WO2015046096A1

WO2015046096A1 - Electro-conductive paste, electro-conductive film, electro-conductive circuit, electro-conductive laminate, and touch panel

Info

Publication number: WO2015046096A1
Application number: PCT/JP2014/074994
Authority: WO
Inventors: 康博坂本; 渉川島; 万紀木南
Original assignee: 東洋紡株式会社
Priority date: 2013-09-30
Filing date: 2014-09-22
Publication date: 2015-04-02
Also published as: CN105612585B; JPWO2015046096A1; CN105612585A; JP6767089B2; TW201517060A; TWI648748B

Abstract

　The electro-conductive paste has fine-line printability of 50μm or less, outstanding adhesion to an ITO film in an electro-conductive pattern formed by a low-temperature process at a temperature not exceeding 150°C, and achieves environmental reliability and high durability. The electro-conductive paste contains at least: a thermoplastic resin (A) and a thermoplastic resin (B), a hardener (C), an electro-conductive powder (D) and an organic solvent (E). The weight ratio of thermoplastic resin (A) to thermoplastic resin (B) does not exceed 4.0:1, and thermoplastic resin (A) is a polyurethane resin or a polyester resin having a weight-average molecular weight of at least 10,000 and a glass transition temperature of -10 to 150°C. Thermoplastic resin (B) is a polyester polyol and/or polyether polyol, having a number average molecular weight of 500 to 6,000.

Description

Conductive paste, conductive coating film, conductive circuit, conductive laminate, and touch panel

The present invention relates to a conductive paste and use thereof, and more specifically, a conductive paste excellent in fine line printability, a conductive circuit using the same, a conductive coating film, and the conductive coating film is a transparent conductive layer. The present invention relates to a conductive laminate laminated on top and a touch panel using the conductive laminate.

Transparent touch panels that operate by touching the screen with a finger or a dedicated pen are widely used, including ATMs, car navigation systems, game machines, station ticket vending machines, photocopiers, museum commentary terminals, and convenience store information terminals. It is used for applications and is spreading. The transparent touch panel is configured to form a switch by superposing 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 vapor deposition or sputtering, and the ITO film is etched. In general, it is formed by patterning.

There are various types of touch panels, and a resistive film type and a capacitance type are representative types. In recent years, the electrostatic capacity method, which has been attracting attention with the spread of smartphones and tablet PCs, identifies the touched position on the panel by sensing a discharge phenomenon that occurs when the panel is touched with a finger or a dedicated pen. It is a feature of the resistive film system that multipoint sensing is possible. In order to perform multipoint sensing with high resolution, it is necessary to form a larger number of electrode circuit wirings than in the conventional resistive film method. Furthermore, in recent years, in order to make the display screen larger and due to demands on product design, there is an increasing demand for a narrower frame portion on which the electrode circuit wiring is arranged. From such a background, it is required to form a large number of wiring electrodes at a high density, and the demand for high-definition electrode circuit wiring is becoming stronger.

In order to form a large number of electrode circuit wirings at a high density, thin wirings may be arranged at short intervals. As a construction method therefor, a photolithography method can be cited, but the environmental burden due to waste liquid treatment is large, the process is complicated, and there are many problems including a cost viewpoint. In addition, since the conductive circuit formed by the photolithography method is formed only of a metal such as aluminum or copper, there is a problem that it is weak against physical impact such as bending. In addition, the mainstream of the base material used in the photolithography method from the environment in which it is used is glass, but today there is a demerit that the selectivity of the base material is limited because the weight reduction of the touch panel is required.
On the other hand, the printing method is excellent in substrate selectivity. For example, 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 a thin line can be formed by using a conductive paste by the printing method, there will be an extremely merit. In addition, since the conductive paste uses a binder resin as a binder with the base material, there is a merit for physical impact such as bending. However, in order to form a thin conductive pattern using a conductive paste in the printing method, the fine line suitability of the conductive paste is required.

As for the line width required for the electrode circuit wiring of the resistance film system, the width of the line and the space (hereinafter abbreviated as L / S) is often 200 μm (200/200 μm) or more, and the conductive pattern is relatively rough. It was enough if it could be formed, but due to the widespread use of capacitive touch panels, the recent requirement for L / S is 100/100 μm or less, and further L / S may be required to be 50/50 μm or less. The demand for fine wire suitability is increasing.

Therefore, various researches have been made on conductive pattern formation methods that are low in cost and do not generate harmful waste liquids. In particular, the conductive paste is filled in a printing plate having a concave pattern, and the filled conductive paste is received into a printing blanket having a silicone rubber sheet on the surface, and then from the printing blanket onto the substrate to be printed. Gravure offset printing, which is a method of printing and forming electrode patterns by transferring conductive paste, has attracted attention as an alternative to photolithography because it can form fine conductive patterns with high accuracy. ing.

As a method of forming a conductive pattern using a gravure offset printing method, a method of manufacturing a coating film by transferring a conductive ink to a transfer target composed of a glass substrate is conventionally known (see, for example, Patent Document 1). . However, this conventional technology uses a designed conductive ink in consideration of application to a glass substrate that can be sintered at a high temperature, and is suitable for a touch panel using an ITO film provided on a PET film or the like. There was a problem that it was difficult.

As described above, it is possible to form fine lines with high precision 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 of the processing process and the heat resistance of the film substrate. It is required to develop the physical properties of the coating film with a lower heat treatment of 150 ° C. or lower. Furthermore, with the recent downsizing and generalization of touch panels, the environment used and the frequency of use have become more versatile than before, so the environmental reliability and durability of the required formed electrodes are higher. Things are needed.

Japanese Patent No. 5088063

The present invention has been made against the background of such prior art problems. That is, the object of the present invention is to have fine line printability of 50 μm or less and 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. An object is to provide a conductive paste that can be realized.

As a result of intensive studies to achieve the above object, the present inventor has made fine line printing in gravure offset printing by including two or more kinds of thermoplastic binder resins having different number average molecular weights and a curing agent in the conductive paste. The conductive pattern formed by a low-temperature process of 150 ° C. or less has excellent adhesion to the ITO film, and further has obtained knowledge that environmental reliability and high durability can be maintained.

That is, the present invention has the following configuration.
(1) A conductive paste containing at least a thermoplastic resin (A) and a thermoplastic resin (B), a curing agent (C), a conductive powder (D), and an organic solvent (E), wherein the thermoplastic resin (A ) Is a polyurethane resin having a weight ratio of 4.0 times or less with respect to the thermoplastic resin (B), the thermoplastic resin (A) having a weight average molecular weight of 10,000 or more and a glass transition temperature of −10 to 150 ° C. And / or a polyester resin, wherein 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 conductive powder (D) has an average particle size (D50) of at least 7 μm or less.
(3) The conductive paste according to (1) or (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 nonvolatile organic component in a 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 a curing agent (with respect to 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) The organic solvent (E) has a boiling point of 100 ° C. or higher and a weight fraction based on the total weight of the conductive paste is 25% by weight or less, according to any one of (1) to (5) 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 its 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 printing an electrode pattern by transferring a conductive paste onto a substrate.
(9) Gravure offset printing of the conductive pace according to any one of (1) to (7) above (filling a conductive paste with a printing plate having a concave pattern and applying the filled conductive paste on the surface After receiving the printing blanket having a silicone rubber sheet, the conductive coating is obtained by transferring the conductive paste from the printing blanket onto the substrate to be printed and printing and forming the electrode pattern. And / or printed matter obtained by curing.
(1O) The printed matter according to (9), wherein the line / space pitch is 100 μm or less.
(11) A conductive laminate in which the printed matter according to (9) to (10) is laminated on a transparent conductive layer. (12) A touch panel using the conductive laminate according to (11).

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, so that the conductive paste is formed by a fine line gravure offset printability and a low temperature process of 150 ° C. or lower. The pattern has excellent adhesion to the ITO film, and has both environmental reliability and high durability.

Hereinafter, the conductive paste of the embodiment of the present invention will be described.
The conductive paste of this embodiment is a conductive paste containing at least the thermoplastic resin (A) and the thermoplastic resin (B), the curing agent (C), the conductive powder (D), and the organic solvent (E). The weight ratio of the thermoplastic resin (A) to the thermoplastic resin (B) is 4.0 times or less, the thermoplastic resin (A) has a weight average molecular weight of 10,000 or more and a glass transition temperature of −10 to 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) is in a weight ratio with respect to the thermoplastic resin (B). Is 4.0 times or less. When two types of thermoplastic resins having different number average molecular weights are used as the binder resin, the molecular weight distribution curve in GPC analysis often has a peak of more than two mountains. This is because the peak tops of the molecular weight distribution of each thermoplastic resin are different, and as a result, the molecular weight distribution becomes broader than when a single resin is used. That is, compared with a single resin, the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of the whole binder resin is increased. This is environmental stability, high durability and printability. Contributes to realizing both.

It should be noted that the conductive paste of the present invention may contain three or more types of resins as long as environmental stability, durability and printability are not impaired.

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 in the application of the conductive paste or curing after printing, and the conductive powder such as metal powder inside the coating film can be secured between each other. High conductivity can be expressed by the closer distance.

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, and further preferably 50 mol% or more. If the aromatic dicarboxylic acid is less than 20% by weight, the strength of the coating film is lowered, and durability such as low-temperature flex resistance, heat resistance, moisture resistance, and thermal shock resistance may be lowered. The upper limit with preferable 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, terephthalic acid and isophthalic acid are preferably used in combination in view of physical properties and solvent solubility.

Other dicarboxylic acids copolymerized with the polyester include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, azelaic acid, dibasic acids having 12 to 28 carbon atoms, 1 , 4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, Dicarboxy hydrogenated 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 Acid But, sebacic acid from the viewpoint of moisture resistance, adipic acid, azelaic acid, 1,4-cyclohexane dimethanol are preferred.

Further, within the scope of not impairing the contents of the invention, polycarboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid, and sulfonic acids such as sodium 5-sulfoisophthalate. A metal base-containing dicarboxylic acid may be used in combination. Further, after polymerization of the polyester resin, an acid anhydride such as trimellitic anhydride or phthalic anhydride may be post-added to give 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, , 5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, etc. Alkylene glycol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol , Tricyclodecane glycol, alicyclic glycols such as dimer diol, diethylene glycol, polyethylene glycol, and polyether diols such as polytetramethylene glycol. Further, an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of bisphenol F, or a polyvalent polyol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, or polyglycerin may be used in combination.

The polyester resin preferably has no melting point (indicating that it is amorphous) from the viewpoint of adhesiveness, flexibility, solvent solubility, and the like. The term “having no melting point” as used herein means that no clear melting peak is exhibited 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 the polyurethane resin can be polymerized in a solution, it has a feature that it can easily obtain a higher molecular weight than the polyester resin. Preferable examples of the amorphous polyol include (meth) acrylic polyol, polycarbonate diol, polybutadiene polyol, polyester polyol and polyether polyol. Polycarbonate diol, polyether polyol, and polyester polyol are more preferable from the viewpoint of adhesiveness, flex resistance, and durability, and polyester polyol is more preferable from the viewpoint of freedom of molecular design.

When the amorphous polyol used when the thermoplastic resin (A) is a polyurethane resin, the preferred component is the same as that of the polyester resin, 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 preferably has a hydroxyl group and an amino group, and may have either one or both. Specific examples of components include dimethylolbutanoic acid and dimethylolpropionic acid, 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-dimethyl-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-pentane In one molecule such as all, 3-phenyl-1,5-pentanediol, 2,5-dimethyl-3-sodium sulfo-2,5-hexanediol, dimer diol (eg, PRIPOOL-2033 manufactured by Unikema International) A compound having two hydroxyl groups, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, polyglycerin and other polyhydric alcohols, monoethanolamine, diethanolamine, triethanolamine and one molecule with one or more hydroxyl groups Amino alcohol having an amino group, ethylenediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, etc. Aliphatic Jami And compounds having two amino groups in one molecule such as aromatic diamines such as metaxylenediamine, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenyl ether, and 4,4′-diaminodiphenyl ether. . These compounds may be used alone or in combination, and there is no problem.

The polyisocyanate compound used when synthesizing the polyurethane resin is not particularly limited, but aromatic, aliphatic, alicyclic diisocyanate and the like are preferable. For example, 2,4-tolylene diisocyanate, 2,6-tolylene 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′-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, m-xylene Examples include diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate.

The number average molecular weight (Mn (A)) of the thermoplastic resin (A) is 10,000 to 70,000, more preferably 10,000 to 40,000, and still more preferably 10,000 to 30,000. It 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 increases and the durability and the like are improved, but the fine line printability in gravure offset printing is significantly reduced.

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 a high temperature, which may reduce the reliability of the conductive thin film formed from the paste. Alternatively, the paste-containing component may move to the contact partner side during use, and the reliability of the conductive thin film may be reduced. 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 preferably 100 ° C. or lower in consideration of printability, adhesion, solubility, paste viscosity, printability, and the like. Further preferred.

In the present invention, it is preferable that the solid organic component of the conductive paste contains a carboxyl group, and the amount (acid value) of the carboxyl group is within a predetermined range. As a preferred embodiment, the thermoplastic resin (A) preferably has an acid value within 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, and 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 substrate tends to be low. On the other hand, if the acid value of the thermoplastic resin (A) is too high, the water-absorbing property of the formed conductive thin film increases, and the hydrolysis of the thermoplastic resin may be accelerated by the catalytic action of the carboxyl group. There is a tendency that the reliability of the conductive thin film is lowered.

Also, it is 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. The diol compound having a carboxy group is preferably added so that the acid value of the nonvolatile organic component in a heat treatment at 130 ° C. for 30 minutes is 20 to 500 eq / ton, more preferably 30 to 350 eq / ton. .

The kind of the thermoplastic resin (B) is not particularly limited, but 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 because of the degree of freedom in molecular design. By blending the thermoplastic resin (B) having a number average molecular weight lower than that of the thermoplastic resin (A), the transferability of the conductive paste from the silicone blanket to the film when performing gravure offset printing can be improved. Fine line printability is significantly improved.

As a preferable dicarboxylic acid component in the case of using a polyester polyol as the thermoplastic resin (B), terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, Aliphatic dicarboxylic acids such as dodecane dicarboxylic acid and azelaic acid, dibasic acids having 12 to 28 carbon atoms, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl Hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalene dicarboxylic Acid Alicyclic dicarboxylic acids such as tricyclodecane acid, hydroxybenzoic acid, hydroxycarboxylic acids such as lactic acid. These may be used alone or in combination of two or more. Of these, terephthalic acid and isophthalic acid are preferably used in combination in view of physical properties and solvent solubility.

Further, within the scope of not impairing the contents of the invention, polycarboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid, and sulfonic acids such as sodium 5-sulfoisophthalate. A metal base-containing dicarboxylic acid may be used in combination. Further, after polymerization of the polyester polyol, an acid anhydride such as trimellitic anhydride or phthalic anhydride may be post-added to give an acid value.

Furthermore, the following well-known glycol can be used for the glycol component in the case of using polyester polyol. 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, , 5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, etc. Alkylene glycol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol , Tricyclodecane glycol, alicyclic glycols such as dimer diol, diethylene glycol, polyethylene glycol, and polyether diols such as polytetramethylene glycol. Further, an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of bisphenol F, or a polyvalent polyol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, or polyglycerin may be used in combination. Further examples include polycaprolactone polyols obtained by ring-opening polymerization using ε-caprolactone as a polyhydric alcohol.
These may be used alone or in combination of two or more.

When the thermoplastic resin (B) is a polyether polyol, for example, a polymer obtained by adding an alkylene oxide, such as ethylene oxide or propylene oxide, alone or a mixture to a polyhydric alcohol, such as glycerin or propylene glycol, alone or in a mixture. Ether polyols, polytetramethylene glycols, polyether polyols obtained by reacting alkylene oxide with polyfunctional compounds such as ethylenediamine and ethanolamine, and obtained by polymerizing acrylamide etc. using these polyethers as a medium And so-called polymer polyols.

When the thermoplastic resin (B) is a polycarbonate polyol, a polycarbonate diol containing one or two or more linear aliphatic diol-derived repeating units as a constituent unit, one or two or more alicyclic diols Examples thereof include polycarbonate diol containing a repeating unit derived from a structural unit, or polycarbonate diol containing a repeating unit derived from both of these diols as a structural unit. Specific examples of constituents include 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol as linear aliphatic diols. Examples of the alicyclic diol include 1,4-cyclohexanedimethanol.

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 is lowered, and the suitability for fine line printing is 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 fine line printability in gravure offset printing is significantly reduced. The thermoplastic resin (B) may have an acid value within a predetermined range in order to improve 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 fine line printability 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, polystyrene, polyamide resins, There is no restriction on the combined use of polyamideimide resin, polycarbonate resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, polyvinyl butyral resin, cellulose and modified celluloses.

The kind of the curing agent (C) that can react with the binder resin of the present invention is not particularly limited, but an isocyanate compound is particularly preferable from the viewpoint of adhesion, flex resistance, curability, and the like. Furthermore, it is preferable to use those having an isocyanate group blocked as these isocyanate compounds because the storage stability is improved. Examples of curing agents other than isocyanate compounds include known compounds such as amino resins such as methylated melamine, butylated melamine, benzoguanamine, and urea resin, acid anhydrides, imidazoles, epoxy resins, and phenol resins. These curing agents can be used in combination with a known catalyst or accelerator selected according to the type. The blending ratio of the thermoplastic resin (B) and the curing agent (C) is such that the functional group capable of reacting with the hydroxyl group of the curing agent (C) is 20 to 200 mol% 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 isocyanate compounds that can be blended in the conductive paste of the present invention include aromatic or aliphatic diisocyanates, trivalent or higher polyisocyanates, and any of low molecular compounds and high molecular compounds may be used. For example, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate, etc. Alicyclic diisocyanates, or trimers of these isocyanate compounds, and excess amounts of these isocyanate compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine Low molecular active hydrogen compounds such as Polyester polyols, polyether polyols, terminal isocyanate group-containing compounds obtained by reacting a polymeric active hydrogen compound such as polyamides and the like. Examples of the blocking agent for isocyanate groups include phenols such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, chlorophenol, and oximes such as acetoxime, methylethyl ketoxime, and cyclohexanone oxime. Alcohols such as methanol, ethanol, propanol and butanol, halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, and tertiary alcohols such as t-butanol and t-pentanol. , Ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propylolactam and other lactams, and 3,5-dimethylpyrazole and other pyrazoles. Aromatic amines, imides, acetylacetone, acetoacetic ester, active methylene compounds such as malonic acid ethyl ester, mercaptans, imines, imidazoles, ureas, diaryl compounds, sodium bisulfite, etc. can be mentioned. 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 for imparting conductivity in the formed conductive pattern.
The conductive powder (D) in the present invention is preferably noble metal powder such as silver powder, gold powder, platinum powder and palladium powder, and base metal powder such as copper powder, nickel powder, aluminum powder and brass powder. Further, a plating powder obtained by plating different kinds of particles made of an inorganic material such as a base metal or silica with a noble metal such as silver, a base metal powder obtained by alloying with a noble metal such as silver, or the like can be given. Moreover, you may use the electroconductive powder which consists of nonmetals, such as carbon-type fillers, such as carbon black and graphite powder, as electroconductive powder (D) in this invention. When carbon black and graphite powder are included, the carbon black and / or graphite powder content may 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, silver powder alone or those mainly composed of silver powder is particularly preferable in that it is easy to obtain a coating film exhibiting high conductivity.

The shape of the conductive powder (D) is not particularly limited, but examples of preferable shapes are described in the known flake shape (flaky shape), spherical shape, dendritic shape (dendritic shape), and JP-A-9-306240. As shown, the shape (aggregated powder) in which the primary particles are aggregated three-dimensionally can be exemplified. Among these, flaky, spherical, and agglomerated powders are preferable, and they may be used alone or in combination.

The particle diameter of the conductive powder (D) is not particularly limited, but from the viewpoint of imparting fine wire suitability, a powder having a center diameter (D50) of 7 μm or less is preferable. When the 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, causing 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, from the viewpoint of obtaining an excellent conductive circuit. More preferably, it is × 10 ⁻⁴ or less.

The following inorganic substances can be added to the conductive paste of the present invention. Examples of inorganic substances include silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, diamond carbon lactam, and other carbides; 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 titanate compounds such as calcium titanate, magnesium titanate, strontium titanate; sulfides such as molybdenum disulfide; various fluorides such as magnesium fluoride and carbon fluoride; aluminum stearate, calcium stearate Um, zinc stearate, various metal soaps such as magnesium stearate and the like; may be used talc, bentonite, talc, calcium carbonate, bentonite, kaolin, glass fiber, mica or the like. By adding these inorganic substances, it may be possible to improve printability and heat resistance, as well as mechanical properties and long-term durability. Among these, in the conductive paste of the present invention, silica is preferable from the viewpoint of imparting printability. That is, when silica is present, the viscosity can be increased by physical cohesion between fillers containing silica and by pseudo-crosslinking by hydrogen bond formation. The silica to be used can be used regardless of its particle diameter, its hydrophilicity or 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. Furthermore, carbodiimide, epoxy, or the like can be appropriately used as a resin degradation inhibitor. These can be used alone or in combination.

As the organic solvent (E) in the present invention, the boiling point at 0.1013 MPa is preferably 100 ° C. or higher and lower than 350 ° C., 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, the solvent volatilizes during the paste manufacturing process or use of the paste, and there is a concern that the component ratio of the conductive paste is likely to change. On the other hand, if the boiling point of the organic solvent is too high, when a low-temperature drying step is required (for example, 150 ° C. or less), a large amount of the solvent may remain in the coating film, causing 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 well dispersed. Those are preferred. For example, cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, Exson Chemical's Solvesso 100, 150, 200, propylene glycol monomethyl ether acetate, terpionol, 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 monobutyl ether Examples include acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, benzyl butyrate, benzyl benzoate, and the like. In addition, examples of petroleum-based hydrocarbons include AF Solvent No. 4, No. 5, No. 6, No. 7, and No. 0 Solvent H manufactured by Nippon Oil Corporation. The above may be included.
Such an organic solvent is appropriately contained so that the conductive paste has a viscosity suitable for printing or 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 with respect to 100 parts by weight of the total paste. If the content of the organic solvent (E) is too high, the paste viscosity becomes low and sagging occurs during fine line printing.

When such a conductive paste is used for gravure offset printing, in order to obtain good printability, its concentration is a commercially available cone plate viscometer (for example, RE-85 manufactured by Toki Sangyo Co., Ltd.). The measured value (measured value after 180 seconds at the start of rotation at 25 ° C., rotation speed 2.5 rpm) with a 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 reduced, and the printed matter is good. It becomes 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 a doctor blade is deteriorated, and background stains (adhesion of paste to non-image areas) are likely to occur. Further, the amount of conductive paste received from the printing plate to the printing blanket is reduced, and disconnection and stringing occur in the electrode pattern. More preferably, it is 20 to 300 dPa · s. In addition, it is also possible to dilute appropriately 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 the filler mass part with respect to 100 mass parts of the total solid content contained in the paste, and is represented by F value = (filler mass part / solid mass part) × 100. The filler mass part referred to here is the mass part of the conductive powder (D), the solid content mass part is the mass part of the components other than the solvent, and the conductive powder, binder resin, 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 further the printability 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. .

The step of evaporating the organic solvent (E) is carried out under heating, whereby 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 underlying transparent conductive layer and energy saving in the production process, the heating temperature is preferably 150 ° C. or lower, more preferably 135 ° C. or lower, and further 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. When 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. Moreover, a conductive laminated body can be obtained by providing a transparent conductive layer between the said base material and a conductive film, and laminating | stacking a conductive thin film on a transparent conductive layer. The material of the transparent conductive layer is not particularly limited. For example, an ITO film mainly composed of indium tin oxide or a nanowire-based conductive thin film can be applied. Further, the transparent conductive layer is not limited to the one formed on the entire surface of the base material, but a layer obtained by removing a part of the transparent conductive layer by etching can also be used.

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

The touch panel manufacturing method is not particularly limited. For example, a conductive film is formed on a base material 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, forming a conductive laminate, and bonding the resulting conductive laminate to another conductive laminate. it can.

The conductive paste of the present invention is preferably used for electrode circuit wiring of touch panels, but besides that, it is used for electromagnetic shielding applications, electronic component circuit formation applications, conductive adhesives for terminals and lead wires, etc. Can also be used. Furthermore, it can also be suitably used for printing a material that is attracting attention as an alternative to a transparent conductive film such as an ITO film or ITO glass having a mesh pattern.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, this invention is not limited to the following embodiment. Unless otherwise specified, “parts” in the examples indicates “parts by mass”, and the solid content concentration indicates a non-volatile content after the organic solvent is completely volatilized.

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

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 polytetrafluoroethylene membrane filter having a pore size of 0.5 μm to obtain a GPC measurement sample. Tetrahydrofuran was used as a mobile phase, a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation was used, a differential refractometer (RI meter) was used as a detector, a column temperature of 30 ° C., and a flow rate of 1 ml / min. GPC measurement was performed. The number-average molecular weight in terms of polystyrene of the sample resin was determined using the GPC measurement result of monodisperse polystyrene having a known number-average molecular weight, which was used as the number-average molecular weight (Mn) and the weight-average molecular weight (Mw) of the sample resin. However, shodex KF-802, 804L, 806L manufactured by Showa Denko KK was used as the column.

2. Glass transition temperature (Tg)
5 mg of sample resin is put in an aluminum sample pan, sealed, and measured with a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Inc. up to 200 ° C. at a heating rate of 20 ° C./min. And the temperature at the intersection of the base line extension below the glass transition temperature and the tangent indicating the maximum slope at the transition.

3. Acid value 0.2 g of a sample was precisely weighed and dissolved in 20 ml of chloroform. Subsequently, it titrated with 0.01N potassium hydroxide (ethanol solution). A phenolphthalein solution was used as an indicator. The unit of the acid value was eq / ton, that is, the equivalent per 1 ton of the sample.

5. Preparation of conductive laminate test piece PET film annealed to a thickness of 100 μm (Cosmo Shine A manufactured by Toyobo Co., Ltd.)
4300) or ITO film (Oike Industry Co., Ltd., KH150), a conductive paste is printed by a screen printing method to form a solid coating pattern with 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). Adhesiveness Using a conductive laminate test piece, according to JIS K-5400-5-6: 1990, evaluation was performed by a peel test using Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd.). A crosscut 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.
○: It is not peeled off at all.
Δ: Some peeled off.
X: 50% or more peeling occurred.

7). Specific Resistance The sheet resistance and film thickness of the conductive laminate test piece were measured, and the specific resistance was calculated. Thickness gauge SMD-565L (manufactured by TECLOCK Co., Ltd.) was used for the film thickness, and the thickness of the cured coating film was measured at three 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 The conductive laminate test piece was placed on a 2 mm thick SUS304 plate, 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 of 85 ° C-85% RH and treated for 120 hr. A cross cut of 100 squares of 10 squares in total was formed, and cellophane tape peeling was performed. And the peeling condition of the coating film on an ITO film was evaluated visually. The evaluation criteria are as follows.
○: It is not peeled off at all.
Δ: Some peeled off.
X: 50% or more peeling occurred.

10. Evaluation of fine line printability As a printing plate used for gravure offset printing, a nickel electroformed flat intaglio having a plurality of concave patterns with a line width of 30 μm, a depth of 20 μm and a pitch of 60 μm is used as a printing substrate, and PET film (Cosmo manufactured by Toyobo Co. Shine A4300) was prepared. Further, a silicone blanket having a thickness of 0.6 mm was used as a printing blanket. First, a predetermined amount of 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 where it was pressed against the flat intaglio, and slid on the flat intaglio to receive the conductive paste embedded in the concave pattern of the flat intaglio on the surface of the silicone blanket. Finally, the silicone blanket was rotated while 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 printed matter, L / S was measured with a digital microscope VHX-2000 (manufactured by Keyence Co., Ltd.), the state of the fine line was observed, and the fine line printability was evaluated according to the following criteria.
○: There is no disconnection and there is no short circuit between the thin wires.
×: There is a partial disconnection or a short circuit between the thin wires.

11. Preparation of conductive paste Each component was blended at a blending ratio (mass ratio) shown in Tables 1 and 2 and kneaded by a three-roll mill to obtain 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: P-2013 manufactured by Kuraray Co., Ltd. (number average molecular weight 2,000, acid value 3 eq / ton, hydroxyl value 54.4 KOHmg / g)
Polyester polyol 2: P-2030 manufactured by Kuraray Co., Ltd. (number average molecular weight 2,000, acid value 4 eq / ton, hydroxyl value 55.4 KOHmg / g)
Polyester polyol 3: P-1030 manufactured by Kuraray Co., Ltd. (number average molecular weight 1,000, acid value 3 eq / ton, hydroxyl value 111.3 KOHmg / g)
Polyester polyol 4: F-3010 manufactured by Kuraray Co., Ltd. (number average molecular weight 3,000, acid value 5 eq / ton, hydroxyl value 55.8 KOHmg / g)
Block isocyanate 1: Trixene BI 7982 manufactured by Baxenden (solid content: 70% by weight, isocyanate theoretical value: 10.2% by weight)
Block isocyanate 2: Trixene BI 7992 manufactured by Baxenden (solid content: 70% by weight, isocyanate theoretical value: 9.2% by weight)
Block isocyanate 3: Trixene BI 7950 manufactured by Baxenden (solid content 65 wt%, isocyanate theoretical value 7.4 wt%)
Silver powder 1: Fukuda Metal Foil Powder Industry Co., Ltd. AgC-251 (D50 = 1.8 μm, flaky silver powder)
Silver powder 2: Ferro Japan SF30 (D50 = 1.0 μm, flaky silver powder) Silver powder 3: DOWA Hightech Co., Ltd. G-35 (D50 = 6.1 μm, aggregated silver powder)
Silver powder 4: DOWA Hi-Tech Co., Ltd. AG-2-1C (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: Disperbyk 2155 manufactured by Big Chemie Japan Co., Ltd.
Leveling agent 1: Kyoeisha Chemical Co., Ltd. MK Conch

12 Evaluation Results Examples 1 to 7 Tables 3 and 4 show the results of various evaluations performed on the conductive pastes of 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 for the production of printed wiring used in various electronic devices. It can also be used for electromagnetic shielding applications, circuit formation applications for electronic components, and conductive adhesives for terminals and lead wires.

Claims

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), wherein the thermoplastic resin (A) is hot A polyurethane resin 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. A conductive paste, which is a polyester resin, wherein the thermoplastic resin (B) is an amorphous polyol and has a number average molecular weight of 500 to 6,000.
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.
3. The conductive paste according to claim 1, wherein the thermoplastic resin (B) is a polyester polyol and / or a polyether polyol and / or a polycarbonate polyol.
The conductive paste according to any one of claims 1 to 3, wherein the acid value of the nonvolatile organic component in a heat treatment at 130 ° C for 30 minutes is 20 to 500 eq / ton.
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 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 4, wherein the isocyanate group is 20 to 200 mol%.
The conductive paste according to any one of claims 1 to 5, wherein the organic solvent (E) has a boiling point of 100 ° C or higher and a weight fraction based on the total weight of the conductive paste is 25% by weight or less.
The conductive paste according to claim 1, wherein the conductive powder (D) is mainly composed of silver.
Gravure offset printing (The conductive paste is filled into 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 on the substrate to be printed from the printing blanket. The conductive paste according to any one of claims 1 to 7, which is used in a method of transferring an electrically conductive paste to a substrate and printing and forming an electrode pattern.
Printing the conductive paste according to any one of claims 1 to 7 by gravure offset printing (filling a conductive paste with a printing plate having a concave pattern, and a silicone rubber sheet on the surface of the filled conductive paste) After receiving into the blanket for printing, the conductive paste is transferred from the printing blanket onto the substrate to be printed, and the resulting conductive coating is dried and / or cured) The printed matter obtained.
The printed matter according to claim 9, wherein the line / space pitch is 100 μm or less.
A conductive laminate obtained by laminating the printed matter according to claim 9 on a transparent conductive layer.
A touch panel using the conductive laminate according to claim 11.