WO2023238530A1

WO2023238530A1 - Method for producing electroconductive film, touch panel, display panel

Info

Publication number: WO2023238530A1
Application number: PCT/JP2023/016108
Authority: WO
Inventors: 宏充勝井; 博幸安田
Original assignee: Jsr株式会社
Priority date: 2022-06-09
Filing date: 2023-04-24
Publication date: 2023-12-14
Also published as: TW202348547A

Abstract

Provided is a method for producing an electroconductive film that has high electroconductivity and is capable of evenly fixing an electroconductive carbon material over the entirety of an electroconductive film formation region.　The method includes a step (A) for applying an organic resin material that contains a polymer having a hydrocarbon group to a base material and forming an organic resin layer, a step (B) for applying a liquid dispersion that contains a dispersant and carbon nanotubes to the organic resin layer and forming a coating film after step (A), a step (C) for drying the coating film after step (B), and a step (D) for implementing dispersant extraction to remove the dispersant from the coating film after step (C).

Description

Manufacturing method of conductive film, touch panel, display panel

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.

In recent years, semiconductor devices in which electrodes and wiring are formed using conductive films made of nanocarbon materials have been developed. Conventionally, electrodes and wiring 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 made much thinner than metals or metal oxide films, and exhibit high conductivity, so they can be used as materials for semiconductor devices. is attracting a lot of attention. Furthermore, since conductive films made of nanocarbon materials can be formed into films that exhibit high transparency to visible light, there is a movement toward their active use in semiconductor optical devices.

From the above-mentioned background, various proposals have been made regarding materials and manufacturing methods, especially for conductive films made of CNTs. For example, Patent Document 1 listed below describes a composition in which a solvent and CNTs are used as a composition with improved dispersibility of CNTs. Compositions containing the present invention are disclosed.

Japanese Patent Application Publication No. 2010-214837

However, the conductive film produced using the above composition has a problem in that it tends to aggregate during the drying process and the like, and its homogeneity tends to be impaired. A CNT transparent conductive film exhibits conductivity by forming a circuit through which current flows by folding fibrous CNTs like a nonwoven fabric. For this reason, unlike metal films and metal oxide films, it has been difficult to configure them to have stable characteristics, and it has been difficult to develop stable electrical characteristics.

In particular, in semiconductor devices such as LSIs, which are becoming increasingly miniaturized, the wiring width is extremely narrow, so forming wiring with a CNT conductive film may result in partially high-resistance wiring or disconnection. The problem was that it was easy for this to occur.

In addition, when used in light emitting devices, touch panels, etc., it is required to form a conductive film as thin as possible in order to increase the transparency of visible light, and it is also required to form a conductive film with high conductivity and uniformity. be done. Even in such a case, a problem arises in that the conductive film is likely to be disconnected, similar to the above-mentioned semiconductor devices such as LSIs. More specifically, for example, when configuring wiring constituting a touch panel, wiring is formed with a width of 50 μm or less, or when creating a pixel electrode of a display panel, a lead line from a contact hole with a width of 50 μm or less is created. In some cases, wire breakage is particularly likely to occur.

In view of the above problems, an object of the present invention is to provide a method for manufacturing a conductive film that has high conductivity and can evenly fix a conductive carbon material over the entire conductive film formation area.

The method for manufacturing a conductive film of the present invention includes:
a step (A) of applying an organic resin material containing a polymer having a hydrocarbon group onto a base material to form an organic resin layer;
After carrying out the step (A), a step (B) of applying a dispersion liquid containing a dispersant and carbon nanotubes on the organic resin layer to form a coating film;
After carrying out the step (B), a step (C) of drying the coating film;
After carrying out the step (C), the method includes a step (D) of attaching a dispersant extract and removing the dispersant from the coating film.

In the above manufacturing method,
The step (D) may be a step of forming the coating film by immersing the base material in a dispersant extract.

Furthermore, in the above manufacturing method, the step (D) may be a step of immersing the dispersant extract in the aqueous alkaline solution.

In the above manufacturing method,
The step (A) may be a step of applying the organic resin material containing an aromatic hydrocarbon onto the base material, and preferably the organic resin material containing a polycyclic aromatic hydrocarbon is applied onto the base material. This is a process of applying a resin material.

In the above manufacturing method,
The step (B) may be a step of applying the dispersant containing an alkali-soluble polymer having one kind of functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and a phenolic hydroxyl group.

In the above manufacturing method,
The step (B) may be a step of applying the dispersion containing the dispersant containing the polymer having a polyamic acid structure and an organic solvent onto the organic resin layer.

Note that the dispersant is preferably a polymer having a constituent part represented by the following formula (1).

(In formula (1), R ¹ is a tetravalent organic group that constitutes a tetracarboxylic acid, R ² is a divalent organic group that constitutes a diamine, and n represents a positive integer.)

Further, in the structural moiety represented by the above formula (1) that the dispersant has, R ¹ is preferably a cyclobutane ring.

In the above manufacturing method,
The step (B) is a step of applying the dispersion liquid in which the content of the dispersant to the carbon material is within the range of 1,000% by mass to 100,000% by mass on the organic resin layer. I don't mind.

In the above manufacturing method,
The step (B) may be a step of applying the dispersant to the organic material layer by any one of a spin coating method, a slit coating method, a bar coating method, a spray coating method, and an inkjet method. do not have.

The touch panel of the present invention includes:
A conductive film manufactured by the above manufacturing method is provided.

The display panel of the present invention includes:
A conductive film manufactured by the above manufacturing method is provided.

According to the present invention, a method for manufacturing a conductive film is realized that has high conductivity and can evenly fix a conductive carbon material over the entire conductive film formation region.

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of a display panel. 3 is a drawing schematically showing a process of forming a conductive film. 3 is a drawing schematically showing a process of forming a conductive film. 3 is a drawing schematically showing a process of forming a conductive film. This is an AFM photograph of the surface of the substrate. This is an AFM photograph of the surface of the substrate.

In the following, the configuration of the display panel 1 as one embodiment will be explained first, and then the details of one embodiment of the method for manufacturing the conductive film included in the display panel 1 will be explained. Then, a verification and evaluation experiment was conducted to confirm the effects of the present invention using an example of the method for manufacturing a conductive film of the present invention, and finally, the details of the verification and evaluation experiment will be explained.

[Display panel]
The overall configuration of an embodiment of the display panel 1 will be described. FIG. 1 is a schematic diagram showing the overall configuration of one embodiment of a display panel 1. As shown in FIG. 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.

The base material 2 is formed of a material having translucency, and specifically includes, for example, a glass substrate, a quartz substrate, or an organic resin substrate. Examples of the material for the organic resin substrate include polyimide. The organic resin substrate can have a thickness ranging from several micrometers to several tens of micrometers, making it possible to realize a flexible sheet display.

The element area 2a is an area where elements for displaying images are formed. In the element region 2a, a lower layer electrode is provided, and an insulating layer is provided on the lower layer electrode. An organic resin layer is provided on the insulating layer, and a conductive film is provided on the organic resin layer.

The material of the organic resin layer is an organic material containing a polymer having hydrocarbon groups. The material of the conductive film is CNT. As the type of CNT, single-walled carbon nanotubes or multi-walled carbon nanotubes having two or more layers can be employed, and single-walled carbon nanotubes are preferable.

A conductive film made of carbon nanotubes has a transmittance that varies depending on the film thickness, but is a transparent conductive film that is transparent to visible light.

The material constituting the organic resin layer is an organic resin material containing a polymer having a hydrocarbon group. Although not particularly limited, examples of the material constituting the organic resin layer include polyimide resin, polyamide resin, polyether resin, polyester resin, and the like. Note that, from the viewpoint of adhesion of carbon nanotubes, the material constituting the organic resin layer is preferably a material containing an aromatic hydrocarbon, and more preferably a material containing a polycyclic aromatic hydrocarbon.

The coating film is formed by applying a dispersion liquid containing carbon nanotubes and a dispersant. Although the dispersant is not particularly limited, it is preferable to use a polyamic acid having a structural moiety represented by formula (1) in terms of improving the dispersibility of carbon nanotubes. Just to be sure, equation (1) is reproduced.

Specific examples of the tetravalent organic group constituting the tetracarboxylic acid represented by ^R1 include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, and 1,2,5,6-naphthalenetetracarboxylic acid. Carboxylic 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-hexane Fluoro-2,2-bis(3,4-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl)dimethylsilane, bis(3,4-dicarboxyphenyl)diphenylsilane, 2,3,4, 5-pyridinetetracarboxylic acid, dianhydrides of aromatic tetracarboxylic acids such as 2,6-bis(3,4-dicarboxyphenyl)pyridine, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2 ,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 2,3,5-tricarboxycyclopentyl acetic acid, 3,4-dicarboxy-1,2,3,4- Examples include dianhydrides of tetracarboxylic acids having an alicyclic structure such as tetrahydro-1-naphthalenesuccinic acid, and dianhydrides of aliphatic tetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid. As these acid dianhydrides, a single compound may be used, or a plurality of compounds may be used in combination.

Specific examples of the divalent organic group constituting the diamine represented by ^R2 include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diamino Biphenyl, 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-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)diphenylsulfone, 2,2-bis[4-(4- Aromatic diamines such as aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, bis(4-aminophenoxy)phenyl]propane, -aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, cycloaliphatic diamines such as cholestanyl 3,5-diaminobenzoate, and 1,2-diaminoethane, 1,3-diaminopropane, 1, Examples include aliphatic diamines such as 4-diaminobutane and 1,6-diaminohexane, and silicone diamines such as 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. A single compound may be used as these diamines, or a plurality of compounds may be used in combination.

Further, it is preferable that R ¹ in the above formula (1) is a cyclobutane ring. When the cyclobutane ring is irradiated with light or heated, the ring structure decomposes and a structural change of the polyamic acid occurs, thereby making it possible to remove the dispersant. This is preferable in that it can be easily removed. Moreover, the above-mentioned dispersion liquid may contain an organic solvent as a dispersion medium.

[Production method]
A method for manufacturing a conductive film will be described with reference to FIGS. 2 to 4. 2 to 4 are drawings schematically showing the process of forming a conductive film. Note that in the method for manufacturing a conductive film of this embodiment, a conductive film is manufactured on an insulating layer formed on a substrate.

As shown in FIG. 2, an organic resin material containing a polymer having a hydrocarbon group is applied onto the base material 2 on which the insulating layer 10 has been formed to form an organic resin layer 20 (step (A)). ).

As shown in FIG. 3, a dispersion containing CNTs is applied onto the organic resin layer 20 to form a pattern of a coating film 30 (corresponding to step (B)). Note that in FIG. 3, for convenience, the coating film 30 is illustrated as being formed over the entire surface of the organic resin layer 20.

In this step, a pattern is formed by a coating film of a dispersion containing CNTs on the organic resin layer 20 using printing techniques such as casting, screen printing, and inkjet. After forming the pattern, as shown in FIG. 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 step (C)). .

In FIG. 4, for convenience, the conductive film 40 is illustrated as being formed over the entire surface of the organic resin layer 20, but the pattern of the conductive film 40 may be adjusted as appropriate.

After the solvent is removed by drying, a dispersant extract is applied onto the conductive film formed on the substrate, and the dispersant is removed from the pattern formed by the coated film (corresponding to step (D)). In addition, in this process, in addition to the above-mentioned method of forming a pattern by printing, in forming a pattern of a conductive film, a dispersion liquid is applied to the entire organic resin layer formed on the substrate, and then dried and washed. After this, it is also possible to separately form a photosensitive resist layer for patterning 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.

Note that the combination of the dispersant and the dispersant extract is arbitrary, but the dispersant is an alkali-soluble polymer having a functional group that improves solubility in an alkaline aqueous solution, and the dispersant extract is an alkaline aqueous solution. is preferred. By using an alkaline aqueous solution as a dispersant extract, it becomes possible to selectively leave CNTs that are difficult to disperse in an alkaline aqueous solution on the organic resin layer.

Additionally, by using a process that uses such an alkali-soluble polymer, it is possible to share the same materials with other processes that use photosensitive resist layers that also use an alkaline aqueous solution for development, greatly increasing productivity. .

Further, as the alkaline aqueous solution, for example, KOH (potassium hydroxide), NaOH (sodium hydroxide), sodium carbonate, TMAH (tetramethylammonium hydroxide) aqueous solution, etc. can be suitably used.

Furthermore, these dispersants may contain a molecular structure in the material that can react to light or heat and cause decomposition or structural change to improve solubility in an aqueous alkaline solution. Using such a dispersant, the solubility is improved by applying light or heat after forming a conductive film, and then a dispersant extract is applied, which further removes the dispersant from the pattern formed by the coated film. This makes it possible to improve efficiency.

As a molecular structure exhibiting such a function, for example, the polyamic acid structure of the dispersant may include a site such as cyclobutane that can be decomposed by light or heat to change the entire structure of the polyamic acid. Further, 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 by the action of an acid.

Examples of the acid-dissociable group include a group having a t-butoxy structure and a group having an acetal structure. The acid that acts on the acid-dissociable group is generated from an acid generator that generates acid under the action of light or heat. Therefore, an acid generator is contained in the dispersion together with a dispersant having an acid-dissociable group.

The conductive film formed on the organic material layer can be formed through the steps shown below.

Examples of methods for applying the composition containing CNTs include spray coating, roll coating, spin coating, slit die coating, bar coating, and solution coating. An appropriate method such as a dipping method or an inkjet method can be employed. The conductive film is formed with a constant thickness by a predetermined method.

In the composition containing CNTs that is coated on the organic material layer, the content of the dispersant relative to the CNTs is preferably within the range of 1,000% by mass to 100,000% by mass. When the content of the dispersant for the CNTs is within this range, non-uniformity of the solvent in the drying process is prevented, and aggregation and localization of the CNTs due to drying is suppressed.

Note that, in order to improve the purity of the conductive film, it is preferable that a process of removing the solvent by a baking process or a process of dipping in a solution for removing a dispersant is performed. Among the above-mentioned coating methods, the slit die coating method or the inkjet method is preferable from the viewpoint of uniformity of the coating film thickness and liquid saving. Further, from the viewpoint that electrode patterning can be performed only by coating, the inkjet method is more preferable.

By adopting the method for forming a conductive film described above, the conductive film formed on the organic resin layer exhibits unique electrical properties, has excellent adhesion to the organic resin layer, and has excellent chemical resistance and flatness. will also be good.

Furthermore, since the CNTs contained in the coating film exhibit high adhesion to the organic resin layer, localization due to aggregation of the solvent in the drying process is suppressed. Furthermore, even in the solution immersion step for removing the dispersant, peeling and aggregation of CNTs do not occur, and localization of CNTs is suppressed. Therefore, even if a wiring with a very narrow pattern width is formed, locally high resistance parts and disconnections are less likely to occur.

The method for manufacturing a conductive film of 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 CNT on the organic resin layer. include.

Furthermore, it is preferable that the CNTs contained in the dispersion liquid include at least one of single-walled nanotubes and multi-walled nanotubes. According to such a method of manufacturing a conductive film, it is possible to form a semiconductor device with even better adhesion between the organic resin layer and the conductive film. Moreover, the manufacturing yield becomes even better.

Furthermore, the method for manufacturing a conductive film described above can be applied not only to the manufacture of the display panel 1 but also to the manufacture of a transparent conductive film used in a touch panel.

Note that the organic resin layer can be formed by using the radiation-sensitive composition for forming the organic resin layer through the steps shown below. The organic resin layer formed by this formation method exhibits unique electrical properties, has excellent adhesion to CNTs, and has good chemical resistance and flatness. Further, according to the formation method, since heating is performed at 140° C. or lower, thermal deterioration of the substrate and elements provided on the substrate is suppressed. Each step will be explained in detail below.

[Step (1)]
In this step, 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. In addition, in order to remove the solvent contained in the coating film, it is preferable that a pre-baking treatment is performed in this step.

As a method for applying the radiation-sensitive composition, an appropriate method such as a spray method, a roll coating method, a spin coating method, a slit die coating method, a bar coating method, an inkjet method, etc. can be adopted. Among these, the inkjet method is preferred as the coating method. The prebaking conditions may vary depending on the type of each component, the proportion used, etc., but may be, for example, at 60° C. to 130° C. for about 30 seconds to 10 minutes. The thickness of the coating film formed after prebaking 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.

[Step (2)]
In this step, a portion of the coating film is irradiated (exposed) with radiation. Specifically, the coating film formed in step (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 hole formation and line and space formation.

Examples of the radiation used at this time include ultraviolet rays, deep ultraviolet rays, X-rays, and charged particle beams. Further, the mask used may be a multi-tone mask such as a halftone mask or a graytone mask.

Examples of the ultraviolet light include g-line (wavelength: 436 nm), i-line (wavelength: 365 nm), KrF excimer laser light (wavelength: 248 nm), and the like. Examples of the X-ray include synchrotron radiation. Examples of the charged particle beam include an electron beam. Among these radiations, ultraviolet rays are preferable, and ultraviolet rays with a wavelength of 200 nm or more and 380 nm or less are more preferable. The amount of radiation exposure is preferably 1,000 J/m ² to 20,000 J/m ² .

In some cases, post-exposure bake (PEB) can also be performed after exposure.

[Step (3)]
In this step, the coating film irradiated with radiation is developed. Specifically, the coating film irradiated with radiation in step (2) is developed with a developer to remove the radiation irradiated portion. Examples of the developer include an alkaline aqueous solution in which potassium hydroxide, sodium carbonate, triethanolamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc. are dissolved in water, ethanol, isopropyl alcohol, acetone, ethyl acetate, Organic solvents such as butyl acetate can be used.

As a developing method, an appropriate method such as a liquid piling method, a dipping method, a rocking immersion method, a shower method, etc. can be adopted, for example. The development time varies depending on the composition of the radiation-sensitive composition, but can be, for example, 30 seconds to 120 seconds.

[Step (4)]
In this step, the coating film after the above step (3) can be heated. The coating film is cured by heat treatment (post-baking) using a heating device such as a hot plate or an oven.

The upper limit of the heating temperature in this step is 140°C, and the heating temperature may be 130°C, 125°C, or 115°C. According to the formation method, the coating film can be formed into a good shape even by heating at a relatively low temperature.

[Verification evaluation experiment]
Finally, a verification and evaluation experiment was conducted to confirm the degree of effect obtained by the manufacturing method of the present invention regarding the dispersibility of CNTs contained in the dispersion liquid applied onto the substrate, which will be described below.

1. Synthesis of polymer [Synthesis example 1: Synthesis of polyamic acid]
A polyamic acid having a hydrocarbon group in its side chain (hereinafter referred to as "polymer (paa-1)") was obtained by the synthesis method described in Patent Document 2 above.

[Synthesis Example 2: Synthesis of polyamic acid]
A photodegradable polyamic acid having a hydrocarbon group in its side chain (hereinafter referred to as "polymer (paa-2)") was obtained by the synthesis method described in Patent Document 3 above.

[Comparative synthesis example 1: polyimide synthesis]
N-methyl-2-pyrrolidone (NMP) was added to a polyamic acid solution obtained in the same manner as in Synthesis Example 1 above. A predetermined imidizing agent was added to the above solution, heated at 110° C., and reacted for a predetermined time to obtain a polyimide (hereinafter referred to as "polymer (PI-1)"). The imidization rate of the obtained polymer (PI-1) was 50%.

2. Preparation and evaluation of CNT-containing dispersion composition (1) Preparation of dispersion composition 10 parts by mass of single wall carbon nanotubes (SWNT) and 50 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 as a dispersant were contained. 100,000 parts by mass of NMP was added as a solvent to the container. Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-1).

Next, 100,000 parts by mass of NMP was added as a solvent to a container containing 10 parts by mass of single-wall carbon nanotubes (SWNT) and 100 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 as a dispersant. . Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-2).

Next, 100,000 parts by mass of NMP was added as a solvent to a container containing 10 parts by mass of single-wall carbon nanotubes (SWNT) and 500 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 as a dispersant. . Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-3).

Next, 100,000 parts by mass of NMP was added as a solvent into a container containing 10 parts by mass of single-wall carbon nanotubes (SWNT) and 1,000 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 as a dispersant. added. Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-4).

Next, 100,000 parts by mass of NMP was added as a solvent into a container containing 10 parts by mass of single-wall carbon nanotubes (SWNT) and 5,000 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 as a dispersant. added. Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-5).

Next, 100,000 parts by mass of NMP was added as a solvent to a container containing 10 parts by mass of single-wall carbon nanotubes (SWNT) and 500 parts by mass of the polymer (PAA-2) obtained in Synthesis Example 2 as a dispersant. . Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (S-6).

Next, 100,000 parts by mass of NMP was added as a solvent to a container containing 10 parts by mass of single-wall carbon nanotubes (SWNT) and 500 parts by mass of the polymer (PI-1) obtained in Comparative Synthesis Example 1 as a dispersant. Ta. Next, ultrasonic dispersion was performed for 60 minutes to prepare a dispersion composition (C-1).

(2) Evaluation of CNT dispersibility The dispersion compositions (S-1) to (C-1) obtained in (1) above were allowed to stand on a flat place in an environment of 25°C. The evaluation is "Excellent (A)" if the CNTs maintain their initial dispersion state without settling after one week, and "Excellent (A)" if the CNTs maintain their initial dispersion state without settling after three days. (B)", "Good (C)" if the CNTs maintain their initial dispersion state without settling for up to 1 day; "Good (C)" indicates that the CNTs maintain their initial dispersion state without settling until 3 hours later. If sedimentation or aggregation of CNTs was observed within 3 hours, it was rated as "Poor (E)." As a result, the CNT dispersibility of the dispersion compositions (S-1) to (S-6) and (C-1) was "excellent (A)".

(3) Evaluation of CNT dispersion stability (durability) A dispersion composition was prepared in the same manner as in (1) above. The obtained dispersion composition was left standing on a flat place in an environment of 40°C, and the state of dispersion over time was observed. The evaluation is "Excellent (A)" if the CNTs do not settle and maintain the initial dispersion state after one week, and if the CNTs do not settle and maintain the initial dispersion state after 3 days. "Excellent (B)", if the CNTs do not settle and maintain the initial dispersion state until 1 day later, "Good (C)", if the CNTs do not settle and maintain the initial dispersion state until 3 hours later. If the temperature was maintained, it was rated as "fair (D)", and if sedimentation or aggregation was observed after 3 hours, it was rated as "poor (E)". As a result, the CNT dispersion stability of the dispersion compositions (S-1) to (S-6) and (C-1) was "excellent (A)".

(4) Evaluation of CNT (carbon nanotube) applicability The dispersion compositions (S-1) to (C-1) obtained in (1) above were applied by spin coating onto a glass substrate on which an organic resin layer was formed. Then, by drying on a hot plate at 80° C. for 10 minutes, a coating film having a thickness of 0.1 μm at the center of the substrate was formed. This coating film was observed under a microscope with a magnification of 50 times to check for uneven thickness of the coating film and the presence or absence of pinholes. In the evaluation, the coating property was rated "Excellent (A)" when neither film thickness unevenness nor pinholes were observed, and the coating property was rated "Good (A)" when at least one of film thickness unevenness and pinholes was slightly observed. B). When at least one of film thickness unevenness and pinholes was clearly observed, the coating property was evaluated as "poor (C)". As a result, in (S-3) to (S-5) and (C-1), neither film thickness unevenness nor pinholes were observed, and the coating properties were "excellent (A)". In (S-1) and (S-2), slight unevenness in film thickness was observed, and the coating properties were "good (B)".

(5) Evaluation of dispersant removability The dispersion compositions (S-1) to (C-1) obtained in (1) above were applied by spin coating onto a glass substrate on which an organic resin layer was formed. By drying for 10 minutes on a hot plate at .degree. C., a coating film having a thickness of 0.1 .mu.m at the center of the substrate was formed. Regarding (S-6), the coating film was irradiated with 1 J of ultraviolet light having a wavelength of 260 nm using a UV lamp. This coating film was immersed in an aqueous sodium hydroxide solution for 1 minute, and the surface was observed using an AFM (atomic force microscope, manufactured by Hitachi High-Technology).

5 and 6 are both photographs taken using AFM of the surface of the substrate. FIG. 5 is an example of a photograph of the substrate surface where the unevenness of CNTs is observed, and FIG. This is an example of a photograph of a substrate surface that is not observed by AFM, that is, CNTs are covered with a resin/dispersant. If the dispersant on the surface has been removed and CNTs (carbon nanotubes) are exposed as shown in Figure 5, it is rated as "Good (A)", and as shown in Figure 6, CNTs are partially exposed. A sample was rated as "fair (B)", and a sample where the surface was covered with resin and no exposed CNTs were observed, or the film formation was poor and could not be determined was graded as "poor (C)".

As a result, in (S-2) to (S-4) and (S-6), the dispersant on the surface was removed and CNTs (carbon nanotubes) were exposed, so the judgment was "Good (A)". did. In (S-1), although CNTs were exposed, aggregation of CNTs was observed, so the evaluation was "fair (B)". In (S-5), although the CNTs were exposed, some of the CNT surfaces were covered with resin, and the evaluation was "fair (B)". In (C-1), the surface was covered with the dispersant and no exposed CNTs were observed, so it was rated as "Poor (C)".

The above results are summarized as shown in Table 1 below.

1: Display panel 2: Base material 2a: Element region 2b: Peripheral region 10: Insulating layer 20: Organic resin layer 30: Coating film 40: Conductive film

Claims

A step (A) of applying an organic resin material containing a polymer having a hydrocarbon group onto the base material to form an organic resin layer;
After carrying out the step (A), a step (B) of applying a dispersion liquid containing a dispersant and carbon nanotubes on the organic resin layer to form a coating film;
After carrying out the step (B), a step (C) of drying the coating film;
A method for manufacturing a conductive film, which includes a step (D) of attaching a dispersant extract and removing the dispersant from the coated film after carrying out the step (C).
The method for manufacturing a conductive film according to claim 1, wherein in the step (D), the coating film is formed by immersing the base material in a dispersant extract.
The method for producing a conductive film according to claim 2, wherein the step (D) includes immersion in the dispersant extract consisting of an alkaline aqueous solution.
The method for producing a conductive film according to any one of claims 1 to 3, wherein in the step (A), the organic resin material containing an aromatic hydrocarbon is applied onto the base material.
The method for manufacturing a conductive film according to claim 4, wherein in the step (A), the organic resin material containing a polycyclic aromatic hydrocarbon is applied onto the base material.
6. The step (B) comprises applying the dispersant containing an alkali-soluble polymer having one type of functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and a phenolic hydroxyl group. A method for producing a conductive film according to.
According to any one of claims 1 to 6, in the step (B), the dispersion containing the dispersant containing a polymer having a polyamic acid structure and an organic solvent is applied onto the organic resin layer. The method for manufacturing the conductive film described above.
1. The step (B) comprises applying the dispersion liquid on the organic resin layer in which the content of the dispersant relative to the carbon nanotubes is within the range of 1,000% by mass to 100,000% by mass. 8. The method for producing a conductive film according to any one of items 7 to 7.
A touch panel comprising a conductive film manufactured by the manufacturing method according to any one of claims 1 to 8.
A display panel comprising a conductive film manufactured by the manufacturing method according to any one of claims 1 to 8.