KR102324621B1 - Conductive paste for laser etching, conductive thin film and conductive laminate - Google Patents

Abstract

The object of the present invention is that high-density electrode circuit wiring having an L/S of 50/50 µm or less, which is considered difficult to cope with by the conventional screen printing method, can be manufactured at low cost and with low environmental load, and furthermore, thermal deterioration of the substrate To provide a conductive paste for laser etching processing suitable for laser etching processing, which can reduce
The said subject is the electrically conductive paste for laser etching processing containing the binder resin (A) which consists of a thermoplastic resin, a metal powder (B), and an organic solvent (C). WHEREIN: The number average molecular weight of the said binder resin (A) is 5,000- It is solved by a conductive paste for laser etching processing, characterized in that it is a thermoplastic resin having a glass transition temperature of less than 60° C., a conductive thin film formed using the conductive paste, a conductive laminate, an electric circuit, and a touch panel.

Description

Conductive paste for laser etching processing, conductive thin film, and conductive laminate TECHNICAL FIELD

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

In recent years, performance enhancement and miniaturization of electronic devices equipped with transparent touch panels typified by mobile phones, notebook computers, electronic books, and the like are rapidly progressing. In addition to the miniaturization, performance improvement, and improvement of the degree of integration of mounted electronic components, high-density increase of the electrode circuit wiring for bonding these electronic components to each other is calculated|required for performance improvement and miniaturization of these electronic devices. As a transparent touch panel method, in addition to the resistive film method with a small number of electrode circuit wirings, the spread of the electrostatic capacitance method with a dramatically large number of electrode circuit wirings is rapidly progressing in recent years. have. Moreover, in order to enlarge a display screen, and also by a request|requirement on product design, there is a request|requirement to make narrower the frame part in which electrode circuit wiring is arrange|positioned, and high density of electrode circuit wiring is calculated|required also from this viewpoint. In order to satisfy the above request|requirement, the technique which can perform high-density arrangement|positioning of the electrode circuit wiring more than the conventional is calculated|required.

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

A photolithography method is mentioned as an example of a candidate of the electrode circuit wiring formation technique which will replace screen printing. If the photolithography method is used, it is also fully possible to form the thin wire whose L/S is 50/50 micrometers or less. However, the photolithography method also has a problem. The most typical example of the photolithography method is a method using a photosensitive resist. Generally, the 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 with a photomask or laser light. A thin wire pattern of copper foil is formed by exposing to exposure, developing a photosensitive resist, and dissolving and removing copper foil parts other than a desired pattern with a chemical|medical agent after that. For this reason, the environmental load by waste liquid treatment is large, and by extension, a process is complicated, and it has many subjects including a viewpoint of production efficiency and a viewpoint of cost.

In the photolithography method, there is also a method in which a photosensitive resist is not used. For example, in Patent Documents 1 and 2, a dry coating film is formed using an electrically conductive paste, and the photolithography method is directly drawn with a laser beam. A technique for forming a desired pattern by fixing the irradiated portion to a substrate and developing and removing the unirradiated portion is disclosed. In this method, compared to the general photolithography method, the process is simplified as much as the photosensitive resist is not used. However, as in the conventionally known photolithography method using a photosensitive resist, a wet process development step is required. In addition, since glass frit or nano-sized silver powder is used as a component of the conductive paste, a high temperature of 400° C. or higher is required in the firing process, which requires a lot of energy, but the available substrate is 400° C. There is a problem in that it is limited to withstand the firing process at the above high temperature. Furthermore, it cannot but be said that the process is complicated and it is inappropriate also in terms of production efficiency.

Under the circumstances described above, as an example of a candidate for the electrode circuit wiring formation technology to replace the screen printing, the laser etching method disclosed in Patent Document 3 is attracting attention in recent years. If the laser etching method is used, it is sufficiently possible to form a thin wire having an L/S of 50/50 µm or less. The laser etching method refers to a method in which a layer (hereinafter referred to as a conductive thin film) containing a binder resin and conductive powder is formed on an insulating substrate, and a part thereof is removed on the insulating substrate by laser light irradiation.

However, the laser etching method also has a problem. Since a large amount of heat is generated in the removal of the conductive thin film by laser beam irradiation, thermal deterioration is given to the conductive thin film and the substrate, and as a result, there is a fear that the adhesiveness and electrical properties necessary for the conductive thin film may be impaired. As a method of suppressing thermal deterioration, it is considered to make the energy of the laser smaller, but if the energy is too small, etching cannot be performed, short circuits and burrs are formed between the thin wires, which is also unsuitable for production efficiency.

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

An object of the present invention is to provide a manufacturing method capable of realizing high-density electrode circuit wiring even under low-energy laser conditions in order to minimize thermal deterioration of a substrate and conductive thin film by laser etching. Moreover, it is providing the electrically conductive paste which can be used suitably for such a manufacturing method.

The present inventors have intensively studied a manufacturing method for arranging electrode circuit wiring at high density in a planar direction, and as a result, have found a conductive paste suitable for forming a layer containing a binder resin and conductive powder suitable for a low-energy laser etching method. did. That is, this invention consists of the following structures.

1. A conductive paste for laser etching processing containing a binder resin (A) made of a thermoplastic resin, a metal powder (B) and an organic solvent (C), wherein the binder resin (A) has a number average molecular weight of 5,000 to 60,000 Furthermore, it is a thermoplastic resin whose glass transition temperature is less than 60 degreeC, The electrically conductive paste for laser etching processing characterized by the above-mentioned.

2. The binder resin (A) is one or a mixture of two or more selected from the group consisting of a polyester resin, a polyurethane resin, an epoxy resin, a phenoxy resin, a vinyl chloride resin, and a cellulose derivative resin. Conductive paste for laser etching processing as described in 1..

3. The binder resin (A) is 1 or 2. The laser etching processing of a conductive paste according to, characterized in that the acid value is less than 50 eq / 10 ⁶ g.

4. 1. to 3 characterized in that the conductive paste was filtered. The conductive paste for a laser etching process in any one of them.

5. Above 1.~4. The conductive thin film formed from the electrically conductive paste for laser etching processes in any one of them.

6. The conductive laminate in which the conductive thin film and the base material of 5. above are laminated|stacked.

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

8. An electric circuit formed by using the conductive thin film according to 5. or the conductive laminate according to 6. or 7.

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

10. The said conductive thin film is formed on the transparent conductive layer, The electric circuit as described in 9. characterized by the above-mentioned.

11. Above 8.~10. A touch panel comprising the electric circuit according to any one of the above as a constituent member.

The electrically conductive paste of this invention is an electrically conductive paste containing binder resin (A) which consists of a thermoplastic resin, a metal powder (B), and an organic solvent (C). WHEREIN: The said binder resin (A) has a number average molecular weight of 5,000- It is an electrically conductive paste characterized by being a thermoplastic resin whose glass transition temperature is less than 60 degreeC, and it is 60,000, and by taking such a structure, the electrically conductive thin film excellent in the laser etching processability in low energy can be formed. On the other hand, excellent laser etching processing ability means that when at least a part of the conductive thin film is peeled from the base material by laser etching to form a thin wire of L/S = 20/20 µm, 1) Conduction between both ends of the thin wire This is ensured, 2) the insulation between adjacent thin wires is ensured, 3) the thin wire shape is good, and 4) the substrate adhesiveness after laser etching is satisfactory. Further, by filtering the conductive paste, which is an embodiment of the present invention, a shear can be applied to the agglomerated silver powder to unravel, and coarse particles can be removed, thereby exhibiting the effect of improving etching defects.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the pattern which irradiates a laser beam to the laser etching processing aptitude evaluation test piece used by the Example of this invention, and the comparative example. A laser beam is irradiated to a white part, and the conductive thin film formed on the base material is removed. The laser beam is not irradiated to the halftone dots. The unit of the dimension display in the drawing is mm.

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

The conductive paste for laser etching in the present invention is a conductive paste for laser etching processing containing a binder resin (A) made of a thermoplastic resin, a metal powder (B), and an organic solvent (C), wherein the binder resin (A) is , a number average molecular weight of 5,000 to 60,000, and a glass transition temperature of a thermoplastic resin of less than 60°C, is contained as an essential component.

<Binder resin (A)>

The type 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-based resin, polycarbonate-based resin, phenolic resin, alkyd resin, styrene-acrylic resin, styrene-butadiene copolymer resin, polysulfone resin, polyethersulfone resin , vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, polystyrene, silicone resin, fluorine-based resin, etc. These resins can be used alone or as a mixture of two or more thereof. It is preferable that it is 1 type or a mixture of 2 or more types selected 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. In addition, among these resins, it is a binder resin ( As A), it is more preferable.

As one of the advantages of using a polyester resin as the binder resin (A) in the present invention, there is a high degree of freedom in molecular design. By selecting the dicarboxylic acid and glycol components constituting the polyester resin, the copolymerization component can be freely changed, and it is easy to provide a functional group in the molecular chain or at the molecular terminal. For this reason, characteristics of resin, such as affinity with the glass transition temperature of the polyester resin obtained, and the other component mix|blended with a base material and an electrically conductive paste, can be adjusted suitably.

As an example of the dicarboxylic acid which can be used as a copolymerization component of the polyester resin used as binder resin (A) in this invention, Aromatic dicarboxylic acids, such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid Aliphatic dicarboxylic acids such as carboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and azelaic acid, dibasic acids having 12 to 28 carbon atoms, such as dimer acid, 1,4-cyclo Hexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride Alicyclic dicarboxylic acids, such as phthalic acid, dicarboxy hydrogenated bisphenol A, dicarboxy hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalenedicarboxylic acid, and tricyclodecanedicarboxylic acid, hydroxy Hydroxycarboxylic acids, such as benzoic acid and lactic acid, are mentioned. In addition, within the scope not impairing the effects of the invention, trivalent or higher carboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid and/or 5-sulfoisophthalate sodium salt, etc. You may use together the sulfonic acid metal base containing dicarboxylic acid as a copolymerization component.

As an example of the polyol which can be used as a copolymerization component of the polyester resin used as binder resin (A) in this invention, ethylene glycol, propylene glycol, 1, 3- propanediol, 1, 4- butanediol, 1, 5-pentane Diol, neopentyl glycol, 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, and 1,10-decanediol; 1,4-cyclohexanediol and alicyclic diols such as methanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol and dimerdiol. Moreover, you may use together as a copolymerization component trivalence or more polyols, such as trimethylolethane, a trimethylol propane, glycerol, pentaerythritol, and polyglycerol, in the range which does not impair the effect of invention.

The polyester resin used as the binder resin (A) in the present invention contains an aliphatic dicarboxylic acid among all the acid components constituting the polyester resin from the viewpoints of adhesiveness, compatibility with other resins used in combination, and thermal shock resistance. It is preferable that 10 mol% or more is copolymerized, More preferably, it is 20 mol% or more, More preferably, it is 30 mol% or more. When the copolymerization ratio of an aromatic dicarboxylic acid component is too high, the glass transition temperature of the polyester resin obtained will be 60 degreeC or more, and deterioration of storage stability resulting from compatibility deterioration with the resin used together, and linearity of a laser etching process A fall and the adhesive fall after laser etching of the conductive thin film obtained may arise.

It is also a preferable embodiment to use a polyurethane resin as binder resin (A) in this invention. As in the case of the polyester resin, also for the polyurethane resin, by selecting an appropriate component as a copolymerization component constituting the polyurethane resin, and imparting a functional group in the molecular chain or at the molecular terminal, the glass transition temperature The properties of the resin, such as affinity with other components to be blended with the base material and the conductive paste, can be appropriately adjusted.

Although there is no limitation in particular also about the copolymerization component of a polyurethane resin, It is preferable that it is a polyester polyurethane resin using a polyester polyol as a copolymerization component from a viewpoint of the maintenance of freedom in design, heat-and-moisture resistance, and durability. As a preferable example of the said polyester polyol, the thing which 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. 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-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, m- Phenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 2,6-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4 '-diphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, m-xylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate etc. are mentioned, Any of aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate may be sufficient. Moreover, you may use together the isocyanate compound more than trivalence as a copolymerization component in the range which does not impair the effect of this invention.

In the polyurethane resin used as the binder resin (A) in the present invention, a compound having a functional group capable of reacting with isocyanate can be copolymerized as needed. As a functional group which can react with isocyanate, a hydroxyl group and an amino group are preferable, and it may have either one or 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, and 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'-hydroxypropanate, 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- Compounds having two hydroxyl groups in one molecule, such as dimethyl-3-sodium sulfo-2,5-hexanediol and dimerdiol (eg PRIPOOL-2033 manufactured by Unichema International), trimethylolethane, trimethylolpropane, glycerin , pentaerythritol, polyglycerin, etc. alcohols having three or more hydroxyl groups in one molecule, monoethanolamine, diethanolamine, triethanolamine, etc., amino alcohols having one or more hydroxyl groups and amino groups in one molecule, ethylenediamine, 1, aliphatic diamines such as 6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine; and compounds having two amino groups in one molecule, such as aromatic diamines such as 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether. have. 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 described above may be used alone or in combination, without any problem.

The epoxy resin used as the binder resin (A) in the present invention is, for example, a glycidyl ether type such as bisphenol A glycidyl ether, bisphenol S glycidyl ether, novolac glycidyl ether, bisbromide, hexa Glycidyl ester types such as hydrophthalic acid glycidyl ester and dimer acid glycidyl ester, triglycidyl isocyanurate, or 3,4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, epoxidized soybean oil Alicyclic or aliphatic epoxides, such as these, are mentioned, Even if used individually by 1 type, or 2 or more types may be used together, it is not cared about. Among these, from a viewpoint of durability of a coating film, bisphenol A glycidyl ether is preferable, and it is more preferable to have two or more glycidyl ether groups in 1 molecule.

Although limitation in particular is not carried out as for the number average molecular weight of binder resin (A) in this invention, It is preferable that number average molecular weights are 5,000-60,000, More preferably, it is 10000-40000. When the number average molecular weight is too low, it is unpreferable from the point of durability of the formed conductive thin film, and heat-and-moisture resistance. On the other hand, when the number average molecular weight is too high, the cohesive force of resin will increase and durability etc. as a conductive thin film will improve, but laser etching processability deteriorates remarkably.

It is preferable that it is less than 60 degreeC, and, as for the glass transition temperature of binder resin (A) in this invention, it is more preferable that it is 30 degrees C or less. More preferably, it is 15 degrees C or less. Setting it to a lower glass transition temperature has the effect of improving the surface smoothness of a silver coating film, and improving the sharpness of the thin wire|wire after laser etching. Moreover, since a silver coating film becomes more tacky, high base material adhesiveness can be implement|achieved as a result. On the other hand, although the lower limit of the glass transition temperature of binder resin (A) is not specifically limited, Usually, it is about -20 degreeC or more.

Although the acid value of the binder resin (A) in the present invention is not particularly limited, if the acid value is too high, the water absorption of the conductive thin film to be formed increases, and there is a possibility that hydrolysis of the binder resin may be accelerated by the catalytic action of the carboxyl group. , which may lead to a decrease in the reliability of the conductive thin film. The lower the glass transition temperature is more pronounced for hydrolysis, and the glass transition temperature of the present application is disadvantageous from the viewpoint of hydrolysis. Therefore, by setting the acid value of the binder resin (A) to a low acid value, preferably less than 50 eq/ton, more preferably 30 eq/ton or less, a conductive paste having high reliability of a conductive thin film and linearity and adhesiveness of laser etching came to realization.

<Metal powder (B)>

As metal powder (B) used in this invention, noble metal powders, such as silver powder, gold powder, platinum powder, palladium powder, non-metal powders, such as copper powder, nickel powder, aluminum powder, brass powder, Plating with noble metals, such as silver Or alloyed non-metal powder etc., for example, silver-coated copper powder is mentioned. These metal powders may be used independently and may be used together. Among these, when considering electroconductivity, stability, cost, etc., it is preferable to have silver powder alone or silver powder mainly.

The shape of the metal powder (B) used for this invention is not specifically limited. As an example of the shape of the metal powder known conventionally, flake shape (scale shape), spherical shape, branch shape (dendrite type), spherical primary described in Japanese Patent Laid-Open No. 9-306240 There is a shape in which the particles are aggregated in a three-dimensional form (agglomerated type), etc., among them, from the viewpoint of laser etching property, it is preferable to use a spherical, agglomerated and flake-shaped metal powder, and more preferably a flake-like or spherical shape. .

It is preferable that the center diameter (D50) of the metal powder (B) used for this invention is 4 micrometers or less. By using the metal powder (B) with a central diameter of 4 micrometers or less, there exists a tendency for the fine wire shape of a laser etching process site|part to become favorable. When a metal powder with a center diameter larger than 4 micrometers is used, the shape of the thin wire after a laser etching process worsens, as a result, the thin wire raise|generates contact and may cause a short circuit. Furthermore, by a laser etching process, the electrically conductive thin film which peeled and removed once may adhere to a process site|part again. The lower limit of the central diameter of the metal powder (B) is not particularly limited, but from the viewpoint of cost and when the particle diameter becomes fine, agglomeration tends to occur, and dispersion becomes difficult as a result. Therefore, the central diameter is preferably 80 nm or more. When the central diameter is smaller than 80 nm, the cohesive force of the metal powder increases and laser etching processing aptitude deteriorates, and it is also undesirable from the viewpoint of cost.

On the other hand, in the cumulative distribution curve (volume) obtained by a certain measuring method, the central diameter (D50) means the particle diameter (micrometer) at which the cumulative value becomes 50%. In the present invention, the cumulative distribution curve is measured in total reflection mode using a laser diffraction scattering type particle size distribution analyzer (manufactured by Nikiso 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 resins (A), and, as for content of a metal powder (B), 560 mass parts or more are more preferable. Moreover, from a viewpoint of being favorable in adhesiveness with a base material, 1,900 mass parts or less are preferable with respect to 100 mass parts of thermoplastic resins (A), and, as for content of (B) component, 1,230 mass parts or less is more preferable.

<Organic solvent (C)>

Although the organic solvent (C) which can be used for this invention is not specifically limited, From a viewpoint of maintaining the volatilization rate of an organic solvent in an appropriate range, it is preferable that a boiling point is 100 degreeC or more and less than 300 degreeC, More preferably, 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 the thermoplastic resin (A), the metal powder (B), the organic solvent (C) and, if necessary, other components with a three roll mill or the like, in which case the organic solvent is When a boiling point is too low, a solvent may volatilize during dispersion|distribution, and there exists a possibility that the component ratio which comprises an electrically conductive paste may change. On the other hand, when the boiling point of the organic solvent is too high, there is a possibility that a solvent may remain|survive in a coating film in large quantity depending on drying conditions, and there exists a possibility of causing the reliability fall of a coating film.

Moreover, as an organic solvent (C) which can be used for this invention, a thermoplastic resin (A) is soluble, and what can disperse|distribute a metal powder (B) favorably is preferable. Specific examples include ethyl diglycol acetate (EDGAC), butyl glycol acetate (BMGAC), butyl diglycol acetate (BDGAC), cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, Solve manufactured by Exxon Chemical. Solvesso 100, 150, 200, propylene glycol monomethyl ether acetate, adipic acid, a mixture of succinic acid and dimethyl ester of glutaric acid (for example, DBE manufactured by DuPont Co., Ltd.), terpineol, etc. can be mentioned. However, among them, EDGAC, BMGAC, BDGAC and these A mixed solvent of

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 with respect to 100 parts by weight of the total weight of the paste. When content of the organic solvent (C) is too high, there exists a tendency for a paste viscosity to become low too much, and to become 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, for example, screen printability at the time of forming a conductive thin film remarkably falls, and the film thickness of the formed conductive thin film becomes thick, and laser etching Processability may fall.

<Laser light absorber (D)>

You may mix|blend a laser beam absorber (D) with the electrically conductive paste of this invention. Here, the laser light absorber (D) refers to an additive having strong absorption in the wavelength of the laser light, and the laser light absorber (D) itself may be conductive or non-conductive. 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 absorber (D). By mix|blending a laser beam absorber (D), the conductive thin film of this invention absorbs a laser beam with high efficiency, volatilization and thermal decomposition of the binder resin (A) by heat_generation|fever are accelerated|stimulated, As a result, laser etching processability improves.

Among the laser light absorbers (D) that can be used in the present invention, examples of the conductive ones include carbon-based fillers such as carbon black and graphite powder. The carbon-based filler has an effect of increasing the conductivity of the conductive thin film of the present invention. For example, since carbon black has an absorption wavelength in the vicinity of 1060 nm, laser light having a wavelength of 1064 nm, such as a YAG laser or a fiber laser, can be used. When irradiated, since the conductive thin film absorbs laser light with high efficiency, the sensitivity to laser light irradiation increases, and the effect that good laser etching processing aptitude is obtained even when the scanning speed of laser irradiation is increased and/or when the laser light source is low power can be expected 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), 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 beam 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 decrease, and the resin adsorbs to the voids of the carbon, resulting in a problem in that the adhesion to the substrate decreases. .

Among the laser light absorbers (D) that can be used in the present invention, examples of non-conductive ones include conventionally known dyes, pigments, and infrared absorbers. More specifically, azo dyes, metal complex salts azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyryl As dyes and pigments such as lithium salts and metal thiolate complexes, black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, other polymer-bound pigments can be heard 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, It is possible to use isoindolinone pigments, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, and inorganic pigments. Examples of the infrared absorber include NIR-IM1, which is a dimonium salt type infrared absorber, and NIR-AM1, which is an aminium salt type, manufactured by Nagase Chemtex. These non-conductive laser-beam absorbers (D) are 0.01-5 weight part, It is preferable to contain 0.1-2 weight part preferably. When the compounding ratio of a nonelectroconductive laser beam absorber (D) is too low, the effect of raising the sensitivity with respect to laser beam irradiation is small. When the blending ratio of the non-conductive laser light absorber (D) is too high, there is a fear that the conductivity of the conductive thin film decreases, and the color tone of the laser light absorber becomes remarkable, which is not preferable depending on the 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 nitrides such as boron nitride, titanium nitride, and zirconium nitride, and various borides such as zirconium boride; Various oxides, such as titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica, fumed silica (For example, Nippon Aerosil Co., Ltd. AEROSIL), colloidal silica, etc. ; 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 fluorocarbon; various metal soaps such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate; In addition, talc, bentonite, talc, calcium carbonate, kaolin, glass fiber, mica, etc. can be used. By adding these inorganic substances, it may become possible to improve printability, heat resistance, and also mechanical properties and long-term durability. Especially, in the electrically conductive paste of this invention, a fumed silica is preferable from a viewpoint of providing durability, printability, especially screen printing ability.

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

<curing agent (E)>

You may mix|blend the binder resin (A) and the hardening|curing agent which can react with the electrically conductive paste of this invention to such an extent that the effect of this invention is not impaired. By blending the curing agent, there is a possibility that the curing temperature will increase and the load on the production process may increase.

Although the kind of hardening|curing agent which can react with the binder resin (A) of this invention is not limited, an isocyanate compound and/or an epoxy resin are especially preferable from adhesiveness, bending resistance, sclerosis|hardenability, etc. Moreover, about an isocyanate compound, when what made the isocyanate group block is used, storage stability improves and it is preferable. Examples of the curing agent other than the isocyanate compound include amino resins such as methylated melamine, butylated melamine, benzoguanamine and urea resin, and known compounds such as acid anhydrides, imidazoles and phenol resins. A well-known catalyst or accelerator selected according to the kind can also be used together with these hardening|curing agents. As a compounding quantity of a hardening|curing agent, it is mix|blended to the extent that the effect of this invention is not impaired, It is although it does not restrict|limit, 0.5-50 mass parts is preferable with respect to 100 mass parts of binder resin (A), 1-30 mass parts is more preferable. and 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 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, 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 excess amounts of these isocyanate compounds, for example, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, mono and a terminal isocyanate group-containing compound obtained by reacting with a low-molecular active hydrogen compound such as ethanolamine, diethanolamine, or triethanolamine, or a high-molecular active hydrogen compound such as various polyester polyols, polyether polyols, and polyamides. Moreover, as an isocyanate group blocking agent, For example, phenols, such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, 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 lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam and β-propiolactam, in addition to aromatic amines, imides, acetylacetone, acetoacetic acid ester, and malonic acid ethyl ester. Active methylene compounds, such as mercaptans, imines, imidazoles, urea, diaryl compounds, sodium bisulfite, etc. are mentioned. Among these, oximes, imidazoles, and amines are particularly preferable in terms of curability.

The epoxy compound used as the curing agent in the present invention is, for example, a glycidyl ether type such as bisphenol A glycidyl ether, bisphenol S glycidyl ether, novolac glycidyl ether, and bisbromide, glycidyl hexahydrophthalate. ester, glycidyl ester type such as dimer acid glycidyl ester, triglycidyl isocyanurate, or alicyclic such as 3,4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, and epoxidized soybean oil; An aliphatic epoxide etc. are mentioned, Even if used individually by 1 type, or 2 or more types may be used together, it is not cared about. Among these, from a viewpoint of sclerosis|hardenability, bisphenol A glycidyl ether is the most preferable, and among them, molecular weight less than 5000, and one which has two or more glycidyl ether groups in 1 molecule is still more preferable.

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

The viscosity of the electrically conductive paste of this invention is not specifically limited, What is necessary is just to adjust suitably according to the formation method of a coating film. For example, when applying the conductive paste to the substrate by screen printing, the viscosity of the conductive paste is preferably 100 dPa·s or more, more preferably 150 dPa·s or more at the printing temperature. Although an upper limit is not specifically limited, When a viscosity is too high, the film thickness of a conductive thin film may become thick too much, and laser etching processing aptitude may fall.

It is preferable that F-value of the electrically conductive paste of this invention 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 it is represented by F value = (filler mass part/solid content mass part) x100. A filler mass part here is a mass part of an electroconductive powder, and a solid content mass part is a mass part of components other than a solvent, and all of the electroconductive powder, binder resin, and other hardening|curing agent and additives are included. When the F value is too low, a conductive thin film exhibiting good conductivity cannot be obtained, and when 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 tends to decrease, and a decrease in printability is unavoidable. . In addition, electroconductive powder refers to both the electroconductive powder containing a metal powder (B) and a nonmetal here.

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

As described above, the conductive paste of the present invention can be prepared by dispersing the thermoplastic resin (A), the metal powder (B), the organic solvent (C) and, if necessary, other components in three rolls or the like. Here, an example of a more specific production procedure is shown. The thermoplastic resin (A) is first dissolved in the organic solvent (C). Then, the metal powder (B) and an additive are added as needed, and it disperse|distributes with a double planetary, a dissolver, a planetary stirrer, etc. Then, it disperse|distributes by 3 roll mill and obtains an electrically conductive paste. The electrically conductive paste obtained in this way can be filtered as needed. There is no problem even if it disperses using other dispersers, such as a bead mill, a kneader, an extruder, etc.

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

The conductive thin film of this invention can be formed by apply|coating or printing the electrically conductive 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 the coating film. The method of applying or printing the conductive paste on the substrate is not particularly limited, but printing by the screen printing method is preferable in terms of the simplicity of the process and the widespread technology in the industry for forming an electric circuit using the conductive paste. In addition, it is preferable that the conductive paste is applied or printed on a portion wider than the conductive thin film portion finally required as an electric circuit from the viewpoint of reducing the load on the laser etching process and efficiently forming the electric circuit of the present invention.

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, a film made of a material having excellent flexibility such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate or polycarbonate may be mentioned. Moreover, inorganic materials, such as glass, can also be used as a base material. The thickness of the substrate is not particularly limited, but is preferably 50 to 350 μm, and more preferably 100 to 250 μm in mechanical properties, shape stability, or handleability of the pattern forming material.

Moreover, the adhesiveness of a conductive thin film and a base material can be improved by performing a physical process and/or a chemical process to the surface of the base material which apply|coats the electrically conductive paste of this invention. Examples of the physical treatment method include a sand blasting method, a wet blasting method in which a liquid containing fine particles is sprayed, a corona discharge treatment method, a plasma treatment method, an ultraviolet or vacuum ultraviolet irradiation treatment method, and the like. Moreover, as an example of a chemical treatment method, the strong acid treatment method, the strong alkali treatment method, the oxidizing agent treatment method, the coupling agent treatment method, etc. are mentioned.

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

It is preferable to perform the process of volatilizing the organic solvent (C) under normal temperature and/or heating. When heating, from the viewpoint of improving the conductivity, adhesiveness, and surface hardness of the conductive thin film after drying, the heating temperature is preferably 80°C or higher, more preferably 100°C or higher, and still more preferably 110°C or higher. In addition, from the viewpoint of heat resistance of the transparent conductive layer of the underlying substrate and energy saving in the production process, the heating temperature is preferably 150°C or less, more preferably 135°C or less, and still more preferably 130°C or less. When a hardening|curing agent is mix|blended with the electrically conductive paste of this invention, when the process of volatilizing an organic solvent (C) is performed under heating, hardening reaction will advance.

What is necessary is just to set the thickness of the conductive thin film of this invention to suitable thickness according to the use used. However, from the viewpoint of good conductivity of the conductive thin film after drying and good laser etching processing aptitude, the thickness of the conductive thin film is preferably 3 µm or more and 30 µm or less, more preferably 4 µm or more, 20 It is micrometer or less, More preferably, they are 4 micrometers or more and 10 micrometers or less. When the film thickness of a conductive thin film is too thin, the desired electroconductivity as a circuit may not be acquired. When the film thickness is too thick, the amount of laser irradiation required for laser etching processing is excessively required, which may damage the substrate. Moreover, when the fluctuation|variation of a film thickness is large, a fluctuation|variation arises in the etching easiness of a conductive thin film, and there exists a tendency for the short circuit between lines by insufficient etching or disconnection by etching excess to arise easily. For this reason, it is preferable that the fluctuation|variation of a film thickness is small.

As for surface roughness Ra of the conductive thin film of this invention, 0.7 micrometer or less is preferable, More preferably, it is 0.5 micrometer or less. When surface roughness Ra is too high, it will become easy to generate jaggedness in the etching edge part of a conductive thin film, and the short circuit between lines and the disconnection by etching excess may become easy to generate|occur|produce. Since the surface roughness Ra is strongly influenced by the paste composition (particularly the binder species and the silver powder species), the paste viscosity, and the screen printing conditions, it is necessary to control them by appropriately adjusting them.

<<Electric circuit of the present invention and its manufacturing method>>

The electric circuit of this invention is an electric circuit which has a wiring site|part formed by irradiating a laser beam to at least a part of a conductive thin film formed on a base material with the electrically conductive paste of this invention, and removing a part of said conductive thin film on a base material. By adopting this method of forming an electric circuit, unlike the photolithography method, the pattern forming process can be made as a dry process, and since waste liquid containing metal components is not generated, there is no need for waste liquid treatment, etc., making it an environmentally friendly process. can In addition, since the process is simple, investment in manufacturing equipment can be suppressed, and maintenance after operation of the manufacturing equipment is easy. In addition, the method of forming a conductive thin film on a base material with an electrically conductive paste is although it does not specifically limit, It can carry out by printing or painting.

Although the irradiation method of a laser beam is not specifically limited, The thing which further improved the dimensional accuracy of the laser etching processing apparatus which propagation is advancing in recent years can be used. In a laser etching processing apparatus, since data produced by image processing application software such as CAD can be used for laser processing as it is, it is very easy to change a manufacturing pattern. This is mentioned as one of the advantages with respect to the pattern formation by the screen printing method which has been conventionally performed.

In the site|part where the laser beam was irradiated and absorbed, the energy of a laser beam is converted into heat|fever, thermal decomposition and/or volatilization arises by a temperature rise, and the irradiation site|part is peeled and removed. In order that the site|part to which the laser beam of the conductive thin film of this invention was irradiated is efficiently removed 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 the laser species, it is preferable to select a laser species having energy in a wavelength region in which any one component constituting the conductive thin film of the present invention has strong absorption.

Common laser types include excimer laser (fundamental wave wavelength 193 to 308 nm), YAG laser (fundamental wave wavelength 1064 nm), fiber laser (fundamental wave wavelength 1060 nm), and CO ₂ laser (fundamental wave wavelength of 1060 nm). The wavelength is 10600 nm), semiconductor laser, etc. are mentioned. Basically, there is no problem in using any type of laser type and any wavelength. By selecting a laser species that matches the absorption wavelength region of any one component of the conductive thin film and can irradiate a wavelength that the substrate does not have strong absorption, the conductive thin film at the laser beam irradiation site is efficiently removed, Moreover, damage to the substrate can be avoided. From such a viewpoint, the wavelength of the fundamental wave is preferably in the range of 532 to 10700 nm as the laser species to be irradiated. When using a conductive thin film having polyester in a layered structure as a substrate, or a thin film in which a part of a conductive thin film having polyester in a layered structure is removed by etching, using a YAG laser or a fiber laser is the wavelength of the fundamental wave. Since the substrate does not have water absorption, it is particularly preferable in that it is difficult to damage the substrate.

The laser output and frequency are not particularly limited, but the conductive thin film at the laser beam irradiation site can be removed with an etching width of 10 to 50 μm, and is controlled so as not to damage the underlying substrate. Generally, it is preferable to adjust a laser output suitably in 0.5-100 W, a frequency of 10-1000 kHz, and the range of 1000 ns or less of pulse width. When the laser output is too low, the removal of the conductive thin film tends to be insufficient, but such a tendency can be avoided to some extent by lowering the scanning speed of the laser or increasing the number of scanning. When laser output is too high, the site|part from which a conductive thin film peels by the diffusion of heat|fever from an irradiated part becomes extremely large than a laser beam diameter, and a line|wire width may become too thin or disconnection. In this regard, the laser output is preferably adjusted appropriately in a range of 0.5 to 20 W, a frequency of 10 to 800 kHz, and a pulse width of 800 ns or less, more preferably 0.5 to 12 W, a frequency of 10 to 600 kHz, a pulse The width is 600 ㎱ or less.

As for the scanning speed of a laser beam, from a viewpoint of the productivity improvement by reduction of a tact time, it is so good that it is high, specifically, 1000 mm/s or more is preferable, 1500 mm/s or more is more preferable, More preferably, 2000 mm/s or more is more preferable. mm/s or more. When the scanning speed is too slow, not only the production efficiency will fall, but there exists a possibility that a conductive thin film and a base material may be damaged by a thermal history. Although the upper limit in particular of a processing speed is not set, 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 be short-circuited. In addition, if the scanning speed is too fast, in the corner portion of the pattern to be formed, since it is inevitable to reduce the scanning speed compared to the linear portion, the thermal history of the corner portion becomes higher than that of the linear portion, There exists a possibility that the physical property of the conductive thin film around an etching process site|part may fall remarkably.

The laser beam scanning may be performed by moving a laser beam projectile, moving a laser beam irradiated object, or a combination of both, and can be realized by, for example, using an XY stage. Moreover, a laser beam can also be scanned by changing the irradiation direction of a laser beam using a galvanometer mirror etc.

When irradiating a laser beam, the energy density per unit area can be raised by using a condensing lens (achromatic lens etc.). An advantage of this method is that the energy density per unit area can be increased as compared with the case of using a mask, so that it becomes possible to perform laser etching processing at a high scanning speed even with a laser oscillator having a small output. When irradiating the condensed laser beam to a conductive thin film, it is necessary to adjust a focal length. Although it is necessary to adjust the focal length especially according to the film thickness applied to the base material, it is preferable to adjust so that it can peel/remove a predetermined conductive thin film pattern without damaging a base material.

It is one of preferable embodiment to repeatedly perform scanning of a laser beam in the same pattern multiple times. Even when there is an incompletely removed conductive thin film site in the first scan, or even when the component constituting the removed conductive thin film adheres to the substrate again, it is possible to completely remove the conductive thin film at the laser beam irradiation site by multiple scans. . Although the upper limit of the number of injections is not particularly limited, care is required because there is a possibility that the area around the processing site is damaged, discolored, and the physical properties of the coating film may be deteriorated when the area around the processing site is subjected to a plurality of heat history. In addition, from the point of production efficiency, it goes without saying that the fewer the number of scans, the better.

It is also one of preferable embodiment not to repeatedly perform scanning of a laser beam in the same pattern multiple times. As long as the properties of the resulting conductive thin film, conductive laminate, and electric circuit are not adversely affected, it goes without saying that the fewer the number of scans, the better the production efficiency.

Since the conductive thin film of the present invention contains expensive conductive powder in a high concentration, considering the total cost required for the production of an electric circuit, it is better to recover and reuse the conductive powder contained in the conductive thin film removed from the substrate. It is important. By installing a high-performance dust collector in the vicinity of the laser beam irradiation site and constructing a system for efficiently recovering the conductive powder, a sufficiently profitable processing method can be obtained.

<<Touch panel of the present invention>>

The conductive thin film, the conductive laminate, and/or the electric circuit of the present invention can be used as a constituent member of a touch panel. The touch panel may be a resistive film type or a capacitive type. Although application is possible to any touch panel, since this paste is suitable for thin wire formation, it can use especially suitably for the electrode wiring of a capacitive touch panel. On the other hand, as the base material constituting the touch panel, it is preferable to use a base material having a transparent conductive layer such as an ITO film or a silver nanowire film, or a base material from which these are partially removed by etching.

Example

In order to demonstrate this invention in more detail, although an Example and a comparative example are given below, this invention is not limited in any way by an Example. In addition, each measured value described in an Example and a 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 through a polytetrafluoroethylene membrane filter having a pore diameter of 0.5 µm to obtain a GPC measurement sample. Using tetrahydrofuran as a mobile phase, using a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation, a differential refractometer (RI system) as a detector, a column temperature of 30° C., and a flow rate of 1 ml/min. of GPC was measured. In addition, the number average molecular weight made it standard polystyrene conversion value, abbreviate|omitted the part corresponded to molecular weight less than 1000, and computed it. As the GPC column, shodex KF-802, 804L, and 806L manufactured by Showa Denko Co., Ltd. were used.

2. Glass transition temperature (Tg)

5 mg of the sample resin was put into an aluminum sample pan, sealed, and measured using a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Co., Ltd. at a temperature increase rate of 20°C/min to 200°C, and glass It was calculated as the temperature of the intersection of the extension line of the baseline below the transition temperature and the tangent line representing the maximum inclination at the transition.

3. Acid number

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

4. Resin composition

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

5. Paste Viscosity

In the sample temperature of 25 degreeC, the measurement of a viscosity measured in 20 rpm using the BH-type viscometer (made by Toki Sangyo).

6. Storage stability of conductive paste

The conductive paste was put in a poly container, and the stopper was stored at 40°C for 1 month. After storage, viscosity measurement and evaluation of the test pieces produced by the following 7. Conductive laminate test pieces were performed.

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

x: Any of a remarkable viscosity increase (2 times or more of initial viscosity) or a remarkable viscosity fall (1/2 or less of an initial viscosity) and/or a specific resistance, pencil hardness, and/or a fall of adhesiveness is seen.

7. Preparation of Conductive Laminate Test Pieces

For each of the PET film (Lumira S manufactured by Toray Corporation) and the ITO film (KH300 manufactured by Oike Kogyo Co., Ltd.) subjected to annealing treatment with a thickness of 100 μm, a 400 mesh stainless steel screen was used to conduct conductivity by screen printing. The paste was printed to form a seamlessly painted pattern having a width of 25 mm and a length of 450 mm, which was then heated in a hot air circulation drying furnace at 130° C. for 30 minutes to obtain a conductive laminate test piece. On the other hand, the coating thickness at the time of printing was adjusted so that a dry film thickness might be set to 4-10 micrometers.

8. Adhesion

The electroconductive laminate test piece was evaluated in accordance with JIS K-5400-5-6:1990 by peeling test using Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd.). However, the number of cuts in each direction of the grid pattern was 11, and the cut interval was 1 mm. 100/100 shows that adhesiveness is favorable without peeling, and 0/100 shows that all has peeled.

9. Resistivity

The sheet resistance and the 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 Ono Soki Co., Ltd.) as the film thickness, and the thickness of the cured coating film was measured at the zero point, and the average value was used. Sheet resistance was measured for 4 test pieces using MILLIOHMMETER4338B (manufactured by HEWLETT PACKARD), and the average value was used. On the other hand, the range that can be detected by this milliohmmeter is 1×10 ^-2 or less (Ω·cm), and a ^{specific resistance 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 plate having a thickness of 2 mm, and pencil hardness was measured according to JIS K 5600-5-4:1999.

11. Moist 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 to stand at room temperature for 24 hours, followed by various evaluations.

12. Surface finish

The said electroconductive laminated body test piece WHEREIN: The surface roughness Ra was measured using the surface roughness meter (Handy Surf E-35B, the Tokyo Seimitsu company make, calculated based on JIS-1994).

13. Evaluation of laser etching processing aptitude

By the screen printing method, on the polyester base material (Lumira S (thickness 100 micrometers) by Toray Corporation), the electrically conductive paste was printed and apply|coated in a 2.5x10 cm rectangle. A 400 stainless steel mesh (oil agent thickness of 10 µm, wire diameter of 18 µm (manufactured by Murakami Corporation, calendering)) was used as a screen plate, and printing was performed at a squeegee speed of 50 mm/s. After printing and application|coating, drying for 30 minutes was performed at 130 degreeC in the hot-air circulation type drying furnace, and the conductive thin film was obtained. In addition, the paste was diluted and adjusted so that the film thickness might be set to 5-7 micrometers. Then, the conductive thin film created by the above method was subjected to laser etching processing to produce a pattern having four linear portions having a length of 50 mm as shown in Fig. 1 , and used as a laser etching processing aptitude evaluation test piece.

The laser etching processing between the lines was performed by scanning a laser beam three times at a pitch of 40 µm (L/S=20/20 µm). A YAG laser (wavelength: 1064 nm) is used as the laser light source, with a frequency of 220 kHz, an output of 8 W, a scanning speed of 2800 mm/s, a pulse width of 75 ns (Condition 1), a frequency of 500 kHz, an output of 8 W, and a scanning speed. It performed in both of 2800 mm/s and 15 ns of pulse widths (condition 2). As a result of calculating the pulse energy by the following formula, the condition 1 was 36 µJ and the condition 2 was 16 µJ.

Pulse Energy = Output/Frequency

From this, it can be said that condition 2 is a low-energy etching rather than condition 1.

Evaluation items and measurement conditions are as follows.

(Laser etching processing width evaluation)

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

○; The line width of the area where the conductive thin film is removed is 18-22 ㎛

△; The line width of the area where the conductive thin film is removed is 14~17 ㎛ or 23~26 ㎛

×; The line width of the portion where the conductive thin film is removed is 13 μm or less, or 27 μm or more

(Laser etching processing aptitude evaluation 1 Conductivity between both ends of the thin wire)

The said laser etching processing aptitude evaluation test piece WHEREIN: It evaluated by whether conduction|electrical_connection between the both ends of a thin wire was ensured. Specifically, by applying a tester to each of the terminals A1-terminal B1, terminal A2-terminal B2, terminal A3-terminal B3, and terminal A4-terminal B4, the presence or absence of conduction is checked, and judgment is made according to the following evaluation criteria did.

○; For all four thin wires, there is conduction between both ends of the thin wires.

△; There is no conduction between both ends of the thin wire for 1 to 3 of the 4 thin wires

×; There is no conduction between both ends of the thin wire for all four thin wires

(Laser etching processing aptitude evaluation 2 Insulation between adjacent fine wires)

The said laser etching processing aptitude evaluation test piece WHEREIN: It evaluated by whether the insulation between adjacent thin wires was ensured. Specifically, the tester was applied to each of the terminals A1-terminal A2, the terminal A2-terminal A3, and the terminal A3-terminal A4, the presence or absence of conduction was confirmed, and it judged by the following evaluation criteria.

○; All adjacent fine wires are insulated

△; Some adjacent fine wires are insulated

×; All adjacent fine wires are not insulated

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

The said laser etching processing aptitude evaluation test piece WHEREIN: The site|part from which the conductive thin film was removed was observed with the laser microscope, and the following evaluation criteria determined the presence or absence of adhesion of a residue.

(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: Many residues are seen in the site|part from which the conductive thin film was removed.

(Evaluation of the adhesion between the conductive thin film and the base material after laser etching)

A tape using CelloTape (registered trademark) (manufactured by Nichiban Co., Ltd.) for the adhesion to the substrate of the portion where the conductive thin film sandwiched between the portion from which the conductive thin film has been removed in the laser etching processing aptitude evaluation test piece. It was evaluated by peeling test. This evaluation is performed immediately after 24 hours of test piece preparation (initial) and after that, after standing still for 120 hours in a moist heat environment of 85° C. and 85% RH (relative humidity) and standing still at room temperature for 24 hours (within the after wet heat test).

(circle): There is no peeling. (triangle|delta): A part peels. x: All peel.

Preparation example of resin

Preparation example of polyester resin P-1

700 parts of terephthalic acid, 420 parts of isophthalic acid, 246 parts of adipic acid, 680 parts of ethylene glycol, and 614 parts of neopentyl glycol were placed in a reaction vessel equipped with a stirrer, a condenser and a thermometer, and under a nitrogen atmosphere under 2 atmospheres of pressure, 160°C to 230°C The temperature was raised over 3 hours to perform an esterification reaction. After releasing the pressure, 0.92 parts of tetrabutyl titanate is added, and the inside of the system is gradually reduced in pressure, pressure-reduced to 5 mmHg over 20 minutes, and polycondensed at 260°C for 40 minutes under a vacuum of 0.3 mmHg or less. The reaction was performed to obtain a polyester resin. Table 1 shows the composition and physical properties of the obtained copolymerized polyester resin P-1.

Preparation examples of polyester resins P-2 to P-6

In the production example of the polyester resin P-1, the type and blending ratio of the monomer were changed to prepare the polyester resins P-2 to P-6. Table 1 shows the composition and the resin physical properties of the obtained co-polyester resin.

Preparation example of polyurethane resin U-1

In a reaction vessel equipped with a stirrer, condenser and thermometer, 1500 parts of polyester resin P-5, 1000 parts of P-6, 180 parts of neopentyl glycol (NPG), and 1,6-hexanediol (1,6HD) were added After putting in 50 parts, 2587 parts of ethyl diglycol acetate (EDGAC) was put, and it melt|dissolved in 85 degreeC. Thereafter, 810 parts of 4,4'-diphenylmethane diisocyanate (MDI) was added, followed by reaction at 85° C. for 2 hours, and then 0.5 parts of dibutyltin dilaurate as a catalyst was added thereto, and 4 at 85° C. more time to react. Next, the solution was diluted with 3440 parts of EDGAC, and the solution of polyurethane resin U-1 was obtained. The solid content concentration of the obtained polyurethane resin solution was 37 mass %. Thus, the obtained resin solution was dripped on the polypropylene film, it extended|stretched using the applicator made from stainless steel, and the thin film of the resin solution was obtained. This was left still in the hot-air dryer adjusted to 120 degreeC for 3 hours, the solvent was volatilized, then, the resin thin film was peeled from the polypropylene film, and the film-shaped dry resin thin film was obtained. The thickness of the dry resin thin film was about 30 μm. The dry resin thin film was used as a sample resin of polyurethane resin U-1, and the evaluation results of various resin properties are shown in Table 2.

Preparation example of polyurethane resin U-2

Polyurethane resin U-2 was prepared in the same manner as in Production Example of polyurethane resin U-1, except that polyester polyol, a compound having a group reactive with isocyanate, and polyisocyanate were replaced with those shown in Table 2. Table 2 shows the evaluation results of the resin properties of the polyurethane resin U-2.

DMBA: dimethylolbutanoic acid

1,6HD: 1,6-hexanediol

NPG: neopentyl glycol

MDI: 4,4'-diphenylmethane diisocyanate

Example 1

2381 parts (1000 parts of solid content conversion) of a solution in which polyester resin P-1 was dissolved in EDGAC/BDGAC (7:3) so that the solid content concentration was 42 mass%, 9000 parts of flaky silver powder 1, 108 parts of curing agent 1, 56 parts of a leveling agent, 36 parts of Additive 1, 92 parts of EDGAC as a solvent, and 40 parts of BDGAC were blended and passed through a chilled 3-roll kneader twice to disperse. Then, a 500-mesh (stainless steel mesh filter (wire diameter: 25 µm, eye size: 30 µm)) was attached to a paste filter (PF320A manufactured by Protech), and the paste was filtered. Then, after printing the obtained electrically conductive paste by a predetermined pattern, 130 degreeC x 30 minutes was dried, and the conductive thin film was obtained. The basic physical property was measured using this conductive thin film, and the laser etching process was then examined. Table 3 shows the evaluation results of paste and paste coating film and laser etching processability.

Examples 2-12, Comparative Examples 1-3

Examples 2 to 12 and Comparative Examples 1 to 3 were implemented by changing the resin and compounding of the conductive paste. Table 3 shows the formulation and evaluation results of the conductive paste. In the Example, favorable coating-film properties were obtained by heating at a relatively low temperature of 130° C. × 30 minutes in an oven and for a short time. Moreover, the adhesiveness to the ITO film|membrane and the adhesiveness after a wet heat environment test were also favorable.

In addition, in Table 3, the following things were used for binder resin, an electrically conductive powder, an additive, and a solvent.

Silver powder 1: flaky silver powder (D50: 0.5 μm)

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 Chuetsu Kokuen Kogyo Sho.

Hardener 1: Asahi Kasei Chemicals Co., Ltd. MF-B60X

Hardener 2: jER-828 manufactured by Mitsubishi Chemical

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

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

Dispersant 1: Big Chemie Japan Co., Ltd. Disperbyk2155

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

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

EDGAC: Ethyl diglycol acetate manufactured by Daicel Co., Ltd.

BDGAC: Butyldiglycol acetate manufactured by Daicel Co., Ltd.

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

The conductive paste for laser etching processing of the present invention can provide a conductive thin film that is excellent in wet heat environment reliability and can maintain the coating film durability as a conductive thin film while maintaining laser etching processing aptitude, for example, a portable device equipped with a touch panel It is useful as a conductive paste used for a telephone, a notebook computer, an electronic book, etc.

1a, 2a, 3a, 4a: Terminal A
1b, 2b, 3b, 4b: fine wire B
1c, 2c, 3c, 4c: Terminal C

Claims (11)

In the conductive paste for laser etching processing containing a binder resin (A) made of a thermoplastic resin, a metal powder (B) and an organic solvent (C), the binder resin (A) has a number average molecular weight of 5,000 to 60,000, and , a thermoplastic resin having a glass transition temperature of less than 60° C., and the binder resin (A) has an acid value of less than ^{50 equivalents/10 6 g.} According to claim 1, wherein the binder resin (A) is one or a mixture of two or more selected from the group consisting of a polyester resin, a polyurethane resin, an epoxy resin, a phenoxy resin, a vinyl chloride resin, and a cellulose derivative resin. Conductive paste for laser etching processing, characterized in that. delete The electrically conductive paste for laser etching processing of Claim 1 or 2 which filtered the electrically conductive paste. The conductive thin film formed from the electrically conductive paste for laser etching processes of Claim 1. The electroconductive laminated body by which the electroconductive thin film of Claim 5 and the base material are laminated|stacked. The conductive laminate according to claim 6, wherein the substrate has a transparent conductive layer. The electric circuit formed using the conductive thin film of Claim 5, or the electroconductive laminated body of Claim 6 or 7. An electric circuit having a wiring portion formed by irradiating a part of the conductive thin film according to claim 5 with a laser beam selected from a carbon dioxide laser, a YAG laser, a fiber laser, and a semiconductor laser, and removing a part of the conductive thin film. The electric circuit according to claim 9, wherein the conductive thin film is formed on a transparent conductive layer. A touch panel comprising the electric circuit according to claim 8 as a constituent member.

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