JP5286649B2 - Method for producing conductive film, conductive ink - Google Patents

Description

The present invention relates to a method for producing a conductive film using a conductive ink, and a conductive ink .

Conventionally, conductive inks used for the production of printed wiring boards, electromagnetic shielding materials, etc. can be broadly classified as follows: (1) Good conductivity can be achieved by fusing silver particles together, but the base material is limited to ceramics, etc. (2) Can be widely applied from glass and epoxy printed circuit board to film, but in order to obtain conduction by contact between metal particles due to thermal shrinkage during binder curing, electrical resistance is There is a relatively high polymer type conductive ink.
All of them require relatively long heating exceeding 120 ° C, are difficult to apply to heat-sensitive substrates, and require several tens of minutes or more to complete the curing, so there are problems related to productivity and manufacturing process. .

As these solutions, there have been proposed many conductive inks that do not substantially require heating and can be cured by active energy rays such as ultraviolet rays (UV) and electron beams.
For example, Patent Document 1 discloses that an electron beam curable and heat curable resin and a conductive coating composition comprising a conductive filler are combined with electron beam irradiation and heating to achieve a high degree of heat resistance and adhesion. A method for curing a highly reliable conductive paint having moisture resistance is disclosed.

  In particular, cationically curable inks have a long lifetime of cation-active species once generated, can be cured (dark reaction) in areas that are not directly irradiated with energy rays, and have a high density of conductive particles. The ink can be easily cured, and the resulting cured coating film has excellent adhesion to substrates such as metal, glass, silicon substrate, plastic film, scratch resistance, solvent resistance, weather resistance, heat It is expected as a next-generation conductive ink that completely covers the drawbacks of curable conductive ink.

For example, Patent Document 2 discloses (a) an alicyclic epoxy resin, (b) a conductive powder, (c) an energy ray-sensitive cationic polymerization catalyst that can release a Lewis acid upon receiving energy rays, and (d). A conductive resin composition containing a heat-sensitive cationic polymerization catalyst and capable of being sufficiently cured by irradiation with energy rays and / or heating at a relatively low temperature for a short time even when the conductive powder content is 70 to 90 wt% of the entire composition. Is disclosed.
Patent Document 3 uses a solvent-free polymer resistance paste composition comprising a cycloaliphatic epoxy resin, a cationic photoinitiator, a thermosetting catalyst, and conductive particles, and uses photocuring and thermosetting together. By doing so, it achieves sufficient film curability without causing surface cracking due to evaporation of the solvent, peeling of the circuit pattern from the electrode due to volume reduction, contact breakdown, etc. like conventional solvent-added polymer type conductive paste Technology is disclosed.
Patent Document 4 includes a cation-curable solvent-free epoxy resin, an addition product of epoxide and phenol, a cationic photopolymerization initiator, a cationic thermal initiator, conductive particles, UV-initiated cationically curable conductive reaction resin mixtures are disclosed.
Patent Document 5 discloses a conductive powder, a cationic curable resin composition, a coating property / flexibility improving material, as a solventless conductive paste having low resistance and excellent coating properties and bending resistances. In addition, a conductive paste characterized by having a dispersibility improving material as an essential component is disclosed.
Japanese Patent Laid-Open No. 02-240168 Japanese Patent Publication No. 05-059931 JP 2000-290583 A Special table 2000-501151 gazette JP 2002-109959 A

  However, the active energy ray-curable conductive ink has a problem that the contact between the conductive particles cannot be sufficiently obtained and the conductivity is low.

The present invention has been made in view of the above circumstances, and obtains a conductive film having substantially the same or better conductivity as a thermosetting polymer type conductive ink, without substantially heating the coating film. An object of the present invention is to provide a conductive film manufacturing method and a conductive ink .

In order to solve the above-mentioned problems, the present invention reduces the active energy ray by irradiating a coating film made of conductive ink containing active energy ray-reducible silver compound particles and an active energy ray-curable compound with active energy rays. Provided is a method for producing a conductive film, wherein the conductive silver compound particles are reduced to silver to develop the conductivity of the coating film and the active energy ray-curable compound is cured.

According to the present invention, the active energy ray-reducible silver compound in the conductive ink is reduced by active energy ray irradiation to exhibit high conductivity, and at the same time, the active energy ray-curable compound is cured by the active energy ray. Thus, a cured coating film having conductivity can be produced without heating.
It is presumed that this is because active silver is produced by reduction and the particles are in strong contact with each other, but of course this does not limit the present invention. The active energy rays referred to here indicate energy rays such as infrared rays, visible rays, ultraviolet rays, electron beams, laser beams, etc., and according to the present invention, the type of reducing silver compound to be applied and the use of conductive films. You can choose according to your needs.

The present invention is described in further detail below.
In this invention, a coating film is formed using the conductive ink which contains an active energy ray reducible silver compound and an active energy ray curable compound as an essential component. Here, the active energy ray-reducible silver compound refers to a compound that is reduced directly and indirectly in the presence of an accelerator or in the presence of an accelerator to precipitate silver. For example, inorganic silver compounds such as silver oxide, silver halide, silver carbonate, and silver phosphate, organic silver salts such as silver stearate, silver palmitate, silver behenate, piperazine and piperidine compounds and silver salts, and silver Complexes can be used. Examples of reduction accelerators that can be added as necessary include polyhydric alcohols such as glycerin, ethylene glycol, and polyethylene glycol, reducing sugars such as glucose, fructose, and lactose, sodium borohydride, dimethylamine borane, hydroquinone, ascorbic acid, Hypophosphorous acid can be used. Among them, silver oxide can be suitably applied to the present invention because it is easily reduced by UV light to produce active silver.
There is no restriction | limiting in the shape when containing an active energy ray reducible silver compound in electroconductive ink, Particle | grains, such as a granular form, flake shape, and needle shape, can be used. As such particles, particles coated with an active energy ray-reducible silver compound may be used in addition to the active energy ray-reducible silver compound particles.

In the present invention, when using particles whose surfaces are coated with an active energy ray-reducible silver compound (particles having a surface having an active energy ray-reducible silver compound layer), the material serving as the core of the coated particles is gold, Conductive metal particles such as silver, copper, aluminum, tin, nickel, and platinum are preferable, but are not particularly limited thereto.
Moreover, as active energy ray-reducible silver compound-containing particles, silver particles having silver oxide attached or coated on a part or the whole of the particle surface can be suitably used. Silver particles with silver oxide deposited or coated on the surface are oxidized by silver oxide surface from silver to silver oxide by the partial oxidation treatment of the surface of silver particles, and silver oxide is deposited on the surface of silver particles Can be prepared. For example, by adding an aqueous silver nitrate solution to a slurry in which silver particles are dispersed in water, and further adding an alkali metal salt such as sodium hydroxide or potassium hydroxide to neutralize the silver nitrate, the silver oxide fine particles are separated from the surface of the silver particles. Thus, silver particles having silver oxide adhered to the surface or coated on the entire surface can be obtained.

The volume average particle diameter of these active energy ray-reducible silver compound particles or active energy ray-reducible silver compound-containing particles (hereinafter sometimes simply referred to as “particles”) is preferably 0.05 to 20 μm, more preferably. It is about 0.05 to 10 μm. As these particles, two or more kinds of particles having different volume average particle diameters may be combined, or two or more kinds of granular and flaky silver powders may be combined.
When silver oxide is applied as the active energy ray-reducible silver compound particles, it is particularly preferable to use reducible silver compound particles having an average particle diameter of 5 μm or less because a conductive coating film having excellent conductivity can be obtained.

  In particular, a highly conductive film can be obtained by applying silver particles that are partially or entirely coated with silver oxide. In the silver particles, the silver oxide content is preferably 1% by mass or more (silver content 99% by mass or less), and the silver oxide content is particularly preferably 5% by mass or more (silver content 95% by mass or less). In order to impart high conductivity to the film, it is desirable to have a certain amount of metallic silver inside the particles, and the silver oxide content is preferably 30% by mass or less (the silver content is 70% by mass or more). The silver oxide content is particularly preferably 20% by mass or less (silver content 80% by mass or more). The preferable range of the silver oxide content of the silver particles surface-treated with silver oxide is 1 to 30% by mass, and the more preferable range is 5 to 20% by mass.

In the present invention, in order to improve the dispersibility of the particles in the resin, etc., a surfactant is adsorbed on the surface of the above-mentioned particles (hereinafter, this may be referred to as “surfactant surface-treated particles”). Is preferably used. As a result, the stability with time of the conductive ink and the conductivity of the cured film can be improved, and fine fine lines can be easily formed by a printing method. In addition, since the surfactant can be efficiently adsorbed on the particles, the amount of the surfactant added for stable dispersion of the particles can be reduced. According to the study by the present inventors, the smaller the amount of surfactant added, the better for improving the photocationic curability of the conductive ink.
The surfactant surface-treated particles used in the present invention include (1) a dispersion step in which particles are dispersed in a dispersion solvent in the presence of a surfactant to produce a dispersion, and (2) the dispersion is vacuumed. It can be manufactured by a manufacturing process having a drying process for freeze-drying.
Thereby, since aggregation of particles is prevented and dispersibility in the resin is improved, it is possible to maintain a state where the particles are stably dispersed with fine particles (primary particles). Therefore, it is possible to prevent unnecessary aggregates from being generated due to fusion of particles during reduction, and no problem in fine printing occurs.
Here, the surfactant used for the surface treatment of the particles in the dispersion step can be selected from many types of surfactants that are usually used, and can be used as an anionic surfactant or a nonionic surfactant. Surfactants, cationic surfactants and amphoteric surfactants.

(Surfactants of alkylamines and alkylamine salts)
Alkylamines and alkylamine salts are suitable as the surfactant used in the present invention. Alkylamine-based nonionic surfactants and alkylamine salt-based cationic surfactants are effective even when used alone, but the dispersibility of the particles is improved by using both in particular. It becomes good and the effect is remarkable. When an alkylamine-based surfactant and an alkylamine salt-based cationic surfactant are used in combination, the mixing ratio of the alkylamine-based and alkylamine salt-based systems is in the range of 1:20 to 1: 5. preferable.

  As the alkylamine surfactant, a polyoxyalkylene alkylamine type surfactant is preferable, and a polyoxyethylene alkylamine type surfactant is more preferable. Among them, those having the following chemical structure (1) are more preferable.

  In the formula (1), a and b are each an integer of 1 to 20, and R represents an alkyl group or an alkylaryl group having 8 to 20 carbon atoms.

  On the other hand, alkylamine salt surfactants are preferably alkylamine acetates, more preferably those having the following chemical structure (2).

  In formula (2), R represents an alkyl group having 8 to 20 carbon atoms or an alkylaryl group.

  In the formula (1) and the formula (2), the alkyl group having 8 to 20 carbon atoms may be a linear alkyl group or a branched alkyl group. For example, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, Examples include lauryl group, tetradecyl group, myristyl group, hexadecyl group, cetyl group, octadecyl group, stearyl group, and eicosyl group. Examples of the alkylaryl group having 8 to 20 carbon atoms include alkylphenyl groups such as octylphenyl group, nonylphenyl group, and dodecylphenyl group. The alkyl part of the alkylaryl group may be a linear alkyl group or a branched alkyl group.

(Phosphate-based surfactant)
As the surfactant used in the present invention, a phosphate-based surfactant can also be suitably used.
The phosphate ester surfactant used in the present invention is a surfactant mainly composed of phosphate monoester or phosphate diester. The phosphate ester surfactant as the main component is preferably a phosphate ester of polyoxyalkylene alkyl ether, and more preferably has a chemical structure represented by the following general formula (3).

  In formula (3), R represents an alkyl group having 1 to 20 carbon atoms or an alkylaryl group, n is an integer of 1 to 20, and x is 1 or 2.

  In the formula (3), the alkyl group having 1 to 20 carbon atoms may be a linear alkyl group or a branched alkyl group. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group , Heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, lauryl group, tetradecyl group, myristyl group, hexadecyl group, cetyl group, octadecyl group, stearyl group, eicosyl group and the like. Examples of the alkylaryl group having 20 or less carbon atoms include alkylphenyl groups such as octylphenyl group, nonylphenyl group, and dodecylphenyl group. The alkyl part of the alkylaryl group may be a linear alkyl group or a branched alkyl group.

  In addition, it is preferable that the carbon number of R is 1-10, n is 1-10, and the sum of the carbon number of R and n is 7-15. The weight average molecular weight of the phosphate ester surfactant is preferably 100 to 10,000, and more preferably 150 to 5,000. The P content is preferably 0.5% to 10%, particularly preferably 2% to 6%.

(Dispersing solvent)
In the dispersion step, a mixture of active energy ray-reducible silver compound particles and a surfactant is added to a dispersion solvent and applied to a stirrer or a disperser. As a result, the active energy ray-reducible silver compound particles are crushed into substantial primary particles and mixed with the surfactant. The range of the solid content concentration in the dispersion of active energy ray-reducible silver compound particles is preferably 0.5 to 80%, particularly preferably 1 to 50%. The dispersion solvent used for dispersing the active energy ray-reducing silver compound particles is not particularly limited as long as it can dissolve the surfactant to be used, but water is preferably used.
In the dispersion treatment of the active energy ray-reducible silver compound particles by the dispersion solvent, it is preferable that the active energy ray-reducible silver compound particles are blended after the surfactant is blended and sufficiently dissolved in the dispersion solvent. The crushing of active energy ray-reducible silver compound particles to substantially primary particles can be realized by an appropriate dispersion method such as a ball mill.

(2) Drying step In the dispersion solvent, the active energy ray-reducible silver compound particles are substantially dispersed to primary particles in the presence of a surfactant, and then the dispersion solvent is removed from the dispersion liquid by a vacuum freeze-drying method. Do. The dispersion is pre-frozen by freezing and vacuum drying below the freezing point of the dispersion solvent at atmospheric pressure, and the degree of vacuum is controlled at a pressure lower than the vapor pressure of the dispersion solvent at the freezing point to remove only the dispersion solvent from the frozen solid mixture. Sublimation can be removed. In vacuum freeze-drying, the dispersion solvent is sublimated and evaporated at a low temperature, so that partial component concentration and partial component change due to mass transfer do not substantially occur during drying.
In a dispersion liquid in which a dispersion solvent, active energy ray-reducible silver compound particles, and a surfactant are mixed, the surfactant is generally localized near the surface of the silver compound particles. Vacuum freeze-drying effectively adsorbs the surfactant localized near the surface of the silver compound particles on the surface, and obtains dry particles in which the surfactant is substantially uniformly adsorbed on the surface of the silver compound particles. . Therefore, the surface of the particles can be effectively treated with a very small amount of surfactant by applying the freeze-drying method.
In the case of a dispersion using water as a dispersion solvent (a dispersion containing active energy ray-reducible silver compound particles, water, and a surfactant), it is pre-frozen to 0 ° C. or less at atmospheric pressure, and theoretically 0 What is necessary is just to control a vacuum degree so that the vapor pressure of water 4.5 degreeHg (= 600 Pa) may not be exceeded. In consideration of the drying speed and ease of control, it is preferable to reduce the temperature to 1 mmHg (= 133.32 Pa) or less and to the melting point (freezing point) at the vapor pressure.

(Active energy ray-curable compound)
In addition, an active energy ray-curable compound that is cured by irradiation with active energy rays is added to the conductive ink used in the present invention. In the present invention, in order to avoid gelation at the time of curing, it is preferable to use a photocationically polymerizable compound as the active energy ray-curable compound.
As the photocationically polymerizable compound, any compound that can be photocationically polymerized can be appropriately selected from known ones. For example, alicyclic epoxy compounds, oxetane compounds, vinyl ether compounds, cation polymerizable acrylic compounds (cations) Acrylic compounds having a polymerizable group), various polyols and polyol polyesters.
In the present invention, it is preferable that at least an alicyclic epoxy compound is an essential component as the photocationically polymerizable compound. In particular, it is preferable to use an alicyclic epoxy compound and an oxetane compound as essential components. By adding the oxetane compound, the cured coating film strength can be improved.

(Cationic polymerization initiator)
As the cationic polymerization initiator added together with the photocationically polymerizable compound, known ones can be used, and examples include diaryliodonium salts, triarylsulfonium salts, aromatic diazonium salts, and iron arene complexes. Among these, diaryliodonium salts are preferable because they are excellent in curability (curing speed, curing depth, coating film adhesion). As the counter anion when these cationic polymerization initiators are onium salt compounds, hexafluoroantimonate anion, hexafluorophosphate anion, tetrakis (pentafluorophenyl) borate anion and the like are preferable.
When photocationic polymerization is performed, a photosensitizer such as a phenothiazine derivative, a xanthone derivative, a thioxanthone derivative, an aminobenzoic acid derivative, a polycyclic aromatic compound such as anthracene, phenanthrene, or perylene, or a combination thereof is added. Furthermore, a polyhydric alcohol compound or the like that acts as a proton supply source may be added.

  Conductivity from the above active energy ray-reducible silver compound particles (or surface-treated particles thereof), a photocationic polymerizable compound, a cationic polymerization initiator, and other components that can be added as required (details will be described later). The method for producing the ink can be performed by a general method. For example, with 2 rolls, 3 rolls, ball mill, sand mill, pebble mill, tron mill, sand grinder, seg barrier striker, high speed impeller disperser, high speed stone mill, high speed impact mill, kneader, homogenizer, ultrasonic disperser, etc. Dispersion is mentioned.

(solvent)
The conductive ink used in the present invention may contain a solvent in order to adjust the printability of the conductive ink and the dispersibility of the active energy ray reducing silver compound particles. Examples of the solvent that can be used in the present invention include alcohols such as methanol, ethanol, n-propanol, benzyl alcohol, and terpineol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, isophorone, acetylacetone, and propylene carbonate; N, N— Amides such as dimethylformamide and N, N-dimethylacetamide; ethers such as tetrahydrofuran, dioxane, methyl cellosolve, diglyme, methoxypropanol, ethyl carbitol, butyl carbitol; methyl acetate, ethyl acetate, diethyl carbonate, TXIB (1 -Isopropyl-2,2-dimethyltrimethylenediisobutyrate), esters such as carbitol acetate and butyl carbitol acetate; and esters such as dimethyl sulfoxide and sulfolane. Foxides and sulfones; aliphatic halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, 1,1,2-trichloroethane; benzene, toluene, o-xylene, p-xylene, m-xylene, monochlorobenzene, di And aromatics such as chlorobenzene. In particular, glycol ethers and glycol ether acetates such as ethyl carbitol, butyl carbitol, carbitol acetate, and butyl carbitol acetate are preferable because of their moderate volatility and solubility of monomers and resins.
These solvents are not limited to those listed here, and can be used alone or in admixture of two or more. The amount of the solvent used varies depending on the coating method and the printing method, and the amount used may be appropriately selected.

(Binder resin)
To the conductive ink used in the present invention, a binder resin (binder resin) is further added in order to improve the dispersion stability of the particles contained in the ink and to improve the adhesion to the substrate. Also good. Binder resins that can be used in the present invention include acrylic resin, butyral resin, polyvinyl alcohol resin, acetal resin, phenol resin, urea resin, vinyl acetate emulsion, polyurethane resin, polyester resin, polyvinyl acetate resin, epoxy resin, melamine Resin, alkyd resin; and cellulose resins such as nitrocellulose, ethyl cellulose, cellulose acetate butyrate, and the like. These binder resins can be used alone or in admixture of two or more.
When forming a coating film by this invention, when applying electroconductive ink as screen printing ink, it is preferable to contain a cellulose resin, and ethyl cellulose is mentioned suitably as a cellulose resin. Ethyl cellulose is compatible with aliphatic epoxies and oxetane compounds, and by adding ethyl cellulose to the cationically polymerizable compound, it can impart appropriate fluidity to the ink, improving ink plate permeability, and after printing. It is possible to improve printing characteristics such as improved ink leveling and prevention of blurring of printed patterns (fine pattern can be formed). Furthermore, the strength of the cured film is improved, and surprisingly, the conductivity of the cured film is improved.

(Other ingredients that can be added to ink)
In addition, the conductive ink used in the present invention includes non-reactive compounds, antifoaming agents, leveling agents, lubricants, plasticizers; antioxidants such as methoxybenzene and dibutylhydroxytoluene; ethanolamine and triethanol. Polymerization inhibitors such as amines; UV absorbers, flame retardants, pigments, dyes, rheology modifiers and the like can be used in combination as appropriate.

(Formation method of coating film)
As a method of forming a coating film using a conductive ink, in addition to known and commonly used printing methods such as screen printing, gravure printing, flexographic printing, lithographic printing, and reversal printing, it can be by dispenser, dipping, coating, etc. . Examples of the substrate include polyethylene terephthalate film (PET film), polyimide film (PI film), green sheet (inorganic substrate), SiO ₂ , glass, metal, and the like. Moreover, although the thickness of a printing coating film changes with printing methods, the range with a wet thickness of printed matter of 1-20 micrometers is preferable, and the thickness of 1-10 micrometers is especially preferable. In order to increase the electric resistance (volume resistivity) per unit volume after the printed matter is dried, press or calender treatment may be performed to such an extent that the substrate is not significantly deformed.

Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited only to these Examples. Unless otherwise specified, “%” and “part” are based on mass.
The coating thickness was measured with an ANRITSU film thickness measuring device “K-402B”. The volume resistivity was measured according to JIS K-7194 by Mitsubishi Chemical's resistivity meter “Loresta-EP MCP-T360” by the four deep needle method.

Example 1
The surface was coated with 60 g of flaky silver powder AgC-209 manufactured by Fukuda Metal Foil Powder Co., Ltd. having a 50% average particle diameter of about 4.5 μm and 5% silver oxide manufactured by Mitsui Metals Co., Ltd. having a center diameter of about 0.3 μm. 20 g of silver powder FHD, 8 g of 10% aqueous solution of coconut amine acetate as a surfactant (1% of surfactant is added to the total amount of the silver particles + silver oxide-coated silver particles), 100 g of water as a dispersion solvent, and 800 g of zirconia beads having a diameter of 2 mm were placed in a 500 cc polyethylene bottle and kneaded for about 4 hours using a ball mill to obtain a silver oxide-containing silver particle dispersion (a1).
The obtained dispersion (a1) of silver oxide-containing silver particles was transferred to a flat tray and vacuum lyophilized. As the freeze dryer, “DFM-05AS” manufactured by Nippon Vacuum Co., Ltd. was used. In the vacuum freeze-drying, first, a dispersion of silver oxide-containing silver particles is frozen in an atmosphere of about −40 ° C., then the vacuum pressure is kept at 7 to 10 Pa, and the frozen ice is sublimated, and the surface-treated surface-treated dry silver oxide-containing silver particles ( b1) was obtained.

Using a three-roll mill, 80.8 g of the above surfactant surface-treated dry silver oxide-containing silver particles (b1), 3 g of ethylcellulose having a molecular weight of about 80,000 (Etocel manufactured by Nisshin Kasei Co., Ltd.), an alicyclic epoxy monomer (Daicel) Chemical Co., Ltd. Celoxide 2021P) 9.5 g, Oxetane compound (OXT-221 manufactured by Toagosei Co., Ltd.) 4.5 g, Diethylthioxanthone 0.2 g, Diaryliodonium salt-based polymerization initiator (Irgacure 250 manufactured by Ciba Specialty Chemicals) ) 2 g and 0.8 g of a dispersant (Disperbyk-2001, manufactured by Big Chemie Japan) were kneaded well to obtain the conductive ink (c1) of Example 1.
The surfactant-treated silver oxide-containing silver particles are uniformly dispersed in the obtained conductive ink (c1). The coarse particles of 5 μm or more are obtained in the obtained ink by a grindometer manufactured by Toyosei Seiko Co., Ltd. I confirmed that there was no.

Using the obtained conductive ink (c1), a screen plate “ST400B MC-9” (emulsion film thickness 4 μm) manufactured by Mesh Co., Ltd. was used to produce a printed matter of 80 mm × 50 mm on a 50 μm-thick PET film. This printed matter was cured at a total UV irradiation amount of 1800 mJ / cm ² using an iGraphic Metal Halide UV lamp (120 W / cm) to obtain a cured coating film (d1) having an average coating thickness of 14 μm. The volume resistivity of the obtained cured coating film (d1) was 7.6 × 10 ⁻⁵ Ω · cm.

(Example 2)
85 g of silver powder FHD with a surface coating of 5% silver oxide manufactured by Mitsui Kinzoku Co., Ltd. having a center diameter of about 0.3 μm, and a polyoxyalkylene alkyl ether having a phosphorus content of 4.4% as a phosphate ester surfactant 8.5 g of 10% aqueous solution of phosphate ester (weight average molecular weight of about 1700, HLB of about 12) (1% of surfactant is added to the total amount of silver particles + silver oxide coated silver particles) as a dispersion solvent 100 g of water and 800 g of zirconia beads having a diameter of 2 mm were placed in a 500 cc polyethylene bottle and kneaded for about 4 hours using a ball mill to obtain a silver oxide-containing silver particle dispersion (a2).
The obtained dispersion (a2) of silver oxide-containing silver particles was subjected to vacuum freeze-drying treatment in the same manner as in Example 1 to obtain surfactant surface-treated dry silver oxide-containing silver particles (b2).

Using a three-roll mill, 85.85 g of the surfactant-treated dry silver oxide-containing silver particles (b2), 8 g of an alicyclic epoxy monomer (Celoxide 2021P manufactured by Daicel Chemical Industries, Ltd.), an oxetane compound (manufactured by Toagosei Co., Ltd.) OXT-221) 4.5 g, diethylthioxanthone 0.2 g, diaryliodonium salt polymerization initiator (Irgacure 250 manufactured by Ciba Specialty Chemicals) 2 g, dispersant (Big Chemy Japan Disperbyk-2001) 0.3 g The conductive ink (c2) of Example 2 was obtained by kneading.
The surfactant-treated silver oxide-containing silver particles are uniformly dispersed in the obtained conductive ink (c2). This is about 0.8 μm in the obtained ink using a grindometer manufactured by Toyoe Seiko Co., Ltd. It was confirmed that there was no coarse particles.
The film thickness and volume resistivity of the cured coating film (d2) obtained by screen printing film formation and UV curing were measured in the same manner as in Example 1 with the obtained conductive ink (c2). The plate separation of the conductive ink (c2) at the time of printing is good, the leveling property is excellent, the surface of the UV cured film is excellent in smoothness, and the cured coating film (d2) having an average film thickness of about 6 μm I was able to get it. The volume resistivity of the cured coating film (d2) was 3.2 × 10 ⁻⁵ Ω · cm.

(Comparative Example 1)
85 g of pure silver powder FHD made by Mitsui Kinzoku Co., Ltd. with a center diameter of about 0.3 μm and a polyoxyalkylene alkyl ether / phosphate ester having a phosphorus content of 4.4% as a phosphate ester surfactant (weight average molecular weight 8.5 g of a 10% aqueous solution (about 1700, HLB about 12) (adding 1% of a surfactant to the pure silver particles), 100 g of water as a dispersion solvent, and 800 g of zirconia beads having a diameter of 2 mm in a 500 cc polyethylene bottle The mixture was kneaded for about 4 hours using a ball mill to obtain a dispersion of pure silver particles (a3).
The obtained dispersion liquid (a3) of pure silver particles was subjected to vacuum freeze-drying treatment in the same manner as in Example 1 to obtain surfactant surface-treated dry pure silver particles (b3).

Using a three-roll mill, 85.85 g of the surfactant surface-treated dry pure silver particles (b3), 8 g of an alicyclic epoxy monomer (Celoxide 2021P manufactured by Daicel Chemical Industries, Ltd.), an oxetane compound (OXT-221 manufactured by Toagosei Co., Ltd.) ) 4.5 g, 0.2 g of diethylthioxanthone, 2 g of diaryliodonium salt polymerization initiator (Irgacure 250 manufactured by Ciba Specialty Chemicals), and 0.3 g of a dispersant (Bicchemy Japan Disperbyk-2001) 0.3 g. As a result, a conductive ink (c3) of Comparative Example 1 was obtained.
Using the conductive ink (c3) of Comparative Example 1, the film thickness and volume resistivity of the cured coating film (d3) obtained by screen printing film formation and UV curing were measured in the same manner as in Example 1. The obtained cured coating film (d3) of Comparative Example 1 had a film thickness of about 9 μm and a volume resistivity of 8.6 × 10 ⁻³ Ω · cm.

In Examples 1 and 2, since the surfactant surface-treated particles prepared from particles containing silver oxide in the conductive ink were used, when the coating film of the conductive ink was cured without heating by UV irradiation, the silver particles It is considered that the contact could be made well.
On the other hand, in the cured coating film obtained in Comparative Example 1, the volume resistivity was significantly increased as compared with the Examples, but this was a surfactant produced from pure silver particles containing no silver oxide in the conductive ink. It is considered that the contact between the silver particles deteriorated when the coating film of the conductive ink was cured without heating by UV irradiation using the surface-treated particles.

  The present invention is applied to printed wiring used for electronic devices, various conductive adhesives, resistors, capacitors and inductor electrodes, non-contact IC tag antennas, plasma display discharge electrodes and electromagnetic shields, mobile phones, etc. The present invention can be used for the production of electronic materials including various conductive films, such as the generation of static electricity removal.

Claims (13)

  The active energy ray-reducible silver compound particles are reduced to silver by irradiating the active energy ray-reduced silver compound particles and the coating film made of the conductive ink containing the active energy ray-curable compound with active energy rays. A method for producing a conductive film, wherein the conductive energy of the coating film is expressed and the active energy ray-curable compound is cured.   The electroconductive ink according to claim 1, wherein the electroconductive ink is a cation curable electroconductive ink containing active energy ray-reducible silver compound particles, a photo cationic polymerizable compound, and a cationic polymerization initiator as essential components. A method for producing a membrane.   The manufacturing method of the electroconductive film | membrane of Claim 2 containing an alicyclic epoxy compound as said photocationic polymerizable compound.   The method for producing a conductive film according to claim 3, further comprising an oxetane compound as the photocationically polymerizable compound.   A surface-active agent is applied to the surface of the active energy ray-reducing silver compound particles by subjecting the dispersion in which the active energy ray-reducible silver compound particles are dispersed in a dispersant to a vacuum freeze-drying treatment in the presence of the surfactant. The manufacturing method of the electroconductive film of any one of Claims 1-4 which adsorb | suck.   The method for producing a conductive film according to claim 1, wherein the active energy ray-reducible silver compound particles are silver particles in which silver oxide is attached or coated on a part or the whole of the particle surface. .   The method for producing a conductive film according to claim 6, wherein a silver oxide content of silver particles having silver oxide adhered or coated on a part or the entire surface of the particle surface is 1% by mass or more.   The method for producing a conductive film according to claim 1, wherein the conductive ink further contains a cellulose resin. By vacuum freeze-drying in the presence of a surfactant dispersion prepared by dispersing the active energy ray reducible silver compound particles in the dispersant in-phosphate ester, wherein the active energy ray reducible silver compound particles The method for producing a conductive film according to claim 5 , wherein the surfactant is adsorbed on the surface of the conductive film. By vacuum freeze-drying the dispersion liquid dispersed in the dispersant the active energy ray reducible silver compound particles in the presence of a surfactant which is a A Rukiruamin and / or alkyl amine salts, the active energy ray reduction The method for producing a conductive film according to claim 5 , wherein the surfactant is adsorbed on the surface of the conductive silver compound particles . A conductive ink used in the method for producing a conductive film according to claim 1,
A dispersion containing active energy ray-reducible silver compound particles and an active energy ray-curable compound, in which the active energy ray-reducible silver compound particles are dispersed in a dispersion solvent in the presence of a surfactant, is subjected to a vacuum freeze-drying treatment. Thus, a surfactant is adsorbed on the surface of the active energy ray-reducing silver compound particles.   The conductive ink according to claim 11, wherein the conductive ink is a cationic curable conductive ink containing a photo cationic polymerizable compound as an active energy ray curable compound and further containing a cationic polymerization initiator. The conductive ink according to claim 11 or 12, wherein the active energy ray-reducible silver compound particles are silver particles in which silver oxide is attached or coated on a part or the whole of the particle surface.