KR20160111944A - Conductive paste for laser etching, conductive thin film and conductive laminate - Google Patents

Abstract

It is an object of the present invention to provide a high-density electrode circuit wiring having an L / S of 50/50 占 퐉 or less, which is deemed difficult to cope with by a conventional screen printing method, and is suitable for laser etching processing which can be manufactured at a low cost and a low environmental load And a conductive paste for laser etching that can be used for an Ag nanowire substrate.
The above object is achieved by a conductive paste for laser etching comprising an organic component (A), a silver powder (B) and an organic solvent (C) each comprising a thermoplastic and / or thermosetting resin, The conductive paste for laser etching is characterized in that it contains a phenoxy resin as a).

Description

TECHNICAL FIELD [0001] The present invention relates to a conductive paste for laser etching, an electroconductive thin film, and an electroconductive laminate,

The present invention relates to a method of producing a conductive pattern capable of producing a conductive pattern having a high arrangement density in the planar direction and a conductive paste suitably applicable to the method. The conductive pattern of the present invention can be typically used for an electrode circuit wiring of a transparent touch panel.

2. Description of the Related Art In recent years, electronic devices equipped with a transparent touch panel represented by a cellular phone, a notebook computer, an electronic book, and the like have been rapidly advanced and miniaturized. In order to achieve high performance and miniaturization of these electronic devices, in addition to miniaturization, high performance, and integration of the electronic components to be mounted, it is required to increase the density of the electrode circuit wiring connecting these electronic components. In addition to a resistive film method in which the number of electrode circuit wiring lines is reduced as a method of a transparent touch panel, the spread of a capacitance method in which the number of electrode circuit wiring lines is dramatically increased has recently been rapidly progressing. From this point of view, have. In addition, there is a demand to make the frame portion where the electrode circuit wiring is arranged to be narrower in order to make the display screen larger, and also in the product design, and from this point of view also, high density of the electrode circuit wiring is required. In order to satisfy the above requirement, there is a demand for a technique capable of high-density arrangement of the electrode circuit wiring of the prior art.

The arrangement density of the electrode circuit wiring of the frame portion of the resistive film type transparent touch panel is preferably not less than about 200 占 퐉 (hereinafter referred to as "L / S = 200/200 占 퐉" And it has been conventionally done to form the conductive paste by screen printing. In the capacitive touch panel, the L / S requirement is about 100/100 μm or less, and furthermore, the L / S is required to be 50/50 μm or less. Technology has become a difficult situation to cope with.

As an example of a candidate electrode circuit wiring forming technique for screen printing, a photolithography method can be used. By using the photolithography method, it is also possible to form fine lines having an L / S of 50/50 μm or less. However, the photolithography method has a problem. The most typical example of the photolithography method is a method using a photosensitive resist. In general, a photosensitive resist is applied to a copper foil portion of a surface substrate on which a copper foil layer is formed, and a desired pattern is formed by a photomask, And development of the photosensitive resist is performed. Thereafter, the copper foil portions other than the desired pattern are dissolved and removed with a chemical to form a thin line pattern of the copper foil. For this reason, the environmental burden due to the waste liquid treatment is large, and the process is troublesome, and there are many problems including the viewpoint of production efficiency and cost.

In the photolithography method, there is also a method in which a photosensitive resist is not used. For example, in Patent Documents 1 and 2, a dry film (coating film) is formed by using a conductive paste, And then irradiating the irradiated portion to the substrate to develop and remove the unirradiated portion to form a desired pattern. With this method, the process is simplified as much as the conventional photolithography method in which the photosensitive resist is not used. However, since the development process of the wet process is required in the same manner as the photolithography method using the conventionally known photosensitive resist, And since a glass frit or a nano-sized silver powder is used as a component of the conductive paste, a high temperature of 400 DEG C or more is required in the firing step and a large amount of energy is required. However, Which is a problem in that it is limited to endure the sintering process at a high temperature. Further, it is difficult to say that the process is troublesome and is also inappropriate in terms of production efficiency.

As a candidate for the electrode circuit wiring forming technique to replace screen printing, the laser etching method disclosed in the patent document 3 has recently attracted attention due to the above situation. By using the laser etching method, it is also possible to form a fine line having an L / S of 50/50 μm or less. The laser etching method refers to a method in which a layer containing a binder resin and a conductive powder (hereinafter referred to as a conductive thin film) is formed on an insulating substrate and a part of the layer is removed on an insulating substrate by laser light irradiation. However, since removal of the conductive thin film by the laser light irradiation generates a large amount of heat, the conductive thin film and the substrate are thermally deteriorated, and as a result, there is a fear that the adhesion of the substrate and the electrical characteristics which are indispensable to the conductive thin film are impaired.

Recently, there have been many requests to apply this laser etching method to Ag nanowire substrate. The Ag nanowire base material can be reduced in resistance as compared with the conventional ITO base material, and the size of the touch panel can be increased. It also has an advantage of being suitable for the roll to roll method which is excellent in flexibility and has merit in mass production. However, the contact resistance of the Ag nanowire layer with the conductive thin film tends to be higher with respect to the ITO layer, so that the conductive paste applicable to the ITO film can not always be applied.

Patent Document 1: JP-A-2010-237573 Patent Document 2: JP-A-2011-181338 Patent Document 3: Japanese Patent Application No. 2012-161485

It is an object of the present invention to provide a manufacturing method capable of producing a high-density electrode circuit wiring without any problem even when the laser etching method is applied to an Ag nanowire substrate. Another object of the present invention is to provide a conductive paste which can be suitably used in such a production method.

The present inventors have intensively studied a manufacturing method of disposing the electrode circuit wiring at a high density in the plane direction. As a result, they have found a conductive paste suitable for forming a conductive thin film having laser etching suitability and Ag nanowire substrate suitability. That is, the present invention has the following constitution.

1. A conductive paste for laser etching comprising an organic component (A), a silver powder (B) and an organic solvent (C) comprising a thermoplastic and / or thermosetting resin, wherein the binder resin (a) A conductive paste for laser etching processing, which comprises a phenoxy resin.

2. The conductive paste for laser etching according to item 1, wherein the binder resin (a) contains 60% by weight or more of a phenoxy resin.

3. The conductive paste for laser etching according to 1 or 2, wherein the binder resin (a) has a number average molecular weight of 3,000 to 100,000.

4. The conductive paste is filtered. Wherein the conductive paste is a conductive paste for laser etching.

5. The above items 1-4. Wherein the conductive thin film is formed of an electroconductive paste for laser etching.

6. The conductive laminate according to item 5, wherein the conductive thin film and the substrate are laminated.

7. The conductive laminate according to 6, wherein the substrate has a transparent conductive layer.

8. An electric circuit using the conductive thin film as described in 5 above, or the conductive laminate as described in 6 or 7.

9. An electric circuit having a wiring portion formed by irradiating a part of the conductive thin film described in 5 above with a laser beam selected from a carbon dioxide gas laser, a YAG laser, a fiber laser and a semiconductor laser to remove a part of the conductive thin film.

10. The electric circuit according to 9, wherein the conductive thin film is formed on the transparent conductive layer.

11. The method of any one of items 8 to 10, Wherein the touch panel includes an electric circuit according to any one of claims 1 to 6.

The conductive paste of the present invention is a conductive paste containing an organic component (A), a silver powder (B) and an organic solvent (C) each comprising a thermoplastic and / or thermosetting resin, (a), and a phenoxy resin is contained in (a). By adopting such a constitution, it is possible to form a conductive thin film excellent in laser etching process suitability and Ag nanowire substrate suitability have. Here, the laser etching processing suitability is excellent when at least a part of the conductive thin film is removed from the substrate by laser etching to form thin lines of L / S = 30/30 탆, 1) ensuring conduction between both ends of the fine lines 4) Good adhesion to the Ag nanowire substrate and the ITO substrate after the initial and wet heat load, even after the laser etching, and 4) Good adhesion between the adjacent wires. Indicates satisfaction. Further, when the Ag nanowire substrate suitability is excellent, the contact resistance to the Ag nanowire base material is good and the change in the contact resistance value after the wet heat environment load is small. By filtering the conductive paste which is an embodiment of the present invention, it is possible to remove coarse grains by applying shear to the agglomerated silver powder, thereby exhibiting the effect of improving the etching defectiveness.

Fig. 1 is a schematic diagram showing a pattern for irradiating a laser beam to a test piece for evaluating the suitability for laser etching machining used in Examples and Comparative Examples of the present invention. Fig. The white portion is irradiated with laser light to remove the conductive thin film formed on the substrate. No laser light is irradiated to the halftone dot portion. The unit of dimension display in the drawing is mm.
2 is a schematic view of a test piece for evaluation of contact resistance used in Examples and Comparative Examples of the present invention. The white part is an Ag nanowire base or an ITO base, and the halftone part is an Ag paste. The unit of dimension display in the drawing is mm.

≪ Components constituting the conductive paste of the present invention >

The conductive paste according to the present invention contains an organic component (A), a silver powder (B) and an organic solvent (C) each containing a thermoplastic and / or thermosetting component as essential components and a binder resin (a), and (a) contains a phenoxy resin as an essential component.

The organic component (A) in the present invention refers to all parts except the inorganic component in the conductive paste and the organic solvent (C).

≪ Binder resin (a) >

The kind of the binder resin (a) is not particularly limited as long as it is a thermoplastic resin, and examples thereof include a polyester resin, an epoxy resin, a phenoxy resin, a polyamide resin, a polyamideimide resin, a polycarbonate resin, a polyurethane resin, A styrene-butadiene copolymer, a polystyrene, a styrene-acrylic resin, a styrene-butadiene copolymer, a phenol resin, a polyethylene resin, a polycarbonate resin, a phenol resin, an alkyd resin, , A vinyl chloride-vinyl acetate copolymer resin, an ethylene-vinyl acetate copolymer resin, polystyrene, a silicone resin, and a fluorine resin. These resins can be used singly or as a mixture of two or more kinds. It is preferably 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 fibrin derivative resin. Among these resins, a phenoxy resin is preferable as the binder resin (a) and essential as a component. The reason why the phenoxy resin is preferable is that it has excellent laser etching aptitude, excellent heat resistance, and high circuit reliability after laser etching.

As one of the advantages of using the phenoxy resin as an essential component as the binder resin (a) in the present invention, as compared with other binder resins, the conductive paste using the phenoxy resin has a contact resistance This is a good point. It is considered that this is due to the fact that OH groups rich in phenoxy resin interact with the Ag nanowire layer.

In the present invention, the phenoxy resin is a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin and has a molecular weight of 3,000 to 100,000. Examples of the phenoxy resin used as the binder resin (a) in the present invention include bisphenol A type, bisphenol A / F copolymerization type, bisphenol S type, and bisphenol A / S copolymerization type. Among them, bisphenol A type is preferable from the viewpoint of substrate adhesion.

The number average molecular weight of the binder resin (a) 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 from the viewpoints of the durability and moisture resistance of the formed conductive thin film. On the other hand, if the number-average molecular weight is too high, the cohesive force of the resin increases and the durability as the conductive thin film improves, but the suitability for laser etching is remarkably deteriorated.

The glass transition temperature of the binder resin (a) in the present invention is preferably 60 占 폚 or higher, and more preferably 65 占 폚 or higher. If the glass transition temperature is low, the suitability for laser etching may be improved. However, there is a fear that the reliability after wet heat as a conductive thin film is lowered, and also the surface hardness is lowered and tackiness is caused, There is a fear that the reliability of the conductive thin film is deteriorated. The glass transition temperature of the binder resin (a) is preferably 150 占 폚 or lower, more preferably 120 占 폚 or lower, more preferably 100 占 폚 or lower, in view of printability, adhesiveness, solubility, paste viscosity and laser etching processability Do.

That the acid value of the organic component (A) in the present invention is not particularly limited, and 20 equivalents / 10 ⁶ g or more to 500 eq / 10 ⁶ g or less or less is preferable, and 50 equivalents / 10 ⁶ g 400 eq / 10 ⁶ g or more More preferable. The acid value in the organic component (A) improves the adhesion of the base material, but if too high, the hydrolysis of the organic component is promoted, which may deteriorate the conductivity and the substrate adhesion.

<Silver powder>

The silver powder used in the present invention is silver alone and does not include silver-coated alloy fine particles such as silver-coated copper alloy powder, which is a copper powder that is plated or alloyed with silver.

The shape of the silver powder (B) used in the present invention is not particularly limited. Examples of conventionally known shapes include flake type (spherical type), spherical type, twig type (dendrite type), and spherical primary particles described in Japanese Patent Application Laid-Open No. 9-306240 (Cohesive type), and the like. Among these, spherical, coagulated, and flake types are preferably used from the viewpoint of laser etching property.

The center diameter (D50) of the silver powder (B) used in the present invention is preferably 4 mu m or less. By using the silver powder (B) having a center diameter of 4 탆 or less, the fine line shape of the laser-etched portion tends to be good. In the case of using a silver powder having a center diameter larger than 4 탆, the fine line shape after the laser etching process is deteriorated, and as a result, the fine lines may contact each other and short circuit may occur. Further, there is a possibility that the conductive thin film, once peeled off and removed by laser etching, may be attached again to the machining area. Although the lower limit of the central diameter of the silver (B) powder is not particularly limited, it is preferable that the center diameter is 80 nm or more because the powder tends to flocculate when the particle size becomes finer and the particle size becomes finer and the dispersion becomes difficult. When the center diameter is smaller than 80 nm, the cohesive force is increased and the laser etching processability is deteriorated.

On the other hand, the center diameter (D50) refers to the particle diameter (占 퐉) at which the cumulative value is 50% in the cumulative distribution curve (volume) obtained by a certain measuring method. In the present invention, the cumulative distribution curve is measured in a total reflection mode using a laser diffraction scattering type particle size distribution measuring apparatus (MICROTRAC HRA, manufactured by Nikkiso Co., Ltd.).

The content of the silver (B) powder is preferably 400 parts by mass or more, and more preferably 560 parts by mass or more, based on 100 parts by mass of the binder resin (a) from the viewpoint of good conductivity of the formed conductive thin film. The content of the component (B) is preferably 1,900 parts by mass or less, more preferably 1,230 parts by mass or less, based on 100 parts by mass of the thermoplastic resin (A) from the viewpoint of good adhesion to the substrate.

&Lt; Organic solvent (C) >

The organic solvent (C) usable 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 organic solvent (C) preferably has a boiling point of 100 캜 or more and less than 300 캜, Is higher than 150 deg. C and lower than 280 deg. The conductive paste of the present invention is typically produced by dispersing a thermoplastic resin (A), a silver powder (B), an organic solvent (C), and other components as necessary with a three roll mill or the like. If the boiling point is too low, the solvent may volatilize during dispersion, and the composition 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.

As the organic solvent (C) usable in the present invention, it is preferable that the binder resin (a) is soluble and the silver powder (B) can be well dispersed. Specific examples include ethyldiglycol acetate (EDGAC), butyl glycol acetate (BMGAC), butyldiglycol acetate (BDGAC), cyclohexanone, toluene, isophorone,? -Butyrolactone, benzyl alcohol, A mixture of dimethyl ester of propylene glycol monomethyl ether acetate, adipic acid, succinic acid and glutaric acid (for example, DBE, manufactured by DuPont), terpineol, etc., Of these, EDGAC, BMGAC, BDGAC, and mixed solvents thereof are preferable from the viewpoints of excellent solubility of the binder resin (a), solvent volatility during continuous printing, and good suitability for printing by a screen printing method or the like .

The content of the organic solvent (C) is preferably 5 parts by weight or more and 40 parts by weight or less, more preferably 10 parts by weight or more and 35 parts by weight or less, based on 100 parts by weight of the total weight of the paste. If the content of the organic solvent (C) is too high, the viscosity of the paste becomes too low and it tends to cause sagging during thin line printing. On the other hand, if the content of the organic solvent (C) is too low, the viscosity as a paste becomes very high, so that the screen printing property when forming the conductive thin film is markedly lowered, The workability may be lowered.

&Lt; Laser light absorbing agent (D) >

The conductive paste of the present invention may be blended with the laser ray absorbent (D). Here, the laser light absorbent (D) refers to an additive having a strong absorption at the wavelength of the laser light, and the laser light absorbent (D) itself may be conductive or nonconductive. For example, when a YAG laser having a fundamental wave of 1064 nm is used as a light source, a dye and / or pigment having strong absorption at a wavelength of 1064 nm can be used as the laser light absorbent (D). By blending the laser ray absorbent (D), the conductive thin film of the present invention absorbs the laser light with high efficiency and promotes volatilization and thermal decomposition of the binder resin (a) due to heat generation, and as a result, suitability for laser etching is improved.

Among the laser ray absorbent (D) usable in the present invention, carbon-based fillers such as carbon black and graphite powder are examples of those having conductivity. Although the carbon-based filler has an effect of improving the conductivity of the conductive thin film of the present invention, carbon black has an absorption wavelength in the vicinity of 1060 nm. Therefore, a laser beam having a wavelength of 1064 nm such as a YAG laser or a fiber laser Since the electroconductive thin film absorbs the laser light with high efficiency, the sensitivity to the laser light irradiation is increased, so that good laser etching processing suitability is obtained even when the scanning speed of laser irradiation is increased and / or when the laser light source is low output power Can be expected. 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, per 100 parts by weight of the silver powder (B). When the compounding ratio of the carbon-based filler is too low, the effect of increasing the conductivity and raising the sensitivity to laser light irradiation are small. On the other hand, when the compounding ratio of the carbon-based filler is too high, the conductivity of the conductive thin film tends to deteriorate, and the resin adsorbs to the void portion of the carbon, thereby deteriorating the adhesiveness with the substrate .

Among the laser ray absorbent (D) usable in the present invention, examples of non-conductive ones include conventionally known dyes, pigments and infrared ray absorbents. More specifically, examples of the azo dye include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, A yellow pigment, an orange pigment, a brown pigment, a red pigment, a purple pigment, a blue pigment, a green pigment, a fluorescent pigment, a metal powder pigment, and other polymer-bonded pigments . Specific examples of the pigments include azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, Quinophthalone pigments, dye lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments and inorganic pigments can be used. Examples of the infrared absorber include NIR-IM1, an infrared absorber of the diimonium salt type, and NIR-AM1 (all manufactured by Nagase Chemtech), of the aminium salt type. The non-conductive laser ray absorbent (D) is preferably contained in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight. When the blending ratio of the non-conductive laser ray absorbent (D) is excessively low, the effect of raising the sensitivity to laser light irradiation is small. When the blending ratio of the nonconductive laser ray absorbent (D) is too high, the conductivity of the conductive thin film may be lowered, and the color tone of the laser ray absorbent becomes remarkable, which is not preferable depending on the use.

To the conductive paste of the present invention, the following inorganic materials may be added. Examples of the inorganic substance include various carbides such as silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide and diamond carbon lactam; Various nitrides such as boron nitride, titanium nitride, and zirconium nitride, and various borides such as zirconium boride; Various oxides such as titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica, fumed silica (for example, AEROSIL manufactured by Nippon Aerosil), and colloidal silica ; Various titanic acid compounds such as calcium titanate, magnesium titanate, and strontium titanate; Sulfides such as molybdenum disulfide; Various fluorides such as magnesium fluoride and carbon fluoride; Various metal soaps such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate; In addition, talc, bentonite, talc, calcium carbonate, kaolin, glass fiber, mica and the like can be used. By adding these inorganic substances, it is possible to improve the printability and heat resistance, and furthermore, to improve the mechanical properties and the durability for a long period of time. Among them, in the conductive paste of the present invention, fumed silica is preferable from the viewpoint of imparting durability, printability, particularly screen printing suitability.

To the conductive paste of the present invention, the following acid components may be added. Examples of the acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid and 2,6-naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, Aliphatic dicarboxylic acids such as dicarboxylic acid and dimer acid; dicarboxylic acids having 12 to 28 carbon atoms such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid Acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenation Naphthalene dicarboxylic acid, tricyclodecanedicarboxylic acid and other alicyclic dicarboxylic acids, and hydroxycarboxylic acids such as hydroxybenzoic acid and lactic acid. Further, carboxylic acid diols having three or more valences such as trimellitic anhydride and pyromellitic anhydride and unsaturated dicarboxylic acids such as fumaric acid, dimethylolbutanoic acid, and dimethylolpropionic acid can be added.

The conductive paste of the present invention may further contain a tack plasticizer, a defoaming agent, a flame retardant, a tackifier, a hydrolysis inhibitor, a leveling agent, a plasticizer, an antioxidant, an ultraviolet absorber, a pigment and a dye. Further, as the resin decomposition inhibitor, carbodiimide, epoxy and the like may be appropriately compounded. These can be used alone or in combination.

&Lt; Curing agent (E) >

The conductive paste of the present invention may be mixed with a curing agent capable of reacting with the binder resin (a) to such an extent as not to impair the effect of the present invention. The incorporation of the curing agent increases the curing temperature and increases the load on the production process. However, it is expected that the heat and humidity resistance of the coating film can be improved by crosslinking caused by heat generated during drying of the coating film or laser etching.

The type of the curing agent capable of reacting with the binder resin (a) of the present invention is not limited, but an isocyanate compound and / or an epoxy resin are particularly preferable from the viewpoint of adhesion, flexing resistance, curability and the like. With respect to the isocyanate compound, use of an isocyanate group-blocked one is preferable because the storage stability is improved. Examples of the curing agent other than the isocyanate compound 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 may be used in combination with known catalysts or accelerators selected depending on the kind thereof. The blending amount of the curing agent is not particularly limited, but is preferably 0.5 to 50 parts by mass, more preferably 1 to 30 parts by mass, per 100 parts by mass of the binder resin (a) And more preferably 2 to 20 parts by mass.

Examples of the isocyanate compound that can be incorporated into the conductive paste of the present invention include an aromatic or aliphatic diisocyanate, a trivalent or higher polyisocyanate, and the like, and may be any of a low molecular weight compound and a high molecular weight compound. Examples thereof include aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, Alicyclic diisocyanates such as dimer acid diisocyanate and isophorone diisocyanate, or trimers of these isocyanate compounds, and an excess amount of these isocyanate compounds, such as ethylene glycol, propylene glycol, trimethylol propane, glycerin, sorbitol, ethylenediamine, mono Low molecular active hydrogen compounds such as ethanolamine, diethanolamine and triethanolamine, or various polyester polyols, polyether polyols, polymeric active hydrogen compounds of polyamides, Containing terminal isocyanate group-containing compound. Examples of the blocking agent for the isocyanate group 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; and lactames such as? -caprolactam,? -valerolactam,? -butyrolactam and? -propiolactam. In addition, aromatic amines such as aromatic amines, imides, acetylacetone, acetoacetic acid ester, malonic acid ethyl ester , Mercaptans, imines, imidazoles, ureas, diaryl compounds, sodium bisulfite, and the like. Among them, oxides, imidazoles and amines are particularly preferable in the 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 bis (bromide), hexahydrophthalic acid glycidyl Esters and dimer acid glycidyl esters, glycidyl ester types such as triglycidyl isocyanurate, 3,4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene and epoxidized soybean oil, Aliphatic epoxide and the like, and they may be used singly or in combination of two or more. Among them, bisphenol A glycidyl ether is most preferable from the viewpoint of curability, and among them, it is more preferable to have a molecular weight of less than 3000 and having two or more glycidyl ether groups in one molecule.

<< Physical properties required for the conductive paste of the present invention >>

The viscosity of the conductive paste of the present invention is not particularly limited and may be suitably adjusted according to the method of forming the 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. Although the upper limit is not particularly limited, if the viscosity is too high, the film thickness of the conductive thin film becomes excessively thick, and the suitability for laser etching may deteriorate in some cases.

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 representing the filler mass portion with respect to 100 parts by mass of the total solid content contained in the paste, and is represented by F value = (pillar mass portion / solid portion mass portion) x 100. The term "filler mass" as used herein refers to the mass part of the conductive powder, the mass of the solid component, and the mass of the component other than the solvent, and includes the conductive powder, the organic component, and other curing agents and additives. If the F value is too low, a conductive thin film exhibiting good conductivity can not be obtained. If the F value is too high, the adhesion between the conductive thin film and the base material and / or the surface hardness of the conductive thin film tends to be lowered. . Here, the conductive powder refers to the silver powder (B).

<< Manufacturing Method of Conductive Paste of the Present Invention >>

The conductive paste of the present invention can be produced by dispersing the organic component (A), the silver powder (B), the organic solvent (C), and other components as necessary, by three rolls or the like as described above. Here, an example of a more detailed production procedure is shown. The binder resin (a) is first dissolved in the organic solvent (C). Thereafter, the silver powder (B) and, if necessary, additives are added and dispersed by a double planarizer, a dissolver or a planetary mixer. Thereafter, the mixture is dispersed with a three-roll mill to obtain a conductive paste. The conductive paste thus obtained can be filtered if necessary. There is no problem even if it is dispersed by using other dispersing machine such as bead mill, kneader, extruder and the like.

The eye size as a filter for filtering the conductive paste is not particularly limited, but a filter of 25 m or less is preferable, more preferably 20 m or less, and most preferably 15 m or less. When a filter having an eye size of more than 25 mu m is used, the fine powder of conductive powder, coarse particles, foreign matter, and the like can not be removed, and a short circuit occurs between the fine lines after etching, thereby deteriorating the yield.

On the other hand, the eye size is preferably at least 1 mu m, and when it is smaller than this, the filtration speed is significantly lowered depending on the particle diameter of the silver powder, and finally the eyes of the filtration filter are clogged. As a result, the number of filter filter replacement times increases, and the production efficiency is remarkably lowered.

The material of the filter for filtering the conductive silver paste is not particularly limited such as stainless steel, nickel, polyester, nylon, PTFE (polytetrafluoroethylene), polypropylene and other metals, but stainless steel is preferable from the viewpoint of durability. There is also no restriction to increase the filtration accuracy by performing flat processing or Teflon processing on the filter surface made of these.

Conductivity is not particularly limited as to a method of filtering a paste, but a method of filtering the paste by its own weight while agitating and rotating a stirring blade made of a plastic (for example, polyoxymethylene) having excellent abrasion resistance is simple in terms of apparatus, .

The number of revolutions of the agitation is not limited as long as the filtration of the paste does not impair the production efficiency.

As these filters, PF160A, PF320A and the like manufactured by ProTech Co., Ltd. are preferable. There is no need to pressurize as an option of the apparatus or to improve the filtration efficiency by reducing the pressure.

<< Conductive Thin Film of the Present Invention, Conductive Laminate and Method for Producing the Same >>

The conductive thin film of the present invention can be formed by coating or printing a conductive paste of the present invention on a substrate to form a coating film, and subsequently volatilizing the organic solvent (C) contained in the coating film to dry the coating film. The method of applying or printing the conductive paste onto the substrate is not particularly limited, but printing by the screen printing method is preferable in view of the process being simple and the technique which is popular in the industry for forming an electric circuit by using the conductive paste. It is preferable that the conductive paste is applied or printed to a region somewhat wider than the area of the conductive thin film finally required as an electric circuit from the viewpoint of forming the electric circuit of the present invention efficiently by lowering the load of the laser etching process.

As the substrate to which the conductive paste of the present invention is applied, a material having excellent dimensional stability is preferably used. For example, a film containing a material having excellent flexibility such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate or polycarbonate. Inorganic materials such as glass can also be used as a substrate. The thickness of the base material is not particularly limited, but is preferably 50 to 350 占 퐉, more preferably 100 to 250 占 퐉 in terms of mechanical properties, shape stability, or handleability of the pattern forming material.

Further, by performing physical treatment and / or chemical treatment on the surface of the base material to which the conductive paste of the present invention is applied, the adhesion between the conductive thin film and the base material can be improved. Examples of the physical treatment method include a sand blast method, a wet blast method of spraying a liquid containing fine particles, a corona discharge treatment method, a plasma treatment method, and an ultraviolet ray or vacuum ultraviolet ray irradiation treatment method. Examples of the chemical treatment method include a strong acid treatment method, a strong alkali treatment method, an oxidant treatment method, and a coupling agent treatment method.

The substrate may have a transparent conductive layer. The conductive thin film of the present invention can be laminated on the transparent conductive layer. The material of the transparent conductive layer is not particularly limited, and examples thereof include an ITO film composed mainly of indium tin oxide and a silver nanowire film containing nano-sized linear silver. Further, the transparent conductive layer may be formed not only on the entire surface of the substrate but also partially removed from the transparent conductive layer by etching or the like.

The step of volatilizing the organic solvent (C) is preferably carried out at normal temperature and / or under heating. In the case of heating, the heating temperature is preferably 80 占 폚 or higher, more preferably 100 占 폚 or higher, and even more preferably 110 占 폚 or higher, since conductivity, adhesion, and surface hardness of the conductive thin film after drying become satisfactory. The heating temperature is preferably 150 占 폚 or lower, more preferably 135 占 폚 or lower, and even more preferably 130 占 폚 or lower, from the viewpoints of heat resistance of the underlying transparent conductive layer and energy saving in the production process. When the conductive paste of the present invention contains the curing agent, the curing reaction proceeds when the step of volatilizing the organic solvent (C) is carried out under heating.

The thickness of the conductive thin film of the present invention may be set to an appropriate thickness depending on the intended use. The thickness of the conductive thin film is preferably in the range of 3 탆 to 30 탆, more preferably in the range of 4 탆 to 20 탆, and more preferably in the range of 20 탆 to 20 탆, from the viewpoints of good conductivity of the conductive thin film after drying and good laser etching workability. Mu m or less, more preferably 4 mu m or more and 10 mu m or less. If the thickness of the conductive thin film is too thin, there is a possibility that desired conductivity as a circuit may not be obtained. If the film thickness is excessively large, a laser irradiation amount required for laser etching processing is excessively required, and the substrate may be damaged. In addition, if the variation of the film thickness is large, the ease of etching of the conductive thin film varies, and there is a tendency that short-circuit between lines due to insufficient etching or disconnection due to excessive etching tends to occur. Therefore, it is preferable that the fluctuation of the film thickness is small.

The surface roughness Ra of the conductive thin film of the present invention is preferably 0.7 占 퐉 or less, and more preferably 0.5 占 퐉 or less. If the surface roughness Ra is too high, the etching end of the conductive thin film tends to be roughly formed, and there is a possibility that short-circuit between lines or disconnection due to excessive etching may occur easily. The surface roughness Ra is strongly influenced by the paste composition (in particular, the organic component species and the silver powder species), the paste viscosity, and the screen printing conditions. Therefore, it is necessary to control them appropriately.

<< Electric Circuit of the Present Invention and Method of Manufacturing the Same >>

An electric circuit of the present invention is an electric circuit having a wiring portion formed by irradiating laser light to at least a part of a conductive thin film formed on a substrate by the conductive paste of the present invention and removing a part of the conductive layer on a substrate. Unlike the photolithography method, the pattern formation process can be a dry process, and a waste solution containing a metal component is not generated. Therefore, a process for forming an electric circuit is not required, and it is said to be an environmentally friendly process . Further, since it is simple in terms of process, it is possible to inhibit investment in the manufacturing facility, and maintenance after the operation of the manufacturing facility is easy. On the other hand, the method of forming the conductive thin film on the substrate by the conductive paste is not particularly limited, but can be performed by printing or painting.

The method of irradiating the laser beam is not particularly limited, but a laser etching processing apparatus which has recently become popular can be used, or one having a further improved dimensional accuracy can be used. Since the laser etching processing apparatus can use data produced by image processing application software such as CAD as it is for laser processing, it is very easy to switch the manufacturing pattern. This is one of the advantages of pattern formation by a screen printing method which has been conventionally performed.

At the site where the laser beam is irradiated and absorbed, the energy of the laser beam is converted into heat, and thermal decomposition and / or volatilization occurs due to the temperature rise, and the irradiated portion is peeled and removed. In order for the portion of the conductive thin film of the present invention irradiated with laser light to be efficiently removed from the substrate, it is preferable that the conductive thin film of the present invention has strong absorption at the wavelength of the irradiated laser light. Therefore, as the laser species, it is preferable to select a laser species having energy in a wavelength region in which one component constituting the conductive thin film of the present invention has strong absorption.

A typical laser species, an excimer laser (fundamental wave of a wavelength of 193 ~ 308 ㎚), YAG laser (fundamental wave of wavelength 1064 ㎚), the fiber laser (of a fundamental wave wavelength of 1060 ㎚), CO ₂ laser (the fundamental wave A wavelength of 10600 nm), a semiconductor laser, etc. Basically, there is no problem in using any kind of laser species of any wavelength. It is possible to effectively remove the conductive thin film at the laser light irradiated portion by selecting a laser species which coincides with the absorption wavelength region of any one of the constituent components of the conductive thin film and which can irradiate the wavelength not having strong absorption of the substrate, In addition, damage to the substrate can be avoided. From this viewpoint, as the laser species to be irradiated, the wavelength of the fundamental wave is preferably in the range of 532 to 10700 nm. When a conductive thin film having polyester in its layer structure as a substrate or a thin film in which a part of a conductive thin film having a layer structure of polyester is removed by etching is used, the use of a YAG laser or a fiber laser, Is particularly preferable because it does not absorb the base material and thus it is difficult to damage the base material.

The laser output and the frequency are not particularly limited, but it is possible to remove the conductive thin film at the laser light irradiation site and to control the base material of the base so as not to be damaged. In general, it is preferable to appropriately adjust the laser output in the range of 0.5 to 100 W and the frequency of 10 to 1000 kHz. If the laser output is too low, the removal of the conductive thin film tends to be insufficient, but such a tendency can be avoided to some extent by lowering the laser scanning speed or increasing the number of times of scanning. If the laser output is excessively high, the portion where the conductive thin film is peeled off due to the diffusion of heat from the irradiated portion becomes extremely larger than the diameter of the laser beam, and the line width may become excessively thin or broken. In this respect, the laser output is preferably adjusted in the range of 0.5 to 20 W and the frequency of 10 to 800 kHz, more preferably 0.5 to 12 W, and the frequency of 10 to 600 kHz.

More specifically, the scanning speed of the laser beam is preferably 1000 mm / s or more, more preferably 1500 mm / s or more, still more preferably 2000 mm / s or more, Mm / s. If the scanning speed is too slow, not only the production efficiency is lowered but also the conductive thin film and the substrate may be damaged by thermal history. Although the upper limit of the processing speed is not particularly defined, if the scanning speed is excessively high, the removal of the conductive thin film at the laser light irradiation site may be incomplete and the circuit may be short-circuited. If the scanning speed is too high, it is inevitable to slow down the scanning speed in comparison with the linear portion at the corner portion of the pattern to be formed. Therefore, the thermal history at the corner portion becomes higher than that at the straight portion, There is a possibility that the physical properties of the conductive thin film in the vicinity of the etched portion are significantly lowered.

The scanning of the laser beam may be performed by moving the projectile of the laser beam, moving the object to be irradiated with the laser beam, or combining both, for example, by using the XY stage. It is also possible to scan the laser beam by changing the irradiation direction of the laser beam using a galvanometer mirror or the like.

By using a condenser lens (an achromatic lens or the like) at the time of irradiating laser light, the energy density per unit area can be increased. The advantage of this method is that the energy density per unit area can be increased as compared with the case of using a mask, so that it is possible to perform laser etching processing at a high scanning speed with a small output power. When the condensed laser light is irradiated to the conductive thin film, it is necessary to adjust the focal distance. The adjustment of the focal distance is required to be adjusted according to the film thickness applied to the substrate, but it is preferable to adjust the focal distance so that the predetermined conductive thin film pattern can be removed and removed without damaging the substrate.

Repeatedly scanning the laser light in the same pattern a plurality of times is one of the preferred embodiments. It is possible to completely remove the conductive thin film on the laser light irradiation site by a plurality of scans even if the conductive thin film portion is removed or incompletely removed in the first scanning or the component constituting the removed conductive thin film is again attached to the substrate . Although the upper limit of the number of times of scanning is not particularly limited, care must be taken because there is a possibility that the periphery of the processed portion receives thermal history a plurality of times and is damaged and discolored to deteriorate physical properties of the coating film. In terms of production efficiency, it is natural that the smaller the number of times of scanning, the better.

It is also one of the preferred embodiments that the scanning of the laser light is not repeated in the same pattern a plurality of times. It is a matter of course that the less the number of times of injection, the better the production efficiency, unless adversely affecting the characteristics of the obtained conductive thin film, the conductive laminate and the electric circuit.

Since the conductive thin film of the present invention contains a high-priced conductive powder at a high concentration, considering the total cost required for manufacturing an electric circuit to be produced, the conductive thin material contained in the conductive thin film to be removed from the substrate is recovered and reused It is important. By providing a high-performance dust collector in the vicinity of the laser beam irradiation site and efficiently constructing a system for recovering the conductive powder, a processing method with sufficient profitability can be obtained.

<< Touch panel of the present invention >>

The conductive thin film, the conductive laminate and / or the electric circuit of the present invention can be used as constituent members of the touch panel. The touch panel may be a resistive film type or a capacitive type. The present paste can be applied to any touch panel, but the paste is suitable for formation of fine lines, and thus can be suitably used for electrode wiring of a capacitive touch panel. On the other hand, as the substrate constituting the touch panel, it is preferable to use a substrate having a transparent conductive layer such as an ITO film or a silver nanowire film, or a substrate partially removed by etching.

Example

EXAMPLES In order to further illustrate the present invention, the following examples and comparative examples are given, but the present invention is not limited to these examples at all. On the other hand, the respective measured values described in Examples and Comparative Examples were measured by the following methods.

1. Number average molecular weight

The sample resin was dissolved in tetrahydrofuran so that the resin concentration was about 0.5 wt%, and the solution was filtered with a membrane filter made of polysulfide ethylene having a pore diameter of 0.5 mu m to obtain a GPC measurement sample. (GPC) Prominence manufactured by Shimadzu Seisakusho Co., Ltd., using a differential refractometer (RI system) as a detector, and the resin sample was measured at a column temperature of 30 ° C and a flow rate of 1 ml / min using tetrahydrofuran as a mobile phase, a gel permeation chromatograph Was measured by GPC. On the other hand, the number average molecular weight was calculated in terms of a standard polystyrene conversion value, and a portion corresponding to a molecular weight of less than 1000 was omitted. The GPC column was shodex KF-802, 804L and 806L manufactured by Showa Denko K.K.

2. Glass transition temperature (Tg)

5 mg of the sample resin was sealed in an aluminum sample pan and measured at a heating rate of 20 占 폚 / min up to 200 占 폚 using a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Inc., And the temperature at the intersection of the extension line of the baseline below the transition temperature and the tangent line indicating the maximum inclination at the transition portion.

3. Paste viscosity

The viscosity was measured at 20 rpm at a sample temperature of 25 캜 using a BH-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

4. Storage stability of conductive paste

The conductive paste was placed in a poly container, and the plug with the plug was stored at 40 占 폚 for one month. Measurement of viscosity after storage and evaluation 5. Test pieces made by the conductive laminate test pieces were evaluated.

?: No significant change in viscosity, and initial resistivity, pencil hardness and adhesion were maintained.

X: any one of a remarkable increase in viscosity (at least twice the initial viscosity) or a remarkable decrease in viscosity (1/2 or less of the initial viscosity) and / or a decrease in resistivity, pencil hardness and / or adhesion.

5. Preparation of conductive laminate test piece 1

A 400 mesh stainless steel screen was used for each of a PET film (Rumira S, manufactured by Doraisha) and an ITO film (KH300, manufactured by Oike Kogyo Co., Ltd.) A conductive paste was printed by a printing method to form a pattern having a width of 25 mm and a length of 450 mm without a clearance and subsequently heated in a hot air circulation type drying furnace at 130 DEG C for 30 minutes to obtain a conductive laminated test piece. On the other hand, the coating thickness at the time of printing was adjusted so that the dry film thickness was 5 to 10 mu m.

5. Preparation of conductive laminate test piece 2

An electroconductive paste was printed as shown in Fig. 1 by a screen printing method using a stainless steel screen of 400 mesh on each of the Ag nanowire substrate, an ITO film (KH300, manufactured by Oikei Kogyo Co., Ltd.) The conductive laminate test piece 2 was heated in a drying oven at 130 DEG C for 30 minutes. On the other hand, the coating thickness at the time of printing was adjusted so that the dry film thickness was 5 to 10 mu m.

6. Adhesion

The conductive laminate test piece 1 was evaluated by a peeling 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 good adhesion without peeling, and 0/100 indicates peeling off.

7. Resistivity

The sheet resistance and film thickness of the conductive laminate test piece 1 were measured, and the specific resistance was calculated. The film thickness was measured using a gauge stand ST-022 (manufactured by Onoso K.K.), and the thickness of the cured coating film was measured at five points with the thickness of the PET film as zero point, and the average value thereof was used. The sheet resistance was measured for four test pieces by using MILLIOHMMETER4338B (manufactured by HEWLETT PACKARD), and the average value was used. On the other hand, the range that can be detected by the present milliohmmeter is 1 x 10 ^-2 (Ω · cm) or less, and the resistivity of 1 × 10 ^-2 (Ω · cm) or more is outside the measurement limit.

8. Pencil Hardness

The conductive laminate test piece 1 was placed on a SUS304 plate having a thickness of 2 mm and the pencil hardness was measured according to JIS K 5600-5-4: 1999.

9. Contact Resistance

The resistance values between 1a-2a, 2a-3a and 1a-3a of the conductive laminate test piece 2 were measured, and the contact resistance was calculated from the following equation.

Contact resistance value = ((resistance between 1a and 2a) + (resistance between 2a and 3a) - (resistance between 1a and 3a) / 2

<Initial value>

○: Contact resistance value ≤50 Ω

X: Contact resistance value> 50 Ω

&Lt; After Humidity Durability Test >

○: Contact resistance value after initial humidification test / initial contact resistance value ≤1.2

X: contact resistance value after initial humidification test / initial contact resistance value> 1.2

10. Surface roughness

The surface roughness Ra of the conductive laminate test piece 1 was measured using a surface roughness meter (Handy's Surf E-35B, manufactured by Tokyo Seimitsu Co., Ltd., based on JIS-1994).

11. Humidity resistance test

The conductive laminate test pieces 1 and 2 were heated at 80 占 폚 for 300 hours, then heated at 85 占 폚 and 85% RH (relative humidity) for 300 hours, then left at room temperature for 24 hours, Respectively.

12. Evaluation of laser etching processing suitability

A conductive paste was printed and printed in a rectangle of 2.5 x 10 cm on a polyester base material (Rumira S (thickness: 100 mu m) manufactured by Doraisha) by a screen printing method. The screen plate was printed at a squeegee speed of 50 mm / s using a 400 stainless steel mesh (emulsion thickness of 10 mu m, line diameter of 18 mu m (manufactured by Murakami Co., Ltd., calendering)). After the application of printing, drying was performed at 130 캜 for 30 minutes in a hot air circulation type drying furnace to obtain a conductive thin film. On the other hand, the paste was diluted so as to have a film thickness of 5 to 7 mu m. Subsequently, the conductive thin film prepared by the above method was subjected to laser etching to produce a pattern having four linear portions having a length of 50 mm, as shown in Fig. 1, and used as a test piece for evaluation of laser etching process suitability. The laser etching between the lines in Fig. 1 was performed by scanning the laser beam with a beam diameter of 30 mu m at a pitch of 50 mu m (L / S = 20/30 mu m) twice. A YAG laser (wavelength: 1064 nm) was used as the laser light source, and the frequency was 200 kHz, the output was 11 W, and the scanning speed was 3000 mm / s.

The evaluation items and measurement conditions are as follows.

(Laser etching processing width evaluation)

In the above laser etching processability evaluation test piece, the line width of the silver coating after the laser etching was measured. The measurement was carried out using a laser microscope (Keynes VHX-1000), and the evaluation criteria were as follows.

○; The line width of the portion from which the conductive thin film is removed is 28 to 32 탆

?; The line width of the portion where the conductive thin film is removed is 24 to 27 占 퐉 or 33 to 36 占 퐉

×; The line width of the portion where the conductive thin film is removed is not more than 23 占 퐉, or not less than 37 占 퐉

(Conductivity Evaluation between Laser Etching and Machining Abrasive Sheets)

Evaluation was made as to whether or not conduction between both ends of the fine wire was ensured in the above-described laser etching processability evaluation test piece. Concretely, the presence or absence of conduction is checked by checking the connection between the terminal A1 and the terminal B1, between the terminal A2 and the terminal B2, between the terminal A3 and the terminal B3, and between the terminal A4 and the terminal B4, Respectively.

○; There is continuity between both ends of the fine wire for all four fine wires.

?; There is no conduction between the ends of the fine wire for one to three of the four fine wires.

×; There is no continuity between both ends of the fine wire for all four fine wires.

(Evaluation of laser etching process suitability 2 Insulation between adjacent fine wires)

In the above laser etching processability evaluation test piece, evaluation was made as to whether or not insulation between adjacent fine lines was ensured. More specifically, the presence or absence of conduction between the terminals A1 and A2, between the terminals A2 and A3, and between the terminals A3 and A4 was checked to determine the following evaluation criteria.

○; All adjacent wires are insulated.

?; Some of the adjacent wires are insulated.

×; No insulation between all adjacent wires

(Evaluation of residue of the portion from which the conductive thin film was removed)

In the above laser etching processability evaluation test piece, the portion from which the conductive thin film was removed was observed with a laser microscope, and whether or not the residue was attached was judged according to the following evaluation criteria.

?: No residue was found in the area where the conductive thin film was removed.

B: Residual part is present in the area where the conductive thin film is removed.

X: A lot of residue is observed in the area where the conductive thin film is removed.

(Evaluation of adhesion between conductive thin film and substrate after laser etching)

The adhesion to the base material of the portion where the conductive thin film remaining in the portion where the conductive thin film was removed in the above-mentioned laser etching processability evaluation test piece was measured with a tape using Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd.) And evaluated by a peel test. This evaluation was carried out immediately after 24 hours of the preparation of the test piece (initial stage) and then for 120 hours under a moist heat environment of 85 ° C and 85% RH (relative humidity), and after standing at room temperature for 24 hours (After the wet heat resistance test).

○: No peeling. DELTA: Partially peeled off. X: all peeled off.

Example 1

2857 parts (1000 parts in terms of solid content) of the phenoxy resin PH-1 dissolved in EDGAC so that the solid concentration was 35 mass%, 8361 parts of Powder 1, 100 parts of Curing agent 1, 59 parts of leveling agent, 1, and 164 parts of EDGAC as a solvent were mixed and dispersed by passing through a chilled three-roll mill kneader twice. Subsequently, a 500-mesh filter (stainless steel mesh filter (wire diameter: 25 mu m, mesh size: 30 mu m)) was attached to a paste filter (PF320A manufactured by ProTek) to filter the paste. Thereafter, the obtained conductive paste was printed in a predetermined pattern and then dried at 130 占 폚 for 30 minutes to obtain a conductive thin film. Basic conductive properties were measured using this conductive thin film, followed by examination of laser etching. The evaluation results of the paste and paste coating film and laser etching workability are shown in Table 1.

Examples 2 to 11

Examples 2 to 12 were conducted by changing the resin and the blend of the conductive paste. The results of blending and evaluation of the conductive paste are shown in Table 1. In the Examples, excellent physical properties of the coating film were obtained by heating at a relatively low temperature of 130 占 폚 for 30 minutes in an oven for a short time. Also, the adhesion to the ITO film and the adhesion after the wet heat environment test were good.

In Table 1, the following components were used as the binder component, conductive powder, additive and solvent.

Binder component PH-1: manufactured by InChem PKHB (phenoxy resin, number average molecular weight 16000, Tg = 64 DEG C)

Binder component PH-2: manufactured by InChem PKHC (phenoxy resin, number average molecular weight 21,000, Tg = 66 DEG C)

Binder component PH-3: InChem manufactured PKHC modified product (phenoxy resin, number average molecular weight 21,000, Tg = 67 캜)

Binder component PH-4: manufactured by InChem PKHH (phenoxy resin, number average molecular weight 27000, Tg = 67 ° C)

Binder component PH-5: YP-50 (phenoxy resin, number average molecular weight 27000, Tg = 65 캜) manufactured by Shinnitetsu Sumikin Kagaku Co.,

Binder component PH-6: YP-70 (phenoxy resin, number average molecular weight 28,000, Tg = 60 캜) manufactured by Shinnitetsu Sumikin Kagaku Co.,

Binder component PH-7: jER-1010 (phenoxy resin, number average molecular weight 8000, Tg = 55 占 폚) manufactured by Mitsubishi Kagaku Co.,

Binder component PH-8: jER-1002 (phenoxy resin, number average molecular weight 1000, Tg = 54 占 폚) manufactured by Mitsubishi Kagaku Co.,

Binder component PS-1: RV-200 (polyester resin, number average molecular weight 27,000, Tg = 67 캜) manufactured by Toyobo Co.,

Silver powder 1: agglomerated powder (D50: 0.5 占 퐉)

Silver powder 2: flake powder (D50: 1 占 퐉)

Ketchen Black: Ketchen ECP600JD manufactured by Lion Corporation

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

Curing agent 2: BI-7960

Curing catalyst: KS1260 manufactured by Kyodo Yakuhin Co., Ltd.

Leveling agent: Kyoeisha Kagaku Co., Ltd. MK

Dispersant 1: Disperbyk 2155 manufactured by Big Chem Japan Co., Ltd.

Additive 1: Silica R972 manufactured by Nippon Aerosil Co., Ltd.

Additive 2: dimethylolbutanoic acid (manufactured by Nippon Kasei K.K.) dissolved in EDGAC at a solid content of 20%

Additive 3: BYK-410 manufactured by BICKEMI Japan Co., Ltd.

EDGAC: Ethyl diglycol acetate manufactured by Daicel Co.

BMGAC: manufactured by Daicel Co. butyl glycol acetate

DBE: a mixture of dimethyl ester of adipic acid, succinic acid and glutaric acid manufactured by DuPont Co.

Synthesis of PH-3

400 parts of phenoxy resin PH-2 was added to a reaction vessel equipped with a stirrer, a condenser and a thermometer, and then 489 parts of ethyl diglycol acetate (EDGAC) was added and dissolved at 85 占 폚. Thereafter, 3 parts of trimellitic acid was added, and 0.19 parts of dimethylaminopyridine and 0.48 part of diazabicyclo-decene were added as a catalyst and reacted at 85 ° C for 4 hours to obtain a solution of phenoxy resin PH-3. The solid content concentration of the obtained phenoxy resin solution was 35 mass%. The thus obtained resin solution was dropped on a polypropylene film and stretched using an applicator made of stainless steel to obtain a thin film of the resin solution. This was allowed to stand in a hot-air drier adjusted to 120 DEG C for 3 hours to volatilize the solvent. Subsequently, the resin thin film was peeled off from the polypropylene film to obtain a film-like dry resin thin film. The thickness of the dried resin thin film was about 30 탆. The dried resin thin film was used as a sample resin of phenoxy resin PH-3, and the evaluation results of various resin properties are shown in Table 1.

INDUSTRIAL APPLICABILITY The conductive paste for laser etching of the present invention can provide an electroconductive thin film which is excellent in wet heat environment reliability and can maintain coating film durability as a conductive thin film while maintaining suitability for laser etching processing. Telephone, notebook computer, electronic book, and the like.

1a, 2a, 3a, 4a: terminal A
1b, 2b, 3b, 4b: thin line B
1c, 2c, 3c, 4c: terminal C

Claims (11)

A conductive paste for laser etching comprising an organic component (A), a silver powder (B) and an organic solvent (C) comprising a thermoplastic and / or thermosetting resin is characterized in that as the binder resin (a) , And a phenoxy resin. The conductive paste for laser etching according to claim 1, wherein the binder resin (a) contains 60% by weight or more of a phenoxy resin. The conductive paste for laser etching according to claim 1 or 2, wherein the binder resin (a) has a number average molecular weight of 3,000 to 100,000. The conductive paste for laser etching according to any one of claims 1 to 3, characterized in that the conductive paste is filtered. A conductive thin film formed from the conductive paste for laser etching processing according to any one of claims 1 to 4. The conductive laminate according to claim 5, wherein the conductive thin film and the substrate are laminated. The conductive laminate according to claim 6, wherein the substrate has a transparent conductive layer. An electric circuit using the conductive thin film according to claim 5 or the conductive laminate according to claim 6 or 7. An electric circuit having a wiring portion formed by irradiating a part of the conductive thin film according to claim 5 with a laser beam selected from a carbon dioxide gas laser, a YAG laser, a fiber laser and a semiconductor laser to remove a part of the conductive thin film. The electric circuit according to claim 9, wherein the conductive thin film is formed on the transparent conductive layer. A touch panel comprising the electric circuit according to any one of claims 8 to 10 as a constituent member.

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