KR20180031820A - Conductive paste for laser etching, conductive thin film, and conductive laminate - Google Patents

Abstract

[PROBLEMS] To provide a conductive paste for laser etching which is suitable for laser etching processing capable of producing a high-density electrode circuit wiring having a L / S of 50/50 μm or less, which is difficult to cope with the conventional screen printing method, at a low cost and a low environmental load do.
A conductive paste for laser etching comprising a binder resin (A) containing a thermoplastic resin, a metal powder (B) and an organic solvent (C), a conductive thin film formed by using the conductive paste, a conductive laminate, Circuits and touch panels.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [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 transparent touch panels represented by cellular phones, notebooks, electronic books, and the like have been rapidly advanced and miniaturized. In order to achieve high performance and miniaturization of these electronic devices, it is required to increase the density of the electrode circuit wirings for bonding these electronic components to each other in addition to the miniaturization, high performance, and integration of the electronic components to be mounted. In addition to a resistive film type in which the number of electrode circuit wirings is reduced as a method of a transparent touch panel, the spread of a capacitance type in which the number of electrode circuit wirings is remarkably large has recently progressed rapidly, and from this point of view, have. Further, in order to make the display screen larger, and in the product design, there is a need to make the frame portion where the electrode circuit wiring is arranged to be narrower, and from this point of view also, high density of the electrode circuit wiring is required. In order to satisfy the above-mentioned demand, 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 requirement for L / S is about 100/100 μm or less, and furthermore, the L / S ratio is required to be 50/50 μm or less. The situation becomes difficult 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 a thin line 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 having a copper foil layer formed thereon, and a desired pattern And developing the photosensitive resist. 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 load due to the waste liquid treatment is large, and furthermore, the process is troublesome, and there are many problems including the viewpoints of production efficiency and capacity.

<< Prior art literature >>

(Patent Document 1) Patent Document 1: Japanese Patent Application Laid-Open No. 2010-237573

(Patent Document 2) Patent Document 2: Japanese Patent Application Laid-Open No. 2011-181338

It is an object of the present invention to provide a manufacturing method capable of producing a high-density electrode circuit wiring having an L / S of 50/50 μm or less, which is difficult to cope with by screen printing, at low cost and low environmental load. 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 made intensive investigations on a manufacturing method of disposing the electrode circuit wiring in a high density in the plane direction. As a result, they have found that a layer containing a binder resin and a conductive powder is formed on an insulating substrate, It is possible to produce a high-density electrode circuit wiring having an L / S of 50/50 μm or less, which is difficult to realize by a screen printing method. In addition, a conductive paste suitable for forming a layer containing a binder resin and a conductive powder suitable for such a manufacturing method has been found. That is, the present invention includes the following configurations.

(1) A conductive paste for laser etching processing containing a binder resin (A) containing a thermoplastic resin, a metal powder (B), and an organic solvent (C).

(2) The conductive paste for laser etching according to (1), wherein the binder resin (A) is a thermoplastic resin having a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of 60 to 100 占 폚.

(3) The binder resin composition according to (1), wherein the binder resin (A) is at least one selected from the group consisting of a polyester resin, a polyurethane resin, an epoxy resin, a vinyl chloride resin, Or the conductive paste for laser etching according to (2).

(4) The binder resin (A), an acid value of 50 to 300 equivalents / 10 ⁶ g of polyester resin, and an acid value of 50 to 300 equivalents / 10 ⁶ g of polyester of one or more selected from the group consisting of urethane resin The conductive paste for laser etching according to (1) or (2), which is a mixture.

(5) The conductive paste for laser etching according to any one of (1) to (4), further comprising a laser ray absorbent (D).

(6) An electroconductive thin film formed from the electroconductive paste for laser etching according to any one of (1) to (5).

(7) The conductive laminate according to (6), wherein the conductive thin film and the substrate are laminated.

(8) The conductive laminate according to (7), wherein the substrate has a transparent conductive layer.

(9) An electric circuit using the conductive thin film according to (6), or the conductive laminate according to (7) or (8).

(10) An electric circuit having a wiring portion formed by irradiating a part of the conductive thin film described in (6) with a laser beam selected from a carbonic acid gas laser, a YAG laser, a fiber laser and a semiconductor laser, .

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

(12) A touch panel comprising the electric circuit according to any one of (9) to (11) as a constituent member.

The conductive paste of the present invention is a conductive paste containing a binder resin (A) containing a thermoplastic resin, a metal powder (B) and an organic solvent (C). By adopting such a constitution, In addition, even after the laser etching process, it is possible to form an electroconductive thin film excellent in adhesion to the substrate after initial and moist heat load. Here, excellent suitability for laser etching processing means that at least a part of the conductive thin film is peeled off from the substrate by laser etching to form thin lines of L / S = 30/30 占 퐉. 1) 2) ensuring insulation between adjacent fine wires, and 3) good fine wire shape. Further, the conductive paste containing the laser ray absorbent (D), which is an embodiment of the present invention, has higher sensitivity to laser light irradiation than a conductive paste not containing the laser ray absorbent (D) The laser output can be reduced, and the like.

Fig. 1 is a schematic diagram showing a pattern for irradiating a laser beam to a test piece for evaluating the laser-etching-machining suitability 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 area. The unit of the dimension display in the drawing is mm.

&Lt; Components constituting the conductive paste of the present invention &gt;

The conductive paste for laser etching in the present invention contains a binder resin (A) containing a thermoplastic resin, a metal powder (B) and an organic solvent (C) as essential components.

&Lt; 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, , Vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer, polystyrene, silicone resin, and fluorine resin. These resins can be used alone or as a mixture of two or more kinds. A polyester resin, a polyurethane resin, an epoxy resin, a vinyl chloride resin, a fibrin derivative resin, or a mixture of two or more thereof. Among these resins, a polyurethane resin containing a polyester resin and / or a polyester component as a copolymerization component (hereinafter sometimes referred to as a polyester polyurethane resin) is preferable as the binder resin (A).

One of the advantages of using a polyester resin as the binder resin (A) in the present invention is high degree of freedom in molecular design. The dicarboxylic acid and the glycol component constituting the polyester resin can be selected to freely change the copolymerization component and the functional group to the molecular chain or to the molecular terminal can be easily given. Therefore, the properties of the resin such as the glass transition temperature of the obtained polyester resin and the affinity with the base material and other components to be mixed in the conductive paste can be appropriately adjusted.

Examples of the dicarboxylic acid which can be used as the copolymerization component of the polyester resin used as the binder resin (A) in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid and 2,6- Aliphatic dicarboxylic acids such as dicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and azelaic acid; dibasic acids having 12 to 28 carbon atoms such as dimeric acid; 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic acid, 2-methylhexanedicarboxylic acid, Alicyclic dicarboxylic acids such as phthalic anhydride, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalene dicarboxylic acid and tricyclodecanedicarboxylic acid, Roxy benzoic acid, Milk And hydroxycarboxylic acids such as an acid. In addition, within the scope of not impairing the effect of the invention, unsaturated dicarboxylic acids such as carboxylic acids with more than trivalent anhydride such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid and / or sodium 5-sulfoisophthalate A sulfonic acid metal base-containing dicarboxylic acid such as a salt may be used as a copolymerization component.

Examples of the polyol which can be used as the copolymerization component of the polyester resin used as the binder resin (A) in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5- Pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 1,3-propanediol, 1,8-nonanediol, 1,10-decanediol, and other aliphatic diols, 1,4-cyclohexane And alicyclic diols such as dimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol and dimer diol. In addition, a tri- or higher-valent polyol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, or polyglycerin may be used in combination as a copolymerization component within the range not hindering the effect of the invention.

From the viewpoints of durability such as strength, heat resistance, moisture resistance, and thermal shock resistance, the polyester resin used as the binder resin (A) in the present invention is preferably an aromatic dicarboxylic acid More preferably 80 mol% or more, still more preferably 90 mol% or more, and particularly preferably 98 mol% or more. It is a preferred embodiment that the computational component comprises an aromatic dicarboxylic acid. If the copolymerization ratio of the aromatic dicarboxylic acid component is too low, the obtained polyester resin tends to have a lower glass transition temperature than 60 ° C, and the resulting conductive thin film tends to have poor wettability and durability.

From the viewpoints of durability such as strength, heat resistance, moisture resistance and thermal shock resistance, the polyester resin used as the binder resin (A) in the present invention is preferably a polyester resin having a carbon number of 4 Or less, more preferably 80 mol% or more, and still more preferably 95 mol% or more. If the copolymerization ratio of the glycol having 4 or less carbon atoms in the main chain is too low, the glass transition temperature of the resulting polyurethane resin becomes lower than 60 占 폚, and the resulting electroconductive thin film tends to have poor wettability and durability.

It is also a preferred embodiment to use a polyurethane resin as the binder resin (A) in the present invention. As in the case of the polyester resin, as for the polyurethane resin, appropriate components are selected as the copolymerizable component constituting the polyurethane resin, and functional groups are added to the molecular chain or to the molecular ends, The affinity between the substrate and other components to be mixed with the conductive paste can be suitably adjusted.

The copolymer component of the polyurethane resin is not particularly limited, but is preferably a polyester polyurethane resin using a polyester polyol as a copolymerization component from the viewpoints of freedom in design, resistance to humidity and heat, and durability. Suitable examples of the polyester polyol include polyols in polyester resins usable as the binder resin (A) in the present invention.

The polyurethane resin used as the binder resin (A) in the present invention can be obtained, for example, by the reaction of a polyol and a polyisocyanate. Examples of the polyisocyanate that can be used as the copolymerization component of the polyurethane resin include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylenediisocyanate, 4,4'-diphenylmethane diisocyanate, m 4,3'-dimethoxy-4,4'-biphenylene diisocyanate, 2,6-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, m-xylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene di Isocyanate and the like, and may be any of aromatic diisocyanate, aliphatic diisocyanate and alicyclic diisocyanate. In addition, as long as the effect of the present invention is not impaired, a trivalent or more isocyanate compound may be used as a copolymerization component.

The polyurethane resin used as the binder resin (A) in the present invention may be copolymerized with a compound having a functional group capable of reacting with isocyanate, if necessary. As the functional group capable of reacting with the isocyanate, a hydroxyl group and an amino group are preferable, and either one of them may be used, or both of them may be used. Specific examples thereof include dimethylolbutanoic acid, dimethylolpropionic acid, 1,2-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2,2- Propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2- 3-hydroxypropyl-2 ', 2'-dimethyl-3'-hydroxypropanate, 2-n-butyl- 1,3-propanediol, 3-pentyl-1,5-pentanediol, 3-phenyl-1,5-pentanediol, 2,5 -Dimethyl-3-sodium sulfo-2,5-hexanediol, dimer diol (for example, PRIPOOL-2033 manufactured by Uniqema International Co., Ltd.), a compound having two hydroxyl groups in one molecule, trimethylolethane, , Alcohols having three or more hydroxyl groups in one molecule such as glycerin, pentaerythritol and polyglycerin, monoethanolamine, diethanolamine, Amino alcohols having at least one hydroxyl group and an amino group in one molecule such as ethanolamine, ethylenediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, , 11-undecanediamine, and 1,12-dodecanediamine; alicyclic diamines such as 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, 4,4'- And aromatic diamines such as diaminodiphenyl ether, and the like. The compound having a functional group capable of reacting with two or more isocyanates in one molecule having a number average molecular weight of less than 1,000 may be used alone or in combination with plural compounds.

The number average molecular weight of the binder resin (A) in the present invention is not particularly limited, but it is preferable that the number average molecular weight is 5,000 to 60,000. 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. When the glass transition temperature is low, the suitability for laser etching processing may be improved. However, there is a fear that the reliability of the wet heat environment as the conductive thin film is lowered, and furthermore, the surface hardness is lowered, There is a fear that the paste-containing component migrates to the contact side and the reliability of the conductive thin film is lowered. On the other hand, the glass transition temperature of the binder resin (A) used in the present invention is preferably 150 占 폚 or lower, more preferably 120 占 폚 or lower in consideration of printability, adhesion, solubility, paste viscosity, And more preferably 100 DEG C or less.

Although the acid value of the binder resin (A) in the present invention is not particularly limited, the acid value of the binder resin (A) in a specific range may significantly improve the adhesion to the base material. In the case of laser etching of the conductive thin film, the temperature around the laser irradiation site rises and the adhesiveness between the conductive thin film and the substrate may be lowered. However, by using a binder resin having an acid value within a specific range as the binder resin (A) , Deterioration of the adhesion can be suppressed in some cases. The acid value of the binder resin (A) is preferably 50 to 350 eq / ton, more preferably 100 to 250 eq / ton. When the acid value is too low, the adhesion between the conductive thin film to be formed and the substrate tends to be lowered. On the other hand, if the acid value is too high, the conductivity of the formed conductive thin film becomes high, and the hydrolysis of the binder resin may be accelerated by the catalytic action of the carboxyl group, leading to a decrease in the reliability of the conductive thin film.

&Lt; Metal Powder (B) >

Examples of the metal powder (B) used in the present invention include noble metal powders such as silver powder, gold powder, platinum powder and palladium powder, noble metal powders such as copper powder, nickel powder, aluminum powder and brass powder, And non-metallic powders obtained by plating or alloying. These metal powders may be used alone or in combination. Among them, in consideration of conductivity, stability, cost, etc., it is preferable to mainly use silver powder or silver powder.

The shape of the metal powder (B) used in the present invention is not particularly limited. Examples of conventionally known shapes of the metal powder include flake-shaped (scaly), spherical, twig-shaped (dendrite-shaped), and spherical primary particles described in JP-A-9-306240 (Coagulation type), and the like. Of these, spherical, coagulated and flaky metal powders are preferably used.

The center diameter (D50) of the metal powder (B) used in the present invention is preferably 4 mu m or less. By using the metal 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 metal powder having a center diameter larger than 4 탆, the fine line shape after the laser etching process is deteriorated, and as a result, fine lines may contact each other and short-circuit may occur. Further, in the laser etching process, there is a possibility that the conductive thin film, once peeled off and removed, is attached again to the processed portion. Although the lower limit of the central diameter of the metal powder (B) is not particularly limited, it is preferable that the central diameter is 80 nm or more because the metal powder (B) tends to aggregate when the particle diameter becomes finer and consequently becomes difficult to disperse. When the center diameter is smaller than 80 nm, the cohesive force of the metal powder is increased and the laser etching processing becomes worse, and it is not preferable from the viewpoint of cost.

The center diameter (D50) is the particle diameter (mu m) at which the accumulated value becomes 50% in the cumulative distribution curve (volume) obtained by a certain measuring method. In the present invention, the cumulative distribution curve is measured in the 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 metal powder (B) is preferably 400 parts by mass or more, and more preferably 560 parts by mass or more, per 100 parts by mass of the thermoplastic resin (A) from the viewpoint of good conductivity of the conductive thin film formed. 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 with 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 preferably has a boiling point of 100 占 폚 or more and less than 300 占 폚, 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 metal 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 the reliability of the coating film to deteriorate.

In addition, as the organic solvent (C) usable in the present invention, it is preferable that the thermoplastic resin (A) is soluble and the metal powder (B) can be well dispersed. Specific examples include ethyleneglycol acetate (EDGAC), butylglycol acetate (BMGAC), butyldiglycol acetate (BDGAC), cyclohexanone, toluene, isophorone,? -Butyrolactone, benzyl alcohol, (E.g. DBE manufactured by DuPont), tapiron, and the like can be given as a mixture of propylene glycol monomethyl ether acetate, Solvesso 100, 150, 200, a mixture of dimethyl esters of adipic acid, succinic acid and glutaric acid, Of these, EDGAC, BMGAC, BDGAC, and mixtures thereof are preferable from the viewpoints of excellent solubility of the blending components of the thermoplastic resin (A), solvent volatility at the time of continuous printing, and good suitability for printing by a screen printing method or the like. Solvents are preferred.

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 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 extremely high, so that, for example, the screen printing property at the time of forming the conductive thin film is remarkably lowered, The etching processability 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 absorber (D) refers to an additive having strong absorption at the wavelength of the laser light, and the laser light absorber (D) itself may be electrically conductive or nonconductive. For example, when a YAG laser having a fundamental wave wavelength 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, thereby facilitating the volatilization and thermal decomposition of the binder resin (A) due to heat generation, and as a result, the 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. The carbon-based filler has an effect of enhancing the conductivity of the conductive thin film of the present invention. For example, 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 The sensitivity of the laser light irradiation is increased because the conductive thin film absorbs the laser light with high efficiency. Thus, 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 Effect 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, based on 100 parts by weight of the metal powder (B). When the compounding ratio of the carbon-based filler is too low, the effect of increasing the conductivity and the effect of 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 may be adsorbed to the void portion of the carbon and the adhesion with the substrate may be deteriorated .

Among the laser ray absorbent (D) usable in the present invention, examples that are nonconductive include conventionally known dyes, pigments and infrared 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, Pigments such as a black pigment, 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, etc., . 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 available from 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-absorbent (D) is too low, the effect of increasing 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, 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; Other, talc, bentonite, talc, calcium carbonate, kaolin, glass fiber, mica and the like can be used. By adding these inorganic materials, it may be possible to improve the printability, heat resistance, mechanical properties and long-term durability. Among them, in the conductive paste of the present invention, silica is preferable from the viewpoint of imparting durability and printability, particularly screen printing suitability.

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 flame retardant, a pigment and a dye. As the resin decomposition inhibitor, carbodiimide, epoxy and the like may be appropriately added. These can be used alone or in combination.

&Lt; Curing agent (E) >

In the conductive paste of the present invention, a curing agent capable of reacting with the binder resin (A) may be compounded to such an extent that the effect of the present invention is not impaired. By blending a curing agent, there is a possibility that the curing temperature is high and the load of the production process is increased. However, it is expected that the heat and humidity resistance of the coating film can be improved by the cross-linking caused by heat generated at the time of drying the coating film or during laser etching.

The type of curing agent capable of reacting with the binder resin (A) of the present invention is not particularly limited, but an isocyanate compound is particularly preferable from the viewpoint of adhesion, flex resistance, curability and the like. As the isocyanate compound, it is preferable to use an isocyanate group-blocked isocyanate compound 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, epoxy resins 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 relative to 100 parts by mass of the binder resin (A) More preferably 2 to 20 parts by mass.

Examples of the isocyanate compound that can be compounded in the conductive paste of the present invention include aromatic or aliphatic diisocyanates, trivalent or higher polyisocyanates, and the like, and may be any of a low-molecular compound and a high-molecular 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, It can be obtained by a 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, and aromatic amines, imides, acetylacetone, acetic acid esters, malonic acid ethyl esters , Mercaptans, imines, imidazoles, ureas, diaryl compounds, sodium bisulfite, and the like. Among them, oxides, imidazoles and amines are particularly preferable from the viewpoint of curability.

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

The conductive paste of the present invention preferably has an F value of 60 to 95%, more preferably 75 to 95%. F value is a numerical value showing 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 includes the conductive powder, the binder resin, other curing agents, and additives in a mass part of the conductive powder and a mass of the solid component in the mass parts of the components other than the solvent. 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 substrate and / or the surface hardness of the conductive thin film tend to be lowered. Here, the conductive powder refers to both of the metal powder (B) and the conductive powder containing a non-metal.

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

The conductive paste of the present invention can be produced by dispersing the thermoplastic resin (A), the metal powder (B), the organic solvent (C), and other components as required, in three rolls or the like as described above. Here, an example of a more detailed production procedure is shown. The thermoplastic resin (A) is first dissolved in the organic solvent (C). Thereafter, the metal powder (B) and, if necessary, an additive are added, and preliminary dispersion is carried out by using 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. It may be dispersed by using other dispersing apparatuses such as a bead mill, a kneader and an extruder.

<< 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, subsequently volatilizing the organic solvent (C) contained in the coating film, and drying 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 spreading in the industry for forming the electric circuit by using the conductive paste. It is preferable that the conductive paste is applied or printed at a position somewhat larger than the area of the conductive thin film finally required as the electric circuit from the viewpoint of reducing the load of the laser etching process and efficiently forming the electric circuit of the present invention.

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. Thickness of the base material is not particularly limited, but is preferably 50 to 350 占 퐉, and 100 to 250 占 퐉 is more preferable from the viewpoints of mechanical properties, shape stability, and 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 for example, an ITO film composed mainly of indium oxide and tin may be used. The transparent conductive layer may be formed not only on the entire surface of the substrate but also partially removed 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 transparent conductive layer as a base 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 3 占 퐉 or more and 30 占 퐉 or less, more preferably 5 占 퐉 or more and 20 占 퐉 or less, more preferably 5 占 퐉 or more and 20 占 퐉 or less, 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, the 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 easiness of etching of the conductive thin film is changed, and there is a tendency that a short between the lines due to insufficient etching or a disconnection due to excessive etching tends to occur. Therefore, the fluctuation of the film thickness is preferably small.

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

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 certain components constituting the conductive thin film of the present invention have strong absorption.

Typical types of laser include excimer laser (wavelength of fundamental wave of 193-308 nm), YAG laser (fundamental wave of 1064 nm), fiber laser (fundamental wave of 1060 nm), CO2 laser A wavelength of 10600 nm), a semiconductor laser, etc. Basically, there is no problem even if a laser species of any wavelength or any wavelength is used. It is possible to efficiently remove the conductive thin film at the laser beam irradiation site by selecting a laser species that matches the absorption wavelength region of any one of the constituent components of the conductive thin film and can irradiate a wavelength at which the substrate does not have strong absorption, Can be avoided. From this point of view, it is preferable that the wavelength of the fundamental wave is in the range of 532 to 10700 nm for the laser species to be irradiated. For example, when a transparent conductive laminate in which an ITO layer is formed on a polyester film or a polyester film, or a laminate in which an ITO layer is formed on a polyester film and a part of which is removed by etching is used as a substrate, The use of a YAG laser or a fiber laser is particularly preferable because it does not cause damage to the base material because the base material does not absorb at the wavelength of the fundamental wave.

The laser output and the Q modulation frequency are not particularly limited, but the conductive thin film at the laser irradiation site can be removed and the substrate of the base is not damaged. In general, it is preferable to appropriately adjust the laser output in the range of 0.5 to 100 W and the Q modulation frequency in the range of 10 to 400 kHz. If the laser output is too low, the removal of the conductive thin film tends to be insufficient. However, such a tendency can be avoided to some extent by lowering the scanning speed of the laser 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.

More specifically, the scanning speed of the laser beam is preferably not less than 1000 mm / s, more preferably not less than 1500 mm / s, more preferably not more than 2000 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 condensing lens (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 it is possible to increase the energy density per unit area as compared with the case of using a mask so that even a small output laser oscillator can perform laser etching processing at a high scanning speed have. 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 as not to damage the substrate, and to peel and remove a predetermined conductive thin film pattern.

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 at the laser light irradiating site by a plurality of scans even when the conductive thin film portion in which the removal is incomplete in the first scanning or the component constituting the removed conductive thin film is again attached to the substrate It becomes. The upper limit of the number of times of scanning is not particularly limited, but care must be taken because there is a possibility that the periphery of the processed portion receives thermal history a plurality of times to be damaged, discolored, or deteriorated in physical properties of the coated film. In terms of production efficiency, it is natural that the smaller the number 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.

<< 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. 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 substrate partially removed by etching.

Example

The following examples and comparative examples are provided to further illustrate the present invention, but the present invention is not limited at all by the examples. Each measurement value described in Examples and Comparative Examples was measured by the following method.

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 through a membrane filter made of poly (tetrafluoroethylene) having a pore diameter of 0.5 mu m to give a GPC measurement sample. (GPC) Prominence manufactured by Shimadzu Corporation and using a differential refractometer (RI system) as a detector. The column was subjected to column chromatography at a column temperature of 30 ° C and a flow rate of 1 ml / min to obtain a resin sample GPC measurement was performed. The number average molecular weight was calculated in terms of standard polystyrene, and the portion corresponding to a molecular weight of less than 1000 was omitted. GPC columns were 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 temperature raising rate of 20 캜 / min up to 200 캜 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. Acid value

0.2 g of the sample resin was precisely weighed and dissolved in 20 ml of chloroform. Subsequently, the phenolphthalein solution was used for the indicator and titration was performed with 0.01 N potassium hydroxide (ethanol solution). The unit of acid value was eq / ton, that is, the equivalent per 1 ton of sample.

4. Resin composition

The sample resin was dissolved in chloroform-d and the resin composition was determined by ¹ H-NMR analysis using a 400 MHz-NMR apparatus manufactured by Varian Corporation.

5. Paste viscosity

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

6. Storage stability of conductive paste

The conductive paste was put in a poly container and sealed, and stored at 40 占 폚 for one month. After storage, the viscosity was measured and the test piece produced by the above 5. conductive laminate test piece was evaluated.

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

X: It is confirmed whether the remarkable increase in viscosity (at least twice the initial viscosity) or the decrease in the viscosity (1/2 or less of the initial viscosity) and / or the decrease in the resistivity, pencil hardness and / or adhesion property are observed.

7. Preparation of conductive laminate test piece

A 200 mesh polyester screen was used for each of the PET film (Lumirra S manufactured by Toray Industries, Inc.) and the ITO film (KH300 manufactured by OIKE INDUSTRY CO., LTD.) Which had been subjected to the annealing treatment to a thickness of 100 mu m A conductive paste was printed to form a solid coating pattern having a width of 25 mm and a length of 450 mm and subsequently heated in a hot air circulation type drying furnace at 120 DEG C for 30 minutes to obtain a conductive laminated test piece. The coating thickness at the time of printing was adjusted so that the dry film thickness was 6 to 10 mu m.

8. Adhesiveness

The conductive laminate test piece 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.

9. Resistivity

The sheet resistance and film thickness of the conductive laminate test piece were measured, and the specific resistance was calculated. The thickness of the cured coating film was measured at five points using a gauge stand ST-022 (manufactured by Onoso K.K.) with the thickness of the PET film as zero point, and the average value was used. The sheet resistance was measured with respect to four test pieces by using MILLIOHMMETER 4333B (manufactured by HEWLETT PACKARD), and the average value was used. In addition, the range that can be detected by the present milliohmmeter is 1 x 10 ^-2 or less (Ω · cm), and the resistivity of 1 × 10 ^-2 (Ω · cm) or more is outside the measurement limit.

10. Pencil Hardness

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

11. Humidity resistance test

The conductive laminate test piece was heated at 80 占 폚 for 300 hours, then heated at 85 占 폚 and 85% RH (relative humidity) for 300 hours, and then left at room temperature for 24 hours, followed by various evaluations.

12. Evaluation of laser etching processing suitability

A conductive paste was printed and printed in a rectangular shape of 2.5 x 10 cm on a polyester base material (Lumiras S (thickness: 100 mu m) manufactured by Dora Manufacturing Co., Ltd.) by screen printing. The screen plate was printed at a squeegee speed of 150 mm / s using a T400 stainless steel mesh (emulsion thickness 10 占 퐉, line diameter 23 占 퐉 (manufactured by Tokyo Process Service Co., Ltd.)). After printing application, drying was carried out in a hot air circulation type drying oven at 120 DEG C for 30 minutes to obtain a conductive thin film. Further, the paste was diluted so as to have a film thickness of 5 to 12 占 퐉. Subsequently, the conductive thin film prepared by the above method was subjected to laser etching to produce a pattern having four linear portions each having a length of 50 mm shown in Fig. 1, and used as a test piece for evaluation of laser etching process suitability. The laser etching between the lines of the linear portions was performed by scanning the laser beam having a beam diameter of 30 탆 at a pitch of 60 탆 twice each time. A fiber laser was used as the laser light source, and the Q modulation frequency was 200 kHz, the output was 10 W, and the scanning speed was 2700 mm / s.

The evaluation items and measurement conditions are as follows.

(Laser etching processing width evaluation)

The linewidth of the portion where the conductive thin film was removed was measured in the above-mentioned laser etching processability evaluation test piece. The measurement was carried out using a laser microscope (Keynes VHX-1000), and it was judged based on evaluation criteria below.

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

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

×; 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

(Evaluation of laser etching processing suitability (1) Conductivity between both ends of thin wire)

Evaluation was made as to whether or not conduction between the both ends of the fine lines 1b, 2b, 3b, and 4b was ensured in the above laser etching processability evaluation test piece. More specifically, the presence or absence of conduction was checked between the terminals 1 a and 1 c, between the terminals 2 a and 2 c, between the terminals 3 a and 3 c, and between the terminals 4 a and 4 c, "

○; There is continuity between both ends of thin wire with respect to all four wires.

?; There is no continuity between the two ends of the fine wire in relation to one to three of the four fine wires.

×; There is no continuity between the two ends of the fine wire with respect to all four fine wires.

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

Evaluation was made as to whether or not the insulation between the adjacent fine lines in the test piece for evaluating suitability for laser etching was secured. More specifically, the presence or absence of conduction was checked between the terminals 1a and 2a, between the terminals 2a and 3a, and between the terminal 3a and the terminal 4a, and a test was conducted.

○; 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, a portion where 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.

[Delta]: There is a small amount of residue on the area where the conductive thin film is removed.

X: The residue of the conductive thin film was 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 after standing for 24 hours at room temperature (after moisture resistance test) for 24 hours immediately after the test piece was prepared (initial) and after that for 120 hours under a humid environment of 85% RH and 85% RH (relative humidity) .

○: No peeling. ?: Partially peeled off. X: All peeled off.

Production Example of Resin

Production Example of Polyester Resin P-1

700 parts of terephthalic acid, 700 parts of isophthalic acid, 16.9 parts of anhydrous trimellitic acid, 983 parts of ethylene glycol and 154 parts of 2-methyl-1,3-propanediol were fed into a reaction vessel equipped with a stirrer, a condenser and a thermometer, And the temperature was raised from 160 ° C to 230 ° C over 3 hours under a pressure of 2 atm to carry out an esterification reaction. After depressurization, 0.92 part of tetrabutyl titanate was poured, the pressure in the system was gradually reduced, the pressure was reduced to 5 mmHg over 20 minutes, and the polycondensation reaction was carried out at 260 DEG C for 40 minutes under a vacuum of 0.3 mmHg or less . Subsequently, the mixture was cooled to 220 DEG C under a nitrogen stream, 50.6 parts of trimellitic anhydride was added, and the reaction was carried out for 30 minutes to obtain a polyester resin. Table 1 shows the composition and physical properties of the obtained copolymer polyester resin P-1.

Production Example of Polyester Resins P-2 to P-11

Polyester resins P-2 to P-11 were prepared by changing the type and blending ratio of the monomers in the production example of the polyester resin P-1. The composition and the resin properties of the obtained copolymer polyester resin are shown in Tables 1 and 2.

BPE-20F: ethylene oxide adduct of bisphenol A (manufactured by Sanyo Chemical Industries, Ltd.)

BPX-11: Propylene oxide adduct of bisphenol A (manufactured by Asahi Denka Co., Ltd.)

Production Example of Polyurethane Resin U-1

1000 parts of polyester resin P-7, 80 parts of neopentyl glycol (NPG) and 90 parts of dimethylolbutanoic acid (DMBA) were put in a reaction vessel equipped with a stirrer, a condenser and a thermometer, and ethyldiglycol acetate (EDGAC ), And dissolved at 85 캜. Thereafter, 460 parts of 4,4'-diphenylmethane diisocyanate (MDI) was added and reacted at 85 DEG C for 2 hours. Then, 0.5 part of dibutyltin dilaurate was added as a catalyst, Lt; / RTI &gt; The solution was then diluted with 1940 parts of EDGAC to obtain a solution of polyurethane resin U-1. The solid content concentration of the obtained polyurethane 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 the polyurethane resin U-1, and the evaluation results of various resin properties are shown in Table 3.

Production Example of Polyurethane Resins U-2 to U-8

Polyurethane resins U-2 to U-8 were synthesized in the same manner as in the production example of polyurethane resin U-1 except that polyester polyol, a compound having a group reacting with isocyanate and polyisocyanate were used instead of those shown in Table 3 . The evaluation results of the resin properties of the polyurethane resins U-2 to U-8 are shown in Table 3.

DMBA: dimethylolbutanoic acid

NPG: neopentyl glycol

DMH: 2-butyl-2-ethyl-1,3-propanediol

MDI: 4,4'-diphenylmethane diisocyanate

IPDI: isophorone diisocyanate

Example 1

2860 parts (1000 parts in terms of solid part) of a solution obtained by dissolving polyester resin P-1 in EDGAC at a solid content concentration of 35% by mass, 7,888 parts of flake type silver powder 1, 71 parts of MK-CONK, 30 parts of Disperbyk 130 manufactured by Big Chem Japan Co., Ltd., and 300 parts of EDGAC as a dispersant were mixed and dispersed three times in a chilled three-roll kneader. Thereafter, the obtained conductive paste was printed in a predetermined pattern and then dried at 120 ° C for 30 minutes to obtain a conductive thin film. Basic conductive properties were measured using this conductive thin film, and then laser etching processing was examined. The evaluation results of the paste and paste coating film and the laser etching workability are shown in Table 4.

Examples 2 to 13

Examples 2 to 17 were carried out by changing the resin and the composition of the conductive paste. The results of mixing and evaluation of the conductive paste are shown in Tables 4 to 6. Good physical properties of the coating film could be obtained by heating in an oven at 120 DEG C for 30 minutes at a relatively low temperature and for a short period of time. Adhesion to the ITO film and adhesion after the wet heat environment test were also good.

In Tables 4 to 7, the following resins were used as the binder resin, conductive powder, additive and solvent.

Binder resin PH-1: manufactured by InChem PKKH (phenoxy resin, number average molecular weight 14000, Tg = 71 캜)

Silver powder 1: Flake type silver powder (D50: 2 占 퐉)

Silver powder 2: spherical silver powder (D50: 1 占 퐉)

Carbon black: # 4400 (manufactured by Tokai Carbon Co., Ltd.)

Ketchen Black: Ketchen ECP600JD manufactured by Lion Corporation

Graphite powder: Graphite BF manufactured by Chuetsu Graphite Industry Co., Ltd.

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

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

Leveling agent: MK &lt; RTI ID = 0.0 &gt;

Dispersant 1: Disperbyk 130 (trade name, manufactured by Big Chem Japan Co., Ltd.)

Dispersing agent 2: Disperbyk 2155 manufactured by Big Chem Japan Co., Ltd.

Dispersant 3: Disperbyk 180 (trade name, manufactured by Big Chem Japan Co., Ltd.)

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

Additive 2: NIR-AM1 manufactured by Nagase Chemtex Co., Ltd.

Additive 3: Light Acrylate PE-3A (pentaerythritol triacrylate) manufactured by Kyoeisha Chemical Co.,

EDGAC: Ethyldiglycol acetate (manufactured by Daicel Co., Ltd.)

BMGAC: butyl glycol acetate (manufactured by Daicel Co., Ltd.)

BDGAC: butyl diglycol acetate manufactured by Daicel Co.

TPOL: Tapinol manufactured by Nippon Terpene Chemical Co., Ltd.

Comparative Example 1

Laurylcarboxylic acid (1000 g) and butylamine (480 g) were dissolved in toluene (10 L). Subsequently, formic acid (150 g) was added dropwise, and the mixture was stirred at room temperature for 1.5 hours. When a large amount of methanol was added, the agglomerates of the silver nanoparticles precipitated and decanted. The decantation was repeated three times, and the precipitate was dried under reduced pressure. Subsequently, 1,000 g of the obtained precipitate (920 g of which was carboxylic acid amine complex 80 g) was redispersed in 1860 g of tapineol to obtain a conductive paste containing silver nanoparticles (silver sulfate 3). The obtained silver powder 3 had a particle diameter of about 10 nm from a transmission electron micrograph. The solid content concentration of the conductive paste was 35 mass%. Using the obtained conductive paste, a conductive laminate test piece and a laser etching processability evaluation test piece were prepared in the same manner as in Example, and evaluated in the same manner as in Example. The evaluation results are shown in Table 7. The conductivity of the present paste was such that the paste composition was significantly inferior in physical properties of the initial coating film, and in particular, lacked in adhesion, so that it could not withstand practical use.

Comparative Example 2

Dodecylamine was dissolved in tapainol to prepare a solution having a solid content concentration of 12% by weight. This solution was 1,000 parts, silver powder 4 (solid 120 parts by weight) (spherical silver powder (D50 = 1 ㎛) the 8083 portion, and a bead mill, a glass frit pulverized to an average particle size of 1.5 ㎛ ((bismuth oxide (Bi ₂ O ₃₎ (Bismuth oxide content: 80.0 to 99.9%) as a main component was added, and the mixing was continued. After homogenizing, the solution was dispersed with a three-roll mill to prepare a glass frit-containing conductive paste. The evaluation results are shown in Table 7. The conductive silver paste of the present invention was prepared in the same manner as in Example 1 except that the paste composition was used for the initial application The film properties were remarkably inferior, particularly the adhesiveness was insufficient, and it was not able to withstand practical use. Further, the laser etching workability was significantly poor, The width of the coating film having a much wider width than that of the laser beam irradiated in the range of &quot; a &quot;,&quot; a &quot;

Industrial availability

INDUSTRIAL APPLICABILITY The conductive paste for laser etching of the present invention can provide an electroconductive thin film excellent in reliability in wet heat and environment and capable of maintaining the durability of the coating film as the conductive thin film while maintaining suitability for laser etching processing, And is useful as a conductive paste for use in a touch panel mounted on an electronic book or the like.

1a, 2a, 3a, 4a: terminals 1a, 2a, 3a, 4a
1b, 2b, 3b, 4b: thin lines 1b, 2b, 3b, 4b
1c, 2c, 3c, 4c: terminals 1c, 2c, 3c, 4c
5: Evaluation of suitability for laser etching processing A pattern

Claims (12)

1. A conductive paste for laser etching comprising a binder resin (A), a metal powder (B), and an organic solvent (C) containing a thermoplastic resin. The conductive paste for laser etching according to claim 1, wherein the binder resin (A) is a thermoplastic resin having a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of 60 to 100 占 폚. The positive resist composition according to claim 1 or 2, wherein the binder resin (A) is a mixture of one or more kinds selected from the group consisting of a polyester resin, a polyurethane resin, an epoxy resin, a vinyl chloride resin, Wherein the conductive paste is a conductive paste for laser etching. 3. A method according to claim 1 or 2, wherein the binder resin (A), an acid value of 50 to 300 equivalents / 10 ⁶ g of polyester resin, and an acid value of 50 to 300 equivalents / 10 ⁶ g of polyester selected from the group consisting of a urethane resin Wherein the conductive paste is a mixture of two or more of the conductive paste. The conductive paste for laser etching according to any one of claims 1 to 4, further comprising a laser ray absorbent (D). An electroconductive thin film formed from the electroconductive paste for laser etching according to any one of claims 1 to 5. The conductive laminate according to claim 6, wherein the conductive thin film and the substrate are laminated. The conductive laminate according to claim 7, wherein the substrate has a transparent conductive layer. An electric circuit using the conductive thin film according to claim 6 or the conductive laminate according to claim 7 or 8. An electric circuit having a wiring portion formed by irradiating a part of the conductive thin film according to claim 6 with a laser beam selected from a carbonic acid 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 9 to 11 as a constituent member.

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