KR102007129B1 - Conductive paste for laser etching, conductive thin film, and conductive laminate - Google Patents

Abstract

(Problem) The present invention provides a conductive paste for laser etching processing, which is suitable for laser etching processing in which high density electrode circuit wiring having a L / S of 50/50 μm or less, which is difficult to cope with conventional screen printing methods, can be produced at low cost and low environmental load. do.
(Solution means) A conductive paste for laser etching processing containing a binder resin (A), a metal powder (B) and an organic solvent (C) containing a thermoplastic resin, a conductive thin film formed by using the conductive paste, an electrically conductive laminate, and an electric Circuit and touch panel.

Description

Conductive Paste, Conductive Thin Film, and Conductive Laminate for Laser Etching Processing {CONDUCTIVE PASTE FOR LASER ETCHING, CONDUCTIVE THIN FILM, AND CONDUCTIVE LAMINATE}

This invention relates to the manufacturing method of the conductive pattern which can manufacture the conductive pattern with high arrangement density in a planar direction, and the electrically conductive paste which can be used suitably for this manufacturing method. The electroconductive pattern of this invention is typically used for the electrode circuit wiring of a transparent touch panel.

In recent years, the high performance and miniaturization of the electronic device which mounts the transparent touch panel represented by a mobile telephone, a notebook, an electronic book, etc. are progressing rapidly. In order to increase the performance and miniaturization of these electronic devices, in addition to miniaturization, high performance, and integration of electronic components to be mounted, there is a demand for higher density of electrode circuit wiring for joining these electronic components. In addition to the resistive film method with a small number of electrode circuit wirings as a method of the transparent touch panel, the spread of the capacitive method with a large number of electrode circuit wirings has been rapidly progressing in recent years. have. In addition, in order to make the display screen larger, there is a demand to narrow the frame portion in which the electrode circuit wiring is arranged due to the demands on the product design, and from such a viewpoint, the densification of the electrode circuit wiring is required. In order to satisfy the above requirements, the technique which can perform the high density arrangement of the electrode circuit wiring more than conventionally is calculated | required.

The arrangement density of the electrode circuit wirings in the frame portion of the resistive transparent touch panel is about 200 µm or more in the plane direction of the line and space in the plane direction (hereinafter abbreviated as L / S = 200/200 µm). It is conventionally performed to form this by screen printing of an electrically conductive paste. In the capacitive touch panel, the L / S requirement is about 100/100 μm or less, and the L / S may be required to be 50/50 μm or less. Has become a difficult situation to respond to.

The photolithography method is mentioned as an example of a candidate of the electrode circuit wiring formation technique which replaces screen printing. If the photolithography method is used, it is also possible to form a thin wire having an L / S of 50/50 µm or less. However, there is also a problem in the photolithography method. The most typical example of the photolithography method is a method using a photosensitive resist. Generally, a photosensitive resist is applied to a copper foil portion of a surface substrate on which a copper foil layer is formed, and a desired pattern is obtained by a method such as direct drawing of a photomask or a laser beam. Is exposed, and the photosensitive resist is developed, and the copper foil thin line pattern is formed by melt | dissolving and removing copper foil parts other than a desired pattern with chemical | medical agent after that. For this reason, the environmental load by waste liquid treatment is large, and a process is cumbersome, and there exist many subjects including a viewpoint of a production efficiency and a volume.

<< prior art document >>

(Patent Document 1) Patent Document 1: Japanese Unexamined Patent Publication No. 2010-237573

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

An object of the present invention is to provide a manufacturing method 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 a screen printing method, at low cost and with low environmental load. Moreover, it is providing the electrically conductive paste which can be used suitably for such a manufacturing method.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining the manufacturing method which arrange | positions an electrode circuit wiring at high density in a planar direction, the layer which consists of a binder resin and electrically conductive powder is formed on an insulating base material, and a part of this is made into an insulating base material by a laser beam irradiation. By removing the phase, it was found that a high-density electrode circuit wiring having a L / S of 50/50 µm or less, which is difficult to realize by the screen printing method, can be manufactured. Moreover, the electrically conductive paste suitable for forming the layer containing binder resin and electrically conductive powder suitable for such a manufacturing method was found. That is, this invention includes the following structures.

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

(2) The conductive paste for laser etching processing 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 ° C.

(3) The binder resin (A) is one or a mixture of two or more selected from the group consisting of polyester resins, polyurethane resins, epoxy resins, vinyl chloride resins and fibrin derivative resins (1) Or the electrically conductive paste for laser etching processes as described in (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 It is a mixture, The electrically conductive paste for laser etching processes as described in (1) or (2).

(5) The conductive paste for laser etching processing according to any one of (1) to (4), further comprising a laser light absorbing agent (D).

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

(7) The electroconductive laminated body by which the electroconductive thin film and base material as described in (6) are laminated | stacked.

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

(9) An electric circuit formed by using the conductive thin film as described in (6) or the conductive laminate as described in (7) or (8).

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

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

(12) The touch panel which contains the electrical circuit in any one of (9)-(11) as a structural member.

The electrically conductive paste of this invention is an electrically conductive paste containing binder resin (A), a metal powder (B), and an organic solvent (C) containing a thermoplastic resin, and by taking such a structure, it is excellent in laser etching processability, Moreover, even after a laser etching process, the electroconductive thin film excellent in the adhesiveness after the initial stage and wet heat environment load with respect to a base material can be formed. Here, the laser etching processability is excellent, when at least a part of the conductive thin film is peeled off from the substrate by a laser etching process to form a thin wire of about L / S = 30/30 μm, 1) between both ends of the thin wire It means to satisfy the 3 conditions of conduction to be secured, 2) insulation between adjacent fine wires, and 3) good fine wire shape. Moreover, since the electrically conductive paste containing the laser beam absorber (D) which is embodiment of this invention becomes more sensitive to laser beam irradiation than the electrically conductive paste containing no laser beam absorber (D), the improvement of a laser scanning speed, It also exhibits a further superior effect of reducing the laser output.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the pattern which irradiates a laser beam to the laser etching processability evaluation test piece used by the Example and comparative example of this invention. Laser light is irradiated to the white site, and the conductive thin film formed on the substrate is removed. The laser beam is not irradiated to the halftone spot. The unit of the dimension display in a figure is mm.

<< component >> which comprises the electrically conductive paste of this invention

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

<Binder Resin (A)>

The kind of binder resin (A) is not particularly limited as long as it is a thermoplastic resin, but polyester resin, epoxy resin, phenoxy resin, polyamide resin, polyamideimide resin, polycarbonate resin, polyurethane resin, phenol resin, acrylic resin, Polystyrene, styrene-acrylic resin, styrene-butadiene copolymer, phenol resin, polyethylene resin, polycarbonate resin, phenol resin, alkyd resin, styrene-acrylic resin, styrene-butadiene copolymer resin, polysulfone resin, polyether sulfone resin And vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer, polystyrene, silicone resin, fluorine resin, and the like, and these resins may be used alone or as a mixture of two or more thereof. It is preferable that it is 1 type, or 2 or more types of mixtures chosen from the group which consists of a polyester resin, a polyurethane resin, an epoxy resin, a vinyl chloride resin, and a cellulose derivative resin. Among these resins, a polyurethane resin (hereinafter sometimes referred to as a polyester polyurethane resin) containing a polyester resin and / or a polyester component as a copolymerization component 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 that the degree of freedom in molecular design is high. By selecting the dicarboxylic acid and glycol component constituting the polyester resin, the copolymerization component can be freely changed, and the provision of a functional group to the molecular chain or to the molecular terminal is also easy. For this reason, the characteristics of resin, such as the glass transition temperature of the polyester resin obtained, affinity with the other component mix | blended with a base material, and an electrically conductive paste, can be adjusted suitably.

Examples of the dicarboxylic acid that can be used as a copolymerization component of the polyester resin used as the binder resin (A) in the present invention include aromatics such as terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid. Aliphatic dicarboxylic acids such as dicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, azelaic acid, dicarboxylic acid, etc. Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydro Alicyclic dicarboxylic acids, hydrides such as phthalic anhydride, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalenedicarboxylic acid, tricyclodecanedicarboxylic acid Oxybenzoic acid, milk And hydroxycarboxylic acids such as acid. Moreover, in the range which does not impair the effect of this invention, trivalent or more carboxylic acids, such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids, such as fumaric acid, and / or sodium 5-sulfoisophthalate You may use together sulfonic-acid metal base containing dicarboxylic acid, such as a salt, as a copolymerization component.

Examples of the polyol which can be used as a 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, neopentylglycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2,2 Aliphatic diols such as diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol, and 1,4-cyclohexane Alicyclic diols such as dimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, dimerdiol, and the like. Moreover, you may use together a trivalent or more polyol, such as trimethylol ethane, a trimethylol propane, a glycerin, pentaerythritol, and a polyglycerol, as a copolymerization component in the range which does not impair the effect of this invention.

As for the polyester resin used as binder resin (A) in this invention, in terms of durability, such as intensity | strength, heat resistance, moisture resistance, and thermal shock resistance, aromatic dicarboxylic acid is mentioned among the computer components which comprise the said polyester resin. It is preferable to copolymerize 60 mol% or more, More preferably, it is 80 mol% or more, More preferably, it is 90 mol% or more, Especially preferably, it is 98 mol% or more. It is a preferred embodiment that the computing component comprises an aromatic dicarboxylic acid. When the copolymerization ratio of an aromatic dicarboxylic acid component is too low, the glass transition temperature of the polyester resin obtained will become lower than 60 degreeC, and there exists a tendency for the moisture heat resistance and durability of the electroconductive thin film obtained to fall.

The polyester resin used as the binder resin (A) in the present invention has 4 carbon atoms in the main chain of all the polyols constituting the polyester resin in view of durability, such as strength, heat resistance, moisture resistance, and thermal shock resistance. It is preferable that the following glycol is 60 mol% or more, It is more preferable that it is 80 mol% or more, It is further more preferable that it is 95 mol% or more. When 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 polyurethane resin obtained becomes lower than 60 ° C, and the heat and moisture resistance and durability of the resulting conductive thin film tend to be lowered.

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, the polyurethane resin also has a glass transition temperature by selecting an appropriate component as a copolymerization component constituting the polyurethane resin and providing a functional group to the molecular chain or to the molecular terminal. The properties of the resin such as affinity with other components blended with the base material and the conductive paste can be appropriately adjusted.

Although it does not specifically limit also about the copolymerization component of a polyurethane resin, It is preferable that it is a polyester polyurethane resin which uses a polyester polyol as a copolymerization component from a viewpoint of freedom of design, heat-and-moisture resistance, and durability maintenance. As a suitable example of the said polyester polyol, what is a polyol among the polyester resins which can be used as binder resin (A) in this invention mentioned above is mentioned.

The polyurethane resin used as binder resin (A) in this invention can be obtained by reaction of a polyol and polyisocyanate, for example. As polyisocyanate which can be used as a copolymerization component of the said polyurethane resin, 2, 4- tolylene diisocyanate, 2, 6- tolylene diisocyanate, p-phenylenedi isocyanate, 4,4'- diphenylmethane diisocyanate, m -Phenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, 2,6-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylenediisocyanate, 4, 4'-diphenylene diisocyanate, 4,4'- diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, m-xylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, toluenedi Isocyanate etc. are mentioned and any of aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate may be sufficient. Moreover, you may use together a trivalent or more isocyanate compound as a copolymerization component in the range which does not impair the effect of this invention.

In the polyurethane resin used as binder resin (A) in this invention, the compound which has a functional group which can react with an isocyanate can be copolymerized as needed. As a functional group which can react with an isocyanate, a hydroxyl group and an amino group are preferable, and may have either, or may have both. Specific examples thereof include dimethylol butanoic acid, dimethylol propionic acid, 1,2-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2,2-dimethyl- 1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2-dimethyl- 3-hydroxypropyl-2 ', 2'-dimethyl-3'-hydroxypropanoate, 2-normalbutyl-2-ethyl-1,3-propanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol, 3-phenyl-1,5-pentanediol, 2,5 Compound which has two hydroxyl groups in 1 molecule, such as -dimethyl-3- sodium sulfo-2, 5- hexanediol and dimerdiol (for example, PRIPOOL-2033 by Unichema International Co., Ltd.), trimethylol ethane, and trimethylol propane Alcohols having three or more hydroxyl groups in one molecule such as glycerin, pentaerythritol, polyglycerin, monoethanolamine, diethanolamine, Amino alcohol, ethylenediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1 having one or more hydroxyl groups and amino groups in one molecule such as ethanolamine Aliphatic diamines such as, 11-undecanediamine and 1,12-dodecanediamine, methacrylene diamine, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, 4,4'- The compound which has two amino groups in 1 molecule, such as aromatic diamine, such as diamino diphenyl ether, is mentioned. The compound which has a functional group which can react with 2 or more isocyanate in 1 molecule of said number average molecular weight less than 1,000 may be used independently, or there is no problem at all using it together.

Although the number average molecular weight of binder resin (A) in this invention is not specifically limited, It is preferable that number average molecular weights are 5,000-60,000. If the number average molecular weight is too low, it is not preferable in view of durability and moisture-heat resistance of the formed conductive thin film. On the other hand, when the number average molecular weight is too high, the cohesion force of the resin increases and the durability as the conductive thin film is improved, but the laser etching processability is significantly deteriorated.

It is preferable that it is 60 degreeC or more, and, as for the glass transition temperature of binder resin (A) in this invention, it is more preferable that it is 65 degreeC or more. When the glass transition temperature is low, the laser etching processability may be improved, but there is a fear that the wet heat environmental reliability as the conductive thin film may be lowered, and the surface hardness may be lowered and the adhesiveness may be caused during the manufacturing process and / or use. There exists a possibility that transfer of the paste containing component to a contact counterpart may generate | occur | produce, and electroconductive thin film reliability may fall. On the other hand, when the glass transition temperature of the binder resin (A) used for this invention considers printability, adhesiveness, solubility, paste viscosity, a laser etching processability, etc., 150 degrees C or less is preferable, and 120 degrees C or less is more preferable. And 100 degrees C or less is more preferable.

Although the acid value of binder resin (A) in this invention is not specifically limited, The adhesiveness with respect to a base material can be remarkably improved by having an acid value of a specific range. At the time of laser etching of a conductive thin film, the temperature around the laser irradiation site | part may rise and the adhesiveness of a conductive thin film and a base material may fall, but by using binder resin which has an acid value of a specific range as binder resin (A), And the fall of adhesiveness may be suppressed. It is preferable that it is 50-350 eq / ton, and, as for the acid value of binder resin (A), it is more preferable that it is 100-250 eq / ton. When the acid value is too low, there is a tendency for the adhesion between the conductive thin film to be formed and the substrate to be lowered. On the other hand, when the acid value is too high, the absorbency of the conductive thin film to be formed increases, and there is a possibility that the hydrolysis of the binder resin may be promoted by the catalytic action of the carboxyl group, leading to a decrease in the reliability of the conductive thin film.

<Metal powder (B)>

As metal powder (B) used for this invention, precious metal powders, such as silver powder, gold powder, platinum powder, palladium powder, copper powder, nickel powder, nonmetal powder, such as aluminum powder, brass powder, precious metals, such as silver And nonmetal powder powdered or alloyed. These metal powders may be used independently and may be used together. Among these, in consideration of conductivity, stability, cost and the like, it is preferable to use silver powder alone or silver powder as the main component.

The shape of the metal powder (B) used for this invention is not specifically limited. Examples of the shape of a conventionally known metal powder include a flake type (flake type), a spherical shape, a twig type (dendrite type), and a spherical primary particle described in Japanese Patent Laid-Open No. 9-306240. There are dimensional aggregates (aggregates) and the like, and among them, spherical, aggregated and flake metal powders are preferably used.

It is preferable that the center diameter (D50) of the metal powder (B) used for this invention is 4 micrometers or less. There exists a tendency for the thin wire shape of a laser etching process site | part to become favorable by using the metal powder (B) whose center diameter is 4 micrometers or less. When the metal powder with a central diameter larger than 4 micrometers is used, the thin wire shape after a laser etching process will worsen, and as a result, a thin wire may contact and may cause a short circuit. In addition, in the laser etching process, there exists a possibility that the conductive thin film which peeled and removed once may adhere to a process site | part again. The lower limit of the center diameter of the metal powder (B) is not particularly limited. However, the center diameter is preferably 80 nm or more because it is easy to aggregate when the cost point and the particle diameter becomes fine, and consequently, the dispersion becomes difficult. If the central diameter is smaller than 80 nm, the cohesion force of the metal powder increases, and the laser etching processing titration deteriorates, which is not preferable from the viewpoint of cost.

In addition, center diameter D50 means the particle diameter (micrometer) whose cumulative value becomes 50% in the cumulative distribution curve (volume) obtained by some measuring method. In the present invention, the cumulative distribution curve is measured in the total reflection mode using a laser diffraction scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., MICROTRAC HRA).

From a viewpoint that the electroconductivity of the formed conductive thin film is favorable, 400 mass parts or more are preferable with respect to 100 mass parts of thermoplastic resin (A), and, as for content of metal powder (B), 560 mass parts or more are more preferable. Moreover, from a viewpoint that content of (B) component is favorable in adhesiveness with a base material, 1,900 mass parts or less are preferable with respect to 100 mass parts of thermoplastic resin (A), and 1,230 mass parts or less are more preferable.

<Organic Solvent (C)>

Although the organic solvent (C) which can be used for this invention is not specifically limited, From a viewpoint which keeps the volatilization rate of an organic solvent in an appropriate range, it is preferable that boiling point is 100 degreeC or more and less than 300 degreeC, More preferably, it is a boiling point It is 150 degreeC or more and less than 280 degreeC. 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 in a three roll mill or the like as necessary, and at that time, If the boiling point is too low, the solvent may volatilize during dispersion and the component ratio constituting the conductive paste may change. On the other hand, when the boiling point of an organic solvent is too high, there exists a possibility that a solvent may remain in a large amount in a coating film depending on dry conditions, and there exists a possibility of causing the fall of the reliability of a coating film.

Moreover, as an organic solvent (C) which can be used for this invention, it is preferable that a thermoplastic resin (A) is soluble and can disperse | distribute a metal powder (B) favorably. Specific examples include ethyl diglycol acetate (EDGAC), butyl glycol acetate (BMGAC), butyl diglycol acetate (BDGAC), cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, and exon chemicals. Solvetso 100, 150, 200, propylene glycol monomethyl ether acetate, adipic acid, a mixture of dimethyl esters of succinic acid and glutaric acid (e.g., DBE manufactured by DuPont Co., Ltd.), tapionel, and the like can be mentioned. Among them, EDGAC, BMGAC, BDGAC and mixtures thereof from the viewpoint of excellent solubility of the blending component of the thermoplastic resin (A), good solvent volatility during continuous printing, and good suitability for printing by screen printing or the like. Solvents are preferred.

As content of the organic solvent (C), it is preferable that they are 5 weight part or more and 40 weight part or less with respect to 100 weight part of paste total weight, and it is more preferable that they are 10 weight part or more and 35 weight part or less. When content of the organic solvent (C) is too high, paste viscosity will become low too much and there exists a tendency which becomes easy to produce sagging at the time of fine wire printing. On the other hand, when the content of the organic solvent (C) is too low, the viscosity as a paste becomes very high, and for example, the screen printability at the time of forming the conductive thin film remarkably decreases, and the film thickness of the formed conductive thin film becomes thick, and the laser Etch processability may fall.

<Laser light absorber (D)>

You may mix | blend a laser beam absorber (D) with the electrically conductive paste of this invention. The laser beam absorber (D) refers to an additive having strong absorption in the wavelength of the laser beam, and the laser beam absorbent (D) itself may be either conductive or nonconductive. For example, when using the YAG laser whose wavelength of a fundamental wave is 1064 nm as a light source, the dye and / or pigment which have strong absorption in wavelength 1064 nm can be used as a laser beam absorber (D). By mix | blending a laser beam absorbent (D), the electroconductive thin film of this invention absorbs a laser beam with high efficiency, the volatilization and thermal decomposition of the binder resin (A) by heat generation are accelerated | stimulated, and a laser etching processability improves as a result.

As an example of what has electroconductivity among the laser beam absorbents (D) which can be used for this invention, carbon-based fillers, such as carbon black and graphite powder, are mentioned. The compounding of the carbon-based filler also has the effect of enhancing the conductivity of the conductive thin film of the present invention. However, since carbon black has an absorption wavelength in the vicinity of 1060 nm, for example, a laser beam having a wavelength of 1064 nm, such as a YAG laser or a fiber laser, is used. Irradiation of the conductive thin film absorbs the laser light with high efficiency, so that the sensitivity to the laser light irradiation is increased, so that even when the scanning speed of the laser irradiation is increased and / or when the laser light source is low power, good laser etching processing aptitude is obtained. You can expect the effect. As content of the said carbon-type filler, it is preferable that it is 0.1-5 weight part with respect to 100 weight part of metal powder (B), and it is more preferable that it is 0.3-2 weight part. When the blending ratio of the carbon-based filler is too low, the effect of increasing the conductivity and the effect of increasing the sensitivity to laser light irradiation are small. On the other hand, when the blending ratio of the carbon-based filler is too high, the conductivity of the conductive thin film tends to be lowered, and the resin may be adsorbed to the void portion of the carbon, resulting in a problem that the adhesion to the substrate is lowered. .

Among the laser light absorbers (D) that can be used in the present invention, examples of the nonconductive ones include conventionally known dyes, pigments, and infrared absorbers. More specifically, azo dye, metal complex salt azo dye, pyrazolone azo dye, naphthoquinone dye, anthraquinone dye, phthalocyanine dye, carbonium dye, quinone imine dye, methine dye, cyanine dye, squarylium pigment, pyril As dyes and pigments, such as a cerium salt and a metal thiolate complex, 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, the other, a polymer binding pigment Can be mentioned. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, Isoindolinone pigments, quinophthalone pigments, dyeing 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, which is an infrared absorber of dimonium salt type, and NIR-AM1 (all manufactured by Nagase Chemtex Co., Ltd.) of an aluminum salt type. These nonconductive laser light absorbers (D) preferably contain 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight. When the compounding ratio of a nonelectroconductive laser beam absorber (D) is too low, the effect which raises the sensitivity with respect to laser beam irradiation is small. When the compounding ratio of a nonelectroconductive laser beam absorber (D) is too high, there exists a possibility that the electroconductivity of a conductive thin film may fall, and the color tone of a laser beam absorber may become remarkable, and it may be undesirable depending on a use.

The following inorganic substance can be added to the electrically conductive paste of this invention. 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 borides such as various nitrides such as boron nitride, titanium nitride and zirconium nitride, and zirconium boride; Various oxides such as titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica and colloidal silica; Various titanate 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; Others, talc, bentonite, talc, calcium carbonate, kaolin, glass fibers, mica and the like can be used. By adding these inorganic substances, it may become possible to improve printability, heat resistance, and also mechanical characteristics and long-term durability. Especially, in the electrically conductive paste of this invention, a silica is preferable from a viewpoint of providing durability, printing aptitude, especially screen printing aptitude.

In addition, a thixotropic imparting agent, an antifoamer, a flame retardant, a tackifier, a hydrolysis inhibitor, a leveling agent, a plasticizer, antioxidant, a ultraviolet absorber, a flame retardant, a pigment, and a dye can be mix | blended with the electrically conductive paste of this invention. Moreover, carbodiimide, an epoxy, etc. can also be mix | blended suitably as a resin decomposition inhibitor. These may be used alone or in combination.

<Hardener (E)>

You may mix | blend the hardening | curing agent which can react with binder resin (A) to the electrically conductive paste of this invention to the extent which does not impair the effect of this invention. By mix | blending a hardening | curing agent, although hardening temperature may increase and the load of a production process may increase, the improvement of the moisture-heat resistance of a coating film can be anticipated by crosslinking by the heat which arises at the time of coating film drying or laser etching.

Although the kind of hardening | curing agent which can react with the binder resin (A) of this invention is not limited, The isocyanate compound is especially preferable from adhesiveness, bending resistance, curability, etc. Moreover, when these isocyanate compounds use what blocked the isocyanate group, storage stability improves and it is preferable. As hardening agents other than an isocyanate compound, well-known compounds, such as amino resin, such as methylated melamine, butylated melamine, benzoguanamine, and urea resin, an acid anhydride, imidazole, an epoxy resin, and a phenol resin, are mentioned. In these hardening | curing agents, the well-known catalyst or promoter chosen according to the kind can also be used together. As a compounding quantity of a hardening | curing agent, it mix | blends to the extent which does not impair the effect of this invention, Although it does not restrict | limit especially, 0.5-50 mass parts is preferable with respect to 100 mass parts of binder resin (A), and 1-30 mass parts is more Preferably, 2-20 mass parts is more preferable.

As an example of the isocyanate compound which can be mix | blended with the electrically conductive paste of this invention, there exist aromatic or aliphatic diisocyanate, trivalent or more polyisocyanate, etc., Any of a low molecular weight compound and a high molecular compound may be sufficient. For example, aromatic diisocyanates, such as aliphatic diisocyanate, such as tetramethylene diisocyanate and hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, Alicyclic diisocyanates such as dimer diisocyanate, isophorone diisocyanate, or trimers of these isocyanate compounds, and excess amounts of these isocyanate compounds, such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, mono Low molecular weight active hydrogen compounds such as ethanolamine, diethanolamine and triethanolamine, or polymer active hydrogen compounds of various polyester polyols, polyether polyols and polyamides, etc. It can be obtained by a terminal isocyanate group-containing compound. Moreover, as a blocking agent of an isocyanate group, For example, Phenols, such as a phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, chlorophenol; Oximes such as acetoxime, methyl ethyl keto oxime and cyclohexanone oxime; Alcohols such as methanol, ethanol, propanol and butanol; Halogen-substituted alcohols such as ethylene chlorhydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol; and lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam, and other aromatic amines, imides, acetylacetone, acetic acid ester, and malonic acid ethyl ester. And other active methylene compounds, mercaptans, imines, imidazoles, urea, diaryl compounds, sodium bisulfite, and the like. Among them, oximes, imidazoles, and amines are particularly preferable in view of curability.

<< physical property required for the electrically conductive paste of this invention >>

As for the electrically conductive paste of this invention, it is preferable that F value is 60 to 95%, More preferably, it is 75 to 95%. F value is a numerical value which shows the filler mass part with respect to 100 mass parts of total solids contained in a paste, and is represented by F value = (filler mass part / solid content mass part) x100. The filler mass part here is the mass part of electroconductive powder, and solid content mass part is the mass part of components other than a solvent, and contains all electroconductive powder, binder resin, another hardening | curing agent, and an additive. When F value is too low, the electroconductive thin film which shows favorable electroconductivity will not be obtained, and when F value is too high, the adhesiveness of a conductive thin film and a base material, and / or the surface hardness of a conductive thin film will fall, and printability fall also cannot be avoided. In addition, electroconductive powder refers to both the electroconductive powder containing a metal powder (B) and a nonmetal here.

<< manufacturing method of the electrically conductive paste of this invention >>

As described above, 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 in three rolls or the like as necessary. Here, an example of a more specific manufacturing procedure is shown. The thermoplastic resin (A) is first dissolved in an organic solvent (C). Thereafter, the metal powder (B) and an additive are added as necessary, and preliminary dispersion is performed by a double planetary, a dissolver, a planetary stirrer, or the like. Then, it disperse | distributes with three roll mills and obtains an electrically conductive paste. The electrically conductive paste obtained in this way can be filtered as needed. Dispersion using other dispersers such as bead mills, kneaders, extruders and the like is not a problem at all.

<< conductive thin film, conductive laminated body of this invention, and manufacturing method thereof >>

The conductive thin film of this invention can be formed by apply | coating or printing the electroconductive paste of this invention on a base material, forming a coating film, then volatilizing the organic solvent (C) contained in a coating film, and drying a coating film. Although the method of apply | coating or printing a conductive paste on a base material is not specifically limited, Printing by the screen printing method is preferable at the point of the simplicity of a process, and the technique prevalent in the industry which forms an electric circuit using a conductive paste. In addition, it is preferable to apply | coat or print the electrically conductive paste to the site | part which is a little wider than the electrically conductive thin film site | part finally required as an electric circuit from a viewpoint of reducing the load of a laser etching process and forming the electric circuit of this invention efficiently.

As a base material which apply | coats the electrically conductive paste of this invention, the material excellent in dimensional stability is used preferably. For example, the film containing the material excellent in flexibility, such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, or polycarbonate, is mentioned. Moreover, inorganic materials, such as glass, can also be used as a base material. Although the thickness of a base material is not specifically limited, It is preferable that it is 50-350 micrometers, and 100-250 micrometers is more preferable from the mechanical characteristic, shape stability, handleability, etc. of a pattern forming material.

Moreover, the adhesiveness of a conductive thin film and a base material can be improved by performing physical treatment and / or chemical treatment on the surface of the base material apply | coating the electrically conductive paste of this invention. Examples of the physical treatment include a sand blast method, a wet blast method for injecting a liquid containing fine particles, a corona discharge treatment method, a plasma treatment method, an ultraviolet or vacuum ultraviolet irradiation treatment method, and the like. In addition, examples of the chemical treatment method include a strong acid treatment method, a strong alkali treatment method, an oxidizing agent treatment method and a coupling agent treatment method.

Moreover, the said base material may have a transparent conductive layer. The conductive thin film of this invention can be laminated | stacked on a transparent conductive layer. The raw material of the said transparent conductive layer is not specifically limited, For example, the ITO membrane which consists of indium tin oxide as a main component is mentioned. In addition, the transparent conductive layer may not only be formed on the entire surface of the substrate, but also may be used in which a part of the transparent conductive layer is removed by etching or the like.

It is preferable to perform the process which volatilizes an organic solvent (C) under normal temperature and / or heating. When heating, since the electroconductivity, adhesiveness, and surface hardness of the conductive thin film after drying become favorable, 80 degreeC or more is preferable, 100 degreeC or more is more preferable, and 110 degreeC or more is more preferable. Moreover, from a viewpoint of the heat resistance of the transparent conductive layer which is a base, and energy saving in a production process, 150 degrees C or less is preferable, 135 degrees C or less is more preferable, and 130 degrees C or less is still more preferable. When the hardening | curing agent is mix | blended with the electrically conductive paste of this invention, when a process which volatilizes the organic solvent (C) is performed under heating, hardening reaction advances.

What is necessary is just to set the thickness of the electroconductive thin film of this invention to an appropriate thickness according to the use used. However, from the viewpoint of the good electrical conductivity of the conductive thin film after drying and the good laser etching processability, the thickness of the conductive thin film is preferably 3 μm or more and 30 μm or less, more preferably 5 μm or more and 20 It is micrometer or less. If the film thickness of the conductive thin film is too thin, there is a possibility that desired conductivity as a circuit cannot be obtained. If the film thickness is too thick, an excessive amount of irradiation required for laser etching processing may be required, which may damage the substrate. In addition, when the variation in the film thickness is large, variations occur in the ease of etching of the conductive thin film, and there is a tendency that short circuits between lines due to insufficient etching and disconnection due to excessive etching occur. For this reason, the change of film thickness should be small.

<< electrical circuit of this invention and its manufacturing method >>

In the site where the laser light is irradiated and absorbed, the energy of the laser light is converted into heat, pyrolysis and / or volatilization occurs due to the temperature rise, and the irradiation site is peeled off and removed. In order to remove the site | part irradiated with the laser beam of the conductive thin film of this invention efficiently from a base material, it is preferable that the conductive thin film of this invention has strong absorption in the wavelength of an irradiation laser beam. Therefore, as a laser species, it is preferable to select the laser species which has energy in the wavelength range in which the component which comprises the conductive thin film of this invention has strong absorption.

Common laser species include excimer laser (wavelength of fundamental wave 193-308 nm), YAG laser (wavelength of fundamental wave 1064 nm), fiber laser (wavelength of fundamental wave is 1060 nm), CO2 laser (of fundamental wave) 10600 nm in wavelength), a semiconductor laser, etc. are mentioned, There is no problem basically even if a laser species of any wavelength is used in any system. By selecting a laser species that matches the absorption wavelength region of any of the constituent components of the conductive thin film and which can irradiate a wavelength at which the substrate does not have strong absorption, the conductive thin film of the laser light irradiation site can be efficiently removed and the substrate Damage can be avoided. From such a viewpoint, as the laser species to be irradiated, the wavelength of the fundamental wave is preferably in the range of 532 to 10700 nm. For example, when using as a base material the polyester film, the transparent conductive laminated body which formed the ITO layer on the polyester film, or the laminated body in which the ITO layer was formed on the polyester film and one part was removed by the etching, It is particularly preferable to use a YAG laser or a fiber laser in that it does not damage the substrate well because the substrate does not have absorption in the wavelength of the fundamental wave.

Although the laser output and Q modulation frequency are not specifically limited, the conductive thin film of a laser beam irradiation site | part can be removed, and it adjusts so that a base base material may not be damaged. Generally, it is preferable to adjust a laser output suitably in the range of 0.5-100 W and Q modulation frequency 10-400 kHz. If the laser power 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 scanning speed of the laser or increasing the number of scanning. If the laser output is too high, the portion where the conductive thin film is peeled off due to diffusion of heat from the irradiated portion becomes extremely larger than the laser beam diameter, and the line width may be too thin or disconnected.

The scanning speed of a laser beam is so good that it is high from a viewpoint of the productive efficiency improvement by reduction of tact time, Specifically, 1000 mm / s or more is preferable, 1500 mm / s or more is more preferable, More preferably, 2000 mm / s or more. 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 the thermal history. Although the upper limit of a processing speed is not specifically determined, When a scanning speed is too high, removal of the conductive thin film of a laser beam irradiation site | part may become incomplete, and a circuit may short circuit. In addition, if the scanning speed is too fast, in the corner portion of the pattern to be formed, it is inevitable to reduce the scanning speed as compared with the linear portion, so that the thermal history of the corner portion is higher than that of the linear portion, and the laser of the corner portion is increased. There is a fear that the physical properties of the conductive thin film around the etching process site may be significantly reduced.

The scanning of the laser beam may be either of moving the projectile of the laser beam, moving of the irradiated object to which the laser beam is irradiated, or combining both, for example, by using the XY stage. The laser beam can also be scanned by changing the irradiation direction of the laser beam using a galvano mirror or the like.

At the time of irradiation of a laser beam, an energy density per unit area can be raised by using a condensing lens (achromatic lens or the like). As an advantage of this method, since the energy density per unit area can be increased as compared with the case of using a mask, laser etching processing can be performed at a high scanning speed even with a small output laser oscillator. have. When irradiating the collected laser light to the conductive thin film, it is necessary to adjust the focal length. In particular, the focal length needs to be adjusted depending on the film thickness applied to the substrate, but it is preferable to adjust the focal length so as not to damage the substrate and to remove and remove a predetermined conductive thin film pattern.

Repeating scanning of a laser beam in the same pattern a plurality of times is one of the preferred embodiments. Even when there is a conductive thin film portion which is incompletely removed in the first scan, or when a component constituting the removed conductive thin film is attached to the substrate again, the conductive thin film of the laser light irradiation portion can be completely removed by a plurality of scans. Become. Although the upper limit of the frequency | count of scanning is not specifically limited, Caution is necessary because the periphery of a process part may receive a heat history multiple times, and may be damaged, discolored, or a coating film physical property may fall. In addition, in view of production efficiency, it is natural that the smaller the number of injections, the better.

It is also one of the preferred embodiments that the laser beam is not repeatedly scanned in the same pattern a plurality of times. Unless adversely affects the characteristics of the obtained conductive thin film, the conductive laminate and the electrical circuit, it is natural that the fewer the number of scanning is, the more excellent the production efficiency is.

<< touch panel of this invention >>

The electroconductive thin film, electroconductive laminated body, and / or electric circuit of this invention can be used as a structural member of a touchscreen. The touch panel may be a resistive film type or a capacitive type. Although it is applicable to any touch panel, since this paste is suitable for thin wire formation, it can be used especially suitably for the electrode wiring of a capacitive touch panel. Moreover, as a base material which comprises the said touchscreen, it is preferable to use the base material which has transparent conductive layers, such as an ITO film | membrane, or the base material in which these were removed partially by etching.

Example

In order to demonstrate this invention further in detail, an Example and a comparative example are given to the following, but this invention is not limited at all by the Example. In addition, each measured value described in the Example and the comparative example is 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% by weight, and filtered with a membrane filter made of polytetrafluoroethylene having a pore diameter of 0.5 µm to obtain a GPC measurement sample. Using tetrahydrofuran as a mobile phase and using a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation, using a differential refractometer (RI system) as a detector, the resin sample was subjected to a column temperature of 30 ° C. and a flow rate of 1 ml / min. GPC measurement was performed. In addition, the number average molecular weight was made into the standard polystyrene conversion value, and was computed by omitting the part corresponding to less than 1000 molecular weight. The GPC column used shodex KF-802, 804L, and 806L by Showa Denko Corporation.

2. Glass transition temperature (Tg)

5 mg of sample resin was put in an aluminum sample pan and sealed, and measured using a differential scanning calorimetry (DSC) DSC-220 manufactured by Seiko Instruments Co., Ltd. It calculated | required by the temperature of the intersection of the extension line of the baseline below transition temperature, and the tangent which shows the largest inclination in a transition part.

3. Acid value

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

5. Paste Viscosity

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

6. Storage stability of conductive paste

The electrically conductive paste was put into the poly container, and the sealed thing was stored for 1 month at 40 degreeC. After storage, a viscosity measurement and a test piece produced by the 5. conductive laminate test piece were evaluated.

(Circle): There is no remarkable viscosity change, and initial stage specific resistance, pencil hardness, and adhesiveness are maintained.

X: The remarkable viscosity rise (2 times or more of initial viscosity) or the remarkable viscosity fall (half or less of initial viscosity), and / or the fall of specific resistance, pencil hardness, and / or adhesiveness are confirmed.

7. Preparation of conductive laminate test pieces

Each of PET film (Lumira S made by Toraya Corporation) and ITO film (KH300, made by Oike Industries Co., Ltd.) with an annealing treatment having a thickness of 100 µm was used for screen printing using a 200-mesh polyester screen. The conductive paste was printed to form a solid coating pattern having a width of 25 mm and a length of 450 mm, and then heated at 120 ° C. for 30 minutes in a hot air circulation drying furnace to form a conductive laminate test piece. Moreover, the coating thickness at the time of printing was adjusted so that dry film thickness might be 6-10 micrometers.

8. Adhesiveness

Using the said electroconductive laminated body test piece, it evaluated by the peeling test using the cello tape (trademark) (made by Nichiban Co., Ltd.) according to JISK-5400-5-6: 1990. In addition, the number of cuts in each direction of the grid pattern was 11, and the cut space | interval was 1 mm. 100/100 indicates good adhesion without peeling, and 0/100 indicates that all peeled off.

9. Resistivity

The sheet resistance and film thickness of the said electroconductive laminated body test piece were measured, and the specific resistance was computed. The film thickness used gauge stand ST-022 (made by Onosoki Co., Ltd.), measured the thickness of 5 times of cured coating films using the thickness of PET film as zero point, and used the average value. Sheet resistance was measured about four test pieces using MILLIOHMMETER4338B (made by HEWLETT PACKARD), and used the average value. In addition, the range which can be detected by this milli-ohm meter is 1 * 10 <^-2> (ohm * cm), and the specific resistance of 1 * 10 <^-2> (ohm * cm) or more falls outside a measurement limit.

10. Pencil Hardness

The conductive laminate test piece 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.

11. Moisture and heat resistance test

The conductive laminate test piece was heated at 80 ° C for 300 hours, then heated at 85 ° C and 85% RH (relative humidity) for 300 hours, and then left at room temperature for 24 hours, and then various evaluations were performed.

12. Evaluation of laser etching processing aptitude

By the screen printing method, the electrically conductive paste was printed and apply | coated in the rectangle of 2.5x10 cm on the polyester base material (Lumiera S (100 micrometers thickness) by Toray Corporation). It printed by 150 mm / s of squeegee speeds using T400 stainless steel mesh (oil thickness of 10 micrometers, line diameter of 23 micrometers (made by Tokyo Process Service)) as a screen board. After printing application | coating, drying was performed for 30 minutes at 120 degreeC in the hot air circulation type drying furnace, and the electroconductive thin film was obtained. In addition, the paste was diluted and adjusted so that a film thickness might be 5-12 micrometers. Subsequently, laser etching was performed on the conductive thin film produced by the above method, a pattern having four straight portions having a length of 50 mm shown in FIG. 1 was produced, and a laser etching processing aptitude evaluation test piece was prepared. The laser etching process between the lines of the said linear part was performed by scanning the laser beam of 30 micrometers of beam diameters twice each at 60 micrometer pitch. A fiber laser was used for 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.

Evaluation items and measurement conditions are as follows.

(Laser etching processing width evaluation)

In the said laser etching processability evaluation test piece, the line width of the site | part from which the conductive thin film was removed was measured. The measurement was performed using the laser microscope (Keyence VHX-1000), and it determined on the following evaluation judgment criteria.

○; The line width of the site where the conductive thin film is removed is 28 to 32 μm

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

×; The line width of the portion where the conductive thin film is removed is 23 μm or less, or 37 μm or more

(Conductivity between both ends of laser etching processing aptitude evaluation (1))

The said laser etching processability evaluation test piece WHEREIN: It evaluated by the conduction between the both ends of the thin wire | line 1b, 2b, 3b, 4b being ensured. Specifically, the presence or absence of conduction is confirmed by applying a tester for each of terminals 1a to 1c, between terminals 2a to 2c, between terminals 3a to 3c and between terminals 4a to 4c. Judging.

○; There is conduction between both ends of all four thin wires

?; No conduction between the two ends of one of the four thin wires

×; No conduction between both ends of all four thin wires

(Laser etching processability evaluation (2) insulation between adjacent fine wires)

In the said laser etching processability evaluation test piece, it evaluated by whether the insulation between adjacent thin wires is ensured. Specifically, the presence or absence of conduction was confirmed by applying a tester to each of the terminals 1a-terminal 2a, the terminals 2a-terminal 3a, and the terminals 3a-terminal 4a, and determined the following evaluation criteria.

○; Insulation between all adjacent thin wires

?; Some adjacent fine wires are insulated

×; Not isolated between all adjacent thin wires

(Evaluation of residues at the sites where the conductive thin film was removed)

In the said laser etching processability evaluation test piece, the site | part from which the conductive thin film was removed was observed with the laser microscope, and the presence or absence of residue adhered was determined by the following evaluation criteria.

(Circle): There is no residue in the site | part from which the conductive thin film was removed.

(Triangle | delta): There exists some residue in the site | part from which the conductive thin film was removed.

X: A lot of residue is seen in the site | part from which the conductive thin film was removed.

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

Tape using cello tape (registered trademark) (manufactured by Nichiban Co., Ltd.) for adhesion to a substrate of a portion where the conductive thin film sandwiched between the conductive thin film from the laser etching processing aptitude evaluation test piece remains. It evaluated by the peel test. Immediately after 24 hours of the test piece preparation (initial stage), and after that, after standing still in a humid heat environment of 85 degreeC and 85% RH (relative humidity) for 120 hours, and further still standing at room temperature for 24 hours (after a moisture proof test) Done to.

(Circle): There is no peeling. (Triangle | delta): It peels in part. X: All peeled.

Production Example of Resin

Production Example of Polyester Resin P-1

Into a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 700 parts of terephthalic acid, 700 parts of isophthalic acid, 16.9 parts of trimellitic anhydride, 983 parts of ethylene glycol, and 154 parts of 2-methyl-1,3-propanediol were charged. Under 2 atmospheres of pressurization, the temperature was raised from 160 ° C to 230 ° C over 3 hours, and the esterification reaction was performed. 0.92 parts of tetrabutyl titanate was injected | poured after pressure_release, the pressure inside the system was gradually depressurized, it decompressed to 5 mmHg over 20 minutes, and the polycondensation reaction was performed at 260 degreeC for 40 minutes under the vacuum of 0.3 mmHg or less. . Then, it cooled to 220 degreeC under nitrogen stream, 50.6 parts of trimellitic anhydrides were thrown in, and it reacted for 30 minutes, and obtained polyester resin. Table 1 shows the composition and physical properties of the obtained copolymerized polyester resin P-1.

Manufacturing example of polyester resin P-2-P-11

In the manufacture example of polyester resin P-1, the kind and compounding ratio of a monomer were changed and polyester resin P-2-P-11 were manufactured. The composition and resin physical properties of the obtained copolyester resin are shown in Tables 1-2.

BPE-20F: Ethylene oxide adduct of bisphenol A (manufactured by Sanyo Kasei Co., 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 dimethylol butanoic acid (DMBA) were added to a reaction vessel equipped with a stirrer, a condenser and a thermometer, followed by ethyl diglycol acetate (EDGAC). ) 1087 parts were injected and dissolved at 85 ° C. Thereafter, 460 parts of 4,4'-diphenylmethane diisocyanate (MDI) was added, and the reaction was carried out at 85 ° C. for 2 hours, and then 0.5 part of dibutyl tin dilaurate was added as a catalyst. The reaction was time. Subsequently, the solution was diluted with 1940 parts of EDGAC, and the solution of polyurethane resin U-1 was obtained. Solid content concentration of the obtained polyurethane resin solution was 35 mass%. The resin solution obtained in this way was dripped on the polypropylene film, and it extended | stretched using the stainless steel applicator, and obtained the thin film of the resin solution. This was left to stand in a hot air dryer adjusted to 120 ° C for 3 hours to volatilize the solvent, and then the resin thin film was peeled off from the polypropylene film to obtain a film-shaped dry resin thin film. The thickness of the dry resin thin film was about 30 micrometers. Table 3 shows the evaluation results of various resin physical properties using the dried resin thin film as sample resin of polyurethane resin U-1.

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

Polyurethane resins U-2 to U-8 are the same methods as in Production Example of Polyurethane Resin U-1 except for replacing the polyester polyol, the compound having a group reacting with isocyanate, and the polyisocyanate as shown in Table 3. Manufactured. Table 3 shows the evaluation results of the resin physical properties of the polyurethane resins U-2 to U-8.

DMBA: Dimethylolbutanoic Acid

NPG: Neopentylglycol

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

MDI: 4,4'-diphenylmethane diisocyanate

IPDI: isophorone diisocyanate

Example 1

Kyoeisha Chemical Co., Ltd. make 2860 parts (1000 parts conversion) of the solution which melt | dissolved polyester resin P-1 in EDGAC so that solid content concentration might be 35 mass%, and flake type silver powder 1 as 7,888 parts, and a leveling agent. 30 parts of BK Chem Japan Japan Co., Ltd. make and 300 parts of EDGAC were mix | blended with 71 parts and MK beans as a dispersing agent, and it disperse | distributed by passing through three chilled roll kneaders three times. 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 physical properties were measured using this electroconductive thin film, and the laser etching process was then examined. Table 4 shows the evaluation results of the paste, the paste coating film, and the laser etching workability.

Examples 2 to 13

Examples 2 to 17 were implemented by changing the resin and the formulation of the conductive paste. The blending and evaluation results of the conductive paste are shown in Tables 4 to 6. In the Example, favorable coating film physical properties were obtained by the comparatively low temperature and short time heating of oven 120 degreeC * 30 minutes. Moreover, the adhesiveness to the ITO membrane and the adhesiveness after a wet heat environment test were also favorable.

In addition, in Tables 4-7, the binder resin, the conductive powder, the additive, and the solvent used the following.

Binder Resin PH-1: PKKH manufactured by InChem (Phenoxy resin, number average molecular weight 14000, Tg = 71 ° C)

Silver powder 1: Flake type silver powder (D50: 2 ㎛)

Silver powder 2: Spherical silver powder (D50: 1 μm)

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

Ketjen Black: Ketjen ECP600JD manufactured by Lion Co., Ltd.

Graphite Powder: Graphite BF manufactured by Chuets Graphite Industrial Co., Ltd.

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

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

Leveling agent: MK Conk, manufactured by Kyoeisha Chemical Co., Ltd.

Dispersant 1: Disperbyk130 manufactured by BIC Chemi Japan Co., Ltd.

Dispersant 2: Disperbyk2155 manufactured by BIC Chemi Japan Co., Ltd.

Dispersant 3: Disperbyk180 manufactured by Big Chemi Japan Co., Ltd.

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

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

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

EDGAC: Ethyl diglycol acetate of Daicel Co., Ltd.

BMGAC: Butyl glycol acetate of Daicel Co., Ltd.

BDGAC: Butyl diglycol acetate produced by Daicel Co., Ltd.

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

Comparative Example 1

Silver laurylcarboxylic acid (1000 g) and butylamine (480 g) were dissolved in toluene (10 L). Formic acid (150 g) was then added dropwise and stirred at room temperature for 1.5 hours as it was. This was decanted because the addition of large amounts of methanol precipitates aggregates of silver nanoparticles. After repeating the decantation three times, the precipitate was dried under reduced pressure. Subsequently, the obtained precipitate 1000g (of which 920g silver and carboxylic acid silver amine complex 80g) was redispersed in 1860g of tapineol, and the electrically conductive paste containing silver nanoparticles (silver powder 3) was obtained. Silver powder 3 obtained had a particle diameter of about 10 nm from a transmission electron micrograph. Solid content concentration of the electrically conductive paste was 35 mass%. Using the obtained electrically conductive paste, the electroconductive laminate test piece and the laser etching processability evaluation test piece were created like Example, and it evaluated similarly to the Example. The evaluation results are shown in Table 7. This electroconductive silver paste composition was inferior to initial stage coating film physical property especially, adhesiveness was lacking, and it was the thing which cannot endure practically.

Comparative Example 2

Dodecylamine was dissolved in tapineol to obtain a solution having a solid content concentration of 12% by weight. Glass frit ((bismuth oxide (Bi ₂ O ₃ )) pulverized with silver powder 4 (spherical silver powder (D50 = 1 μm) in a bead mill so as to have 8083 parts of an average particle diameter of 1.5 μm) in 1000 parts of this solution (120 parts by weight of solid). 250 parts of glass powder (bismuth oxide content 80.0 to 99.9%) containing as a main component was added, mixing continued, and after uniformizing, this solution was disperse | distributed with three roll mills and the glass frit containing conductive paste was produced. Using the paste, a conductive laminate test piece and a laser etching processability evaluation test piece were prepared in the same manner as in Example, and the evaluation was performed in the same manner as in Example 7. The evaluation results are shown in Table 7. The present conductive silver paste composition was initially applied. The film properties were remarkably inferior, in particular, the adhesiveness was insufficient, and practically unacceptable, and the laser etching processability was remarkably inferior and wider than the irradiation site. The coating film of the width | variety wider than the width | variety of the laser beam irradiated in the silver range peeled, and the predetermined | prescribed line | wire width was not able to be processed.

Industrial availability

The electrically conductive paste for laser etching processing of this invention can provide the electrically conductive thin film which is excellent in wet heat environment reliability, and can maintain the coating film durability as a conductive thin film, maintaining a laser etching processability, For example, a mobile telephone, a notebook, It is useful as a conductive paste used for 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 wires 1b, 2b, 3b, 4b
1c, 2c, 3c, 4c: Terminals 1c, 2c, 3c, 4c
5: Pattern formed on laser etching processability evaluation test piece

Claims (12)

L / S formed by laser etching a conductive thin film formed of a conductive resin containing a binder resin (A) containing a thermoplastic resin, a metal powder (B), and an organic solvent (C), where L and S are planar directions The width of the line and the space of respectively) is 50/50 μm or less circuit wiring, the binder resin (A) has a number average molecular weight of 5,000 to 60,000, and a glass transition temperature of 60 to 100 ℃ Resin, The said metal powder (B) has a center diameter (D50) of 4 micrometers or less, The said organic solvent (C) has a boiling point of 100 degreeC or more and less than 300 degreeC, The circuit wiring. delete The said binder resin (A) is 1 type, or 2 or more types of mixtures chosen from the group which consists of a polyester resin, a polyurethane resin, an epoxy resin, a phenoxy resin, a vinyl chloride resin, and a cellulose derivative resin. Circuit wiring, characterized in that. The method of claim 1, 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 of one or selected from the group consisting of urethane resin Circuit wiring characterized by the mixture of 2 or more types. The circuit wiring according to any one of claims 1, 3, and 4, further comprising a laser light absorbing agent (D). delete The electrically conductive laminated body formed by the circuit wiring of Claim 1 formed on a base material. 8. The conductive laminate according to claim 7, wherein the base material has a transparent conductive layer. An electrical circuit comprising the conductive laminate according to claim 7 or 8. The electric circuit which has a circuit wiring site | part of Claim 1 formed by irradiating the laser beam selected from a carbon dioxide gas laser, a YAG laser, a fiber laser, and a semiconductor laser to a part of conductive film, and removing a part of said conductive thin film. delete A touch panel comprising the electric circuit according to claim 9 as a constituent member.

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