JP5178265B2 - Conductive film and touch panel using the same - Google Patents

Description

  The present invention relates to a conductive film and a touch panel using the same. More specifically, the present invention relates to a conductive film excellent in adhesion between a base film and a transparent conductive coating film layer and moisture and heat resistance, and a touch panel excellent in moisture and heat resistance using the same.

Conventionally, a transparent conductive film is suitably used as a material that requires transparency and conductivity, such as an electrode in a liquid crystal display or a touch panel, or an electromagnetic shielding material. Such a transparent conductive film is obtained, for example, by forming a transparent conductive layer on at least one surface of a transparent substrate film such as polyethylene terephthalate (PET) or triacetyl cellulose (TAC) by a dry process or a wet process. The dry process refers to indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), In ₂ O ₃ and SnO ₂ on the transparent substrate film by vacuum deposition, sputtering, ion plating, or the like. And forming a transparent conductive layer made of a mixed sintered body (ITO) or the like. On the other hand, the wet process is a method of forming a transparent conductive layer by applying a liquid containing a conductive polymer or conductive inorganic particles on the transparent base film using various coaters. Today, a transparent conductive film obtained by a wet process is often used from the viewpoints that the conductive layer itself is flexible and hardly causes problems such as cracks, is relatively inexpensive to manufacture, and is excellent in productivity. It has been. In particular, from the viewpoint of excellent transparency and conductivity, a transparent conductive film using a conductive polymer containing polythiophene as described in Patent Documents 1 to 3 is often used.

  In recent years, studies have been made on improving the water resistance of a transparent conductive film using the above-described conductive polymer.

Japanese Patent Laid-Open No. 1-313521 JP 2002-193972 A JP 2003-286336 A JP 2005-281704 A

  However, since the transparent conductive film disclosed in Patent Documents 1 to 3 includes a highly hydrophilic polyanion as a constituent component, the resulting transparent conductive layer has low heat-and-moisture resistance and is in a high-temperature and high-humidity environment. When exposed, it has the disadvantage of a significant decrease in conductivity. For example, when this is used as an electrode of a touch panel, there is a problem of causing malfunction in a high-temperature and high-humidity environment, and improvement is required.

In addition, the transparent conductive film disclosed in Patent Document 4 has recently been requested because of the high hydrophilicity of the self-emulsifying polyester resin or the low heat resistance of the self-emulsifying polyester resin. It does not satisfy moisture and heat resistance. Further, depending on the dispersion state of the self-emulsifying polyester resin, there is a problem that uniform water resistance and conductivity cannot be obtained.
Furthermore, the transparent conductive layer in the above Patent Documents 1 to 4 has low adhesion and low coating strength, which causes a problem that the transparent conductive layer is scraped or peeled off during the processing step or during product use.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is not only excellent in transparency and conductivity, but in particular, adhesion between the base film and the transparent conductive coating layer, and moisture resistance. It is providing the electroconductive film excellent in heat property. Another object of the present invention is to provide a touch panel excellent in durability and heat and moisture resistance.

  The present inventors have intensively studied to solve the above problems. As a result, as a transparent conductive coating layer, together with a conductive polymer containing cationic polythiophene and polyanion, a silane compound having an epoxycyclohydrocarbon group, and a water-soluble polyester having a hydroxyl group or a carboxyl group at least at the terminal or side chain The present inventors have found that a conductive film excellent in adhesion and heat-and-moisture resistance can be obtained by forming a coating film containing as a constituent component.

That is, the present invention provides at least one side of the base film,
(I) a conductive polymer (A) comprising a cationic polythiophene containing a repeating unit represented by the following formula (I) as a main component and a polyanion;
(Ii) Silane compound (B) having an epoxycyclohydrocarbon group of 0.5 to 9 parts by mass with respect to 100 parts by mass of the conductive polymer, and (iii) 100 parts by mass of the conductive polymer. In contrast, the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at a terminal or a side chain of 10 parts by weight to 70 parts by weight.
It is the electroconductive film by which the transparent conductive coating film layer containing as a structural component was laminated | stacked.

(In formula (I), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or may be optionally substituted together. Represents an alkylene group having 1 to 12 carbon atoms.)

Furthermore, the present invention is such that the rate of change in surface resistance before and after 240 hours treatment at 60 ° C. and 90% relative humidity is 120% or less, and contact resistance before and after 240 hours treatment at 60 ° C. and 90% relative humidity. the value change of not more than 150%, the surface of the transparent conductive coating layer side of the conductive film, Gakushin abrasion testing machine was used to the 10 mm ² impregnated with ion-exchanged water as a rubbing portion gauze (Convallaria Made by Co., Ltd., using 40 yarns of cotton yarn, which are struck in 12 cm length and width in a 1 cm square), and rubbed 5 times under the conditions of a load of 700 g and a speed of 1 reciprocation / 2 seconds. but it remains more than 60% by area, the total light transmittance is not less than 80%, of the surface resistance value is 10 [Omega / □ or more 1 × 10 ⁵ Ω / □ or less, at least one of the aspect By including, it is possible to obtain a further excellent conductivity film.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive film excellent in the adhesiveness of a base film and a transparent conductive coating film layer and excellent in heat-and-moisture resistance can be provided. Furthermore, the conductive film of the present invention has excellent conductivity equivalent to that of a conductive film laminated with ITO while using a conductive polymer, and also has excellent transparency. Therefore, the conductive film of the present invention can be suitably used as a transparent electrode such as a liquid crystal display, a touch panel, an organic electroluminescence element, an inorganic electroluminescence lamp, and electronic paper, and particularly has excellent adhesion and heat and humidity resistance. This is extremely useful in the field of highly demanded resistive touch panels.

  Moreover, in this invention, a uniform coating film layer can be obtained even if it does not use a dispersing agent in the coating liquid for forming a transparent conductive coating film layer. Therefore, the coating liquid preparation process can be simplified and uniform conductivity can be expressed.

<Conductive film>
The conductive film of the present invention is a conductive film in which a transparent conductive coating layer described later is laminated on at least one side of a substrate film described later.

  If the conductive film of this invention is an aspect containing a base film and a transparent conductive coating film layer, it will not specifically limit about another layer. In the case of including other layers, for example, for the purpose of improving adhesion and the like, in the case of having an anchor coat layer or the like between the base film and the transparent conductive coating film layer, or for the purpose of protecting the surface, The case where it has protective films, such as a hard-coat layer, on a base film is mentioned. Moreover, when the transparent conductive coating layer is provided on one side of the base film, the remaining one side can be provided with a layer such as an adhesive layer, an anchor coat layer, a hard coat layer, etc., if necessary. .

Below, each structural component and characteristic of the electroconductive film of this invention are demonstrated.
<Transparent conductive coating layer>
The transparent conductive coating layer in the present invention comprises a conductive polymer (A) containing a cationic polythiophene and a polyanion, a silane compound (B) having an epoxycyclohydrocarbon group, and at least a terminal or a side chain with a hydroxyl group or a carboxyl group. The water-soluble polyester (C) having a group is contained as an essential component. Hereinafter, each component of the transparent conductive coating layer will be described.

(Conductive polymer (A))
The conductive polymer (A), which is an essential constituent of the transparent conductive coating layer in the present invention, contains cationic polythiophene and polyanion as essential constituents. The method for producing the conductive polymer used in the present invention is not particularly limited. For example, it can be obtained by oxidative polymerization of a substance that becomes a cationic polythiophene monomer in an aqueous polyanion solution. .

The cationic polythiophene in the present invention contains 3,4-disubstituted thiophene represented by the following formula (I) as a main component of the repeating unit.

Here, in the above formula (I), R ¹ and R ² are, independently of one another, represent a hydrogen atom or having 1 to 4 alkyl group having a carbon. Alternatively, R ¹ and R ² together represent an optionally substituted alkylene group having 1 to 12 carbon atoms. When R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ¹ and R ² may be a methyl group, an ethyl group, a propyl group, or a butyl group. Are preferable, and a methyl group and an ethyl group are particularly preferable. In the case where R ¹ and R ² together are an optionally substituted alkylene group having 1 to 12 carbon atoms, examples of the alkylene group having 1 to 12 carbon atoms include methylene And alkylene groups such as 1,2-ethylene group, 1,2-propylene group, 1,3-propylene group, 1,4-butylene group, 2,3-butylene group and 1,2-cyclohexylene group. It is done. Of these, α, β-alkylene groups such as a methylene group, 1,2-ethylene group, 1,2-propylene group, and 2,3-butylene group are particularly preferable. Examples of such α, β-alkylene groups are derived from 1,2-dibromoalkanes obtained by bromination of α-olefins such as ethene, propene, hexene, octene, decene, dodecene, and styrene. Can do. Moreover, as a substituent in the said alkylene group, a C1-C12 alkyl group and a phenyl group are preferable, and especially a methyl group, an ethyl group, and a propyl group are preferable.

  The cationic polythiophene in the present invention may contain only 3,4-disubstituted thiophene represented by the above formula (I) as a repeating unit, or 3,4-disubstituted thiophene as a main component of the repeating unit. And other monomers that can be polymerized therewith as secondary components. Here, the “main component” means that the proportion of the repeating unit of the 3,4-disubstituted thiophene represented by the above formula (I) is 50 mol% with respect to the entire repeating unit constituting the cationic polythiophene. It means a large range of 100 mol%.

  The polythiophene as described above exhibits a cationic property. Such cationic polythiophene can be obtained, for example, by oxidative polymerization of 3,4-disubstituted thiophene, which is a monomer, by the method described in JP-A-1-313521.

  The polyanion in the present invention is not particularly limited. Examples thereof include polymeric carboxylic acids such as polyacrylic acid, polymethacrylic acid, and polymaleic acid, and polymeric sulfonic acids such as polystyrene sulfonic acid and polyvinyl sulfonic acid.

  Such polyanions such as polymeric carboxylic acids and polymeric sulfonic acids may be homopolymers composed of only one type of anionic monomer, or may be copolymers composed of a plurality of types of anionic monomers. Further, it may be a copolymer of an anionic monomer and other monomers copolymerizable with the monomer. Examples of other monomers copolymerizable with an anionic monomer include acrylates and styrenes. When the polyanion is a copolymer, it is sufficient that at least one anionic monomer is contained as a copolymerization component.

Among these, as the polyanion in the present invention, polystyrene sulfonic acid and polystyrene sulfonic acid at least part of which is a metal salt are particularly preferable and are excellent in the effect of improving conductivity.
The number average molecular weight Mn of the polyanion is preferably in the range of 1,000 to 2,000,000, and more preferably in the range of 2,000 to 500,000.

(Silane compound having epoxycyclohydrocarbon group (B))
In the present invention, the transparent conductive coating layer contains the silane compound (B) having an epoxycyclohydrocarbon group as an essential component, and the silane compound (B) has an epoxycyclohydrocarbon group in the transparent conductive coating layer. By making content into a specific numerical range, the electroconductive film excellent in heat-and-moisture resistance and coating-film intensity | strength can be obtained.

The silane compound (B) having such an epoxycyclohydrocarbon group is a compound represented by the following formula (II).

  X in the above formula (II) represents a hydrolyzable functional group selected from an alkoxy group, an acyloxy group, and a halogen, or a hydrocarbon group. Of these, an alkoxy group and an acyloxy group are preferable. The alkoxy group is preferably an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkoxy group having 1 to 6 carbon atoms. Specifically, a methoxy group, an ethoxy group, a propoxy group, a methoxymethoxy group, a methoxyethoxy group, an ethoxymethoxy group, and an ethoxyethoxy group are preferable, and a methoxy group and an ethoxy group are particularly preferable. As the acyloxy group, an acyloxy group having 2 to 11 carbon atoms is preferable, an acyloxy group having 2 to 7 carbon atoms is more preferable, and an acetoxy group is particularly preferable. As the halogen, a chloro group is preferable. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an allyl group, and a hydrocarbon group that may have an epoxy group, an amino group, a mercapto group, a methacryl group, or a cyano group.

  Y in the above formula (II) represents a functional group having an epoxycyclohydrocarbon group. In the present invention, the epoxycyclohydrocarbon group refers to an epoxycycloalkane group, an epoxycycloalkene group, and an epoxycycloalkyne group. Of these, an epoxycycloalkane group is preferable. The epoxycycloalkane group is preferably an epoxycycloalkane group having 3 to 12 carbon atoms. Such an epoxycycloalkane group having 3 to 12 carbon atoms is preferably an epoxycyclopentyl group, an epoxycyclohexyl group, an epoxycycloheptyl group, or an epoxycyclooctyl group, and particularly preferably an epoxycyclohexyl group. When Y in the formula (II) is in the above-described manner, the effect of improving the heat and moisture resistance can be increased.

  In the above formula (II), such an epoxycyclohydrocarbon group is bonded to a silicon atom Si through an alkylene group or the like. Such an alkylene group is preferably a linear or branched alkylene group having 1 to 12 carbon atoms. Of these, a methylene group, an ethylene group, and a propylene group are particularly preferable. The alkylene group as described above may have an ether bond or an amino bond in the chain of the alkylene group.

  N in the above formula (II) represents an integer of 1 to 3. n is preferably 1 or 2, and particularly preferably 1. That is, at least one X may be bonded to the silicon atom Si in the above formula (II), but an embodiment in which two or three X are bonded is preferable. It is excellent in coating-film intensity | strength as it is the above aspects, and it can make the improvement effect of heat-and-moisture resistance high. When a plurality of Xs are bonded to the silicon atom Si, the plurality of Xs may all be the same type of functional groups, or different types of functional groups may be mixed.

  Specific examples of the silane compound (B) having an epoxycyclohydrocarbon group as described above include, for example, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl. A preferred example is triethoxysilane.

  Moreover, in this invention, it is also possible to use a commercial item as it is as a silane compound (B) which has an epoxycyclo hydrocarbon group. Examples of the commercially available silane compound (B) having an epoxycyclohydrocarbon group include Momentive Performance Materials Japan G.K., trade name: A-186, or trade name: Coatsil (registered trademark) 1770. is there.

  Content of the silane compound (B) which has an epoxycyclohydrocarbon group in a transparent conductive coating film layer is 0.5 mass part or more and 9 mass parts or less with respect to 100 mass parts of conductive polymers. By making content of the silane compound (B) which has an epoxycyclohydrocarbon group into the said numerical range, the heat-and-moisture resistance and adhesiveness of a transparent conductive coating film layer can be made favorable. When the content is too small, not only the heat and moisture resistance is inferior, but also the adhesion to the base film tends to be low, and the coating film is easily peeled off. On the other hand, if the content is too large, there is a problem and the heat and humidity resistance is poor. From such a viewpoint, the content is more preferably 0.8 parts by mass or more and 8 parts by mass or less, and particularly preferably 1 part by mass or more and 6 parts by mass or less. Here, “with respect to 100 parts by mass of the conductive polymer” means “with respect to 100 parts by mass of the solid content of the conductive polymer”.

(Water-soluble polyester (C))
In the present invention, the transparent conductive coating layer contains at least the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at the terminal or side chain as an essential component, and the water-soluble polyester (C) in the transparent conductive coating layer By making content into a specific numerical range, the electroconductive film excellent in the adhesiveness of a base film and a transparent conductive coating film layer, coating-film intensity | strength, and heat-and-moisture resistance can be obtained.

  Such water-soluble polyester (C) has a hydroxyl group, a carboxyl group, or both of them. The total content of hydroxyl groups and carboxyl groups is preferably 0.1 mol% or more and 40 mol% or less, more preferably 1 mol% or more and 20 mol%, based on 100 mol% of the total acid component of the water-soluble polyester (C). It is as follows. The hydroxyl group or carboxyl group may be at both the terminal or side chain, or may be at either one. Moreover, the number is not limited. In the present invention, “water-soluble” refers to a substance that is soluble in methanol containing 50% or more (volume%) of water.

The water-soluble polyester (C) in the present invention preferably includes a sulfonate group. Examples of the sulfonate group include alkali metal bases of sulfonate represented by —SO ₃ Na and —SO ₃ K. The content of the sulfonate group in the water-soluble polyester (C) is preferably 1 mol% or more and 10 mol% or less, more preferably 2 mol% or more with respect to 100 mol% of the total acid component of the water-soluble polyester (C). It is 7 mol% or less, particularly preferably 2 mol% or more and 4 mol% or less. When the content of the sulfonate group is in the above numerical range, the effect of improving the adhesion, the coating film strength, and the heat and humidity resistance tends to be increased. The water-soluble polyester (C) has an acid component of 50 to 95 mol% of terephthalic acid, 3 to 43 mol% of isophthalic acid, and 2 to 7 mol% of 5-sulfoisophthalic acid. An acid alkali metal salt is preferably contained, and the acid component is 50 to 95 mol% of terephthalic acid, 3 to 46 mol% of isophthalic acid, and 2 to 4 mol% of 5 -It is particularly preferred to contain alkali metal sulfoisophthalic acid salts.

  The weight average molecular weight Mw of the water-soluble polyester (C) as described above is preferably 1,000 or more and 100,000 or less, more preferably 5,000 or more and 30,000 or less. When the weight average molecular weight Mw is in the above numerical range, the effect of improving the adhesion between the transparent conductive coating layer and the substrate film and the effect of improving the strength of the transparent conductive coating layer can be increased.

  Moreover, in this invention, it is also possible to use a commercial item as it is as water-soluble polyester (C). Examples of commercially available water-soluble polyesters (C) include trade names: Plus Coat RZ-570, Z-565, Z-561, Z-658, etc., manufactured by Kyoyo Chemical Co., Ltd.

  Content of water-soluble polyester (C) in a transparent conductive coating film is 10 to 70 mass parts with respect to 100 mass parts of conductive polymers. By making content of water-soluble polyester (C) into the said numerical range, the adhesiveness of a base film and a transparent conductive coating film layer can be made favorable. Moreover, the intensity | strength of a transparent conductive coating film layer can be made high. Furthermore, the heat and moisture resistance can be improved. When there is too little content of water-soluble polyester (C), it will be inferior to adhesiveness and coating-film intensity | strength. Moreover, it becomes inferior to heat-and-moisture resistance. On the other hand, when there is too much content, it exists in the tendency for electroconductivity and transparency to become low. Also, it tends to be inferior in heat and humidity resistance. From such a viewpoint, the content is more preferably 15 parts by mass or more and 60 parts by mass or less, and particularly preferably 20 parts by mass or more and 40 parts by mass or less. Here, “with respect to 100 parts by mass of the conductive polymer” means “with respect to 100 parts by mass of the solid content of the conductive polymer”.

(Other components contained in the transparent conductive coating layer)
The transparent conductive coating layer according to the present invention comprises a conductive polymer (A) containing the above cationic polythiophene and polyanion, a silane compound (B) having an epoxycyclohydrocarbon group, and at least a terminal or a side chain. In addition to the water-soluble polyester (C) having a hydroxyl group or a carboxyl group, other components may optionally be included for the purpose of improving the performance of the transparent conductive coating layer, such as improving conductivity. . Hereinafter, arbitrary components will be described.

  The transparent conductive coating layer in the present invention can contain diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol and the like from the viewpoint of improving conductivity. In addition, it can contain a water-soluble compound having an amide bond in the molecule and liquid at room temperature.

  The content of these compounds is preferably 10 parts by mass or more and 1000 parts by mass or less, and more preferably 30 parts by mass or more and 600 parts by mass or less with respect to 100 parts by mass of the conductive polymer. When the content is too small, the effect of improving the conductive performance tends to be low, and the surface resistance value hardly decreases. On the other hand, when there is too much content, it exists in the tendency which is inferior to transparency, adhesiveness, and blocking resistance. Moreover, it exists in the tendency for the improvement effect of the heat-and-moisture resistance of a transparent conductive coating layer to become low. Here, “with respect to 100 parts by mass of the conductive polymer” means “with respect to 100 parts by mass of the solid content of the conductive polymer” as described above.

  In addition, the transparent conductive coating layer in the present invention has an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, an organic lubricant, a pigment, a dye, and the like within a range that does not impair the effects of the present invention. Organic or inorganic fine particles, fillers, transparent conductive agents, nucleating agents and the like may be blended.

(Coating composition (coating material) for forming transparent conductive coating layer)
The transparent conductive coating film layer in the present invention is a coating composition for forming a transparent conductive coating film layer (hereinafter sometimes referred to as a coating agent) on a layer on which the transparent conductive coating film layer is to be formed. It is formed by applying and drying. Here, as the coating agent, the conductive polymer (A) containing the cationic polythiophene and the polyanion, the silane compound (B) having an epoxycyclohydrocarbon group, a hydroxyl group or a carboxyl group at least at a terminal or a side chain Water-soluble polyester (C) having water, an optional component for improving the performance of the transparent conductive coating layer, and an aqueous dispersion in which an optional component for improving the performance of the coating agent described later is dispersed in water .

  Examples of the optional component for improving the performance of the coating agent include a solvent and a surfactant. Hereinafter, optional components for improving the performance of the coating agent will be described.

  In the coating material in the present invention, for the purpose of dissolving each component constituting the transparent conductive coating film layer, for the purpose of improving the wettability to the base film, or for the coating material For the purpose of adjusting the solid content concentration or the like, an appropriate solvent compatible with water as a dispersion medium can be added within a range allowed by the drying step. Examples of such a solvent include methanol, ethanol, 2-propanol, n-propanol, isobutanol, ethylene glycol, acetone, acetonitrile, tetrahydrofuran, dioxane, and mixed solvents thereof.

  Moreover, a small amount of surfactant can be added to the coating agent in the present invention for the purpose of improving the wettability with respect to the base film. Preferred surfactants include, for example, nonionic surfactants such as polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, sorbitan fatty acid ester, fluoroalkyl carboxylate, perfluoroalkylbenzene sulfonate, and perfluoroalkyl. Fluorosurfactants such as quaternary ammonium salts and perfluoroalkyl polyoxyethylene ethanol can be mentioned.

  The method for producing the coating agent is not particularly limited as long as the components constituting the transparent conductive coating layer are dispersed in water. For example, the method which mixes each component which comprises a coating agent under stirring can be mentioned. In particular, if the components are dispersed while being subjected to ultrasonic treatment, each component can be more evenly dispersed.

(Method for producing transparent conductive coating layer)
As described above, the transparent conductive coating film layer in the present invention is formed by applying the coating agent on a layer on which the transparent conductive coating film layer is to be formed and drying it. The coating method of the coating agent is not particularly limited, and a known method can be adopted. For example, lip direct method, comma coater method, slit reverse method, die coater method, gravure roll coater method, roll coater method, blade coater method, spray coater method, air knife coat method, dip coat method, bar coater method, etc. It can be mentioned as a preferred method.

  The drying conditions for obtaining the transparent conductive coating layer are not particularly limited, but it is preferable to dry for 10 seconds to 300 seconds in a temperature range of 80 ° C. or higher and 160 ° C. or lower, and 100 ° C. or higher and 150 ° C. or higher. It is particularly preferable to dry in the temperature range of not higher than 20 ° C. for 20 seconds to 120 seconds.

(Thickness and arrangement of transparent conductive coating layer)
As for the film thickness of the transparent conductive coating layer in this invention, 20 nm or more and 300 nm or less are preferable. By making a film thickness into the said numerical range, the improvement effect of electroconductivity, transparency, and heat-and-moisture resistance can be made high. When the film thickness of a transparent conductive coating film layer is too thick, it exists in the tendency for the transparency of a transparent conductive coating film layer to fall, and in the conductive film obtained, the transparency improvement effect becomes low. On the other hand, when it is too thin, the surface resistance value tends to be high, and in the obtained conductive film, the effect of improving the conductivity is low. From such a viewpoint, the film thickness is preferably 30 nm or more and 200 nm or less.

  In addition, it does not specifically limit as a method of controlling the film thickness of a transparent conductive coating film layer. For example, the film thickness can be controlled by appropriately controlling the solid content concentration and coating amount of the coating agent according to the coating method to be carried out.

  The conductive film of the present invention has a transparent conductive coating film layer formed on at least one side of a base film described later, but may be an embodiment in which only one transparent conductive coating layer is formed. And the aspect in which the above-mentioned transparent conductive coating film layer is formed in multiple layers may be sufficient, or the aspect in which the other conductive layer different from the above-mentioned transparent conductive coating film layer is formed may be sufficient. . Examples of such other conductive layers include other conductive coating films different from the above-described transparent conductive coating layer, and conductive films obtained by a dry process such as ITO.

  Here, when a plurality of transparent conductive coating layers are formed, or when another conductive layer different from the transparent conductive coating layer is formed, the total thickness is 20 nm or more and 300 nm or less. It is preferably 30 nm to 200 nm, more preferably 50 nm to 200 nm. If the overall thickness is too thin, the conductivity tends to be low. On the other hand, if it is too thick, it tends to be inferior in transparency and blocking resistance.

  Moreover, it is preferable that a transparent conductive coating film layer is an outermost layer with respect to a base film in a conductive film. By setting it as such an aspect, the electrical conductivity improvement effect can be made high.

<Base film>
The base film in the present invention is not particularly limited, and examples thereof include polyester, polystyrene, polyimide, polyamide, polysulfone, polycarbonate, polyvinyl chloride, polyethylene, polypropylene, and blends and copolymers thereof, and phenol. A sheet, a film, or a nonwoven fabric made of a resin, an epoxy resin, an ABS resin, or the like can be given.

  Among them, a biaxially oriented polyester film can be preferably used from the viewpoint of excellent mechanical properties, dimensional stability, heat resistance, electrical properties, etc., and in particular, mechanical properties, heat resistance, dimensional stability. Since it is excellent, a polyethylene terephthalate film or a polyethylene-2,6-naphthalate film is particularly preferable.

  The thickness of the base film is not particularly limited, but is preferably 500 μm or less. If it is thicker than 500 μm, the rigidity of the base film is too high, and the handling property tends to be poor when the conductive film is attached to a display or the like.

  Further, the base film can be subjected to a preliminary treatment on the film surface as necessary for the purpose of improving adhesion, coating property and the like before applying the coating agent. Examples of such preliminary treatment include physical surface treatment such as corona discharge treatment and plasma discharge treatment, or coating of an organic resin or inorganic resin during or after film formation, And a chemical surface treatment for forming.

<Characteristics of conductive film>
(Total light transmittance)
The conductive film of the present invention preferably has a total light transmittance of 80% or more. When the total light transmittance is in the above numerical range, a touch panel having excellent transparency can be obtained. From such a viewpoint, the total light transmittance is more preferably 83% or more, further preferably 85% or more, and particularly preferably 87% or more.

  In addition, in order to make a total light transmittance into the said numerical range, it is achieved by adjusting the film thickness of a transparent conductive coating film layer. It is also achieved by adjusting the type and content of the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at the terminal or side chain.

(Surface resistance value)
The conductive film of the present invention preferably has a surface resistance value of 10Ω / □ or more and 1 × 10 ⁵ Ω / □ or less. By making the surface resistance value in the above numerical range, it is excellent in conductivity. For example, when used for a touch panel, excellent writing property is easily obtained. If the surface resistance value is too high, the conductivity tends to be inferior, and the touch panel is difficult to operate, such as being unable to write even if touched. On the other hand, in order to make the surface resistance value less than 10Ω / □, it is necessary to increase the amount of the conductive polymer used or to increase the film thickness of the transparent conductive coating layer, resulting in an increase in manufacturing cost and economy. Disadvantageous, and the effect of improving transparency tends to be low.

  In addition, in order to make a surface resistance value into the said numerical range, it is achieved by adjusting the film thickness of a transparent conductive coating film layer. Moreover, it is achieved by adjusting the kind and content of the conductive polymer and the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at the terminal or side chain.

(Surface resistance value change rate)
The conductive film of the present invention preferably has a surface resistance value change rate of 120% or less before and after being treated at 60 ° C. and 90% relative humidity for 240 hours. The rate of change of the surface resistance value is more preferably 115% or less, and particularly preferably 110% or less. When the rate of change of the surface resistance value is too high, it tends to be likely to malfunction when used as an electrode of a resistive touch panel and when the resistive touch panel is exposed to a high temperature and high humidity environment.

  In addition, in order to make a surface resistance value change rate into the said numerical range, it achieved by adjusting suitably the kind of silane compound compound (B) which has an epoxycyclohydrocarbon group contained in a transparent conductive coating film layer, and content. Is done. It is also achieved by appropriately adjusting the type and content of the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at the terminal or side chain.

(Contact resistance value change rate)
The conductive film of the present invention preferably has a contact resistance value change rate of 150% or less before and after being treated at 60 ° C. and 90% relative humidity for 240 hours. The contact resistance value change rate is more preferably 140% or less, and particularly preferably 130% or less. When the contact resistance value change rate is too high, it is used as a resistive film type touch panel electrode, and when the resistive film type touch panel is exposed to a high temperature and high humidity environment, the response of the touch panel becomes dull and does not operate smoothly. It tends to be inferior to writing.

  In addition, in order to make a contact resistance value change rate into the said numerical range, it achieved by adjusting suitably the kind and content of the silane compound compound (B) which have an epoxycyclohydrocarbon group contained in a transparent conductive coating film layer. Is done. It is also achieved by appropriately adjusting the type and content of the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at the terminal or side chain.

(Adhesion and strength of transparent conductive coating layer)
The conductive film of the present invention preferably satisfies the following aspects with respect to the adhesion and strength of the transparent conductive coating film layer. That is, the surface on the transparent conductive coating layer side of the conductive film is subjected to ion exchange water as a rubbing part using a Gakushin abrasion tester (trade name: Gakushin type friction fastness tester manufactured by Tester Sangyo Co., Ltd.). Using impregnated 10 mm ² gauze (made by Suzuran Co., Ltd., cotton yarn No. 40 threaded in 12 cm length and width in 1 cm square), rubbing 5 times under conditions of load 700 g, speed 1 reciprocation / 2 seconds, It is preferable that the state of the transparent conductive coating layer in the rubbed portion is visually evaluated, and the transparent conductive coating layer in the rubbed portion remains 60% or more in area. The transparent conductive coating layer is more preferably 70% or more, and particularly preferably 80% or more. With such an embodiment, the adhesion between the film substrate and the transparent conductive coating film layer is higher, and the strength of the transparent conductive coating layer is higher, so that a touch panel with further durability can be obtained. it can.

  In addition, in order to set it as the above aspects, it is achieved by adjusting suitably the kind of silane compound compound (B) which has an epoxycyclo hydrocarbon group contained in a transparent conductive coating film layer, and content. It is also achieved by appropriately adjusting the type and content of the water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at the terminal or side chain.

<Touch panel>
The touch panel of the present invention is formed by arranging a pair of electrodes having a conductive layer so that the conductive layers face each other with a spacer interposed therebetween. Here, the conductive film of the present invention is applied to at least one of the electrodes. It is what is used. In addition, before the opposing arrangement | positioning, the circuit is previously formed in the conductive layer of both electrodes.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. In Examples and Comparative Examples, each measurement was performed by the following method.

(1) Surface resistance value It measured based on JISK7194 using Mitsubishi Chemical Corporation make and brand name: Lorester MCP-T600. The measurement was carried out at five arbitrary positions on each of the three sample pieces, and the average value thereof was defined as the surface resistance value (unit: Ω / □).

(2) Surface resistance value after wet heat treatment and rate of change in surface resistance value Store the sample in a constant temperature and humidity oven at a temperature of 60 ° C. and a relative humidity of 90%, and take out the sample when 240 hours have passed continuously, After the sample temperature returned to room temperature, the surface resistance value was measured in the same manner as in the above method (1). The measurement was performed for each of five arbitrary locations of the three sample pieces, and the average value thereof was defined as the surface resistance value after wet heat treatment (unit: Ω / □).

Moreover, the surface resistance value change rate (unit:%) was calculated | required by the following formula | equation from the surface resistance value before and behind the wet heat processing obtained by the above method.

(3) Contact resistance value A simple touch panel as shown in FIG. 1 is prepared, and the vicinity of the center of the simple touch panel is pressed by using a polyacetal pen whose pen point is a semicircle with a diameter of 0.8 mm. The electrode and the lower electrode were brought into contact. The pressing was performed with a constant load of 50 g. The resistance value 1 minute after contact was read and used as the measured value. Each of the three samples was measured nine times in the plane, and the average value thereof was defined as the contact resistance value (unit: kΩ).

(4) Contact resistance value after wet heat treatment and rate of change in contact resistance value The simple touch panel obtained in (3) above is stored in a constant temperature and humidity oven at a temperature of 60 ° C. and a relative humidity of 90%. Removed when time passed. After the sample temperature returned to room temperature, the contact resistance value was measured in the same manner as in the method (3) above. Each of the three samples was measured nine times in-plane, and the average value thereof was defined as the contact resistance value (unit: kΩ) after the wet heat treatment.

Moreover, the contact resistance value change rate (unit:%) was calculated | required by the following formula | equation from the contact resistance value before and behind the wet heat processing obtained by the above method.

(5) Total light transmittance Measured according to JIS K7150 using a haze meter (trade name: HCM-2B) manufactured by Suga Test Instruments. In measurement, it implemented about arbitrary 5 places of a sample (electroconductive film), and made those average values the total light transmittance (unit:%).

(6) Adhesion and strength (residual rate) of transparent conductive coating layer
Measurement was carried out using a Gakushoku abrasion tester (trade name: Gakushin type friction fastness tester manufactured by Tester Sangyo Co., Ltd.). Specifically, a 10 mm ² gauze impregnated with ion-exchanged water as a rubbing part (manufactured by Suzuran Co., Ltd., cotton yarn No. 40 was struck in a length of 12 cm vertically and 12 by 1 cm square), load 700 g, speed 1 The surface of the conductive film on the transparent conductive coating layer side was rubbed for 5 reciprocations under the condition of reciprocation / 2 seconds. Next, the area of the portion where the transparent conductive coating layer remained in the rubbed portion was determined. The ratio of the area of the portion where the transparent conductive coating film layer remained to the area of the rubbed portion was calculated, and was defined as the residual ratio of the transparent conductive coating layer (unit:%). It shows that it is excellent in the adhesiveness of a base film and a transparent conductive coating layer, and the intensity | strength of a transparent conductive coating layer is so high that a residual rate is high.

(7) Weight average molecular weight Mw, number average molecular weight Mn
1 mg of a resin sample (solid content) is dissolved in 0.5 ml of hexafluoroisopropanol, chloroform is added to make 10 ml (concentration 0.01 w / v%), and the solution filtered through a membrane filter 0.45 μm is used as a measurement solution. It was measured by permeation chromatography (GPC). The measurement apparatus and measurement conditions in the measurement were as follows.

[measuring device]
Body: TOSOH HLC-8020
Detector: Built-in main body (differential refractometer), TOSOH UV-8011 (ultraviolet absorption detector)
Column: TOSOH TSK-gel GMHHR-H, TOSOH TSK-gel GMHHR-N, TOSOH TSK-gel G2000H
Data processor: TOSOH SC-8020
[Measurement condition]
Mobile phase: Chloroform flow rate: 1.0 ml / min
Column temperature: 40 ° C
Detector: UV (254 nm)
Injection volume: 200 μl
Standard sample: Polystyrene (manufactured by Polymer Laboratories, trade name: EasiCal “PS-1”)

<Aqueous dispersion of conductive polymer>
[Production Example 1]
Water comprising 0.5% by mass of poly (3,4-ethylenedioxythiophene) as the cationic polythiophene and 0.8% by mass of polystyrene sulfonic acid (number average molecular weight Mn = 150,000) as the polyanion The dispersion (manufactured by Bayer AG, trade name: Baytron P) was used as it was to obtain an aqueous dispersion of a conductive polymer (solid content concentration: 1.3% by mass).

<Silane compound>
[Production Example 2]
β- (3,4-epoxycyclohexyl) ethyltriethoxysilane (manufactured by Momentive Performance Materials Japan, trade name: Coatosil (registered trademark) 1770) was diluted with isopropanol (IPA) to obtain a solid content. A component having a concentration of 1.0% by mass was designated as B1 component.

[Production Example 3]
γ-Glycidoxypropyltriethoxysilane was diluted with isopropanol (IPA) to give a solid content concentration of 1.0% by mass as B2 component.

<Water-soluble polyester>
[Production Example 4]
Product name: Plus Coat Z-658 (Tg = 45 ° C. aqueous solution of water-soluble polyester resin, solid content concentration 25% by mass) was used as it was as C1 component.
Pluscoat Z-658 is a water-soluble polyester resin in which 3 mol% of 5-Na sulfoisophthalic acid is copolymerized in 100 mol% of an acid component.

[Production Example 5]
Product name: Plus Coat RZ-570 (Tg = 60 ° C. aqueous solution of water-soluble polyester resin, solid content concentration 25% by mass) was used as it was as C2 component.
Pluscoat RZ-570 is composed of terephthalic acid (80 mol%), isophthalic acid (14 mol%) and 5-Na sulfoisophthalic acid (6 mol%). The glycol component is ethylene glycol (74 mol%). %), Diethylene glycol (8 mol%), and hexamethylene glycol (18 mol%). The weight average molecular weight Mw of Pluscoat RZ-570 is 23,000.

[Production Example 6]
Made by Takamatsu Yushi Co., Ltd., trade name: Pesresin A-610 (aqueous dispersion of acrylic modified polyester resin with Tg = 47 ° C., solid content concentration 25 mass%) was used as it was as C3 component.
The number average molecular weight Mn of pesresin A-610 is 3,000.

[Example 1]
97 parts by mass of the aqueous dispersion of conductive polymer obtained in Production Example 1 and 3 parts by mass of diethylene glycol were mixed and stirred for 1 hour. Then, 3.2 parts by mass of the B1 component obtained in Production Example 2 was added, and the mixture was further stirred for 15 minutes, and then 0.5 parts by mass of the C1 component obtained in Production Example 4 was added. The mixture was stirred for a time to obtain a coating agent (solid content concentration: 4.3% by mass).
The obtained coating agent is applied onto a PET film (trade name: O3PF8W-100, manufactured by Teijin DuPont Films, Ltd.), which is a base film, using a Mayer bar, followed by drying at 150 ° C. for 1 minute. As a result, a conductive film in which a transparent conductive coating layer having a thickness of 80 nm was laminated was obtained. In addition, content of the silane compound in a transparent conductive coating film layer was 2.5 mass parts with respect to 100 mass parts of conductive polymers. Moreover, content of water-soluble polyester in a transparent conductive coating film layer was 10 mass parts with respect to 100 mass parts of conductive polymers. Table 1 shows the properties of the obtained conductive film.

[Example 2]
Example 1 except that the addition amount of the C1 component is 1.5 parts by mass (the content of the water-soluble polyester in the transparent conductive coating layer is 30 parts by mass with respect to 100 parts by mass of the conductive polymer). In the same manner, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in Example 2 was 4.5 mass%.

[Example 3]
The same as in Example 1 except that the addition amount of the C1 component is 3 parts by mass (the content of the water-soluble polyester in the transparent conductive coating layer is 60 parts by mass with respect to 100 parts by mass of the conductive polymer). Thus, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in Example 3 was 4.8 mass%.

[Example 4]
Example 1 except that the addition amount of the C1 component is 3.5 parts by mass (the content of the water-soluble polyester in the transparent conductive coating layer is 70 parts by mass with respect to 100 parts by mass of the conductive polymer). In the same manner, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in Example 4 was 4.8 mass%.

[Example 5]
Example except that the addition amount of the B1 component is 1.3 parts by mass (the content of the silane compound in the transparent conductive coating layer is 1.0 part by mass with respect to 100 parts by mass of the conductive polymer) In the same manner as in Example 2, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in Example 5 was 4.5 mass%.

[Example 6]
Example except that the addition amount of the B1 component is 6.3 parts by mass (the content of the silane compound in the transparent conductive coating layer is 5.0 parts by mass with respect to 100 parts by mass of the conductive polymer). In the same manner as in Example 2, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in Example 5 was 4.4 mass%.

[Example 7]
A conductive film was obtained in the same manner as in Example 2 except that the C2 component obtained in Production Example 5 was used instead of the C1 component. Table 1 shows the properties of the obtained conductive film.

  The conductive films obtained in Examples 1 to 7 were excellent in transparency and conductivity. In particular, the adhesiveness between the base film and the transparent conductive coating layer was excellent, the surface resistance value change rate before and after the wet heat treatment was low, and the heat and moisture resistance was excellent. Furthermore, the touch panel using them was excellent in durability, and had a low rate of change in contact resistance before and after wet heat treatment, and was excellent in wet heat resistance.

[Comparative Example 1]
A conductive film was obtained in the same manner as in Example 1 except that the C1 component was not added. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in the comparative example 1 was 4.2 mass%.
The conductive film obtained in Comparative Example 1 was inferior in coating film adhesion and coating film strength because the transparent conductive coating film layer did not contain water-soluble polyester. Therefore, the touch panel using it was inferior in durability.

[Comparative Example 2]
Example 1 except that the addition amount of the C1 component is 0.3 parts by mass (the content of the water-soluble polyester in the transparent conductive coating layer is 6 parts by mass with respect to 100 parts by mass of the conductive polymer). In the same manner, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in the comparative example 2 was 4.2 mass%.
The conductive film obtained in Comparative Example 2 was inferior in coating film adhesion and coating film strength because of the low content of water-soluble polyester in the transparent conductive coating film layer. Therefore, the touch panel using it was inferior in durability.

[Comparative Example 3]
Example 1 except that the amount of the C1 component added is 4 parts by mass (the content of the water-soluble polyester in the transparent conductive coating layer is 80 parts by mass with respect to 100 parts by mass of the conductive polymer). Thus, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in the comparative example 3 was 4.9 mass%.
The conductive film obtained in Comparative Example 3 was inferior in heat-and-moisture resistance because the transparent conductive coating layer contained too much water-soluble polyester. Therefore, the touch panel using it was also inferior in heat-and-moisture resistance.

[Comparative Example 4]
A conductive film was obtained in the same manner as in Example 2 except that the component B1 was not added. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in the comparative example 4 was 4.6 mass%.
The conductive film obtained in Comparative Example 4 was inferior in heat and moisture resistance because the transparent conductive coating layer did not contain a silane compound. Therefore, the touch panel using it was also inferior in heat-and-moisture resistance.

[Comparative Example 5]
Example 2 except that the addition amount of the B1 component is 12.6 parts by mass (the content of the water-soluble polyester in the transparent conductive coating layer is 10 parts by mass with respect to 100 parts by mass of the conductive polymer). In the same manner, a conductive film was obtained. Table 1 shows the properties of the obtained conductive film.
In addition, the solid content density | concentration of the coating material in the comparative example 5 was 4.2 mass%.
Since the conductive film obtained in Comparative Example 5 contained too much silane compound in the transparent conductive coating layer, it was poor in heat and humidity resistance. Therefore, the touch panel using it was also inferior in heat-and-moisture resistance.

[Comparative Example 6]
A conductive film was obtained in the same manner as in Example 2 except that the B2 component obtained in Production Example 3 was used instead of the B1 component. Table 1 shows the properties of the obtained conductive film.
The conductive film obtained in Comparative Example 6 was inferior in moisture and heat resistance because the silane compound in the transparent conductive coating layer did not have an epoxycyclohydrocarbon group. Therefore, the touch panel using it was also inferior in heat-and-moisture resistance.

[Comparative Example 7]
A conductive film was obtained in the same manner as in Example 2 except that the C3 component obtained in Production Example 6 was used instead of the C1 component. Table 1 shows the properties of the obtained conductive film.
Comparative Example 7 is an experimental example using a water-dispersible acrylic modified polyester instead of the water-soluble polyester. In Comparative Example 7, the coating film adhesion and the coating film strength could be improved by adding the water-dispersible acrylic-modified polyester, but the surface resistance value change rate and the contact resistance value change rate were large. The moisture and heat resistance was poor. Therefore, the touch panel using it was also inferior in heat-and-moisture resistance.

It is a figure which shows the measuring method of the contact resistance value using a simple touch panel.

Explanation of symbols

1 Air gap (size 9cm x 6cm)
2 Spacer (PET film with a thickness of 100 μm, size 10 cm x 7 cm)
3a Upper electrode (size 10cm x 7cm)
3b Lower electrode (size 10cm x 7cm)
4 Terminal 5, 6 Conductor 7 Tester positive test lead 8 Tester negative test lead

Claims (6)

On at least one side of the base film,
(I) a conductive polymer (A) comprising a cationic polythiophene containing a repeating unit represented by the following formula (I) as a main component and a polyanion;
(Ii) silane compound (B) having an epoxycyclohydrocarbon group of 0.5 to 9 parts by mass with respect to 100 parts by mass of the conductive polymer, and (iii) 100 parts by mass of the conductive polymer 10 to 70 parts by mass of a water-soluble polyester (C) having a hydroxyl group or a carboxyl group at least at the terminal or side chain
A conductive film in which a transparent conductive coating layer containing as a constituent component is laminated.
(In formula (I), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or may be optionally substituted together. Represents an alkylene group having 1 to 12 carbon atoms.)   2. The conductive film according to claim 1, wherein the rate of change in surface resistance before and after treatment at a temperature of 60 ° C. and a relative humidity of 90% for 240 hours is 120% or less.   The conductive film according to claim 1 or 2, wherein a contact resistance value change rate before and after being treated at a temperature of 60 ° C and a relative humidity of 90% for 240 hours is 150% or less. 10 mm ² gauze impregnated with ion-exchanged water as a rubbing part on the surface of the conductive film on the transparent conductive coating layer side of the conductive film (Suzuran Co., Ltd., cotton yarn 40 count in 1 cm square Claims are made by striking 5 strokes under the conditions of a load of 700 g and a speed of 1 reciprocation / 2 seconds, and the transparent conductive coating layer in the rubbed part remains 60% or more in area. The electroconductive film of any one of 1-3. ^5. The conductive film according to claim 1, wherein the total light transmittance is 80% or more, and the surface resistance value is 10Ω / □ or more and 1 × 10 ⁵ Ω / □ or less.   The resistance film type touch panel in which a pair of electrodes having a conductive layer is arranged so that the conductive layers face each other with a spacer interposed therebetween, and at least one of the electrodes is described in any one of claims 1 to 5. A touch panel using a conductive film.