TWI752117B - Conductive paste, conductive film, method for producing conductive film, conductive fine wiring, and method for producing conductive fine wiring - Google Patents

Abstract

The subject of this invention is to provide the electrically conductive paste which can realize the electrically conductive film which is effective when forming the fine wiring excellent in the laser etching property. The solution to this problem is to set the median diameter D50 to be 0.5 μm or more and 5 μm or less, ideally ^{a silver powder with a tap density of 2.0 g/cm 3} or more, and a number-average molecular weight of 3,000 to 3,000 wt % or more. 100,000 Binder resin of phenoxy resin with acid value of 20~500eq./10 ⁶ , solvent, ideal dispersant which is solid above 25℃ are mixed and dispersed, and then filtered to obtain in accordance with ISO 1524:2013 A conductive paste with a dispersion degree of 10 μm or less obtained by using the Grind Gage. The obtained conductive paste was applied to a machine on which the inorganic thin film was formed, dried and cured, and fine wiring was obtained by laser etching.

Description

Conductive paste, conductive film, method for producing conductive film, conductive fine wiring, and method for producing conductive fine wiring

The object of the present invention is to provide a conductive paste suitable for use in touch panels and the like to form fine wirings formed near transparent conductive films, and to provide printed electronics, when forming TFT base electrodes , the conductive paste of electrode circuit wiring with high surface smoothness can be produced without any problem.

In recent years, the performance enhancement and miniaturization of electronic devices equipped with transparent touch panels, represented by mobile phones, notebook personal computers, electronic books, etc., are rapidly progressing. In addition to the miniaturization, performance enhancement, and improvement of the stacking degree of the electronic components to be mounted, the high-performance and miniaturization of these electronic devices are also required to increase the density of the electrode circuit wiring that joins these electronic components to each other. . As for the type of transparent touch panel, in addition to the resistive film type with a small number of electrode circuit wirings, the popularization of the electrostatic capacitance type with a significantly larger number of electrode circuit wirings has rapidly progressed in recent years, and is strongly driven by such a viewpoint. High density of electrode circuit wiring is sought. In addition, in order to make the display screen larger, and due to the requirements of product design, there is a requirement to narrow the frame portion where the electrode circuit wiring is arranged. Considering this point of view, the high density of the electrode circuit wiring is also sought. In order to meet the above-mentioned requirements, a technology that can implement a high-density arrangement of electrode circuit wirings beyond that of the conventional ones is sought.

The arrangement density of the electrode circuit wiring in the frame part of the transparent touch panel of the resistive film type is about 200μm in width of the line (Line) and the space (Space) in the plane direction (hereinafter referred to as L/S=200/200μm) As mentioned above, the formation of this wiring by the screen printing of a conductive paste has been performed conventionally. In the electrostatic capacitance type touch panel, the L/S requirement is about 100/100μm or less, and sometimes the L/S is required to be 50/50μm or less, and the electrode circuit wiring is made by screen printing. Formation technology has gradually become difficult to cope with.

A photolithography method can be cited as an example of a candidate for a technique for forming electrode circuit wiring instead of screen printing. When the photolithography method is used, it is very likely to form thin lines with an L/S of 50/50 μm or less. However, there are still problems with lithography. The most typical embodiment of the photolithography method is a method of using a photoresist. Generally speaking, the photoresist is applied to the copper foil portion of the surface substrate on which the copper foil layer is formed, and then a photomask is used. A desired pattern is exposed by a method such as direct laser drawing, and the photoresist is developed, and then the copper foil portion other than the desired pattern is dissolved and removed with a chemical to form a thin line pattern of the copper foil. Therefore, the environmental load caused by the waste liquid treatment is large, the steps are complicated, and there are many problems including the viewpoint of production efficiency and the viewpoint of cost.

In addition, in recent years, in printed electronics, the technology of producing active components such as transistors has been gradually realized by printing. Also in this application, the uniformity and thinning of the film thickness are required as in the fine wiring.

Patent Document 1 discloses a pattern forming method comprising: a coating step of applying a paste composed of inorganic powder, carboxyl group-containing resin, glass frit, and a solvent on a substrate; and a drying step of applying the coated The above-mentioned paste is dried to form a dry coating film; in the laser irradiation step, a pattern is drawn on the above-mentioned dry coating film by means of laser irradiation; in the developing step, the above-mentioned pattern is developed using an alkaline solution. should mention The case is different from general photolithography in that the resin component in the paste resin component is removed by laser and patterning is performed, but the cleaning with an alkaline solution cannot be called a solution. Disadvantages of the conventional lithography method.

Patent Document 2 discloses a method of forming a conductive pattern, which is characterized by comprising: a coating step of coating a paste containing AlN powder, glass frit and a solvent on a substrate; a drying step of drying the coated paste and A dry coating film is formed; in the laser drawing step, the conductive pattern is drawn on the dry coating film by the irradiation of laser light; The aspect of using a laser in patterning of the invention is the same as the aforementioned technology, and the aspect that needs cleaning cannot be said to have solved the shortcomings of the conventional photolithography method.

The applicant of the present application and others have proposed the technology shown in Patent Document 3 in view of solving this situation. I.e. A laser etching conductive paste, characterized by comprising a polyester resin selected from the acid value and acid value 50 ~ 300eq. / 10 ⁶ g of 50 ~ 300eq. / 10 ⁶ g of polyethylene A binder resin (A), a metal powder (B), and an organic solvent (C) composed of one or a mixture of two or more of the group consisting of urethane resins, and the coefficient of the aforementioned binder resin (A) A thermoplastic resin with a mesh average molecular weight of 5,000 to 60,000 and a glass transition temperature of 60 to 100°C. According to the technology disclosed in this proposal, it is possible to perform thermal ablation with a high-output laser light to completely remove the conductive layer of an unnecessary portion to process fine lines. However, in terms of further finer lines and narrower pitches, not only the line widths but also the line widths need to be narrowed, and even this technology needs further improvement.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-237573

[Patent Document 2] Japanese Patent Laid-Open No. 2011-181338

[Patent Document 3] Japanese Patent Application Laid-Open No. 2015-127958

An object of the present invention is to provide a conductive paste suitable for use in touch panels and the like for the formation of fine wirings formed near a transparent conductive film, and to provide a TFT base electrode that can be produced without any problem. Conductive paste for electrode circuit wiring with surface smoothness.

The inventors of the present invention have found a conductive paste suitable for forming a conductive film as a result of intensive research on a conductive paste for arranging electrode circuit wiring with high surface smoothness. That is, the present invention is constituted as follows.

[1] A conductive paste comprising at least a binder resin made of thermoplastic and/or thermosetting resin, silver powder, and an organic solvent, wherein the median diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less. The aforementioned binder resin contains more than 60% by weight of a phenoxy resin with a number average molecular weight of 3,000 to 100,000 and an acid value of 20 to 500 eq./10 ^{6 g.}

[2] A method for producing a conductive film, comprising applying the conductive paste as described in [1] on a polymer film on which an inorganic thin film layer having a surface roughness of 0.1 μm or less has been formed and drying and curing to obtain a conductive film with a surface roughness Ra of 0.4 μm or less.

[3] A conductive fine wiring using 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 as a base material, the conductive fine wiring comprising at least The number average molecular weight is 3,000 to 100,000, and the acid value is 20 to 500eq./10 ⁶ g of a cured phenoxy resin and conductive particles. The line width is 100 μm or less, and the line width is 100 μm or less.

[4] The conductive fine wiring according to [3], wherein the conductive fine wiring has a width between lines of 50 μm or less, and the width between lines is 4 times or less the thickness of the conductive film.

[5] The conductive fine wiring according to [3] or [4], wherein the line width of the conductive fine wiring is 50 μm or less and 3.5 times or less the thickness of the conductive film.

[6] A method for producing a conductive fine wiring, which is a method for producing the conductive fine wiring as described in any one of [3] to [5], by applying the conductive fine wiring as described in [2] Unwanted parts of the film are removed with laser light.

The present invention further has the following constitution.

[7] A conductive paste comprising at least a binder resin made of thermoplastic and/or thermosetting resin, silver powder, and an organic solvent, wherein the median diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less. , the tap density (tap density) of the aforementioned silver powder is 2.0 g/cm ³ or more, and the aforementioned binder resin contains more than 60% by weight of a phenoxy resin with a number-average molecular weight of 3,000-100,000, and is specified in accordance with ISO 1524:2013 The degree of dispersion obtained by the Grind Gage is 10 μm or less.

[8] A method for producing a conductive paste, which is the method for producing the conductive paste according to [7], characterized in that: after mixing and dispersing the following components with a three-roll mill, the following components are mixed and dispersed with a diameter of 1 μm. The composition is filtered with a filter of 25 μm or less, and the composition contains at least: a median diameter D50 of 0.5 μm or more and 5 μm or less, a tap density of 2.0 g/cm ³ or more of silver powder, and a number average molecular weight of 60% by weight or more of 3,000~100,000 phenoxy resin binder resin, solvent, and dispersant.

[9] A method for producing a conductive film, comprising screen-printing the conductive paste obtained by the method for producing a conductive paste according to [8] on a surface formed with a surface roughness of 0.1 μm or less The polymer film of the inorganic thin film layer is dried and hardened to obtain a conductive film with a surface roughness Ra of 0.4 μm or less.

[10] A method for producing conductive fine wiring, characterized by removing unnecessary portions of a conductive film obtained by the method for producing a conductive film as described in [9] by laser light to obtain surface roughness Conductive fine wiring with Ra of 0.4 μm or less, a line width of 100 μm or less, and a line-to-line width of 100 μm or less.

In addition, the present invention preferably includes the following constitutions.

[11] The conductive paste according to [1], having a degree of dispersion of 10 μm or less by the fineness meter specified in ISO 1524:2013.

[12] A method for producing a conductive paste, comprising the method for producing the conductive paste as described in [1] or [11], wherein the mixture is dispersed and filtered through a filter with a pore diameter of 1 μm or more and 25 μm.

In addition, it is more preferable that the present invention contains the following constitutions.

[15] A conductive coating film for laser etching, characterized by at least containing a reaction hardened product composed of a phenoxy resin having a number average molecular weight of 3,000 to 100,000 and a blocked isocyanate, and a median diameter D50 of 0.5 μm or more The silver powder, and the surface roughness Ra of the coating film is 0.4 or less.

[16] The method for producing a conductive paste according to [8], wherein the dispersant is solid at 25° C., and the silver powder, the binder resin, the solvent, and the dispersant are mixed and dispersed at one time.

[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 uses a ^{phenoxy resin with an acid value of 20-500 eq./10 6} g as a binder, and the surface roughness Ra of the coating film formed by screen printing is 0.4 μm or less, It is a conductive paste that can form a conductive film with excellent adhesion to the substrate after the wet heat test. By adopting such a configuration, the line width and the width between lines can be made finer, and the following conductivity can be formed. Film: fine wiring required for touch panels, etc., and TFT gate electrodes, base electrodes, collector electrodes, and emitter electrodes, etc., obtained by using printed electronics.

In addition, the conductive paste of the present invention is a conductive paste characterized by the following: an organic component containing a thermoplastic and/or thermosetting resin, silver powder, and an organic solvent, the organic component contains a binder resin, and a mesh is used. The surface roughness Ra of the coating film formed by lithography is 0.4 μm or less, and by adopting such a structure, a conductive film suitable for a TFT base electrode can be formed.

Furthermore, in the present invention, the paste is preferably mixed and dispersed by a specific blending method and subjected to a filtering step to obtain a predetermined degree of dispersion. As a result, a conductive film with a smooth surface and excellent laser etching suitability can be obtained.

<<Ingredients constituting the conductive paste of the present invention>>

The conductive paste of the present invention contains an organic component containing a thermoplastic and/or thermosetting resin, silver powder, and an organic solvent, and the organic component contains a binder resin as an essential component. The organic component in the present invention refers to the entire portion after removing the inorganic component and the organic solvent in the conductive paste.

<Binder resin>

In the present invention, 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 to 500 eq./10 ^{6 g is necessary.}

The phenoxy resin in the present invention refers to 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 copolymerization type, bisphenol S type, and bisphenol A/S copolymerization type. Among them, a phenoxy resin derived from a bisphenol A type can be preferably used from the viewpoint of substrate adhesion.

Phenoxy resin of acid value in the present invention should be less than 20eq./10 ⁶ g 500eq./10 ⁶ g or less, more preferably less than 30eq./10 ⁶ g 200eq./10 ⁶ g or less. The acid value in the organic component will improve the substrate adhesion, especially the adhesion after the wet heat test, but if it is too high, the hydrolysis of the organic component will be accelerated, and the electrical conductivity and substrate adhesion may be impaired. In addition, there is also concern about adverse effects on migration resistance.

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

In the present invention, resins other than the phenoxy resin having a predetermined acid value can be blended. The type of the binder resin is not particularly limited as long as it is a thermoplastic resin, and examples include polyester resin, epoxy resin, phenoxy resin, polyamide resin, polyamide imide resin, polycarbonate resin, polyamine Formate resin, phenol resin, acrylic resin, polystyrene, styrene-acrylic resin, styrene-butadiene copolymer, polyethylene resin, polycarbonate resin, alkyd resin, styrene- Butadiene copolymer resin, polysilicon resin, Polyether resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer, polysiloxane resin, fluorine-based resin, etc. These resins can be used alone or in the form of a mixture of two or more. Preferably, one kind or a mixture of two or more kinds selected from the group consisting of polyester resin, polyurethane resin, epoxy resin, phenoxy resin, vinyl chloride resin, and cellulose 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 3,000-100,000, more preferably 8,000-50,000. If the number-average molecular weight is too low, the formed conductive film is unfavorable in terms of durability and heat-and-moisture resistance. On the other hand, if 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 remarkably deteriorated.

The glass transition temperature of the phenoxy resin in the present invention is preferably 60°C or higher, more preferably 65°C or higher. If the glass transition temperature is low, there is a concern that the reliability of the conductive film will decrease after wet heat, and the surface hardness will decrease, and the components contained in the paste will migrate to the contact object side due to viscosity. There is concern that the reliability of the conductive film will decrease. On the other hand, considering printability, adhesion, solubility, and paste viscosity, the glass transition temperature of the binder resin is preferably 150°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower.

<Silver Powder>

The shape of the silver powder used in the present invention is not particularly limited. Examples of conventionally known shapes include flake (scaly), spherical, dendritic (dendritic), and spherical primary particles described in Japanese Patent Laid-Open No. 9-306240 agglomerated. The three-dimensional shape (agglomerated shape), etc.

The median diameter (D50) of the silver powder used in the present invention is preferably 0.5 μm or more. When using the silver powder whose median diameter is 0.5 micrometer or less, there exists a possibility that a conductive path cannot be formed favorably, and electroconductivity may deteriorate. In addition, when the particle diameter becomes fine, aggregation becomes easy, and as a result, it becomes difficult to disperse, so the median diameter is preferably 0.5 μm or more.

In addition, the median diameter (D50) means the particle diameter (μm) at which the cumulative value becomes 50% of the cumulative distribution curve (volume) obtained by any measurement method. In the present invention, a laser diffraction scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., MICROTRAC HRA) is used, and the cumulative distribution curve is measured in a total reflection mode.

The tap density of the silver powder used in the present invention is preferably 2.0 g/cm ³ or more. When the tap density is low, the silver filling degree 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, and it is preferably 9.0 g/cm ³ , more preferably 7.5 g/cm ³ , and even more preferably 5.5 g/cm ^{3 .}

From the viewpoint of improving the conductivity of the formed conductive film, the content of the silver powder is preferably 400 parts by mass or more, more preferably 560 parts by mass or more, relative to 100 parts by mass of the binder resin. Moreover, from the viewpoint of making the adhesion between the silver powder and the base material good, the content of the components 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.

<Organic solvent>

The organic solvent that can be used in the present invention is not particularly limited. Considering the viewpoint of maintaining 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, and more preferably 150°C or more and less than 280°C. . The conductive paste of the present invention is generally prepared by dispersing thermoplastic resin, silver powder, organic solvent and other components added as needed by using a three-roll mill or the like, but at this time, if the boiling point of the organic solvent is too low, the If there is a solvent, it will volatilize during dispersion, and the composition ratio of the conductive paste will change. of concerns. On the other hand, if the boiling point of the organic solvent is too high, depending on the drying conditions, a large amount of the solvent may remain in the coating film, and the reliability of the coating film may be lowered.

In addition, the organic solvent that can be used in the present invention is preferably one in which the binder is soluble and the silver powder can be well dispersed therein. Specific examples include: diethylene glycol monoethyl ether acetate (EDGAC), ethylene glycol monobutyl ether acetate (BMGAC), diethylene glycol monobutyl ether acetate (BDGAC), cyclohexanone , toluene, isophorone, gamma-butyrolactone, benzyl alcohol, SOLVESSO 100, 150, 200 from Exxon Chemicals, propylene glycol monomethyl ether acetate, adipic acid, succinic acid, and dimethyl glutaric acid Mixtures of esters (such as DBE made by DuPont), terpineol, etc. Among them, considering the excellent solubility of the binder resin, moderate solvent volatility during continuous printing, and for the use of screen printing methods, etc. From the viewpoint of good printability, EDGAC, BMGAC, BDGAC and their mixed solvents are suitable.

The content of the organic solvent is preferably not less than 5 parts by weight and not more than 40 parts by weight, more preferably not less than 10 parts by weight but not more than 35 parts by weight, relative to 100 parts by weight of the total weight of the paste. If the content of the organic solvent is too high, the viscosity of the paste becomes too low, and it tends to sag during fine line printing. On the other hand, when the content of the organic solvent is too low, the viscosity as a paste may become extremely high, and when forming a conductive film, for example, screen printability may be remarkably lowered.

A carbon-based filler can be added to the conductive paste of the present invention. Examples thereof include carbon-based fillers such as carbon black, graphite powder, and Ketchen 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, relative to 100 parts by weight of the silver powder.

The conductive paste of the present invention may contain the following inorganic substances. For inorganic substances, silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, carbide Various carbides such as chromium, molybdenum carbide, calcium carbide, diamond-like carbon; various nitrides such as boron nitride, titanium nitride, zirconium nitride; various borides such as zirconium boride; titanium oxide (titania) ), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silicon dioxide, fumed silicon dioxide (such as AEROSIL made by NIPPON AEROSIL), colloidal silicon dioxide and other oxides; calcium titanate, titanic acid Various titanate compounds such as magnesium and strontium titanate; sulfides such as molybdenum disulfide; various fluorides such as magnesium fluoride and carbon fluoride; aluminum stearate, calcium stearate, zinc stearate, magnesium stearate, etc. Various metal soaps; others such as talc, bentonite, talc, calcium carbonate, bentonite, kaolin, glass fiber, mica, etc. Addition of these inorganic substances may improve printability and heat resistance, as well as mechanical properties and long-term durability. Among them, in the conductive paste of the present invention, from the viewpoint of imparting durability, printability, and especially screen printability, fumed silica is preferably added.

The conductive paste of the present invention can be blended with a dispersant, a surface modifier, a defoaming agent, and a rheology control agent as additives. In addition, carbodiimide, epoxide and the like may be appropriately blended. They can be used individually or in combination. By adding these additives to the paste, the rheology of the paste may be changed and the surface smoothness may be improved.

Examples of dispersants include Disperbyk-2155, etc., and more include monocarboxylic acids such as lauric acid, myristic acid, palmitic acid, heptadelic acid, and stearic acid; terephthalic acid, isophthalic acid, Aromatic dicarboxylic acids such as phthalic acid and 2,6-naphthalenedicarboxylic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, azelaic acid Dicarboxylic acids such as acid; dibasic acids with 12 to 28 carbon atoms such as maleic acid and dimer acid; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2- Cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, dicarboxyhydrobisphenol A, dicarboxyhydrogen Alicyclic dicarboxylic acids such as bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalene dicarboxylic acid, and tricyclodecane dicarboxylic acid; hydroxycarboxylic acids such as hydroxybenzoic acid and lactic acid. Ternary such as trimellitic anhydride and pyromellitic anhydride can also be mentioned. The above carboxylic acids; unsaturated dicarboxylic acids such as fumaric acid; carboxylic acid diols such as dimethylol butyric acid and dimethylol propionic acid.

In the present invention, aliphatic monocarboxylic acid and aliphatic dicarboxylic acid, which are solid at 25°C, are preferably used as dispersants. Specifically, lauric acid, myristic acid, palmitic acid, heptadecanoic acid, stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylate can be exemplified. Acid, azelaic acid and other dicarboxylic acids; maleic acid, etc.

Further, in the present invention, a compound having a melting point at 60°C to 150°C among these solid fatty acids is preferably used as a dispersant. The solvent will volatilize under the temperature conditions when the paste is hardened, and the dispersant will be precipitated at the same time. At the same time, it will liquefy because it reaches the melting point, and has the effect of smoothing the hardened film of the paste.

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

<hardener>

In the conductive paste of the present invention, a hardener capable of reacting with the binder resin may be blended to such an extent that the effect of the present invention is not impaired. By blending the curing agent, the curing temperature may increase and the load on the production step may increase, but it is expected to improve the moisture and heat resistance of the coating film by crosslinking by the heat generated by the drying of the coating film.

The type of the hardener capable of reacting with the binder resin of the present invention is not limited, but in consideration of adhesion, bending resistance, hardenability, etc., isocyanate compounds and/or epoxy resins are particularly preferred. Moreover, as for the isocyanate compound, if the isocyanate group is blocked, the storage stability will be improved and it is preferable. Examples of curing agents other than isocyanate compounds include methylated melamine, butylated Amine resins such as melamine, benzoguanamine, and urea resins; known compounds such as acid anhydrides, imidazoles, and phenol resins. Among these hardeners, a known catalyst or accelerator selected according to the type may be used in combination. As far as the blending amount of the hardener is concerned, it is blended within an extent that does not impair the effect of the present invention, and is not particularly limited, but is preferably 0.5 to 50 parts by mass relative to 100 parts by mass of the binder resin 1-30 mass parts is more preferable, and 2-20 mass parts is more preferable.

Examples of isocyanate compounds that can be blended into the conductive paste of the present invention include aromatic or aliphatic diisocyanates, polyisocyanates having a valence of 3 or more, and the like. Can. For example, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; hydrogenated diphenylmethane Alicyclic diisocyanates such as diisocyanates, hydrogenated xylylene diisocyanates, dimer acid diisocyanates, isophorone diisocyanates, etc.; or trimers of the above-mentioned isocyanate compounds, and excess of the above-mentioned isocyanate compounds and low-molecular-weight active hydrogen compounds Or the compounds containing isocyanate groups at the end obtained by the reaction of high molecular active hydrogen compounds, such as ethylene glycol, propylene glycol, trimethylolpropane, glycerol, sorbitol, ethylenediamine, monoethanolamine, Diethanolamine, triethanolamine, etc., the polymer active hydrogen compounds are, for example, various polyester polyols, polyether polyols, and polyamides. Moreover, as the blocking agent of isocyanate group, for example, phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol can be mentioned. , phenols such as chlorophenol; oximes such as acetoxime, methyl ethyl ketoxime, cyclohexanone oxime; alcohols such as methanol, ethanol, propanol, butanol; 2-chloroethanol, 1,3-dichloro-2-propane Halogen-substituted alcohols such as alcohols; tertiary alcohols such as tertiary butanol, tertiary pentanol; Lactamides such as amines, other active methylene compounds such as aromatic amines, imines, acetone acetone, acetoacetate, ethyl malonate, etc.; thiols, imines class, imidazoles, ureas, Diaryl compounds, sodium bisulfite, etc. Among them, oximes, imidazoles, and amines are particularly preferred in consideration of sclerosing properties.

The epoxy compound used as a curing agent in the present invention includes, for example, bisphenol A glycidyl ether, bisphenol S glycidyl ether, novolak resin glycidyl ether, brominated bisphenol A glycidyl ether, and the like. glycidyl ether type; glycidyl ester type such as glycidyl hexahydrophthalate, glycidyl dimer acid, etc.; triglycidyl isocyanurate, or 3,4-epoxycyclohexyl Alicyclic or aliphatic epoxides such as methylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil, etc. may be used alone or in combination of two or more. Among them, from the viewpoint of curability, bisphenol A glycidyl ether is the most preferable, and among them, the molecular weight is less than 3000, and it is more preferable that it has two or more glycidyl ether groups in one molecule.

<<Physical properties sought by the conductive paste of the present invention>>

The viscosity of the conductive paste of the present invention is not particularly limited, and may be appropriately adjusted according to the method of forming the coating film. For example, when using screen printing to apply the conductive paste to the substrate, the viscosity of the conductive paste should be 100dPa at the printing temperature. Above s, it is 150dPa. s or more is better. The upper limit is not particularly limited, but if the viscosity is too high, the surface smoothness may decrease.

The F value of the conductive paste of the present invention is preferably 60-95%, more preferably 75-95%. The F value represents the value of the filler mass part contained in the paste relative to 100 mass parts of the total solid content, and is expressed as: F value=(filler mass part/solid content mass part)×100. The filler mass part here refers to the mass part of the conductive powder, and the solid content mass part refers to the mass part of the components other than the solvent, including all the conductive powder, organic components, other hardeners, and additives. If the F value is too low, a conductive film exhibiting good electrical conductivity cannot be obtained, and 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 tend to decrease, and it is impossible to obtain a conductive film. Avoid printability degradation. In addition, the conductive powder here means silver powder.

The conductive paste of the present invention must have a dispersion degree of 10 μm or less according to the fineness meter specified in ISO 1524:2013. If the degree of dispersion exceeds this range, abnormal protrusions on the surface of the conductive film derived from the paste will increase, and the definition of thin lines by laser etching will deteriorate.

<<The manufacturing method of the conductive paste of the present invention>>

The conductive paste of the present invention can be obtained by dispersing the organic components, silver powder, organic solvent and other components added as necessary by using a three-roll mill or the like as described above. Here, an example of a more specific production procedure is illustrated. First, the binder resin is dissolved in an organic solvent. Then, silver powder and a dispersing agent are added, and other additives are added as necessary, and dispersion is performed by a double planetary, a dissolver, a planetary mixer, or the like. Then, the conductive paste was obtained by dispersing with a three-roll mill. The conductive paste obtained in this way can be filtered as necessary. Dispersing using other dispersing machines such as bead mills, kneaders, extruders and the like does not cause any problems.

In the present invention, a dispersant that is solid at 25°C is preferably used, and the silver powder, the solvent solution of the binder resin, and the dispersant are mixed and dispersed at one time.

In the present invention, filtration is performed after the materials are mixed and dispersed. The pore size of the filter for filtering the conductive paste is not particularly limited, but it is preferably a filter with a pore size of 25 μm or less, more preferably 20 μm or less, and most preferably 15 μm or less. When a filter with a pore size exceeding 25 μm is used, undispersed matter, coarse particles, foreign matter, etc. of the conductive powder cannot be removed, resulting in short-circuiting between thin lines after etching, resulting in deterioration of yield.

On the other hand, the pore diameter is preferably 1 μm or more, and if it is set to be finer than 1 μm, depending on the particle size of the silver powder, the filtration rate will be significantly reduced, and the filter will eventually be clogged. As a result, the number of filter replacements increases and the production efficiency decreases significantly.

After the above steps, the conductive paste of the present invention with a dispersion degree of 10 μm or less obtained by the fineness meter specified in ISO 1524:2013 can be obtained.

<<The conductive film of the present invention, the conductive laminate, and their manufacturing method>>

The conductive paste of the present invention is applied or printed on a substrate to form a coating film, and then the conductive film of the present invention can be formed by volatilizing the organic solvent contained in the coating film and drying the coating film. The method of coating or printing the conductive paste on the substrate is not particularly limited, and all printing methods such as gravure printing, offset printing, letterpress printing, inkjet printing, reverse printing, and microcontact printing can be used. From the viewpoint of the simplicity of the technology and the technology widely used in the industry to form electrical circuits using conductive paste, printing by screen printing is particularly preferred.

The step of volatilizing the organic solvent is preferably carried out at normal temperature and/or under heating. When heating, the heating temperature is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher, from the viewpoint of improving the conductivity, adhesion, and surface hardness of the conductive film after drying. Furthermore, considering the heat resistance of the transparent conductive layer of the substrate and the energy saving in the production process, the heating temperature is preferably 150°C or lower, more preferably 135°C or lower, and even more preferably 130°C or lower. When a curing agent is blended in the conductive paste of the present invention, if the step of volatilizing the organic solvent is carried out under heating, the curing reaction will proceed.

The thickness of the conductive film of the present invention may be set to an appropriate thickness in accordance with the intended use. However, considering the good conductivity of the conductive film after drying, the 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, more preferably 1.2 μm or more and 10 μm or less, and is 1.6 It is more preferably not less than μm and not more than 7 μm. When the film thickness of the conductive film is too thin, there is a possibility that the desired conductivity as a circuit cannot be obtained. In addition, the thickness of the conductive film affects the line width and the line-to-line width formed by laser etching. Therefore, especially when fine wiring is required, the thickness should not be more than necessary.

The surface roughness Ra of the conductive film of the present invention must be 0.40 μm or less. If the surface roughness Ra is too high, the scattering of the laser light in the laser etching step will become obvious, and the sharpness of the thin line (straightness of the edge) will be reduced.

In this invention, the unnecessary part of the electroconductive film obtained as mentioned above is removed (laser etching) using a laser beam, and a fine wiring is obtained. 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.

The present invention can form conductive fine wiring with a line width of 100 μm or less and a line width of 100 μm or less by laser etching. In the present invention, it is desirable that the width between lines of the conductive fine wiring be 50 μm or less, and the width between lines can be set to be 4 times or less the thickness of the conductive film. Further, in the present invention, the line width of the conductive fine wiring may be 35 μm or less, and the line width may be set to be 3.5 times or less the thickness of the conductive film.

In the present invention, the thin line width obtained by laser etching is less than 100 μm. In the present invention, a line width of about 2.5 times the thickness of the conductive film can be realized. For example, when the thickness of the conductive film is adjusted to 10 μm, the smallest line can be realized. The width is 25 μm; when the thickness of the conductive film is set to 5 μm, the line width of 12.5 μm can be realized.

In the present invention, the line width obtained by laser etching is less than 100 μm. In the present invention, the minimum line width that is about 3 times the thickness of the conductive film can be achieved. For example, when the thickness of the conductive film is adjusted to 10 μm, the The minimum line width is 30 μm; when the thickness of the conductive film is set to 5 μm, the minimum line width is 15 μm.

[Example]

In order to describe the present invention in more detail, the following examples and comparative examples are given, but the present invention is not limited by the examples at all. In addition, each measurement value described in an Example and a 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 with a pore diameter of 0.5 μm to prepare a GPC measurement sample. Using tetrahydrofuran as the mobile phase, using a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation, and using a differential refractometer (RI meter) as a detector, the column temperature was 30°C and the flow rate was 1 ml/min. GPC determination of resin samples. In addition, the number average molecular weight was set as a standard polystyrene conversion value, and the part corresponding to the molecular weight less than 1000 was omitted and calculated. Shodex KF-802, 804L, and 806L manufactured by Showa Denko Co., Ltd. were used for the GPC column.

<acid value 1>

Precisely weigh 0.2 g of the sample resin and dissolve it in 20 ml of chloroform. Then, the indicator was titrated with 0.01N potassium hydroxide (ethanol solution) using a phenolphthalein solution. The unit of acid value is eq./10 ⁶ g, which is defined as the equivalent per 1 metric ton of sample.

<acid value 2>

By dissolving 0.1 g of resin in 10 ml of benzyl alcohol/chloroform (1/1 volume ratio) mixed solvent, and dissolving the resulting solution in benzyl alcohol/methanol (9/1 volume ratio) mixed solvent with sodium hydroxide 0.4 The alkaline solution obtained by g is measured by titration.

<Glass transition temperature (Tg)>

5 mg of the sample resin was put into an aluminum sample pan, sealed, and measured using a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Co., Ltd. at a heating rate of 20°C/min to 200°C. The temperature at the intersection of the extension of the baseline below the glass transition temperature and the tangent showing the greatest slope in the transition.

<paste viscosity>

The measurement of the viscosity was carried out at 20 rpm using a BH-type viscometer (manufactured by Toki Sangyo Co., Ltd.) at a sample temperature of 25°C.

<Dispersion>

The measurement is carried out with a fineness meter specified in ISO 1524:2013.

<Preparation of Conductive Laminate Test Piece 1>

A 400-mesh stainless steel screen was used to print the conductive paste on an annealed PET film with a thickness of 100 μm (LUMIRROR S manufactured by Toray Corporation) by screen printing to form an overall coating pattern with a width of 25 mm and a length of 450 mm. Then, it heated at 130 degreeC for 30 minutes with a hot air circulation type drying furnace, and was used as a conductive laminated body test piece. Moreover, the coating thickness at the time of printing was adjusted so that a dry film thickness might be 5-10 micrometers.

<Adhesion>

Using the aforementioned conductive laminate test piece 1, evaluation was performed by a peel test using SELLOTAP E (registered trademark) (manufactured by NICHIBAN) in accordance with JIS K-5400-5-6:1990. However, the number of cuts in each direction of the lattice pattern is 11, and the cutting interval is set to 1 mm. 100/100 means no peeling and good adhesion, and 0/100 means complete peeling.

<Damp heat test>

The samples were exposed to a high temperature and high humidity container adjusted to 85°C, 85% RH, and 1 atmospheric pressure for 240 hours, and were leveled in a standard state room for more than 24 hours, and then the adhesion test was performed as a damp heat test evaluation.

<specific resistance>

The sheet resistance and film thickness of the above-mentioned conductive laminate test piece 1 were measured, and the specific resistance was calculated. As for the film thickness, GAUGE STAND ST-022 (manufactured by Ono Shoki Co., Ltd.) was used, the thickness of the PET film was set as zero point, the thickness of the cured coating film was measured at five places, and the average value was used. The sheet resistance was measured for four test pieces using MILLIOHMMETER4338B (manufactured by HEWLETT PACKARD), and the average value thereof was used. In addition, the detectable range of this milliohmmeter is 1×10 ⁻² or less (Ω·cm), and ^{the specific resistance of 1×10 −2} (Ω·cm) or more exceeds the measurement limit.

<Surface Roughness>

In the conductive laminate test piece 1, the surface roughness Ra was measured using a surface roughness meter (HANDYSURF E-35B, manufactured by Tokyo Seiki Co., Ltd., calculated according to JIS-1994).

<Laser Etchability>

Using the screen printing method, on the ITO of the polyester substrate with the ITO film formed, the conductive paste was applied by screen printing into a rectangle of 2.5 × 10 cm. After printing and coating, it was dried by hot air circulation. The oven was dried at 120° C. for 30 minutes to obtain a conductive thin film. In addition, the surface roughness R of the ITO laminate was 0.3 μm. Moreover, printing conditions etc. were adjusted so that a film thickness might become 4-6 micrometers. Then, laser etching is performed on the conductive film prepared by the above method, and the line width/line width shown below is drawn, and the line width/line width is observed by a microscope at each set line width/line width and whether there is continuity and line width. The formation of fine wiring is determined by short-circuiting to confirm whether or not the formation of fine wiring has been completed.

Line width/Line width=100μm/100μm

Line width/Line width=70μm/70μm

Line width/Line width=50μm/50μm

Line width/Line width=50μm/40μm

Line width/Line width=50μm/35μm

Line width/Line width=50μm/30μm

Line width/Line width=50μm/25μm

Line width/Line width=50μm/20μm

Line width/Line width=40μm/40μm

Line width/Line width=40μm/35μm

Line width/Line width=40μm/30μm

Line width/line width=40μm/25μm

Line width/Line width=40μm/20μm

Line width/Line width=40μm/15μm

Line width/Line width=35μm/35μm

Line width/line width=35μm/30μm

Line width/line width=35μm/25μm

Line width/line width=35μm/20μm

Line width/line width=35μm/15μm

Line width/Line width=35μm/10μm

Line width/Line width=30μm/30μm

Line width/Line width=30μm/25μm

Line width/Line width=30μm/20μm

Line width/line width=30μm/15μm

Line width/Line width=30μm/10μm

Line width/line width=25μm/25μm

Line width/Line width=25μm/20μm

Line width/Line width=25μm/15μm

Line width/Line width=25μm/10μm

Line width/Line width=20μm/20μm

Line width/Line width=20μm/15μm

Line width/Line width=20μm/10μm

In addition, a YAG laser is used for the laser light, and the minimum beam diameter is adjusted to be less than half of the width between each line. In addition, whether there is wiring continuity or short circuit between lines, a tester with an applied voltage of 1.5V is used.

<Synthesis example>

<Binder resin PH001>

After 400 parts of phenoxy resin PKHC manufactured by InChem was put into a reaction vessel equipped with a stirrer, a condenser and a thermometer, 489 parts of diethylene glycol monoethyl ether acetate (EDGAC) were charged and dissolved at 85°C. Then, 1 part of trimellitic anhydride, 0.19 parts of dimethylaminopyridine as a catalyst, and 0.48 parts of diazabicycloundecene were added, and the reaction was carried out at 85° C. for 4 hours to obtain a phenoxy resin. PH001 solution.

The solid content concentration of the obtained phenoxy resin solution was 35 mass %. The resin solution obtained in this way was dripped on a polypropylene film, and it spread|stretched using the coater made of stainless steel, and the thin film of the resin solution was obtained. It was placed in a hot air dryer adjusted to 120°C for 3 hours to volatilize the solvent, and then the resin film was peeled off from the polypropylene film to obtain a dry resin film in the form of a film, which was used for acid value determination, etc.

Hereinafter, the raw materials were changed and the modification operation was carried out to obtain the acid-modified phenoxy resin shown in Table 1.

[Example 1]

2857 parts of acid-modified phenoxy resin PH001 shown in Table 1 was dissolved in EDGAC to make the solid content concentration 35% by mass (1000 parts in terms of solid content), 8361 parts of flake silver powder 1 , 100 parts of hardener 1, 59 parts of leveling agent, 34 parts of additive 1, 164 parts of EDGAC as solvent, and dispersed by 2 cooling three-roll kneaders. Then, a filter of 635 meshes (stainless steel mesh filter (pore size 20 μm)) was attached to the paste filter, and the above-mentioned paste filtration was carried out. Then, after printing the obtained conductive paste in a predetermined pattern, it was dried at 130° C. for 30 minutes to obtain a conductive film. Basic physical properties were measured using this conductive film, and then the surface smoothness was investigated. In addition, the wet heat resistance test and the fine wiring formability by laser etching were evaluated. The evaluation results are shown in Table 2.

In addition, in Table 1

Phenoxy resin 1: PKHC manufactured by InChme Number average molecular weight 21000 Tg67°C

Phenoxy resin 2: Nippon Steel & Sumitomo Metal Chemical Co., Ltd. YP-70 Number average molecular weight 28000 Tg60℃

Phenoxy resin 3: jER-1010 manufactured by Mitsubishi Chemical, number average molecular weight 8000 Tg55℃

Phenoxy resin 4: jER-1002 manufactured by Mitsubishi Chemical, number average molecular weight 1000 Tg54°C

(Tg: glass transition temperature).

[Examples 2 to 11] [Comparative Examples 1 to 3]

The resin and the compounding amount of the conductive paste were changed, and Examples 2 to 11 and Comparative Examples 1 to 3 were implemented. The results are shown in Table 2. In the examples, the relatively low temperature and short-time heating of the oven at 130° C.×30 minutes can obtain good physical properties of the coating film. Moreover, the adhesiveness with respect to an ITO film and the adhesiveness after a humid heat environment test were also favorable. In addition, it exhibits good fine wiring formability by laser etching.

In addition, in Table 2, binder resin RV-200: Toyobo Co., Ltd. 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 ) ³ ), Silicon dioxide: #300 manufactured by NIPPON AEROSIL Co., Ltd., Carbon Black: KETJEN ECP600JD manufactured by Lion Co., Ltd., Hardener 1: MF-K60X manufactured by Asahi-Kasei Chemicals Co., Ltd., Hardener 2: BI manufactured by Baxenden -7960, hardening catalyst: KS1260 manufactured by Kyodo Chemical Co., Ltd., leveling agent: MK CONCH of Kyōeisha Chemical Co., Ltd., dispersant 3: oxalic acid dihydrate melting point 101.5°C, dispersant 5: malonic acid melting point 135 ℃, dispersant 12: Heptadelic acid melting point 61 ℃, EDGAC: diethylene glycol monoethyl ether acetate manufactured by DAICEL (stock), BDGAC: diethylene glycol monobutyl ether acetate manufactured by DAICEL (stock).

[Example 21]

2857 parts of a solution obtained by dissolving phenoxy resin PH-1 in EDGAC to make the solid content concentration 35% by mass (1000 parts in terms of solid content), 8361 parts of flaky silver powder, and 100 parts of hardener 1. 59 parts of leveling agent, 34 parts of additive 1, 164 parts of EDGAC as solvent, dispersed by cooling three-roll kneader twice. Then, a filter of 635 meshes (stainless steel mesh filter (pore size 20 μm)) was attached to the paste filter, and the above-mentioned paste filtration was carried out. Then, after printing the obtained conductive paste into a predetermined pattern, it was dried at 130° C. for 30 minutes to obtain a conductive film. Basic physical properties were measured using this conductive film, and then the surface smoothness was investigated. The evaluation results of the paste and the paste coating film are shown in Table 3.

[Examples 22 to 53] [Comparative Examples 11 to 14]

The resin and compounding amount of the conductive paste were changed, and Examples 22 to 53 and Comparative Examples 11 to 14 were implemented. The results of blending and evaluation of the conductive paste are shown in Tables 3 to 6. In the examples, the relatively low temperature and short-time heating of an oven at 130° C.×30 minutes can obtain good physical properties of the coating film. Moreover, the adhesiveness to an ITO film was also favorable.

In addition, in Tables 3 to 6, the binder resin, the conductive powder, the additive, and the solvent were used as follows.

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: PKHC manufactured by InChem (phenoxy resin, number average molecular weight 21000, Tg=66°C, acid value 2 equivalents/10 ⁶ g)

Binder resin PH-3: PKHC modified product made by InChme (phenoxy resin, number average molecular weight 21000, Tg=67°C, acid value 105 equiv/10 ⁶ g)

Binder resin PH-4: PKHH manufactured by InChem (phenoxy resin, number average molecular weight 27000, Tg=67°C, acid value 2 equivalents/10 ⁶ g)

Binder resin PH-5: Nippon Steel & Sumitomo Metal Chemical Co., Ltd. YP-50 (phenoxy resin, number average molecular weight 27000, Tg=65°C, acid value 3 equivalents/10 ⁶ g)

Binder resin PH-6: Nippon Steel & Sumitomo Metal Chemical Co., Ltd. YP-70 (phenoxy resin, number average molecular weight 28000, Tg=60°C, acid value 1 equivalent/10 ⁶ g)

Binder resin PH-7: jER-1010 manufactured by Mitsubishi Chemical (phenoxy resin, number average molecular weight 8000, Tg=55°C, acid value 2 equivalents/10 ⁶ g)

Binder resin PH-8: jER-1002 manufactured by Mitsubishi Chemical (phenoxy resin, number average molecular weight 1000, Tg=54°C, acid value 3 equivalents/10 ⁶ g)

Binder resin PS-1: RV-200 manufactured by Toyobo (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 )

Silicon dioxide: NIPPON AEROSIL (stock) system #300

Ketjen Black (carbon black): KETJEN ECP600JD made by Lion

Hardener 1: MF-K60X manufactured by Asahi-Kasei Chemicals Co., Ltd.

Hardener 2: BI-7960 by Baxehden

Hardening catalyst: KS1260 manufactured by Kyodo Chemical Co., Ltd.

Leveling agent: Kyoeisha Chemical Co., Ltd. MK CONCH

Additive 1: MK CONCH (leveler)

Additive 2: BYK-410 (rheology control agent) manufactured by BYK Corporation

Additive 3: BYK-405 (rheology control agent) manufactured by BYK Co., Ltd.

Additive 4: jER-820 (epoxide)

Dispersant 1: Disperbyk 2155 (dispersant) manufactured by BYK Corporation,

Dispersant 2: Disperbyk 130 (dispersant) manufactured by BYK 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 acid (melting point 62.9°C)

Dispersant 12: Heptadelic acid (melting point 61°C),

Dispersant 13: Stearic acid (melting point 69.6°C)

EDGAC: Diethylene glycol monoethyl ether acetate manufactured by DAICEL Co., Ltd.

BDGAC: Diethylene glycol monobutyl ether acetate manufactured by DAICEL Co., Ltd.

In addition, binder resin PH-3 was produced by the following operation.

<Binder resin PH-3>

After 400 parts of phenoxy resin PKHC manufactured by InChem was put into a reaction vessel equipped with a stirrer, a condenser and a thermometer, 489 parts of diethylene glycol monoethyl ether acetate (EDGAC) were charged and dissolved at 85°C. Then, 3 parts of trimellitic anhydride, 0.19 parts of dimethylaminopyridine as a catalyst, and 0.48 parts of diazabicycloundecene were added and reacted at 85°C for 4 hours to obtain a phenoxy resin PH-3 solution. The solid content concentration of the obtained phenoxy resin solution was 35 mass %. The resin solution obtained in this way was dripped on a polypropylene film, and it extended|stretched using the coater made of stainless steel, and the thin film of the resin solution was obtained. This was left to stand in a hot air dryer adjusted to 120° C. for 3 hours to evaporate the solvent, and then the resin film was peeled off from the polypropylene film to obtain a dry resin film in the form of a film, which was used for various measurements.

[industrial applicability]

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 good laser etching properties, and can be effectively used by combining with a conductive thin film such as ITO do It is a component for input and output interfaces such as touch panels. Moreover, it can be suitably used for the wiring layer of printed TFT etc. which require fine wiring.

Claims (6)

A conductive paste comprising at least a binder resin composed of thermoplastic and/or thermosetting resin, silver powder, and an organic solvent, characterized in that: the median diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less, and the adhesive The agent resin contains more than 60% by weight of phenoxy resin with a number average molecular weight of 3,000~100,000 and an acid value of 20~500eq./10 ⁶ g. The degree of dispersion obtained by using the fineness specified in ISO 1524:2013 is 10μm or less. A method for producing a conductive film, comprising applying the conductive paste as claimed in claim 1 to a polymer film on which an inorganic thin film layer having a surface roughness of 0.1 μm or less has been formed, And it dried and hardened, and obtained the electroconductive film whose surface roughness Ra is 0.4 micrometer or less. A conductive paste, comprising at least a binder resin composed of thermoplastic and/or thermosetting resin, silver powder, and an organic solvent, characterized in that: the median diameter D50 of the silver powder is 0.5 μm or more and 5 μm or less, and the silver powder the tap density (tap density) of 2.0g / cm ³ or more, the binder resin contains 60 wt% or more of the number average molecular weight of a phenoxy resin of from 3,000 to 100,000, and in conformity with ISO 1524: 2013 of a predetermined degree of fine The degree of dispersion measured by Grind Gage was 10 μm or less. A method for producing a conductive paste, which is a method for producing the conductive paste as claimed in item 3 of the scope of the patent application, characterized in that: after using a three-roll mill to mix and disperse the following components, a diameter of 1 μm or more and 25 μm is obtained. The following filters are used for filtration, and the composition contains at least: silver powder with a median 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 number average molecular weight of 3,000~ 60% by weight or more. 100,000 Binder resin for phenoxy resin; solvent; and dispersant. A method for producing a conductive film, comprising screen-printing the conductive paste obtained by the method for producing a conductive paste as claimed in claim 4 on a surface formed with a surface roughness of 0.1 μm or less The polymer film of the inorganic thin film layer is dried and hardened to obtain a conductive film with a surface roughness Ra of 0.4 μm or less. A method for producing conductive fine wiring, characterized by: removing unnecessary parts of a conductive film obtained by the method for producing a conductive film as claimed in claim 5 of the patented scope by laser light to obtain surface roughness Conductive fine wiring with Ra of 0.4 μm or less, a line width of 100 μm or less, and a line-to-line width of 100 μm or less.