Method for producing organic conductive film, organic conductive film, and laminate

Abstract

A method for producing an organic conductive film, comprising: a step of preparing a coating liquid containing an acid-based organic conductive polymer, an alkali neutralizing agent, and a liquid medium, and having a pH of 4.0 to 6.5 at 25°C; a step of applying the coating liquid to a substrate layer; and a step of removing the liquid medium from the applied coating liquid.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing an organic conductive film, an organic conductive film, and a laminate. BACKGROUND

[0002] In recent years, liquid crystal display devices, electroluminescent displays, solar cells, touch panels, and the like have been widely spread, and among these, an electrode in which ITO (indium tin oxide) is layered on a film is used as a transparent electrode. However, there are concerns about worldwide resource depletion and safety of indium as a material of ITO, and research is being conducted on organic materials as a substitute. As such organic materials, π-conjugated conductive polymers can be cited, and specifically, polythiophene-based conductive polymers can be cited.

[0003] As for a technique for forming a π-conjugated conductive polymer film, it is known to use a conductive polymer solution containing a π-conjugated conductive polymer (for example, refer to Patent Literature 1).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 7-105718 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the case of preparing a solution according to Patent Literature 1, a solution containing an acid-based organic conductive polymer sometimes exhibits strong acidity due to its composition. In this case, from the viewpoints of safety assurance and corrosion inhibition of a processing device, and the like, it is considered to adjust the pH of the solution to the vicinity of neutral using a neutralizing agent or the like. However, according to the present inventors' insight, the light resistance of a conductive polymer layer formed using a solution whose pH is thus adjusted is insufficient.

[0009] The present disclosure was completed in view of the above circumstances, and aims to provide a method for manufacturing an organic conductive film excellent in light resistance. Another object of the present disclosure is to provide an organic conductive film excellent in light resistance.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] As a result of intensive studies by the present inventors, it was revealed that the amount of components from an alkali neutralizing agent remaining in a conductive layer formed from a solution containing an acid-based organic conductive polymer has an influence on light resistance. Under this insight, the present inventors finally completed the present invention.

[0012] One aspect of this disclosure relates to a method for manufacturing an organic conductive film, comprising: a step of preparing a coating solution containing an acidic organic conductive polymer, an alkali neutralizer, and a liquid medium, and having a pH of 4.0 to 6.5 at 25°C; a step of coating the coating solution onto a substrate layer; and a step of removing the liquid medium from the coated coating solution. By using a coating solution with such pH adjusted, as described later, the cation content from the alkali neutralizer in the acidic organic conductive polymer layer can be appropriately controlled, resulting in the manufacture of an organic conductive film with excellent lightfastness. According to the inventors' research, it is important that, in addition to ensuring the pH is not too high (i.e., the cation content from the alkali neutralizer is not excessive), the pH is also not too low (i.e., the cation content from the alkali neutralizer is not too low).

[0013] In one manufacturing method, the acid-based organic conductive polymer may include a polythiophene-based conductive polymer.

[0014] In one manufacturing method, the alkali neutralizing agent may include ammonia.

[0015] One aspect of this disclosure relates to an organic conductive film comprising a substrate layer and an acid-based organic conductive polymer layer on the substrate layer, wherein the acid-based organic conductive polymer layer contains 0.5–5.0 mg / cm³ of cations derived from an alkali neutralizing agent. 3 The content of cations from the alkali neutralizing agent in the acidic organic conductive polymer layer was set at 0.5–5.0 mg / cm³. 3 Within this range, organic conductive films with excellent light resistance can be obtained.

[0016] In one type of organic conductive film, the acid-based organic conductive polymer may include a polythiophene-based conductive polymer.

[0017] In one type of organic conductive film, the cations from the base neutralizer may include ammonium ions.

[0018] In one type of organic conductive film, the substrate layer may comprise a resin substrate or a glass substrate.

[0019] In one approach, organic conductive films can be used as resistive coatings for electromagnetic wave suppression sheets or as circuit materials in electronic devices.

[0020] Effects of the present invention

[0021] According to this disclosure, a method for manufacturing an organic conductive film with excellent lightfastness can be provided. Furthermore, according to this disclosure, an organic conductive film with excellent lightfastness can be provided. Such an organic conductive film can be obtained by the above-described manufacturing method. Attached Figure Description

[0022] [ Figure 1 ] Figure 1A schematic cross-sectional view of an organic conductive film to which an embodiment relates. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present application will be described in detail. However, the present application is not limited to the following embodiments.

[0024] <Organic conductive film>

[0025] Figure 1 A schematic cross-sectional view of an organic conductive film to which an embodiment relates. The organic conductive film 10 has a substrate layer 1 and an acid-based organic conductive polymer layer 2 on the substrate layer 1.

[0026] (Substrate layer)

[0027] The substrate layer functions as a substrate of the organic conductive film. As a material of the substrate layer, resins and glasses can be listed. That is, the substrate layer can include a resin substrate or a glass substrate, or can be a resin substrate or a glass substrate.

[0028] As the resin, there is no particular limitation, and for example, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, modified polyesters, and the like; polyolefin resins such as polyethylene (PE) resin, polypropylene (PP) resin, cyclic olefin resin, and the like; vinyl-based resins such as polyvinyl chloride, polyvinylidene chloride, and the like; polyvinyl acetal resins such as polyvinyl butyral (PVB) and the like; polyether ether ketone (PEEK) resin; polysulfone (PSF) resin; polyether sulfone (PES) resin; polycarbonate (PC) resin; polyamide resin; polyimide resin; polystyrene resin; acrylic resin; triacetyl cellulose (TAC) resin, and the like can be listed. From the viewpoints of availability, price, and the like, the resin can be a polyester resin such as PET or PBT, or a polyolefin resin such as PP.

[0029] As the glass, there is no particular limitation, and for example, soda-lime glass, lead glass, borosilicate glass, quartz glass, and the like can be listed. From the viewpoints of availability, price, and the like, the glass can be soda-lime glass.

[0030] The substrate layer can include one layer formed of these materials, or can include multiple layers. In the case where the substrate layer is composed of multiple layers (is a laminate), resin substrates can be used in combination with each other, or a resin substrate and a glass substrate can be used in combination. As the combination of resin substrates with each other, for example, a PP layer / PET layer composition, a PP layer / PBT layer composition can be listed.

[0031] The thickness of the base material layer is not particularly limited, but can be, for example, 10 to 200 μm, or 25 to 75 μm, from the viewpoint of transparency and strength according to the use. In addition, from the viewpoint of coatability of the coating liquid, adhesion to the polymer layer, and the like, the surface of the base material layer can be subjected to a corona treatment or an easy-adhesion treatment as needed.

[0032] The base material layer can be permeable or impermeable to electromagnetic waves in the visible light region, and is appropriately selected according to the specifications of the organic conductive film. For example, in the case where the organic conductive film is required to be permeable to electromagnetic waves in the visible light region, a permeable base material layer can be selected. In addition, in the case where the base material is required to have a pattern or a wood grain design, printing can be performed on the base material layer or a concave-convex structure can be formed on the surface of the base material layer.

[0033] (Acid-based organic conductive polymer layer)

[0034] The acid-based organic conductive polymer layer has conductivity and contains an acid-based organic conductive polymer. In the present specification, the acid-based organic conductive polymer refers to a conductive complex containing a π-conjugated conductive polymer and a polyanion dopant with respect to the π-conjugated conductive polymer. As the π-conjugated conductive polymer, there is no particular limitation, and polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylene vinylene, polynaphthalene, and derivatives thereof, and the like can be exemplified. Among these, the π-conjugated conductive polymer can be particularly a polythiophene-based conductive polymer from the viewpoint of transparency, conductivity, stability, and the like.

[0035] As the polythiophene-based conductive polymer, for example, polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), poly(3-iodothiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxythiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-didodecyloxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4-carboxybutylthiophene) can be exemplified. From the viewpoints of conductivity, chemical stability, productivity, and the like, the polythiophene-based conductive polymer can be poly(3,4-ethylenedioxythiophene).

[0036] The polythiophene-based conductive polymer can be used alone or in combination of two or more.

[0037] The acid-based organic conductive polymer layer contains a polyanionic dopant with respect to the π-conjugated conductive polymer. Thereby, the conductivity of the acid-based organic conductive polymer layer can be improved. As the polyanionic dopant, for example, a polymer acid having a sulfonic group such as alkane sulfonic acid, polystyrene sulfonic acid, polyvinyl sulfuric acid, polyvinyl sulfonic acid, polyaryl sulfonic acid, polypropylene sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamide-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, poly(sulfonethyl methacrylate), poly(sulfobutyl methacrylate), poly(methacryloyloxybenzenesulfonic acid), and the like; an organic acid having a sulfonic group such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, and the like can be exemplified. From the viewpoints of chemical stability and conductivity, the polyanionic dopant can be polystyrene sulfonic acid.

[0038] The polyanion dopant can be used alone or in combination of two or more.

[0039] At least a part of the polythiophene-based conductive polymer and at least a part of the polyanion dopant form a conductive complex within the layer. From the viewpoints of transparency, conductivity, and the like, the conductive complex can be a complex of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrenesulfonic acid (PSS), i.e., poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT-PSS).

[0040] The acid-based organic conductive polymer layer can also contain other components (e.g., a binder and the like) other than the polythiophene-based conductive polymer and the polyanion dopant, provided that the intended effects are not significantly impaired. In this case, the total amount of the polythiophene-based conductive polymer and the polyanion dopant in the acid-based organic conductive polymer layer can be 50% by mass or more, can be 80% by mass or more, or can be 90% by mass or more.

[0041] The thickness of the acid-based organic conductive polymer layer is not particularly limited and can be, for example, 10 nm to 1 μm, or can be 200 to 600 nm.

[0042] As described later, the acid-based organic conductive polymer layer can be formed by applying a coating liquid containing an acid-based organic conductive polymer and a base neutralizer and having a pH of 4.0 to 6.5 at 25°C onto the base layer. From the viewpoint of maintaining excellent light resistance, the content of cations from the base neutralizer in the acid-based organic conductive polymer layer can be 0.5 to 5.0 mg / cm 3 , can be 3.0 to 5.0 mg / cm 3 , or can be 4.5 to 5.0 mg / cm 3 It is presumed that the acid-based organic conductive polymer layer contains a certain amount or more of cations because the cations are trapped due to the formation of hydrogen bonds or the like with the acid-based organic conductive polymer and remain in the layer after the removal of the liquid medium.

[0043] The content of cations can be measured by ion chromatography. Specifically, the organic conductive film is placed in an extraction solvent (ultrapure water) and left to stand for 24 hours in an environment of 25°C. The extraction solvent after the standing is diluted 50 times with ultrapure water, and the cations are quantified by ion chromatography. From the quantification results, the content of the cations remaining in the acid-based organic conductive polymer layer can be calculated.

[0044] The cations from the base neutralizer can include ammonium ions. In this case, the amount of the ammonium ions present in the acid-based organic conductive polymer layer can be 0.5 to 5.0 mg / cm 3, can be 3.0 to 5.0 mg / cm 3 , can be 4.5 to 5.0 mg / cm 3 .

[0045] The acid-based organic conductive polymer layer is excellent in light resistance, which means that the surface resistance is difficult to increase with time. In a measurement using a 4-terminal method, the change in surface resistance of the acid-based organic conductive polymer layer represented by the following formula can be 4.0 x 10 2 or less, and 2 or less.

[0046] Surface resistance change = surface resistance value after light resistance test / surface resistance value before light resistance test

[0047] Here, the light resistance test refers to a xenon type accelerated light resistance test (conditions: irradiation intensity 60 W / m 2 , BPT temperature 63°C, tank temperature 40°C, tank humidity 50% rh, test time 500 hours).

[0048] The organic conductive film can be used as a resistance coating film of an electromagnetic wave suppression sheet or a circuit material in an electronic device, but is not limited thereto. Note that, as an electromagnetic wave suppression sheet, the organic conductive film can be used as a resistance coating layer as described in Japanese Patent No. 6523563. In addition, as an electronic device, the organic conductive film can be used as a hole transport layer as described in Japanese Laid-Open Patent Publication No. 2005-71929.

[0049] < Electromagnetic wave suppression sheet >

[0050] The electromagnetic wave suppression sheet can be considered as a laminate having an organic conductive film, a dielectric layer, and an electromagnetic wave shielding layer. The method for manufacturing the electromagnetic wave suppression sheet is not particularly limited, and the following methods can be exemplified.

[0051] (1) A method of adhering an organic conductive film to a laminate having a dielectric layer and an electromagnetic wave shielding layer laminated.

[0052] (2) A method of forming an acid-based organic conductive polymer layer on a laminate having a dielectric layer and an electromagnetic wave shielding layer laminated using a coating method, and adhering a base material layer thereon.

[0053] (3) A method of forming an acid-based organic conductive polymer layer on a laminate having a dielectric layer and an electromagnetic wave shielding layer laminated using a coating method, and extruding a base material layer thereon

[0054] One aspect relates to an electromagnetic wave shielding sheet in which a resistive coating film, a dielectric layer, and an electromagnetic wave shielding layer each having light transmittance are stacked in this order, the resistive coating film including an acid-based organic conductive polymer layer. However, in other modes of the electromagnetic wave shielding sheet, the base material layer of the resistive coating film can also have impermeability (can be completely impermeable or can be incompletely impermeable) to electromagnetic waves in the visible light region.

[0055] In one mode of the electromagnetic wave shielding sheet, the dielectric layer is set to a layer thickness capable of absorbing electromagnetic waves in a high frequency band of 30 GHz to 300 GHz or more of the millimeter wave band, the electromagnetic wave shielding layer is composed of a conductive network, the opening ratio of the conductive network is 35% or more and 85% or less, the total light transmittance is 30% or more, and the attenuation amount of electromagnetic waves in the electromagnetic wave shielding sheet is 20 dB or more.

[0056] In one mode of the electromagnetic wave shielding sheet, the surface resistance value of the electromagnetic wave shielding layer is 0.3 Ω / sq or less.

[0057] In one mode of the electromagnetic wave shielding sheet, the surface resistance value of the resistive coating film is in the range of -15% to +20% relative to the impedance of vacuum.

[0058] <Method for producing an organic conductive film>

[0059] includes: a step of preparing a coating liquid containing an acid-based organic conductive polymer, a base neutralizing agent, and a liquid medium; a step of applying the coating liquid to a base material layer; and a step of removing the liquid medium from the applied coating liquid.

[0060] (Base neutralizing agent)

[0061] In addition to the above-described materials exemplified in the acid-based organic conductive polymer layer, the coating liquid can also contain a base neutralizing agent. As the base neutralizing agent, as long as it is a substance capable of adjusting the pH of the coating liquid and difficult to affect the complex state of the acid-based organic conductive polymer, there is no particular limitation, and for example, hydroxides or carbonates of alkali metals or alkaline earth metals, ammonium compounds such as ammonia, amines, and the like can be listed. From the viewpoint of easy availability, the base neutralizing agent can contain ammonia.

[0062] (Liquid medium)

[0063] As the liquid medium, there is no particular limitation, and for example, water, organic solvents, mixed solvents of water and organic solvents, and the like can be listed.

[0064] The pH of the coating liquid at 25°C is 4.0 to 6.5. By adjusting the pH in this range, excellent light resistance can be imparted to the formed acid-based organic conductive polymer layer. From this viewpoint, the pH of the coating liquid can be 4.5 to 5.5.

[0065] As a method of applying the coating liquid to the substrate layer, there is no particular limitation, and for example, the following coating methods known in the art can be mentioned: gravure coating, reverse roll coating, die coating, air knife coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, extrusion coating, dip coating, kiss coating, spray coating, calendar coating, extrusion coating, and the like.

[0066] As a method of removing the liquid medium, heating removal, reduced pressure removal, and a combination thereof can be mentioned. For example, in the case of removing the liquid medium by heating, the heating temperature can be set to 50 to 200°C, for example, and can be 90 to 150°C. The heating time depends on the heating temperature, and can be set to 30 seconds to 15 minutes, for example, and can be 1 to 5 minutes.

[0067] Examples

[0068] The present application will be described in more detail by the following examples, but the present application is not limited to these examples.

[0069] Preparation of Coating Liquid

[0070] As a poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT-PSS) dispersion liquid, a dispersion liquid Clevios PH1000 (pH = 3) manufactured by Heraeus Corporation was prepared. In addition, as a solution containing an alkali neutralizer, ammonia water (pH = 12) manufactured by Kanto Chemical Co., Inc. was prepared. Then, coating liquids 1 to 3 were prepared in accordance with Table 1. Coating liquid 1 was the dispersion liquid itself, and coating liquids 2 and 3 were solutions prepared by adding ammonia water to the dispersion liquid PH1000 to adjust the pH. The pH of the coating liquid at 25°C was measured by a benchtop pH meter F-37 manufactured by Horiba, Ltd.

[0071] [Table 1]

[0072] Coating liquid pH (25°C) 1 <3 2 5 3 7

[0073] Production of Organic Conductive Film

[0074] Each of the coating liquids was applied to a polyethylene terephthalate substrate (PET, thickness 50 μm) using a bar coater #18, and a coating film was formed. The resulting coating film was heated at 120°C for 1 minute, and thus a PEDOT-PSS layer (thickness about 300 nm) was formed on the PET substrate. Thus, an organic conductive film was produced.

[0075] Evaluation of Organic Conductive Film

[0076] (Cation content in PEDOT-PSS layer)

[0077] The ammonium ions remaining in the PEDOT-PSS layer were quantified using an ion chromatograph DX-320 manufactured by Dionex Corporation. Each organic conductive film (sample size: 1 cm 2 (1 cm x 1 cm) was placed in an extraction solvent (ultra-pure water 100 ml) and left to stand for 24 hours in an environment of 25°C. After diluting the extraction solvent after standing 50 times with ultra-pure water, the ammonium ions were quantified by ion chromatography. From the quantification results, the content of the ammonium ions remaining in the PEDOT-PSS layer was calculated. The results are shown in Table 2.

[0078] (surface resistance change)

[0079] The surface resistance values of the PEDOT-PSS layer before and after the light resistance test were measured at a temperature of 25°C using Loresta-GP (MCP-T610, in-line 4 probe (ASP)) manufactured by Mitsubishi Chemical Analytech Co., Ltd. The number of samples of each organic conductive film (sample size: 25 cm 2 (5 cm x 5 cm) was set to 3, the number of measurements for each sample was set to 5, the surface resistance values were measured for a total of 15 points and the average value was calculated, which was taken as the surface resistance value of each PEDOT-PSS layer. Then, the surface resistance change was calculated according to the following formula. The results are shown in Table 2.

[0080] surface resistance change = surface resistance value after light resistance test / surface resistance value before light resistance test

[0081] (wherein, the light resistance test was performed by using Xenon Weather Meter X75 manufactured by Suga Test Instruments Co., Ltd. under conditions of irradiance 60 W / m 2 , BPT temperature 63°C, tank temperature 40°C, tank humidity 50% rh, test time ~ 500 hours.)

[0082] [Table 2]

[0083]

[0084] In Comparative Example 2, after 500 hours, a surface resistance change of one order of magnitude greater than Example 1 was observed.

[0085] On the other hand, in Example 1, the surface resistance change was suppressed to be very low even after 500 hours, and specifically, the change in surface resistance value was controlled to 300. This value is less than Comparative Example 1.

[0086] Explanation of symbols

[0087] 1…substrate layer, 2…acid-based organic conductive polymer layer, 10…organic conductive film

Claims

1. An organic conductive film comprising a substrate layer and an acid-based organic conductive polymer layer on the substrate layer, wherein the acid-based organic conductive polymer layer contains 4.5–5.0 mg / cm³ of cations derived from an alkali neutralizing agent. 3 , In the determination using the 4-terminal method, the surface resistance change of the acid-based organic conductive polymer layer, expressed by the following formula, is 4.0 × 10⁻⁶. 2 the following, Surface resistance change = Surface resistance value after lightfastness test / Surface resistance value before lightfastness test The lightfastness test refers to the xenon-type accelerated lightfastness test, under the following conditions: radiation irradiance of 60 W / m². 2 BPT temperature 63℃, tank temperature 40℃, tank humidity 50% RH, test time 500 hours. The acid-based organic conductive polymer includes polythiophene-based conductive polymers. The total mass percentage of the polythiophene-based conductive polymer and the polyanionic dopant in the acidic organic conductive polymer layer is 90% or more.

2. The membrane according to claim 1, wherein, The cations from the base neutralizer include ammonium ions.

3. The membrane according to claim 1 or 2, wherein, The substrate layer comprises a resin substrate or a glass substrate.

4. The membrane according to claim 1 or 2, used as a resistive coating in an electromagnetic wave suppression sheet or as a circuit material in an electronic device.

5. The membrane according to claim 3, used as a resistive coating in an electromagnetic wave suppression sheet or as a circuit material in an electronic device.

6. A laminate comprising: a film, a dielectric layer, and an electromagnetic wave shielding layer as described in any one of claims 1 to 5.

7. A method for manufacturing an organic conductive film, comprising the method for manufacturing the organic conductive film according to claim 1, including: The process of preparing a coating solution containing an acid-based organic conductive polymer, an alkali neutralizer, and a liquid medium, with a pH of 4.0 to 6.5 at 25°C; The process of applying the coating liquid onto a substrate layer; and The process of removing the liquid medium from the applied coating liquid.

8. The manufacturing method according to claim 7, wherein, The acid-based organic conductive polymer includes polythiophene-based conductive polymers.

9. The manufacturing method according to claim 7 or 8, wherein, The alkali neutralizer contains ammonia.

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