WO2018092762A1 - Conductive paste, conductive film, method for producing conductive film, conductive thin wiring line and method for producing conductive thin wiring line - Google Patents

Abstract

[Problem] To provide a conductive paste which enables the achievement of a conductive film that has excellent laser etching properties and is useful for the formation of a thin wiring line. [Solution] After mixing and dispersing a silver powder having a central particle diameter D50 of from 0.5 μm to 5 μm (inclusive) and preferably having a tap density of 2.0 g/cm³ or more, a binder resin containing 60% by weight or more of a phenoxy resin having a number average molecular weight of 3,000 to 100,000 and an acid value of 20 eq./10⁶ to 500 eq./10⁶, a solvent and a dispersant that is preferably in a solid state at 25°C or higher, the resulting dispersion mixture is filtered, thereby obtaining a conductive paste which has a degree of dispersity of 10 μm or less as determined with a grind gage as specified by ISO 1524 (2013). According to the present invention, a thin wiring line is obtained by applying the thus-obtained conductive paste to a device material, on which an inorganic thin film has been formed, and subsequently drying and curing the conductive paste and then subjecting the resulting conductive paste to laser etching.

Description

A conductive paste, a conductive film, a method for manufacturing a conductive film, a conductive fine wiring, and a method for manufacturing a conductive fine wiring.

An object of the present invention is to provide a conductive paste that is suitably used for forming fine wiring formed close to a transparent conductive thin film used in a touch panel or the like. In printed electronics, An object of the present invention is to provide a conductive paste capable of producing an electrode circuit wiring having high surface smoothness without problems when forming a TFT base electrode.

In recent years, electronic devices equipped with a transparent touch panel represented by mobile phones, notebook computers, electronic books, and the like are rapidly increasing in performance and size. In order to improve the performance and miniaturization of these electronic devices, it is necessary to increase the density of the electrode circuit wiring that joins these electronic components in addition to the reduction in size, performance, and integration of the electronic components. It has been. As a transparent touch panel method, in addition to the resistive film method with a small number of electrode circuit wirings, the use of a capacitive method with a remarkably large number of electrode circuit wirings has been rapidly spreading in recent years. High density is strongly demanded. In addition, in order to make the display screen larger and due to demands on product design, there is a demand for a narrower frame portion on which the electrode circuit wiring is arranged. From this viewpoint, the density of the electrode circuit wiring is high. Is required. In order to satisfy the above requirements, there is a demand for a technique capable of performing higher-density arrangement of electrode circuit wiring than in the past.

The arrangement density of the electrode circuit wiring in the frame part of the transparent touch panel of the resistive film type is about 200 μm (hereinafter abbreviated as L / S = 200/200 μm) in the width of the line and the space in the plane direction. Conventionally, this is formed by screen printing of a conductive paste. In the capacitive touch panel, the L / S requirement is about 100/100 μm or less, and there are cases where the L / S is required to be 50/50 μm or less. The situation is becoming difficult to deal with.

As an example of a candidate electrode circuit wiring forming technique that replaces screen printing, a photolithography method can be cited. If a photolithography method is used, it is possible to form a thin line having an L / S of 50/50 μm or less. However, there are also problems with photolithography. The most typical example of photolithography is a method using a photosensitive resist. Generally, a photosensitive resist is applied to a copper foil portion of a surface substrate on which a copper foil layer is formed, and a photomask or a laser beam is used. A desired pattern is exposed by a method such as direct drawing, the photosensitive resist is developed, and then a copper foil portion other than the desired pattern is dissolved and removed with a chemical to form a fine line pattern of the copper foil. For this reason, the environmental load by waste liquid processing is large, and also the process is complicated, and it has many problems including the viewpoint of production efficiency and the viewpoint of cost.

Furthermore, in recent printed electronics, technology for producing active elements such as transistors by printing is being realized. In such an application, it is required to have a uniform film thickness and a thin film simultaneously with fine wiring.

Patent Document 1 discloses an application step of applying a paste made of inorganic powder, a carboxyl group-containing resin, glass frit, and a solvent on a substrate, and drying the applied paste to dry the applied paste. There is disclosed a pattern forming method including a process, a laser irradiation process for drawing a pattern on the dry coating film by laser irradiation, and a development process for developing the pattern using an alkaline solution. This proposal is different from general photolithography in that patterning is performed by removing the resin component in the paste resin component using a laser, but the disadvantage of the conventional photolithography method is that it requires cleaning with an alkaline solution. It cannot be said that it has been resolved.

Patent Document 2 discloses a coating process in which a paste containing AlN powder, glass frit, and a solvent is coated on a substrate, a drying process in which the paste coated is dried to form a dry coating film, and a kite laser light irradiation. A conductive film comprising: a laser drawing process for drawing a conductive pattern on the dried coating film; and a developing process for removing an unirradiated portion of the laser beam in the dried coating film using a developer. A pattern forming method is disclosed. This invention is also similar to the above technique in that a laser is used for patterning, and cannot be said to have solved the disadvantages of the conventional photolithography method in that cleaning is essential.

The present applicants have proposed the technique shown in Patent Document 3 with the aim of eliminating such a situation. That is, an acid value of 50 to 300 eq. / 10 ⁶ g of polyester resin and an acid value of 50 to 300 eq. The binder resin (A) contains a binder resin (A), a metal powder (B), and an organic solvent (C) made of one or a mixture of two or more selected from the group consisting of polyurethane resins that are / 10 ⁶ g. ) Is a thermoplastic paste having a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of 60 to 100 ° C. According to the technique disclosed in this proposal, it is possible to process a fine line by removing the entire conductive layer of an unnecessary portion by thermal ablation with high-power laser light. However, for further miniaturization and narrow pitch, it is necessary to reduce not only the line width but also the line-to-line width, and further improvements have been required in this technology.

JP 2010-237573 A JP 2011-181338 A Japanese Patent Laying-Open No. 2015-127958

An object of the present invention is to provide a conductive paste suitably used for forming fine wiring formed close to a transparent conductive thin film used for a touch panel or the like, and also to form a TFT base electrode. It is an object of the present invention to provide a conductive paste that can produce electrode circuit wiring having high surface smoothness without problems.

As a result of intensive studies on a conductive paste on which electrode circuit wiring having high surface smoothness is disposed, the present inventors have found a conductive paste suitable for forming a conductive film. That is, this invention consists of the following structures.
[1] In a conductive paste containing at least a binder resin composed of a thermoplastic and / or thermosetting resin, silver powder, and an organic solvent,
The center diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less,
The binder resin has a number average molecular weight of 3,000 to 100,000 and an acid value of 20 to 500 eq. A conductive paste characterized by containing 60% by weight or more of / 10 6 phenoxy resin.
[2] Surface roughness Ra by applying the conductive paste according to [1] on a polymer film on which an inorganic thin film layer having a surface with a surface roughness of 0.1 μm or less is formed and drying and curing. Of a conductive film having a thickness of 0.4 μm or less.
[3] Based on either a polymer film or a polymer film having an inorganic thin film layer having a surface roughness of 0.1 μm or less on the surface,
The number average molecular weight is at least 3,000 to 100,000, and the acid value is 20 to 500 eq. Conductive fine wiring comprising a cured phenoxy resin of 10 6 and conductive particles, and having a line width of 100 μm or less and a line width of 100 μm or less.
[4] The conductive fine wiring according to [3], wherein a line width of the conductive fine wiring is 50 μm or less and a line width is four times or less of a thickness of the conductive film. .
[5] The conductive fine wiring according to [3] or [4], wherein the conductive fine wiring has a line width of 50 μm or less and 3.5 times or less of the thickness of the conductive film. .
[6] The method for producing a conductive fine wiring according to any one of [3] to [5], wherein unnecessary portions of the conductive film according to [2] are removed with a laser beam.

The present invention further has the following configuration.
[7] In a conductive paste containing at least a binder resin composed of a thermoplastic and / or thermosetting resin, silver powder, and an organic solvent,
The center diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less,
The silver powder tap density is 2.0 g / cm3 or more,
The binder resin contains 60% by weight or more of a phenoxy resin having a number average molecular weight of 3,000 to 100,000, and has a dispersion obtained by Grind Gage defined in ISO 1524: 2013 of 10 μm or less. A conductive paste.
[8] At least 60% by weight of silver powder having a center diameter D50 of 0.5 μm or more and 5 μm or less and a tap density of 2.0 g / cm ³ or more, and a phenoxy resin having a number average molecular weight of 3,000 to 100,000 The composition containing the binder resin, solvent, and dispersant contained above is mixed and dispersed by a three-roll mill, and then filtered through a filter having an opening of 1 μm to 25 μm. Method.
[9] By subjecting the conductive paste obtained by the production method of [8] to screen printing on a polymer film on which an inorganic thin film layer having a surface with a surface roughness of 0.1 μm or less is formed, and then drying and curing A method for producing a conductive film having a surface roughness Ra of 00.4 μm or less.
[10] An unnecessary portion of the conductive film obtained by the manufacturing method of [9] is removed with a laser beam. The surface roughness Ra is 0.4 or less, and the line width is 100 μm or less. Yes, a method for manufacturing conductive fine wiring in which the distance between lines is 100 μm or less.

Further, the present invention preferably includes the following configuration.
[11] The conductive paste according to [1], wherein the dispersion obtained by Grind Gage specified in ISO 1524: 2013 is 10 μm or less.
[12] The method for producing a conductive paste according to [1] or [11], wherein the mixture is dispersed through a filter having an opening of 1 μm or more and 25 μm after the dispersion.

Further, the present invention preferably includes the following configuration.
[15] At least a reaction cured product composed of a phenoxy resin having a number average molecular weight of 3000 to 100,000 and a blocked isocyanate, and silver powder having a center diameter D50 of 0.5 μm or more, and the surface roughness Ra of the coating film is 0.00. A conductive coating film for laser etching, characterized by being 4 or less.
[16] The method for producing a conductive paste according to [2], wherein the dispersant is solid at 25 ° C., and silver powder, a solvent solution of a binder resin, and a dispersant are mixed and dispersed all at once.
[17] The conductive paste according to [7], wherein the acid value of the phenoxy resin is 20 equivalents / 10 ⁶ g or more and 500 equivalents / 10 ⁶ g or less.
[18] The method for producing a conductive paste according to [8], wherein the acid value of the phenoxy resin is 20 equivalents / 10 ⁶ g or more and 500 equivalents / 10 ⁶ g or less.
[19] The method for producing a conductive film according to [9], wherein the acid value of the phenoxy resin is 20 equivalents / 10 ⁶ g or more and 500 equivalents / 10 ⁶ g or less.
[20] The method for producing a conductive fine wiring according to [10], wherein the acid value of the phenoxy resin is 20 equivalents / 10 ⁶ g or more and 500 equivalents / 10 ⁶ g or less.

The conductive paste of the present invention has an acid value of 20 to 500 eq. The surface roughness Ra of the coating film formed by screen printing is 0.4 μm or less by using a / 10 ⁶ phenoxy resin as a binder, and a conductive film having excellent adhesion to the substrate after the wet heat test can be formed. This is a conductive paste, and by adopting such a configuration, both line width and line width can be miniaturized. Fine wiring required for touch panels and TFT gate electrodes by printed electronics, base, collector, A conductive film suitable for an emitter electrode or the like can be formed.
The conductive paste of the present invention is a conductive paste containing an organic component containing a thermoplastic and / or thermosetting resin, silver powder and an organic solvent, and includes a binder resin in the organic component, and is formed by screen printing. The coated film has a surface roughness Ra of 0.4 μm or less, and a conductive film suitable for a TFT base electrode can be formed by adopting such a configuration.
In the present invention, the paste is preferably mixed and dispersed by a specific blending method, and a predetermined degree of dispersion is obtained through a filtration step. As a result, a conductive film having a smooth surface and excellent laser etching suitability can be obtained. it can.

<< Components constituting the conductive paste of the present invention >>
The conductive paste of the present invention contains an organic component containing thermoplastic and / or thermosetting resin, silver powder and an organic solvent, and contains a binder resin as an essential component in the organic component. The organic component in the present invention refers to all parts excluding the inorganic component and the organic solvent in the conductive paste.

<Binder resin>
In the present invention, the number average molecular weight is 3,000 to 100,000, and the acid value is 20 to 500 eq. A binder resin containing 60% by weight or more of / 10 6 phenoxy resin is essential.
The phenoxy resin in the present invention is a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin. Examples of the phenoxy resin used as the binder resin in the present invention include bisphenol A type, bisphenol A / F copolymer type, bisphenol S type, and bisphenol A / S copolymer type. Among these, from the viewpoint of adhesion to the substrate, a phenoxy resin obtained from bisphenol A type can be preferably used.
The acid value of the phenoxy resin in the present invention is 20 eq. / 10 ⁶ g or more and 500 eq. / 10 ⁶ g or less, preferably 30 eq. / 10 ⁶ g or more and 200 eq. / 10 ⁶ g or less is more preferable. The acid value in the organic component improves the substrate adhesion, particularly the adhesion after the wet heat test, but if it is too high, the hydrolysis of the organic component is promoted and the conductivity and substrate adhesion may be impaired. In addition, there is a possibility of adversely affecting migration resistance.

In order to keep the acid value of the phenoxy resin within a predetermined range, the phenoxy resin is reacted with an acid anhydride. In the present invention, trimellitic anhydride, pyromellitic anhydride, hydrogenated trimellitic acid, phthalic anhydride, maleic anhydride and the like can be used as the acid anhydride. As the catalyst, a pyridine catalyst, dimethylaminopyridine, diazabicycloundecene and the like can be used. In addition, a method of adjusting a predetermined acid value by blending a high acid value phenoxy resin and a low acid value phenoxy resin is also effective.

In the present invention, a resin other than a phenoxy resin having a predetermined acid value can be blended. The type of binder resin is not particularly limited as long as it is a thermoplastic resin, but polyester resin, epoxy resin, phenoxy resin, polyamide resin, polyamideimide resin, polycarbonate resin, polyurethane resin, phenol resin, acrylic resin, polystyrene, styrene-acrylic resin , Styrene-butadiene copolymer, phenol resin, polyethylene resin, polycarbonate resin, phenol resin, alkyd resin, styrene-acrylic resin, styrene-butadiene copolymer resin, polysulfone resin, polyethersulfone resin, vinyl chloride-vinyl acetate Examples thereof include copolymer resins, ethylene-vinyl acetate copolymer, polystyrene, silicone resins, and fluorine resins. These resins can be used alone or as a mixture of two or more. Can. One or a mixture of two or more selected from the group consisting of a polyester resin, a polyurethane resin, an epoxy resin, a phenoxy resin, a vinyl chloride resin, and a fiber derivative resin is preferable. .

The number average molecular weight of the phenoxy resin in the present invention is not particularly limited, but the number average molecular weight is preferably 3,000 to 100,000, more preferably 8,000 to 50,000. If the number average molecular weight is too low, it is not preferable in terms of durability and heat and humidity resistance of the formed conductive film. On the other hand, when the number average molecular weight is too high, the cohesive force of the resin increases and the durability as a conductive film is improved, but the surface smoothness is significantly deteriorated.

The glass transition temperature of the phenoxy resin in the present invention is preferably 60 ° C. or higher, and more preferably 65 ° C. or higher. If the glass transition temperature is low, the reliability after wet heat as a conductive film may be reduced, and the surface hardness may be reduced, and the tack content may cause transfer of paste-containing components to the contact partner during use. There is a possibility that the reliability of the conductive film is lowered. On the other hand, the glass transition temperature of the binder resin is preferably 150 ° C. or less, more preferably 120 ° C. or less, and still more preferably 100 ° C. or less in consideration of printability, adhesion, solubility, and paste viscosity.

<Silver powder>
The shape of the silver powder used in the present invention is not particularly limited. Examples of conventionally known shapes include flakes (flakes), spheres, dendrites (dendrites), and spherical primary particles described in JP-A-9-306240 are three-dimensional. Are aggregated shapes (aggregated).

The center diameter (D50) of the silver powder used in the present invention is preferably 0.5 μm or more. When the one having a center diameter of 0.5 μm or less is used, the conductive path is not formed well and there is a possibility that the conductivity is deteriorated. Further, when the particle size is small, the particles are likely to aggregate and as a result, dispersion becomes difficult. Therefore, the center diameter is preferably 0.5 μm or more.

The central diameter (D50) is the particle diameter (μm) at which the cumulative value is 50% in the cumulative distribution curve (volume) obtained by some measurement method. In the present invention, the cumulative distribution curve is measured in the total reflection mode using a laser diffraction / scattering particle size distribution measuring apparatus (MICROTRAC HRA manufactured by Nikkiso Co., Ltd.).

The tap density of the silver powder used in the present invention is preferably 2.0 g / cm ³ or more. If the tap density is low, the degree of silver filling in the coating film becomes low, and as a result, the surface smoothness deteriorates. The upper limit of the tap density is not particularly limited, but is preferably 9.0 g / cm ³ , more preferably 7.5 g / cm ³ , and further preferably 5.5 g / cm ³ .

The silver powder content is preferably 400 parts by mass or more and more preferably 560 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint that the conductivity of the formed conductive film is good. In addition, the content of the component is preferably 1,900 parts by mass or less, more preferably 1,230 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin, from the viewpoint that the adhesiveness with the base material is good. .

<Organic solvent>
The organic solvent that can be used in the present invention is not particularly limited, but from the viewpoint of keeping the volatilization rate of the organic solvent within an appropriate range, the boiling point is preferably 100 ° C. or more and less than 300 ° C., more preferably the boiling point. It is 150 degreeC or more and less than 280 degreeC. The conductive paste of the present invention is typically prepared by dispersing a thermoplastic resin, silver powder, an organic solvent and other components as necessary with a three-roll mill or the like. In this case, the boiling point of the organic solvent is low. If the amount is too large, the solvent volatilizes during dispersion, and the component ratio of the conductive paste may change. On the other hand, if the boiling point of the organic solvent is too high, a large amount of the solvent may remain in the coating film depending on the drying conditions, which may cause a decrease in the reliability of the coating film.

The organic solvent that can be used in the present invention is preferably a solvent in which the binder is soluble and the silver powder can be well dispersed. Specific examples include ethyl diglycol acetate (EDGAC), butyl glycol acetate (BMGAC), butyl diglycol acetate (BDGAC), cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, Exson Chemical's Solvesso 100, 150, 200, a mixture of dimethyl ester of propylene glycol monomethyl ether acetate, adipic acid, succinic acid and glutaric acid (for example, DBE manufactured by DuPont Co., Ltd.), terpionol, etc. Among them, dissolution of binder resin EDGAC, BMGAC, BDGAC, and mixed solvents thereof are preferred from the viewpoints of excellent properties, moderate solvent volatility during continuous printing, and good suitability for printing by a screen printing method or the like.

The content of the organic solvent is preferably 5 to 40 parts by weight, more preferably 10 to 35 parts by weight, based on 100 parts by weight of the total paste. If the content of the organic solvent is too high, the paste viscosity becomes too low, and it tends to cause sagging during fine line printing. On the other hand, when the content of the organic solvent is too low, the viscosity as a paste becomes extremely high, and for example, screen printing properties when forming a conductive film may be significantly reduced.

Carbon filler can be added to the conductive paste of the present invention. Examples include carbon-based fillers such as carbon black, graphite powder, and ketjen black. The content of the carbon-based filler is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 2 parts by weight with respect to 100 parts by weight of silver powder.

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; titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica, fumed silica (for example, Japan) Aerosil) and other oxides such as colloidal silica; various titanate compounds such as calcium titanate, magnesium titanate and strontium titanate; sulfides such as molybdenum disulfide; magnesium fluoride and carbon fluoride Fluoride; aluminum stearate, calcium stearate, 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. Especially, in the electrically conductive paste of this invention, a fumed silica is preferable from a viewpoint of providing durability, printability, especially screen printability.

In the conductive paste of the present invention, a dispersant, a surface conditioner, an antifoaming agent, and a rheology control agent can be blended as additives. Furthermore, a carbodiimide, an epoxy, etc. can also be mix | blended suitably. These can be used alone or in combination. These may be added to the paste to change the rheology of the paste and improve the surface smoothness.

Examples of the dispersant include Disperbyk-2155, and monocarboxylic acids such as lauric acid, myristic acid, palmitic sun, margaric acid, stearic acid, terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalene. Aromatic dicarboxylic acid such as dicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, dicarboxylic acid such as azelaic acid, maleic acid, dimer acid etc. Dibasic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methyl Hexahydrophthalic anhydride, dicarboxy hydrogenated bisphenol A Dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalenedicarboxylic acid, alicyclic dicarboxylic acids such as tricyclodecane acid, hydroxybenzoic acid, and hydroxycarboxylic acids such as lactic acid. Further, trivalent or higher carboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid, and carboxylic acid diols such as dimethylolbutanoic acid and dimethylolpropionic acid.

In the present invention, among these, it is preferable to use an aliphatic monocarboxylic acid or aliphatic dicarboxylic acid solid at 25 ° C. as a dispersant. Specifically, dicarboxylic acids such as lauric acid, myristic acid, palmitic sun, margaric acid, stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, azelaic acid, maleic acid Etc. can be illustrated.
In the present invention, among these solid fatty acids, a compound having a melting point at 60 ° C. to 150 ° C. is preferred as a dispersant. Such a dispersant volatilizes and precipitates under the temperature conditions at the time of paste curing, but at the same time, the dispersant liquefies and reaches an effect of smoothing the paste cured film.

As other surface conditioners, antifoaming agents, leveling agents, and rheology control agents in the present invention, known additives used for inks or pastes may be used as necessary.

<Curing agent>
You may mix | blend the hardening | curing agent which can react with binder resin to the conductive paste of this invention to such an extent that the effect of this invention is not impaired. By blending a curing agent, there is a possibility that the curing temperature becomes high and the load of the production process is increased.

The type of the curing agent capable of reacting with the binder resin of the present invention is not limited, but is preferably an isocyanate compound and / or an epoxy resin in view of adhesion, flex resistance, curability and the like. Furthermore, regarding the isocyanate compound, it is preferable to use a blocked isocyanate group since 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, and phenol resins. These curing agents can be used in combination with a known catalyst or accelerator selected according to the type. The blending amount of the curing agent is blended to such an extent that the effects of the present invention are not impaired, and is not particularly limited, but is 0.5 to 50 parts by mass with respect to 100 parts by mass of the binder resin. It is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass.

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 isocyanate group blocking agent include phenols such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol; oximes such as acetoxime, methyl ethyl 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; tertiary alcohols such as t-butanol and t-pentanol ; Lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propylolactam, and the like, as well as aromatic amines, imides, acetylacetone, Seto acetate, active methylene compounds such as malonic acid ethyl ester, mercaptans, imines, imidazoles, ureas, diaryl compounds, sodium bisulfite, etc. can be mentioned. Of these, oximes, imidazoles, and amines are particularly preferable from the viewpoint of curability.

Examples of the epoxy compound used as a curing agent in the present invention include glycidyl ether types such as bisphenol A glycidyl ether, bisphenol S glycidyl ether, novolak glycidyl ether, and bromo bromide, hexahydrophthalic acid glycidyl ester, and dimer acid glycidyl ester Examples include glycidyl ester type, triglycidyl isocyanurate, or 3,4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, epoxidized soybean oil, and other alicyclic or aliphatic epoxides. You may use the above together. Among these, from the viewpoint of curability, bisphenol A glycidyl ether is most preferable, and among them, those having a molecular weight of less than 3000 and having two or more glycidyl ether groups in one molecule are more preferable.

<< Physical Properties Required for the Conductive Paste of the Present Invention >>
The viscosity of the electrically conductive paste of this invention is not specifically limited, What is necessary is just to adjust suitably according to the formation method of a coating film. For example, when the conductive paste is applied to the substrate by screen printing, the viscosity of the conductive paste is preferably 100 dPa · s or more, more preferably 150 dPa · s or more at the printing temperature. The upper limit is not particularly limited, but if the viscosity is too high, the surface smoothness may decrease.

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, and the solid content mass part is a mass part of components other than the solvent, and includes all of the conductive powder, organic components, other curing agents and additives. If the F value is too low, a conductive film showing good conductivity cannot be obtained. If the F value is too high, the adhesion between the conductive film and the substrate and / or the surface hardness of the conductive film tends to decrease. Yes, printability is inevitable. Here, the conductive powder refers to silver powder.

It is essential that the conductive paste of the present invention has a dispersity of 10 μm or less obtained by Grind Gage specified in ISO 1524: 2013. If the degree of dispersion exceeds this range, abnormal protrusions increase on the surface of the conductive film obtained from the paste, and the fine lines caused by laser etching are deteriorated.

<< Method for Producing Conductive Paste of the Present Invention >>
As described above, the conductive paste of the present invention can be prepared by dispersing an organic component, silver powder, an organic solvent, and other components as required with a three-roll roll or the like. Here, an example of a more specific production procedure is shown. First, the binder resin is dissolved in an organic solvent. Thereafter, silver powder, a dispersant, and other additives as necessary are added, and dispersion is carried out with a double planetary, a dissolver, a planetary stirrer, or the like. Then, it disperses | distributes with a 3 roll mill, and obtains an electrically conductive paste. The conductive paste thus obtained can be filtered if necessary. There is no problem even if the dispersion is performed using other dispersers such as a bead mill, a kneader, and an extruder.
In the present invention, it is preferable to use a dispersant that is solid at 25 ° C., and to mix and disperse the silver powder, the binder resin solvent solution, and the dispersant all at once.

In the present invention, filtration is performed after the materials are mixed and dispersed. The opening as a filter for filtering the conductive paste is not particularly limited, but a filter of 25 μm or less is preferable, more preferably 20 μm or less, and most preferably 15 μm or less. When a filter having a mesh size exceeding 25 μm is used, undispersed conductive powder, coarse particles, foreign matter, etc. cannot be removed, and a short circuit occurs between the fine wires after etching, resulting in poor yield.
On the other hand, the opening is preferably 1 μm or more, and if it is finer than this, depending on the particle diameter of the silver powder, the filtration rate is remarkably lowered, and finally the filtration filter is clogged. As a result, the number of filtration filter replacements increases, and the production efficiency decreases significantly.

Through the above steps, a conductive paste having a dispersity of 10 μm or less obtained by Grind Gage defined in ISO 1524: 2013 of the present invention can be obtained.

<< Conductive Film, Conductive Laminate and Production Method of the Present Invention >>
The conductive paste of the present invention is applied or printed on a substrate to form a coating film, and then the organic solvent contained in the coating film is volatilized to dry the coating film, thereby forming the conductive film of the present invention. be able to. The method for applying or printing the conductive paste on the substrate is not particularly limited, and can be applied to all printing methods such as gravure printing, offset printing, letterpress printing, ink jet printing, reverse printing, and micro contact printing. In particular, printing by a screen printing method is preferable because it is a technique that is widely used in the industry for forming an electric circuit using a conductive paste and a simple process.

The step of evaporating the organic solvent is preferably performed at room temperature and / or under heating. In the case of heating, since the conductivity, adhesion, and surface hardness of the conductive film after drying are improved, the heating temperature is preferably 80 ° C or higher, more preferably 100 ° C or higher, and further 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. When the curing agent is blended in the conductive paste of the present invention, the curing reaction proceeds when the step of evaporating the organic solvent is performed under heating.

The thickness of the conductive film of the present invention may be set to an appropriate thickness according to the intended use. However, from the viewpoint of good conductivity of the conductive film after drying, the film thickness of the conductive film is preferably 0.5 μm or more and 30 μm or less, more preferably 0.8 μm or more and 20 μm or less, Preferably they are 1.2 micrometers or more and 10 micrometers or less, and still more are 1.6 micrometers or more and 7 micrometers or less. If the thickness of the conductive film is too thin, there is a possibility that desired conductivity as a circuit cannot be obtained. In addition, the thickness of the conductive film affects the line width formed by laser etching and the width between lines. Therefore, it is better not to make the thickness more than necessary particularly when fine wiring is required.

The surface roughness Ra of the conductive film of the present invention is essential to be 0.40 μm or less. If the surface roughness Ra is too high, the scattering of the laser light becomes remarkable in the laser etching process, and the sharpness of the fine line (edge linearity) is lowered.

In the present invention, unnecessary portions of the conductive film obtained as described above are removed using laser light (laser etching) to obtain fine wiring. As the laser used in the present invention, a carbon dioxide laser, a YAG laser, a YVO laser, a fiber laser, a semiconductor laser, an excimer laser, or the like can be used.

In the present invention, conductive fine wiring having a line width of 100 μm or less and a line width of 100 μm or less can be formed by laser etching. In the present invention, the line width of the conductive fine wiring is preferably 50 μm or less, and the line width can be set to 4 times or less the thickness of the conductive film. Furthermore, in the present invention, the line width of the conductive fine wiring is 35 μm or less, and the line width can be 3.5 times or less of the thickness of the conductive film.

In the present invention, the thin line width obtained by laser etching is 100 μm or less, and in the present invention, it is possible to realize a line width of about 2.5 times the thickness of the conductive film. For example, the thickness of the conductive film is 10 μm. When the thickness is adjusted to 25, the minimum line width is 25 μm, and when the thickness of the conductive film is 5 μm, the line width is 12.5 μm.
In the present invention, the line width obtained by laser etching is 100 μm or less, and in the present invention, it is possible to realize a minimum line width of about 3 times the thickness of the conductive film. When adjusted to 10 μm, a minimum line width of 30 μm can be realized, and when the thickness of the conductive film is set to 5 μm, a minimum line width of 15 μm can be realized.

In order to describe the present invention in more detail, examples and comparative examples are given below, but the present invention is not limited to the examples. In addition, each measured value described in the Example and the comparative example was measured by the following method.

<Number average molecular weight>
The sample resin was dissolved in tetrahydrofuran so that the resin concentration was about 0.5% by weight, and filtered through a polytetrafluoroethylene membrane filter having a pore diameter of 0.5 μm to obtain a GPC measurement sample. GPC measurement of a resin sample using tetrahydrofuran as a mobile phase, a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation, and a differential refractometer (RI meter) as a detector at a column temperature of 30 ° C. and a flow rate of 1 ml / min. Was done. The number average molecular weight was a standard polystyrene equivalent value, and was calculated by omitting a portion corresponding to a molecular weight of less than 1000. As the GPC column, shodex KF-802, 804L and 806L manufactured by Showa Denko KK were used.

<Acid value 1>
0.2 g of sample resin was precisely weighed and dissolved in 20 ml of chloroform. Subsequently, titration was performed with 0.01 N potassium hydroxide (ethanol solution) using a phenolphthalein solution as an indicator. The unit of acid value is eq. / 10 ⁶ g, that is, equivalent per 1 metric ton of sample.

<Acid value 2>
A solution obtained by dissolving 0.1 g of resin in 10 ml of a mixed solvent of benzyl alcohol / chloroform (1/1 vol ratio) and 0.4 g of sodium hydroxide in a mixed solvent of benzyl alcohol / methanol (9/1 vol ratio) are dissolved. Measured by titrating with a prepared alkaline solution.

<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.

<Paste viscosity>
The viscosity was measured at 20 rpm using a BH viscometer (manufactured by Toki Sangyo Co., Ltd.) at a sample temperature of 25 ° C.

<Dispersity>
It was measured by Grind Gage specified in ISO 1524: 2013.
<Creation of conductive laminate test piece 1>
An electrically conductive paste is printed on a PET film (Lumirror S, manufactured by Toray Industries, Inc.) having a thickness of 100 μm by screen printing using a 400 mesh stainless screen to form a solid coating pattern having a width of 25 mm and a length of 450 mm. Then, what was heated at 130 degreeC for 30 minutes with the hot-air circulation type drying furnace was used as the electroconductive laminated body test piece. The coating thickness at the time of printing was adjusted so that the dry film thickness was 5 to 10 μm.

<Adhesion>
The conductive laminate test piece 1 was evaluated by a peel test using Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd.) according to JIS K-5400-5-6: 1990. However, the number of cuts in each direction of the lattice pattern was 11, and the cut interval was 1 mm. 100/100 indicates that there is no peeling and good adhesion, and 0/100 indicates that all are peeled off.

<Moist heat test>
The sample was exposed for 240 hours in a high-temperature and high-humidity tank adjusted to 85 ° C. and 85% RH at 1 atmosphere, and after having been leveled in a standard room for at least 24 hours, an adhesion test was conducted to evaluate the wet heat test.

<Resistivity>
The sheet resistance and film thickness of the conductive laminate test piece 1 were measured, and the specific resistance was calculated. For the film thickness, a gauge stand ST-022 (manufactured by Ono Sokki Co., Ltd.) was used, and the thickness of the cured coating film was measured at 5 points using the thickness of the PET film as a zero point, and the average value was used. The sheet resistance was measured for four test pieces using MILLIOHMMETER 4338B (manufactured by HEWLETT PACKARD), and the average value was used. The range that can be detected by this milliohm meter is 1 × 10 −2 (Ω · cm) or less, and a specific resistance of 1 × 10 −2 (Ω · cm) or more is outside the measurement limit.

<Surface roughness>
In the conductive laminate test piece 1, the surface roughness Ra was measured using a surface roughness meter (Handy Surf E-35B, Tokyo Seimitsu Co., Ltd., calculated based on JIS-1994).

<Laser etching property>
Conductive paste is applied to a 2.5 x 10 cm rectangle on the polyester base ITO on which the ITO thin film has been formed by screen printing, using screen printing. The conductive thin film was obtained by drying at 120 ° C. for 30 minutes. The surface roughness R of the ITO tatami mat was 0.3 μm. Further, the printing conditions and the like were adjusted so that the film thickness was 4 to 6 μm. Next, laser etching is performed on the conductive thin film prepared by the above method, the line width / interline width shown below is drawn, and the presence or absence of fine wiring formation is observed with a microscope at each set line width / interline width. Confirmation by the presence or absence of short circuit between wires, and when the wiring part of 100mm or more length is conducting, and when the width of the line of 100mm or more length is not electrically short-circuited, fine wiring can be formed. It was determined.
Line width / line width = 100 μm / 100 μm
Line width / line width = 70 μm / 70 μm
Line width / line width = 50 μm / 50 μm
Line width / line width = 50 μm / 40 μm
Line width / line width = 50 μm / 35 μm
Line width / line width = 50 μm / 30 μm
Line width / line width = 50 μm / 25 μm
Line width / line width = 50 μm / 20 μm
Line width / line width = 40 μm / 40 μm
Line width / line width = 40 μm / 35 μm
Line width / line width = 40 μm / 30 μm
Line width / line width = 40 μm / 25 μm
Line width / line width = 40 μm / 20 μm
Line width / line width = 40 μm / 15 μm
Line width / line width = 35 μm / 35 μm
Line width / line width = 35 μm / 30 μm
Line width / interline width = 35 μm / 25 μm
Line width / line width = 35 μm / 20 μm
Line width / line width = 35 μm / 15 μm
Line width / inter-line width = 35 μm / 10 μm
Line width / line width = 30 μm / 30 μm
Line width / line width = 30 μm / 25 μm
Line width / line width = 30 μm / 20 μm
Line width / line width = 30 μm / 15 μm
Line width / inter-line width = 30 μm / 10 μm
Line width / line width = 25 μm / 25 μm
Line width / line width = 25 μm / 20 μm
Line width / line width = 25 μm / 15 μm
Line width / interline width = 25 μm / 10 μm
Line width / inter-line width = 20 μm / 20 μm
Line width / line width = 20 μm / 15 μm
Line width / line width = 20 μm / 10 μm
Note that a YAG laser was used as the laser beam, and the minimum beam diameter was adjusted to be not more than half of the width between each line. In addition, a tester with an applied voltage of 1.5 V was used for the continuity of wiring and the presence or absence of a short circuit between lines.

<Synthesis example>
<Binder resin PH001>
Into a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 400 parts of InChem phenoxy resin PKHC was added, and then 489 parts of ethyl diglycol acetate (EDGAC) was charged and dissolved at 85 ° C. Thereafter, 1 part of trimellitic anhydride was added, 0.19 part of dimethylaminopyridine and 0.48 part of diazabicycloundecene were added as catalysts, and reacted at 85 ° C. for 4 hours to obtain a solution of phenoxy resin PH001. .
The solid content concentration of the obtained phenoxy resin solution was 35% by mass. The resin solution thus obtained was dropped on a polypropylene film and spread using a stainless steel applicator to obtain a resin solution thin film. This was left to stand in a hot air dryer adjusted to 120 ° C. for 3 hours to volatilize the solvent, and then the resin thin film was peeled off from the polypropylene film to obtain a film-like dry resin thin film, which was used for acid value measurement and the like.
Thereafter, the raw material was changed in the same manner to perform a modification operation, and acid-modified phenoxy resins shown in Table 1 were obtained.
[Example 1]
2857 parts (1000 parts in terms of solid part) of an acid-modified phenoxy resin PH001 shown in Table 1 dissolved in EDGAC so that the solid content concentration is 35% by mass, 8361 parts of flaky silver powder 1 and 100 of curing agent 1 Part, 59 parts of leveling agent, 34 parts of additive 1 and 164 parts of EDGAC as a solvent were mixed and dispersed twice by passing through a chilled three-roll kneader. Next, a 635 mesh (stainless mesh filter (aperture 20 μm) filter) was attached to the paste filter, and the paste was filtered. After that, the obtained conductive paste was printed in a predetermined pattern, and then 130 ° C. × After drying for 30 minutes, a conductive film was obtained, the basic physical properties were measured using this conductive film, the surface smoothness was then examined, and the wettability test and the fine wiring formability by laser etching were evaluated. The evaluation results are shown in Table 2.

 

In Table 1, phenoxy resin 1 InChme PKHC number average molecular weight 21000 Tg 67 ° C
Phenoxy resin 2 Nippon Steel & Sumikin Chemical YP-70 Number average molecular weight 28000 Tg 60 ℃
Phenoxy resin 3 made by Mitsubishi Chemical jER-1010 Number average molecular weight 8000 Tg 55 ℃
Phenoxy resin 4 Made by Mitsubishi Chemical jER-1002 Number average molecular weight 1000 Tg 54 ℃
(Tg: Glass transition temperature)
It is.

[Examples 2 to 11] [Comparative Examples 1 to 3]
Examples 2 to 11 and Comparative Examples 1 to 3 were carried out by changing the resin and composition of the conductive paste. The results are shown in Table 2. In the examples, good coating film physical properties could be obtained by heating at a relatively low temperature of 130 ° C. for 30 minutes in an oven. Also, the adhesion to the ITO film and the adhesion after the wet heat environment test were good. Furthermore, it showed good fine wire formability by laser etching.

 

In Table 2, binder resin RV-200:
Toyobo RV-200 (polyester resin, number average molecular weight 27000, Tg = 67 ° C.),
Silver powder 1: Agglomerated powder SF-2J (D50: 1.4 μm, tap density 3.8 g / cm ³ ),
Silver powder 2: Flake silver powder SF-70A (D50: 2.4 μm, tap density 3.0 g / cm ³ ),
Silver powder 3: Ag2-1C (D50: 0.9 μm, tap density 5.0 g / cm 3)
Silica: Nippon Aerosil Co., Ltd. # 300,
Carbon black: Ketjen ECP600JD made by Lion Co., Ltd.
Curing agent 1: MF-K60X manufactured by Asahi Kasei Chemicals Corporation
Hardener 2: BI-7960 from Baxenden
Curing catalyst: Kyodo Pharmaceutical Co., Ltd. KS1260,
Leveling agent: Kyoeisha Chemical Co., Ltd. MK Conch,
Dispersant 3: Oxalic acid dihydrate, melting point 101.5 ° C.
Dispersant 5: malonic acid melting point 135 ° C.
Dispersant 12: Margaric acid, melting point 61 ° C.,
EDGAC: Ethyl diglycol acetate manufactured by Daicel Corporation,
BDGAC: butyl diglycol acetate manufactured by Daicel Corporation,
It is.

[Example 21]
2857 parts of phenoxy resin PH-1 dissolved in EDGAC so that the solid content concentration is 35% by mass (1000 parts in terms of solid part), 8361 parts of flaky silver powder 1, 100 parts of curing agent 1, and a leveling agent 59 parts, 34 parts of additive 1 and 164 parts of EDGAC as a solvent were blended and dispersed by passing twice through a chilled three-roll kneader. Next, a 635 mesh (stainless mesh filter (aperture 20 μm) filter) was attached to the paste filter, and the paste was filtered. After that, the obtained conductive paste was printed in a predetermined pattern, and then 130 ° C. × The film was dried for 30 minutes to obtain a conductive film, the basic physical properties were measured using this conductive film, and then the surface smoothness was examined.

[Examples 22 to 53] [Comparative Examples 11 to 14]
Examples 22 to 53 and Comparative Examples 11 to 14 were carried out by changing the resin and the composition of the conductive paste. The formulation and evaluation results of the conductive paste are shown in Tables 3 to 6. In the examples, good coating film physical properties could be obtained by heating at a relatively low temperature of 130 ° C. for 30 minutes in an oven. Also, the adhesion to the ITO film was good.

In Tables 3 to 6, the following binder resins, conductive powders, additives and solvents were used.
Binder resin PH-1:
PKHB manufactured by InChem (phenoxy resin, number average molecular weight 16000, Tg = 64 ° C., acid value 3 equivalents / 10 ⁶ g)
Binder resin PH-2:
InChem PKHC (phenoxy resin, number average molecular weight 21000, Tg = 66 ° C., acid value 2 equivalents / 10 ⁶ g)
Binder resin PH-3: PKHC modified product manufactured by InChme (phenoxy resin, number average molecular weight 21000, Tg = 67 ° C., acid value 105 equivalent / 10 ⁶ g)
Binder resin PH-4:
PCHHH manufactured by InChem (phenoxy resin, number average molecular weight 27000, Tg = 67 ° C., acid value 2 equivalent / 10 ⁶ g)
Binder resin PH-5: YP-50 manufactured by Nippon Steel & Sumikin Chemical
(Phenoxy resin, number average molecular weight 27000, Tg = 65 ° C., acid value 3 equivalents / 10 ⁶ g)
Binder resin PH-6: YP-70 manufactured by Nippon Steel & Sumikin Chemical
(Phenoxy resin, number average molecular weight 28000, Tg = 60 ° C., acid value 1 equivalent / 10 ⁶ g)
Binder resin PH-7: Mitsubishi Chemical's jER-1010
(Phenoxy resin, number average molecular weight 8000, Tg = 55 ° C., acid value 2 equivalents / 10 ⁶ g)
Binder resin PH-8: Mitsubishi Chemical's jER-1002
(Phenoxy resin, number average molecular weight 1000, Tg = 54 ° C., acid value 3 equivalents / 10 ⁶ g)
Binder resin PS-1: Toyobo RV-200 (polyester resin, number average molecular weight 27000, Tg = 67 ° C.)
Silver powder 1: Agglomerated powder SF-2J (D50: 1.4 μm, tap density 3.8 g / cm ³ )
Silver powder 2: Flake silver powder SF-70A (D50: 3.0 μm, tap density 3.2 g / cm ³ )
Silver powder 3: AC-2594 (D50: 1.7 μm, tap density 5.0 g / cm ³ )
Silver powder 4: AGC-A (D50: 3.5 μm, tap density 3.3 g / cm ³ )
Silver powder 5: Ag2-1C (D50: 0.9 μm, tap density 5.0 g / cm ³ )
Silver powder 6: SFQ-ED (D50: 1.4 μm, tap density 2.7 g / cm ³ )
Silver powder 7: S11000-25 (D50: 0.3 μm, tap density 1.95 g / cm ³ )
Silica: Nippon Aerosil Co., Ltd. # 300
Ketjen Black (Carbon Black): Ketjen ECP600JD manufactured by Lion Corporation
Hardener 1: MF-K60X manufactured by Asahi Kasei Chemicals Corporation
Hardener 2: Baksenden BI-7960
Curing catalyst: Kyodo Pharmaceutical Co., Ltd. KS1260
Leveling agent: Kyoeisha Chemical Co., Ltd. MK Conk Additive 1: MK Conc (leveling agent)
Additive 2: BYK-410 (Rheology control agent) manufactured by Big Chemie Japan Co., Ltd.
Additive 3: BYK-405 (Rheology control agent) manufactured by Big Chemie Japan
Additive 4: jER-820 (epoxy)
Dispersant 1: Disperbyk 2155 (dispersant) manufactured by Big Chemie Japan Co., Ltd.
Dispersant 2: Disperbyk130 (dispersant) manufactured by Big Chemie Japan Co., Ltd.
Dispersant 3: Oxalic acid dihydrate, melting point 101.5 ° C.
Dispersant 4: Adipic acid melting point 152.1 ° C.
Dispersant 5: malonic acid melting point 135 ° C.
Dispersant 6: Succinic acid Melting point 184 ° C
Dispersant 7: Maleic acid Melting point 131 ° C.
Dispersant 8: fumaric acid,
Dispersant 9: Lauric acid, melting point 43.2 ° C.,
Dispersant 10: myristic acid, melting point 54.4 ° C
Dispersant 11: Palmitic Sun, melting point 62.9 ° C.
Dispersant 12: Margaric acid, melting point 61 ° C.,
Dispersant 13: Stearic acid, melting point 69.6 ° C.
EDGAC: Ethyl diglycol acetate manufactured by Daicel Corporation BDGAC: Butyl diglycol acetate manufactured by Daicel Corporation

The binder resin PH-3 was produced by the following operation.
<Binder resin PH-3>
Into a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 400 parts of InChem phenoxy resin PKHC was added, and then 489 parts of ethyl diglycol acetate (EDGAC) was charged and dissolved at 85 ° C. Thereafter, 3 parts of trimellitic anhydride was added, 0.19 part of dimethylaminopyridine and 0.48 part of diazabicycloundecene were added as catalysts, and reacted at 85 ° C. for 4 hours to obtain a solution of phenoxy resin PH-3. Obtained. The solid content concentration of the obtained phenoxy resin solution was 35% by mass. The resin solution thus obtained was dropped on a polypropylene film and spread using a stainless steel applicator to obtain a resin solution thin film. This was left to stand in a hot air dryer adjusted to 120 ° C. for 3 hours to volatilize the solvent, and then the resin thin film was peeled off from the polypropylene film to obtain a film-like dry resin thin film, which was used for various measurements.

 

 

 

 

As described above, the conductive paste of the present invention has a high degree of dispersion, the conductive film obtained from the paste of the present invention has a good laser etching property, and is combined with a conductive thin film such as ITO to make a touch panel. It can be used effectively as a member for an input / output interface such as. Further, it can be suitably used for a wiring layer such as a printed TFT that requires fine wiring.

Claims (10)

1. In a conductive paste containing at least a binder resin made of thermoplastic and / or thermosetting resin, silver powder and an organic solvent,
   The center diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less,
   The binder resin has a number average molecular weight of 3,000 to 100,000 and an acid value of 20 to 500 eq. A conductive paste characterized by containing 60% by weight or more of / 10 ⁶ phenoxy resin.
2. The conductive paste according to claim 1 is applied onto a polymer film on which an inorganic thin film layer having a surface with a surface roughness of 0.1 μm or less is formed, and is dried and cured to have a surface roughness Ra of 0.00. The manufacturing method of the electroconductive film | membrane which is 4 micrometers or less.
3. Based on either a polymer film or a polymer film having a surface roughness of 0.1 μm or less and an inorganic thin film layer on the surface,
   The number average molecular weight is at least 3,000 to 100,000, and the acid value is 20 to 500 eq. A conductive fine wiring comprising a cured phenoxy resin of / 10 ⁶ and conductive particles, having a line width of 100 μm or less and a line width of 100 μm or less.
4. 4. The conductive fine wiring according to claim 3, wherein a line width of the conductive fine wiring is 50 μm or less, and a line width is four times or less of a thickness of the conductive film.
5. 5. The conductive fine wiring according to claim 3, wherein the conductive fine wiring has a line width of 50 μm or less and a line width of 3.5 times or less of the thickness of the conductive film.
6. 6. The method for producing a conductive fine wiring according to claim 3, wherein unnecessary portions of the conductive film according to claim 2 are removed with a laser beam.
7. In a conductive paste containing at least a binder resin made of thermoplastic and / or thermosetting resin, silver powder and an organic solvent,
   The center diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less,
   The silver powder tap density is 2.0 g / cm ³ or more,
   The binder resin contains 60% by weight or more of a phenoxy resin having a number average molecular weight of 3,000 to 100,000, and has a dispersion obtained by Grind Gage defined in ISO 1524: 2013 of 10 μm or less. A conductive paste.
8. Silver powder having a center diameter D50 of 0.5 μm or more and 5 μm or less and a tap density of 2.0 g / cm ³ or more,
   A binder resin containing 60% by weight or more of a phenoxy resin having a number average molecular weight of 3,000 to 100,000;
   solvent,
   Dispersant,
   The method for producing a conductive paste according to claim 7, wherein the composition containing is mixed and dispersed by a three-roll mill and then filtered through a filter having an opening of 1 μm to 25 μm.
9. A surface roughness obtained by screen-printing the conductive paste obtained by the production method according to claim 8 on a polymer film on which an inorganic thin film layer having a surface with a surface roughness of 0.1 μm or less is formed, followed by drying and curing. A method for producing a conductive film having a thickness Ra of 0.4 μm or less.
10. An unnecessary portion of the conductive film obtained by the manufacturing method according to claim 9 is removed with a laser beam, the surface roughness Ra is 0.4 or less, the line width is 100 μm or less, A method for producing a conductive fine wiring having a gap of 100 μm or less.