adhesion layer coating composition on both sides is held with a clip, guided to a preheating zone, dried at an ambient temperature of 75 ° C., raised to 110 ° C. using a radiation heater, and again 90 After drying at ℃, continuously stretched 3.5 times in the width direction in a heating zone at 120 ℃, followed by heat treatment for 20 seconds in the heating zone at 220 ℃, and biaxially oriented PET film in which crystal orientation is completed (Biaxially oriented PET film) was produced. This PET film is a PET film having an easy adhesion layer on both sides.

  The thickness of this PET film was 100 μm, and the thickness of the easy adhesion layer provided on the first surface and the second surface was 80 nm.

  The refractive index of the PET film was 1.65, the refractive index of the easy-adhesion layer on the first surface was 1.65, and the refractive index of the easy-adhesion layer on the second surface was 1.58.

  In addition, the refractive index of PET film measured the refractive index of the PET film manufactured on the conditions similar to the above except not laminating | stacking an easily bonding layer on both surfaces, and made the value the refractive index of PET film.

<Lamination of hard coat layer>
The hard coat layer-forming coating composition is applied on the second adhesive surface of the PET film prepared above by a wet coating method (gravure coating method), dried at 90 ° C., and then irradiated with ultraviolet rays of 500 mJ. / Cm ^{2 was} irradiated and cured to form a hard coat layer. This hard coat layer had a thickness of 2.5 μm.

<Formation of carbon nanotube layer>
The hard coat layer is laminated on the easy-adhesion layer on the first surface of the PET film, and the above-mentioned composition for forming a carbon nanotube layer is applied by a slot die coating method so that the solid content is 20 mg / m ^2. After coating, the carbon nanotube layer was formed by drying at 80 ° C. for 1 minute.

<Application of overcoat layer>
The overcoat layer-forming coating composition oc1 was coated on the carbon nanotube layer coated and formed by the slot die coating method and dried at 125 ° C. for 30 seconds. The coating amount (solid content coating amount) of the overcoat layer was adjusted so that the thickness of the conductive layer (the conductive layer if the carbon nanotube layer and the overcoat layer) was 100 nm.

[Examples 2-3 and Comparative Examples 1-2]
A conductive laminate was prepared in the same manner as in Example 1 except that the easy-adhesion layer on the first surface of the PET film was changed as shown in Table 1 in Example 1.

[Comparative Examples 3 to 5]
In Comparative Example 2, a conductive laminate was produced in the same manner as in Comparative Example 2 except that the overcoat layer was changed as shown in Table 1.

[Examples 4 to 6]
In Examples 1 to 3, conductive laminates were produced in the same manner as in Examples 1 to 3, except that the thickness of the easy-adhesion layer was changed to 20 nm.

[Evaluation]
About Examples 1-6 produced above and Comparative Examples 1-5, the luminous reflectance of the conductive layer surface and the adhesiveness of the conductive layer were evaluated. The results are shown in Table 1.

  From the results in Table 1, it can be seen that all of the examples of the present invention have low luminous reflectance and good adhesion of the conductive layer.

  On the other hand, Comparative Examples 1 to 5 have a high luminous reflectance since the refractive index of the easy-adhesion layer is less than 1.61.

[Examples 7 to 9 and Comparative Examples 6 to 7]
A conductive laminate was prepared in the same manner as in Example 4 except that the overcoat layer was changed as shown in Table 2 in Example 4. However, the overcoat layers of Comparative Examples 6 and 7 were of an ultraviolet curable type, and were cured by irradiation with 500 mJ / cm ^{2 of} ultraviolet light after coating and drying.

[Evaluation]
About Examples 7-9 and Comparative Examples 6-7 produced above, the luminous reflectance of the conductive layer surface and the adhesion of the conductive layer were evaluated. The results are shown in Table 2.

  From the results in Table 2, it can be seen that all the examples of the present invention have low luminous reflectance and good adhesion of the conductive layer.

  On the other hand, in Comparative Examples 6 to 7, the refractive index of the overcoat layer is higher than 1.46, so the luminous reflectance is high.

[Examples 10 to 13 and Comparative Examples 8 to 9]
A conductive laminate was produced in the same manner as in Example 4 except that the thickness of the conductive layer was changed as shown in Table 3 in Example 4.

[Evaluation]
About Examples 10-13 produced above and Comparative Examples 8-9, the luminous reflectance of the conductive layer surface and the adhesiveness of the conductive layer were evaluated. The results are shown in Table 3.

  From the results of Table 3, it can be seen that all of the examples of the present invention have low luminous reflectance and good adhesion of the conductive layer.

On the other hand, in Comparative Example 8, the luminous reflectance is high because the thickness of the conductive layer is smaller than 80 nm. In Comparative Example 9, the luminous reflectance is high because the thickness of the conductive layer is larger than 120 nm.

Claims (4)

  A polyethylene terephthalate film having a refractive index (n1) of 1.61-1.70 has a conductive layer composed of a carbon nanotube layer and an overcoat layer with an easy adhesion layer interposed therebetween, and the refractive index of the easy adhesion layer The conductive laminate, wherein (n2) is 1.61-1.70, the refractive index (n3) of the overcoat layer is 1.46 or less, and the thickness of the conductive layer is 80-120 nm. .   The conductive laminate according to claim 1, wherein the absolute value of the difference between the refractive index (n1) of the polyethylene terephthalate film and the refractive index (n2) of the easy-adhesion layer is 0.03 or less.   The conductive laminate according to claim 1, wherein the easy-adhesion layer has a thickness of 5 nm or more and less than 200 nm.   A touch panel using the conductive laminate according to claim 1.