TWI486413B - Conductive paste, conductive film, touch panel and method for producing conductive thin film - Google Patents

Description

Conductive paste, conductive film, touch panel, and method for producing conductive film

The present invention relates to a conductive paste and a use thereof, and more particularly to a conductive paste containing a polyurethane resin as a binder resin, using a conductive film composed of the conductive paste and In the manufacturing method, the conductive film is a conductive laminated body laminated on the transparent conductive layer, and a touch panel using the conductive laminated body.

A transparent touch panel that operates by touching a screen with a finger or a special pen has been used for information on ATMs, car satellite positioning systems, game machines, station vending machines, photocopiers, museum commentary terminals, and convenience stores. A wide range of uses such as terminals.

The transparent touch panel is configured by overlapping two transparent conductive films to form a switching pattern. In general, the transparent conductive film of such a transparent touch panel is adhered to an indium tin oxide film (hereinafter, also referred to simply as an ITO film) which is a transparent electrode material by a vapor deposition method or a sputtering method. The ITO film is etched by a base material such as a polyester film or glass to form a pattern.

There are various ways for the touch panel, and the resistive film method and the electrostatic capacity method are representative.

The resistive film method is characterized in that it can be manufactured simply and at low cost by a simple structure in which the sensed pressure is specifically contacted, and it is easy to perform detailed position detection, and can also correspond to character input obtained by a pen. On the other hand, the disadvantage is that, due to the structure in which the conductive film is attached to the liquid crystal, the transmittance of the screen is lowered, and it is difficult to achieve a clear picture.

The electrostatic capacitance method is characterized in that multi-point sensing can be performed by a specific position by sensing a discharge phenomenon or the like caused by touching a panel with a finger or a dedicated pen.

When the touch panel is to be input by a pen or a fingertip or the like, the transparent conductive film on the fixed electrode side and the transparent conductive film on the movable electrode (thin film electrode) side are in contact with or close to each other. In recent years, with the variety of pen input patterns observed in game machines and the like, and the load at the time of input, especially in the transparent conductive film, cracks, peeling, and the like are caused by the load due to the pen input. Destruction becomes a problem. Therefore, it is necessary to improve the durability of the pen friction, and in recent years, attempts have been made to improve the strength of the transparent conductive film.

In an attempt to increase the strength of the transparent conductive film, for example, it is considered that the oxide constituting the film is crystallized to be effective. In order to crystallize the transparent conductive film, the obtained laminated film is heated to a temperature higher than the crystallization temperature of the transparent conductive film after the amorphous conductive film is grown on the plastic film substrate. For example, Patent Document 1).

In addition, as shown in Patent Document 2, an indium oxide powder having a predetermined specific surface area value and an average particle diameter, and a tin oxide powder are mixed and pulverized, and a molded body is obtained by press molding in addition to a predetermined tin oxide content. In order to obtain a crystalline ITO film, etc., each company aims to improve the crystallization rate in order to improve durability.

On the other hand, as described above, as the oxide constituting the transparent conductive film is crystallized, it is difficult to ensure the adhesion of the conductive coating film formed on the transparent conductive film. In general, the conductive coating film forming the connection electrode is formed by screen printing using a conductive paste containing a conductive powder such as silver, and the oxide constituting the transparent conductive film is crystalline. The order of maintaining the surface structure of the transparent conductive film by crystallization tends to be low in surface activity and the fixing effect due to unevenness tends to be lowered. Further, since the order of the structure is maintained, the effect of the solvent existing in the conductive paste on the undercoat layer tends to be weaker than that of the amorphous transparent conductive film. For these reasons, it is difficult to ensure the adhesion after drying.

Based on the above facts, the adhesion to the crystalline transparent conductive film is particularly good, and a conductive paste which is possible for ensuring low-temperature processing of conductivity is being strongly sought, and the development of such a conductive paste is not sufficient.

Conventional conductive pastes for touch panels are often used in many cases where conductive pastes used for electrode applications such as conventional film switching or pressure sensors are used for touch panels. For example, in the conductive paste shown in Patent Document 3, a polyester resin having a glass transition temperature of 80 ° C or higher is used, and such a polyester resin is used as a touch panel, and the adhesion and the composition are used. The oxide of the transparent conductive film does not have a site capable of interacting, and is not suitable from the viewpoint of adhesion. Similarly, in Patent Document 4, a conductive paste containing a polyester resin or a polyurethane resin as a binder resin is disclosed, and the adhesion to the crystalline transparent conductive film is not necessarily sufficient. In other words, the design concept of the resin or the additive for improving the adhesion to the oxide constituting the transparent conductive film is not introduced, and the adhesion is different depending on the type of the oxide, and is particularly transparent with respect to the crystallinity. The adhesion of the conductive film has to be said to be extremely scarce.

Further, Patent Document 5 discloses an organic resin having a glass transition temperature of 50 ° C or higher, particularly a conductive paste having a polyester resin as a structural component. The polyester resin used in the examples and comparative examples of Patent Document 5 lacks specificity depending on the glass transition temperature, and it is difficult to verify the effect. If it is difficult to crystallize according to the investigation of the present inventors, The adhesion of the conductive film is not necessarily sufficient. Further, similarly to the case of Patent Document 4, the design idea of a resin or an additive for improving the adhesion to the oxide constituting the transparent conductive film is not introduced, and the adhesion is different depending on the type of the oxide. In particular, it has to be said that the adhesion to the crystalline transparent conductive film is extremely lacking.

On the other hand, in the thermosetting conductive paste used in Patent Document 6, in addition to the portion where the resin and the transparent conductive film do not interact with each other, the film is made of a thermosetting type at 150 ° C or higher. If temperature is necessary, there will be a problem of causing thermal deformation of the underlayer and a decrease in productivity.

On the other hand, in Patent Document 3, the silver paste for a touch panel is attempted to ensure adhesion to ITO by blending a decane coupling agent. However, since the decane coupling agent is low in molecular weight, it affects only conductivity or surface hardness by the effect of the plasticizer, and is not preferable in terms of long-term reliability. Further, since the decane coupling agent is used in the form of a small amount of an additive, there is a concern that the deviation in the coating film is likely to occur and the coating film may flow out for a long period of time.

Patent Document 1: JP-A-2005-141981

Patent Document 2: JP-A-2004-323877

Patent Document 3: JP-A-2003-203523

Patent Document 4: JP-A-2003-223812

Patent Document 5: JP-A-2006-059720

Patent Document 6: JP-A-1-159906

An object of the present invention is to provide a conductive paste for forming a conductive film, which is excellent in adhesion to a substrate having a transparent conductive layer or the like, and can provide high reliability and high conductivity.

In order to solve such a problem, as a result of the drill collar, the following findings are obtained: in the conductive paste, the binder resin is contained in the conductive paste containing a polyaminourethane having a specific number average molecular weight, an acid value, and a glass transition temperature. The ester resin is useful as a conductive paste for forming a conductive film. The present invention has been accomplished based on such insights.

Item 1: A conductive paste comprising:

(A) component, an adhesive resin composed of a polyurethane resin having an acid value of 50 to 500 eq/ton and a glass transition temperature of 60 to 150 ° C;

(B) component consisting of metal powder; and

The component (C) is composed of an organic solvent.

Item 2: The conductive paste of Item 1, wherein the component (A) is a polyurethane having a structure obtained by addition polymerization of (A1), (A2) and (A3) Adhesive resin composed of resin:

(A1) an amorphous polyalcohol having a number average molecular weight of 1,000 to 10,000 and a glass transition temperature of 30 to 80 ° C,

(A2) a compound having a number average molecular weight of less than 1,000 and having two or more functional groups reactive with isocyanate in one molecule, and

(A3) Polyisocyanate.

Item 3: The conductive paste of Item 1 or 2, wherein the component (A) is obtained by having a structure obtained by addition polymerization of (A1), (A2), (A3) and (A4) Adhesive resin composed of polyurethane resin:

(A1) an amorphous polyalcohol having a number average molecular weight of 1,000 to 10,000 and a glass transition temperature of 30 to 80 ° C,

(A2) a compound having a number average molecular weight of less than 1,000 and having two or more functional groups capable of reacting with an isocyanate in one molecule,

(A3) polyisocyanate, and

(A4) An amorphous polyalcohol having a number average molecular weight of 1,000 to 10,000 and a glass transition temperature of less than 30 °C.

Item 4: The conductive paste according to Item 2 or 3, wherein the amorphous polyalcohol (A1) is an amorphous polyester polyalcohol, wherein the amorphous polyester polyol has a total of a polycarboxylic acid and all the polyalcohol components When it is 100 mol%, the aromatic dicarboxylic acid is 60 mol% or more in all the polycarboxylic acid components, and the diol having a carbon number of 4 or less in the main chain is 60 mol in all the polyhydric alcohol components. %the above.

The conductive paste according to any one of items 2 to 4, wherein the functional group reactive with the isocyanate in the compound (A2) is a hydroxyl group or an amine group.

The conductive paste of any one of items 2 to 5, wherein the compound (A2) further contains a carboxyl group.

The conductive paste according to any one of items 1 to 6, wherein the component (B) further contains a conductive powder other than the metal powder.

Item 8: The conductive paste according to any one of Items 1 to 7, wherein the content of the component (B) is from 400 to 1,900 parts by mass relative to 100 parts by mass of the binder resin (A).

Item 9: The conductive paste according to any one of Items 1 to 8, wherein the content of the component (C) is from 150 to 500 parts by mass relative to 100 parts by mass of the binder resin (A).

Item 10: A conductive film comprising the conductive paste disclosed in any one of Items 1 to 9.

Item 11: A conductive laminate in which a conductive film disclosed in Item 10 is laminated on a transparent conductive layer.

Item 12: The conductive laminate according to Item 11, wherein the transparent conductive layer is an ITO film comprising indium tin oxide as a main component.

Item 13: A touch panel using the conductive laminate disclosed in Item 11 or 12.

Item 14: A method for producing a conductive film, comprising the step of coating or printing a conductive paste according to any one of Items 1 to 9 on a substrate; and heating at 80 to 150 °C.

In the conductive paste of the present invention, since the binder resin contained in the present invention has a high glass transition temperature, it is possible to maintain a good film even in a high-temperature environment when forming a film, and has high reliability. Further, in the binder resin, when a film is formed on a substrate due to a specific acid value, peeling due to adhering substances such as adsorbed water existing on the substrate is small, and the resin can be remarkably The adhesion of other materials is improved.

Therefore, it is suitable for the use of a touch panel or the like which is required for particularly good adhesion, high reliability, and conductivity.

Hereinafter, each component of the conductive paste of the present invention will be described in detail.

(A) component

The binder resin (A) of the polyurethane resin is required to have a urethane bond.

By having a urethane bond, in the hardening of the conductive paste or the post-printing hardening, the conductive powder such as the metal powder inside the coating film is mutually made according to the high cohesive force due to the intermolecular hydrogen bond. The distance is close and high conductivity can be found. Further, in the case of low-temperature drying, for example, in the case of a residual solvent, high conductivity and high adhesion to the substrate can be found depending on the high cohesive force of the binder resin. The urethane bond system is formed at least according to the reaction of the amorphous polyalcohol and the polyisocyanate. Further, in a preferred embodiment, the coefficient average molecular weight is less than 1,000, and two or more molecules are contained in one molecule to be reacted with the isocyanate. A compound formed by the reaction of a functional group with a reaction with a polyisocyanate.

The number average molecular weight of the binder resin is 10,000 or more, preferably 20,000 or more, from the viewpoint of durability of the binder resin. When the number average molecular weight is less than 10,000, in addition to the problem of long-term durability, the paste viscosity will be lowered and the printability will be lowered. Further, the number average molecular weight of the binder resin is preferably 100,000 or less from the viewpoint of paste viscosity (screen printing suitability) and solubility.

The binder resin-based glass has a glass transition temperature of 60 ° C or higher, preferably 70 ° C or higher. When the glass transition temperature is lower than 60 ° C, when the hardener is not blended, the resin will be softened at a high temperature, and the reliability as a paste will be lowered. Further, the surface hardness is lowered, and the adhesion is lowered during the manufacturing process and/or the use of the resin or the blend to the contact side. When the adhesion, solubility, paste viscosity, and printability are considered, the glass transition temperature of the binder resin is preferably 150 ° C or lower, more preferably 120 ° C or lower, and still more preferably 100 ° C or lower. The glass transition temperature of the binder resin is selected from amorphous polyols A1, A4, a compound A2 having a functional group reactive with isocyanate in one molecule, a composition ratio of polyisocyanate A3, and A1, A2, The chemical structure of A3 and A4 can be adjusted. In order to find the glass transition temperature within the scope of the patent application of the present invention, the glass transition temperature of A1 is preferably 40 ° C or higher, and the polyisocyanate is preferably at least one having an alicyclic skeleton and/or an aromatic skeleton, and the composition thereof is compared. Preferably, the mass ratio A1>A3>A2, and preferably, the mass ratio A1>A4.

The binder resin has a specific range of acid value. By imparting an acid value, the adhesion is remarkably improved in accordance with the chemical interaction with the adsorbed water present in the transparent conductive layer.

The acid value of the binder resin is from 50 to 500 eq/ton, preferably from 100 to 350 eq/ton. When the acid value is lower than 50 eq/ton, the adhesion improving effect of the obtained conductive film and the transparent conductive film tends to be small. On the other hand, when the acid value exceeds 500 eq/ton, in addition to high water absorption, it has a possibility of promoting hydrolysis of the binder resin according to the action of the catalyst, and has a property of lowering the reliability of the electrode when the conductive film is formed. The tendency.

The method of introducing the acid value into the binder resin may be exemplified by the following method: copolymerization of the dimethylol group in the chain extension step of the polyol and the polyisocyanate in the step of the polyurethane resin of the binder resin a compound containing two or more functional groups in a molecule containing a carboxyl group such as an acid or dimethylolpropionic acid; or a polyvalent carboxylic acid anhydride such as trimellitic anhydride, benzophenone tetracarboxylic acid or trishydroxymethyl anhydride; The acid value is introduced into the molecule or at the end of the molecule. The method of introducing an acid value of the present invention may use any of the above methods.

The binder resin (A) is preferably a polyester urethane resin having a molecular weight of at least (A1) of 1,000 to 10,000, preferably 1,500 to 7,000, and a glass transition temperature of 30 to 80 ° C, preferably 45 to An amorphous polyalcohol at 70 ° C; (A2) a compound having a number average molecular weight of less than 1,000, preferably 60 to 400, having two or more functional groups reactive with isocyanate in one molecule; and (A3) It is produced by addition polymerization of polyisocyanate. Further, the binder resin (A) is also preferably a polyester urethane resin, and at least (A1) has a molecular weight of 1,000 to 10,000, preferably 1,500 to 7,000, and a glass transition temperature of 30 to 80 ° C, preferably An amorphous polyalcohol of 45 to 70 ° C; (A2) a compound having a number average molecular weight of less than 1,000, preferably 60 to 400, having two or more functional groups reactive with isocyanate in one molecule; (A3) Isocyanate; and (A4) preferred polyester urethane resin produced by addition polymerization of amorphous polyol having a molecular weight of 1,000 to 10,000, preferably 1,500 to 7,000, and a glass transition temperature of less than 30 ° C . The amorphous polyol may, for example, be a polyether polyol, a polyester polyol or the like, and is preferably a polyester polyol based on the degree of freedom in molecular design. The polyester polyol is preferably obtained by condensation of a dicarboxylic acid with a polyalcohol. Further, the dicarboxylic acid may also be a dicarboxylic acid ester esterified with an alcohol having 1 to 12 carbon atoms.

Examples of the dicarboxylic acid used in the production of the polyester polyol include aromatic diacids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid; succinic acid; An aliphatic diacid such as glutaric acid, adipic acid, sebacic acid, dodecanedioic acid or sebacic acid; dibasic acid having a carbon number of 12 to 28 such as a dimer acid; Cyclohexanedioic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexa An alicyclic group of hydrogen phthalic anhydride, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalic acid, tricyclic sebacic acid, etc. Diacid or alicyclic dianhydride; hydroxybenzoic acid, hydroxycarboxylic acid such as lactic acid, and the like. Further, in the range which does not impair the effects of the invention, it may be copolymerized with a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic anhydride or an unsaturated dicarboxylic acid such as fumaric acid; Copolymerization of a sulfonic acid metal base-containing dicarboxylic acid such as a sulfoisophthalate salt.

The amorphous polyol (A1) is preferably a polyester polyol, and constitutes an aromatic group among all the acid components of the polyester polyol based on the viewpoints of durability such as strength, heat resistance, moisture resistance and thermal shock resistance. The dicarboxylic acid is preferably copolymerized at 60 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and particularly preferably 98 mol% or more. The entire acid component is a preferred embodiment composed of an aromatic dicarboxylic acid. When the amount of the aromatic dicarboxylic acid component is less than 60% by mole, the glass transition temperature of the polyurethane resin (A) of the present invention is lower than 60 ° C, and the heat and humidity resistance and durability are lowered. . On the other hand, the amorphous polyol (A4) is preferably a polyester polyol, and among the entire acid components constituting the polyester polyol, the aromatic dicarboxylic acid is preferably 30 mol% or more, preferably 50. Mole% or more, further preferably 70 mol% or more.

Examples of the diol used in the production of the polyester polyol include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, and neopentane. Glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2, An aliphatic diol such as 2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,9-nonanediol or 1,10-decanediol; An alicyclic diol such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol or a dimer diol. Further, a polyhydric alcohol such as trimethylolethane, trimethylolpropane, glycerin, neopentyl glycol or polyglycerin may be used in combination without damaging the invention.

The amorphous polyalcohol (A1) is preferably a polyester polyol, and is composed of all the polyol components of the polyester polyol based on the viewpoints of durability such as strength, heat resistance, moisture resistance and thermal shock resistance. The diol having a carbon number of 4 or less in the chain is preferably 60 mol% or more, more preferably 80 mol% or more, still more preferably 95 mol% or more. In all the polyol components, if the diol having a carbon number of 4 or less in the main chain becomes less than 60 mol%, it is feared that the glass transition temperature of the polyurethane resin A of the present invention is lower than 60 ° C. Worried about heat and humidity resistance, durability will be reduced. On the other hand, the amorphous polyol (A4) is preferably a polyester polyol which constitutes all the polyol components of the polyester polyol, and the ethylene glycol having a carbon number of 4 or less in the main chain is preferably 80 moles. % or less, more preferably 70% by mole or less, still more preferably 60% by mole or less.

The binder resin (A) used in the present invention can be a compound (A2) having at least the amorphous polyol (A1) and a functional group having a number average molecular weight of less than 1,000 and having two or more reactable isocyanates in one molecule. And the addition polymerization reaction of the polyisocyanate (A3) shown below. Further, the binder resin (A) is at least the amorphous polyalcohols (A1) and (A4) and has a number average molecular weight of less than 1,000, and can be a compound having two or more functional groups reactive with isocyanate in one molecule. (A2) is produced by addition polymerization reaction of polyisocyanate (A3) shown below. The functional group obtainable by the reaction with the isocyanate in the compound (A2) is preferably a hydroxyl group and an amine group, and the compound (A2) may have either or both of them. Specific (A2) component, as described above, as a carboxyl group-containing compound of dimethylol butyric acid or dimethylolpropionic acid used as an acid value introduction method, 1,2-propanediol, 1 , 2-butanediol, 1,3-butanediol, 2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2-dimethyl-3-hydroxypropyl-2', 2' - dimethyl-3-hydroxypropionate, 2-n-butyl-2-ethyl-1,3-propanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5 - hexanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol, 3-phenyl-1,5-pentanediol, 2,5-di a compound having two hydroxyl groups in one molecule such as methyl-3-sulfo sodium-2,5-hexanediol or dimer diol (PRIPOL-2033 (manufactured by Unichema International)); trishydroxymethyl B a polyhydric alcohol such as an alkane, a trimethylolpropane, a glycerin, a neopentyl glycol or a polyglycerol; an amino alcohol having one or more hydroxyl groups and an amine group in one molecule such as monoethanolamine, diethanolamine or triethanolamine; Diamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-octanediamine, 1,10-decanediamine , 1,11-undecanediamine, 1,12-dodecanediamine, etc., aliphatic diamine or m-xylene diamine, 4,4-diaminodiphenylmethane, 3,4'- An aromatic diamine having two amine groups in one molecule such as diaminodiphenyl ether or 4,4'-diaminodiphenyl ether. The above-mentioned number average molecular weight is less than 1,000, and a compound having two or more functional groups reactive with isocyanate in one molecule may be used singly or in combination of several kinds without any problem.

Examples of the polyisocyanate (A3) constituting the binder resin (A) include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and Benzene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 2,6-naphthalene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl Isocyanate, 4,4'-diphenyl diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, m-xylene diisocyanate, isophorone diisocyanate, dibutyl diisocyanate, Dihexamethylene diisocyanate, toluene diisocyanate, etc.

The polyisocyanate (A3) and the amorphous polyalcohol (A1) have a number average molecular weight of less than 1,000, and can be reacted by a compound (A2) having two or more functional groups capable of reacting with an isocyanate in one molecule. The urethane bond is introduced into the binder resin (A). Further, the polyisocyanate (A3) and the amorphous polyalcohol (A1), (A4) and a compound having a number average molecular weight of less than 1,000 and having two or more functional groups reactive with isocyanate in one molecule (A2) The reaction can introduce a urethane bond into the binder resin (A).

The binder resin (A) can be polymerized in a solvent, and the solvent preferably has a boiling point of 80 ° C or higher. When the solvent having a boiling point of 80 ° C or higher is low in volatility, the metal powder and the conductive powder or other blend other than the desired metal powder are blended, and then dispersed by a three-roller or the like, It is necessary to carry out solvent replacement, and it is possible to perform work efficiently, and it also has an advantage from a viewpoint of cost. On the other hand, after the binder resin (A) is polymerized in a solventless manner, it is not problematic even if it is dissolved in a solvent having a boiling point of 80 ° C or higher.

The solvent having a boiling point of 80 ° C or higher can use various solvents such as toluene, xylene, tetramethylbenzene, Solvesso 100, Solvesso 150, Solvesso 200, tetrahydronaphthalene, etc.; aliphatic hydrocarbons such as Decalin An alcohol system such as terpineol; a ketone system such as methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone; ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; , diethylene glycol monoethyl ether, dipropylene glycol diethyl ether, two An ether system such as an alkane, a diethyl ether or a tetrahydrofuran; a cellulose system such as cellulose acetate, ethyl cellulose or butyl cellulose; a ketone alcohol such as carbitol or butyl carbitol; Solvent. In the polymerization, there is no problem even if two or more kinds of the solvent are mixed.

In the case of blending the respective monomers in the production of the binder resin (A), in addition to the solvent, as long as the effect of volatilization at the time of three rolls can be suppressed, a solvent having a boiling point lower than 80 ° C is added without any problem. . In addition, a solvent having a boiling point of less than 80 ° C is added before use, and no limitation is imposed.

In the binder resin, a hardener which can react with a polyurethane resin having a urethane bond can be blended to the extent that the effects of the present invention are not impaired. By blending the curing agent, there is a possibility that the curing temperature is increased, and improvement in reliability due to improvement in physical properties of the coating film can be expected. The curing agent which can be obtained by the reaction with the binder resin of the present invention is not limited, but is preferably an isocyanate compound based on adhesion, bending resistance, curability, and the like. Further, based on the storage stability, it is preferred to use a blocked isocyanate group as the isocyanate compound. Examples of the curing agent other than the isocyanate compound include amine-based resins such as methylated melamine, butylated melamine, benzoguanamine, and urea resins, acid anhydrides, imidazoles, epoxy resins, and phenol resins. Know the compound.

Examples of the isocyanate compound include an aromatic or aliphatic diisocyanate, a trivalent or higher polyisocyanate, and the like, and any of a low molecular compound and a polymer compound. Examples thereof include a butyl diisocyanate and a hexamethylene diisocyanate. An aromatic diisocyanate such as aliphatic diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate or xylene diisocyanate; hydrogenated diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, dimer acid diisocyanate, etc. An alicyclic diisocyanate such as isophorone diisocyanate or a trimeric amount of such an isocyanate compound, and an excess amount of such an isocyanate compound, for example, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, A low molecular weight active hydrogen compound such as sorbitol, ethylenediamine, monoethanolamine, diethanolamine or triethanolamine or a polymer active hydrogen compound of various polyester polyols, polyether polyols, or polyamines A compound containing a terminal isocyanate group.

Examples of the isocyanate group blocker include phenol, thiophenol, methyl thiophenol, ethyl thiophenol, cresol, xylenol, resorcin, nitrophenol, chlorophenol, and the like. Phenols; anthraquinones such as acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime; alcohols such as methanol, ethanol, and propanol; chlorohydrin, 1,3-dichloro-2-propanol, etc. a halogen-substituted alcohol; a tertiary alcohol such as tertiary butanol or tertiary pentoxide; a lactone of ε-caprolactone, δ-valerolactone, γ-butyrolactone, β-propiolactone or the like; Other examples include active methylene compounds such as aromatic amines, quinone imidizations, acetamidineacetone, acetamidine acetate, and ethyl malonate; thiols, imines, and imidazoles. Urea, diaryl compounds, hydrogen sulfite base, and the like. Among them, based on the curability, hydrazines, imidazoles, and amines are particularly desirable.

Among these hardeners, the selected conventional catalyst or accelerator can be used in combination according to the type thereof.

The blending amount of the hardener is not particularly limited as long as it is blended to the extent that the effect of the present invention is not impaired, and is preferably 0.5 to 50 parts by mass, more preferably 100 parts by mass of the binder resin. It is 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass.

In order to form a conductive film, the conductive paste contains a binder resin (A), and even if it is dried at a low temperature (for example, 135 ° C or lower), it has excellent adhesion to the laminated transparent electrode layer. High conductivity was found.

In addition to the binder resin (A), the conductive paste of the present invention may be used in combination with a urethane resin, a polyester resin, an epoxy resin or a phenol resin other than the specific polyurethane resin. , acrylic resin, styrene-acrylic resin, styrene-butadiene copolymer, polystyrene, polyamide resin, polycarbonate resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, etc. There are no restrictions. However, it is preferable to contain 30 weight% or less with respect to the binder resin (A) to the extent that the characteristics of the binder resin (A) are not impaired. When the resin is used, the type thereof is not limited, and an amine other than the polyester resin or the binder resin (A) is preferred from the viewpoints of adhesion to the substrate, bending resistance, solvent solubility, and compatibility. Formate resin.

(B) component

The metal powder (B) used in the present invention may, for example, be a noble metal powder such as silver powder, gold powder, platinum powder or palladium powder; copper powder, nickel powder, aluminum powder, brass powder or the like; plating or alloying of a noble metal such as silver. After that, metal powder and so on. These metal powders may be used singly or in combination. Among these, it is preferably a single silver powder or a metal powder mainly composed of silver powder.

The shape of the metal powder is flaky (scaly), spherical, or dendritic (pine), and the spherical primary particles disclosed in Japanese Laid-Open Patent Publication No. Hei 9-306240 are agglomerated into a third dimension. Among these shapes, in view of conductivity, it is particularly preferable that the flaky silver powder and the spherical primary particles are silver powder in a shape of agglomerated into a three-dimensional shape.

Further, in addition to the metal powder, a conductive powder other than the metal powder may be further contained. The content of the conductive powder other than the metal powder is preferably 11 parts by mass or less, and more preferably 9 parts by mass or less, based on 100 parts by mass of the metal powder. The lower limit of the content of the conductive powder other than the metal powder is not particularly limited, and is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more based on 100 parts by mass of the metal powder. A conductive powder other than the metal powder may be added with a conventional inorganic substance. For example, a carbon-based filler such as carbon black or graphite powder; cerium carbide, boron carbide, titanium carbide, zirconium carbide, cerium carbide, vanadium carbide, and carbonization may be used. Various kinds of carbides such as bismuth, tantalum carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, diamond carbon decylamine; various nitrides such as boron nitride, titanium nitride, zirconium nitride, etc.; Various borides; various oxides of titanium oxide (titanium), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, cerium oxide, colloidal cerium oxide, etc.; calcium titanate, magnesium titanate, barium titanate Such as titanic acid compounds; sulfides such as molybdenum disulfide; various fluorides such as magnesium fluoride and carbon fluoride; various metals such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate Soap; other, talc, bentonite, calcium carbonate, kaolin, fiberglass, mica, etc. By adding the inorganic substance as described above, it is possible to improve heat resistance or durability.

Further, carbon black and graphite powder are preferred from the viewpoints of environmental characteristics such as conductivity and moisture resistance and cost. The content of the carbon black and/or graphite powder containing carbon black or graphite powder is preferably 25 parts by mass or less, more preferably 11 parts by mass or less, based on 100 parts by mass of the metal powder.

Further, a shake imparting agent, an antifoaming agent, a flame retardant, an adhesion-imparting agent, an anti-hydrolysis agent, a flat agent, a plasticizer, an antioxidant, an ultraviolet absorber, a flame retardant, a pigment, and a dye can be used. Further, as the resin decomposition inhibitor, carbodiimide, epoxide or the like can be suitably used. These additives can be used singly or in combination.

The content of the component (B) is preferably 400 parts by mass or more, and more preferably 560 parts by mass, based on 100 parts by mass of the binder resin (A), from the viewpoint that the conductivity of the formed conductive film is good. More preferably, it is 700 mass parts or more. In addition, the content of the component (B) is preferably 1,900 parts by mass or less, more preferably 1,230, based on 100 parts by mass of the binder resin (A), from the viewpoint of the adhesion to the transparent conductive layer being good. More preferably, it is 750 parts by mass or less.

(C) component

The organic solvent of the component (C) is preferably such that the binder resin of the component (A) is soluble and the conductive powder of the component (B) can be well dispersed. Specific examples include ethylene glycol acetate (ECA), butanediol acetate (BCA), cyclohexanone, methyl ethyl ketone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, and Exxon chemistry. Solvesso 100, 150, 200, propylene glycol monomethyl ether acetate, terpineol, etc. Among these solvents, ethylene glycol acetate is preferred because of solubility and screen printing properties. ECA), butanediol acetate (BCA) or a mixed solvent thereof.

In the stencil printing, the content of the component (C) is preferably 150 parts by mass or more based on 100 parts by mass of the binder resin (A), based on the viewpoint of suppressing blurring after printing or plate blocking. The amount is preferably 200 parts by mass or more, and more preferably 240 parts by mass or more. In addition, the content of the component (C) is preferably 500 parts by mass or less based on 100 parts by mass of the binder resin (A), in view of the smear suppression in the screen printing and the uniformity of the film thickness. More preferably, it is 400 mass parts or less, and further more preferably 300 mass parts or less.

The conductive paste of the present invention is suitable for use as a touch panel, and can be used for electromagnetic wave shielding applications, circuit forming applications of electronic components, conductive adhesives for terminals or wires, and the like as a touch panel.

The F value of the conductive paste of the present invention is preferably from 60 to 95%, more preferably from 75 to 95%. The F value indicates the value of the filler mass portion with respect to 100 parts by mass of all the solid matter contained in the paste, and is represented by F value = (filler mass part / solid part by mass) × 100. The mass part of the filler referred to herein refers to the mass part of the electric powder (B), and the mass part of the solid refers to the mass part of the component other than the solvent, and includes all the conductive powder (B), the binder resin, Other hardeners or additives. When the F value is less than 60%, good electrical conductivity is not obtained, and when it exceeds 95%, the adhesion and/or hardness tend to be lowered. The reduction in print quality is also inevitable.

Further, the present invention also relates to the use of a conductive film composed of the conductive paste and a method for producing the same.

The conductive film is obtained by applying or printing a conductive paste on a substrate, and then curing the coated or printed conductive paste by heating. The coating method may be, for example, a coating by a thin coater or a bar coater, or a method such as a spin coating method or a dip coating method. Moreover, the printing method in the case of forming a conductive film by printing is a method of screen printing method, gravure printing, a flexible printing, and lithographic printing.

The heating temperature at the time of curing the conductive paste applied or printed is preferably 80° C. or higher, and more preferably 100° C. or higher, from the viewpoints of good conductivity, adhesion, and surface hardness of the conductive film after drying. Further preferably more than 110 ° C. Further, the heating temperature is preferably 150 ° C or lower, more preferably 135 ° C or lower, and still more preferably 130 ° C or lower from the viewpoint of heat resistance of the transparent conductive layer of the substrate and energy saving in the production step.

The thickness of the conductive film varies depending on the application to be used, and is preferably 5 μm or more, more preferably 7 μm or more, and still more preferably 9 μm or more, from the viewpoint of good conductivity of the conductive film after drying. Further, the thickness of the conductive film is preferably 30 μm or less, more preferably 25 μm or less, and still more preferably 20 μm from the viewpoint of a good screen printing property and a cost advantage due to a decrease in the silver content in the paste. the following.

Further, examples of the substrate to which the conductive paste is applied include polycarbonate, acrylic, polyimide, polyester, etc., and in the case of use for a touch panel, a transparent conductive layer is preferred. A conductive laminated body in which a conductive thin film is laminated on the transparent conductive layer is formed between the substrate and the conductive film. The transparent conductive layer is preferably an ITO film composed of indium tin oxide as a main component, and has excellent adhesion to the conductive film formed by using a conventional crystalline ITO film. The surface shape of the ITO film may be any surface shape such as a flat object or a material having irregularities.

Furthermore, it relates to a touch panel using the conductive laminate. The touch panel can be exemplified by a resistive film method and a capacitive touch panel, and it is possible to apply any of the touch panels.

The method of manufacturing the touch panel is not particularly limited. For example, it is possible to apply or print a conductive paste by forming a circuit that imparts conductivity after hardening a substrate of a transparent conductive layer such as an ITO film. The conductive paste coated or printed is cured by heating to form a conductive laminated body, and the obtained conductive laminated body can be produced by bonding the conductive laminated body to another conductive laminated body.

[Examples]

Hereinafter, the present invention will be further specifically described by showing examples and comparative examples. In addition, the present invention is not limited to the following embodiments, and the "parts" in the examples mean "parts by mass", and the solid concentration means non-volatile after completely evaporating the solvent. Sexual ingredients.

The physical properties of the polyester resin (P) and the polyurethane resin (U) produced in the production examples described later are shown below (1. Number average molecular weight, 2. Glass transition temperature (Tg), 3. Acid value And 4. Determination of resin composition).

In the following, the conductive paste prepared by using the produced polyester resin (P) and polyurethane resin (U) in the production example is shown in 10. Storage stability and formation using a conductive paste. The measurement of the physical properties of the test piece (5. Adhesion, 6. Specific resistance, 7. Pencil hardness, 8. Environmental test, and 9. Anti-caking resistance).

Number average molecular weight

The sample resin was dissolved or diluted in tetrahydrofuran so as to have a resin concentration of about 0.5% by weight, and filtered using a polytetrafluoroethylene filter having a pore diameter of 0.5 μm to prepare a GPC measurement sample. Tetrahydrofuran was used as a mobile phase, and a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation was used, and a differential refractometer (RI meter) was used as a detector. The column temperature was 30 ° C, and the resin was flowed at a flow rate of 1 ml/min. GPC measurement of the sample. The polystyrene-equivalent number average molecular weight of the sample resin was determined by GPC measurement results of monodisperse polystyrene having a known number average molecular weight, and this value was taken as the number average molecular weight of the sample resin in the application of the present invention. However, the pipe string is Shodex KF-802, 804L, and 806L manufactured by Showa Denko Electric Co., Ltd.

2. Glass transition temperature (Tg)

5 mg of the sample resin was placed in an aluminum sample pan and sealed, and a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Co., Ltd. was used, and the measurement was carried out at a temperature increase rate of 20 ° C/min until 200 ° C. The baseline extension line below the glass transition temperature is determined from the junction temperature of the maximum sloped connection in the transition portion.

3. Acid price

0.2 g of the sample resin was dissolved in 20 ml of chloroform. Next, it was determined by titration with 0.01 N potassium hydroxide (ethanol solution). In the indicator, a phenolphthalein solution was used. The unit of the acid value is eq/ton, that is, the equivalent of 1 ton of the sample.

4. Resin composition

The sample resin was dissolved in chloroform-d, and a resin composition ratio was determined by ¹ H-NMR using a 400 MHz-NMR apparatus manufactured by VARIAN.

5. Adhesion

The obtained conductive paste was printed on a PET film or a crystalline ITO film having a thickness of 100 μm by a screen printing method by printing in a pattern of 25 × 200 nm, and dried at 150 ° C for 30 minutes to be hardened. The object was made into a test piece. The dry film thickness is formed by a process of 20 to 30 μm. Using this test piece, evaluation was carried out by a peeling test in accordance with JIS K-5600-5-6:1991 using Sellotape (registered trademark) (manufactured by Nichiban Co., Ltd.). However, the number of cuts in each direction of the lattice pattern was 11 and the cutting interval was set to 1 mm. The 100/100 system showed no peeling and the adhesion was good, and the 0/100 system showed complete peeling, and the adhesion was deteriorated.

6. Specific resistance

The obtained test piece was cut into a width of 25 × 450 mm in the same manner as in 5. The sheet resistance and the film thickness were measured, and the specific resistance was calculated. In addition, the thickness of the cured film of five points was measured using the Gauge Stand ST-022 (manufactured by Ono Corporation), and the thickness of the PET film was set to zero, and the average value was used. The sheet resistance was measured using four MILLOOHMMETER 4338B (manufactured by HEWLETT PACKARD Co., Ltd.), and four test pieces of 25 × 450 mm width were measured, and the average value was used.

7. Pencil hardness

The test piece obtained by the adhesion test was placed on a SUS304 plate having a thickness of 2 mm, and measured in accordance with JIS K 5600-5-4:1999, and judged according to the presence or absence of peeling.

8. Environmental test

5. The adhesion test The test piece prepared on the ITO film was subjected to a heat resistance test at 80 ° C for 300 hours and a heat resistance test at 85 ° C and 85% RH (relative humidity) for 300 hours. After standing at room temperature for 24 hours, the resistance value was measured.

Whether the environmental test is good or not is the evaluation of the adhesion of the conductive coating film and the pencil hardness before and after the implementation of the heat resistance test and the damp heat resistance test.

9. Blocking resistance

The two coating films obtained on the ITO film by the adhesion test method were overlapped so that the coating film surface was joined, and a load of 500 g was applied to the conductive coating film portion, and allowed to stand at 80 ° C for 72 hours. Next, the load was removed, and after standing at normal temperature for 1 hour, the quality was judged by the appearance based on the following criteria.

○: The transfer of both sides of the coating film did not occur, and the original coating state was maintained.

╳: Observing the transfer on both sides, peeling occurred.

10. Storage stability

The conductive paste was placed in a Poly container, and the plug was stored at 40 ° C for 1 month. After storage, the specific resistance, pencil hardness, and adhesion were measured using a test piece prepared in the same manner as in 4.

○: The viscosity did not change significantly, and the initial specific resistance, pencil hardness, and adhesion were maintained.

╳: It was confirmed that the viscosity was greatly increased, and the reduction in specific resistance, pencil hardness, and adhesion was confirmed.

Resin manufacturing example Synthesis of polyester polyol (P) Polyester polyol (P-1)

In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 700 parts of dimethyl terephthalate, 700 parts of dimethyl phthalate, 671 parts of ethylene glycol, and 526 parts of new pentane were fed. The diol, 0.48 parts of tetrabutyl titanate, was transesterified at 180 ° C for 3 hours. Subsequently, the pressure was gradually reduced to 1 mmHg or less, and polymerization was carried out at 240 ° C for 1.5 hours. The composition of the obtained copolymerized polyester (P-1) is terephthalic acid / isophthalic acid / / ethylene glycol / neopentyl glycol = 50 / 50 / / 50 / 50 (mole ratio), quantity The average molecular weight was 2,000, the acid value was 2 eq/ton, and Tg = 58 °C. The results are shown in Table 1.

Polyester polyols (P-2) to (P-5) and (P-7)

In addition to the polyester polyol (P-1), the acid component shown in Table 1 and the diol component were used to replace the monomer in the form of the molar ratio of Table 1, and the polyester polyol (P- 1) Synthesis by the same synthesis method. The composition of the polyester polyols (P-1) to (P-5) and (P-7) and the physical properties of the resin are shown in Table 1.

Synthesis of polyester resin (P-6)

In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 700 parts of dimethyl terephthalate, 700 parts of dimethyl phthalate, 16.9 parts of trimellitic anhydride, and 983 parts of ethylene glycol were fed. 154 parts of 2-methyl-1,3-propanediol was subjected to an esterification reaction under a pressure of two atmospheres under a nitrogen atmosphere at a temperature of from 160 ° C to 230 ° C for 3 hours. After the pressure was released, 0.92 parts of tetrabutyl titanate was fed, and then the system was gradually depressurized, and the pressure was reduced to 5 mmHg or less for 20 minutes, and further to 260 ° C for 40 minutes under vacuum of 0.3 mmHg or less. Polycondensation reaction. Under a nitrogen gas stream, it was cooled to 220 ° C, and 50.6 parts of trimellitic anhydride was poured and reacted for 30 minutes to obtain a polyester resin. The composition of the obtained copolymerized polyester (P-6) is terephthalic acid / isophthalic acid / trimellitic acid / / ethylene glycol / 2 - methyl - 1,3-propanediol = 48 / 48 / 4//85/15 (mole ratio), a number average molecular weight of 20,000, an acid value of 250 eq/ton, and a glass transition temperature of 62 °C. The results are shown in Table 1.

Synthesis of polyurethane resin Synthesis of polyurethane resin (U-1)

In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 1000 parts of polyester polyol (P-1), 80 parts of neopentyl glycol (NPG), and 90 parts of dimethyloldine were poured into the synthesis example. After the acid (DMBA), 815 parts of ethylene glycol acetate and 272 parts of ethylene glycol butyrate were fed and dissolved at 85 °C. Thereafter, 460 parts of 4,4'-diphenylmethane diisocyanate (MDI) was added, and after reacting at 85 ° C for 2 hours, 0.5 part of dibutyltin dilaurate as a catalyst was added, and further at 85 ° C. It was allowed to react for 4 hours. Next, 1455 parts of ethyl carbitol acetate and 485 parts of butyl cellosolve acetate were used to dilute the solution to obtain a polyurethane resin (U-1). The solid concentration of the obtained polyurethane resin solution was 35 (% by mass). The resin solution obtained in this manner was dropped on a polypropylene film, and stretched using a thin coater made of stainless steel to obtain a film of a resin solution. The film was allowed to stand in a hot air dryer adjusted to 120 ° C for 3 hours to volatilize the solvent, and then the resin film was peeled off from the polypropylene film to obtain a film-like dried resin film. The thickness of the dried resin film was about 30 μm. The dried resin film was used as a sample resin of a polyurethane resin (U-1), and various resin physical properties were evaluated, and the number average molecular weight was 55,000, the acid value was 380 eq/ton, and the Tg was 70 °C. The respective components and resin physical properties at the time of producing the polyurethane resin (U-1) are shown in Table 2.

Synthesis of polyurethane resin (U-2) to (U-6)

The synthesis of the polyurethane resin (U-2) to (U-6) is carried out by substituting a compound having a group reactive with a polyester polyol or an isocyanate and a polyisocyanate into the materials shown in Table 2, and utilizing The synthesis method of the polyurethane resin (U-1) was synthesized in the same manner. The respective components and resin physical properties at the time of producing the polyurethane resin (U-2) to (U-6) are shown in Table 2. Further, the solid content of the polyurethane resin solutions (U-2) to (U-6) is in the range of 35 ± 1 (% by mass).

The abbreviations disclosed in Table 2 are as follows:

DMBA: dimethylolbutanoic acid,

DMPA: dimethylolpropionic acid,

NPG: neopentyl glycol,

DMH: 2-butyl-2-ethyl-1,3-propanediol,

MDI: 4,4'-diphenylmethane diisocyanate,

IPID: Isophorone diisocyanate.

Synthesis of polyurethane resin (U-7)

In a reaction vessel equipped with a stirrer, a condenser and a thermometer, 1000 parts of the polyester polyol (P-1) of the synthesis example, 1500 parts of the polyester polyol (P-5), and 1 part of 6 of 6 were poured. - hexanediol (1,6HD), 150 parts of neopentyl glycol (NPG), 30 parts of dimethylolbutanoic acid (DMBA), adding 1,730 parts of ethylene glycol acetate as a solvent, 577 parts Butanediol acetate was dissolved at 85 °C. Then, 810 parts of 4,4'-diphenylmethane diisocyanate (MDI) was added, and after reacting for 2 hours, 0.8 part of dibutyltin dilaurate was added, and the reaction was further carried out at 85 ° C for 4 hours. Next, it was diluted with 3089 parts of ethyl carbitol acetate and 1030 parts of butyl cellosolve acetate to obtain a polyurethane resin (U-7). The solid concentration of the obtained polyurethane resin solution was 35 mass%. The number average molecular weight was 40,000, the acid value was 60 eq/ton, and the Tg was -12 °C. Table 3 shows the respective components and resin physical properties at the time of producing the polyurethane resin (U-7).

Synthesis of polyurethane resin (U-8) to (U-11)

The synthesis of the polyurethane resin (U-8) to (U-11) is carried out except that the compound having a group reactive with the polyester polyol or the isocyanate and the polyisocyanate are changed to those shown in Table 3. It was synthesized in the same manner as the synthesis method of the polyurethane resin (U-7). Table 3 shows the respective components and resin physical properties at the time of producing the polyurethane resin (U-8) to (U-11). Further, the solid content of the polyurethane resin (U-8) to (U-11) is in the range of 35 ± 1 (% by mass).

The abbreviation in Table 3 is the same as in Table 2, and the 1,6 HD system means 1,6-hexanediol.

Synthesis of polyurethane resin (U-12)

100 parts of polyester resin (P-7), 112 parts of diethylene glycol monoethyl ether acetate, and 0.1 part of dibutyltin dilaurate were fed into a four-necked flask equipped with a cooler. Dissolved at 80 ° C. Next, 12.4 parts of 4,4'-diphenylmethane diisocyanate (MDI) was fed, and polymerization was carried out at 80 ° C under a nitrogen-oxygen stream until the remaining isocyanate was used up. After completion of the reaction, the mixture was diluted with diethylene glycol monoethyl ether to adjust the solid content to 25%. The obtained polyurethane resin had a glass transition temperature of 58 ° C, a reducing viscosity of 1.8 dl / g, a number average molecular weight of 58,000, an acid value of 10 eq / ton, and a varnish viscosity of 320 dPa ‧ s.

Example 1

2,858 parts of a polyurethane resin solution (U-1) having a solid content of 35% by mass (1,000 parts in terms of solid content) and 6,540 parts of flaky silver powder SF70A made by Ferro Japan, as carbon black 76 parts of the ECP600JD manufactured by Lion Co., Ltd., 76 parts of graphite BF manufactured by Zhongyue Graphite Industry Co., Ltd., and 58 parts of MK Conc manufactured by Kyoeisha Chemical Co., Ltd. as a leveling agent, as a dispersing agent. 16 copies of Disperbyk 2155 made by BYK Chemie Japan Co., Ltd., 640 parts of ethylene glycol acetate (ECA) as solvent, and 210 parts of butyl carbitol acetate (BCA), which were passed through a three-roller mixer. Disperse 3 times. The amounts of the respective components in the entire solution are shown in Table 4. The PET film obtained by annealing the obtained silver paste was used as a substrate, and after printing by the method specified in 5. The adhesion test, it was dried at 120 ° C for 30 minutes. The obtained coating film physical properties were 4.9 × 10 ^-5 Ω ‧ cm, adhesion 100/100, and pencil hardness H were good, and the results are shown in Table 4.

On the other hand, the substrate was printed, dried, and evaluated by the above-described method in the adhesion test using a crystalline ITO film KA500 (manufactured by Oikei Co., Ltd.). In addition, environmental tests were carried out. The evaluation results are shown in Table 4.

Examples 2 to 7

A silver paste was prepared in the same manner as in Example 1 by the components shown in Table 4 and blended, and a PET film which had been annealed was used as a substrate to prepare a coating film. The coating film properties are shown in Table 4.

In the same manner as in Example 1, a crystalline ITO film KA500 (manufactured by Oikei Co., Ltd.) was used, and printing, drying, and evaluation were carried out by the above-described method in the adhesion test. In addition, environmental tests were carried out. The evaluation results are shown in Table 4.

In any of the examples, good film properties were obtained under the conditions of an oven at a low temperature of 120 ° C for 30 minutes. In addition, adhesion to ITO, adhesion after environmental test, and blocking resistance are also good.

Further, the conductive powders, additives, and solvents shown in Table 4 were used as follows:

Silver powder 1: SF70A made by Ferro Japan

Silver powder 2: AgC-2011 made by Fukuda Metal Foil Industry Co., Ltd.

Carbon black: Ketjen ECP600JD made by Lion

Graphite powder: Graphite BF made by China-Vietnam Graphite Industry Co., Ltd.

Hardener: MF-K60X made by Asahi Kasei Chemicals Co., Ltd.

Hardening catalyst: KS1260 made of common medicine (stock),

Flat agent: MK Conc of Gongrongshe Chemical Co., Ltd.

Dispersant 1: Dieperbyk 2155, manufactured by BYK Chemie Japan Co., Ltd.

Dispersant 2: Dieperbyk 180, manufactured by BYK Chemie Japan Co., Ltd.

ECA: ethylene glycol acetate manufactured by Daicel Chemical Industry Co., Ltd.

BCA: Butanediol acetate manufactured by Daicel Chemical Industry Co., Ltd.

Comparative example 1

The blending of 2,858 parts (1,000 parts in terms of solids) has adjusted the polyester resin (P-6) to a solid concentration of 35 mass% (ethylene glycol acetate: butanediol acetate = 75:25 (mass ratio) a solution of 6,540 parts of flaky silver powder SF70A made by Ferro Japan, 76 parts of Ketjen ECP600JD made by Lion of 76 parts of carbon black, and 76 parts of graphite BF made by Zhongyue Graphite Industry Co., Ltd. 58 parts of MK Conc manufactured by Kyoeisha Chemical Co., Ltd. as a flattening agent, 16 parts of Diseperbyk 2155 made by BYK Chemie Japan as a dispersing agent 1, 640 parts of ethylene glycol acetate as a solvent, 210 The butyl carbitol acetate was dispersed three times using a cooled three-roll mixer. The amounts of the respective components in the entire solution are shown in Table 5. The PET film subjected to the annealing treatment of the obtained silver paste was printed by the method described in 5. The adhesion test, and then dried at 120 ° C for 30 minutes. The coating film properties obtained were 9.2 × 10 ^-5 Ω ‧ cm, adhesion 100/100, and pencil hardness HB were good. The results are shown in Table 5.

On the other hand, the substrate was printed, dried, and evaluated by the method described in the 5. Adhesion test using a crystalline ITO film KA500 (manufactured by Oikei Co., Ltd.). In addition, environmental tests were carried out. The evaluation results are shown in Table 5.

Comparative Examples 2 to 7

A silver paste was prepared in the same manner as in Example 1 by the components shown in Table 5 and blended, and a PET film which had been annealed was used as a substrate to prepare a coating film. The coating film properties are shown in Table 5.

Further, regarding Comparative Example 6, since it was difficult to use high-viscosity printing, the subsequent evaluation was stopped.

In the same manner as in Comparative Example 1, a crystalline ITO film KA500 (manufactured by Oike Industrial Co., Ltd.) was used, and printing, drying, and evaluation were carried out by the method described in 5. Adhesion test. In addition, environmental tests were carried out. The evaluation results are shown in Table 5.

In any of the comparative examples, the temperature of the oven was 120 ° C × 30 minutes for a short period of time, and the coating property of the ITO substrate was poor. In addition, ITO adhesion, blocking resistance, and the like after the environmental test were also poor.

The evaluation results are shown in Table 5. Further, the conductive powder, the additive and the solvent of Table 5 at the time of display were the same as those of Table 4.

Claims (14)

A conductive paste comprising: (A) component, an adhesive resin composed of a polyurethane resin having an acid value of 50 to 500 eq/ton and a glass transition temperature of 60 to 150 ° C; (B) The component is a metal powder; and the component (C) is an organic solvent. The conductive paste of claim 1, wherein the component (A) is a polyurethane having a structure obtained by addition polymerization of (A1), (A2) and (A3) Adhesive resin composed of resin: (A1) an amorphous polyalcohol having a number average molecular weight of 1,000 to 10,000 and a glass transition temperature of 30 to 80 ° C, (A2) having a number average molecular weight of less than 1,000 and having 2 in one molecule One or more compounds capable of reacting with an isocyanate, and (A3) a polyisocyanate. The conductive paste of claim 1, wherein the component (A) is obtained by having a structure obtained by addition polymerization of (A1), (A2), (A3) and (A4) An adhesive resin composed of a urethane resin: (A1) an amorphous polyalcohol having a number average molecular weight of 1,000 to 10,000 and a glass transition temperature of 30 to 80 ° C, and (A2) a number average molecular weight of less than 1,000 and one a compound having two or more functional groups capable of reacting with an isocyanate in a molecule, (A3) a polyisocyanate, and (A4) an amorphous polyalcohol having a number average molecular weight of 1,000 to 10,000 and a glass transition temperature of less than 30 °C. The conductive paste according to claim 2 or 3, wherein the amorphous polyalcohol (A1) is an amorphous polyester polyol, and the amorphous polyester polyol is a polycarboxylic acid (polycarboxylic acid). When the acid) and the total polyol component are each 100 mol%, the aromatic dicarboxylic acid is 60 mol% or more in all the polycarboxylic acid components, and the carbon in the main chain is contained in all the polyalcohol components. The diol having a number of 4 or less is 60 mol% or more. The conductive paste according to claim 2 or 3, wherein the functional group reactive with the isocyanate in the compound (A2) is a hydroxyl group or an amine group. The conductive paste of claim 2 or 3, wherein the compound (A2) further contains a carboxyl group. The conductive paste according to any one of claims 1 to 3, wherein the component (B) further contains a conductive powder other than the metal powder. The conductive paste according to any one of claims 1 to 3, wherein the content of the component (B) is from 400 to 1,900 parts by mass relative to 100 parts by mass of the binder resin (A). The conductive paste according to any one of claims 1 to 3, wherein the content of the component (C) is from 150 to 500 parts by mass relative to 100 parts by mass of the binder resin (A). A conductive film comprising a conductive paste as disclosed in any one of claims 1 to 9. A conductive laminate which is laminated on a transparent conductive layer as in the conductive film of claim 10 of the patent application. The conductive laminate of claim 11, wherein the transparent conductive layer is an ITO (indium tin oxide) film comprising indium tin oxide as a main component. A touch panel using the conductive laminate as claimed in claim 11 or 12. A method for producing a conductive film, comprising: a step of coating or printing a conductive paste according to any one of claims 1 to 9 on a substrate; and heating at 80 to 150 ° C .