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

Abstract

To provide a method for producing an organic conductive film excellent in light resistance.SOLUTION: The method for producing an organic conductive film includes the steps of: preparing a coating liquid which contains an acid-based organic conductive polymer, an alkali neutralizer, and a liquid medium and has a pH of 4.0-6.5 at 25°C; applying the coating liquid on a substrate layer; and removing the liquid medium from the applied coating liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing an organic conductive film, an organic conductive film, and a laminate. [Background technology]

[0002] In recent years, liquid crystal display devices, electroluminescent displays, solar cells, touch panels, and the like have become widespread, and in these devices, ITO (indium tin oxide) is laminated onto a film as a transparent electrode. However, there are concerns about the global depletion of indium, the material used in ITO, and safety concerns, so alternative organic materials are being investigated. Examples of such organic materials include π-conjugated conductive polymers, specifically polythiophene-based conductive polymers.

[0003] As a technique for forming a film of a π-conjugated conductive polymer, it is known to use a conductive polymer solution containing a π-conjugated conductive polymer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-105718 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when a solution is prepared in accordance with Patent Document 1, the solution containing an acidic organic conductive polymer may exhibit strong acidity due to its composition. In such cases, from the viewpoints of ensuring safety and inhibiting corrosion of processing equipment, it is conceivable to adjust the pH of the solution to near neutral using a neutralizing agent or the like. However, according to the findings of the inventors, a conductive polymer layer formed using a solution with such a pH adjustment does not have sufficient light resistance.

[0006] The present disclosure has been made in view of the above circumstances, and has an object to provide a method for producing an organic conductive film having excellent light resistance. Another object of the present disclosure is to provide an organic conductive film having excellent light resistance. [Means for solving the problem]

[0007] As a result of extensive research, the inventors have found that the amount of components derived from an alkali neutralizer remaining in a conductive layer formed from a solution containing an acidic organic conductive polymer affects light resistance. Based on this finding, the inventors have completed the present invention.

[0008] A method for producing an organic conductive film according to one aspect of the present disclosure includes the steps of preparing a coating liquid containing an acid-based organic conductive polymer, an alkali neutralizer, and a liquid medium, the coating liquid having a pH of 4.0 to 6.5 at 25°C; applying the coating liquid to a substrate layer; and removing the liquid medium from the applied coating liquid. By using a coating liquid with an adjusted pH, the content of cations derived from the alkali neutralizer in the acid-based organic conductive polymer layer can be appropriately controlled, as described below, resulting in the production of an organic conductive film with excellent light resistance. Thus, the inventors' studies have revealed that in addition to ensuring that the pH is not too high, i.e., that the content of cations derived from the alkali neutralizer is not too high, it is also important that the pH is not too low, i.e., that the content of cations derived from the alkali neutralizer is not too low.

[0009] In one embodiment of the manufacturing method, the acid-based organic conductive polymer may include a polythiophene-based conductive polymer.

[0010] In one embodiment of the manufacturing method, the alkaline neutralizing agent may comprise aqueous ammonia.

[0011] An organic conductive film according to one aspect of the present disclosure includes a substrate layer and an acid-based organic conductive polymer layer on the substrate layer, wherein the content of cations derived from an alkali neutralizer in the acid-based organic conductive polymer layer is 0.5 to 5.0 mg / cm. 3The cation content derived from the alkali neutralizer in the acid organic conductive polymer layer is 0.5 to 5.0 mg / cm 3 By setting the thickness within this range, an organic conductive film having excellent light resistance can be obtained.

[0012] In one embodiment of the organic conductive film, the acid-based organic conductive polymer may include a polythiophene-based conductive polymer.

[0013] In one embodiment of the organic conductive film, the cations derived from the alkaline neutralizer may include ammonium ions.

[0014] In one embodiment of the organic conductive film, the substrate layer may include a resin substrate or a glass substrate.

[0015] In one embodiment, the organic conductive film may be used as a resistive coating in an electromagnetic wave suppression sheet or as a circuit material in an electronic device. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to provide a method for producing an organic conductive film having excellent light resistance. Furthermore, according to the present disclosure, it is possible to provide an organic conductive film having excellent light resistance. Such an organic conductive film can be obtained by the above-mentioned production method. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view of an organic conductive film according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0019] <Organic conductive film> 1 is a schematic cross-sectional view of an organic conductive film according to one embodiment. The organic conductive film 10 includes a substrate layer 1 and an acid-based organic conductive polymer layer 2 on the substrate layer 1.

[0020] (base material layer) The substrate layer functions as a substrate for the organic conductive film. Examples of materials for the substrate layer include resin and glass. That is, the substrate layer may include a resin substrate or a glass substrate, or may be a resin substrate or a glass substrate.

[0021] The resin is not particularly limited, and examples thereof include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, and modified polyester, polyolefin resins such as polyethylene (PE) resin, polypropylene (PP) resin, and cyclic olefin resin, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetal resins such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin, polysulfone (PSF) resin, polyethersulfone (PES) resin, polycarbonate (PC) resin, polyamide resin, polyimide resin, polystyrene resin, acrylic resin, triacetyl cellulose (TAC) resin, etc. From the viewpoints of availability, cost, etc., the resin may be a polyester resin such as PET or PBT, or a polyolefin resin such as PP.

[0022] The glass is not particularly limited, and examples thereof include soda-lime glass, lead glass, borosilicate glass, quartz glass, etc. From the viewpoints of availability, cost, etc., the glass may be soda-lime glass.

[0023] The substrate layer may include one or more layers formed from these materials. When the substrate layer is composed of multiple layers (a laminate), resin substrates may be used in combination, or a resin substrate and a glass substrate may be used in combination. Examples of combinations of resin substrates include a PP layer / PET layer structure and a PP layer / PBT layer structure.

[0024] The thickness of the substrate layer is not particularly limited, but may be, for example, 10 to 200 μm, or may be 25 to 75 μm, from the viewpoints of transparency and strength according to the application. Furthermore, from the viewpoints of coatability of the coating liquid, adhesion to the polymer layer, etc., the surface of the substrate layer may be subjected to corona treatment or easy-adhesion treatment as needed.

[0025] The substrate layer may be transparent or opaque to electromagnetic waves with wavelengths in the visible light region, and is appropriately selected depending on the specifications of the organic conductive film. For example, when the organic conductive film is required to be transparent to electromagnetic waves with wavelengths in the visible light region, a transparent substrate layer may be selected. Furthermore, when a pattern or wood grain design is required on the substrate, the substrate layer may be printed or the surface of the substrate layer may be unevenly formed.

[0026] (Acid-based organic conductive polymer layer) The acid-based organic conductive polymer layer is conductive and includes an acid-based organic conductive polymer. In this specification, the term "acid-based organic conductive polymer" refers to a conductive complex containing a π-conjugated conductive polymer and a polyanion dopant for the π-conjugated conductive polymer. The π-conjugated conductive polymer is not particularly limited, and examples thereof include polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylene vinylene, polynaphthalene, and derivatives thereof. Among these, from the viewpoints of transparency, conductivity, stability, and the like, the π-conjugated conductive polymer may particularly be a polythiophene-based conductive polymer.

[0027] Examples of polythiophene-based conductive polymers include 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), and 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-dodecathiophene), siloxythiophene), 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- Examples of suitable polythiophene-based conductive polymers include 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), and poly(3-methyl-4-carboxybutylthiophene). The polythiophene-based conductive polymer may be poly(3,4-ethylenedioxythiophene) from the viewpoints of conductivity, chemical stability, productivity, and the like.

[0028] The polythiophene-based conductive polymers can be used singly or in combination of two or more.

[0029] The acid-based organic conductive polymer layer contains a polyanion dopant for the π-conjugated conductive polymer. This can improve the conductivity of the acid-based organic conductive polymer layer. Examples of polyanion dopants include polymeric acids having sulfo groups, such as alkanesulfonic acid, polystyrenesulfonic acid, polyvinylsulfuric acid, polyvinylsulfonic acid, polyallylsulfonic acid, polyacrylicsulfonic acid, polymethacrylicsulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, polysulfoethyl methacrylate, poly(4-sulfobutyl methacrylate), and polymethacryloxybenzenesulfonic acid, and organic acids having sulfo groups, such as p-toluenesulfonic acid and dodecylbenzenesulfonic acid. The polyanion dopant may be polystyrenesulfonic acid from the viewpoints of chemical stability and conductivity.

[0030] The polyanion dopants can be used singly or in combination of two or more.

[0031] At least a portion of the polythiophene-based conductive polymer and at least a portion of the polyanion dopant form a conductive complex within the layer. From the viewpoints of transparency, conductivity, etc., the conductive complex may be poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT-PSS), which is a complex of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrenesulfonic acid (PSS).

[0032] The acid-based organic conductive polymer layer may contain components other than the polythiophene-based conductive polymer and the polyanion dopant (e.g., a binder) as long as the intended effect is 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 may be 50% by mass or more, 80% by mass or more, or 90% by mass or more.

[0033] The thickness of the acid-based organic conductive polymer layer is not particularly limited, but can be, for example, 10 nm to 1 μm, and may be 200 to 600 nm.

[0034] As described below, the acid-based organic conductive polymer layer can be formed by applying a coating liquid containing an acid-based organic conductive polymer and an alkali neutralizer and having a pH of 4.0 to 6.5 at 25° C. onto the substrate layer. The content of cations derived from the alkali neutralizer in the acid-based organic conductive polymer layer is set to 0.5 to 5.0 mg / cm from the viewpoint of maintaining excellent light resistance. 3 However, 3.0 to 5.0 mg / cm 3 and may be 4.5 to 5.0 mg / cm 3 It is presumed that the reason why the acid-based organic conductive polymer layer contains a certain amount or more of cations is that the cations are trapped by hydrogen bonding or the like with the acid-based organic conductive polymer, and remain in the layer even after the liquid medium is removed.

[0035] The cation content 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 a 25°C environment. After standing, the extraction solvent is diluted 50 times with ultrapure water, and the cations are quantified by ion chromatography. Based on the quantification results, the content of cations remaining in the acid-based organic conductive polymer layer can be calculated.

[0036] The cations derived from the alkali neutralizer may contain ammonium ions. In this case, the amount of ammonium ions present in the acidic organic conductive polymer layer is 0.5 to 5.0 mg / cm as measured by ion chromatography. 3 and the concentration can be 3.0 to 5.0 mg / cm 3 and may be 4.5 to 5.0 mg / cm 3 It may be.

[0037] The acid-based organic conductive polymer layer has excellent light resistance, which means that the surface resistance is unlikely to increase over time. The change in surface resistance of the acid-based organic conductive polymer layer, as shown in the following formula, is 4.0 × 10 when measured by the four-terminal method. 2 may be less than or equal to 3.0 x 10 2 It may be the following: Change in surface resistance = Surface resistance after light resistance test / Surface resistance before light resistance test However, the light resistance test is an accelerated light resistance test using a xenon type (conditions: irradiance 60W / m 2 , BPT temperature 63°C, temperature inside the chamber 40°C, humidity inside the chamber 50%rh, test time 500 hours).

[0038] Organic conductive films can be used as, but are not limited to, resistive coatings in electromagnetic wave suppression sheets or circuit materials in electronic devices. Organic conductive films are used as resistive coating layers in electromagnetic wave suppression sheets, such as those described in Japanese Patent No. 6523563. Organic conductive films are also used as hole transport layers in electronic devices, such as those described in Japanese Patent Laid-Open No. 2005-71929.

[0039] <Electromagnetic wave suppression sheet> The electromagnetic wave suppression sheet can be said to be a laminate comprising an organic conductive film, a dielectric layer, and an electromagnetic wave shielding layer. There are no particular restrictions on the method for producing the electromagnetic wave suppression sheet, but examples include the following method. (1) A method of adhering an organic conductive film to a laminate in which a dielectric layer and an electromagnetic wave shielding layer are laminated. (2) A method in which an acid-based organic conductive polymer layer is formed by coating on a laminate in which a dielectric layer and an electromagnetic wave shielding layer are laminated, and a substrate layer is then adhered onto the layer. (3) A method in which an acid-based organic conductive polymer layer is formed by coating on a laminate in which a dielectric layer and an electromagnetic wave shielding layer are laminated, and a substrate layer is extruded onto the layer.

[0040] An electromagnetic wave suppression sheet according to one aspect comprises a resistive coating, a dielectric layer, and an electromagnetic wave shielding layer laminated in that order, all of which are light-transmitting, and the resistive coating includes an acid-based organic conductive polymer layer. However, in another aspect of the electromagnetic wave suppression sheet, the substrate layer of the resistive coating may be opaque (either completely opaque or partially opaque) to electromagnetic waves in the visible light range.

[0041] In one embodiment of the electromagnetic wave suppression sheet, the dielectric layer has a thickness that allows it to absorb electromagnetic waves in the high-frequency band of 30 GHz to 300 GHz, or higher than the millimeter wave band, the electromagnetic wave shielding layer is made of a conductive mesh, the conductive mesh has an aperture ratio of 35% to 85% and a total light transmittance of 30% or higher, and the electromagnetic wave attenuation in the electromagnetic wave suppression sheet is 20 dB or higher.

[0042] In one embodiment of the electromagnetic wave suppression sheet, the surface resistance of the electromagnetic wave shielding layer is 0.3 Ω / sq or less.

[0043] In one embodiment of the electromagnetic wave suppression sheet, the surface resistance of the resistive coating is in the range of −15% to +20% of the vacuum impedance.

[0044] <Method of manufacturing organic conductive film> The method includes the steps of preparing a coating liquid containing an acid-based organic conductive polymer, an alkali neutralizing agent, and a liquid medium, applying the coating liquid onto a substrate layer, and removing the liquid medium from the applied coating liquid.

[0045] (Alkaline neutralizer) The coating liquid contains an alkali neutralizer in addition to the materials exemplified for the acid organic conductive polymer layer. The alkali neutralizer is not particularly limited as long as it can adjust the pH of the coating liquid and does not easily affect the complex state of the acid organic conductive polymer, and examples thereof include hydroxides and carbonates of alkali metals and alkaline earth metals, ammonium compounds such as ammonia, and amines. From the viewpoint of easy availability, the alkali neutralizer may contain ammonia.

[0046] (liquid medium) The liquid solvent is not particularly limited, and examples thereof include water, organic solvents, and mixed solvents of water and organic solvents.

[0047] The pH of the coating liquid at 25° C. is 4.0 to 6.5. By adjusting the pH within this range, the acid-based organic conductive polymer layer formed can be imparted with excellent light resistance. From this perspective, the pH of the coating liquid may be 4.5 to 5.5.

[0048] The method for applying the coating liquid onto the substrate layer is not particularly limited, and examples thereof include conventionally known coating methods such as gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, impregnation coating, kiss coating, spray coating, calendar coating, and extrusion coating.

[0049] Methods for removing the liquid medium include removal by heating, removal by reducing pressure, and a combination thereof. For example, when removing the liquid medium by heating, the heating temperature can be, for example, 50 to 200°C, and may be 90 to 150°C. The heating time depends on the heating temperature, but can be, for example, 30 seconds to 15 minutes, and may be 1 to 5 minutes. [Example]

[0050] The present invention will be described in more detail by the following examples, but the present invention is not limited to these examples.

[0051] <Preparation of coating liquid> Clevios PH1000 (pH = 3), a dispersion liquid manufactured by Heraeus Inc., was prepared as a poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT-PSS) dispersion liquid. Furthermore, ammonia water (pH = 12), manufactured by Kanto Chemical Co., Inc., was prepared as a solution containing an alkali neutralizer. Coating Liquids 1 to 3 were then prepared according to Table 1. Coating Liquid 1 was the above dispersion liquid itself, while Coating Liquids 2 and 3 were prepared by adjusting the pH by adding ammonia water to Dispersion Liquid PH1000. The pH of the coating liquids at 25°C was measured using a benchtop pH meter F-37 manufactured by Horiba, Ltd.

[0052] [Table 1]

[0053] <Preparation of organic conductive film> Each coating solution was applied to a polyethylene terephthalate (PET) substrate (50 μm thick) using a bar coater #18 to form a coating film. The resulting coating film was heated at 120°C for 1 minute to form a PEDOT-PSS layer (approximately 300 nm thick) on the PET substrate. This produced an organic conductive film.

[0054] <Evaluation of organic conductive films> (cation content in PEDOT-PSS layer) The amount of ammonium ions remaining in the PEDOT-PSS layer was quantified using an ion chromatograph DX-320 manufactured by Dionex Corporation. 2 The sample (1cm x 1cm) was placed in an extraction solvent (100ml of ultrapure water) and left to stand at 25°C for 24 hours. After leaving the extraction solvent, it was diluted 50 times with ultrapure water and the ammonium ions were quantified using ion chromatography. Based on the quantitative results, the amount of ammonium ions remaining in the PEDOT-PSS layer was calculated. The results are shown in Table 2.

[0055] (Surface resistance change) The surface resistance of the PEDOT-PSS layer was measured at 25°C using a Loresta-GP (MCP-T610, serial 4-point probe (ASP)) manufactured by Mitsubishi Chemical Analytech Co., Ltd. The surface resistance of each organic conductive film (sample size: 25 cm) was measured before and after the light resistance test. 2 Three samples (5cm x 5cm) were used, and each sample was measured five times. The surface resistance was measured at a total of 15 points, and the average value was taken as the surface resistance value of each PEDOT-PSS layer. The change in surface resistance was then calculated using the following formula. The results are shown in Table 2. Change in surface resistance = Surface resistance after light resistance test / Surface resistance before light resistance test (However, the light resistance test was performed using a Xenon Weather Meter X75 manufactured by Suga Test Instruments Co., Ltd., at an irradiance of 60 W / m 2 The test was carried out under the following conditions: BPT temperature 63°C, chamber temperature 40°C, chamber humidity 50% rh, test time 500 hours.

[0056] [Table 2]

[0057] In Comparative Example 2, a change in surface resistance that was one order of magnitude larger than that of Example 1 was observed after 500 hours had elapsed.

[0058] On the other hand, in Example 1, the change in surface resistance was kept low even after 500 hours had passed, and specifically, the change in surface resistance value was kept within 300. This value was smaller than that of Comparative Example 1. [Explanation of symbols]

[0059] 1...base material layer, 2...acid-based organic conductive polymer layer, 10...organic conductive film.

Claims

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

2. The method according to claim 1 , wherein the acid-based organic conductive polymer comprises a polythiophene-based conductive polymer.

3. The method according to claim 1 or 2, wherein the alkaline neutralizing agent comprises ammonia.

4. A substrate layer and an acid-based organic conductive polymer layer on the substrate layer, wherein the content of cations derived from an alkali neutralizer in the acid-based organic conductive polymer layer is 0.5 to 5.0 mg / cm ３ That is, organic conductive film.

5. The film according to claim 4 , wherein the acid-based organic conductive polymer comprises a polythiophene-based conductive polymer.

6. 6. The film of claim 4 or 5, wherein the cations derived from the alkaline neutralizing agent comprise ammonium ions.

7. The film according to any one of claims 4 to 6, wherein the substrate layer comprises a resin substrate or a glass substrate.

8. The film according to any one of claims 4 to 7, which is used as a resistive coating in an electromagnetic wave suppression sheet or as a circuit material in an electronic device.

9. A laminate comprising the film according to any one of claims 4 to 8, a dielectric layer, and an electromagnetic wave shielding layer.

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