JP2012246433A - Conductive ink, laminate with conductive pattern, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide conductive ink of a low-temperature treatment type which continuously forms a conductive pattern, which is highly precise in the horizontal direction, also flat in the thickness direction, excellent in flexibility, little in warpage, and excellent in durability, by high-speed screen printing, and is excellent in resistance-value stability.SOLUTION: The conductive ink has two kinds of conductive particles of different tap density by a specific ratio, uses a specific bisphenol type epoxy resin with a specific acrylic elastomer as a binder resin by a specific ratio, and further has a specific amount of a metallic chelate and a curing agent.

Description

  The present invention relates to a conductive ink, a laminate with a conductive pattern obtained using the conductive ink, and a method for producing the same.

  In general, an etching method and a printing method are known as an electronic component, a thin film forming unit for electromagnetic wave shielding, or a conductive circuit forming unit. The etching method means a processing technique in a broad sense including a surface treatment of a metal by dissolving or removing the surface or shape of the metal chemically or electrochemically. Etching is a kind of chemical processing, and is mainly performed to obtain a desired pattern shape on a metal film. However, the process is generally complicated and waste liquid treatment is required in the subsequent process, so the cost is also high. There are many problems. In addition, since the conductive circuit formed by the etching method is formed of a metal material such as aluminum or copper, there is a problem that the conductive circuit is weak against physical impact such as bending.

  Therefore, in order to solve these problems and form a conductive circuit at a lower cost, conductive ink has attracted attention. A conductive circuit can be easily formed by printing conductive ink. Furthermore, since electronic components can be expected to be smaller and lighter, improve productivity, and reduce costs, research and development on conductive ink has been energetically performed, and many proposals have been made (for example, Patent Documents 1 to 3). 16).

Patent Document 1 describes a method for manufacturing a thermocompression bonding member in which a solvent absorption layer is formed and a conductive paste is screen-printed thereon.
In Patent Document 2, a high-definition conductive circuit is printed by using a conductive ink containing spherical or granular metal particles having a specific average particle size and a maximum particle size on a substrate having a roughened surface. Techniques for forming the are disclosed.
Patent Document 3 discloses a screen printing ink that controls a TI value (thixo index, thixo index) in order to form a high-definition color filter or the like.

Patent Document 4 discloses that 60 to 90% by weight of conductive powder having a tap density in the range of 2.5 to 6 g / cm ³ and an average particle size in the range of 0.02 to 1 μm. A conductive ink for use in lithographic offset printing is disclosed that contains an organic component in the range of 10 to 40% by weight.
In Patent Document 5, a copper powder having an average particle diameter of 20 μm or less or a silver-plated copper powder, a thermoplastic resin, an additive, and a silane coupling agent as an adhesion improver are added to the solid content of the conductive paint. A conductive paint dispersed in an organic solvent contained in the range of 001 to 5.0% by weight is disclosed.

  Furthermore, in Patent Document 6, in order to provide a conductive paste having high adhesion to a polyimide substrate and good bending resistance and solvent resistance, an aluminum compound and a silane coupling agent are used. A conductive paste using a binder resin containing two or more types is disclosed.

  In Patent Document 7, when the electric resistance, migration resistance, and resistance change rate of a conductor after applying an electric field for a long time under high temperature and high humidity, and exhibiting silver or silver white, the base material is a PET film. In order to provide a conductive paste that does not cause shrinkage / deformation of the base material, a conductive paste containing a thermoplastic resin containing OH groups, scaly composite conductive powder, scaly silver powder, and a solvent is disclosed.

Patent Document 8 discloses a conductive paste containing a flat conductive powder, an irregular shaped conductive powder, a thermoplastic synthetic resin, and a solvent in order to provide a conductive paste capable of imparting good conductivity. As examples of thermoplastic synthetic resins, it is disclosed that epoxy resins, acrylic resins, phenoxy resins, ethyl cellulose, polyvinyl butyral, and the like can be used.
Furthermore, Patent Document 9 discloses a conductive paste in which an epoxy equivalent exceeds 500 and an epoxy resin having a molecular weight exceeding 10,000 is dissolved in a solvent having a boiling point of 200 to 250 ° C. and a conductive filler is dispersed. Yes.

Patent Document 10 discloses a conductive paste made of conductive powder, a polyester resin and an isocyanate compound and imparted with thermal shock resistance and bending resistance.
Patent Document 11 discloses a conductive paste having excellent bending resistance, which contains conductive metal powder, urethane-modified polyester resin, and blocked isocyanate.

In Patent Document 12, a conductive filler mainly composed of silver powder and silver-coated copper powder and a binder resin are essential components, and the content of the silver-coated copper powder is 1% by weight to 40% by weight of the entire conductive filler. % Composition is proposed.
Patent Document 13 discloses a material composed of a conductive filler, a binder made of a composite resin of an epoxy-modified polyester resin and a phenol resin, and a solvent.
Patent Document 14 discloses a conductive material containing copper powder, at least one resin selected from phenolic resins, epoxy resins, and acrylic resins, a copper chelating agent, and glycerin in a specific ratio. A sex paste is disclosed.
Patent Document 15 discloses a conductive adhesive paste containing metal powder in which the surface of copper powder or copper alloy powder is partially coated with silver, and an epoxy resin and imidazole in a specific ratio.
Patent Document 16 discloses a conductive paste containing a conductive filler specified by an X-ray diffraction method and a binder resin.

Japanese Patent Application Laid-Open No. 06-68924 International Publication No. 2003/103352 JP 2003-238876 A JP 2001-234106 A JP 2005-29639 A JP 2006-310022 A JP 2003-68139 A JP 2003-331648 A JP-A-2005-183301 JP 2006-100081 A JP 2010-118280 A JP 2007-227156 A JP 2003-68141 A JP-A 62-160603 JP 2009-245938 A JP 2005-293551 A

  However, the characteristics and performance required for conductive ink are severe, and more excellent conductive ink is required.

The conductive ink can be classified into a high-temperature firing type as in Patent Document 4 and a low-temperature treatment type. The high-temperature firing type applies a high temperature to the base material and the electronic component when forming the conductive pattern, and thus easily damages the electronic component and causes problems due to heat shrinkage. For this reason, in recent years, the demand for a low-temperature treatment type is rapidly increasing.
Moreover, simplification of a manufacturing process is calculated | required from a viewpoint of the product yield improvement and manufacturing cost reduction. For this reason, there is a need for a conductive ink that can be printed without the process of providing a solvent absorption layer as in Patent Document 1 or the process of roughening a substrate as in Patent Document 2.

  In recent years, high-definition printing of conductive ink is also required. For example, a pattern performance capable of forming a line / space with a width of 100 μm or less (100 μm or less / 100 μm or less) (hereinafter abbreviated as “L / S”) is required in order to cope with higher definition of conductive circuit patterns. It has been. In addition, due to the downsizing of mobile terminals such as mobile phones and game machines, the introduction of touch screen panels, etc., the definition of conductive circuit patterns has been further increased, and a finer L / S (60 μm or less) with a width of 60 μm or less. / 60 μm or less) is also required.

  As a printing method of conductive ink, a lithographic offset printing method as disclosed in Patent Document 4, a screen printing method, and the like are known. Among these, according to the screen printing method, it is possible to ensure a printing pattern having a thickness of several μm or more. On the other hand, according to other methods such as a planographic offset printing method, it is a limit to form a printing pattern having a thickness of about 1 to 2 μm. For this reason, the screen printing method is suitable for realizing a reduction in resistance of a conductive pattern such as a conductive circuit.

  However, as described in Patent Document 4, the screen printing method has a problem that it is not suitable for applications and fields where high-definition printing accuracy is originally required. This is because the screen printing method is a method in which the printing ink is printed on the screen printing plate through the mesh of the opening of the screen printing plate while being filled with the screen printing ink and pressed with a squeegee or the like. That is, the screen printing method is a method of bending and printing the screen printing plate by pressing with a squeegee or the like. For this reason, even if an L / S wiring pattern of, for example, 100 μm or less is formed by the screen printing method, the actual situation is that the line width of the printed material becomes larger than the target line width. As a result, problems such as adjacent wirings approaching or contacting each other and problems such as blurring of edge portions of wirings resulting in unclear borders are caused.

  The reason why such a problem occurs is that the specific gravity of the conductive particles contained in the conductive ink is larger than that of a general printing ink, and the content thereof is extremely large. The conductive ink passes through the opening of the screen plate, and after it is transferred to the base material, it is easy to flow and spread out from the printing area due to the weight of the conductive particles itself, etc., until it is dried and solidified. . Such a problem is particularly noticeable in a high-definition pattern in which the L / S wiring pattern corresponds to 100 μm or less.

  Further, in order to print a high-definition conductive pattern (circuit pattern), it is necessary to use a fine screen mesh. In order to use a fine screen mesh, it is preferable to use conductive particles having a particle size as small as possible. However, the conductive particles having a small particle size are more likely to flow on the movement of the solvent or binder resin contained in the conductive ink being dried and solidified after printing, as compared with those having a large particle size. For this reason, the “thickening” phenomenon of the line width that protrudes outside the printing region is more likely to occur.

  In addition, the items required for the conductive circuit pattern used in touch screen panels that are frequently used in mobile terminals such as mobile phones and game machines in recent years, personal computers, etc., are only high-definition in the horizontal direction described above. In addition, flatness in the thickness direction is also mentioned. There are various types of touch screen panels, and examples include an optical method, an ultrasonic method, a resistive film method, a capacitance method, and a piezoelectric method. Of these, the resistive film method is most often used because of the simplicity of the structure. In the resistive film type touch panel, two transparent conductive substrates on which a transparent conductive film is formed are arranged to face each other with an interval of approximately 10 to 150 μm. In the part touched with a finger, a pen or the like, both transparent electrode substrates come into contact with each other and operate as a switch to select a menu on the display screen, input a handwritten character, and the like.

The structure of the resistive film type touch screen panel will be described in more detail.
For example, a transparent conductive film is provided on a transparent plastic film so that the plastic film is partially exposed by indium oxide doped with tin (hereinafter referred to as ITO), and the conductive film is formed on the plastic film and the transparent conductive film. A conductive circuit (also referred to as a conductive pattern) is formed using ink. And an insulating layer is formed on a conductive circuit, and becomes a transparent conductive substrate. Next, two transparent conductive substrates are bonded together with a double-sided pressure-sensitive adhesive in a state where the transparent conductive films are not directly in contact with each other and are opposed to each other.

However, even if high definition in the horizontal direction is good, if the conductive circuit is uneven in the thickness direction, the convex portion of the conductive circuit may protrude from the insulating layer provided on the conductive circuit. If the convex portion of the conductive circuit protrudes from the insulating layer in the thickness direction, the product performance is likely to deteriorate significantly, such as oxidation of the protruding partial circuit, which directly leads to a decrease in product yield and a high manufacturing cost. In order to avoid the protrusion of the conductive circuit from the insulating layer, there is a method of making the insulating layer sufficiently thick, but it goes against the demand of the age of “thinning”. Accordingly, the conductive circuit is required to have flatness (smoothness) in the thickness direction.
In addition, from the viewpoint of improving productivity, it is required to produce a conductive circuit excellent in high definition in the horizontal direction and flatness in the thickness direction by high-speed printing.

  Furthermore, taking advantage of the characteristics of a plastic film substrate, manufacturing processes such as long web intermediate products and product winding and unwinding may be introduced into touch screen panel manufacturing. The circuit is also required to have flexibility (flexibility).

Further, the touch screen panel is required to have durability under various conditions such as a high temperature environment, a high temperature and high humidity environment, and a heat cycle test.
For example, a vehicle-mounted touch panel used for a car navigation system or the like may be used in a cold region or in extreme heat. A touch panel used for a mobile phone may be used in a high-temperature and high-humidity environment such as a bathroom.
Therefore, the conductive circuit is required to have durability under various conditions, specifically resistance value stability and adhesion maintenance under various conditions. When the polyester resin as disclosed in Patent Documents 10 and 11 is used as the binder resin, the polyester resin is easily hydrolyzed, and the resistance value of the conductive circuit is lowered or the adhesion is deteriorated by various durability tests. To do.
Also, if the plastic film is warped by providing a conductive circuit, it will lead to a decrease in positional accuracy during laminating printing and workability in the subsequent process during assembly. Therefore, it is also desirable that the plastic film does not warp as much as possible even if a conductive circuit is provided.

  The present invention has been made in view of the above-mentioned background, and its object is not a so-called high-temperature firing type, but a low-temperature treatment type conductive ink, and can be applied in a horizontal direction by high-speed screen printing. In addition, it is possible to continuously form a conductive pattern with high definition and flatness in the thickness direction, excellent flexibility, low warpage, and excellent durability, and a special manufacturing process is essential. In addition, the present invention provides a conductive ink excellent in resistance value stability, a laminate with a conductive pattern using the same, and a method for producing the same.

The present invention contains two kinds of conductive particles having different tap densities in a specific ratio, and also uses a specific bisphenol type epoxy resin and an acrylic elastomer as a so-called binder resin in a specific ratio, and further a specific amount of metal The above object was achieved by containing a chelate and a curing agent.
That is, the present invention has a tap density of 4.5 to 7 (g / cm ³ ), a D50 particle diameter of 0.1 to ³ μm of conductive particles (A1), and a tap density of 0.5 to 3. 5 (g / cm ³ ) and D50 particle diameters of 0.1 to ³ μm of conductive particles (A2) in a ratio of 0.25 ≦ [(A1) / (A2)] ≦ 4 (weight ratio) Contained in
A polystyrene-reduced weight average molecular weight (Mw) of 10,000 to 100,000, a bisphenol type epoxy resin (B1) having a hydroxyl value of 2 to 300 (mgKOH / g), a glass transition temperature of −50 to 25 ° C., An acrylic elastomer (B2) having a Mooney viscosity of 10 to 90 in a ratio of 9 ≧ [(B1) / (B2)] ≧ 0.1 (weight ratio);
0.2 to 20 parts by weight of metal chelate (C) is contained with respect to 100 parts by weight of the total of the epoxy resin (B1) and the acrylic elastomer (B2),
A curing agent having a functional group capable of reacting with at least one of a hydroxyl group and an epoxy group of the epoxy resin with respect to a total of 100 parts by weight of the epoxy resin (B1) and the acrylic elastomer (B2) (D 1) to 40 parts by weight,
The present invention relates to a conductive ink in which the total amount of (A1) and (A2) is 55 to 97.5% by weight in 100% by weight of the components excluding the organic solvent.

In the invention, the conductive particles (A1) and (A2) are preferably silver or silver plating powder.
In the invention, the metal chelate (C) is preferably at least one selected from the group consisting of an aluminum chelate, a titanium chelate and a zirconium chelate, and more preferably an aluminum chelate. The aluminum chelate (C) preferably has a group selected from the group consisting of an acetylacetonate group, a methylacetoacetate group and an ethylacetoacetate group.
In the present invention, the curing agent (D) is preferably at least one selected from the group consisting of isocyanate compounds, amine compounds, acid anhydride compounds, mercapto compounds, imidazole compounds, dicyandiamide compounds, and organic acid hydrazide compounds.

  The conductive ink of the invention is preferably for screen printing.

Furthermore, the present invention provides
A base material, and a conductive pattern formed on the base material,
The said conductive pattern is related with the laminated body with a conductive pattern currently formed with the conductive ink in any one of the said invention.

  It is preferable that the laminated body with a conductive pattern of the invention further includes an insulating layer laminated so as to cover the conductive pattern.

Furthermore, the present invention comprises a step of forming a conductive pattern having a desired pattern shape on a substrate by screen printing,
The said conductive pattern is related with the manufacturing method of the laminated body with a conductive pattern using the conductive ink in any one of the said invention.

  With the conductive ink of the present invention, by conducting high-speed screen printing, a conductive pattern that is highly fine in the horizontal direction and flat in the thickness direction, excellent in flexibility, less warped, and excellent in durability is continuously provided. Could be formed.

Conductive particles (A1) and (A2)
As described above, the conductive ink of the present invention contains the conductive particles (A1) and (A2) having different tap densities in a specific ratio.

Conductive particles (A1)
The conductive particles (A1) have a tap density of 4.5 to 7 (g / cm ³ ), preferably 5 to 6.5 (g / cm ³ ).
When the tap density of the conductive particles (A1) is smaller than 4.5 (g / cm ³ ), the conductivity of the obtained ink tends to be lowered, and it becomes difficult to achieve both conductivity and fine printability. On the other hand, when the tap density of the conductive particles (A1) is larger than 7 (g / cm ³ ), the density difference from the conductive particles (A2) described later is too large, and the epoxy resin (A1) and acrylic resin described later are used. It becomes difficult to uniformly disperse in the elastomer (A2), and coarse particles derived from conductive particles remain in the resulting ink, which may adversely affect the viscoelastic behavior and printability.

The conductive particles (A1) have a D50 particle size of 0.1 to 3 μm, preferably 0.2 to 2 μm.
When the D50 particle diameter of the conductive particles (A1) is less than 0.1 μm, the number of contact points between the particles increases, and the influence of contact resistance generated between the particles increases, so that the conductivity of the obtained ink decreases. It becomes easy to do. On the other hand, when it is larger than 3 μm, it is difficult to obtain desired fine printability.

The conductive particles (A1) preferably have a BET specific surface area of 0.1 to 3 (m ² / g), more preferably 0.5 to 2 (m ² / g), and 0.7 More preferably, it is -1.5 (m < ² > / g).
When the BET specific surface area of the conductive particles (A1) is less than 0.1 (m ² / g), the desired hard fine printability is obtained, 3 (m ² / g) is greater than the desired conductivity It is difficult to obtain.

Furthermore, the conductive particles (A1) preferably have an aspect ratio of 1 to 4, and more preferably 1 to 3.5.
As the aspect ratio of the conductive particles in the conductive ink is larger, the particles are more likely to be arranged in the plane direction, so that the conductivity of the formed film tends to be improved. However, when the value is too large, the screen plate is clogged, or even if screen printing can be performed, the shape of the conductive circuit is significantly disturbed. That is, when the aspect ratio of the conductive particles (A1) is larger than 4.0, the fine printability is remarkably deteriorated and it is difficult to use for forming fine wiring by screen printing of the present application.

Conductive particles (A2)
The conductive particles (A2) have a tap density of 0.5 to 3.5 (g / cm ³ ), preferably 1 to 3 (g / cm ³ ).
When the tap density of the conductive particles (A2) is smaller than 0.5 (g / cm ³ ), the density difference from the conductive particles (A1) is too large, and the epoxy resin (A1) and acrylic system described later are used. It becomes difficult to uniformly disperse in the elastomer (A2), and coarse particles derived from conductive particles remain in the resulting ink, which may adversely affect the viscoelastic behavior and printability. On the other hand, when the tap density of the conductive particles (A2) is larger than 3.5 (g / cm ³ ), the fine printability of the obtained ink is lowered, and it is difficult to achieve both conductivity and fine printability.

  Moreover, the D50 particle diameter of electroconductive particle (A2) is 0.1-3 micrometers for the same reason as the case of electroconductive particle (A1), Preferably it is 0.2-2 micrometers.

The conductive particles (A2) preferably have a BET specific surface area of 0.5 to 3.5 (m ² / g), more preferably 0.8 to 3.5 (m ² / g). 1.5 to 3 (m ² / g) is more preferable.
When the BET specific surface area of the conductive particles (A1) is less than 0.5 (m ² / g), the desired hard fine printability is obtained, 3.5 (m ² / g) is greater than the desired conductive It is difficult to obtain sex.

  Furthermore, the aspect ratio of the conductive particles (A2) is preferably 1 to 4 and more preferably 1 to 3.5 for the same reason as in the case of the conductive particles (A1).

  Examples of the conductive particles (A1) and (A2) include gold, silver, copper, silver-plated copper powder, silver-copper composite powder, silver-copper alloy, amorphous copper, nickel, chromium, palladium, rhodium, Metal powder such as ruthenium, indium, silicon, aluminum, tungsten, morphbutene, platinum, inorganic powder coated with these metals, powder of metal oxide such as silver oxide, indium oxide, tin oxide, zinc oxide, ruthenium oxide, Inorganic powders coated with these metal oxides, and carbon black, graphite and the like can be used. These conductive particles (A1) and (A2) may be used alone or in combination of two or more. Among these conductive particles, it is preferable to use silver or silver plating powder for reasons such as conductivity, stability, and a small increase in resistivity due to oxidation.

  The shape of these conductive particles (A1) and (A2) is not particularly limited as long as the above properties are satisfied, and an irregular shape, agglomerated shape, a scale shape, a microcrystalline shape, a spherical shape, a flake shape, and the like are appropriately used. it can. From the viewpoint of the printability of the high-definition pattern and the adhesiveness of the conductor pattern to the substrate, a spherical or small aggregate having a small particle size is preferable as a relatively small aggregate.

Using the conductive particles (A1) and (A2) having different tap densities in a specific ratio is important for ensuring high definition, flatness, and high conductivity during high-speed printing.
That is, in the present invention, the blending ratio [(A1) / (A2)] of the conductive particles (A1) and the conductive particles (B1) is 0.25 ≦ [(A1) / (A2)] ≦ 4. Preferably, 0.33 ≦ [(A1) / (A2)] ≦ 3.
When [(A1) / (A2)] is smaller than 0.25 or only the conductive particles (A2) are used, the conductivity and flatness of the conductive circuit are inferior. On the other hand, if [(A1) / (A2)] is larger than 4 or only the conductive particles (A1) are used, the high definition of the conductive circuit is inferior, and the adhesion is significantly deteriorated by the heat cycle test. To do.

Further, in the conductive ink of the present invention, the content of the conductive particles (A1) and (A2) is important.
The conductive ink of the present invention has a total amount of (A1) and (A2) of 55 to 97.5% by weight and 60 to 95% by weight in a total of 100% by weight of the components excluding the organic solvent. Preferably, it is 80 to 93% by weight. If the conductive particles are less than 55% by weight, the conductivity is not sufficient, and if it exceeds 97.5% by weight, the binder resin that functions as a binder component for the conductive particles decreases, and the conductive ink adheres to the substrate. And the mechanical strength of the coating film may be lowered, which is not preferable.
The “component other than the organic solvent” roughly includes conductive particles (A1) and (A2), bisphenol type epoxy resin (B1), acrylic elastomer (B2), metal chelate (C), and curing described below. It can be called agent (D).

Hereinafter, the tap density, the D50 particle diameter, the BET specific surface area, and the aspect ratio will be described.
<Tap density>
The tap density refers to the weight per volume after a certain amount of powder is placed in a certain container while being shaken up and down. In general, the larger the value, the larger the packing density of the particles, and in the case of conductive particles, the number of contact points between the particles increases, so that good conductivity can be obtained. On the other hand, if the tap density is too high, the influence of contact resistance increases due to excessive contact between particles, the conductivity is lowered, the fluidity as a conductive ink is hindered, or the resistance of the formed conductive circuit is deteriorated. The bendability is deteriorated and cracks are easily generated in the formed conductive circuit.
In addition, the tap density of this invention was measured based on JISZ2512: 2006 method.
Specifically, conductive particles (powder amount 100 g) were collected in a graduated glass container (capacity 100 ml) and tapped with a predetermined touching device under a tap stroke of 3 mm and a tap count of 100 times / minute. .

<D50 particle size>
In the present invention, the D50 particle size of the conductive particles is the cumulative particle size 50% of the volume particle size distribution measured using a laser diffraction particle size distribution measuring device “SALAD-3000” manufactured by Shimadzu Corporation as “D50 particle size”. did.

<BET specific surface area>
BET specific surface area is a value obtained by using low-temperature and low-humidity physical adsorption of inert gas, adsorbing molecules with a known adsorption area on the surface of powder particles at the temperature of liquid nitrogen, and obtaining the specific surface area of the sample from the amount. It is.
In the present invention, the BET specific surface area is described by defining the value calculated by the following calculation formula from the surface area measured using the flow type specific surface area measuring device “Flowsorb II” manufactured by Shimadzu Corporation.
Specific surface area (m ² / g) = surface area (m ² ) / powder mass (g)

<Aspect ratio>
Print an appropriate amount of conductive ink in which conductive particles are dispersed in an arbitrary binder resin on a glass plate, add the amount of heat necessary to complete the drying or curing reaction, and solidify the conductive ink or A cured product was obtained, and the cross section of the cured product was observed with an SEM, and the length in the major axis direction and the length in the minor axis direction of 30 or more randomly selected particles were measured. An average value of 30 or more of values obtained by dividing the length in the major axis direction of each particle by the length in the minor axis direction was determined and used as the aspect ratio.

Binder Resin The conductive ink of the present invention uses a specific bisphenol type epoxy resin (B1) and an acrylic elastomer (B2) in combination at a specific ratio as a so-called binder resin.
By using bisphenol-type epoxy resin (B1) and acrylic elastomer (B2) in a specific amount range, the sagging / thickness of the conductive pattern after the transition and the adhesion to a flexible film substrate such as a polyester film In addition, it is possible to control the mutually contradictory properties of good plate separation, to ensure accurate printability of fine lines and relatively large area portions on the screen plate pattern, and to ensure flatness in the thickness direction. In addition, compared to conductive inks made using other resins such as polyester resin and polyurethane resin, the resistance value is increased by using bisphenol type epoxy resin (B1) and acrylic elastomer (B2) together in a specific amount range. Can form a conductive circuit with low current.

Bisphenol type epoxy resin (B1)
The epoxy resin as used in the present invention refers to diglycidyl ether obtained by condensing bisphenols having two phenolic hydroxyl groups in the molecule and epichlorohydrin to a predetermined molecular weight, or the bisphenols and diglycidyl ether having a predetermined value. An epoxy resin obtained by condensation to molecular weight is shown.

  Examples of bisphenols having two phenolic hydroxyl groups in the molecule include bisphenol A, bisphenol F, bisphenol S, bisphenol AD, biphenol, bisphenol AP, bisphenol C, bisphenol E, bisphenol Z, bisphenol B, bisphenol IBTD, and bisphenol CP. , Bisphenol BA, bisphenol IOTD, bisphenol DED, bisphenol PRD, bisphenol IPTD, bisphenol DEK, bisphenol MZ, bisphenol OT, bisphenol NO, bisphenol DE, bisphenol IPZ, bisphenol DE, bisphenol FL, bisphenol LAD, bisphenol PED, bisphenol DP, bisphenol nBZ, Bisfe Lumpur FBA, bisphenol MPK, bisphenol TCD, bisphenol 3mz, include bisphenol Z4S.

As the bisphenol type epoxy resin (B1), those commercially available as phenoxy resins can be used. For example, JP 07-109331 A, JP 10-77329 A, and JP 11-147930 A can be used. As described in Japanese Patent Laid-Open No. 2006-36801, etc., it is also possible to use a material obtained by appropriately adjusting the type and amount of an alkali catalyst, the type and amount of an organic solvent to be used, the reaction temperature and time, and the like.
Examples of the bisphenol type epoxy resin (B1) used in the present invention include "jER series" manufactured by Mitsubishi Chemical Corporation, "Epototo series" manufactured by Nippon Steel Chemical Co., Ltd., "Phenotote series", and Nagase ChemteX Corporation. “Denacol Series” manufactured by the Company can be used, and these may be used alone or in combination.

The bisphenol type epoxy resin (B1) used in the present invention has an epoxy group and a hydroxyl group, and it is important that the weight average molecular weight (Mw) in terms of polystyrene is 5,000 to 100,000, preferably It is 10,000-80,000, More preferably, it is 30,000-70,000. When the weight average molecular weight of the epoxy resin is smaller than 5,000, even when an appropriate amount of a metal chelate as described later is used, a sufficient storage elastic modulus G ′ for forming fine wiring by screen printing cannot be obtained. If it is greater than 1,000, the solubility in the solvent is extremely deteriorated, or the storage elastic modulus G ′ becomes too high, and screen printing becomes impossible.
The weight average molecular weight in the present invention refers to two resins in series of “LF-604” (GPC column for rapid analysis: 6 mm ID × 150 mm size) manufactured by Showa Denko KK as a gel column using a resin dissolved in THF (tetrahydrofuran). Connected GPC (Gel Permeation Chromatography: Liquid Chromatography for Separating and Quantifying Substances Dissolved in Solvent by Difference in Molecular Size) “HPLC-8020”, Flow Rate 0.6 ml / min, Column It means a value calculated in terms of polystyrene based on data measured at a temperature of 40 ° C.

It is important that the bisphenol type epoxy resin (B1) used in the present invention has a hydroxyl value of 2 to 350 (mgKOH / g), preferably a hydroxyl value of 50 to 300 (mgKOH / g), more preferably 80-250 (mg KOH / g).
Here, the hydroxyl group undergoes an alcohol exchange reaction with the alkoxy group of the metal chelate (C), as will be described later, to impart the necessary rheological properties such as storage elastic modulus G ′ to the printability of the high-definition pattern in the screen printing method. It is necessary as a functional group. Moreover, when using the hardening | curing agent (D) which has a functional group which can react with a hydroxyl group, the excess hydroxyl group of the bisphenol type epoxy resin (B1) after using for reaction with the alkoxide group of a metal chelate is the said hardening | curing agent ( D).
In the present invention, when the hydroxyl value of the bisphenol-type epoxy resin (B1) is smaller than 2 (mgKOH / g), the storage elastic modulus G ′ required for fine drawing formation by the screen printing method can be obtained even when the metal chelate (C) is used. On the other hand, when the hydroxyl value is larger than 350 (mgKOH / g), the storage elastic modulus G ′ becomes too high and screen printing becomes impossible or the Tg of the cured product increases, Problems such as warpage of the coating tend to occur.

The bisphenol type epoxy resin (B1) used in the present invention preferably has an epoxy equivalent (hereinafter also referred to as EPW) of 3,000 to 100,000 (g / eq), and 4,000 to 50,000 ( g / eq) is more preferable.
In the present invention, the epoxy group in the bisphenol-type epoxy resin (B1) is obtained by polymerization by heat, or by reacting directly or indirectly with the curing agent (D) or curing accelerator described later. Contributes to improving physical properties such as mechanical strength and adhesion of the cured coating film of conductive ink.
In the present invention, when the epoxy equivalent of the bisphenol type epoxy resin (B1) is larger than 100,000 (g / eq), the amount of the epoxy group is too small, and the effect of improving the physical properties is not seen.
On the other hand, when the epoxy equivalent is smaller than 3,000 (g / eq), the reaction point increases too much, and the curing shrinkage due to the reaction, the modulus of elasticity, and the Tg increase sharply, and the cured coating film is warped and cracked. Problems such as occurrence are likely to occur.

Moreover, it is preferable that the glass transition temperature (henceforth Tg) is 40-150 degreeC, and, as for the bisphenol type epoxy resin (B1) used for this invention, it is more preferable that it is 50-120 degreeC.
When Tg is lower than 40 ° C., the heat resistance of the cured film of the conductive ink may be deteriorated, and when Tg is higher than 150 ° C., the flexibility of the cured film may be significantly impaired.
The Tg of the bisphenol-type epoxy resin (B1) is a dry resin (powder, droplet, or slice), which is −50 ° C. to 5 ° C./min using a differential calorimeter (DSC). The measurement was performed under the condition of 300 ° C., and the value was determined by the inflection point of the calorimetric curve.

Moreover, when the bisphenol type epoxy resin (B1) used in the present invention is a 40% MEK solution, the viscosity measured at 25 ° C. by the Gardner-Holt method is preferably T to Z10, and V to Z5. It is more preferable that
A 40% MEK solution viscosity lower than T means that the molecular weight of the bisphenol type epoxy resin is small, and even when such a bisphenol type epoxy resin is used, a sufficient storage elastic modulus G ′ can be imparted to the conductive ink. This is not possible and the conductive circuit tends to be fat. On the other hand, the fact that the 40% MEK solution viscosity is higher than Z10 means that the molecular weight of the bisphenol type epoxy resin is large, the storage elastic modulus G ′ becomes too high, and the conductive circuit tends to be distorted.

Acrylic elastomer (B2)
The acrylic elastomer (B2) referred to in the present invention is a rubber-like elastic body obtained by polymerization of an acrylate ester or copolymerization of the acrylic ester, and ethyl acrylate, butyl acrylate, methoxyethyl acrylate, If necessary, a small amount of a reactive monomer having a vinyl group, an epoxy group, a carboxyl group, an amino group, a nitrile group, etc., or a polyfunctional monomer having two or more polymerizable groups in one molecule. Say what is polymerized. Since it is mainly produced by emulsion polymerization, it has a large molecular weight, and unlike a general acrylic resin obtained by ordinary solvent polymerization or bulk polymerization, it exhibits a high storage elastic modulus in a temperature range exceeding Tg.

The acrylic elastomer (B2) used in the present invention preferably has a Tg of −50 to 25 ° C., more preferably −40 to 15 ° C.
When an acrylic elastomer having a Tg lower than −50 ° C. is used, the heat resistance of the formed conductive pattern is remarkably deteriorated, and when a Tg higher than 25 ° C. is used, the bendability of the resulting conductive pattern or after heat treatment is increased. The warpage of the head is significantly worsened.
The Tg of the acrylic elastomer (B2) was determined in the same manner as the bisphenol type epoxy resin (B1).

  The Mooney viscosity of the acrylic elastomer (B2) used in the present invention is 10 to 90 (ML (1 + 4) 100 ° C.), preferably 20 to 60 (ML (1 + 4) 100 ° C.). The Mooney viscosity is a viscosity after 4 minutes have passed after rotating at 100 ° C. for 1 minute and 2 rpm using a Mooney viscometer in accordance with JIS K6300.

When an acrylic elastomer having a Mooney viscosity lower than 10 (ML (1 + 4) 100 ° C.) is used, the fine printability of the resulting conductive ink and the flatness of the printed matter tend to deteriorate, and 90 (ML (1 + 4) 100 ° C. ) Higher, the adhesiveness and bendability of the conductive circuit formed from the resulting conductive ink are likely to deteriorate.
The Mooney viscosity of an acrylic elastomer can be changed by controlling the molecular weight, the degree of crosslinking, and the layer separation state by entanglement and crosslinking between polymers, formation of a layer separation structure, etc. The synthesis can be controlled by synthesis conditions such as synthesis of a molecular weight polymer, copolymerization of monomers having two or more functions, and polymerization of monomers having significantly different Tg of homopolymer.

  Examples of the acrylic elastomer (B2) in the present invention include “Nipol AR series” manufactured by Nippon Zeon Co., Ltd., “AREX series” manufactured by JSR Corporation, “Clarity Series” manufactured by Kuraray Co., Ltd., “Bay manufactured by DuPont Performance Elastomer Co., Ltd.” "Mac series", "EuroPRENE series" manufactured by Polymeri Europa, etc. can be used, and these may be used alone or in combination.

In the present invention, when the bisphenol type epoxy resin (B1) and the acrylic elastomer (B2) are used in combination, the weight ratio [(B1) / (B2)] of both is 9 ≧ [(B1) / (B2)]. It is important that ≧ 0.1, and preferably 4 ≧ [(B1) / (B2)] ≧ 0.4.
When [(B1) / (B2)] is larger than 9, that is, when the bisphenol type epoxy resin (B1) is in a large excess amount, the conductive ink by the combination of the bisphenol type epoxy resin (B1) and the metal chelate (C). Thus, the storage elastic modulus G ′ becomes remarkable, the flexibility of the conductive circuit is deteriorated, and the warp is remarkably increased. When the storage elastic modulus G ′ of the conductive ink is increased, the conductive ink before drying and curing is firmly adhered (bite) to a substrate to be printed such as a plastic film. For this reason, a phenomenon occurs in which the screen plate is strongly attracted to a substrate to be printed such as a plastic film at the time of printing, and the smooth transfer of the conductive ink is prevented, so-called plate separation is poor. When the plate separation is poor, the flatness in the thickness direction is impaired, and the edge portion of the printing portion having a relatively large area is roughened.
On the other hand, when [(B1) / (B2)] is smaller than 0.1, that is, when the amount of the bisphenol-type epoxy resin (B1) is extremely small, not only the resistance value increases but also high-definition printability cannot be ensured. .

Metal chelate (C)
In the present invention, the metal chelate (C) reacts with a hydroxyl group in the bisphenol type epoxy resin (B1) used in the conductive ink, and can impart rheological characteristics necessary for fine printability in the screen printing method. The reaction is considered to be an alcohol exchange reaction with a hydroxyl group in the epoxy resin (B1).
The metal chelate (C) is a chelate compound obtained by reacting a metal alcoside with a chelating agent such as β-diketone or ketoester (such as ethyl acetoacetate), and examples thereof include an aluminum chelate, a zirconium chelate, and a titanium chelate. Aluminum chelate is preferably used because of its availability.

Of the metal chelates (C), the aluminum chelate used in the present invention preferably has a molecular weight of 420 or less, and is preferably an aluminum acetylacetonate complex. An acetylacetonate complex includes an acetylacetonate group: —O—C (CH ₃ ) ═CH—CO (CH ₃ ) and a methyl acetoacetonate group: —O—C (CH ₃ ) ═CH—CO—O—. CH ₃ or an ethyl acetoacetonate group: —O—C (CH ₃ ) ═CH—CO—O—C ₂ H ₅ or the like. The aluminum chelate used in the present invention preferably has 1 to 3 of these groups in one molecule, and has 1 to 3 acetylacetonate groups or 1 to 3 ethylacetoacetate groups. Chelates are more preferred.
Aluminum chelates with a molecular weight greater than 420, aluminum chelates with 4 or more acetylacetonate groups in one molecule, aluminum chelates with 4 or more ethyl acetoacetate groups, and aluminum chelates with long chain alkyl groups There is a risk that wetting with the conductive particles is hindered and the resistivity is increased.
Typical aluminum chelates include ethyl acetoacetate aluminum diisopropionate, aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum tris (acetyl acetate), aluminum monoacetyl acetate bis (ethyl acetoacetate). Acetate), aluminum di-n-butoxide monomethyl acetoacetate, aluminum diisobutoxide monomethyl acetoacetate, aluminum di-sec-butoxide monomethyl acetoacetate and the like.

Of the metal chelates (C), the zirconium chelate used in the present invention preferably has a molecular weight of 350 or more and 1,000 or less. Further, the zirconium chelate is more preferably a zirconium chelate which is an acetylacetonate complex and contains 1 to 4 acetylacetonate groups and 0 to 2 ethylacetoacetate groups in one molecule. Zirconium chelates having a molecular weight of less than 350 may cause the dispersion state of the conductive ink to become unstable and increase the resistivity.
Typical zirconium chelates include zirconium tetraacetylacetonate, zirconium tributoxyacetylacetonate, zirconium monobutoxyacetylacetonate bis (ethylacetoacetate), zirconium dibutoxybis (ethylacetoacetate), zirconium tetraacetylacetate. And the like.

Of the metal chelates (C), the titanium chelate used in the present invention preferably has a molecular weight of 250 to 1,500. Further, titanium chelates and alkoxy titaniums that can be represented by (HOR1O) ₂ Ti (OR2) ₂ or (H ₂ NR1O) ₂ Ti (OR2) ₂ . Here, R1 and R2 are hydrocarbon groups. For example, di-i-propoxybis (acetylacetonato) titanium, di-n-ptoxybis (triethanolaminato) titanium, titanium-i-propoxyoctylene glycolate, titanium stearate, titanium acetylacetonate, titanium tetraacetyl Examples include acetonate, polytitanium acetylacetylacetonate, titanium octylene glycolate, titanium ethyl acetoacetate, titanium lactate, and titanium triethanolamate. Zirconium chelates having a molecular weight of less than 250 may cause the dispersion state of the conductive ink to become unstable and increase the resistivity.

The metal chelate (C) used in the present invention is preferably contained in an amount of 0.2 to 20 parts by weight with respect to a total of 100 parts by weight of the bisphenol type epoxy resin (B1) and the acrylic elastomer (B2). It is more preferable to contain -15 weight part.
If the metal chelate (C) is less than 0.2 parts by weight, the effect of imparting the elastic properties necessary for fine printability in the screen printing method is small, and if it exceeds 20 parts by weight, the elastic properties of the conductive ink are imparted. It becomes too large and screen printing cannot be performed, and the conductivity of the ink may be deteriorated.

Until now, the general idea that the printing accuracy in the screen printing method can be improved by controlling the viscosity and the thixotropy, and the thixotropy has been evaluated by the TI value (thixo index, TI value).
However, it is not sufficient to grasp and evaluate the behavior during printing of printing inks that have a property (viscoelasticity) that has both fluidity (viscous flow) and elastic properties (elastic deformation) by viscosity and TI value. It was.
Therefore, in the present invention, by using a specific amount of the metal chelate (C) for the bisphenol type epoxy resin (B1) and the acrylic elastomer (B2), the viscosity property (viscosity) is not greatly affected. The elastic property (storage modulus G ′) was controlled to enable high-definition printing.

The conductive ink of the present invention has an elastic property that the storage elastic modulus G ′ is 1,000 to 50,000 (Pa) at 25 ° C., frequency 1 (Hz), vibration stress 50 (Pa), Further, a value obtained by dividing the loss elastic modulus G ″ by the storage elastic modulus G ′, tan δ, is preferably 1 or less in order to impart printability of a high-definition pattern.
When the storage elastic modulus G ′ at 25 ° C., frequency 1 (Hz), and vibration stress 50 (Pa) is less than 1,000 Pa, the elasticity is weak, and the ink passes through the opening of the screen and is transferred to the substrate. It becomes difficult to maintain the shape of the pattern, pattern thickening and meandering occur, and the printability of a high-definition pattern is poor.
On the other hand, when the storage elastic modulus G ′ of the conductive ink exceeds 50,000 Pa, the elasticity becomes too strong, the ink cannot be rolled on the screen printing plate, and it is difficult to fill a predetermined pattern provided on the screen. For this reason, pattern blurring or chipping occurs, and screen printing cannot be performed.
The storage elastic modulus G ′ is preferably 1,000 to 25,000, and more preferably 6,000 to 10,000.
On the other hand, when tan δ of the conductive ink exceeds 1, the elastic properties are reduced, pattern thickening and meandering are likely to occur, and high-definition pattern printability tends to be inferior.
There are various methods for evaluating the viscoelastic behavior of conductive ink, but the measurement method with fixed sine vibration frequency and changing vibration stress measures the dynamic viscoelasticity of dispersed systems such as conductive ink. Is preferred.

Curing agent (D)
By containing the hardening | curing agent (D), the electroconductive ink of this invention can further suppress the heat resistance of the film after hardening, the resistance value in a high-temperature, high-humidity environment, and adhesive deterioration.
As this hardening | curing agent (D), what can react with an epoxy group and a hydroxyl group is used, and what reacts with an epoxy group is preferable. Examples of the curing agent include isocyanate compounds, amine compounds, acid anhydride compounds, mercapto compounds, imidazole compounds, dicyandiamide compounds, organic acid hydrazide compounds, and the like.
For example, when making it react with the hydroxyl group of an epoxy resin, an isocyanate compound can be used as a hardening | curing agent.
When making it react with the epoxy group of an epoxy resin, an amine compound, an acid anhydride compound, a mercapto compound, an imidazole compound, a dicyandiamide compound, and an organic acid hydrazide compound can be used as a curing agent.

Examples of the isocyanate compound that can be used as the curing agent (D) include non-blocked isocyanate and blocked isocyanate.
As the isocyanate compound, a polyisocyanate compound is preferable. As the polyisocyanate compound, conventionally known aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate, or blocked isocyanate which is a block body thereof can be used, and these are used alone or in combination of two or more. May be. Examples of aromatic polyisocyanates include trimethylolpropane adducts of tolylene diisocyanate, isocyanurates of tolylene diisocyanate, oligomers of 4,4′-diphenylmethane diisocyanate, and the like.
Examples of the aliphatic polyisocyanates include biurets of hexamethylene diisocyanate, isocyanurates of hexamethylene diisocyanate, uretdiones of hexamethylene diisocyanate, and isocyanurates of copolymers composed of tolylene diisocyanate and hexamethylene diisocyanate. Examples of the alicyclic polyisocyanate include isocyanurates of isophorone diisocyanate. As the blocked isocyanate, a conventionally known one in which polyisocyanate is blocked with ε-caprolactam, butanone oxime, phenol, active methylene compound or the like can be used.

  Examples of the amine compound in the curing agent (D) used in the conductive ink of the present invention include aliphatic amines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, and diethylaminopropylamine, and N-aminoethyl. Examples thereof include alicyclic amines such as piperazine, mensendiamine, isophoronediamine, hydrogenated m-xylenediamine, and aromatic amines such as m-xylylenediamine, m-phenylenediamine, diaminodiphenylmethane, and diaminodiphenylsorbone. Further, amine adducts and ketimines modified with these amines, polyamide resins having a reactive primary amine and secondary amine in the molecule, produced by condensation of dimer acid and polyamine, and the like are also included.

  Of the curing agent (D) used in the conductive ink of the present invention, examples of the acid anhydride compound include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, Glycerol trislimitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydro Phthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic acid anhydride, alkylstyrene-maleic anhydride copolymer, chlorendic anhydride, polyazeline acid anhydride, none And methyl nadic acid.

  Among the curing agents (D) used in the conductive ink of the present invention, examples of the mercapto compound include liquid polymercaptan and polysulfide resin.

  Among the curing agents (D) used in the conductive ink of the present invention, as imidazole compounds, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, Examples include latent curing agents with improved storage stability such as imidazole compounds such as 2-phenylimidazole, and types in which these imidazole compounds and epoxy resins are reacted to insolubilize them, or types in which imidazole compounds are encapsulated in microcapsules. It is done.

  Of the curing agent (D) used in the conductive ink of the present invention, examples of the dicyandiamide compound include dicyandiamide (DICY).

  In this invention, as a hardening | curing agent (D) to be used, an imidazole compound and a dicyandiamide compound are more preferable from a viewpoint of the reactivity and the tolerance of the coating film after hardening. Moreover, these hardening | curing agents may be used independently and may use multiple together.

The conductive ink of the present invention preferably contains 1.0 to 40 parts by weight of the curing agent (D) with respect to 100 parts by weight in total of the epoxy resin (B1) and the acrylic elastomer (B2). 10 to 30 parts by weight is more preferable.
When the curing agent (D) is less than 1.0 part by weight, sufficient adhesion and heat resistance cannot be imparted to the printed matter, and when it exceeds 40 parts by weight, the unreacted curing agent becomes conductive ink. It tends to remain, and it is difficult to provide sufficient adhesion and heat resistance.

The conductive ink of the present invention may contain a curing accelerator that accelerates the thermal curing of the curing agent.
As such a curing accelerator, an organic tin compound, an amine compound, or the like can be used in the reaction between the hydroxyl group of the epoxy resin and the isocyanate compound. Examples of organotin compounds include stannous octaate (SO) and dibutyltin dilaurate (DBTDL). Examples of the amine compound include diazabicyclooctane (DABCO), N-ethylmorpholine (NEM), triethylamine (TEA), N, N, N ′, N ″, N ″ -pentamethyldiethyltriamine (PMDETA) and the like. It is done.

  Further, as a curing accelerator in the reaction between the epoxy group of the epoxy resin and the curing agent described above, dialkyl such as dicyandiamide, tertiary amine compound, phosphine compound, imidazole compound, carboxylic acid hydrazide, aliphatic or aromatic dimethylurea. Examples include ureas. Examples of the tertiary amine compound include triethylamine, benzyldimethylamine, 1,8-diazabicyclo (5.4.0) undecene-7, 1,5-diazabicyclo (4.3.0) nonene-5, and the like. . Examples of the phosphine compound include triphenylphosphine and tributylphosphine. As a midazole compound, the imidazole compound mentioned by the above-mentioned hardening | curing agent can be mentioned. For example, imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, etc., and reacting these imidazole compounds with epoxy resins A latent curing accelerator with improved storage stability, such as a type insolubilized in a solvent or a type in which an imidazole compound is encapsulated in a microcapsule, can be mentioned. Examples of the carboxylic acid hydrazide include succinic acid hydrazide and adipic acid hydrazide.

The conductive ink of the present invention can be dissolved and diluted with various solvents, and is preferably used in a range of 50 to 90% by weight as a solid content.
When the solid content is lower than 50%, it is difficult to obtain the storage elastic modulus necessary for fine wiring drawing by the screen printing method. On the other hand, when the solid content is higher than 90%, drawing defects such as blurring and disconnection at the time of printing are not obtained. Cause.
The solvent for dilution can be selected according to the solubility of the resin used and the type of printing method.
For example, an ester solvent, a ketone solvent, a glycol ether solvent, an aliphatic solvent, an alicyclic solvent, an aromatic solvent, an alcohol solvent, water or the like may be used in combination. However, it is not limited to these.
Examples of the ester solvent include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, and dimethyl carbonate.
Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone benzene, diisobutyl ketone, diacetone alcohol, isophorone, and cyclohexanenone.
Examples of glycol ether solvents include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, etc., acetates of these monoethers, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene Examples include glycol monomethyl ether, propylene glycol monoethyl ether, and the like, and acetates of these mono ethers.
Examples of the aliphatic solvent include n-heptane, n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane.
Examples of the aromatic solvent include toluene, xylene, tetralin and the like.

  In addition, the conductive ink of the present invention includes a dispersant, an antifriction agent, an infrared absorber, an ultraviolet absorber, a fragrance, an antioxidant, an organic pigment, an inorganic pigment, an antifoaming agent, and a silane coupling as necessary. An agent, a plasticizer, a flame retardant, a humectant, and the like can be added.

The conductive ink of the present invention comprises conductive particles, bisphenol-type epoxy resin, acrylic elastomer, metal chelate, curing agent, solvent and the like mixed in a desired ratio and mixed with a disper etc. It can be obtained by mixing and dispersing with a roll or the like. After blending all the ingredients, they can be mixed or mixed and dispersed to obtain a conductive ink. After mixing or mixing and dispersing several ingredients, each component has a desired ratio. It can also be mixed to obtain a conductive ink.
For example, after mixing or mixing and dispersing two kinds of conductive particles, bisphenol type epoxy resin, acrylic elastomer, metal chelate, solvent and the like, a curing agent is added to obtain a conductive ink.
Alternatively, after obtaining a resin solution containing at least one of a bisphenol-type epoxy resin or an acrylic elastomer and a solvent, two types of conductive particles are separately dispersed in the resin solution, and then two types of conductive particles are obtained. The active particle dispersion can also be mixed. When two kinds of conductive particles are dispersed separately, the metal chelate and the curing agent can be blended at the time of each dispersion, or can be blended at the time of one dispersion. It can also mix | blend when mixing an electroconductive particle dispersion, and can also mix | blend after mixing two types of electroconductive particle dispersions.
In the conductive ink of the present invention, after obtaining a resin solution containing a bisphenol type epoxy resin and an acrylic elastomer, a curing agent and a solvent, two kinds of conductive particles are separately dispersed in the resin solution, and then It is preferable to obtain by mixing a mixture of metal chelates and then mixing two types of conductive particle dispersions. Conductive ink obtained by dispersing two types of conductive particles separately is thicker and finer than other methods, for example, conductive ink obtained by mixing and dispersing all components at once. It is possible to form a conductive pattern having a smaller height difference, that is, a sharp, thin and flat conductive pattern.

The conductive ink of the present invention can be applied to various conventionally known printing methods, and is particularly preferably applied to screen printing.
In the screen printing method, as described above, it is preferable to use a fine mesh screen, particularly preferably a fine mesh screen of about 400 to 840 mesh, in order to cope with high definition of the conductive circuit pattern. At this time, the open area of the screen is preferably about 20 to 70%. The screen wire diameter is preferably about 5 to 70 μm.
Examples of the screen plate include polyester screens, stainless mesh screens, combination screens, metal screens, and nylon screens. Moreover, when printing the thing of a highly viscous paste state, a high tension | tensile_strength stainless steel screen or a high tension | tensile_strength combination screen can be used.
The screen printing squeegee may be round, rectangular or square, and an abrasive squeegee can be used to reduce the attack angle (angle between printing plate and squeegee). Other printing conditions may be conventionally known conditions, but it is preferable to set optimum conditions according to the characteristics of the screen and squeegee.

By using the conductive ink of the present invention and printing on a substrate by various printing methods, a high-definition conductive circuit pattern can be formed.
Further, the base film is not particularly limited. For example, polyethylene terephthalate film, polyethylene naphthalate film, polyparaphenylene terephthalamide film, polyether nitrile film, polyether sulfone film, polyvinyl chloride film, acrylic resin film , Polycarbonate film, and the like.
In addition, a conductive material such as ITO is formed on glass by sputtering, wet coating, etc. on a polymer film such as polyethylene terephthalate, polyethylene naphthalate polyester film, polycarbonate, polyethersulfone, acrylic resin, etc. Conductive glass and the like. In addition, ceramics, glass substrates and the like can be used. In particular, in a touch screen panel, a conductive film such as an ITO film having a conductive layer formed on a polyester film and a conductive glass such as ITO glass having a conductive layer formed on glass are often used.

  The conductive circuit pattern printed on the substrate is heated to dry and solidify, and when a curing agent is added to the conductive ink, it is cured. The heating temperature is preferably 80 to 230 ° C., and the heating time is preferably 10 to 120 minutes.

If necessary, for the purpose of further improving the printability of the high-definition pattern wiring, an anchor coat layer can be provided on the substrate, and further conductive ink can be printed on the anchor coat layer.
Such an anchor coat layer is not particularly limited as long as it has good adhesion to the substrate and further good adhesion of the conductive ink, and also requires organic fillers such as resin beads and inorganic fillers such as metal oxides. Can be added accordingly. The method of providing these anchor coat layers is not particularly limited, and can be obtained by applying, drying and curing by a conventionally known coating method.

  Hereinafter, the present invention will be specifically described by way of examples. In the examples, “parts” and “%” mean “parts by weight” and “% by weight”, respectively, the hydroxyl value means KOH mg / g, and the epoxy equivalent means g / eq.

[Silver powder 1]
A spherical silver powder (tap density 5.2 g / cm ³ , D50 particle diameter 0.9 μm, aspect ratio 1.2, specific surface area 0.94 m ² / g) manufactured by DOWA Electronics Co., Ltd. was used as silver powder A.

[Silver powder 2]
Spherical silver powder (tap density 5.1 g / cm ³ , D50 particle size 1.4 μm, aspect ratio 1.1, specific surface area 1.50 m ² / g) manufactured by Fukuda Metal Co., Ltd. was used as silver powder B.

[Silver powder 3]
Spherical silver powder (tap density 4.2 g / cm ³ , D50 particle size 1.3 μm, aspect ratio 1.3, specific surface area 0.93 m ² / g) manufactured by Fukuda Metal Co., Ltd. was used as silver powder C.

[Silver powder 4]
Metal powder Flake silver powder (tap density 5.3 g / cm ³ , D50 particle diameter 6.8 μm, aspect ratio 2.5, specific surface area 0.29 m ² / g) was defined as silver powder D.

[Silver powder 5]
Flake silver powder (tap density 3.7 g / cm ³ , D50 particle size 4.9 μm, aspect ratio 3.5, specific surface area 4.50 m ² / g) manufactured by SINO-PLATINUM was used as silver powder B.

[Silver powder 6]
Metal powder Flake silver powder (tap density 2.8 g / cm ³ , D50 particle diameter 1.2 μm, aspect ratio 1.2, specific surface area 1.50 m ² / g) was defined as silver powder F.

[Silver powder 7]
Spherical silver powder (tap density: 3.2 g / cm ³ , D50 particle size: 0.9 μm, aspect ratio: 1.3, specific surface area: 3.00 m ² / g) manufactured by Johnson Matthey was used as silver powder G.

[Silver powder 8]
A spherical silver powder (tap density 3.7 g / cm ³ , D50 particle diameter 0.9 μm, aspect ratio 1.2, specific surface area 1.33 m ² / g) manufactured by DOWA Electronics Co., Ltd. was used as silver powder H.

[Silver powder 9]
Spherical silver powder (tap density 0.9 g / cm ³ , D50 particle diameter 5.1 μm, aspect ratio 1.4, specific surface area 1.91 m ² / g) manufactured by Mitsui Kinzoku Co., Ltd. was used as silver powder I.

[Silver powder 10]
A foil-like silver powder (tap density 1.1 g / cm ³ , D50 particle diameter 8.9 μm, aspect ratio 22.0, specific surface area 2.14 m ² / g) manufactured by DOWA Electronics Co., Ltd. was defined as silver powder J.

[Silver powder 11]
Flake silver powder (tap density 2.9 g / cm ³ , D50 particle diameter 5.2 μm, aspect ratio 2.8, specific surface area 5.60 m ² / g) manufactured by SINO-PLATINUM was used as silver powder K.

<Measurement of tap density, D50 particle diameter, aspect ratio and BET specific surface area of silver powder>
1) Tap density It measured based on JIS Z 2512: 2006 method.
2) D50 particle size The cumulative particle size (D50) of the volume particle size distribution measured using a laser diffraction particle size distribution measuring device “SALAD-3000” manufactured by Shimadzu Corporation was measured.
3) Aspect ratio A conductive ink for measuring an aspect ratio obtained by adding each conductive particle and a curing agent (1) to a binder resin (1), which will be described later, is prepared, and a sample of a cured product of the conductive ink is prepared. The sample was cut with the apparatus of 1 to expose the cross section. The cross section was observed by SEM, and the length in the major axis direction and the length in the minor axis direction of 30 or more randomly selected particles were measured. An average value of 30 or more of values obtained by dividing the length in the major axis direction of each particle by the length in the minor axis direction was determined and used as the aspect ratio.
4) BET specific surface area The specific surface area was calculated | required based on the following formula from the value of the surface area measured using the flow type specific surface area measuring apparatus "Flowsorb II" by Shimadzu Corporation.
Specific surface area (m ² / g) = surface area (m ² ) / powder mass (g)

(Binder 1)
40 parts by Mitsubishi Chemical Corporation, jER1256 (phenoxy resin comprising bisphenol A skeleton, weight average molecular weight 51,000, epoxy equivalent 7,800, hydroxyl value 200, Tg 95 ° C.), 30 parts γ-butyrolactone and ethyl carbitol acetate 30 To a binder (1) solution having a nonvolatile content of 40%.

(Binder 2)
40 parts of Mitsubishi Chemical Co., Ltd., jER4250 (phenoxy resin comprising bisphenol A and bisphenol F skeleton, weight average molecular weight 59,000, epoxy equivalent 8,200, hydroxyl value 210, Tg 70 ° C.), 30 parts of γ-butyrolactone and ethylcarby It was dissolved in a mixed solvent with 30 parts of tall acetate to obtain a binder (2) solution having a nonvolatile content of 40%.

(Binder 3)
40 parts by Mitsubishi Chemical Corporation, jER1009 (weight average molecular weight 4,000, epoxy equivalent 2,800, hydroxyl value 196, Tg 144 ° C.) are dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate. A binder (3) solution having a nonvolatile content of 40% was obtained.

(Binder 4)
A reactor equipped with a stirrer, a thermometer, a rectifying tube, a nitrogen gas introduction tube, and a pressure reducing device was added to jER4250 (phenoxy resin comprising bisphenol A and bisphenol F skeleton, weight average molecular weight 59,000, epoxy equivalent 8,200, hydroxyl group No. 210, Tg 70 ° C.) 40 parts, phenyl isocyanate 17.8 parts, dibutyltin laurate 0.06 parts, γ-butyrolactone 43.4 parts, ethyl carbitol acetate 43.4 parts, and gradually heated to 120 ° C. The urethanization reaction was performed. After confirming that the isocyanate absorption peak disappeared by IR, cooling. A binder (4) solution was obtained by adjusting with a mixed solvent of γ-butyrolactone / ethyl carbitol acetate = 50/50 so that the nonvolatile content was 40%.
The resin in the obtained solution had a weight average molecular weight of 65,000, an epoxy equivalent of 9,000, a hydroxyl value of 1, and a Tg of 60 ° C.

(Binder 5)
In a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction pipe, dicyclopentadiene diepoxide and bisphenol A are mixed with phenolic bisphenol A with respect to 1 mol of epoxy group in dicyclopentadiene diepoxide. The mixture was charged so that the hydroxyl group was 0.96 mol, and a mixed solvent of γ-butyrolactone / ethyl carbitol acetate = 50/50 was added so that triphenylphosphine was 1% and nonvolatile content was 40% as a catalyst. While gradually raising the temperature to 150 ° C., a high Tg epoxy resin was synthesized.
Confirmed that the absorption peak intensity of the epoxy group has converged by IR, then cooled. A binder (5) solution was obtained by adjusting with a mixed solvent of γ-butyrolactone / ethyl carbitol acetate = 50/50 so that the nonvolatile content was 40%.
The resin in the obtained solution had a weight average molecular weight of 15,000, an epoxy equivalent of 12,000, a hydroxyl value of 175, and a Tg of 160 ° C.

(Binder 6)
In a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 1,6-hexane diepoxide and bisphenol A are added to bisphenol per 1 mol of epoxy group in 1,6-hexane diepoxide. A mixed solvent of γ-butyrolactone / ethyl carbitol acetate = 50/50 so that the phenolic hydroxyl group of A is 0.96 mol, triphenylphosphine is 1% and nonvolatile content is 40% as a catalyst. The Tg epoxy resin was synthesized while gradually raising the temperature to 150 ° C.
Confirmed that the absorption peak intensity of the epoxy group has converged by IR, then cooled. A binder (6) solution was obtained by adjusting with a mixed solvent of γ-butyrolactone / ethyl carbitol acetate = 50/50 so that the nonvolatile content was 40%.
The resin in the obtained solution had a weight average molecular weight of 18,000, an epoxy equivalent of 6,500, a hydroxyl value of 230, and a Tg of 30 ° C.

(Binder 7) Synthesis of polyester resin A reactor equipped with a stirrer, a thermometer, a rectifying tube, a nitrogen gas introduction tube, and a decompression device, 20.3 parts of dimethyl terephthalate, 20.3 parts of dimethyl isophthalate, ethylene glycol 9 parts, 18.2 parts of neopentyl glycol, and 0.03 part of tetrabutyl titanate were charged, gradually heated to 180 ° C. while stirring under a nitrogen stream, and subjected to a transesterification reaction at 180 ° C. for 3 hours. Subsequently, 28.3 parts of sebacic acid was charged and gradually heated to 180 to 240 ° C. to carry out an esterification reaction. The reaction was carried out at 240 ° C. for 2 hours, the acid value was measured, and when it became 15 or less, the reaction vessel was gradually depressurized to 1 to 2 torr, and when the predetermined viscosity was reached, the reaction was stopped and taken out. A polyester resin having 52,900, a number average molecular weight of 23,000, a hydroxyl value of 5, and an acid value of 1 was obtained. 40 parts of the polyester resin was dissolved in 60 parts of isophorone to obtain a binder (7) solution having a nonvolatile content of 40%.

(Binder 8) Synthesis of polyurethane resin Polyester polyol obtained from isophthalic acid and 3-methyl-1,5-pentanediol in a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube (Corporation) Kuraray "Kuraray polyol P-2030", Mn = 2033) 127.4 parts, dimethylolbutanoic acid 4.2 parts, isophorone diisocyanate 19.2 parts, and diethylene glycol monoethyl ether acetate 32.5 parts, nitrogen stream The reaction is carried out at 90 ° C. for 3 hours, and then 115 parts of diethylene glycol monoethyl ether acetate is added. A polyurethane having a weight average molecular weight of 48,600, a number average molecular weight of 18,000, a hydroxyl value of 4, and an acid value of 10 A resin solution was obtained. 26 parts of isophorone was added to 100 parts of a polyurethane resin solution to obtain a binder (8) solution having a nonvolatile content of 40%.

(Binder 9)
40 parts of Nipol AR51 (Tg-14 ° C., Mooney viscosity 55) manufactured by Nippon Zeon Co., Ltd. is dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate, and a binder having a nonvolatile content of 40% (7 ) A solution was obtained.

(Binder 10)
40 parts of Nipol AR53L (Tg-32 ° C., Mooney viscosity 34), manufactured by Nippon Zeon Co., Ltd., is dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate to give a binder (8 ) A solution was obtained.

(Binder 11)
40 parts of Nipol AR12 (Tg-28 ° C., Mooney viscosity 33) manufactured by Nippon Zeon Co., Ltd. is dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate, and a binder having a nonvolatile content of 40% (9 ) A solution was obtained.

(Binder 12)
85 parts of butyl methacrylate (BMA), 15 parts of methyl methacrylate (MMA), and 2 parts of “Aqualon KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. are dissolved in 32 parts of ion-exchanged water as an ammonia neutralizing anionic surfactant. The obtained emulsion was added to the dropping tank and stirred.
In a reactor equipped with a stirrer, thermometer, rectifying tube, nitrogen gas introduction tube, decompression device, and dropping tank, 75 parts of ion-exchanged water and 0.2 part of “RA-9607” manufactured by Nippon Emulsifier Co., Ltd. were charged. The inside of the reaction vessel was replaced with nitrogen gas, the liquid temperature was raised to 80 ° C. while stirring, and 0.1 part of a 3% potassium sulfate aqueous solution was added as a solid content.
After 5 minutes, dropping of the emulsion was started from the dropping tank, and in parallel with this, 0.35 part of 3% potassium persulfate aqueous solution was added dropwise from another dropping port over 3 hours.
While maintaining the liquid temperature at 80 ° C., 60 minutes after the completion of the dropwise addition of the emulsion, 1% t-butyl hydroperoxide aqueous solution and 1% Rongalite aqueous solution are used as solids and 0.02 parts are divided into three portions every 30 minutes. The mixture was further aged at 80 ° C. for 60 minutes with stirring, and then cooled to obtain a BMA / MMA copolymer emulsion.
From this emulsion, residual additives such as surfactants were washed with ethanol and water, and then the water was evaporated to dryness to obtain an acrylic resin dry solid having a solid content of 100%.
The obtained acrylic resin dried product had a Tg of 30 ° C. and a Mooney viscosity of 85.
40 parts of this dried acrylic resin was dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate to obtain a binder (10) solution having a nonvolatile content of 40%.

(Binder 13)
100 parts of 2-ethylhexyl acrylate (2EHA) and 2 parts of "Aqualon KH-10" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. dissolved in 32 parts of ion-exchanged water as an ammonia-neutralized anionic surfactant were added and stirred. Then, the obtained emulsion was charged in a dropping tank.
In a reactor equipped with a stirrer, thermometer, rectifying tube, nitrogen gas introduction tube, decompression device, and dropping tank, 75 parts of ion-exchanged water and 0.2 part of “RA-9607” manufactured by Nippon Emulsifier Co., Ltd. were charged. The inside of the reaction vessel was replaced with nitrogen gas, the liquid temperature was raised to 80 ° C. while stirring, and 0.1 part of a 3% potassium sulfate aqueous solution was added as a solid content.
After 5 minutes, dropping of the emulsion was started from the dropping tank, and in parallel with this, 0.35 part of 3% potassium persulfate aqueous solution was added dropwise from another dropping port over 3 hours.
While maintaining the liquid temperature at 80 ° C., 60 minutes after the completion of the dropwise addition of the emulsion, 1% t-butyl hydroperoxide aqueous solution and 1% Rongalite aqueous solution are used as solids and 0.02 parts are divided into three portions every 30 minutes. The mixture was further aged at 80 ° C. for 60 minutes with stirring, and then cooled to obtain a BMA / MMA copolymer emulsion.
From this emulsion, residual additives such as surfactants were washed with ethanol and water, and then the water was evaporated to dryness to obtain an acrylic resin dry solid having a solid content of 100%.
The obtained acrylic resin dried product had a Tg of −55 ° C. and a Mooney viscosity of 19.
40 parts of this acrylic resin dried product was dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate to obtain a binder (11) solution having a nonvolatile content of 40%.

(Binder 14)
A reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube, and dropping tank was charged with 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate, and 4 parts of butyl acrylate in a dropping tank equipped with a stirrer. Then, 36 parts of ethyl acrylate and 0.8 part of azobisisobutyronitrile (AIBN) were charged, the temperature was raised to 100 ° C. while introducing nitrogen into the reaction apparatus, and stirring of the dropping tank was started.
After the dropping tank is uniformly dissolved and the reaction tank reaches 100 ° C., the solution in the dropping tank is gradually dropped over 2 hours. After the dropping is completed, 0.2 part of AIBN is added 4 times every 30 minutes. It was put into the reaction tank. After the completion of the addition, the mixture was stirred at 100 ° C. for 1.5 hours and cooled to obtain a binder (12) solution having a nonvolatile content of 40%.
The resin in the obtained solution had a weight average molecular weight of 25,000, Tg-23 ° C., and Mooney viscosity of 3.

(Binder 15)
10 parts butyl acrylate (BA), 90 parts ethyl acrylate (EA), 2 parts 1,6-hexanediacrylate, “Aqualon KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as an ammonia neutralizing anionic surfactant A solution obtained by dissolving 2 parts in 32 parts of ion-exchanged water was added and stirred, and the resulting emulsion was charged into a dropping tank.
In a reactor equipped with a stirrer, thermometer, rectifying tube, nitrogen gas introduction tube, decompression device, and dropping tank, 75 parts of ion-exchanged water and 0.2 part of “RA-9607” manufactured by Nippon Emulsifier Co., Ltd. were charged. The inside of the reaction vessel was replaced with nitrogen gas, the liquid temperature was raised to 80 ° C. while stirring, and 0.1 part of a 3% potassium sulfate aqueous solution was added as a solid content.
After 5 minutes, dropping of the emulsion was started from the dropping tank, and in parallel with this, 0.35 part of 3% potassium persulfate aqueous solution was added dropwise from another dropping port over 3 hours.
While maintaining the liquid temperature at 80 ° C., 60 minutes after the completion of the dropwise addition of the emulsion, 1% t-butyl hydroperoxide aqueous solution and 1% Rongalite aqueous solution are used as solids and 0.02 parts are divided into three portions every 30 minutes. The mixture was further aged at 80 ° C. for 60 minutes with stirring, and then cooled to obtain a BMA / MMA copolymer emulsion.
From this emulsion, residual additives such as surfactants were washed with ethanol and water, and then the water was evaporated to dryness to obtain an acrylic resin dry solid having a solid content of 100%.
The obtained acrylic resin dried product had a Tg of -18 ° C and a Mooney viscosity of 100.
40 parts of this acrylic resin dried product was dissolved in a mixed solvent of 30 parts of γ-butyrolactone and 30 parts of ethyl carbitol acetate to obtain a binder (13) solution having a nonvolatile content of 40%.

<Mw, Tg, hydroxyl value, epoxy equivalent, Mooney viscosity of each binder>
1) Mw
Tosoh Corporation GPC (Gel Permeation Chromatography) “HPC-8020” in which two columns “LF-604” (Showa Denko KK: GPC column for rapid analysis: 6 mm ID × 150 mm size) were connected in series. The weight average molecular weight (Mw) was determined in terms of polystyrene using a solvent (THF; tetrahydrofuran), a flow rate of 0.6 ml / min, and a column temperature of 40 ° C.
2) Tg
Using “DSC220C” manufactured by SII NanoTechnology Co., Ltd., the temperature was measured at −50 ° C. to 300 ° C. at a rate of temperature increase of 5 ° C./min.
3) Hydroxyl value: Measured according to JIS K 0070.
4) Epoxy equivalent It measured according to JISK7236.
5) Mooney Viscosity Using a Mooney viscometer “SMV-300” manufactured by Shimadzu Corporation according to JIS K6300, preheating was performed at 100 ° C. for 1 minute and at 2 rpm, and the viscosity after 4 minutes was measured.

[Metal chelate A1]
As an aluminum chelate, ALCH (general formula (1), solid content 90%) manufactured by Kawaken Fine Chemical Co., Ltd. was adjusted to a solid content of 45% using butyl carbitol acetate, and a solution of metal chelate A1 and did.

General formula (1)

[Metal chelate A2]
As a titanium chelate, Matsugai Fine Chemical Co., Ltd. Olga Chics TC-100 (titanium acetylacetonate, solid content 75%) was adjusted using butyl carbitol acetate so that the solid content would be 45%. It was set as the solution.

[Metal chelate A3]
As a zirconium chelate, ORGATIZ ZC-540 (zirconium tributoxy monoacetylacetonate, solid content 45%) manufactured by Matsumoto Fine Chemical Co., Ltd. was used as the metal chelate A3 solution.

[Curing agent 1]
An imidazole type curing agent, Adeka Hardener EH-4346S (manufactured by Adeka Co., Ltd., solid content 100%) was used as a curing agent (1).
[Curing agent 2]
A block type hexamethylene diisocyanate curing agent, Duranate MF-K60X (manufactured by Asahi Kasei Chemicals Corporation, solid content 60%) was used as a solution of the curing agent (2).
[Curing agent 3]
Dicyandiamide (solid 100%) was used as the curing agent (3).

Example 1 <Preparation of conductive ink>
1: 39.1 parts by weight of silver powder as conductive particles (A1);
Silver powder 6: 39.1 parts by weight as conductive particles (A2),
Binder (1) solution containing 4.32 parts by weight of epoxy resin: 10.8 parts by weight;
Binder (7) solution containing 2.2 parts by weight of acrylic elastomer: 5.5 parts by weight;
A solution of metal chelate C1 containing 0.54 parts by weight of aluminum ethyl acetoacetate diisopropionate: 1.2 parts by weight;
Curing agent (1): 1.7 parts by weight,
a mixed solvent of 1/1 (weight ratio) of γ-butyrolactone and ethyl carbitol acetate: 2.3 parts by weight;
Butyl carbitol acetate: 0.4 part by weight was mixed with a disper and dispersed with three rolls to prepare a conductive ink.
The obtained conductive ink has a solid content (a component excluding an organic solvent) of about 87% by weight. The total amount of silver powder 1 and silver powder 6 in about 87 parts by weight of solids is about 78.2 parts by weight, which corresponds to about 90% by weight in 100% by weight of solids. The weight ratio of the conductive particles (A1) to the conductive particles (A2) is [(A1) / (A2)] = about 1. The weight ratio of the epoxy resin (B1) to the acrylic elastomer (B2) is [(B1) / (B2)] = about 2.
Then, using a rheometer “AR-G2” manufactured by TA Instruments Inc., it is fixed at a frequency of 1 Hz at a temperature of 25 ° C., and has a storage elasticity in the range of vibration stress of 1.0 to 10,000,000 Pa. When the dynamic viscoelastic properties such as the modulus G ′ were measured, the storage elastic modulus G ′ of the conductive ink of Example 1 at a vibration stress of 50 Pa was 5,400, and tan δ was 0.73.
The viscosity measured under the conditions of 25 degrees and 5 rpm using an E-type viscometer “Viscometer TVH-22” manufactured by Toki Sangyo Co., Ltd. is 210 (mPa · s), and the TI value (2 rpm / 20 rpm) is It was 9.5.
The obtained conductive ink was subjected to various evaluations described later. The results are shown in Table 1.

Examples 2 to 23, Comparative Examples 1 to 27 <Preparation of conductive ink>
Silver powder, binder resin solution, metal chelate, curing agent, and solvent were mixed with a disper at the mixing ratio shown in Tables 1 to 6, and then dispersed with three rolls to prepare a conductive ink in the same manner as in Example 1. , Evaluated in the same way. The results are shown in Tables 1-6.

Examples 24-26 <Preparation of conductive ink>
As shown in Table 3, a binder resin solution, a curing agent, and a solvent were mixed with a disper at the same blending ratio as in Examples 1, 7, and 4 to obtain a resin solution, and the resulting resin solution was divided into half amounts. After mixing the conductive particles (A1) and the conductive particles (A2) with a disper at the blending ratio shown in Table 3 in each resin solution, each mixture is separately dispersed with three rolls and then dispersed. After mixing a half amount of the metal chelate shown in Table 3 in the body with a disper and dispersing with three rolls, each dispersion was mixed with a disper to prepare a conductive ink. Evaluation was performed in the same manner. The results are shown in Table 3.

[Evaluation of conductivity (volume resistivity) and adhesion]
On the corona-treated surface of a 75 μm thick corona-treated polyethylene terephthalate film (hereinafter referred to as “PET film”) using a high-precision screen printer (SERIA manufactured by Tokai Seiki Co., Ltd.), the conductive ink of each example and each comparative example was 15 mm. Screen printing was performed in a pattern shape of × 30 mm and dried in an oven at 150 ° C. for 30 minutes to obtain a plurality of conductive printed materials having a thickness of 8 to 10 μm.
About the obtained printed matter, the film thickness and surface resistance value of an initial state (normal state) were measured, the volume resistivity was calculated | required, and adhesiveness was evaluated further.
Next, each printed matter is exposed to an environment of 130 ° C. for 1000 hours (high-temperature storage test), exposed to an environment of 60 ° C. and 90% RH for 1000 hours (moisture and heat resistance test), and is exposed to an environment of −50 ° C. for 30 hours. The process of exposing for 30 minutes and then in an environment of 150 ° C. for 30 minutes was repeated as 1000 cycles (thermal shock resistance (heat cycle) test), and the volume resistivity and adhesion were evaluated in the same manner as in the initial stage.
Evaluation methods and evaluation criteria are as follows.

<Measurement of film thickness>
The film thickness of the printed matter was measured using an MH-15M type measuring instrument manufactured by Sendai Nikon Corporation.
<Measurement of surface resistance value>
The surface resistance value of the printed matter was measured using a Loresta APMCP-T400 measuring instrument manufactured by Mitsubishi Chemical Corporation in an environment of 25 ° C. and 50% humidity.

<Evaluation of volume resistivity>
The volume resistivity was calculated from the surface resistance value measured by the above method and the film thickness.
A volume resistivity of 8.0 × 10 ⁻⁵ Ω · cm or less is preferable because it can be practically widely used as a conductive material, and a volume resistivity of 5.0 × 10 ⁻⁵ Ω · cm or less is preferable. It is more preferable because it can be used in a wider range of applications. On the other hand, when it is higher than 8.0 × 10 ⁻⁵ , the range of use is limited, which is not preferable.
○: 5.0 × 10 ⁻⁵ Ω · cm or less Δ: higher than 5.0 × 10 ⁻⁵ Ω · cm, 8.0 × 10 ⁻⁵ Ω · cm or less ×: higher than 8.0 × 10 ⁻⁵

<Evaluation of adhesion>
A tape adhesion test was performed in accordance with JIS K5600.
Put a total of 100 squares of 10 squares x 10 squares at a 1 m width interval on the printed surface with a cutter, apply Nichiban cellophane tape (25 mm wide) to the printed surface, peel off rapidly, and leave the remaining squares And evaluated.
○: No peeling (good adhesion)
Δ: Slightly chipped edges of the mass (adhesion is slightly poor but can be used practically)
X: Peeling over 1 square is observed (adhesion failure)

[Evaluation of adhesion to other substrates]
Instead of the corona-treated PET film, an ITO laminated film (manufactured by Nitto Denko Corporation, V270L-TEMP, 75 μm thickness), and the entire surface of this ITO laminated film are etched with hydrochloric acid to remove the ITO layer and a base material (polyethylene terephthalate) Using the conductive inks of each of the examples and comparative examples, a printed matter was obtained in the same manner as in the case of the PET film except that the film was exposed, and the normal (initial) adhesion was evaluated in the same manner. did.

[Evaluation of flexibility]
For the corona-treated surface of the thick corona-treated PET film, using the conductive ink of each example and each comparative example, a wiring pattern having a line width of 300 μm, a line width of 2 mm (L / S = 300 μm / 2000 μm), and a length of 50 mm 10 were screen-printed and dried in an oven at 150 ° C. for 30 minutes to obtain a conductive printed material for evaluation of flexibility having a thickness of 8 to 10 μm.
A test piece of 60 mm × 31 mm was cut out with a circle of 5 mm outside of the print area around 10 wiring patterns. The resistance value between 10 pattern line ends of 50 mm length was measured, and the average value was used as the initial resistance value.
Next, the central portion of the print pattern in the major axis direction of the test piece is bent at 180 degrees in a mountain fold, and a load of 2.0 kg is applied to the bent portion for 5 seconds, and then the test piece is returned to a flat shape and 2.0 kg is applied to the bent portion. After repeating the work of applying the load of 5 seconds for 20 seconds, the resistance value between the ends of the 10 pattern lines having a length of 50 mm was measured in the same manner as in the initial stage, and the average value was obtained to obtain the resistance value after bending. The degree of increase in resistance value before and after bending was calculated and evaluated by the following formula.
Resistance value increase degree (times) = resistance value after bending 20 times / resistance value before bending ○: 1.5 times or less. The resistance fluctuation range by bending is small and good.
Δ: More than 1.5 times and less than 2.5 times. Although there is fluctuation in resistance value due to bending, the practicality as a circuit is maintained and it can be used.
X: It is larger than 2.5 times. Since the resistance value fluctuation due to bending is large and the use range as wiring is remarkably limited, it is not preferable.

[Evaluation of warpage]
On the corona-treated surface of the corona-treated PET film, using the conductive ink of each example and each comparative example, a 50 mm × 50 mm solid portion was screen-printed and dried in a 150 ° C. oven for 30 minutes, and the thickness was 8 to 10 μm. A conductive printed material for warpage evaluation was obtained.
Next, the test piece for warpage evaluation of 55 mm × 55 mm was cut out by making a round on the outer side of the solid part 5 mm. The test piece was heated at 180 ° C. for 1 hour and returned to 25 ° C., then the test piece was placed on a flat table, the heights of the four corners floating from the table were measured, and the average value was obtained. Evaluated.
○: Warpage height is 10 mm or less. The effect of warping due to heat is small and good.
(Triangle | delta): Warp height is larger than 10 mm and 20 mm or less. Despite the influence of warping due to heat, the practicality of the circuit is maintained and it can be used.
X: Warpage height is larger than 20 mm. Since the influence of the warp by heat is large and the use range as wiring is remarkably limited, it is not preferable.

[Evaluation of solvent resistance]
As in the case of resistance measurement and adhesion evaluation, a 15 mm × 30 mm pattern portion provided on a corona-treated PET film was rubbed 20 times with a cotton swab impregnated with methyl ethyl ketone, and dirt (silver paste component) ) Was visually observed to evaluate the solvent resistance.
○: There is almost no dirt on the swab and the solvent resistance is good.
Δ: Some dirt on the cotton swab is observed, but the practicality as a circuit is maintained and it can be used.
X: The cotton swab is very dirty and the wiring may be lost.

[Evaluation of high-definition printability and flatness during high-speed continuous printing]
Using a high-precision screen printing device (SERIA manufactured by Tokai Seiki Co., Ltd.), each of the examples and comparative examples was placed in a 200 mm × 200 mm region of the corona-treated surface of the corona-treated PET film having a thickness of 75 μm under the following conditions. After conducting 20 continuous printings of the following three patterns of conductive ink, drying was performed at 150 ° C. for 30 minutes to obtain a conductive printed material having a thickness of 8 to 10 μm. About the 5th and 20th printed materials The printing state was evaluated.

Pattern 1: 100 fine wiring patterns having a line width of 40 μm and a line width of 60 μm (L / S = 40 μm / 60 μm) Pattern 2: a line width of 300 μm, a line width of 2 mm (L / S = 300 μm / 2000 μm), a line 10 fine wiring patterns with a length of 50 mm Pattern 3: Two 15 mm x 30 mm solid parts

(Screen printing conditions)
・ Screen: Stainless steel plate 650 mesh ・ Emulsion thickness: 15 μm
・ Screen frame: 650x550mm
・ Squeegee polishing angle: 90 ° (flat squeegee)
・ Ski Dia Attack Angle: 70 °
・ Squeegee hardness: 80 °
・ Squeegee speed: 100mm / sec ・ Squeegee printing pressure: 10kg
・ Clearance: 3.5mm

<Thickness degree of fine wiring of pattern 1>
The fine wiring part of the pattern 1 was image | photographed the enlarged photograph (magnification 500 times) using the digital microscope (VHX-900 by Keyence Corporation). The fine line width after printing was read using the small-sized general-purpose image analyzer “LUZEX AP” manufactured by Nireco.
Specifically, for the printed matter on the fifth and twentieth sheets, 8 arbitrary thin lines are selected, the line widths at 460 points per line, total of 8680 are measured, the average line width, and The degree of thin line thickness “(average line width−40 μm) / 40 μm (%)” was determined.
A: Less than 10%. There is no thickening of the line width, and the fine line printability is very good.
○: 10% or more and less than 20%. There is almost no thickening of the line width, and fine line printability is good. Δ: 20% to less than 40%. A slight increase in the line width is recognized, but the fine line printability is practically satisfactory. X: 40% or more. Thickening of line width is recognized and thin line printability is poor

<Shape of fine wiring of pattern 1>
Furthermore, the shape of the fine wiring portion of pattern 1 was evaluated according to the following criteria: ○: The fine wiring portion did not vary in thickness due to meandering, bleed, or wrinkled, and the boundary line of the fine wiring portion was clear and good Met.
Δ: Some variation in thickness due to meandering was observed in the fine wiring part, but it did not bleed or wrinkle, and was practically satisfactory.
X: The fine wiring portion was found to have a variation in thickness due to meandering, bleed and wrinkle, and the boundary line was unclear.

<Printed state of pattern 3 (solid portion)>
As with the fine wiring portion, an enlarged photograph (magnification 500 times) was taken for the solid portion of pattern 3 and evaluated according to the following criteria.
○: No blurring occurred on the entire surface, the linearity of the pattern edge portion was good, and the boundary line was clear.
(Triangle | delta): Although the wrinkle did not arise in the whole surface, the pattern edge part was applied to linearity, such as the meandering or the chip | tip having generate | occur | produced. It was a level where there was no problem in practical use.
X: Severe dripping on the entire surface, meandering or chipping of the pattern edge portion occurred, and it was not practically usable.

<Evaluation of surface flatness (thickness difference (unevenness)) using pattern 2>
For pattern 2, using a non-contact three-dimensional surface shape / roughness measuring machine “New View 5032” manufactured by Zygo Corporation, the height of the printed pattern surface from the film substrate surface is 10 per 50 mm long printed pattern. A total of 100 points and 100 points were measured randomly, and a difference (thickness difference) between the highest value and the lowest value was obtained.
A: The height difference is 7 μm or less.
The flatness in the thickness direction was very excellent, the thickness of the laminated insulating layer could be made thinner, and it was a level that could be easily applied to a wide range of uses.
○: The height difference is larger than 7 μm and 10 μm or less.
It was excellent in flatness in the thickness direction, and was a level applicable to a wide range of uses such as lamination of insulating layers.
Δ: The height difference is larger than 10 μm and 20 μm or less.
When laminating other coatings such as an insulating layer, if the insulating layer was thickened to some extent, it was at a level that could be used practically.
X: The height difference is larger than 20 μm.
When laminating other coatings such as an insulating layer, a part of the conductive print pattern penetrates the insulating layer etc. in an insulating layer having a practical thickness, etc. .

The bisphenol type epoxy resin (B1) used in the present invention has an epoxy group and a hydroxyl group, and it is important that the weight average molecular weight (Mw) in terms of polystyrene is 10,000 to 100,000, preferably It is 10,000-80,000, More preferably, it is 30,000-70,000. When the weight average molecular weight of the epoxy resin is less than 10,000, even when an appropriate amount of a metal chelate as described later is used, a sufficient storage elastic modulus G ′ for forming fine wiring by screen printing cannot be obtained. If it is greater than 1,000, the solubility in the solvent is extremely deteriorated, or the storage elastic modulus G ′ becomes too high, and screen printing becomes impossible.
The weight average molecular weight in the present invention refers to two resins in series of “LF-604” (GPC column for rapid analysis: 6 mm ID × 150 mm size) manufactured by Showa Denko KK as a gel column using a resin dissolved in THF (tetrahydrofuran). Connected GPC (Gel Permeation Chromatography: Liquid Chromatography for Separating and Quantifying Substances Dissolved in Solvent by Difference in Molecular Size) “HPLC-8020”, Flow Rate 0.6 ml / min, Column It means a value calculated in terms of polystyrene based on data measured at a temperature of 40 ° C.

The present invention contains two kinds of conductive particles having different tap densities in a specific ratio, and also uses a specific bisphenol type epoxy resin and an acrylic elastomer as a so-called binder resin in a specific ratio, and further a specific amount of metal The above object was achieved by containing a chelate and a curing agent.
That is, the present invention has a tap density of 4.5 to 7 (g / cm ³ ), a D50 particle diameter of 0.1 to ³ μm of conductive particles (A1), and a tap density of 0.5 to 3. 5 (g / cm ³ ) and D50 particle diameters of 0.1 to ³ μm of conductive particles (A2) in a ratio of 0.25 ≦ [(A1) / (A2)] ≦ 4 (weight ratio) Contained in
A polystyrene-reduced weight average molecular weight (Mw) of 10,000 to 100,000, a hydroxyl value of 2 to 300 (mgKOH / g) , a glass transition temperature of 40 to 150 ° C., a bisphenol type epoxy resin (B1), and glass An acrylic elastomer (B2) having a transition temperature of −50 to 25 ° C. and a Mooney viscosity of 10 to 90 in a ratio of 9 ≧ [(B1) / (B2)] ≧ 0.1 (weight ratio);
0.2 to 20 parts by weight of metal chelate (C) is contained with respect to 100 parts by weight of the total of the epoxy resin (B1) and the acrylic elastomer (B2),
A curing agent having a functional group capable of reacting with at least one of a hydroxyl group and an epoxy group of the epoxy resin with respect to a total of 100 parts by weight of the epoxy resin (B1) and the acrylic elastomer (B2) (D 1) to 40 parts by weight,
The present invention relates to a conductive ink in which the total amount of (A1) and (A2) is 55 to 97.5% by weight in 100% by weight of the components excluding the organic solvent.

Further, a bisphenol type epoxy resin used in the present invention (B1) has a glass transition temperature (hereinafter, Tg hereinafter) is is 40 to 150 ° C., it is favorable preferable is 50 to 120 ° C..
When Tg is lower than 40 ° C., the heat resistance of the cured film of the conductive ink may be deteriorated, and when Tg is higher than 150 ° C., the flexibility of the cured film may be significantly impaired.
The Tg of the bisphenol-type epoxy resin (B1) is a dry resin (powder, droplet, or slice), which is −50 ° C. to 5 ° C./min using a differential calorimeter (DSC). The measurement was performed under the condition of 300 ° C., and the value was determined by the inflection point of the calorimetric curve.

Claims (10)

Conductive particles (A1) having a tap density of 4.5 to 7 (g / cm ³ ) and a D50 particle diameter of 0.1 to ³ μm, and a tap density of 0.5 to 3.5 (g / cm ^3). And D50 conductive particles (A2) having a particle diameter of 0.1 to 3 μm in a ratio of 0.25 ≦ [(A1) / (A2)] ≦ 4 (weight ratio),
A polystyrene-reduced weight average molecular weight (Mw) of 10,000 to 100,000, a bisphenol type epoxy resin (B1) having a hydroxyl value of 2 to 300 (mgKOH / g), a glass transition temperature of −50 to 25 ° C., An acrylic elastomer (B2) having a Mooney viscosity of 10 to 90 in a ratio of 9 ≧ [(B1) / (B2)] ≧ 0.1 (weight ratio);
0.2 to 20 parts by weight of metal chelate (C) is contained with respect to 100 parts by weight of the total of the epoxy resin (B1) and the acrylic elastomer (B2),
A curing agent having a functional group capable of reacting with at least one of a hydroxyl group and an epoxy group of the epoxy resin with respect to a total of 100 parts by weight of the epoxy resin (B1) and the acrylic elastomer (B2) (D 1) to 40 parts by weight,
The electroconductive ink whose total amount of (A1) and (A2) is 55-97.5 weight% in the total 100 weight% of the components except an organic solvent.   The conductive ink according to claim 1, wherein the conductive particles (A1) and (A2) are silver or silver-plated powder.   The conductive ink according to claim 1 or 2, wherein the metal chelate (C) is at least one selected from the group consisting of an aluminum chelate, a titanium chelate and a zirconium chelate.   The hardener (D) is at least one selected from the group consisting of an isocyanate compound, an amine compound, an acid anhydride compound, a mercapto compound, an imidazole compound, a dicyandiamide compound, and an organic acid hydrazide compound. 2. The conductive ink according to item 1.   The conductive ink according to claim 3 or 4, wherein the metal chelate (C) is an aluminum chelate.   The conductive ink according to claim 5, wherein the aluminum chelate (C) has a group selected from the group consisting of an acetylacetonate group, a methylacetoacetate group, and an ethylacetoacetate group.   It is an object for screen printing, The electroconductive ink of any one of Claims 1-6 characterized by the above-mentioned. A substrate;
A conductive pattern formed on the substrate,
The laminated body with a conductive pattern in which the said conductive pattern is formed with the conductive ink of any one of Claims 1-7.   The laminated body with a conductive pattern according to claim 8, further comprising an insulating layer laminated so as to cover the conductive pattern. Comprising a step of forming a conductive pattern having a desired pattern shape on a substrate by screen printing;
The said conductive pattern is a manufacturing method of the laminated body with a conductive pattern using the conductive ink of any one of Claims 1-7.