JP6591785B2 - Manufacturing method of conductive sheet and conductive sheet manufactured by the manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a conductive sheet and a conductive sheet produced by the production method.

  In recent years, thiophene-based polymers have excellent stability and conductivity, and are expected to be used as organic conductive materials. As one of the applications, a coating composition in which a conductive polymer in which a dopant is added to the above polymer is dispersed in a solvent is used to form a transparent electrode used in various devices such as a liquid crystal display and a transparent touch panel. Yes.

  However, poly (3,4-ethylenedioxythiophene) is used as the thiophene polymer, and a mixture (also referred to as PEDOT / PSS) using polystyrene sulfonic acid as the dopant is used as a coating composition. When a conductive film is formed on a substrate using the composition and the conductive film is left in the atmosphere, there is a problem that the surface electrical resistance value of the conductive film changes with time. This is because PSS, which is a dopant in the conductive film, is ionized due to the influence of water vapor and pollutants such as salt in the atmosphere, and a part of PSS becomes sulfonate ions or sulfonates. This is probably because PSS as a dopant is desorbed from a certain PEDOT and the function of the PSS as a dopant is lowered.

  For such a problem, for example, Patent Document 1 proposes forming a protective layer by thermocompression bonding an insulating sheet to a conductive layer made of a polythiophene-based conductive polymer.

  On the other hand, Non-Patent Document 1 discloses that the surface electrical resistance of the conductive film is reduced by performing acid treatment on the conductive film made of PEDOT / PSS.

JP 2007-52975 A

Applied Materials & Interfaces, Vol.2, No.2, 474-483, 2010 “Significant Conductivity Enhancement of Conductive Poly (3,4-ethylenedioxythiophene): Poly (styrenesulfonate) Films through a Treatment with Organic Carboxylic Acids and Inorganic Acids”

  By using the protective layer described in Patent Document 1, the conductive layer can be shielded from the atmosphere, but the formation of a transparent electrode used in various devices such as a touch panel requires a conductive layer patterning step, In the patterning process, it is inevitable that the conductive layer comes into contact with the atmosphere.

  In addition, the acid treatment described in Non-Patent Document 1 reduces the surface electrical resistance of the conductive film by desorbing PSS from PEDOT / PSS constituting the conductive film, but from PEDOT / PSS, When the PSS which is a dopant is desorbed, the function of the PSS as a dopant is lowered, so that the surface electrical resistance value of the conductive film is changed. The surface electrical resistance value of the transparent electrode used in various devices such as a touch panel is set strictly for each device, and it is necessary to suppress the change in the surface electrical resistance value of the conductive film used for the transparent electrode as much as possible.

  The present invention has been made in order to solve the above-described problems, and has been manufactured by a method for manufacturing a conductive sheet capable of reducing the change over time of the surface electrical resistance value of a conductive film containing a conductive polymer, and the manufacturing method thereof. A conductive sheet is provided.

  The method for producing a conductive sheet according to the present invention is a method for producing a conductive sheet comprising a base material and a conductive layer disposed on at least one main surface of the base material, the conductive polymer, and a binder. A conductive layer is formed on the substrate by applying a coating preparation step for forming a conductive layer forming coating containing a resin and a solvent, and applying the conductive layer forming coating on the substrate and drying the coating. A conductive layer forming step, and an acid contact step of bringing the conductive layer into contact with an acidic aqueous solution.

  Moreover, the conductive sheet of the present invention is a conductive sheet including a base material and a conductive layer disposed on at least one main surface of the base material, and the conductive sheet manufacturing method of the present invention described above is used. It is manufactured.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive sheet with a small temporal change of the surface electrical resistance value of the conductive layer containing a conductive polymer can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of the conductive sheet of the present invention.

(Method for producing conductive sheet of the present invention)
The method for producing a conductive sheet according to the present invention is a method for producing a conductive sheet comprising a base material and a conductive layer disposed on at least one main surface of the base material, the conductive polymer, and a binder. A conductive layer is formed on the base material by applying a coating process for forming the conductive layer forming paint containing a resin and a solvent, and drying the conductive layer forming paint on the base material. A conductive layer forming step, and an acid contact step for bringing the conductive layer into contact with an acidic aqueous solution.

<Paint preparation process>
The coating material preparation step of the present invention is a step of preparing a conductive layer forming coating material containing a conductive polymer, a binder resin, and a solvent.

[Conductive polymer]
A polythiophene compound can be used as the conductive polymer used in the conductive layer forming coating.

  Examples of the polythiophene compound include poly (thiophene), 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-decyloxy) Thiophene), 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), Li (3,4-didodecyloxythiophene), poly (3,4-ethylenedioxythiophene), poly (3,4-propylenedioxythiophene), poly (3,4-butenedioxythiophene), 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) and the like. The said polythiophene type compound may be used individually by 1 type, and may use 2 or more types together.

  In the present invention, a dopant is used in combination to increase the electrical conductivity of the conductive polymer. Protonic acids such as nitric acid and sulfuric acid can be used as the dopant.

  In the present invention, it is preferable to use a polymer containing a polythiophene compound and a dopant as the conductive polymer, poly (3,4-ethylenedioxythiophene) as the polythiophene compound, and polystyrene sulfone as the dopant. Most preferably, a mixture using acid (PEDOT / PSS) is used.

  Content of the said conductive polymer in the said coating material for conductive layer formation is 0.7 mass% or more and 70.0 mass% or less with respect to the mass of the total solid component contained in the said coating material for conductive layer formation. preferable. When the content of the conductive polymer is less than 0.7% by mass with respect to the mass of all solid components contained in the conductive layer forming coating material, the conductivity of the conductive layer is decreased, and 70.0% by mass is obtained. If it exceeds, the physical properties and wet heat resistance of the conductive layer tend to be lowered.

[Binder resin]
Since the conductive layer forming paint contains a binder resin, when the conductive sheet is formed, the adhesion between the conductive layer and the base material is improved, and the conductive layer is peeled off from the base material. Can be suppressed. In addition, by using the binder resin, when the conductive layer is formed, the dopant is not detached from the conductive polymer, and the change in the surface electrical resistance value of the conductive layer can be reduced. As described above, by using the binder resin, a physically and chemically durable conductive layer can be formed. Furthermore, when the conductive layer contains a binder resin, the water resistance of the conductive layer is improved.

  The binder resin is preferably a fluorine resin or a silicone resin. This is because these resins are excellent in water resistance and have high resistance to an acidic aqueous solution described later.

  As the fluororesin, for example, polyvinylidene fluoride (PVDF), vinylidene fluoride-acrylic copolymer, vinylidene fluoride-hexafluoropropylene copolymer, or the like is preferably used. From the viewpoint of further improving the adhesiveness of PVDF, PVDF is more preferable. By using the fluororesin, a conductive layer having high water resistance and transparency can be formed.

  As the silicone resin, an alkoxysilane monomer or an alkoxysilane oligomer can be used. By using the silicone resin, a conductive layer having a high hardness can be formed. The said silicone resin may be used independently and may be used in combination of 2 or more type.

  Examples of the alkoxysilane monomer include tetraethoxysilane, tetramethoxysilane, tetrapropylsilane, tetrabutoxysilane, vinylmethoxysilane, p-styrylmethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, and methyl. Examples include triethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane, and the like.

  As the alkoxysilane oligomer, those obtained by condensing the alkoxysilane monomer can be used. For example, alkoxysilane oligomers “KR-500”, “KC-89S”, “X-” manufactured by Shin-Etsu Chemical Co., Ltd. 40-9225 ”,“ X-40-9226 ”,“ X-40-9250 ”,“ X-40-2308 ”,“ X-40-9238 ”(trade name), silicate oligomer“ ethyl silicate ”manufactured by Colcoat 40 ”,“ ethyl silicate 48 ”,“ methyl silicate 51 ”,“ methyl silicate 53A ”,“ EMS-485 ”,“ SS-101 ”(trade name), and the like.

  The content of the binder resin is preferably 30.0% by mass or more and 99.3% by mass or less, more preferably 65.0% by mass or more and 95.% by mass with respect to the total mass of the conductive polymer and the binder resin. 0% by mass or less. If the content of the binder resin is too small, it tends to be difficult to obtain sufficient adhesion between the conductive layer and the substrate. If the content of the binder resin is too large, the conductive polymer in the conductive layer is electrically conductive. There is a tendency that the path is not sufficiently formed, and the surface electrical resistance value of the conductive layer tends to decrease.

[solvent]
The solvent used for the conductive layer-forming coating material preferably contains a protic polar solvent and an aprotic polar solvent. By using a protic polar solvent and an aprotic polar solvent in combination, a homogeneous conductive sheet can be obtained in a relatively short time and at a low drying temperature.

  Examples of the protic polar solvent include water, ethyl alcohol, methyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol, acetic acid, and the like. Examples of the polar solvent include dimethyl sulfoxide, N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylformamide, acetonitrile, acetone, tetrahydrofuran and the like.

  The content of the aprotic polar solvent is preferably 1.0% by mass or more and 50.0% by mass or less with respect to the total mass of the solvent. If the content of the aprotic polar solvent is less than 1.0% by mass with respect to the total mass of the solvent, the optical properties of the conductive layer tend to deteriorate, and if it exceeds 50.0% by mass, There is a tendency for the heat and humidity resistance to decrease.

  Although total content of the said solvent is not specifically limited, What is necessary is just to be 50.0 mass% or more and 99.5 mass% or less with respect to the total mass of the said coating material for conductive layer formation. The solvent may contain a nonpolar solvent.

<Conductive layer formation process>
The conductive layer forming step of the present invention is a step of forming a conductive layer on the substrate by applying the conductive layer forming coating material onto the substrate and drying it.

  Examples of the method for applying the conductive layer-forming coating material on a substrate include a bar coating method, a reverse method, a gravure coating method, a micro gravure coating method, a die coating method, a dipping method, a spin coating method, a slit coating method, A coating method such as a spray coating method can be used.

  The drying after the application may be performed under the condition that the solvent component of the coating material for forming a conductive layer evaporates, and is preferably performed at 100 to 150 ° C. for 5 to 60 minutes. If the solvent remains in the conductive layer, the strength tends to be inferior. As a drying method, for example, a hot air drying method, a heat drying method, a vacuum drying method, natural drying, or the like can be used. If necessary, the conductive layer may be formed by irradiating the coating film with UV light or EB light to cure the coating film.

  Although it does not specifically limit as said base material, The transparent base material which has transparency is preferable. As the material for the transparent substrate, for example, various materials such as resin, rubber, glass and ceramics can be used.

<Acid contact process>
The acid contact step of the present invention is a step of bringing the conductive layer into contact with an acidic aqueous solution.

  By bringing the acidic aqueous solution into contact with the conductive layer containing the conductive polymer and the dopant, the change over time in the surface electrical resistance value of the conductive layer of the conductive sheet can be reduced. The mechanism is not clear, but it is thought as follows.

  That is, by bringing an acidic aqueous solution into contact with a conductive layer containing a conductive polymer and a dopant, ionization of the dopant can be suppressed and desorption of the dopant can be prevented. For this reason, the conductive sheet is exposed to the atmosphere. However, it is considered that the function as a dopant in the conductive layer does not deteriorate, and the change over time of the surface electrical resistance value of the conductive layer of the conductive sheet can be reduced.

For example, when a conductive layer is produced using PEDOT as the conductive polymer and PSS as the dopant, the ionization of PSS is considered to be in the following equilibrium state when the conductive layer is placed in an atmosphere containing moisture. It is done.
^{_{-SO 3 H ⇔ -SO 3 - +}} H +

  In the above equilibrium state, when an acidic aqueous solution having an acidity equal to or higher than that of sulfonic acid is brought into contact with the conductive layer, the above equilibrium equation shifts to the left, and it is considered that ionization of PSS can be suppressed. Moreover, even if it makes it dry after making acidic aqueous solution contact the said conductive layer, since the acid component remains on the surface of a conductive layer, it is thought that the ionization suppression effect of said PSS is maintained.

  Moreover, since the said conductive layer contains binder resin, even if it makes it contact with the said acidic aqueous solution, the said conductive layer does not peel from a base material. On the other hand, in Non-Patent Document 1 described above, since the conductive film made of PEDOT / PSS contains no binder resin, there is a concern about peeling of the conductive film made of PEDOT / PSS due to acid treatment.

  The acidity of the acidic aqueous solution needs to be equal to or higher than the acidity of the dopant used. The acidity of sulfonic acid is particularly large among organic acids, and the pH of the aqueous solution of PEDOT / PSS is about 2 to 3. Accordingly, the pH of the acidic aqueous solution is preferably less than 3, and more preferably less than 2.

  As the acid contained in the acidic aqueous solution, for example, at least one selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid and hydroiodic acid can be used. Among these, sulfuric acid, nitric acid, and hydrochloric acid that are easy to handle and hardly cause side reactions are preferable, and sulfuric acid and hydrochloric acid are particularly preferable. The acid aqueous solution may be used by diluting the acid with pure water and adjusting to a predetermined pH.

  The temperature of the acidic aqueous solution is preferably 10 ° C. or higher and 45 ° C. or lower, and more preferably 20 ° C. or higher and 40 ° C. or lower. If the temperature of the acidic aqueous solution is high, the acid contact process time can be shortened, but if the temperature is too high, a part of the conductive layer may be dissolved. Moreover, when the temperature of the said acidic aqueous solution is too low, it is necessary to lengthen an acid contact process time, and production efficiency will fall.

  If the acidic aqueous solution is brought into contact with the conductive layer for too long, the acid treatment effect is saturated, and at the same time a part of the conductive layer may be dissolved. Depending on the temperature of the acidic aqueous solution, the acid treatment effect and production In view of the property, it is preferably 5 seconds or longer and 30 minutes or shorter, and more preferably 10 seconds or longer and 10 minutes or shorter. Moreover, the one where the said acid contact process time is short becomes possible from the surface of productivity, since the continuous production by the roll of a conductive sheet, a roll-to-roll, or a sheet | seat is attained.

  The method for bringing the conductive sheet into contact with the acidic aqueous solution under the above conditions is not particularly limited, and may be performed by a method such as dipping or spraying. For example, when the conductive sheet using the resin base material is continuously produced by roll-to-roll, it is sufficient to bring the acidic aqueous solution into contact with the conductive sheet by immersing it in a water tank containing the acidic aqueous solution. In the case of a conductive sheet using a hard substrate such as glass, the acidic aqueous solution may be brought into contact with the conductive sheet by spraying the acidic aqueous solution while being moved by a conveyor.

  After the acid contact step, the conductive sheet may be washed with pure water. This is because if the next process is performed in a state where a large amount of non-volatile acidic aqueous solution remains on the surface of the conductive sheet, the remaining acidic aqueous solution may adversely affect the next process. The method for washing the conductive sheet with pure water is not particularly limited, and the conductive sheet may be immersed in a water tank containing pure water, or pure water may be sprayed onto the conductive sheet. Although the said washing | cleaning time may be 1 second-5 minutes depending on the use of an electroconductive sheet, when the washing | cleaning time exceeds 5 minutes, the effect made to contact acidic aqueous solution may be impaired.

<Patterning process>
In the method for producing a conductive sheet of the present invention, after forming a resist film at a position where a conductive pattern is formed on the conductive layer, an inert agent that deactivates the conductivity is used, using the resist film as a mask, The method may further comprise a step of patterning the conductive layer by deactivating the conductivity of the exposed portion of the conductive layer.

  The resist film formed at the position where the conductive pattern on the conductive layer is formed can be formed, for example, by screen printing a resist agent on the conductive layer. The said resist agent is not specifically limited, It can select suitably.

  As an inert agent used in order to deactivate the electroconductivity of the exposed part of the said conductive layer, what is necessary is just to be able to deactivate the said conductive polymer, For example, an oxidizing compound and a basic compound are mentioned.

  Examples of the oxidizing compound include hydrogen peroxide compounds, perchloric acid compounds, hypochlorous acid compounds, peracetic acid compounds, metachlorobenzoic acid compounds, sulfite compounds, and the like.

  Examples of the basic compound include ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, pyridine, 4-methylpyridine, and tetramethylammonium hydroxide.

  In the patterning step, since the conductive layer contains a binder resin, the inert agent hardly penetrates into the conductive layer. For this reason, since the inactive agent gradually penetrates into the conductive layer, a conductive pattern can be formed with high accuracy.

(Conductive sheet of the present invention)
The conductive sheet of the present invention comprises a base material and a conductive layer disposed on at least one main surface of the base material, and is manufactured by the method for manufacturing a conductive sheet of the present invention. .

  Since the electroconductive sheet of this invention is manufactured by the manufacturing method of the electroconductive sheet of the said invention, the said conductive layer contains binder resin. Thereby, it is possible to form a conductive layer having high hardness and high adhesion to the substrate as compared to a conductive layer made of only a conductive polymer. In addition, since the conductive layer contains a binder resin, a conductive layer having a small thickness variation can be formed on the base material, so that the electrical resistance value of the entire conductive layer can be made uniform. Furthermore, the conductive layer may be patterned, whereby a conductive layer suitable for touch panel use can be formed.

  The surface electrical resistance value of the conductive layer is preferably 50Ω / sq or more and 10,000Ω / sq or less. Furthermore, when the conductive layer is used as an electrode for a touch panel, the surface electrical resistance value of the conductive layer is preferably 50Ω / sq to 1000Ω / sq, more preferably 50Ω / sq to 500Ω / sq. The smaller the surface electrical resistance value, the better the electrical characteristics. The surface electrical resistance value of the conductive layer can be measured by a contact type four-probe method, a non-contact type eddy current method, or the like.

When the surface electrical resistance value of the conductive layer before being brought into contact with the acidic aqueous solution is Ra and the surface electrical resistance value of the conductive layer after being brought into contact with the acidic aqueous solution is Rb, the following formula (1) is satisfied. Is preferred. Thereby, the influence by the acid treatment of the said conductive layer can be made small.
(| Rb-Ra | / Ra) × 100 <10 (1)

The surface electrical resistance value of the conductive layer before contact with the acidic aqueous solution was Ra, and the conductive layer after contact with the acidic aqueous solution was exposed to the atmosphere at a temperature of 25 ° C. and a relative humidity of 50% for 10 days. When the surface electrical resistance value of the conductive layer later is Rc, the following formula (2) is preferably satisfied. Thereby, the heat-and-moisture resistance of the said conductive layer can be improved.
(| Rc−Ra | / Ra) × 100 <10 (2)

Furthermore, the surface electrical resistance value of the conductive layer before being brought into contact with the acidic aqueous solution is defined as Ra, and the surface of the conductive layer after being brought into contact with the acidic aqueous solution is loaded with white water containing pure water and loaded with 100 g. / Cm ² , speed 4500 mm / min, sliding width 25 mm, and when the surface electrical resistance value of the conductive layer after 20 reciprocations is Rd, the following formula (3) is preferably satisfied. Thereby, the durability of the conductive layer can be improved.
(| Rd−Ra | / Ra) × 100 <10 (3)

  Although the thickness of the said conductive layer is suitably set according to a use, it is about 0.01-10 micrometers normally. If the conductive layer is too thin or too thick, it is difficult to form a uniform conductive layer. Depending on the proportion of the conductive polymer, when the thickness of the conductive layer is less than 0.01 μm, the surface electrical resistance value tends to increase or the variation in the surface electrical resistance value tends to increase. When the thickness of the conductive layer is greater than 10 μm, the thickness of the conductive layer becomes too large and the total light transmittance tends to decrease.

  Next, the electroconductive sheet of this invention is demonstrated based on drawing. FIG. 1 is a schematic cross-sectional view showing an example of the conductive sheet of the present invention. In FIG. 1, the conductive sheet 10 includes a base material 11 and a conductive layer 12 formed on the base material 11. As described above, the conductive layer 12 includes a conductive polymer and a binder resin, and the conductive layer 12 is formed in contact with an acidic aqueous solution.

  Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples. Unless otherwise indicated, in the following, “part” means “part by mass”.

Example 1
<Preparation of paint for forming conductive layer>
The following components were added and mixed to prepare a conductive layer forming coating material a.
(1) Conductive polymer dispersion (manufactured by Heraeus, trade name “PH-1000”, conductive polymer: PEDOT-PSS, solid content concentration: 1.0 mass%, solvent: water): 46 parts (2 ) Binder resin dispersion (PVDF dispersion, average dispersion particle size of PVDF particles: 0.2 μm, solid content concentration: 30% by mass, solvent: water): 4.5 parts (3) Aprotic polar solvent (dimethyl sulfoxide ): 12 parts (4) Protic polar solvent (normal propyl alcohol): 36 parts (5) Protic polar solvent (water): 1.5 parts

<Formation of conductive sheet>
Next, a PET film having a thickness of 100 μm (manufactured by Toyobo Co., Ltd., trade name “A4100”, haze: 0.9%, total light transmittance: 92.0%) was used as a base material, and one main surface of the base material The conductive layer-forming coating material a was applied using a bar coater and then dried at 110 ° C. for 5 minutes. Thereby, the electroconductive sheet of Example 1 in which the electroconductive layer was formed in one main surface was produced. The thickness of the conductive layer was 0.3 μm.

<Measurement of surface electrical resistance value Ra of conductive layer immediately after production>
First, the surface electrical resistance value Ra of the conductive layer immediately after the production of the conductive sheet was measured using a resistivity measuring device “Loresta-GP” (MCP-T610 type) manufactured by Mitsubishi Chemical Analytech Co., Ltd. and an LSP probe. . As a result, Ra was 180Ω / sq.

<Acid contact of conductive sheet>
The produced conductive sheet was cut into a 5 cm square, and the cut conductive sheet was immersed in 100 mL of sulfuric acid aqueous solution (pH: 1.5) having a temperature of 25 ° C. and a concentration of 0.1 N for 10 seconds. Thereafter, the conductive sheet was immersed in pure water for 5 seconds, washed and dried.

<Measurement of surface electrical resistance value Rb of conductive layer after acid contact>
Next, the surface electrical resistance value Rb of the conductive layer of the conductive sheet after the acid contact is measured using a resistivity measuring device “Loresta-GP” (MCP-T610 type) manufactured by Mitsubishi Chemical Analytech Co., Ltd. and an LSP probe. did.

<Measurement of surface electrical resistance value Rc after wet heat resistance test of conductive layer>
The surface electricity of the conductive layer of the conductive sheet after leaving the conductive sheet after contact with the acidic aqueous solution for 10 days in a state where it is shielded from light in a constant temperature and humidity chamber having a temperature of 25 ° C. and a relative humidity of 50%. The resistance value Rc was measured using a resistivity measuring device “Loresta-GP” (MCP-T610 type) manufactured by Mitsubishi Chemical Analytech Co., Ltd. and an LSP probe.

<Measurement of surface electrical resistance value Rd after sliding test of conductive layer>
The surface of the conductive layer of the conductive sheet after being contacted with the acidic aqueous solution was loaded with white water (# 400) containing pure water using a load of 100 g / cm ² , a speed of 4500 mm / min, and a sliding width of 25 mm. Then, Rd was measured for the surface electrical resistance value of the conductive layer after 20 reciprocations using a resistivity measuring device “Loresta-GP” (MCP-T610 type) manufactured by Mitsubishi Chemical Analytech Co., Ltd. and an LSP probe. did.

<Calculation of change rate of surface electric resistance value of conductive layer>
Using the surface electrical resistance values Ra, Rb, Rc, and Rd measured above, from the following formulas (4) to (6), the change rate CR1 of the surface electrical resistance value before and after the acid contact, the surface electrical power before and after the wet heat resistance test The change rate CR2 of the resistance value and the change rate CR3 of the surface electrical resistance value before and after the sliding test were calculated.

CR1 (%) = (| Rb−Ra | / Ra) × 100 (4)
CR2 (%) = (| Rc−Ra | / Ra) × 100 (5)
CR3 (%) = (| Rd−Ra | / Ra) × 100 (6)

  As a result of the measurement, when the rate of change of the surface electrical resistance value is less than 5%, the change in the surface electrical resistance value of the conductive layer of the conductive sheet is judged to be extremely small and excellent (A). When the rate of change of the surface electrical resistance is 5% or more and less than 10%, the change in the surface electrical resistance value of the conductive layer of the conductive sheet is small and judged as good (B), and the rate of change in the surface electrical resistance value exceeds 10% In this case, the change in the surface electrical resistance value of the conductive layer of the conductive sheet was large, and it was judged as defective (C).

(Example 2)
A conductive sheet was produced in the same manner as in Example 1 except that the acid immersion time of the conductive sheet was changed to 1 minute, and the surface electrical resistance value Ra of the conductive layer of the conductive sheet was obtained in the same manner as in Example 1. , Rb, Rc, Rd were measured to calculate the rate of change CR1, CR2, and CR3 of the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Example 3)
A conductive sheet was produced in the same manner as in Example 1 except that the acid immersion time of the conductive sheet was changed to 5 minutes, and the surface electrical resistance value Ra of the conductive layer of the conductive sheet was obtained in the same manner as in Example 1. , Rb, Rc, Rd were measured to calculate the rate of change CR1, CR2, and CR3 of the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

Example 4
A conductive sheet was produced in the same manner as in Example 1 except that the acid immersion time of the conductive sheet was changed to 15 minutes. The surface electrical resistance value Ra of the conductive layer of the conductive sheet was obtained in the same manner as in Example 1. , Rb, Rc, Rd were measured to calculate the rate of change CR1, CR2, and CR3 of the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Example 5)
A conductive sheet was produced in the same manner as in Example 1 except that the acid immersion time of the conductive sheet was changed to 25 minutes, and the surface electrical resistance value Ra of the conductive layer of the conductive sheet was obtained in the same manner as in Example 1. , Rb, Rc, Rd were measured to calculate the rate of change CR1, CR2, and CR3 of the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Example 6)
A conductive sheet was prepared in the same manner as in Example 1 except that the temperature of the sulfuric acid aqueous solution was changed to 15 ° C. and the acid immersion time of the conductive sheet was changed to 5 minutes. The surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet are measured to calculate the surface electrical resistance value change rates CR1, CR2, and CR3, and the magnitude of the change in each surface electrical resistance value is evaluated. did.

(Example 7)
A conductive sheet was prepared in the same manner as in Example 1 except that the temperature of the sulfuric acid aqueous solution was changed to 40 ° C. and the acid immersion time of the conductive sheet was changed to 5 minutes. The surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet are measured to calculate the surface electrical resistance value change rates CR1, CR2, and CR3, and the magnitude of the change in each surface electrical resistance value is evaluated. did.

(Example 8)
A conductive sheet was prepared in the same manner as in Example 1 except that the concentration of the sulfuric acid aqueous solution was changed to 0.01 N, the pH was changed to 2.5, and the acid immersion time of the conductive sheet was changed to 5 minutes. 1, the surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet are measured, and the surface electrical resistance value change rates CR1, CR2, and CR3 are calculated. The magnitude of change was evaluated.

Example 9
Example 1 except that the concentration of the sulfuric acid aqueous solution was changed to 0.01 N, the pH was changed to 2.5, the temperature of the sulfuric acid aqueous solution was changed to 40 ° C., and the acid immersion time of the conductive sheet was changed to 1 minute. In the same manner as in Example 1, the surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet were measured, and the rate of change of the surface electrical resistance values CR1, CR2 And CR3 were calculated, and the magnitude of change in each surface electrical resistance value was evaluated.

(Example 10)
A conductive sheet was prepared in the same manner as in Example 1 except that the sulfuric acid aqueous solution was changed to a 0.1N hydrochloric acid aqueous solution (pH: 1.5) and the acid immersion time of the conductive sheet was changed to 1 minute. In the same manner as in Example 1, the surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet were measured, and the surface electrical resistance value change rates CR1, CR2, and CR3 were calculated. The magnitude of change in electrical resistance value was evaluated.

(Example 11)
<Preparation of paint for forming conductive layer>
The following components were added and mixed to prepare a conductive layer forming coating material b.
(1) Conductive polymer dispersion (manufactured by Heraeus, trade name “PH-1000”, conductive polymer: PEDOT-PSS, solid content concentration: 1.0 mass%, solvent: water): 13.4 parts (2) Binder resin (alkoxysilane oligomer, manufactured by Shin-Etsu Chemical Co., Ltd., trade name “X40-2308”): 0.6 part (3) Aprotic polar solvent (dimethyl sulfoxide): 15 parts (4) Protic polarity Solvent (ethanol): 64.2 parts (5) Protic polar solvent (water): 6.8 parts

<Formation of conductive sheet>
Next, a non-alkali glass (total light transmittance: 91.2%) having a size of 10 cm square and a thickness of 0.7 mm is used as a base material, and the conductive layer forming coating b is applied to one main surface of the base material. The coating was performed by spin coating for 30 seconds at a rotation speed of 1000 rpm, and then dried at 120 ° C. for 1 hour. This produced the electroconductive sheet of Example 11 in which the electroconductive layer was formed in one main surface. The thickness of the conductive layer was 0.5 μm.

<Measurement of surface electrical resistance value Ra of conductive layer immediately after production>
The surface electrical resistance value Ra of the conductive layer immediately after the production of the conductive sheet was measured using a resistivity measuring apparatus “Loresta-GP” (MCP-T610 type) manufactured by Mitsubishi Chemical Analytech Co., Ltd. and an LSP probe. As a result, Ra was 400 Ω / sq.

<Acid contact of conductive sheet>
The produced conductive sheet was cut into a 5 cm square, and the cut conductive sheet was immersed in 100 mL of sulfuric acid aqueous solution (pH: 1.5) having a temperature of 25 ° C. and a concentration of 0.1 N for 10 seconds. Thereafter, the conductive sheet was immersed in pure water for 5 seconds, washed and dried.

  Except for using the conductive sheet, the surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet were measured in the same manner as in Example 1, and the surface electrical resistance value change rate CR1, CR2 and CR3 were calculated, and the magnitude of change in each surface electrical resistance value was evaluated.

(Example 12)
A conductive sheet was produced in the same manner as in Example 1 except that the acid immersion time of the conductive sheet was changed to 3 seconds, and the surface electrical resistance value Ra of the conductive layer of the conductive sheet was obtained in the same manner as in Example 1. , Rb, Rc, Rd were measured to calculate the rate of change CR1, CR2, and CR3 of the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Example 13)
A conductive sheet was produced in the same manner as in Example 1 except that the acid immersion time of the conductive sheet was changed to 45 minutes, and the surface electrical resistance value Ra of the conductive layer of the conductive sheet was obtained in the same manner as in Example 1. , Rb, Rc, Rd were measured to calculate the rate of change CR1, CR2, and CR3 of the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Example 14)
A conductive sheet was prepared in the same manner as in Example 1 except that the temperature of the sulfuric acid aqueous solution was changed to 50 ° C. and the acid immersion time of the conductive sheet was changed to 5 minutes. The surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet are measured to calculate the surface electrical resistance value change rates CR1, CR2, and CR3, and the magnitude of the change in each surface electrical resistance value is evaluated. did.

(Example 15)
A conductive sheet was prepared in the same manner as in Example 1 except that the temperature of the sulfuric acid aqueous solution was changed to 5 ° C. and the acid immersion time of the conductive sheet was changed to 1 minute. The surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet are measured to calculate the surface electrical resistance value change rates CR1, CR2, and CR3, and the magnitude of the change in each surface electrical resistance value is evaluated. did.

(Example 16)
A conductive sheet was prepared in the same manner as in Example 1 except that the sulfuric acid aqueous solution was changed to a 0.01N acetic acid aqueous solution (pH: 3.4) and the acid immersion time of the conductive sheet was changed to 5 minutes. In the same manner as in Example 1, the surface electrical resistance values Ra, Rb, Rc, and Rd of the conductive layer of the conductive sheet were measured, and the surface electrical resistance value change rates CR1, CR2, and CR3 were calculated. The magnitude of change in electrical resistance value was evaluated.

(Comparative Example 1)
A conductive sheet was prepared in the same manner as in Example 1 except that the conductive sheet was not brought into acid contact, and the surface electricity was obtained in the same manner as in Example 1 except that this conductive sheet was not brought into acid contact. The resistance values Ra, Rc, and Rd were measured to calculate the rate of change CR2 and CR3 in the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Comparative Example 2)
A conductive sheet was prepared in the same manner as in Example 11 except that the conductive sheet was not brought into acid contact, and the surface electricity was obtained in the same manner as in Example 1 except that this conductive sheet was not brought into acid contact. The resistance values Ra, Rc, and Rd were measured to calculate the rate of change CR2 and CR3 in the surface electrical resistance value, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Comparative Example 3)
A conductive sheet was prepared in the same manner as in Example 1 except that the sulfuric acid aqueous solution was changed to pure water (pH: 7), and the pure water immersion time of the conductive sheet was changed to 5 minutes. The surface electrical resistance values Ra and Rb (surface electrical resistance values of the conductive layer after immersion in pure water), Rc and Rd are measured, and the rate of change of the surface electrical resistance values CR1, CR2 and CR3 was calculated and the magnitude of change in each surface electrical resistance value was evaluated.

(Comparative Example 4)
A conductive sheet was prepared in the same manner as in Example 1 except that the sulfuric acid aqueous solution was changed to pure water (pH: 7), and the pure water immersion time of the conductive sheet was changed to 30 minutes. The surface electrical resistance values Ra, Rb (surface electrical resistance values of the conductive layer after contact with pure water), Rc, Rd are measured, and the rate of change of the surface electrical resistance values CR1, CR2 and CR3 was calculated and the magnitude of change in each surface electrical resistance value was evaluated.

(Comparative Example 5)
A conductive sheet was produced in the same manner as in Example 1 except that the sulfuric acid aqueous solution was changed to a 0.01N sodium hydroxide aqueous solution (pH: 12.1), and the alkaline immersion time of the conductive sheet was changed to 5 minutes. In the same manner as in Example 1, the surface electrical resistance values Ra, Rb (surface electrical resistance values of the conductive layer after alkali immersion), Rc, Rd of the conductive layer of the conductive sheet were measured, and the surface electrical resistance values were measured. The change rates CR1, CR2 and CR3 were calculated, and the magnitude of the change in each surface electrical resistance value was evaluated.

(Comparative Example 6)
<Preparation of paint for forming conductive layer>
The following components were added and mixed to prepare a conductive layer forming coating material c.
(1) Conductive polymer dispersion (manufactured by Heraeus, trade name “PH-1000”, conductive polymer: PEDOT-PSS, solid content concentration: 1.0 mass%, solvent: water): 46 parts (3 ) Aprotic polar solvent (dimethyl sulfoxide): 12 parts (4) Protic polar solvent (normal propyl alcohol): 36 parts (5) Protic polar solvent (water): 6 parts

  A conductive sheet was produced in the same manner as in Example 1 except that the conductive layer-forming coating material c was used, and in the same manner as in Example 1, the surface electrical resistance values Ra, Rb, Rc and Rd were measured to calculate the rate of change of surface electrical resistance value CR1, CR2 and CR3, and the magnitude of change of each surface electrical resistance value was evaluated. The thickness of the conductive layer was 0.2 μm, and Ra was 150Ω / sq.

  The evaluation results of Examples 1 to 16 and Comparative Examples 1 to 6 are shown in Tables 1 to 3. Tables 1 to 3 also show the type of conductive layer forming paint used and the surface treatment conditions of the conductive sheet.

  From Tables 1 and 2, in Examples 1 to 11 of the present invention, the change rates RC1, RC2, and RC3 of the surface electrical resistance values were all excellent (A). In Example 12 in which the immersion time was less than 5 seconds, Example 15 in which the temperature of the treatment liquid was less than 10 ° C., and Example 16 in which the pH of the treatment liquid was 3 or more, the effect of the acid treatment was high. The change rate RC1 of the surface electrical resistance value was excellent (A) because of a slight decrease, but only good (B) in RC2 and RC3. Further, in Example 13 in which the immersion time exceeded 30 minutes and in Example 15 in which the temperature of the treatment liquid exceeded 45 ° C., the rate of change in surface electrical resistance value RC1, RC2 was probably due to the effect of acid treatment being slightly too strong. All of RC3 remained good (B).

  On the other hand, from Comparative Example 1 and 2 in which acid treatment was not performed from Table 3, the rate of change RC2 and RC3 of the surface electrical resistance value was poor (C), and in Comparative Example 3 where the immersion time of pure water was 5 minutes, Although the rate of change RC1 of the surface electrical resistance value was good (B), the rate of change RC2 and RC3 of the surface electrical resistance value was poor (C), and the immersion time for pure water was 30 minutes in Comparative Example 4, alkali treatment In Comparative Example 4 performed and Comparative Example 6 using the conductive layer forming paint not including the binder resin, all of the change rates RC1, RC2, and RC3 of the surface electrical resistance value were defective (C).

10 conductive sheet 11 base material 12 conductive layer

Claims (6)

A method for producing a conductive sheet comprising a base material and a conductive layer disposed on at least one main surface of the base material,
A paint preparation process for preparing a conductive layer-forming paint comprising a conductive polymer, a binder resin, and a solvent;
A conductive layer forming step of forming a conductive layer on the substrate by applying and drying the conductive layer forming paint on the substrate; and
An acid contact step of contacting the conductive layer with an acidic aqueous solution,
The said binder resin is a fluorine resin or a silicone resin, The manufacturing method of the electroconductive sheet characterized by the above-mentioned.   The method for producing a conductive sheet according to claim 1, wherein the conductive polymer includes a polythiophene compound and polystyrene sulfonic acid. In the acid contact step,
The pH of the acidic aqueous solution is less than 3,
The temperature of the acidic aqueous solution is 10 ° C. or higher and 45 ° C. or lower,
The method for producing a conductive sheet according to claim 1 or 2, wherein the acidic aqueous solution is brought into contact with the conductive layer for 5 seconds to 30 minutes.   The conductivity according to any one of claims 1 to 3, wherein the acid contained in the acidic aqueous solution is at least one selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid and hydroiodic acid. Sheet manufacturing method.   The content of the binder resin in the coating material for forming a conductive layer is 30.0% by mass or more and 99.3% by mass or less with respect to the total mass of the conductive polymer and the binder resin. 5. The method for producing a conductive sheet according to any one of 4 above.   The said solvent contains the protic polar solvent and the aprotic polar solvent, The manufacturing method of the electroconductive sheet of any one of Claims 1-5.

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