JP2008106121A - Conductive ink, conductive circuit and noncontact medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive ink enabling high-speed printing of a printed antenna having a thickness of about half of the thickness of a conventional antenna by a flexographic printing or a gravure printing, realizing sufficiently low volume resistivity, and having excellent stability and fluidity of the ink and to provide a noncontact medium having a conductive circuit formed by a conventional printing method and contributing to the mass productivity, the cost reduction and the saving of energy. <P>SOLUTION: The conductive ink containing an electrically conductive substance and a binder component is produced by using a flaky metal powder having a BET specific surface area of 0.5-2.0 m<SP>2</SP>/g and a tap density of 2-5 g/cm<SP>3</SP>as the conductive substance and using a chlorinated polyolefin resin dissolved in a hydrocarbon solvent. The noncontact medium has a conductive circuit formed on a substrate by the gravure printing of the conductive ink or by the flexographic printing with a flexographic printing plate resistant to a hydrocarbon solvent and an IC chip mounted on the substrate in a state electrically connected to the conductor circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printed matter formed by printing or coating on a substrate using a conductive ink, and further, a conductive circuit using a conductive ink and an IC module mounted in a conductive state with the conductive circuit; It is related with the non-contact type medium which comprises. Furthermore, in detail, it is excellent in the stability and fluidity of the ink that makes it possible to print a printed antenna having a film thickness about half that of the conventional film by gravure printing or flexographic printing, and a sufficiently low volume resistance value can be obtained. The present invention relates to provision of a non-contact type medium that includes a conductive circuit formed by conductive ink and gravure printing and flexographic printing methods, and contributes to mass productivity, cost reduction, and energy saving.

  Thin film formation for electronic parts or electromagnetic shielding or patterning of conductive circuits is generally performed by printing a circuit or circuit pattern using a thermosetting or thermoplastic conductive ink, and sintering by heat treatment or copper. Etching from a stretched substrate is known.

As an example of the sintering method, JP 2000-305260 A discloses a photosensitive paste comprising an alkali-soluble negative photosensitive resin composition, a photopolymerization initiator, metal powder, and metal ultrafine particles as a photosensitive conductive paste. Is disclosed. In this publication, after patterning a photosensitive resin composition, an organic component is volatilized in a firing furnace such as an electric furnace or a belt furnace, and an inorganic powder is fired to form a conductive pattern film. The firing atmosphere is 500 ° C. or higher in the air, a nitrogen atmosphere, or a hydrogen atmosphere, and a large facility is required.
On the other hand, with respect to the etching method, the surface or shape of the metal is chemically or electrochemically dissolved and removed, and a processing technique in a broad sense including the surface treatment is used. Etching is a kind of chemical processing, and is mainly performed to obtain a desired pattern shape on the metal surface. However, since the process is generally complicated and waste liquid treatment is necessary in the subsequent process, there is a problem. Many. Moreover, since the conductive circuit formed by the etching method is formed only of a metal such as aluminum or copper, there is a problem that it is weak against physical impact such as bending.

  The conductive ink can be expected to reduce the size and weight of electronic parts, improve productivity, and reduce costs, and can easily impart conductivity by printing or coating on a substrate and drying. In this drying and curing process, demand can be rapidly increased in recent years because it can be performed at a low temperature without applying a high temperature to the substrate or the electronic component.

  Among thermosetting conductive inks, those using an inorganic substance such as glass frit as a binder component must be heated at a high temperature after being applied or printed on a substrate. Curing by heating requires a great deal of energy, time, and floor space for equipment installation, which is not only uneconomical, but also has the following major limitations.

  That is, a conductive ink using an inorganic substance such as glass frit as a binder usually requires baking at 800 ° C. or higher, and thus cannot be applied to a synthetic resin base material. On the other hand, the conductive ink using a thermosetting resin as a binder can be applied to a synthetic resin-based substrate, but the substrate is deformed by overheating when the conductive ink is cured, and the resulting print is obtained. There were major obstacles such as hindering the mounting of components in the post-process using the wiring circuit.

  Further, as a thermoplastic conductive ink, as disclosed in Japanese Patent Publication No. 2974256, a conductive ink using at least one thermoplastic vinyl acetate resin / vinyl chloride / dicarboxylic acid multi-polymer resin is disclosed. However, the printing method requires a dry film thickness of 25 μm to obtain a surface resistivity of 9 to 22 mΩ / □ on a silk screen.

In addition, as disclosed in JP-A-2005-56778, a conductive ink using silver powder having a thickness of 1300 angstroms or less is disclosed, but silk screen printing is used as a means for printing a circuit, In order to obtain a specific resistance of 10 ⁻⁵ Ω · cm, an ink dry film thickness of 6 to 8 μm is required.
On the other hand, in order to realize a ubiquitous society as it is now, practical application of IC tags and RFID tags is being studied in various directions, and printing is a means for manufacturing large numbers of IC tags and RFID tags in a short period of time. Antenna circuit formation is being put into practical use. However, since flat silk screen printing has been the mainstream in conventional printed antennas, the printing speed is as extremely low as 1 to 2 m / min and productivity is poor. Recently, methods for printing conductive ink by rotary silk screen printing have been disclosed in Japanese Patent Application Laid-Open Nos. 2003-110225 and 2005-259546, and printing is the most important point required by this method. The speed is not disclosed. The rotary silk screen printing generally has a printing speed of 5 to 20 m / min, which is 5 to 10 times that of flat silk screen printing. In addition, even if the finest screen mesh is used for flat silk screens and rotary silk screens, the thickness of the screen is 20 μm. In order to reduce the amount of expensive silver powder used as a conductive material, the ink dry film thickness should be less than that. It is difficult to reduce the thickness to 5 μm or less.
JP 2000-305260 A Japanese Patent Publication No. 2974256 JP 2005-56778 A JP 2003-110225 A JP 2005-259546 A

In the formation of conductive circuits by printing using conventional conductive ink, flat silk screen printing and rotary silk screen printing have been put to practical use. In flat silk screen printing, the printing speed is 1 to 2 m. / Min, 5 to 20m / min for rotary silk screen printing. In order to realize a ubiquitous society as it is now, practical application of IC tags and RFID tags is being studied in various directions. It is difficult to manufacture IC tags and RFID tags. Further, in order to reduce the amount of expensive silver powder used as the conductive material, it is difficult to reduce the thickness of the ink dry film, for example, 5 μm or less.
The present invention performs gravure or flexographic printing at a printing speed of 50 to 100 m / min, makes it possible to produce a uniform coating film with a dry film thickness of 1 to 3 μm in a large amount and in a short time, and the obtained conductivity It is an object of the present invention to provide a conductive ink and a non-contact type medium having excellent electrical performance with a circuit surface resistivity of 500 mΩ / □.

In the present invention, a flaky metal powder having a BET specific surface area of 0.5 to 2.0 m ² / g and a tap density of ^{2 to 5} g / cm ³ is used as the conductive material. A conductive ink containing 75 to 95% by weight of solids in the ink, and further containing a chlorinated polyolefin resin dissolved using a hydrocarbon solvent as a binder component, and further, gravure printing or a hydrocarbon solvent The problem can be solved by performing flexographic printing using a flexographic plate that does not swell due to.
More specifically, when printing by flexographic printing using the conductive ink of the present invention, the conventional flexographic plate is resistant to alcohol solvents, but the plate swells with aromatic and aliphatic hydrocarbon solvents. As a result, there was a restriction that printing was not possible. As a result of various studies of the present invention, it has been found that some water-developable flexographic plates can be used for printing a resin dissolved in an aromatic and aliphatic hydrocarbon solvent without being swollen.
The metal powder is preferably silver powder.

In the conductive ink of the present invention, the chlorinated polyolefin resin used as the binder has good wettability with the flaky metal powder having a BET specific surface area of 0.5 to 2.0 m ² / g and a tap density of ^{2 to 5} g / cm ^3. A uniform dispersion state is obtained, and a hydrocarbon solvent that dissolves chlorinated polyolefin resin is also added around the metal powder to add it when processing the metal powder into flakes and suppress aggregation of the metal powder. The fluidity of the resulting ink was improved because of its good compatibility with the lubricant to be used. This makes it possible to perform gravure printing or flexographic printing at high speed, and by obtaining a uniform thin film, a very low surface resistivity can be achieved, contributing to cost reduction by mass production. The new non-contact type IC media can be spread at a low cost in the future.

Hereinafter, the present invention will be described in more detail based on embodiments, but the present invention is not limited to these embodiments unless departing from the technical idea of the present invention.
The binder component used in the conductive ink according to the present invention is a synthetic resin made of chlorinated polyolefin. More specifically, chlorinated polyethylene and chlorinated polypropylene having a chlorine content of 60% or more are preferable. A chlorinated polyolefin having a content of less than 60% may be used, and a conductive material is a flaky metal powder having a BET specific surface area of 0.5 to 2.0 m ² / g and a tap density of ^{2 to 5} g / cm ^3. With good adhesion and flexibility to the base material and good fluidity, it also has excellent printability, and has a surface resistivity of 500 mΩ / □ or less when dried at a low temperature of 100 ° C. or lower. can get.

  For conductive ink, it is preferable to use silver powder as the conductive material, but other conductive materials such as silver-plated copper, silver-copper composite, silver-copper alloy, amorphous copper, and other metals as necessary. Inorganic powder coated with these metals, silver oxide, indium oxide, antimony oxide, zinc oxide, tin oxide, antimony-doped tin oxide, metal oxides such as indium-tin composite oxide, carbon black, graphite, etc. be able to. These conductive materials may be used alone or in combination of two or more.

  The conductive ink of the present invention can be used in combination with another organic resin in addition to the chlorinated polyolefin resin. Other organic resins include polyester resin, urethane-modified polyester resin, epoxy-modified polyester resin, various modified polyester resins such as vinyl chloride, vinyl acetate copolymer resin, acrylic-modified polyester, polyether urethane resin, polycarbonate urethane resin, epoxy resin And modified celluloses such as phenol resin, acrylic resin, polyamideimide, nitrocellulose, cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP).

  The chlorinated polyolefin used in the conductive ink according to the present invention is composed of aliphatic hydrocarbon solvents such as n-heptane, n-hexane, cyclohexane, methylcyclohexane and ethylcyclohexane, aromatic hydrocarbon solvents such as toluene, xylene and alkylbenzene, and Although it dissolves in petroleum-based mixed solvents, etc., it can be used in combination with ester solvents, ketone solvents, glycol ether solvents, alcohol solvents, etc. You can also.

  Examples of ester solvents include methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, (iso) amyl acetate, cyclohexyl acetate, ethyl lactate, and 3-methoxybutyl acetate. , Acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl amyl ketone, isophorone, cyclohexanone and the like. The glycol ether solvents include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol mono n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol. Mono n-propyl ether, propylene glycol mono n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono n-propyl ether, and acetates of these monoethers, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, etc. Zia Kill ethers and the like.

  Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  Glycol solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether , Diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol Bruno ethyl ether, propylene glycol isopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 1─ butoxyethoxy propanol, 1-methoxy-2-propyl acetate and the like.

   Examples of the alcohol solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, cyclohexanol, 3-methoxybutanol, diacetone alcohol and the like. Other liquid media include dimethyl carbonate, ethyl methyl carbonate, and di-n-butyl carbonate.

  Examples of the flexographic plate that does not swell with an aromatic or aliphatic hydrocarbon solvent used when printing by flexographic printing using the conductive ink of the present invention include Toyobo's printite plate series, etc. It is not limited to this.

Finally, a non-contact type medium including a conductive circuit formed using the conductive ink of the present invention and an IC chip mounted in a conductive state with the conductive circuit will be described.
The conductive ink of the present invention can form a conductive circuit by printing on one or both sides of a substrate such as paper or plastic using a printing method such as flexographic printing or gravure printing according to the intended use. .

As the paper substrate, various processed papers such as coated paper, non-coated paper, synthetic paper, polyethylene coated paper, impregnated paper, water-resistant processed paper, insulating processed paper, and stretch processed paper can be used. In order to obtain a stable resistance value, coated paper and processed paper are preferable. In the case of coated paper, the higher the smoothness, the better.
Plastic base materials include polyester, polyethylene, polypropylene, cellophane, vinyl chloride, vinylidene chloride, polystyrene, vinyl alcohol, ethylene-vinyl alcohol, nylon, polyimide, polycarbonate and other plastic tags used as cards. Material can be used.

  By using the conductive ink of the present invention, a conductive circuit can be formed by a normal printing method, so that design utilizing existing equipment is possible. In other words, it is possible to print and form a conductive circuit as it is after performing normal printing to improve the design of non-contact media such as a pattern, so circuit formation that has been conventionally performed by etching or transfer methods Compared to the law, it is far superior in terms of productivity, initial investment cost, and running cost.

In the process before printing and forming the conductive circuit, an anchor coating agent or various varnishes may be applied to the base material for the purpose of improving the adhesion to the base material. Moreover, you may apply an overprint varnish, various coating agents, etc. for the purpose of circuit protection after conductive circuit printing. As these various varnishes and coating agents, any of ordinary heat drying type and active energy ray curable type can be used.
Alternatively, a non-contact medium can be obtained by applying an adhesive on a conductive circuit and bonding a paper substrate or a plastic film on which a pattern or the like is printed as it is, or laminating by plastic melt extrusion or the like. Of course, it is also possible to use a substrate on which a pressure-sensitive adhesive or adhesive has been applied in advance.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.
[Binder 1]
60 parts of Nippon Paper Chemicals' chlorinated polyolefin resin Supercron HP620 (chlorine content 65-69%, softening temperature about 130 ° C.) and Maruzen Petrochemical's aromatic hydrocarbon solvent Swazol 1000 are put into a round bottom flask. The binder 1 was obtained by stirring and dissolving at 70 ° C. for 3 hours.
[Binder 2]
Nippon Paper Chemicals' chlorinated polyolefin resin Super Clone HP1200 (chlorine content 65-69%, softening temperature 130 ° C) (60 parts, Maruzen Petrochemical's aromatic hydrocarbon solvent Swazol 1000 is charged into a 40-part round bottom flask. Then, the mixture was stirred and dissolved at 70 ° C. for 3 hours to obtain a binder 2.
[Binder 3]
60 parts of Nippon Paper Chemicals' chlorinated polyolefin resin Supercron HP205 (chlorine content 65-69%, softening temperature about 200 ° C) and 40 parts of Maruzen Petrochemical's aromatic hydrocarbon solvent Swazol 1000 are put into a round bottom flask. The binder 3 was obtained by stirring and dissolving at 70 ° C. for 3 hours.
[Binder 4]
60 parts of Nippon Paper Chemicals chlorinated polyolefin resin Supercron 803 MW (chlorine content 29.5%, softening temperature about 80-90 ° C), 40 parts of Maruzen Petrochemical's aromatic hydrocarbon solvent Swazol 1000 in a round bottom flask The binder 4 was obtained by stirring and dissolving at 70 ° C. for 3 hours.
[Binder 5]
Arakawa Chemical's polyurethane varnish KL-593 (polyurethane resin, ethyl acetate, isopropyl alcohol) was used as the binder 5.
[Silver powder A]
A flaky silver sill coat AgC-A (BET specific surface area 0.8 m ³ / g, tap density 3.5 g / cm ³ ) manufactured by Fukuda Metal Foil Powder Industry was used as silver powder A.
[Silver powder B]
The flaky silver OK-6P (BET specific surface area 1.7 “m ³ / g, tap density 4.6 g / cm ³ ” manufactured by Mitsui Mining & Mining Co., Ltd. was defined as silver powder B.
[Silver powder C]
Spherical silver TPS (BET specific surface area 1.9 m ³ / g, tap density 1.1 g / cm ³ ) manufactured by Mitsui Mining & Mining was used as silver powder C.
[Silver powder D]
SINO-PLATINUM-made flaky silver FAGL-1 (BET specific surface area 5.6 m ³ / g, tap density 2.9 g / cm ³ ) was used as silver powder D.

[Examples 1-5, Comparative Examples 1-3]
Silver powder, binder, and solvent are mixed with a disper at the blending ratio shown in Table 1 to prepare a conductive ink, and a gravure plate having a plate depth of 40 μm is printed on a gravure printing machine with a printing speed of 70 m / min and a drying temperature of 80 ° C. A solid drawing of 50 mm × 80 mm was printed under the printing conditions.
[Examples 6 to 10, Comparative Examples 4 to 6]
An anilox roll of 200 lines / inch anilox roll and an anilox roll having a cell capacity of 20 cm ³ / m ² and the examples 6 to 10 and the comparative examples 5 to 6 are flexographic plates. Using Toyobo Printite BF170B, which is resistant to hydrocarbon solvents, Comparative Example 4 uses a DPU plate made by DuPont, which is resistant to alcohol solvents, at a printing speed of 70 m / min and a drying temperature of 80 ° C. A solid drawing of 50 mm × 80 mm was printed.
The physical properties of the obtained printed material are shown in Table 2.

The surface resistivity of the obtained printed matter was measured with JISK 7149 (resistivity test method using conductive plastic 4-probe method) using a resistivity meter Loresta GP manufactured by Dia Instruments, and the film thickness was measured by Sendai Nikon Measurement was performed using a MH-15M type measuring instrument.
Further, in order to compare the transition state of the obtained printed matter, the transmission density was measured with a Macbeth transmission density meter TD391. Here, the higher the transmission density, the better the printed matter with less missing.
Furthermore, visual evaluation was performed about the surface state of the obtained printed matter.
Printed surface condition ○ ・ ・ ・ ・ Smooth and good
△ ・ ・ ・ ・ Intermediate
× ··· Many irregularities and poor [Examples 1 to 10]
Gravure conductive ink using chlorinated polyolefin resin dissolved in hydrocarbon solvent using flaky metal powder with BET specific surface area of 0.5-2.0 m ² / g and tap density of 2-5 g / cm ³ By printing, a very uniform and continuous thin film was obtained, and the surface resistivity was 100 mΩ / □ or less with respect to a film thickness of 2 to 3 μm, showing very good conductivity.
In addition, by using flexographic printing of ink of the same composition using a flexographic plate that is resistant to hydrocarbon solvents, a very uniform and continuous thin film can be obtained, and the surface resistivity is 2 to 3 μm. On the other hand, it showed very good conductivity of 100 to 200 mΩ / □ or less.
[Comparative Examples 1 and 4]
Comparative Example 3 (gravure printing) in which a flaky metal powder having a BET specific surface area of 0.5 to 2.0 m ² / g and a tap density of ^{2 to 5} g / cm ³ was used but a chlorinated polyolefin resin was not used as a binder component In Comparative Example 4 (flexographic printing), the transmission density was low and the amount of omission was low, the surface condition was inferior, and the surface resistivity increased.
[Comparative Examples 2 and 5]
BET specific surface area is 0.5 to 2.0 m ² / g, but both Comparative Example 2 (gravure printing) and Comparative Example 5 (flexo printing) using spherical silver powder deviating from a tap density of ^{2 to 5} g / cm ³ are used. Although the transmission density was relatively high and the surface condition was good, there were few contacts between silver powders, and the surface resistivity was remarkably increased.
[Comparative Examples 3 and 6]
BET specific surface area 0.5-2.0 m ² / g, tap density 2-5 g / cm ³ or more Comparative Example 3 (gravure printing) using flaky silver powder Comparative Example 6 (flexographic printing) is both gravure printing and flexographic printing The transfer of ink to the PET substrate was poor, and the surface resistivity was significantly increased.

The conductive ink of the present invention makes it possible to produce a large quantity of good conductivity in a short period of time with a film thickness less than half that of the conventional conductive ink, and suppresses the consumption of precious metal and expensive silver and mass production. In the future, new non-contact type IC media can be spread at low cost.

Claims (5)

In a conductive ink containing a conductive substance and a binder component, a flaky metal powder having a BET specific surface area of 0.5 to 2.0 m ² / g and a tap density of ^{2 to 5} g / cm ³ is used as the conductive substance. A conductive ink characterized in that the flaky metal powder contains 75 to 95% by weight of the solid content in the conductive ink, and the binder component is a chlorinated polyolefin resin.   2. The conductive ink according to claim 1, wherein the solvent for dissolving the binder component uses a hydrocarbon solvent.   A conductive circuit is formed on a substrate by printing the conductive circuit by gravure printing or flexographic printing using the conductive ink according to any one of claims 1 to 2 and drying the conductive circuit. Circuit manufacturing method.   A method for producing a conductive circuit, wherein the conductive circuit according to claim 1 is formed using a flexographic plate that does not swell with a hydrocarbon solvent.   A non-contact type medium in which the conductive circuit and the IC chip according to claim 3 are stacked on a base material.