Method for manufacturing conductive films, touch panels, display panels

Abstract

To provide an organic resin material which can keep a carbon material having conductivity uniformly anchored over an entire conductive film formation region, and to provide a method for manufacturing a conductive film using an organic resin material, as well as a touch panel, display panel comprising a conductive film manufactured by the manufacturing method.SOLUTION: This method includes: a process (A) of forming an organic resin layer by coating a substrate with an organic resin material containing a polymer obtained by making acid anhydride react with aromatic diamine containing a heterocyclic structure; a process (B) of forming a coat film by coating, after the execution of the process (A), the organic resin layer with a fluid dispersant containing a dispersant and a carbon nano-tube; a process (C) of drying the coat film after the execution of the process (B); a process (D) of removing the dispersant from the coat film by depositing a dispersant extract after the execution of the process (C).SELECTED DRAWING: Figure 4

Description

【Technical Field】 【0001】 The present invention relates to a method for manufacturing a conductive film. The present invention also relates to a touch panel and a display panel. 【Background Art】 【0002】 In recent years, semiconductor devices having electrodes and wirings formed of a conductive film made of a nanocarbon material have been developed. Conventionally, electrodes and wirings of semiconductor devices have often been formed of metals such as copper and aluminum. However, nanocarbon materials, particularly carbon nanotubes (hereinafter sometimes abbreviated as "CNT"), can be configured to be much thinner than metals and metal oxide films and exhibit high conductivity, and thus have attracted high attention as materials for semiconductor devices. In addition, since a conductive film formed of a nanocarbon material can form a film having high transparency to visible light, there is a trend to actively adopt it for semiconductor optical elements. 【0003】 Based on the above background, various proposals have been made regarding materials and manufacturing methods, particularly for conductive films made of CNT. For example, Patent Document 1 below discloses a composition containing a solvent and CNT as a composition with enhanced dispersibility of CNT. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2010-214837 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, conductive films produced by the above compositions have the problem of being prone to aggregation during drying processes, which can impair their homogeneity. In transparent CNT conductive films, the fibrous CNTs overlap like a nonwoven fabric, forming circuits through which current flows and exhibiting conductivity. Therefore, unlike metal films or metal oxide films, it is difficult to configure them to have stable properties, and it is difficult to achieve stable electrical characteristics. 【0006】 In particular, with the increasing miniaturization of semiconductor devices such as LSIs, the wiring width is extremely narrow. When wiring is formed using conductive films of carbon nanotubes (CNTs), there are challenges such as the formation of wiring with high resistance in certain areas or a high likelihood of disconnection. 【0007】 Furthermore, when used in light-emitting elements or touch panels, it is necessary to form the conductive film as thinly as possible to enhance transmittance to visible light, and high conductivity and the formation of a homogeneous conductive film are required. In such cases, as with semiconductor devices such as LSIs mentioned above, the problem of conductive film breakage occurs. More specifically, for example, when wiring constituting a touch panel is constructed with a width of 50 μm or less, or when creating lead wires from contact holes of 50 μm or less when creating pixel electrodes for a display panel, breakage is particularly likely to occur. 【0008】 In view of the above problems, the present invention aims to provide an organic resin material that can evenly fix a conductive carbon material throughout the entire conductive film formation region, as well as a method for manufacturing a conductive film using the organic resin material, and a touch panel or display panel equipped with a conductive film manufactured by the said manufacturing method. [Means for solving the problem] 【0009】 The method for manufacturing a conductive film of the present invention is: Step (A) involves applying an organic resin material containing a polymer obtained by reacting an acid anhydride with an aromatic diamine containing a heterocyclic structure onto a substrate to form an organic resin layer. After performing step (A), step (B) is performed, in which a dispersion containing a dispersant and carbon nanotubes is applied to the organic resin layer to form a coating film. After performing step (B), step (C) is performed to dry the coating film, The process includes step (D) after performing step (C) above, by applying a dispersant extract to remove the dispersant from the coated film. 【0010】 In the above manufacturing method, Step (D) may also be a step of removing the dispersant from the coating film by immersing the substrate in a dispersant extract. 【0011】 In the above manufacturing method, The above step (D) may also be a step of immersing in the dispersant extract, which consists of an alkaline aqueous solution. 【0012】 The above manufacturing method is The polymer may also be a polymer having a moiety derived from an aromatic diamine having at least one heterocyclic structure selected from the following formulas (1), (2), and (3). 【0013】 [ka] In equations (1) to (3), X represents O, S, or N. When X is O or S, n is 0, and when X is N, n is 1. Y is any organic group. R is a monovalent organic group, which may or may not form a ring, and m is a number from 1 to 4. p, q, and r are 0 or numbers greater than or equal to 1, and the numbers of p, q, and r may be the same or different. 【0014】 In the above manufacturing method, The above step (B) may also be a step of applying the dispersant containing an alkali-soluble polymer having one functional group selected from the group consisting of carboxyl groups, hydroxyl groups, and phenolic hydroxyl groups. 【0015】 In the above manufacturing method The step (B) may be a step of applying the dispersion liquid containing the dispersant containing a polymer having a polyamic acid structure and an organic solvent onto the organic resin layer. 【0016】 In the above manufacturing method, The step (B) may be a step of applying the dispersion liquid in which the content of the dispersant with respect to the carbon nanotube is within the range of 1,000% by mass to 100,000% by mass onto the organic resin layer. 【0017】 The touch panel of the present invention includes a conductive film manufactured by the above manufacturing method. 【0018】 The display panel of the present invention includes a conductive film manufactured by the above manufacturing method. 【Advantages of the Invention】 【0019】 According to the present invention, there is provided an organic resin material capable of uniformly fixing a carbon material having conductivity over the entire conductive film forming region, a manufacturing method of a conductive film using the organic resin material, and a touch panel and a display panel including the conductive film manufactured by the manufacturing method. Furthermore, according to the present invention, since peeling of the conductive film from the substrate is less even by treatment with strong alkaline water such as alkali development, an excellent conductive film with few electrical defects can be formed. 【Brief Description of the Drawings】 【0020】 [Figure 1] It is a schematic diagram showing the overall configuration of an embodiment of a display panel. [Figure 2] It is a drawing schematically showing the step of forming a conductive film. [Figure 3] It is a drawing schematically showing the step of forming a conductive film. [Figure 4] It is a drawing schematically showing the step of forming a conductive film. 【Embodiments for Carrying Out the Invention】 【0021】 The following describes, first, the configuration of the display panel 1 as one embodiment, and then, the details of one embodiment of the method for manufacturing the conductive film on the display panel 1. Finally, a verification and evaluation experiment was conducted to confirm the effects of the present invention using one embodiment of the method for manufacturing the conductive film of the present invention, and the details of this verification and evaluation experiment are described. 【0022】 [Display panel] The overall configuration of one embodiment of the display panel 1 will be described. Figure 1 is a schematic diagram showing the overall configuration of one embodiment of the display panel 1. The display panel 1 has a base material 2, and one surface of the base material 2 is provided with an element region 2a and a peripheral region 2b. 【0023】 The substrate 2 is made of a light-transmitting material, specifically, a glass substrate, a quartz substrate, or an organic resin substrate. An example of an organic resin substrate material is polyimide. The organic resin substrate can have a thickness of several micrometers to tens of micrometers, making it possible to realize a flexible sheet display. 【0024】 Element region 2a is a region in which elements for displaying an image are formed. Element region 2a is provided with a lower electrode, and an insulating layer is provided on the lower electrode. An organic resin layer is provided on the insulating layer, and a conductive film is provided on the organic resin layer. 【0025】 Regarding organic resin materials, the present invention relates to polymers obtained by reacting acid anhydrides with heterocyclic aromatic diamines. The organic resin material used in this invention is a polymer obtained by reacting acid anhydrides with heterocyclic aromatic diamines, and because it has aromatic rings and heterocyclic structures within its molecule, the resulting polymer is rich in structures having π-π bonds. Therefore, it is expected to have a high degree of interaction with carbon materials such as carbon nanotubes (CNTs), which are also rich in structures having π-π bonds. 【0026】 One mechanism by which carbon materials such as CNTs are solubilized (dispersed) in solvents is physical adsorption due to π-π interactions between CNTs and benzene rings. It is thought that polymers with such physical adsorption capacity promote solubilization (dispersion) by wrapping around the CNT chains. This is thought to be an attempt to maximize the surface area for physical adsorption with the CNTs. In the organic resin layer of the present invention, there is an abundance of π-π bonds derived from aromatic rings, resulting in a tendency for high CNT adhesion. Therefore, it is thought that the magnitude of the physical adsorption described above is influencing this. 【0027】 Furthermore, although the reason why having a heterocyclic structure improves CNT adhesion is not clear, it is thought to have the effect of increasing the surface area on which CNTs and polymers physically adsorb. 【0028】 The polymer obtained by reacting the acid anhydride with an aromatic diamine having a heterocyclic structure is a polymer having a constituent site represented by the following formula (4). 【0029】 [ka] (In formula (4), A is a tetravalent organic group constituting a tetracarboxylic acid, B is a divalent organic group constituting a diamine, and a represents a positive integer.) 【0030】 In formula (4), B preferably contains at least one heterocyclic structure from the following formulas (1) to (3). 【0031】 [ka] In equations (1) and (2), X represents O, S, or N. When X is O or S, n is 0, and when X is N, n is 1. Y is any organic group. R is a monovalent organic group, which may or may not form a ring, and m is a number from 1 to 4. p, q, and r are 0 or numbers greater than or equal to 1, and the numbers of p, q, and r may be the same or different. 【0032】 The structure of A in formula (4) above, which is obtained by polymerizing acid dianhydrides, is not particularly limited, but examples include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, and the like. 【0033】 When it is desirable to fix a larger amount of carbon material, it is preferable to use aromatic tetracarboxylic dianhydride. 【0034】 Specific examples of the above-mentioned tetracarboxylic dianhydrides include aliphatic tetracarboxylic dianhydrides such as butanetetracarboxylic dianhydride and ethylenediaminetetraacetic acid dianhydride; As alicyclic tetracarboxylic dianhydrides, these include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, and 3-oxabicyclo[3.2 .1] Octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid 2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.0 2,6 Undecane-3,5,8,10-tetraone, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, etc. Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-biphthalic dianhydride, 4,4'-carbonyl diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,4,5,6-tetracarboxylic dianhydride, ethylene glycol bis(anhydrotrimellitate), 1,3-propylene glycol bis(anhydrotrimellitate), etc. In addition to the above, the tetracarboxylic dianhydride described in Japanese Patent Publication No. 2010-97188 can be used. 【0035】 The material for the organic resin layer can be synthesized by combining the above-mentioned acid anhydride with a diamine having a heterocyclic structure using a method similar to that used for existing polyamic acids. The material for the conductive film formed from such an organic material containing polymers is carbon nanotubes (CNTs). As for the type of CNT, single-walled carbon nanotubes or multi-walled carbon nanotubes with two or more layers can be used, and single-walled carbon nanotubes are preferred. 【0036】 Conductive films made from carbon nanotubes exhibit varying transmittance depending on the film thickness, but they are transparent conductive films that transmit visible light. 【0037】 The coated film is formed by applying a dispersion containing carbon nanotubes and a dispersant. The dispersant is not particularly limited, but it is preferable to use a polyamic acid having the structural site shown in formula (5) in order to improve the dispersibility of carbon nanotubes. 【0038】 [ka] (In formula (5), D is a tetravalent organic group constituting a tetracarboxylic acid, E is a divalent organic group constituting a diamine, and b is a positive integer.) 【0039】 Specific examples of the tetravalent organic group constituting the tetracarboxylic acid represented by D include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3,6,7-anthracenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4-biphenyltetracarboxylic acid, bis(3,4-dicarboxyphenyl) ether, 3,3',4,4'-benzophenonetetracarboxylic acid, bis(3,4-dicarboxyphenyl) sulfone, bis(3,4-dicarboxyphenyl) methane, 2,2-bis(3,4-dicarboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2- Examples include dianhydrides of aromatic tetracarboxylic acids such as bis(3,4-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl)dimethylsilane, bis(3,4-dicarboxyphenyl)diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, and 2,6-bis(3,4-dicarboxyphenyl)pyridine; dianhydrides of tetracarboxylic acids having an alicyclic structure such as 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 2,3,5-tricarboxycyclopentylacetic acid, and 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid; and dianhydrides of aliphatic tetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid. These acid dianhydrides may be used as a single compound or in combination of multiple compounds. 【0040】 Specific examples of divalent organic groups that constitute diamines represented by E include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, diaminodiphenylmethane, diaminodiphenyl ether, 2,2'-diaminodiphenylpropane, bis(3,5-diethyl-4-aminophenyl)methane, diaminodiphenylsulfone, diaminobenzophenone, diaminonaphthalene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 1,3-bis(4-aminophenyl Examples include aromatic diamines such as (xy)benzene, 4,4'-bis(4-aminophenoxy)diphenylsulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane; alicyclic diamines such as bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, and 3,5-cholestanil diaminobenzoate; aliphatic diamines such as 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, and 1,6-diaminohexane; and silicon diamines such as 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. These diamines may be used as a single compound or in combination of multiple compounds. 【0041】 Furthermore, it is preferable that D in formula (5) above is a cyclobutane ring. The cyclobutane ring is preferable because its ring structure decomposes upon light irradiation or heating, causing a structural change in the polyamic acid, which makes it easier to remove the dispersant. In addition, the dispersion may contain an organic solvent as a dispersion medium. 【0042】 [Manufacturing method] The method for manufacturing a conductive film will be explained with reference to Figures 2 to 4. Figures 2 to 4 are schematic diagrams showing the process of forming a conductive film. In this embodiment, the conductive film is fabricated on an insulating layer formed on a substrate. 【0043】 As shown in Figure 2, an organic resin material containing a polymer having hydrocarbon groups is applied to the substrate 2 in which the insulating layer 10 has been formed, thereby forming an organic resin layer 20 (corresponding to step (A)). 【0044】 As shown in Figure 3, a dispersion containing CNTs is applied to the organic resin layer 20 to form a pattern of the coating film 30 (corresponding to step (B)). For convenience, Figure 3 shows the coating film 30 formed over the entire surface of the organic resin layer 20. 【0045】 In this process, a pattern is formed on the organic resin layer 20 by coating a dispersion containing CNTs using printing techniques such as casting, screen printing, or inkjet printing. After the pattern is formed, as shown in Figure 4, the solvent contained in the coating film is removed by drying, and the CNTs are fixed on the organic resin layer 20 to form a conductive film 40 (corresponding to process (C)). 【0046】 In Figure 4, for convenience, the conductive film 40 is shown to be formed over the entire surface of the organic resin layer 20, but the pattern of the conductive film 40 can be adjusted as appropriate. 【0047】 After the solvent is removed by drying, a dispersant extract is applied to the conductive film formed on the substrate to remove the dispersant from the pattern formed by the applied film (corresponding to step (D)). In addition, in this step, in addition to the above method of forming the pattern of the conductive film by printing, a method can also be adopted in which the dispersion is applied to the entire organic resin layer formed on the substrate, dried and washed, and then a separate photosensitive resist layer for patterning is formed on the conductive film. In this case, after forming the photosensitive resist layer, the conductive layer is removed by etching, and the remaining photosensitive resist layer is removed. 【0048】 While the combination of dispersant and dispersant extract is arbitrary, it is preferable to use an alkali-soluble polymer having a functional group that improves solubility in alkaline aqueous solutions as the dispersant, and an alkaline aqueous solution as the dispersant extract. By using an alkaline aqueous solution as the dispersant extract, it becomes possible to selectively leave CNTs, which are difficult to disperse in alkaline aqueous solutions, on the organic resin layer. 【0049】 Furthermore, by using such an alkali-soluble polymer in the process, it becomes possible to share materials with other processes that use alkaline aqueous solutions for developing photosensitive resist layers, thereby greatly increasing productivity. 【0050】 Furthermore, suitable alkaline aqueous solutions include, for example, KOH (potassium hydroxide), NaOH (sodium hydroxide), sodium carbonate, and TMAH (tetramethylammonium hydroxide) aqueous solutions. 【0051】 Furthermore, these dispersants may contain molecular structures in the material that react to light or heat, undergoing decomposition or structural changes to improve their solubility in alkaline aqueous solutions. By using such dispersants, solubility can be improved by applying light or heat after the formation of a conductive film, and then a dispersant extract can be applied to further improve the efficiency of removing the dispersant from the pattern formed by the coated film. 【0052】 Molecular structures exhibiting such functions may include, for example, a dispersant polyamic acid structure that contains a moiety, such as cyclobutane, that can be decomposed by light or heat, thereby altering the overall structure of the polyamic acid. Furthermore, the dispersant may contain an acid-dissociable group. An acid-dissociable group is a group that generates an acidic group, such as a carboxyl group or a phenolic hydroxyl group, upon the action of an acid. 【0053】 Examples of acid-dissociable groups include groups having a t-butoxy structure and groups having an acetal structure. The acid that acts on the acid-dissociable groups is generated by an acid generator that produces acid through the action of light or heat. Therefore, the dispersion contains an acid generator together with a dispersant that has acid-dissociable groups. 【0054】 The conductive film formed on the organic material layer can be formed through the following process. 【0055】 As a method for coating the composition containing CNTs, appropriate methods such as spray coating, roll coating, rotary coating (spin coating), slit die coating (slit coating), bar coating (bar coating), solution immersion, and inkjet can be employed. The conductive film is formed to a certain thickness by a predetermined method. 【0056】 The composition containing CNTs that is applied to the organic material layer preferably has a dispersant content in the range of 1,000% to 100,000% by mass relative to the CNTs. Having the dispersant content within this range prevents non-uniformity of the solvent during the drying process and suppresses the aggregation and localization of CNTs during drying. 【0057】 Furthermore, to improve the purity of the conductive film, it is preferable to perform a baking process to remove the solvent and a solution immersion process to remove the dispersant. Among the coating methods described above, the slit die coating method or the inkjet method is preferred from the viewpoint of uniformity of the coating film thickness and liquid saving. Moreover, the inkjet method is more preferable from the viewpoint that electrode patterning can be performed by coating alone. 【0058】 By employing the conductive film formation method described above, the conductive film formed on the organic resin layer exhibits unique electrical properties, excellent adhesion to the organic resin layer, and good chemical resistance and flatness. 【0059】 Furthermore, because the CNTs contained in the coating film exhibit high adhesion to the organic resin layer, localization due to solvent aggregation during the drying process is suppressed. In addition, even during the solution immersion process for dispersant removal, peeling and aggregation of CNTs do not occur, thus suppressing localization of CNTs. Therefore, even when forming wiring with a very narrow pattern width, localized high-resistance areas and disconnections are less likely to occur. 【0060】 The method for manufacturing a conductive film according to this embodiment includes forming an insulating layer on a substrate, forming an organic resin layer after forming the insulating layer, and forming a conductive film made of CNTs on the organic resin layer. 【0061】 Furthermore, it is preferable that the CNTs contained in the dispersion include at least one of single-walled nanotubes or multi-walled nanotubes. According to this method for manufacturing conductive films, it is possible to form semiconductor devices with even better adhesion between the organic resin layer and the conductive film. Additionally, the manufacturing yield is further improved. 【0062】 Furthermore, the above-described method for manufacturing conductive films can be applied not only to the manufacture of display panels 1, but also to the manufacture of transparent conductive films used in touch panels. 【0063】 The organic resin layer can be formed by using a radiation-sensitive composite composition for forming the organic resin layer through the following steps. The organic resin layer formed by this method exhibits unique electrical properties, excellent adhesion to CNTs, and good chemical resistance and flatness. Furthermore, since heating is performed at 140°C or below using this method, thermal degradation of the substrate and the elements attached to the substrate is suppressed. Each step is described in detail below. 【0064】 [Process (1)] In this process, a coating film is formed on the insulating layer using the radiation-sensitive composition. Specifically, a coating film of the radiation-sensitive composition is formed by applying the radiation-sensitive composition to the surface of the insulating layer. It is preferable to perform a pre-bake treatment in this step to remove the solvent contained in the coating film. 【0065】 As a method for applying the radiation-sensitive composition, appropriate methods such as spraying, roll coating, rotary coating (spin coating), slit die coating, bar coating, and inkjet coating can be used. Among these, the inkjet coating method is preferred. The pre-baking conditions vary depending on the type and proportion of each component, but can be, for example, 60°C to 130°C for 30 seconds to 10 minutes. The film thickness of the formed coating after pre-baking is preferably 0.1 μm to 5 μm, more preferably 0.1 μm to 1 μm, and even more preferably 0.2 μm to 0.4 μm. 【0066】 [Process (2)] In this process, a portion of the coating film is irradiated (exposed) with radiation. Specifically, the coating film formed in process (1) is irradiated with radiation through a mask having a predetermined pattern. Depending on the pattern of the mask used, it is possible to form patterns such as contact holes or lines and spaces. 【0067】 Examples of radiation used in this process include ultraviolet rays, far-ultraviolet rays, X-rays, and charged particle beams. The mask used may also be a multi-tone mask such as a halftone mask or a graytone mask. 【0068】 Examples of ultraviolet light include g-rays (wavelength 436 nm), i-rays (wavelength 365 nm), and KrF excimer laser light (wavelength 248 nm). Examples of X-rays include synchrotron radiation. Examples of charged particle beams include electron beams. Of these radiations, ultraviolet light is preferred, and ultraviolet light with a wavelength of 200 nm to 380 nm is more preferred. The radiation exposure dose is 1,000 J / m². 2~20,000 J / m 2 It is preferable. 【0069】 In some cases, post-exposure baking (PEB) can also be performed after exposure. 【0070】 [Process (3)] In this step, the irradiated coating is developed. Specifically, the irradiated coating from step (2) is developed using a developer to remove the irradiated areas. As the developer, for example, an alkaline aqueous solution in which potassium hydroxide, sodium carbonate, triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc. are dissolved in water, or an organic solvent such as ethanol, isopropyl alcohol, acetone, ethyl acetate, or butyl acetate can be used. 【0071】 As for the development method, appropriate methods such as the liquid-filling method, dipping method, agitation immersion method, and shower method can be employed. The development time varies depending on the composition of the radiation-sensitive composition, but can be, for example, 30 to 120 seconds. 【0072】 [Process (4)] In this process, the coating film after step (3) above can be heated. The coating film is hardened by heat treatment (post-bake) using a heating device such as a hot plate or oven. 【0073】 The upper limit of the heating temperature in this process is 140°C, but the heating temperature may also be 130°C, 125°C, or 115°C. According to this forming method, the coating film can be formed into a good shape even with relatively low heating temperatures. 【0074】 [Example of combination] We conducted verification and evaluation experiments to confirm whether CNTs coated on a substrate adhere evenly and firmly to the conductive film formation region using an organic resin film containing a polymer consisting of an acid anhydride and a diamine having a heterocyclic structure according to the present invention, and these experiments are described below. 【0075】 Organic resin film containing a polymer composed of an acid anhydride and a diamine having a heterocyclic structure. <Synthesis of Diamines> DA-5 was synthesized using the method described in Journal of the American Chemical Society 2020, 142, 9752-9762. 【0076】 DA-1 used Tokyo Chemical Industry's B2169, DA-2 used Tokyo Chemical Industry's A3300, DA-3 used Sigma-Aldrich's 732079, and DA-4 used Tokyo Chemical Industry's A2759. <Synthesis of polymers> 1. Synthesis of polyamic acids [Synthesis Example 1] [ka] 【0077】 100 moles of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (TA-1) as a tetracarboxylic dianhydride and 100 moles of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole as a diamine compound were dissolved in N-methyl-2-pyrrolidone (NMP), and the reaction was carried out at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamic acid. Further dilution was performed so that the ratio of NMP to butyl cellosolve was 8:2 to obtain a 5% by mass solution of polyamic acid (this was designated as polymer (PA-1)). 【0078】 [Synthesis Examples 2-10, Comparative Synthesis Examples 1-4] The same procedure as in Synthesis Example 1 was followed, except that the types of tetracarboxylic dianhydride and diamine compounds used were changed as shown in Table 1, to obtain polyamic acid solutions (polymers (PA-2) to (PA-14)). PA-11, PA-12, PA-13, and PA-14 obtained in Comparative Synthesis Examples 1 to 4 are polyamic acids that do not have a heterocyclic structure. 【0079】 [Table 1] 【0080】 A solution (SL-1) with a total solids content of 2 wt% was prepared by mixing synthetic polymer PA-1 with N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane equivalent to 10 wt% of PA-1 and diluting with NMP. The same procedure was followed for PA-2 through PA-14 to prepare SL-2 through SL-14. 【0081】 1. Synthesis of polymers [Synthesis Example 1: Synthesis of Polyamic Acids] A polyamic acid having hydrocarbon groups in its side chains (hereinafter referred to as "polymer (paa-1)") was obtained by the synthesis method described in Patent Document 2 above. 【0082】 2. Preparation and evaluation of CNT-containing dispersion compositions (1) Preparation of dispersion composition 【0083】 10 parts by mass of single-walled carbon nanotubes (SWNT) and 1,000 parts by mass of polymer (paa-1) obtained in Synthesis Example 1 as a dispersant were placed in a container, to which 100,000 parts by mass of NMP was added as a solvent. Then, ultrasonic dispersion was performed for 60 minutes to prepare dispersion composition (S-1). 【0084】 (2) Formation of conductive film substrate SL-1 was applied to a glass substrate by spin coating (settings: 1500 rpm, rotation time: 20 seconds). Next, an organic resin film was formed by heating on a hot plate (100°C x 1 min) followed by heating and drying in an oven (200°C x 30 min). 【0085】 A CNT dispersion S-1 was applied to a glass substrate having an organic resin film by spin coating (set conditions: 500 revolutions / minute, rotation time: 30 seconds), and dried on an 80°C hot plate for 10 minutes to form a laminated coating consisting of the organic resin film and a mixed film of CNTs and a dispersant. The thickness of this laminated coating was 0.1 μm in the center of the glass substrate. 【0086】 A glass substrate was immersed in a petri dish filled with a 5 wt% sodium hydroxide aqueous solution for 1 minute to extract and remove the dispersant from the laminated coating. The glass substrate was then removed and air-blown to remove any remaining liquid, and dried on a 110°C hot plate for 1 minute to obtain a conductive film substrate in which only carbon nanotubes (CNTs) were present on the organic resin film. 【0087】 (3) Evaluation of CNT uniformity The dispersion composition (S-1) obtained in (1) above was applied by spin coating onto an organic resin layer formed from organic resin film solutions (SL-1) to (SL-14), and dried on a hot plate at 80°C for 10 minutes to form a coating film with a thickness of 0.1 μm in the center of the substrate. This coating film was observed with a microscope at 50x magnification to check for the presence or absence of areas where CNTs were aggregated. The evaluation was as follows: "Excellent (A)" if no areas of CNT aggregation were observed in the coating film, "Good (B)" if a small area of ​​CNT aggregation was observed, and "Poor (C)" if areas of CNT aggregation were clearly observed. The results are shown in Table 2 below. 【0088】 (4) Evaluation of CNT adhesion properties on organic resin film The surface resistivity (Ω / □) of the obtained CNT film was measured using a Loresta-GP (manufactured by Mitsubishi Chemical Analytics). 【0089】 When a large amount of CNTs are fixed onto the organic resin film, the surface resistivity value becomes smaller, 10 5 If the value is less than or equal to Ω / □, it is marked with "〇". 6 Ω / □ to 10 7 If the value of Ω / □ is shown, it is marked with "△", and if no value is obtained because it falls outside the measurable range of the Loresta-GP, it is marked with (10 8 Resistance values ​​greater than Ω / □ were marked with "×". The results are shown in Table 2 below. 【0090】 (5) Overall Judgment The overall assessment was based on whether CNT uniformity was "Poor (C)" or CNT adhesion was "×", in which case it was judged as NG; in all other cases, it was judged as OK. 【0091】 [Table 2] 【0092】 Comparative Examples 1 to 4 used polyamic acids PA-11, PA-12, PA-13, and PA-14 that did not have a heterocyclic structure. Examples 1 to 10 used polyamic acids that had a heterocyclic structure. Compared to Comparative Examples 1 to 4, it was found that the CNT uniformity and CNT adhesion properties were better in Examples 1 to 10. [Explanation of symbols] 【0093】 1: Display panel 2: Base material 2a: Element area 2b: Peripheral area 10: Insulating layer 20: Organic resin layer 30: Coating film 40: Conductive film

Claims

[Claim 1] Step (A) involves applying an organic resin material containing a polymer obtained by reacting an acid anhydride with an aromatic diamine containing a heterocyclic structure onto a substrate to form an organic resin layer. After performing step (A), step (B) is performed, in which a dispersion containing a dispersant and carbon nanotubes is applied to the organic resin layer to form a coating film. After performing step (B), step (C) is performed to dry the coating film, A method for manufacturing a conductive film, comprising the step (D) of applying a dispersant extract solution after performing the above step (C) to remove the dispersant from the coated film. [Claim 2] The method for manufacturing a conductive film according to claim 1, wherein step (D) is a step of removing the dispersant from the coated film by immersing the substrate in the dispersant extract. [Claim 3] The method for producing a conductive film according to claim 2, wherein step (D) is immersion in the dispersant extract, which consists of an alkaline aqueous solution. [Claim 4] The method for producing a conductive film according to claim 1, wherein the polymer has a moiety derived from an aromatic diamine having at least one heterocyclic structure selected from the following formulas (1), (2), and (3). 【Chemistry 1】 In equations (1) to (3), X represents O, S, or N. When X is O or S, n is 0, and when X is N, n is 1. Y is any organic group. R is a monovalent organic group and may or may not form a ring, and m is a number from 1 to 4. p, q, and r are 0 or numbers greater than or equal to 1, and the numbers of p, q, and r may be the same or different. [Claim 5] The method for producing a conductive film according to claim 1, wherein step (B) involves applying the dispersant containing an alkali-soluble polymer having one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and a phenolic hydroxyl group. [Claim 6] The method for producing a conductive film according to claim 1, wherein step (B) is to apply the dispersion containing the dispersant having a polymer having a polyamic acid structure and an organic solvent onto the organic resin layer. [Claim 7] The method for producing a conductive film according to claim 1, wherein step (B) is to apply the dispersion liquid having a dispersant content relative to the carbon nanotubes in the range of 1,000% by mass to 100,000% by mass. [Claim 8] A touch panel comprising a conductive film manufactured by the manufacturing method described in any one of claims 1 to 7. [Claim 9] A display panel comprising a conductive film manufactured by the manufacturing method described in any one of claims 1 to 7.

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