JP2013008877A - Patterning method of composite layer including carbon nanotube layer and overcoat layer, and pattern formed by that method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a patterning method capable of removing a desired portion of a conductive film uniformly in the plane, and obtaining a high performance conductive film.SOLUTION: The patterning method of a composite layer having a carbon nanotube layer, and an overcoat layer covering the carbon nanotube layer includes a step for coating the overcoat layer, in a predetermined pattern, with an etching agent of the overcoat layer so that the carbon nanotube layer is etched together when the overcoat layer is etched, although the carbon nanotube layer is substantially not etched alone.

Description

  The present invention relates to a transparent conductive film that can be used for a transparent electrode of an optoelectronic device such as a display panel such as a liquid crystal display, a plasma display, or an organic EL display, a touch panel, or a solar cell.

  For example, a transparent conductive film substrate in which a transparent conductive film made of indium tin oxide (ITO) or the like is provided on a transparent substrate is known. This type of substrate is used in display panels such as liquid crystal displays, plasma displays, and organic EL displays. Or it is used for a touch panel. Or it is used for a solar cell. In addition, it is used in various fields. By the way, the transparent conductive film is formed in a desired pattern. As this pattern forming method, a chemical etching means (a photolithography means using a photoresist or an etchant) is generally employed.

  However, this chemical etching method uses a photoresist film forming process (applying a photoresist paint on the ITO film formed on the entire surface of the substrate) → photoresist film patterning process (exposure and development to form a predetermined pattern of the photoresist film) It is necessary to carry out many steps such as: ITO film etching step (etching the ITO film using a predetermined pattern of the photoresist film as a mask) → photoresist film removing step. In addition, this chemical etching method has problems in etching accuracy reduction due to swelling of the photoresist film in the solution, handling of the etchant, and waste liquid treatment.

  As a method for solving such a problem, a laser ablation method in which unnecessary portions are removed by directly irradiating a conductive film with a laser has been proposed. This method does not require a photoresist and enables highly accurate patterning.

  However, this method is limited to applicable substrates. Furthermore, the process cost is high and the processing speed is slow. Therefore, it is not a method suitable for a mass production process.

  Chemical etching techniques that do not require a photolithography process include “use of iron (III) chloride or iron (III) chloride hexahydrate as an etching component in a composition for etching an oxide surface”, “iron chloride” (III) or iron (III) chloride hexahydrate, in display technology (TFT), in photovoltaics, semiconductor technology, high performance electronics, mineralogy or glass industry, in OLED lighting, in the manufacture of OLED displays, and Use as an etching component in a composition in paste form for the manufacture of photodiodes and for the construction of ITO glass for flat panel screen applications (plasma displays) "" Composition for etching oxide layers " A) Chlorination as an etching component (III) or iron (III) chloride hexahydrate, b) solvent, c) optionally homogeneously dissolved organic thickener, d) optionally at least one inorganic and / or organic acid And optionally e) said composition comprising an additive such as an antifoaming agent, a thixotropic agent, a flow control agent, a degassing agent, an adhesion promoter, and is in paste form and printable. Table 2008-547232).

  “An etching medium for etching a transparent conductive layer of an oxide, comprising phosphoric acid or a salt thereof or a phosphoric acid adduct or a mixture of phosphoric acid and a phosphate and / or a phosphoric acid adduct “Etching medium containing at least one etchant” “A method for etching a transparent conductive layer of oxide, characterized in that the etching medium is applied to a substrate to be etched by a printing process” It has been proposed (Japanese translations of PCT publication No. 2009-503825).

  However, the techniques disclosed in JP-T-2008-547232 and JP-T-2009-503825 do not easily perform etching in the plane. For this reason, unevenness occurs.

  Incidentally, as the transparent conductive film, in addition to the transparent conductive film made of ITO, a transparent conductive film made of carbon nanotube is known. The carbon nanotube is a tube-shaped material having a diameter of 1 μm or less. A carbon nanotube having a carbon hexagonal mesh plane parallel to the axis of the tube to form a tube is ideal. In addition, this pipe may be multiplexed. Carbon nanotubes exhibit metallic or semiconducting properties depending on how the hexagonal network made of carbon is connected and the thickness of the tube. For this reason, it is expected as a functional material. However, depending on the configuration and manufacturing method of the carbon nanotube, the thickness and direction are random. For this reason, in use, it may be necessary to collect and purify after the synthesis and to process according to the form to be used. The following methods have been proposed as a method for patterning this type of carbon nanotube (Japanese Patent Publication No. 2006-513557, Japanese Patent Publication No. 2007-529884 (Pamphlet of International Publication No. 2005/086982)). For example, a carbon nanotube dispersion is applied to the substrate surface to form a carbon nanotube film. A binder solution is applied to the carbon nanotube film in a predetermined pattern. Thereafter, the solvent is dried. Thereby, the binder remains in the carbon nanotube film, and the network of carbon nanotubes is strengthened. Thereafter, the substrate is washed with a solvent that does not dissolve the binder. As a result, a pattern in which only the portion where the binder exists (to which the binder has been applied) remains is formed. A photoresist material can also be used instead of the binder. That is, a photoresist-containing paint is applied to the carbon nanotube film. Thereby, the photoresist is impregnated in the network of carbon nanotubes. Thereafter, a predetermined pattern is formed using photolithography. Alternatively, a preliminarily patterned carbon nanotube film may be formed directly on the substrate using a coating method such as screen printing, ink jet, or gravure printing.

  However, for example, the method of performing the patterning method after forming the carbon nanotube film on the entire surface of the substrate is complicated. When the patterned carbon nanotube film is directly formed by a coating method such as screen printing, it is necessary to adjust the physical properties of the carbon nanotube-containing coating material to the physical properties suitable for the coating method. The carbon nanotube dispersion liquid is generally adjusted by using a dispersant such as a surfactant. And it has a relatively low viscosity. However, in order to make the ink physical properties suitable for the coating method, a material for adjusting the viscosity and the surface tension is required for the carbon nanotube dispersion liquid. However, when other materials such as a solvent, fine metal particles, and a binder are mixed, the dispersibility of the carbon nanotubes may be deteriorated.

  The following technique is proposed (international publication 2010/113744 pamphlet) as an alternative to the technique proposed in Japanese Patent Publication No. 2006-513557 and Japanese Patent Publication No. 2007-529884. That is, an acid having a boiling point of 80 ° C. or higher (for example, sulfuric acid or a sulfonic acid compound), a base having a boiling point of 80 ° C. or higher, or a compound, solvent, resin (for example, primary to fourth that generates an acid or a base by external energy) Cationic resins containing any of the primary amino groups as part of the structure) and conductive film removing agents containing leveling agents have been proposed. Further, the conductive film removing agent is applied to at least a part of the base material with a conductive film having a conductive film containing a whisker-like conductor, a fibrous conductor (for example, carbon nanotube) or a particulate conductor on the base material. There has been proposed a conductive film removal method including a coating step, a heat treatment step at 80 ° C. or higher, and a step of removing the conductive layer by washing with a liquid. Further, there has been proposed a conductive film removal method for removing the overcoat layer and the conductive film from the substrate with the conductive film having an overcoat layer on the conductive film. Then, by applying heat treatment to 80 to 200 ° C. after applying the conductive film removing agent, the conductive film in the portion where the conductive film removing agent is applied is decomposed, dissolved or solubilized, and has an overcoat layer. In some cases, the overcoat layer and the conductive film are said to be decomposed, dissolved or solubilized.

Special table 2008-547232 gazette Special table 2009-503825 gazette JP-T-2006-513557 Special Table 2007-529884 (International Publication No. 2005/086982 Pamphlet) International Publication 2010/113744 Pamphlet

  However, the conductive film removing agent used in the technique of Patent Document 5 directly etches carbon nanotubes. For this reason, the carbon nanotube outside the etching region is also affected. That is, there is a high risk of causing defects in the carbon nanotubes outside the etching region. Furthermore, there is a high risk of etching carbon nanotubes outside the original etching region. This is highly likely that the pattern to be formed is not as designed. That is, it is difficult to form a conductive film with a highly accurate pattern. Furthermore, the technique of Patent Document 5 requires a heating step of heating the conductive film remover applied in a predetermined pattern to 80 ° C. or higher. Therefore, workability is poor. Furthermore, the substrate is required to have a heat resistance of 80 ° C. or higher. This reduces the degree of freedom in substrate selection.

  Therefore, the problem to be solved by the present invention is to solve the above problems. In particular, it is an object to provide a technique that eliminates the need for a heating step and that can hardly form an adverse effect on the remaining carbon nanotubes and that can form a highly accurate carbon nanotube layer pattern.

  The above-mentioned problems have been studied with eagerness. As a result, the problem of the technique of Patent Document 5 has been revealed to be due to the use of an agent that can directly remove carbon nanotubes by etching. Based on this revelation, further studies were promoted. Incidentally, an overcoat layer (protective layer) is usually provided on the surface of the carbon nanotube layer. It can be said that there is no case without an overcoat layer (protective layer). Therefore, although the carbon nanotubes cannot be directly etched, if the overcoat layer is etched, the above problem can be solved if the carbon nanotubes can be etched together by etching the overcoat layer. It came to obtain the knowledge of.

  The present invention has been achieved based on such findings.

That is, the above problem is
A method for forming a pattern of a composite layer comprising a carbon nanotube layer and an overcoat layer covering the carbon nanotube layer,
Although the carbon nanotube layer alone is not substantially etched, the carbon nanotube layer is etched together by an agent generated by etching the overcoat layer. The etchant for the overcoat layer is formed on the overcoat layer. In addition, the present invention is solved by a method for forming a pattern of a composite layer comprising a carbon nanotube layer and an overcoat layer, which comprises a coating step of coating in a predetermined pattern.

  Preferably, the composite layer pattern forming method includes the carbon nanotube layer and the overcoat layer, and further comprising a cleaning step in which cleaning is performed after the coating step. Solved.

Preferably, in the method for forming a pattern of a composite layer comprising the carbon nanotube layer and the overcoat layer, the carbon nanotube is a single-walled carbon nanotube (provided that G (a Raman common to a graphite material appearing in the vicinity of 1590 cm ^−1). Intensity at peak) / D (Intensity at Raman peak due to defects appearing in the vicinity of 1350 cm ⁻¹ ) ≧ 10).

  Preferably, the pattern forming method of the composite layer comprising the carbon nanotube layer and the overcoat layer, the overcoat layer includes an organic or inorganic material, an organic-inorganic hybrid resin, and the like. Examples of organic materials include thermoplastic resins, thermosetting resins, cellulose resins, photocurable resins, and inorganic materials such as silica sol, alumina sol, zirconia sol, titania sol, and water and acid catalysts for these inorganic materials. In addition, the invention is solved by a method for forming a pattern of a composite layer, which contains any one selected from the group of polymers hydrolyzed and dehydrated and condensed.

  Preferably, in the pattern forming method of the composite layer comprising the carbon nanotube layer and the overcoat layer, the agent applied on the overcoat layer is an organic solvent, an acidic material, an alkaline material, ammonium, an alkali metal, And a composite layer patterning method characterized by being selected from the group consisting of antimony fluoride, calcium acid fluoride, alkylated ammonium, and potassium tetrafluoroborate.

  The above-described problem is solved by a pattern formed by a method for forming a pattern of a composite layer including the carbon nanotube layer and an overcoat layer.

  For example, a transparent conductive film having a highly accurate pattern can be obtained. In addition, workability is good because a step of heating to 80 ° C. or higher is unnecessary.

Sectional view in the agent coating process of the present invention Sectional drawing which shows the etching condition after the agent application | coating of this invention Plan view of a pattern obtained by carrying out the present invention

The first aspect of the present invention is a pattern forming method. For example, it is a method of forming a transparent conductive film having a predetermined pattern. In particular, this is a method for forming a pattern of a composite layer comprising a carbon nanotube layer and an overcoat layer. The method includes a coating process. This application process is a process in which application is performed in a predetermined pattern. In particular, it is a process in which coating is performed on the overcoat layer. The agent used in this coating step is an agent that cannot substantially etch the carbon nanotube layer with this agent alone. However, the agent is an agent that can etch the overcoat layer. Prior to this coating step, for example, a step of providing a carbon nanotube layer on a substrate is included. For example, the method includes a step of applying a carbon nanotube dispersion on a substrate. After this carbon nanotube dispersion liquid coating step, for example, there is a step of providing an overcoat layer on the carbon nanotube layer. For example, it has the process of apply | coating an overcoat layer constituent material containing coating material. The method preferably further comprises a cleaning step performed after the coating step. The carbon nanotube is preferably a single-walled carbon nanotube (provided that G (intensity at a Raman peak common to a graphite substance appearing in the vicinity of 1590 cm ⁻¹ ) / D (intensity at a Raman peak due to a defect appearing near 1350 cm ⁻¹ ). ) ≧ 10). The practical upper limit value of G / D is about 150, for example. The overcoat layer is preferably an organic or inorganic material, an organic-inorganic hybrid resin, or the like. Examples of the organic material include a thermoplastic resin, a thermosetting resin, a cellulose resin, a photocurable resin, Examples of the inorganic material include silica sol, alumina sol, zirconia sol, titania sol, and any resin selected from the group of polymers obtained by hydrolysis and dehydration condensation by adding water or an acid catalyst to these inorganic materials. A particularly preferable overcoat layer comprises a composition containing a tetrafunctional hydrolyzable organosilane, a hydrolyzate of a hydrolyzable organosilane having an epoxy group and an alkoxy group, and silica-based metal oxide fine particles. It is. The agent applied on the overcoat layer is preferably an organic solvent, acidic material, alkaline material, ammonium, alkali metal and antimony fluoride, calcium acidic fluoride, alkylated ammonium, and tetrafluoroboric acid One selected from the group of potassium. Particularly preferred is ammonium fluoride as a material corresponding to the overcoat layer that is suitably used.

  The second aspect of the present invention is a pattern formed by performing the pattern forming method.

  Further detailed description will be given below.

  1 to 3 are for explaining one embodiment of the present invention, FIG. 1 is a cross-sectional view in the agent coating process of the present invention, and FIG. 2 is a cross-sectional view showing the etching condition after the agent coating of the present invention. FIG. 3 is a plan view of a pattern obtained by carrying out the present invention.

  In each figure, 1 is a conductive film (transparent conductive film) composed of carbon nanotubes.

  Examples of the carbon nanotube (CNT) constituting the conductive film (particularly the transparent conductive film) 1 include single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes. Among these, single-walled carbon nanotubes are preferable. In particular, single-walled carbon nanotubes having a G / D of 10 or more (for example, 20 to 60) are preferable. Furthermore, CNT having a diameter of 0.3 to 100 nm is preferable. In particular, CNT having a diameter of 0.3 to 2 nm is preferable. Further, CNTs having a length of 0.1 to 100 μm are preferable. In particular, CNT having a length of 0.1 to 5 μm is preferable. The CNTs in the conductive film (transparent conductive film) 1 are intertwined with each other.

  The single-walled carbon nanotube may be a single-walled carbon nanotube obtained by any manufacturing method. For example, single-walled carbon nanotubes obtained by production methods such as arc discharge, chemical vapor deposition, and laser evaporation can be used. However, single-walled carbon nanotubes obtained by an arc discharge method are preferred from the viewpoint of crystallinity. And this thing is also easily available. The single-walled carbon nanotube is preferably a single-walled carbon nanotube subjected to acid treatment. The acid treatment is performed by immersing single-walled carbon nanotubes in an acidic liquid. A technique called spraying may be employed instead of immersion. Various kinds of acidic liquids are used. For example, an inorganic acid or an organic acid is used. However, inorganic acids are preferred. For example, nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, or a mixture thereof can be used. Among these, acid treatment using nitric acid or a mixed acid of nitric acid and sulfuric acid is preferable. By this acid treatment, when single-walled carbon nanotubes and carbon microparticles are physically bonded via amorphous carbon, the amorphous carbon is decomposed and separated from each other, or the metal used when producing single-walled carbon nanotubes The fine particles of the catalyst will be decomposed. And the electroconductivity was improving by the acid treatment. The single-walled carbon nanotube is preferably a single-walled carbon nanotube in which impurities are removed by filtration and purity is improved. This is because a decrease in conductivity and a decrease in light transmittance due to impurities are prevented. Various methods are employed for filtration. For example, suction filtration, pressure filtration, cross flow filtration and the like are used. Among these, from the viewpoint of scale-up, it is preferable to employ cross flow filtration using a hollow fiber membrane.

  The conductive film (particularly the transparent conductive film) 1 preferably contains fullerene in addition to the CNT. That is, the conductive film (in particular, the transparent conductive film) 1 preferably contains the above-described CNT and fullerene. In the present specification, “fullerene” includes “fullerene analog”. This is because heat resistance is improved by including fullerene. Moreover, it is because it was excellent also in electroconductivity. The fullerene may be any fullerene. For example, C60, C70, C76, C78, C82, C84, C90, C96 etc. are mentioned. Of course, a mixture of plural kinds of fullerenes may be used. C60 is particularly preferable from the viewpoint of dispersion performance. Furthermore, C60 is easy to obtain. Not only C60 but also a mixture of C60 and another kind of fullerene (for example, C70) may be used. The fullerene may contain metal atoms. Examples of the fullerene analog include those containing a functional group (for example, a functional group such as OH group, epoxy group, ester group, amide group, sulfonyl group, ether group). Moreover, what has phenyl-C61-propyl acid alkyl ester and phenyl-C61-butyric acid alkyl ester is also mentioned. In addition, hydrogenated fullerene is also included. Among them, fullerene having an OH group (hydroxyl group) (fullerene hydroxide) is preferable. This is because the dispersibility during coating of the single-walled carbon nanotube dispersion was high. In addition, when there is little quantity of a hydroxyl group, the dispersibility improvement degree of a single-walled carbon nanotube will fall. On the other hand, if too much, synthesis is difficult. Therefore, the amount of OH groups is preferably 5 to 30 per molecule of fullerene. In particular, 8 to 15 are preferable. When there is too much addition amount (content) of fullerene, electroconductivity will fall. Conversely, if the amount is too small, the effect is poor. Therefore, the amount of fullerene is preferably 10 to 1000 parts by mass (particularly 20 parts by mass or more and 100 parts by mass or less) with respect to 100 parts by mass of CNTs.

  In addition, the electrically conductive film (especially transparent electrically conductive film) 1 may contain binder resin. However, from the viewpoint of conductivity, it is preferable not to include a binder resin. For example, if a structure in which CNTs are intertwined is used, there is no need for a binder resin. That is, the CNTs are in direct contact with each other. Therefore, since there is no intervening insulator, the conductivity is good. If the surface of the conductive film is observed with a scanning electron microscope, it can be confirmed / determined whether the structure is intertwined with CNTs.

  The conductive film (transparent conductive film) 1 is configured by applying a dispersion liquid in which the above-described CNTs and the fullerene added as necessary are dispersed on the substrate 2. Examples of the coating method include die coating, knife coating, spray coating, spin coating, slit coating, micro gravure, flexo and the like. Of course, it is not limited to this. Application is performed on the entire surface of the substrate 2.

  Various materials are appropriately used as the constituent material of the substrate 2. For example, polystyrene (PS), polymethyl methacrylate (PMMA), styrene-methyl methacrylate copolymer (MS), polycarbonate (PC), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene terephthalate (PET), A resin such as polyethylene naphthalate (PEN) is used. In the present invention, since heating is not required for patterning the conductive film, the required degree of heat resistance is low. Therefore, even when a resin is used as the constituent material of the substrate 2, the degree of freedom in resin selection is high. In addition to the resin, an inorganic glass material or a ceramic material can be used.

  In the present invention, an overcoat film (protective film) 3 is provided on a conductive film (particularly a transparent conductive film) 1. The overcoat film (protective film) 3 is composed of an organic or inorganic polymer material, an organic-inorganic hybrid resin, or the like. Examples of organic polymer materials include thermoplastic resins, thermosetting resins, cellulose resins, and photocurable resins. It is appropriately selected from the viewpoints of visible light transmittance, substrate heat resistance, glass transition point, film curing degree, and the like. Examples of the thermoplastic resin include polymethyl methacrylate, polystyrene, polyethylene terephthalate, polycarbonate, polylactic acid, and ABS resin. Examples of the thermosetting resin include phenol resin, melamine resin, alkyd resin, polyimide, epoxy resin, fluorine resin, and urethane resin. Examples of the cellulose resin include acetyl cellulose and triacetyl cellulose. Examples of the photocurable resin include various oligomers, monomers, resins containing a photopolymerization initiator, and the like. Examples of the inorganic material include silica sol, alumina sol, zirconia sol, titania sol and the like. Moreover, the polymer etc. which hydrolyzed and dehydrated and condensed the said inorganic material by adding water and an acid catalyst are mentioned. Examples of the organic-inorganic hybrid resin include those in which a part of the inorganic material is modified with an organic functional group, and resins mainly composed of various coupling agents such as a silane coupling agent. If the overcoat film 3 is too thick, the contact resistance of the conductive film 1 increases. Conversely, if the overcoat film 3 is too thin, it is difficult to obtain an effect as a protective film. Therefore, the thickness of the overcoat film 3 is preferably 1 nm to 1 μm. In particular, 10 nm or more is preferable. Moreover, 100 nm or less is preferable.

  The overcoat film (protective film) 3 provided on the conductive film (especially transparent conductive film) 1 in the present invention is preferably composed of a composition containing a hydrolyzate of hydrolyzable organosilane. More preferably, it consists of a composition containing a tetrafunctional hydrolyzable organosilane. In particular, it comprises a composition containing a hydrolyzate of a tetrafunctional hydrolyzable organosilane and a hydrolyzable organosilane having an epoxy group and an alkoxy group. Among these, the content of the hydrolyzable organosilane hydrolyzate having an epoxy group and an alkoxy group is preferably 1 to 10% by weight based on the total solid content of the resin. When a hydrolyzable organosilane cohydrolyzate having an epoxy group and an alkoxy group is contained, and the composition containing these is applied and cured, the epoxy group of the cohydrolyzate is contained in the substrate. It binds to oxygen sites such as hydroxyl groups and carbonyl groups. For this reason, the adhesion between the overcoat film (protective film) and the substrate is improved. Furthermore, it consists of a composition containing silica-based metal oxide fine particles. In some cases, the composition further comprises a hydrolyzate of hydrolyzable organosilane having a fluorine-substituted alkyl group. The hydrolyzate of the hydrolyzable organosilane is preferably a product obtained by reacting at a water ratio of 1.0 to 3.0 with respect to the alkoxy group contained in the hydrolyzable organosilane. The hydrolyzate of the hydrolyzable organosilane is preferably a compound having a polystyrene-equivalent weight average molecular weight of 1000 to 2000.

The tetrafunctional hydrolyzable organosilane is a compound represented by, for example, SiX ₄ . X is a hydrolyzable group. For example, an alkoxy group, an acetoxy group, an oxime group, an enoxy group, and the like. In particular, it is a tetrafunctional hydrolyzable organoalkoxysilane represented by Si (OR ¹ ) ₄ . R ¹ is preferably a monovalent hydrocarbon group. For example, it is a monovalent hydrocarbon group having 1 to 8 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group and octyl group. Examples of the tetrafunctional hydrolyzable organosilane used in the present embodiment include tetramethoxysilane and tetraethoxysilane. The hydrolyzable organosilane having an epoxy group and an alkoxy group is, for example, a compound represented by R ² Si (OR ³ ) ₃ or R ² R ⁴ Si (OR ³ ) ₂ . R ² is a group selected from an epoxy group, a glycidoxy group, and substituted products thereof. R ³ is a monovalent hydrocarbon group as in R ¹ . For example, methyl group, ethyl group, propyl group, butyl group, pentyl group and the like. R ⁴ is a group selected from hydrogen, an alkyl group, a fluoroalkyl group, an aryl group, an alkenyl group, a methacryloxy group, an epoxy group, a glycidoxy group, an amino group, and substituents thereof. Examples of the hydrolyzable organosilane having an epoxy group and an alkoxy group used in this embodiment include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropyltrisilane. Examples thereof include ethoxysilane and γ-glycidoxypropyldimethoxymethylsilane. As silica-based metal oxide fine particles, hollow silica fine particles are preferably used. The hollow silica fine particles are those in which cavities are formed inside the outer shell of the silica-based metal oxide. The outer shell is preferably a porous one having pores. It may be one in which the pores are closed and the cavity is sealed. Note that the silica is not limited to the above-described hollow silica as long as it contributes to lowering the refractive index of the formed film.

  In the case of an overcoat film having such a composition, the light reflectance is lowered and the light transmittance is increased. Furthermore, physical protection against friction and the like is high. In addition, protection against environmental changes such as heat and humidity is high. A further point of interest is that when the overcoat film 3 of this embodiment is etched, the underlying carbon nanotube film 1 is also etched.

  The overcoat film (protective film) 3 is provided by applying a paint containing the above composition. As the application method, the method described in the application of the CNT dispersion liquid is employed. Application is performed on a conductive film (transparent conductive film: carbon nanotube layer). Moreover, it is applied to the entire surface.

  In the present invention, the conductive film (transparent conductive film: carbon nanotube layer) 1 alone is not etched, but the conductive film (transparent conductive film) is formed by the agent produced (generated) by etching the overcoat film (protective film) 3. (Membrane: Carbon nanotube layer) An agent for etching 1 was used. In other words, the conductive film (transparent conductive film: carbon nanotube layer) 1 is not etched only with the etching agent 4 used in the present invention (or the etching rate is very slow, so the etching is considered to be performed. I ca n’t lose weight). However, the overcoat film (protective film) 3 is etched. In addition, the conductive film (transparent conductive film: carbon nanotube layer) 1 can be etched by the agent produced (generated) by etching the overcoat film (protective film) 3. Therefore, there is little adverse effect on the carbon nanotube.

  When such an agent is described in the case where the overcoat film 3 is composed of a composition containing a hydrolyzate of the hydrolyzable organosilane, the following examples can be given. For example, an agent (for example, at least one selected from the group of antimony fluoride, calcium acid fluoride, alkylated ammonium, and potassium tetrafluoroborate) containing ammonium, an alkali metal, and a fluorine compound ( Etching agent). This agent (etching agent) further contains an inorganic acid (for example, an acid selected from the group of hydrochloric acid, phosphoric acid, sulfuric acid and nitric acid) as necessary. Moreover, an organic acid is contained as needed. Examples of the organic acid include alkyl carboxylic acid, hydroxy carboxylic acid, and / or dicarboxylic acid. Especially, the organic acid which can contain a C1-C10 linear or branched alkyl radical is mentioned.

  The etching agent (liquid) is applied on the overcoat film 3. As a coating method, various patterning printing methods are adopted. For example, techniques such as screen printing, flexo, and ink jet are used.

  After the etching agent (liquid) is applied on the overcoat film 3, it is left as it is for a predetermined time. For example, it is left for about 10 seconds to 20 minutes. As a result, etching proceeds. Thereafter, ultrasonic cleaning was performed in pure water. As a result, the pattern shown in FIGS. 2 and 3 was formed.

  Hereinafter, description will be made with specific examples. However, the present invention is not limited to the following examples.

[Example 1]
The single wall carbon nanotubes (commercially available) synthesized by arc discharge were subjected to acid treatment, water washing, centrifugation and filtration. A 0.2 wt% aqueous solution of a surfactant TritonX-100 (manufactured by GE Healthcare) was added to the carbon nanotubes obtained by this purification. The carbon nanotube-containing aqueous solution was subjected to a dispersion treatment using ultrasonic waves. Centrifugation was then performed. In this way, a carbon nanotube dispersion (CNT: 1000 ppm) was obtained.

  The carbon nanotube dispersion liquid was applied. The application method is die coating. The coating thickness is 0.05 μm after drying. As the substrate, PET film A4100 (manufactured by Toyobo Co., Ltd.) was used. After application, methanol washing was performed to remove the surfactant contained in the coating film. Then, drying (1 minute; 100 ° C.) was performed.

  An overcoat film was provided on the carbon nanotube coating film. The overcoat film was composed of 3.8 wt% Aerocera (hydrolyzable organosilane-containing composition: manufactured by Panasonic Electric Works Co., Ltd.). The application method is die coating. The coating thickness is 0.1 μm after drying.

  Thereafter, an etching solution (containing ammonium hydrogen fluoride: isishape Hiper Etch 11S (manufactured by Merck)) was printed in a predetermined pattern on the overcoat film. The printing method is a screen printing method. The printing pattern of the screen plate is □ (see FIG. 3), has an opening with a line width of 100 μm, and has a line length of 5 mm.

  After the etching solution was printed, it was left for 1 minute. Subsequently, ultrasonic cleaning was performed in pure water. Then, it was pulled out from water and dried.

  The conduction between the inside and outside of the pattern (□) was examined by using a tester. As a result, it was found that there was no conduction (insulation) between the two.

  Furthermore, when the printing pattern (□) of the screen plate was compared with the pattern (□) of the carbon nanotube film, the accuracy was high.

[Comparative Example 1]
In Example 1, everything was performed in the same manner except that no overcoat film was provided.

  As a result, conduction was confirmed between the inside and outside of the printed pattern (□). That is, it was confirmed that the carbon nanotube film was not etched.

[Comparative Example 2]
In Example 1, pattern formation was performed by the same process as in Example 1 except that the overcoat layer was not formed and the etching medium was changed to isisshape HiperEtch 4S (manufactured by Merck) capable of etching ITO. Could not be etched, and conduction was confirmed.
That is, with an etching agent as shown in International Publication No. 2010/113744 pamphlet, CNT cannot be etched even if ITO can be etched.

1 Conductive film (Transparent conductive film: Carbon nanotube layer)
2 Substrate 3 Overcoat film (Protective film: Overcoat layer)
4 Etching agent (agent applied on overcoat layer)

Claims (8)

A method for forming a pattern of a composite layer comprising a carbon nanotube layer and an overcoat layer covering the carbon nanotube layer,
Although the carbon nanotube layer alone is not substantially etched, an etching agent for the overcoat layer in which the carbon nanotube layer is etched together by etching the overcoat layer is provided on the overcoat layer. A pattern forming method for a composite layer comprising a carbon nanotube layer and an overcoat layer, comprising a coating step of coating in a pattern. The method for forming a pattern of a composite layer comprising a carbon nanotube layer and an overcoat layer according to claim 1, further comprising a washing step in which washing is performed after the coating step. The carbon nanotube is a single-walled carbon nanotube (provided that G (intensity at a Raman peak common to a graphite substance appearing near 1590 cm −1) / D (intensity at a Raman peak due to defects appearing near 1350 cm −1) ≧ 10) A method for forming a pattern of a composite layer comprising the carbon nanotube layer according to claim 1 or 2 and an overcoat layer. 4. The carbon nanotube layer according to claim 1, wherein the overcoat layer contains any one selected from the group consisting of an organic material, an inorganic material, and an organic-inorganic composite material. And pattern formation method of a composite layer comprising an overcoat layer. The overcoat layer is composed of a hydrolyzable organosilane hydrolyzate-containing composition, wherein the composite layer comprising the carbon nanotube layer according to any one of claims 1 to 3 and the overcoat layer. Pattern forming method. Agents applied on the overcoat layer are organic solvents, acidic materials, alkaline materials, ammonium, alkali metal fluorides, antimony fluorides, calcium acid fluorides, ammonium alkylates, and potassium tetrafluoroborate. 6. The method for forming a pattern of a composite layer comprising the carbon nanotube layer and the overcoat layer according to claim 1, wherein the pattern is any one selected from the group. 7. A method for forming a pattern of a composite layer comprising a carbon nanotube layer and an overcoat layer according to claim 1, which is a method for forming a transparent conductive film having a predetermined pattern. A pattern formed by the method of forming a composite layer pattern comprising the carbon nanotube layer according to claim 1 and an overcoat layer.