JP6767089B2 - Conductive pastes, conductive coatings, conductive circuits, conductive laminates and touch panels - Google Patents

Description

The present invention relates to a conductive paste and its use, and more specifically, a conductive paste having excellent fine line printing suitability, a conductive circuit using the conductive paste, a conductive coating film, and the conductive coating film being a transparent conductive layer. The present invention relates to a conductive laminate laminated on top and a touch panel using the conductive laminate.

A wide range of transparent touch panels that can be operated by touching the screen with a finger or a dedicated pen, such as ATMs, car navigation systems, game consoles, station ticket vending machines, copiers, museum commentary terminals, and convenience store information terminals. It is used for various purposes and is becoming more widespread. The transparent touch panel is configured to form a switch by superimposing two transparent conductive thin films. As a transparent conductive thin film of a transparent touch panel, an indium tin oxide film (hereinafter sometimes abbreviated as ITO film) is attached to a substrate such as a polyester film or glass by a vapor deposition method or a sputtering method, and the ITO film is etched. It is generally formed by patterning.

There are various types of touch panels, and the resistive film method and the capacitance method are typical methods. In recent years, the capacitance method, which has been attracting attention with the spread of smartphones and tablet PCs, detects the discharge phenomenon caused by touching the panel with a finger or a dedicated pen and identifies the touched position on the panel. The feature of the resistive film method is that it can detect multiple points. In order to perform multipoint sensing with high resolution, it is necessary to form a large number of electrode circuit wirings as compared with the conventional resistance film method. Furthermore, in recent years, there has been an increasing demand for a narrower frame portion in which electrode circuit wiring is arranged in order to make the display screen larger and due to product design requirements. Against this background, it is required to form a large number of wiring electrodes at high density, and the demand for high-thin wire electrode circuit wiring is becoming stronger.

In order to form a large number of electrode circuit wirings at high density, thin wirings may be arranged at short intervals. A photolithography method can be mentioned as a construction method for that purpose, but the environmental load due to the waste liquid treatment is large, the process is complicated, and there are many problems including the cost viewpoint. Further, since the conductive circuit formed by the above photolithography method is formed only of a metal such as aluminum or copper, there is a problem that it is vulnerable to a physical impact such as bending. In addition, although glass is the main base material used in the photolithography method due to its usage environment, there is a demerit that the selectivity of the base material is limited in the present day when the weight of the touch panel is required to be reduced.
On the other hand, the printing method has excellent substrate selectivity, and forms conductive patterns on various substrates regardless of the substrate such as glass, ITO film, etching film obtained by etching a part of ITO, PET film, polyimide film, etc. can do. Further, the printing method has advantages in terms of cost and simplicity of equipment, and if the printing method can form fine lines using a conductive paste, it will be extremely advantageous. Further, since the conductive paste uses a binder resin as a binder with the base material, it has an advantage against physical impact such as bending. However, in the printing method, in order to form a thin conductive pattern using the conductive paste, the fine line suitability of the conductive paste is required.

The line width required for the resistance film type electrode circuit wiring is such that the line and space widths (hereinafter abbreviated as L / S) are often 200 μm (200/200 μm) or more, respectively, and a relatively coarse conductive pattern is formed. It was sufficient if it could be formed, but with the spread of capacitive touch panels, the demand for L / S in recent years has become 100/100 μm or less, and in some cases L / S is required to be 50/50 μm or less. The demand for fine wire suitability is increasing.

Therefore, various studies have been conducted on a method for forming a conductive pattern at low cost and without generating harmful waste liquid or the like. Above all, the conductive paste is filled in a printing plate having a concave pattern, and the filled conductive paste is received by a printing blanket having a silicone rubber sheet on the surface, and then from the printing blanket onto the substrate to be printed. The gravure offset printing method, which is a method of transferring a conductive paste to print and form an electrode pattern, is attracting attention as an alternative method to the photolithography method because it is possible to form a fine conductive pattern with high accuracy. ing.

As a method of forming a conductive pattern by using a gravure offset printing method, a method of transferring a conductive ink to a transfer target made of a glass substrate to produce a coating film is conventionally known (see, for example, Patent Document 1). .. However, this conventional technology uses conductive ink designed for application to glass substrates that can be sintered at high temperatures, and is not compatible with touch panels using ITO films provided on PET films and the like. There was a problem that it was difficult.

As described above, it is possible to form fine lines with high accuracy by the gravure offset printing method, but there is a strong demand for a heat treatment process at a low temperature from the viewpoint of energy saving in the processing process and heat resistance of the film substrate. It is required to develop the physical properties of the coating film by a lower heat treatment of 150 ° C. or lower. Furthermore, with the recent miniaturization and generalization of touch panels, the environment in which they are used and the frequency of use have become more diverse than before, so the required forming electrodes have even higher environmental reliability and durability. I need something.

Japanese Patent No. 5088063

The present invention has been made against the background of the problems of the prior art. That is, an object of the present invention is to have fine line printability of 50 μm or less, excellent adhesion to an ITO film in a conductive pattern formed by a low temperature process of 150 ° C. or less, and further to provide environmental reliability and high durability. The purpose is to provide a conductive paste that can be realized.

As a result of diligent studies to achieve such an object, the present inventor has made fine line printing in gravure offset printing by containing two or more kinds of thermoplastic binder resins having different number average molecular weights and a curing agent in the conductive paste. It was found that the conductive pattern formed by a low temperature process of 150 ° C. or lower can impart properties and has excellent adhesion to the ITO film, and can maintain environmental reliability and high durability.

That is, the present invention has the following configuration.
(1) A conductive paste containing at least a thermoplastic resin (A), a thermoplastic resin (B), a curing agent (C), a conductive powder (D), and an organic solvent (E), which is a thermoplastic resin (A). ) Is 4.0 times or less the weight ratio of the thermoplastic resin (B), and the thermoplastic resin (A) has a weight average molecular weight of 10,000 or more and a glass transition temperature of -10 to 150 ° C. And / or a conductive paste which is a polyester resin, further the thermoplastic resin (B) is an amorphous polyol, and has a number average molecular weight of 500 to 6,000.
(2) The conductive paste according to (1), wherein the average particle size (D50) of the conductive powder (D) is at least 7 μm or less.
(3) The conductive paste according to (1) to (2), wherein the thermoplastic resin (B) is a polyester polyol and / or a polyether polyol, and / or a polycarbonate polyol.
(4) The conductive paste according to any one of claims 1 to 3, wherein the acid value of the non-volatile organic component in the heat treatment at 130 ° C. for 30 minutes is 20 to 500 eq / ton.
(5) The curing agent (C) is an isocyanate compound, and the mixing amount of the curing agent (C) with respect to the thermoplastic resin (B) is such that the curing agent (C) is mixed with the hydroxyl group of the thermoplastic resin (B). The conductive paste according to any one of (1) to (4), wherein the isocyanate group of C) is 20 to 200 mol%.
(6) Described in any one of (1) to (5), wherein the organic solvent (E) has a boiling point of 100 ° C. or higher and the weight fraction with respect to the total weight of the conductive paste is 25% by weight or less. Conductive paste.
(7) The conductive paste according to any one of (1) to (6), wherein the conductive powder (D) is mainly composed of silver.
(8) Gravure offset printing (The conductive paste is filled in a printing plate having a concave pattern, and the filled conductive paste is received by a printing blanket having a silicone rubber sheet on the surface, and then printed from the printing blanket. The conductive paste according to any one of (1) to (7), which is used in a method of transferring a conductive paste onto a substrate to print and form an electrode pattern).
(9) The conductive pace according to any one of (1) to (7) above is gravure-offset printed (the conductive paste is filled in a printing plate having a concave pattern, and the filled conductive paste is applied to the surface. After receiving into a printing blanket having a silicone rubber sheet, the obtained conductive coating film is dried (from the method of transferring the conductive paste from the printing blanket onto the substrate to be printed and printing and forming the electrode pattern). Printed matter obtained by and / or curing.
(1O) The printed matter according to (9), wherein the line / space pitch is 100 μm or less.
(11) A conductive laminate obtained by laminating the printed matter according to (9) to (10) on a transparent conductive layer. (12) A touch panel using the conductive laminate according to (11) above.

The conductive paste of the present invention uses at least two types of thermoplastic binder resins having different number average molecular weights and a curing agent to form a fine line gravure offset printability of the conductive paste and conductivity formed by a low temperature process of 150 ° C. or lower. In the pattern, it has excellent adhesion to the ITO film, and also has both environmental reliability and high durability.

Hereinafter, the conductive paste according to the embodiment of the present invention will be described.
The conductive paste of the present embodiment is a conductive paste containing at least a thermoplastic resin (A), a thermoplastic resin (B), a curing agent (C), a conductive powder (D), and an organic solvent (E). , The weight ratio of the thermoplastic resin (A) to that of the thermoplastic resin (B) is 4.0 times or less, the weight average molecular weight of the thermoplastic resin (A) is 10,000 or more, and the glass transition temperature is −10 to 10. It is a polyurethane resin or a polyester resin at 150 ° C., and the thermoplastic resin (B) is an amorphous polyol and has a number average molecular weight of 500 to 6,000.

The thermoplastic resin (A) and the thermoplastic resin (B) used in the conductive paste of the present invention have different number average molecular weights, and the thermoplastic resin (A) has a weight ratio with respect to the thermoplastic resin (B). Is 4.0 times or less. When such two types of thermoplastic resins having different number average molecular weights are used as the binder resin, the molecular weight distribution curve in the GPC analysis often has a peak of more than two mountains. This is because the peak tops of the molecular weight distributions of the respective thermoplastic resins are different, and as a result, the molecular weight distribution becomes broader than when a single resin is used. That is, the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of the entire binder resin is larger than that of the single resin, which is environmental stability, high durability and printability. It contributes to the realization of both.

The conductive paste of the present invention may contain three or more types of resins as long as it does not impair environmental stability, durability and printability.

The type of the thermoplastic resin (A) is not particularly limited, but is preferably a polyurethane resin or a polyester resin. By using these resins as the thermoplastic resin (A), the durability of the coating film can be ensured when the conductive paste is applied or cured after printing, and the conductive powders such as the metal powder inside the coating film are mutually conductive powders. High conductivity can be exhibited as the distance increases.

When the thermoplastic resin (A) is a polyester resin, the aromatic dicarboxylic acid in the total acid component is preferably 20 mol% or more, more preferably 35 mol% or more, still more preferably 50 mol% or more. If the amount of the aromatic dicarboxylic acid is less than 20 ru%, the strength of the coating film is lowered, and the durability such as low temperature bending resistance, heat resistance, moisture resistance and heat impact resistance may be lowered. The preferred upper limit for the aromatic dicarboxylic acid is 100 mol%.

Examples of the aromatic dicarboxylic acid copolymerized with the polyester resin include terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid. Of these, it is preferable to use terephthalic acid and isophthalic acid in combination in terms of physical properties and solvent solubility.

Examples of other dicarboxylic acids that copolymerize with polyester include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, and azelaic acid, dibasic acids having 12 to 28 carbon atoms, and 1 , 4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrohydride phthalic acid, 3-methylhexahydrohydride phthalic acid, 2-methylhexahydrohydride phthalic acid, Dicarboxyhydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalenedicarboxylic acid, alicyclic dicarboxylic acid such as tricyclodecanedicarboxylic acid, hydroxycarboxylic acid such as hydroxybenzoic acid, lactic acid Examples of the acid include sebacic acid, adipic acid, azelaic acid, and 1,4-cyclohexanedimethanol from the viewpoint of moisture resistance.

Further, as long as the content of the invention is not impaired, polyvalent carboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid, and sulfonic acids such as 5-sulfoisophthalic acid sodium salt. A metal base-containing dicarboxylic acid may be used in combination. Further, after the polyester resin is polymerized, an acid anhydride such as trimellitic anhydride or phthalic anhydride may be added afterwards to impart an acid value.

As the glycol component copolymerized with the polyester resin, the following known glycols can be used. For example, ethylene glycol, neopentyl glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 2,2-die 1,3-propanediol, 2-methyl- 1,3-Propanediol, 1,4-butanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1 , 5-Pentanediol, 1,6-Hexanediol, 3-Methyl-1,5-Pentanediol, 2-Methyl-1,5-Pentanediol, 1,9-Nonandiol, 1,10-Decandiol, etc. Alicyclic glycols such as alkylene glycol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, tricyclodecane glycol, dimerdiol, diethylene glycol, polyethylene glycol, polytetramethylene glycol. Polyether-based diols and the like can be mentioned. Further, an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of bisphenol F, and a polyvalent polyol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and polyglycerin may be used in combination.

The polyester resin preferably has no melting point (indicates that it is amorphous) because of its adhesiveness, flexibility, solvent solubility, and the like. Having no melting point as used herein means that it does not show a clear melting peak when measured using a differential scanning calorimeter (DSC).

When the thermoplastic resin (A) is a polyurethane resin, it is synthesized by a known method by blending an amorphous polyol, a polyisocyanate compound, and if necessary, a chain extender. Since polyurethane resin can be polymerized with a solution, it is easier to obtain a polyurethane resin having a higher molecular weight than polyester resin. Preferred examples of the amorphous polyol include (meth) acrylic polyol, polycarbonate diol, polybutadiene polyol, polyester polyol, polyether polyol and the like. Polycarbonate diols, polyether polyols, and polyester polyols are more preferable than adhesiveness, bending resistance, and durability, and polyester polyols are even more preferable from the viewpoint of freedom of molecular design.

When the amorphous polyol used when the thermoplastic resin (A) is a polyurethane resin is a polyester polyol, the preferable components are the same as those of the polyester resin described above, but the molecular weight is preferably 1,000 or more, and the upper limit is It is preferably 20,000 or less, more preferably 10,000 or less.

When synthesizing a polyurethane resin, the compound that can be used as a chain extender is preferably one having a hydroxyl group and an amino group, and may have either one or both. Specific examples of the components include dimethylolbutanoic acid and dimethylolpropionic acid, as well as 1,2-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 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-Diol-3-hydroxypropyl-2', 2'-dimethyl-3'-hydroxypropanate, 2-normalbutyl-2-ethyl-1,3-propanediol, 3-ethyl-1,5-pentane Diol, 3-propyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol, 3-phenyl-1,5-pentanediol, 2, Compounds having two hydroxyl groups in one molecule, such as 5-dimethyl-3-sodium sulfo-2,5-hexanediol and dimerdiol (for example, PRIPOOL-2033 manufactured by Unichema International Co., Ltd.), trimethylolethane, trimethylol, etc. Polyhydric alcohols such as propane, glycerin, pentaerythritol, polyglycerin, amino alcohols having one or more hydroxyl groups and amino groups in one molecule such as monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, 1,6-hexanediamine , 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol and other aliphatic diamines and metaxylene diamines, 4,4'-diamino Examples thereof include compounds having two amino groups in one molecule such as aromatic diols such as diphenylmethane, 3,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether. These compounds may be used alone or in combination of two or more without any problem.

The polyisocyanate compound used in synthesizing the polyurethane resin is not particularly limited, but aromatic, aliphatic, alicyclic diisocyanates and the like are preferable. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, m-phenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate. , 2,6-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diphenylene diisocyanate, 4,4'-diisocyanide diphenyl ether, 1,5-naphthalene diisocyanate, m-xylene Examples thereof include diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate.

The number average molecular weight (Mn (A)) of the thermoplastic resin (A) is in the range of 10,000 to 70,000, more preferably 10,000 to 40,000, still more preferably 10,000 to 30,000. Is. If Mn (A) is too low, it is not preferable in terms of durability and environmental stability. On the other hand, if Mn (A) is too high, the cohesive force of the resin is increased and the durability and the like are improved, but the fine line printing suitability in gravure offset printing is remarkably lowered.

The glass transition temperature of the thermoplastic resin (A) is preferably −10 ° C. or higher, more preferably 0 ° C. or higher. If the glass transition temperature is too low, the resin softens at high temperatures, which may reduce the reliability of the conductive thin film formed from the paste, and also induces a decrease in surface hardness due to tackiness in the manufacturing process and / Alternatively, the paste-containing component may be transferred to the contacting side during use, which may reduce the reliability of the conductive thin film. On the other hand, the glass transition temperature of the thermoplastic resin (A) is preferably 150 ° C. or lower, more preferably 120 ° C. or lower, and more preferably 100 ° C. or lower in consideration of printability, adhesion, solubility, paste viscosity, printability and the like. More preferred.

In the present invention, it is preferable that the solid organic component of the conductive paste contains a carboxyl group and the amount of the carboxyl group (acid value) is within a predetermined range. As a preferred embodiment, it is preferable that the thermoplastic resin (A) has an acid value in a specific range. By using a resin having an acid value in a specific range as the thermoplastic resin (A), the adhesion of the formed conductive thin film to the substrate can be remarkably improved. The acid value of the thermoplastic resin (A) is preferably 20 to 500 eq / ton, more preferably 30 to 350 eq / ton. If the acid value of the thermoplastic resin (A) is too low, the adhesion between the formed conductive thin film and the base material tends to be low. On the other hand, if the acid value of the thermoplastic resin (A) is too high, the water absorption of the formed conductive thin film becomes high, and the hydrolysis of the thermoplastic resin may be promoted by the catalytic action of the carboxyl group. , It tends to lead to a decrease in the reliability of the conductive thin film.

It is also possible to add a diol compound having a carboxy group to the conductive paste. Examples include dimethylolalkanoic acids such as dimethylolpropionic acid and dimethylolbutanoic acid, and amine salts of these dimethylolalkanoic acids. By adding these diol compounds having a carboxy group, the carboxy group can be easily introduced into the cured coating film, and the adhesion to the ITO film can be improved. Further, the diol compound having a carboxy group is preferably added so that the acid value of the non-volatile organic component in the heat treatment at 130 ° C. for 30 minutes becomes 20 to 500 eq / ton, more preferably 30 to 350 eq / ton. ..

The type of the thermoplastic resin (B) is not particularly limited, but it is preferably an amorphous polyol having a functional group capable of reacting with two or more isocyanate groups in one molecule. Examples include polyester polyols, polyether polyols, and polycarbonate polyols, and polyester polyols are more preferable from the viewpoint of the degree of freedom in molecular design. By blending the thermoplastic resin (B) having a lower number average molecular weight than the thermoplastic resin (A), the transferability of the conductive paste from the silicone blanket to the film during gravure offset printing can be improved. , Fine line printability is remarkably improved.

When a polyester polyol is used as the thermoplastic resin (B), preferred dicarboxylic acid components include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, and sebacic acid. Aliphatic dicarboxylic acids such as dodecanedicarboxylic acid and azelaic acid, dibasic acids with 12 to 28 carbon atoms, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl Hexahydrophthalic anhydride, 3-methylhexahydrophthalic acid, 2-methylhexahydrophthalic acid, dicarboxyhydrogenylated bisphenol A, dicarboxyhydrogenated bisphenol S, dimeric acid, hydrogenated dimeric acid, hydrogenated naphthalenedicarboxylic acid Examples thereof include alicyclic dicarboxylic acids such as acids and tricyclodecanedicarboxylic acids, and hydroxycarboxylic acids such as hydroxybenzoic acid and lactic acid. These may be used alone or in combination of two or more. Of these, it is preferable to use terephthalic acid and isophthalic acid in combination because of their physical properties and solvent solubility.

Further, as long as the content of the invention is not impaired, polyvalent carboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid, and sulfonic acids such as 5-sulfoisophthalic acid sodium salt. A metal base-containing dicarboxylic acid may be used in combination. Further, after the polyester polyol is polymerized, an acid anhydride such as trimellitic anhydride or phthalic anhydride may be added afterwards to impart an acid value.

Further, as the glycol component when the polyester polyol is used, the known glycols shown below can be used. For example, ethylene glycol, neopentyl glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 2,2-die 1,3-propanediol, 2-methyl- 1,3-Propanediol, 1,4-butanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1 , 5-Pentanediol, 1,6-Hexanediol, 3-Methyl-1,5-Pentanediol, 2-Methyl-1,5-Pentanediol, 1,9-Nonandiol, 1,10-Decandiol, etc. Alicyclic glycols such as alkylene glycol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, tricyclodecane glycol, dimerdiol, diethylene glycol, polyethylene glycol, polytetramethylene glycol. Polyether-based diols and the like can be mentioned. Further, an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of bisphenol F, and a polyvalent polyol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and polyglycerin may be used in combination. Further, for example, polycaprolactone polyols obtained by ring-opening polymerization using ε-caprolactone as a polyhydric alcohol can be mentioned.
These may be used alone or in combination of two or more.

When the thermoplastic resin (B) is a polyether polyol, for example, a poly obtained by adding a single or a mixture of alkylene oxides such as ethylene oxide and propylene oxide to a single or a mixture of polyhydric alcohols such as glycerin and propylene glycol. Obtained by polymerizing ether polyols, polytetramethylene glycols, polyether polyols obtained by reacting alkylene oxide with polyfunctional compounds such as ethylenediamine and ethanolamines, and acrylamide and the like using these polyethers as a medium. So-called polymer polyols and the like are included.

When the thermoplastic resin (B) is a polycarbonate polyol, it may be a polycarbonate diol containing a repeating unit derived from one or more linear aliphatic diols as a constituent unit, or one or more alicyclic diols. Examples thereof include a polycarbonate diol containing a repeating unit derived from a repeating unit as a constituent unit, or a polycarbonate diol containing a repeating unit derived from both of these diols as a constituent unit. Specific constituents include 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol and the like as linear aliphatic diols. , 1,4-Cyclohexanedimethanol and the like can be mentioned as the alicyclic diol.

The number average molecular weight of the thermoplastic resin (B) is preferably 500 to 6,000, more preferably 500 to 4,000. If the number average molecular weight is too low, the viscosity of the conductive paste will be low and the fine line printing suitability will be lowered, which is not preferable. On the other hand, if the number average molecular weight is too high, the viscosity of the conductive paste is high, and the suitability for fine line printing in gravure offset printing is significantly reduced. Further, the thermoplastic resin (B) may have an acid value within a predetermined range in order to improve the adhesion to the ITO film.

The weight ratio of the thermoplastic resin (A) to the thermoplastic resin (B) needs to be 4.0 times or less, more preferably 3.5 times or less, still more preferably 3.0 times or less. .. If the weight ratio is too high, the viscosity of the conductive paste is high, and the suitability for fine line printing in gravure offset printing is significantly reduced.

In the conductive paste of the present invention, polyurethane resins other than the thermoplastic resins described above, polyester resins, epoxy resins, phenol resins, acrylic resins, styrene-acrylic resins, styrene-butadiene copolymers, polystyrenes, polyamide resins, There are no restrictions on the combined use of polyamideimide resin, polycarbonate resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, polyvinyl butyral resin, cellulose, modified cellulose and the like.

The type of the curing agent (C) capable of reacting with the binder resin of the present invention is not particularly limited, but an isocyanate compound is particularly preferable from the viewpoint of adhesiveness, bending resistance, curability and the like. Further, as these isocyanate compounds, it is preferable to use one in which an isocyanate group is blocked because the storage stability is improved. Examples of the curing agent other than the isocyanate compound include amino resins such as methylated melamine, butylated melamine, benzoguanamine and urea resin, and known compounds such as acid anhydrides, imidazoles, epoxy resins and phenol resins. Known catalysts or accelerators selected according to the type of these curing agents can also be used in combination. The compounding ratio of the thermoplastic resin (B) and the curing agent (C) is 20 to 200 mol% of the functional group capable of reacting with the hydroxyl group of the curing agent (C) with respect to the hydroxyl group of the thermoplastic resin (B). It is preferably 50 to 150 mol%, more preferably 75 to 125 mol%.

Examples of the isocyanate compound that can be blended in the conductive paste of the present invention include aromatic or aliphatic diisocyanates, trivalent or higher polyisocyanates, and may be either low molecular weight compounds or high molecular weight compounds. For example, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, hydride diphenylmethane diisocyanate, hydride xylylene diisocyanate, dimerate diisocyanate, isophorone diisocyanate and the like. Alicyclic diisocyanates, or trimerics of these isocyanate compounds, and excess amounts of these isocyanate compounds and, for example, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine. Examples thereof include terminal isocyanate group-containing compounds obtained by reacting with low molecular weight active hydrogen compounds such as, various polyester polyols, polyether polyols, high molecular weight active hydrogen compounds of polyamides, and the like. Examples of the isocyanate group blocking agent include phenols such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol, and oximes such as acetoxime, methylethylketooxime, and cyclohexanone oxime. , Methanol, ethanol, propanol, butanol and other alcohols, ethylene chlorohydrin, 1,3-dichloro-2-propanol and other halogen-substituted alcohols, t-butanol, t-pentanol and other tertiary alcohols. , Ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propyrolactam and other lactams, 3,5-dimethylpyrazole and other pyrazoles, and other aromatic amines, imides and acetylacetones. , Active methylene compounds such as acetoacetic acid ester and malonic acid ethyl ester, mercaptans, imines, imidazoles, ureas, diaryl compounds, sodium bicarbonate and the like. Of these, oximes, pyrazoles, active methylenes, imidazoles, and amines are particularly preferable from the viewpoint of curability.

The conductive powder (D) in the conductive paste of the present embodiment is used to impart conductivity in the formed conductive pattern.
As the conductive powder (D) in the present invention, precious metal powders such as silver powder, gold powder, platinum powder and palladium powder, and base metal powders such as copper powder, nickel powder, aluminum powder and brass powder are preferable. Examples thereof include plating powder obtained by plating dissimilar particles made of inorganic substances such as base metal and silica with a noble metal such as silver, and base metal powder alloyed with a noble metal such as silver. Further, as the conductive powder (D) in the present invention, a conductive powder made of a non-metal such as a carbon-based filler such as carbon black or graphite powder may be used. When carbon black and graphite powder are contained, the content of carbon black and / or graphite powder can be 25 parts by mass or less, more preferably 11 parts by mass or less with respect to 100 parts by mass of the metal powder. .. These conductive powders may be used alone or in combination. Among these, those containing silver powder alone or mainly silver powder are particularly preferable in that a coating film exhibiting high conductivity can be easily obtained.

The shape of the conductive powder (D) is not particularly limited, but examples of preferable shapes are described in known flakes (phosphorus-like), spherical, dendritic (dendrite-like), and JP-A-9-306240. As described above, a shape in which primary particles are aggregated in a three-dimensional manner (aggregated powder) and the like can be mentioned. Of these, flaky, spherical, and aggregated powders are preferable, and they may be used alone or in combination.

The particle size of the conductive powder (D) is not particularly limited, but it is preferable that the center diameter (D50) is 7 μm or less from the viewpoint of imparting fine wire suitability. When a conductive powder having a center diameter larger than 7 μm is used, the shape of the formed fine wires is poor, and the fine wires may come into contact with each other, resulting in a short circuit.

The specific resistance of the conductive coating film obtained by curing the conductive paste is preferably 5.0 × 10 ⁻² or less, more preferably 5.0 × 10 ^-3 or less, preferably 5.0 from the viewpoint of obtaining an excellent conductive circuit. × ^10-4 or less is more preferable.

The following inorganic substances can be added to the conductive paste of the present invention. Inorganic substances include various carbides such as silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, and diamond carbon lactam; boron nitride. , Various nitrides such as titanium nitride and zirconium nitride, various borides such as zirconium boride; various oxidations such as titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica and colloidal silica. Products; Various titanium acid compounds such as calcium titanate, magnesium titanate, and strontium titanate; Carbides such as molybdenum disulfide; Various fluorides such as magnesium fluoride and carbon fluoride; Aluminum stearate, calcium stearate, stearic acid Various metal soaps such as zinc and magnesium stearate; in addition, talc, bentonite, talc, calcium carbonate, bentonite, kaolin, glass fiber, mica and the like can be used. By adding these inorganic substances, it may be possible to improve printability, heat resistance, mechanical properties, and long-term durability. Above all, in the conductive paste of the present invention, silica is preferable from the viewpoint of imparting printability. That is, in the presence of silica, the viscosity can be increased by the physical cohesive force between the fillers containing silica and the pseudo-crosslinking by hydrogen bond formation. The silica to be used can be used regardless of its particle size, its hydrophilicity, and its hydrophobicity.

Further, thixotropic agents, antifoaming agents, flame retardants, tackifiers, hydrolysis inhibitors, leveling agents, plasticizers, antioxidants, ultraviolet absorbers, flame retardants, pigments and dyes can be used. Further, carbodiimide, epoxy or the like can be appropriately used as the resin decomposition inhibitor. These can be used alone or in combination.

The organic solvent (E) in the present invention preferably has a boiling point of 100 ° C. or higher and lower than 350 ° C. at 0.1013 MPa, more preferably 150 ° C. or higher and lower than 330 ° C. More preferably, the boiling point is 180 ° C. or higher and lower than 320 ° C. If the boiling point of the organic solvent (E) is too low, there is a concern that the solvent volatilizes during the paste manufacturing process or when the paste is used, and the component ratios constituting the conductive paste are likely to change. On the other hand, if the boiling point of the organic solvent is too high, a large amount of solvent may remain in the coating film when a low-temperature drying step is required (for example, 150 ° C. or lower), which causes a decrease in the reliability of the coating film. There are concerns.

Further, as the organic solvent (E), the thermoplastic resin (A), the thermoplastic resin (B) and the curing agent (C) are soluble, and the conductive powder (D) can be dispersed well. Is preferable. For example, cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, Solbesso 100, 150, 200 manufactured by Exxon Chemical, propylene glycol monomethyl ether acetate, tarpionel, butyl glycol acetate, diamylbenzene, triamylbenzene, n-dodecanol. , Diethylene glycol, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol dibutyl ether, diethylene glycol monoacetate, triethylene glycol diacetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether , Triethylene glycol monobutyl ether acetate, tetraethylene glycol, tetraethylene glycol dimethyl ether, tetraethylene glycol monobutyl ether, tripropylene glycol, tripropylene glycol monomethyl ether, tripropylene glycol monomethyl ether acetate, tripropylene glycol monobutyl ether, tripropylene glycol mono Examples thereof include butyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, benzyl butyrate, and benzyl benzoate. Examples of petroleum-based hydrocarbons include AF Solvent No. 4, 5, 6, 7, and 0 Solvent H manufactured by Nippon Oil Co., Ltd., and two of them as necessary. The above may be included.
Such an organic solvent is appropriately contained so that the conductive paste has a viscosity suitable for printing and the like.

The content of the organic solvent (E) is preferably 25 parts by weight or less, more preferably 20 parts by weight or less, based on 100 parts by weight of the total weight of the paste. If the content of the organic solvent (E) is too high, the paste viscosity becomes low, causing sagging during fine line printing.

When such a conductive paste is used for gravure offset printing, in order to obtain good printability, the density thereof should be a commercially available cone plate type viscometer (for example, RE-85 manufactured by Toki Sangyo Co., Ltd.). The measured value (measured value at 25 ° C., rotation speed 2.5 rpm, 180 seconds after the start of rotation) by the mold, cone shape angle 3 °, R14, etc. is preferably 10 to 500 Pa · s. If it is less than 10 Pa · s, the ratio of the organic solvent in the conductive paste is too large, and the transferability of the conductive paste from the printing blanket having the silicone rubber sheet on the surface to the substrate to be printed is lowered, and the printed matter is good. Will be difficult to obtain. On the other hand, if it exceeds 500 Pa · s, it is difficult to fill the printing plate, the scraping property with the doctor blade is deteriorated, and ground stains (paste adhesion to non-image areas) are likely to occur. Further, the amount of the conductive paste received from the printing plate to the blanket for printing is reduced, and the electrode pattern is broken or stringed. More preferably, it is 20 to 300 dPa · s. It is also possible to appropriately dilute at the time of printing.

The conductive paste of the present invention preferably has an F value of 60 to 95%, more preferably 75 to 95%. The F value is a numerical value indicating a filler mass part with respect to 100 parts by mass of the total solid content contained in the paste, and is represented by F value = (filler mass part / solid content mass part) × 100. The filler mass part referred to here is a mass part of the conductive powder (D), and the solid content mass part is a mass part of a component other than the solvent, and the conductive powder, the binder resin, and other curing agents and additives are all included. Including. If the F value is less than 60%, good conductivity cannot be obtained, and if it exceeds 95%, the adhesion to the substrate and / or the hardness of the conductive coating film tends to decrease, and the printability further decreases. Is inevitable.
A conductive thin film can be formed by applying or printing the conductive paste of the present invention on a substrate to form a coating film, and then volatilizing and drying the organic solvent (E) contained in the coating film. ..

By carrying out the step of volatilizing the organic solvent (E) under heating, the curing reaction proceeds, and the conductivity, adhesion, and surface hardness of the conductive thin film after drying are improved. The heating temperature is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and even more preferably 110 ° C. or higher. Further, from the viewpoint of heat resistance of the transparent conductive layer of the base and energy saving in the production process, the heating temperature is preferably 150 ° C. or lower, more preferably 135 ° C. or lower, still more preferably 130 ° C. or lower. The heating time is preferably 5 minutes or longer, more preferably 15 minutes or longer, and even more preferably 25 minutes or longer. If the heating time is less than 5 minutes, the conductive thin film is not sufficiently cured and the adhesion is insufficient.

The base material to which the conductive paste is applied is not particularly limited, and examples thereof include polycarbonate, acrylic, polyimide, and polyester. Further, a conductive laminated body can be obtained by providing a transparent conductive layer between the base material and the conductive film and laminating the conductive thin film on the transparent conductive layer. The material of the transparent conductive layer is not particularly limited, and for example, an ITO film containing indium tin oxide as a main component or a nanowire-based conductive thin film can be applied. Further, as the transparent conductive layer, not only the one formed on the entire surface of the base material but also the one in which a part of the transparent conductive layer is removed by etching can be used.

A touch panel can be manufactured using the conductive laminate of the present invention. The touch panel may be of a resistive film type or a capacitance type. Although it can be applied to any touch panel, this paste is suitable for forming fine lines, and therefore is preferably used in the capacitance method.

The method for manufacturing the touch panel is not particularly limited, but is conductive so as to form a circuit that imparts conductivity after curing on a substrate on which a transparent conductive layer such as an ITO film is laminated. It can be manufactured by applying or printing a paste, curing the conductive paste applied or printed by heating to form a conductive laminate, and laminating the obtained conductive laminate with another conductive laminate. it can.

The conductive paste of the present invention is suitably used for electrode circuit wiring of touch panels, but also for electromagnetic wave shielding applications, circuit formation applications for electronic components, conductive adhesives for terminals and lead wires, and the like. Can also be used. Further, it can be suitably used for printing a material attracting attention as a substitute for a transparent conductive film such as ITO film or ITO glass having a mesh-like pattern.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following embodiments. Unless otherwise specified, "parts" in the example indicates "parts by mass", and the solid content concentration indicates the non-volatile content after the organic solvent is completely volatilized.

The evaluation of the physical properties of the polyester resin and the polyurethane resin in the present invention and the evaluation of the conductive paste were carried out by the following methods.

1. 1. Number average molecular weight The sample resin was dissolved or diluted in tetrahydrofuran so that the resin concentration was about 0.5% by weight, and filtered through a polytetrafluoride ethylene membrane filter having a pore size of 0.5 μm to prepare a GPC measurement sample. Using tetrahydrofuran as the mobile phase, using a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation, and using a differential refractometer (RI meter) as a detector, the resin sample was prepared at a column temperature of 30 ° C. and a flow rate of 1 ml / min. GPC measurement was performed. Using the GPC measurement results of monodisperse polystyrene having a known number average molecular weight, the polystyrene-equivalent number average molecular weight of the sample resin was determined, and these were used as the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the sample resin. However, as the column, shodex KF-802, 804L, 806L manufactured by Showa Denko KK was used.

2. Glass transition temperature (Tg)
5 mg of the sample resin is placed in an aluminum sample pan, sealed, and measured using a differential scanning calorimetry (DSC) DSC-220 manufactured by Seiko Instruments Co., Ltd. at a temperature rise rate of 20 ° C./min up to 200 ° C. Then, it was determined by the temperature of the intersection of the extension line of the baseline below the glass transition temperature and the tangent line showing the maximum inclination at the transition part.

3. 3. Acid value 0.2 g of the sample was precisely weighed and dissolved in 20 ml of chloroform. Then, it was determined by titration with 0.01 N potassium hydroxide (ethanol solution). A phenolphthalein solution was used as an indicator. The unit of acid value was eq / ton, that is, equivalent per ton of sample.

5. Fabrication of Conductive Laminated Test Piece PET film with 100 μm thickness annealed (Cosmo Shine A manufactured by Toyobo Co., Ltd.)
A conductive paste is printed on the 4300) or ITO film (KH150 manufactured by Oike Kogyo Co., Ltd.) by a screen printing method to form a solid coating pattern having a width of 30 mm and a length of 50 mm, and dried at 130 ° C. for 30 minutes. The cured product was used as a conductive laminate test piece. The coating thickness at the time of printing was adjusted so that the dry film thickness was 8 to 12 μm.

6. Adhesion Using a conductive laminate test piece, evaluation was performed by a peeling test using cellophane tape (registered trademark) (manufactured by Nichiban Co., Ltd.) in accordance with JIS K-5400-5-6: 1990. A cross cut of a total of 100 squares of 10 squares × 10 squares was formed at 1 mm intervals, and cellophane tape peeling was performed. The degree of peeling of the coating film on the ITO film was visually evaluated. The evaluation criteria are as follows.
○: Items that do not come off at all.
Δ: Partially peeled off.
X: Those with 50% or more peeling.

7. Specific resistance The sheet resistance and film thickness of the conductive laminate test piece were measured, and the specific resistance was calculated. For the film thickness, a thickness gauge SMD-565L (manufactured by TECLOCK Co., Ltd.) was used, the thickness of the cured coating film was measured at 3 points with the thickness of the PET film as the zero point, and the average value was used. The sheet resistance was measured for four test pieces using Loresta-GP MCP-T610 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the average value was used.

8. Pencil hardness A conductive laminate test piece was placed on a SUS304 plate having a thickness of 2 mm, and the pencil hardness was measured according to JIS K 5600-5-4: 1999.

9. Adhesion evaluation after high-temperature and high-humidity treatment The conductive laminate test piece was placed in a high-temperature and high-humidity tank at 85 ° C.-85% RH, treated for 120 hr, and then the obtained test piece was subjected to 10 squares at 1 mm intervals. A cross cut of 10 squares in total of 100 squares was formed, and cellophane tape peeling was performed. Then, the degree of peeling of the coating film on the ITO film was visually evaluated. The evaluation criteria are as follows.
○: Items that do not come off at all.
Δ: Partially peeled off.
X: Those with 50% or more peeling.

10. Evaluation of fine line printability A nickel electroformed flat intaglio plate with multiple concave patterns with a line width of 30 μm, a depth of 20 μm, and a pitch of 60 μm is used as the printing plate used for gravure offset printing, and PET film (Cosmo manufactured by Toyobo Co., Ltd.) is used as the base material to be printed. Shine A4300) was prepared respectively. Moreover, a silicone blanket having a thickness of 0.6 mm was used as a blanket for printing. First, a predetermined amount of the conductive paste was supplied to the surface of the flat intaglio, and the conductive paste was embedded in the concave pattern of the flat intaglio using a metal squeegee. Next, the silicone blanket was rotated in a state of being pressed against the flat intaglio and slid on the flat intaglio, so that the conductive paste embedded in the concave pattern of the flat intaglio was received on the surface of the silicone blanket. Finally, the silicone blanket was rotated in a state of being pressed against the PET film and slid on the PET film to obtain a printed matter having a predetermined pattern on the surface of the PET film. Using the above printed matter, L / S was measured with a digital microscope VHX-2000 (manufactured by KEYENCE CORPORATION), and the state of fine lines was observed to evaluate the fine line printability according to the following criteria.
◯: There is no disconnection and there is no short circuit between thin wires.
X: There is a partial disconnection or a short circuit between thin wires.

11. Preparation of Conductive Paste Each component is blended at the blending ratio (mass ratio) shown in Tables 1 and 2 and kneaded with a three-roll mill to obtain the conductive pastes of Examples 1 to 7 and Comparative Examples 1 to 3. It was.

Polyester 1: RV630 manufactured by Toyobo Co., Ltd. (number average molecular weight 23,000, acid value 20 eq / ton, glass transition temperature 7 ° C)
Polyester 2: GK390 manufactured by Toyobo Co., Ltd. (number average molecular weight 18,000, acid value 80 eq / ton, glass transition temperature 7 ° C)
Polyester 3: RV296 manufactured by Toyobo Co., Ltd. (number average molecular weight 14,000, acid value 80 eq / ton, glass transition temperature 71 ° C)
Polyurethane 4: UR-PS9 manufactured by Toyobo Co., Ltd. (number average molecular weight 22,000, acid value 170 eq / ton, glass transition temperature 100 ° C)
Polyester polyol 1: Kuraray Co., Ltd. P-2013 (number average molecular weight 2,000, acid value 3eq / ton, hydroxyl value 54.4KOHmg / g)
Polyester polyol 2: P-2030 manufactured by Kuraray Co., Ltd. (number average molecular weight 2,000, acid value 4eq / ton, hydroxyl value 55.4KOHmg / g)
Polyester polyol 3: manufactured by Kuraray Co., Ltd. P-1030 (number average molecular weight 1,000, acid value 3eq / ton, hydroxyl value 111.3KOHmg / g)
Polyester polyol 4: Kuraray Co., Ltd. F-3010 (number average molecular weight 3,000, acid value 5eq / ton, hydroxyl value 55.8KOHmg / g)
Blocked isocyanate 1: Trixene BI 7982 manufactured by Baxenden (solid content 70% by weight, theoretical isocyanate value 10.2% by weight)
Blocked isocyanate 2: Trixene BI 7992 manufactured by Baxenden (solid content 70% by weight, theoretical isocyanate value 9.2% by weight)
Blocked isocyanate 3: Trixene BI 7950 manufactured by Baxenden (solid content 65% by weight, theoretical isocyanate value 7.4% by weight)
Silver powder 1: Fukuda Metal Leaf Powder Industry Co., Ltd. AgC-251 (D50 = 1.8 μm, flaky silver powder)
Silver powder 2: Ferro Japan SF30 Co., Ltd. (D50 = 1.0 μm, flake-shaped silver powder) Silver powder 3: DOWA Hightech Co., Ltd. G-35 (D50 = 6.1 μm, aggregated silver powder)
Silver powder 4: DOWA Hightech Co., Ltd. AG2-1C (D50 = 1.1 μm, spherical silver powder)
Organic solvent 1: Diethylene glycol monoethyl ether acetate (boiling point 217 ° C)
Organic solvent 2: Diethylene glycol monobutyl ether acetate (boiling point 247 ° C)
Organic solvent 3: Tetraethylene glycol dimethyl ether (boiling point 276 ° C)
Organic solvent 4: Triethylene glycol monobutyl ether (boiling point 278 ° C)
Organic solvent 5: Triethylene glycol diacetate (boiling point 300 ° C)
Dispersant 1: Disperbyk2155 manufactured by Big Chemie Japan Co., Ltd.
Leveling agent 1: Kyoeisha Chemical Co., Ltd. MK Conch

12. Evaluation Results Tables 3 and 4 show the results of various evaluations of the conductive pastes of Examples 1 to 7 and Comparative Examples 1 to 3. As shown in Tables 3 and 4, it can be seen that the conductive pastes of Examples 1 to 7 can achieve both good printability and ITO adhesion.

The conductive paste of the present invention can be used in the manufacture of printed wiring and the like used in various electronic devices. It can also be used for electromagnetic wave shielding applications, circuit forming applications for electronic components, conductive adhesives for terminals and lead wires, and the like.

Claims (11)

A conductive paste containing at least a thermoplastic resin (A), a thermoplastic resin (B), a curing agent (C), a conductive powder (D), and an organic solvent (E), and the thermoplastic resin (A) is hot. A polyurethane resin and / or a thermoplastic resin (B) having a weight ratio of 4.0 times or less with respect to the plastic resin (B), a thermoplastic resin (A) having a weight average molecular weight of 10,000 or more and a glass transition temperature of -10 to 150 ° C. It is a polyester resin, and the thermoplastic resin (B) is an amorphous polyol, has a number average molecular weight of 500 to 6,000, and has an acid value of 20 to 500 eq of a non-volatile organic component in a heat treatment at 130 ° C. for 30 minutes. / ton der is, a conductive paste characterized by having the following fine line printability 50 [mu] m. The conductive paste according to claim 1, wherein the conductive powder (D) has an average particle diameter (D50) of at least 7 μm or less. The conductive paste according to any one of claims 1 and 2, wherein the thermoplastic resin (B) is a polyester polyol and / or a polyether polyol, and / or a polycarbonate polyol. The curing agent (C) is an isocyanate compound, and the mixing amount of the curing agent (C) with respect to the thermoplastic resin (B) is the same as that of the curing agent (C) with respect to the hydroxyl group of the thermoplastic resin (B). The conductive paste according to any one of claims 1 to 3, wherein the isocyanate group is 20 to 200 mol%. The conductive paste according to any one of claims 1 to 4, wherein the organic solvent (E) has a boiling point of 100 ° C. or higher, and the weight fraction with respect to the total weight of the conductive paste is 25% by weight or less. The conductive paste according to any one of claims 1 to 5, wherein the conductive powder (D) is mainly composed of silver. Gravure offset printing (The conductive paste is filled in a printing plate having a concave pattern, and the filled conductive paste is received by a printing blanket having a silicone rubber sheet on the surface, and then from the printing blanket onto the substrate to be printed. The conductive paste according to any one of claims 1 to 6, wherein the conductive paste is used for printing and forming an electrode pattern). The conductive pace according to any one of claims 1 to 6 is gravure-offset printed (the conductive paste is filled in a printing plate having a concave pattern, and the filled conductive paste is printed with a silicone rubber sheet on the surface). After acceptance into the blanket for printing, the conductive coating film obtained (from the method of transferring the conductive paste from the blanket for printing onto the substrate to be printed and printing and forming the electrode pattern) is dried and / or cured. The printed matter obtained. The printed matter according to claim 8, wherein the line / space pitch is 100 μm or less. A conductive laminate obtained by laminating the printed matter according to any one of claims 8 to 9 on a transparent conductive layer. A touch panel using the conductive laminate according to claim 10.