JP2022036917A - Conductive composition - Google Patents

Abstract

To provide a conductive composition which is difficult to be changed in a line width of a wiring pattern and viscosity of a composition before and after restart of printing when printing is restarted after printing has been stopped for a constant time, and is excellent in printability and conductivity.SOLUTION: A conductive composition contains (a) 0.1-5 mass% of polyethylene glycol having an average molecular weight of 200-2,000, (b) 0.1-5 mass% of an aliphatic monocarboxylic acid having 8 to 18 carbon atoms, (c) 60-95 mass% of conductive particles, and (d) 1-30 mass% of a binder resin.SELECTED DRAWING: None

Description

The present invention relates to a conductive composition which can maintain a wet state for a long time when the composition before heating is allowed to stand and has excellent printability and conductivity.

In recent years, due to the growing awareness of safety and the environment, it is required to reduce the amount of chemicals used that affect the human body and the environment. In the wiring forming method for electronic components, the conventional wet etching method that uses a large amount of chemical solution is being replaced with a printing method that uses a relatively small amount of chemical solution. Among them, the development of wiring forming technology using a screen printing machine, which is a general-purpose printing method, is being actively carried out, and research and development of a conductive paste suitable for screen printing as a material thereof is being promoted. The conductive paste is required to have various properties necessary for the development of the target product, such as its conductivity and adhesion to the substrate to be coated. Among them, printability is a characteristic that is particularly strongly required from the viewpoint of productivity, and a conductive paste having excellent printability is strongly demanded. For example, Patent Document 1 discloses a conductive paste having excellent fine line printability and having a print line width that does not easily change.

In wiring formation using screen printing, a conductive paste capable of continuously printing a wiring pattern having the same line width for a long time is preferable in terms of productivity. However, in the actual manufacturing process, printing is frequently stopped for a long time due to work reasons such as inspection of printed patterns and inspection of printing machines. For example, when screen printing is performed using the conductive paste of Patent Document 1, when printing is restarted after printing is stopped for a certain period of time, the mesh is clogged due to the conductive paste drying on the screen plate. The thickening caused by the volatilization of the solvent in the conductive paste causes defects such as blurring in the wiring pattern after resuming printing, and the line width of the wiring pattern changes significantly before and after resuming printing. There is a point.
That is, when screen printing is stopped for a certain period of time using the above-mentioned conductive paste, there is a possibility that the resistance value may increase due to the variation in the line width of the wiring pattern or the wire may be broken due to blurring depending on the length of the stop time.

Japanese Unexamined Patent Publication No. 2014-67492

The problem to be solved by the present invention is that when printing is restarted after printing is stopped for a certain period of time, the line width of the wiring pattern and the viscosity of the composition are unlikely to change before and after printing is restarted, and the printability and conductivity are excellent. It is to provide a conductive composition.

As a result of repeated studies to solve the above problems, the present inventors have found, in addition to the conductive particles and the binder resin, a specific component having excellent dispersion stability of the conductive particles and a wet state of the composition. We have found that it is possible to provide a conductive composition that can solve the above-mentioned problems by blending with a specific component that can be maintained for a long time, and have completed the present invention.

That is, in the present invention, (a) polyethylene glycol having an average molecular weight of 200 to 2,000 is 0.1 to 5% by mass, and (b) an aliphatic monocarboxylic acid having 8 to 18 carbon atoms is 0.1 to 5 by mass. It is a conductive composition containing (c) 60 to 95% by mass of conductive particles and (d) 1 to 30% by mass of a binder resin.

According to the conductive composition of the present invention, it can be used as a wiring forming material having excellent conductivity and printability, and when printing is restarted after printing is stopped for a certain period of time, the line width of the wiring pattern before and after printing is restarted The effect that the viscosity of the composition does not change easily can be obtained. Therefore, it is possible to print a wiring pattern in which the resistance value is unlikely to increase or disconnection is unlikely to occur.

Hereinafter, embodiments of the present invention will be described.
In addition, the numerical range defined by using the symbol "-" in this specification shall include the numerical values at both ends (upper limit and lower limit) of "-". For example, "2 to 5" represents 2 or more and 5 or less.
Further, if a concentration or amount is specified, any higher concentration or amount can be associated with any lower concentration or amount. For example, when there is a description of "2 to 10% by mass" and "preferably 4 to 8% by mass", "2 to 4% by mass", "2 to 8% by mass", "4 to 10% by mass" and "8". The description of "~ 10% by mass" is also included.

The conductive composition of the present invention comprises (a) polyethylene glycol having an average molecular weight of 200 to 2,000, (b) an aliphatic monocarboxylic acid having 8 to 18 carbon atoms, (c) conductive particles, and (d). ) Contains binder resin. Hereinafter, each component will be described.
The content of each of the above components (a), (b), (c) and (d) is the ratio of each content of the components (a), (b), (c) and (d) to the total value. (Mass%).

[Component (a): Polyethylene glycol]
The component (a) used in the present invention is polyethylene glycol, the average molecular weight thereof is 200 to 2,000, and from the viewpoint of maintaining wettability, it is preferably 400 to 1,500, more preferably 500 to 800. These can be used alone or in combination of two or more.

The average molecular weight of polyethylene glycol can be measured by a method of calculating the average molecular weight based on the hydroxyl value measured according to JIS K1557.

The content of the component (a) is 0.1 to 5% by mass. From the viewpoint of maintaining wettability, it is preferably 0.2 to 5% by mass, more preferably 0.3 to 5% by mass, and further preferably 0.5 to 5% by mass.
On the other hand, from the viewpoint of the conductivity of the cured film, it is preferably 0.1 to 4% by mass, more preferably 0.1 to 3% by mass, and further preferably 0.1 to 2% by mass.
If the content of the component (a) is too small, it becomes difficult to exhibit good wettability and it becomes difficult to maintain the wettability for a long time, so that the line width of the wiring pattern tends to change before and after resuming printing. There is. Further, if the content of the component (a) is too large, the conductivity of the conductive composition may decrease.

[Component (b): Aliphatic monocarboxylic acid]
The component (b) used in the present invention is an aliphatic monocarboxylic acid having 8 to 18 carbon atoms. Examples of the aliphatic monocarboxylic acid include a linear saturated aliphatic monocarboxylic acid, a linear unsaturated aliphatic monocarboxylic acid, a branched saturated aliphatic monocarboxylic acid, and a branched unsaturated aliphatic monocarboxylic acid. One selected from the above compounds may be used alone, or two or more thereof may be used in combination.

Examples of the linear saturated aliphatic monocarboxylic acid having 8 to 18 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stear. Acids and the like can be mentioned. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 18 carbon atoms include myristoleic acid, palmitoleic acid, petroselinic acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 18 carbon atoms include 2-ethylhexanoic acid.

As the component (b), a linear saturated aliphatic monocarboxylic acid having 8 to 18 carbon atoms is preferable from the viewpoint of conductivity. Further, the linear saturated aliphatic monocarboxylic acid preferably has 12 to 18 carbon atoms, more preferably 12 to 14 carbon atoms, and particularly preferably 12 carbon atoms.

The content of the component (b) is 0.1 to 5% by mass. From the viewpoint of suppressing the change in viscosity, it is preferably 0.3 to 5% by mass, more preferably 0.5 to 5% by mass, and further preferably 1 to 5% by mass.
On the other hand, from the viewpoint of the conductivity of the cured film, it is preferably 0.1 to 4% by mass, more preferably 0.1 to 3.5% by mass, and further preferably 0.1 to 3% by mass.
If the content of the component (b) is too small, the viscosity of the conductive composition may easily increase. Further, if the content of the component (b) is too large, the conductivity of the conductive composition may decrease.

[Component (c): Conductive particles]
The component (c) used in the present invention is a conductive particle, and for example, an inorganic conductive particle such as a copper particle can be used. The copper particles may be composed of only copper, but may further contain a metal other than copper such as silver and platinum, a metal oxide, and a metal sulfide. When the copper particles further contain a metal other than copper, a metal oxide, and a metal sulfide, the mass ratio of copper in the copper particles is preferably 50% by mass or more. Further, the copper particles may have a shape in which a surface layer or protrusions are formed.

Commercially available conductive particles may be used as they are, but it is preferable to use surface-coated conductive particles for the purpose of improving oxidation resistance and the like. Above all, it is preferable to use surface-coated conductive particles whose surface is coated with an amine compound, and it is more preferable to use surface-coated conductive particles whose surface is coated with an amine compound represented by the following formula (1).

(In equation (1),
m is an integer of 0 to 3, n is an integer of 0 to 2, and so on.
When n = 0, m is one of 0 to 3 and
When n = 1 or n = 2, m is either 1 to 3. )

The surface-coated conductive particles whose surface is coated with an amine compound such as the amine compound represented by the above formula (1) are further coated with an aliphatic monocarboxylic acid from the viewpoint of obtaining better oxidation resistance. It is preferable to use conductive particles.
As a result, the surface of the conductive particles is coated with the first coating layer formed of the amine compound and the second coating layer formed of the aliphatic monocarboxylic acid. Preferably, the first coating layer is formed on the surface of the conductive particles and the second coating layer is formed on the first coating layer.

As the aliphatic monocarboxylic acid forming the second coating layer, an aliphatic monocarboxylic acid having 8 to 20 carbon atoms is preferable. Examples of the aliphatic monocarboxylic acid include a linear saturated aliphatic monocarboxylic acid, a linear unsaturated aliphatic monocarboxylic acid, a branched saturated aliphatic monocarboxylic acid, and a branched unsaturated aliphatic monocarboxylic acid.
Examples of the linear saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecic acid, lauric acid, tridecanoic acid, myristic acid, pentadecic acid, palmitic acid, margaric acid, and stear. Acids, nonadesilic acid, lauric acid and the like can be mentioned. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include myristoleic acid, palmitoleic acid, petroselinic acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include 2-ethylhexanoic acid.
As the aliphatic monocarboxylic acid, one selected from the above compounds may be used alone, or two or more thereof may be used in combination.
From the viewpoint of the dispersibility of the surface-coated conductive particles, it is preferable to use one having the same structure and carbon number as that of the aliphatic monocarboxylic acid of the component (b) to be used.

The method for producing the surface-coated conductive particles is not particularly limited. As a method for obtaining surface-coated conductive particles whose surface is coated with an amine compound, for example, the conductive particles are washed with an aqueous solution of ammonium chloride or the like, and then the washed conductive particles are added to the solution of the amine compound. Examples include a method of heating as needed.
As a method for producing surface-coated conductive particles coated with a first coating layer formed of an amine compound and a second coating layer formed of an aliphatic monocarboxylic acid, for example, the surface is coated with an amine compound. Examples thereof include a method of adding surface-coated conductive particles to a solution of an aliphatic monocarboxylic acid. After being added to the solution of the aliphatic monocarboxylic acid, it may be heated if necessary. Hereinafter, the description of the conductive particles shall include the surface-coated conductive particles.

The average particle size (D50) of the conductive particles is not particularly limited, but the conductive composition containing the conductive particles as the component (c) can be satisfactorily printed by various printing methods such as inkjet printing and screen printing. It is preferable to control the average particle size (D50) of the conductive particles. Specifically, the average particle size (D50) of the conductive particles is preferably 5 nm to 20 μm, more preferably 10 nm to 10 μm.
The average particle size (D50) of the conductive particles can be measured by a laser diffraction / scattering type particle size distribution measuring device (“Microtrack MT3000II” manufactured by Microtrac Bell Co., Ltd.).

The BET specific surface area of the conductive particles is preferably 0.05 to 400 m ² / g, more preferably 0.1 to 200 m ² / g.
The BET specific surface area of the conductive particles can be measured by the BET one-point method using a specific surface area measuring device (“Monosorb” manufactured by Yuasa Ionics Co., Ltd.).

The shape and aspect ratio (ratio of major axis to minor axis of particles) of conductive particles are not particularly limited, and are spherical, polyhedral, flat, plate-like, flake-like, flaky, rod-like, dendritic, fiber-like, etc. Various shapes can be used. As the conductive particles, one type selected from those having different constituents, average particle size, shape, aspect ratio, etc. may be used alone, or two or more types may be used in combination.
As the conductive particles, it is preferable to use one kind of conductive particles selected from spherical, flat, plate-like, flake-like, flaky-like, and dendritic-like, or two or more kinds of conductive particles, and it is preferable from the viewpoint of conductivity to use spherical particles. It is more preferable to use one kind of conductive particles selected from plate-like and dendritic-like ones or two kinds of conductive particles. When two types of conductive particles are used in combination, it is preferable to use spherical conductive particles and plate-shaped conductive particles.
When two types of spherical conductive particles and plate-shaped conductive particles are used in combination, the mass ratio is determined from the viewpoint of the conductivity of the cured film obtained by heating and curing the composition: spherical conductive particles: plate-shaped. The conductive particles of No. 1 are preferably 1:99 to 99: 1, more preferably 5:95 to 95: 5, and even more preferably 10:90 to 90:10.

The content of the component (c) is 60 to 95% by mass. The lower limit of the content of the component (c) is preferably 70% by mass, more preferably 80% by mass. The upper limit of the content of the component (c) is preferably 90% by mass.

[Component (d): Binder resin]
The component (d) used in the present invention is a binder resin, which is a component that acts as a binder in the conductive composition of the present invention.
As the component (d), a known binder resin used for a conductive paste or the like can be used, and examples thereof include a thermosetting resin, a photocurable resin, and a thermoplastic resin that are cured by heating or light irradiation. Can be done.

Examples of the thermosetting resin include epoxy resin, melamine resin, phenol resin, silicone resin, polyurethane resin, unsaturated polyester resin, vinyl ester resin, polyvinylphenol resin, xylene resin, acrylic resin, oxetane resin, diallyl phthalate resin and the like. Can be mentioned. Examples of the photocurable resin include acrylic resin, imide resin, urethane resin and the like. Examples of the thermoplastic resin include polyolefin resins such as polyamide, polyethylene terephthalate, and polyethylene; and acrylonitrile-butadiene-styrene copolymer resins.
As the binder resin of the component (d), one kind selected from these resins may be used alone, or two or more kinds may be used in combination.

Further, it is preferable to use one or more selected from the thermosetting resins such as epoxy resin, phenol resin, and polyvinylphenol resin from the viewpoint of curability, and one or two selected from epoxy resin and phenol resin. It is more preferable to use it.

The content of the component (d) is 1 to 30% by mass, preferably 3 to 25% by mass, more preferably 4 to 20% by mass, and further preferably 5 to 15% by mass. If the content of the component (d) is too small, it may be difficult to provide sufficient fluidity when printing with the conductive composition. If the content of the component (d) is too large, it may be difficult for the conductive particles of the component (c) to come into contact with each other in the conductive composition, and it may be difficult to obtain a cured film exhibiting excellent conductivity.

Further, the mass ratio when two kinds of epoxy resin and phenol resin are used in combination as the component (d) is preferably 1:99 to 99: 1 for epoxy resin: phenol resin from the viewpoint of curability. : 95 to 95: 5 is more preferable, and 10:90 to 90:10 is even more preferable.

[Other ingredients]
In addition to the above-mentioned components (a) to (d), the conductive composition of the present invention contains a solvent, a lubricant, a leveling agent, a dispersant, a curing agent, as needed, as long as the effects of the present invention are not impaired. It may contain various additives such as a curing accelerator, a plasticizer, a viscosity modifier, and a foaming agent. In addition, the conductive composition of the present invention may contain impurities that can be inevitably mixed from raw material components and devices in the manufacturing process.

(solvent)
The conductive composition of the present invention may contain a solvent for the purpose of improving the coatability and adjusting the viscosity.
Examples of the type of solvent include ether alcohols such as ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, and ethylene glycol monobutyl ether acetate; propylene glycol. , Non-ether alcohols such as 1,4-butanediol; esters such as cyclohexanol acetate, methylmethoxypropionate, ethylethoxypropionate, 1,6-hexanediol acetate; ketones such as isophorone and cyclohexanone. Terpenes such as tarpineol, dihydroterpineol, dihydroterpinyl acetate, isobornylcyclohexanol; other hydrocarbons such as octane, decane, dodecane, tetradecane, hexadecane, propylene carbonate and the like.
Among these solvents, it is preferable to use one or more kinds selected from the above ether alcohols, the above esters and the above terpenes, and more preferably one or more kinds selected from the terpenes. preferable.

The type of solvent is not limited to the above, and depending on the application, one selected from various solvents may be used alone, or two or more of them may be mixed and used. The mixing ratio when two or more kinds are mixed is not particularly limited.

When the conductive composition of the present invention contains a solvent, the content of the solvent is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the total content of the components (a) to (d). It is preferably 3 to 15 parts by mass, more preferably 4 to 10 parts by mass.

(Glidant)
In the conductive composition used in the present invention, a lubricant can be appropriately added for the purpose of adjusting the dispersibility of the conductive particles of the component (c) in the composition. The type of lubricant and the mixing ratio thereof are not particularly limited, and one type may be used alone or two or more types may be mixed depending on the intended use.
Types of lubricants include, for example, fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid; sodium, potassium, barium, magnesium, calcium, aluminum, iron, cobalt, manganese, zinc, tin, etc. Fatty acid metal salts formed from the metal and the fatty acids; fatty acid amides such as stearate amide, oleic acid amide, behenic acid amide, palmitate amide, lauric acid amide; fatty acid esters such as butyl stearate; paraffin wax , Waxes such as liquid paraffin; Alcohols such as ethylene glycol and stearyl alcohol; Polyethers composed of polyethylene glycol, polypropylene glycol and modified products thereof; Polysiloxanes such as silicone oil; Fluorine compounds such as fluorine-based oil Can be mentioned.
Among these lubricants, it is preferable to use one or more selected from fatty acids and fatty acid metal salts, and it is more preferable to use magnesium stearate.

When the conductive composition of the present invention contains a lubricant, the content of the lubricant is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the total content of the components (a) to (d). , More preferably 0.1 to 5 parts by mass, still more preferably 0.2 to 3 parts by mass.

(Leveling agent)
In the conductive composition used in the present invention, a leveling agent can be appropriately added for the purpose of adjusting the surface defects of the coating film obtained from the conductive composition. The type of leveling agent and the mixing ratio thereof are not particularly limited, and one type may be used alone or two or more types may be mixed depending on the intended use.
Examples of the type of leveling agent include BYK-354, BYK-355, BYK-356, BYK-350, BYK-381, BYK-394, BYK-399, BYK-3440, BYK-3441, BYK-358N, BYK. Acrylic compounds such as -361N (above, manufactured by Big Chemie Japan Co., Ltd., "BYK" is a registered trademark); Polyflow KL-400X, Polyflow KL-400HF, Polyflow KL-401, Polyflow KL-402, Polyflow KL- Silicone compounds such as 403, Polyflow KL-404, Polyflow KL-406X (all manufactured by Kyoeisha Chemical Co., Ltd.); Megafuck F410, Megafuck F281, Megafuck F477, Megafuck F510, Megafuck F552, Megafuck F554, Mega Fuck F556, Mega Fuck F557, Mega Fuck F558, Mega Fuck F559, Mega Fuck F560, Mega Fuck F561, Mega Fuck F563, Mega Fuck F569 (all manufactured by DIC Co., Ltd., "Mega Fuck" is a registered trademark). Fluorine compounds such as.
Among these leveling agents, it is preferable to use one or more selected from fluorine-based compounds, and it is more preferable to use Megafuck F477.

When the conductive composition of the present invention contains a leveling agent, the content of the leveling agent is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the total content of the components (a) to (d). It is more preferably 0.1 to 5 parts by mass, still more preferably 0.2 to 3 parts by mass.

(Dispersant)
In the conductive composition used in the present invention, a dispersant can be appropriately added for the purpose of adjusting the dispersibility of the conductive particles of the component (c) in the composition. The type of the dispersant and the mixing ratio thereof are not particularly limited, and one type may be used alone or two or more types may be mixed depending on the intended use.
Examples of the type of dispersant include sarcosine compounds such as lauroyl sarcosine, myritoyl sarcosin, palmitoyl sarcosin, stearoyl sarcosin, and oleoyl sarcosin; filanol PA-075F, philanol PA-085C, and filanol PA. High molecular weight amine compounds such as -107P, Esleam AD-3172M, Esleam AD-374M, Esleam AD-508E (all manufactured by Nichiyu Co., Ltd., "Esleam" is a registered trademark); Marialim AKM-0531, Marialim Examples include high molecular weight polycarboxylic acid compounds such as AFB-1521, Marialim AAB-0851, Marialim AWS-0851, Marialim SC-0505K, Marialim SC-1015F, and Marialim SC-0708A (all manufactured by Nichiyu Co., Ltd.). Be done.
Among these dispersants, it is preferable to use one or more selected from sarcosine compounds, and it is more preferable to use oleoyl sarcosine.

When the conductive composition of the present invention contains a dispersant, the content of the dispersant is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total content of the components (a) to (d). It is more preferably 0.2 to 5 parts by mass, still more preferably 0.3 to 3 parts by mass.

The production example and evaluation method of the conductive composition which concerns on this invention are shown below. Moreover, the embodiment of the present invention will be described more specifically with reference to Examples and Comparative Examples.
Each component used in Examples and Comparative Examples is shown below.
The physical characteristics of each component are values measured by the method described in the present specification.

[Component (a): Polyethylene glycol]
PEG200 (polyethylene glycol with an average molecular weight of 200)
PEG600 (polyethylene glycol with an average molecular weight of 600)
PEG2000 (polyethylene glycol with an average molecular weight of 2,000)
PEG4000 (polyethylene glycol with an average molecular weight of 4,000)
Glycerin

[Component (b): Aliphatic monocarboxylic acid]
2-Ethylhexanoic acid (branched saturated aliphatic monocarboxylic acid with 8 carbon atoms)
Lauric acid (a linear saturated aliphatic monocarboxylic acid having 12 carbon atoms)
Stearic acid (a linear saturated aliphatic monocarboxylic acid with 18 carbon atoms)

[Component (c): Conductive particles]
Copper particles (1): Spherical copper particles [Surface-coated copper particles (1), the production method is shown in Synthesis Example 1 below. ]
Copper particles (2): Dendrite copper particles [FCC-TB, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., particle size (D50): 5.5 to 8.0 μm]
Copper particles (3): Plate-shaped copper particles [Surface-coated copper particles (2), the production method is shown in Synthesis Example 2 below. ]

[Component (d): Binder resin]
Resol type phenol resin [PL-5208, manufactured by Gun Ei Chemical Industry Co., Ltd., solid content 60.0% by mass, solvent: diethylene glycol monoethyl ether]
Bisphenol F type epoxy resin [jER (registered trademark) -806, manufactured by Mitsubishi Chemical Corporation]

The following materials were used as other ingredients.
(Glidant)
Magnesium stearate (dispersant)
Ole oil sarcosin (leveling agent)
Fluorine compound [Megafuck (registered trademark) F-477, manufactured by DIC Corporation]
(solvent)
Tarpineol isovoronylcyclohexanol

[Synthesis Example 1]
(Copper particles (1): Production of surface-coated copper particles (1))
An ammonium chloride aqueous solution was prepared by dissolving 5 g of ammonium chloride in 100 g of water. Copper particles a [“1200Y” manufactured by Mitsui Metal Mining Co., Ltd .; particle size (D50) 2 μm, BET specific surface area 0.40 m ² / g, shape: spherical] 50 g were added to the ammonium chloride aqueous solution and subjected to nitrogen bubbling. , 30 ° C. for 60 minutes. The stirring was carried out using a mechanical stirrer at a rotation speed of 150 rpm. Hereinafter, stirring was performed at the same rotation speed using the same stirring device. After the stirring was completed, the copper particles were filtered off by vacuum filtration using a Kiriyama funnel of 5C filter paper, and subsequently, the copper particles were washed twice with 150 g of water on the Kiriyama funnel.
The washed copper particles were added to 250 g of a 40% by mass diethylenetriamine aqueous solution, and the mixture was heated and stirred at 60 ° C. for 1 hour while nitrogen bubbling.

After the stirring was stopped and the mixture was allowed to stand for 5 minutes, about 200 g of the supernatant liquid was withdrawn and removed. Subsequently, 200 g of isopropanol was added to the precipitate as a cleaning solvent, and the mixture was stirred at 30 ° C. for 3 minutes. After stopping the stirring and allowing to stand for 5 minutes, about 200 g of the supernatant liquid was withdrawn and removed, and then 250 g of 2% by mass isopropanol laurate solution was added, and then the mixture was stirred at 30 ° C. for 30 minutes.
After the stirring was completed, the copper particles were filtered off by vacuum filtration using a Kiriyama funnel of 5C filter paper. The obtained copper particles were dried under reduced pressure at 25 ° C. for 3 hours to obtain surface-coated copper particles (1) (copper particles (1)).

[Synthesis Example 2]
(Copper particles (3): Production of surface-coated copper particles (2))
Synthesis Example 1 except that the copper particles a were changed to copper particles b [“1400YP” manufactured by Mitsui Metal Mining Co., Ltd .; particle size (D50) 6 μm, BET specific surface area 0.60 m ² / g, shape: plate shape]. In the same manner, surface-coated copper particles (2) (copper particles (3)) were obtained.

[Example 1]
(Manufacturing of conductive composition)
1.5 g of PEG200 as the component (a), 1.5 g of lauric acid as the component (b), 87 g of the surface-coated copper particles (1) (copper particles (1)) as the component (c), and the component (d). 16.7 g (10 g as a solid content) of a resole-type phenol resin [PL-5208, manufactured by Gunei Chemical Industry Co., Ltd., solid content 60% by mass, solvent: diethylene glycol monoethyl ether] was mixed. Next, using a planetary mixer [ARV-310, manufactured by Shinky Co., Ltd.], the mixture was stirred at a rotation speed of 1500 rpm for 60 seconds at room temperature to perform primary kneading.
Next, secondary kneading was carried out by passing through a three-roll mill [EXAKT-M80S, manufactured by Nagase Screen Printing Laboratory Co., Ltd.] 5 times under the conditions of room temperature and a distance between rolls of 5 μm. 8 g of tarpineol (Ter) is added to the kneaded product obtained by the secondary kneading, and the mixture is stirred at room temperature and vacuum conditions at a rotation speed of 1000 rpm for 90 seconds using a planetary mixer to defoam and knead the conductive composition. Manufactured a thing.
Table 1 shows the blending ratio of each component in the conductive composition.

(Formation of cured film)
The obtained conductive composition was coated on a glass substrate with a pattern of width × length × thickness = 1.0 mm × 30 mm × 50 μm using a metal mask. A cured film was prepared by heating a glass substrate coated with the conductive composition in a convection oven at 250 ° C. for 30 minutes in an atmospheric atmosphere.

(Evaluation method of resistance value)
The conductivity of the cured film obtained by the above method was evaluated by the following resistance value measurement. A measuring probe was pressed against both ends of the formed pattern, and the resistance value of the cured film was measured using a digital multimeter [PC7000, manufactured by Sanwa Electric Instrument Co., Ltd.], and the resistance value was determined according to the following evaluation criteria.
The lower the resistance value of the cured film, the easier it is for current to flow, indicating that the conductivity is excellent.
⊚: The resistance value is less than 1.0Ω.
◯: The resistance value is 1.0 Ω or more and less than 10.0 Ω.
Δ: The resistance value is 10.0 Ω or more and less than 50.0 Ω.
X: The resistance value is 50.0Ω or more.

(Evaluation method of viscosity change rate before and after continuous printing)
The obtained conductive composition was continuously printed on a PET film using a screen printing machine [MT-320T, manufactured by Microtech Co., Ltd.].
Using an E-type viscometer [TV-25, manufactured by Toki Sangyo Co., Ltd.], measure the viscosity of each conductive composition before and after continuous printing using a screen printing machine, and determine the viscosity change rate. It was calculated by the following formula (I) and judged by the following evaluation criteria.
In this test, it is shown that the smaller the value of the viscosity change rate is, the less the viscosity of the conductive composition is changed during continuous printing, and the more stable the printability is.

Viscosity change rate (%) =
[(Viscosity of the conductive composition after the continuous printing test) / (Viscosity of the conductive composition before the continuous printing test)] × 100 ... (I)
⊚: The viscosity change rate is less than 110%.
◯: The viscosity change rate is 110% or more and less than 150%.
Δ: The viscosity change rate is 150% or more and less than 200%.
X: The viscosity change rate is 200% or more.

(Evaluation method of line width maintenance rate before and after intermittent printing)
After printing one sheet of the obtained conductive composition on a PET film using a screen printing machine [MT-320T, manufactured by Microtech Co., Ltd.], the conductive composition is allowed to stand on a screen plate for 60 minutes. After placing it, one sheet was printed on another PET film.
The line width before and after printing was measured using a laser microscope [VK-9700, manufactured by KEYENCE CORPORATION], the line width maintenance rate was calculated by the following formula (II), and the judgment was made according to the following evaluation criteria. ..
In this test, it is shown that the closer the line width retention rate value is to 100%, the longer the wettability of the conductive composition is maintained during intermittent printing, and the more stable the wiring pattern can be printed.

Line width maintenance rate (%) =
[(Line width of wiring pattern printed after standing for 60 minutes) / (Line width of wiring pattern printed on the first sheet)] × 100 ... (II)
⊚: The line width maintenance rate is 90% or more and 100% or less.
◯: The line width maintenance rate is 70% or more and less than 90%.
Δ: The line width maintenance rate is 50% or more and less than 70%.
X: The line width maintenance rate is less than 50%.

[Examples 2 to 11: Comparative Examples 1 to 4]
The conductive composition was produced and applied to a glass substrate using a metal mask in the same manner as in Example 1 except that the blending ratio of each component was as shown in Tables 1 to 3. Regarding the formation of the cured film, Examples 2 to 6 and 8 to 10 and Comparative Examples 1 to 4 were heated in an atmospheric atmosphere, and Examples 7 and 11 were heated in a nitrogen atmosphere.
Further, for each cured film, the resistance value, the viscosity change rate before and after continuous printing, and the line width maintenance rate before and after intermittent printing were evaluated in the same manner as in Example 1. The results of Examples 1 to 6 are shown in Table 1, the results of Examples 7 to 11 are shown in Table 2, and the results of Comparative Examples 1 to 4 are shown in Table 3. The content of the phenol resin in Tables 1 to 3 is a solid content conversion amount.

In Examples 1 to 11, the resistance values of the cured films are all less than 10.0Ω, the viscosity change rate before and after continuous printing is less than 150%, and the line width maintenance rate before and after intermittent printing is 70% or more. ..
On the other hand, in Comparative Example 1 in which the conductive composition was prepared without blending the component (a), the resistance value of the cured film was as high as 10.0 Ω or more, and the viscosity change rate before and after continuous printing was 200% or more. The line width maintenance rate before and after intermittent printing was as low as less than 70%.
Further, in Comparative Example 2 in which the conductive composition was prepared without blending the component (b), the line width retention rate before and after intermittent printing was 70%, but the resistance value of the cured film was 50.0 Ω or more. It was high, and the rate of change in viscosity before and after continuous printing was as high as 200% or more.
In Comparative Example 3 in which the conductive composition was prepared using PEG4000 instead of the component (a), the resistance value of the cured film was less than 10.0Ω, but the viscosity change rate before and after continuous printing was 200% or more. It was high, and the line width maintenance rate before and after intermittent printing was as low as less than 50%.
Further, in Comparative Example 4 in which the conductive composition was prepared by using glycerin instead of the component (a), the resistance value of the cured film was as high as 85Ω.

[Example 12]
With the following composition, the conductive composition was produced and the cured film was formed in the same manner as in Example 1. Further, for each cured film, the resistance value, the viscosity change rate before and after continuous printing, and the line width maintenance rate before and after intermittent printing were evaluated in the same manner as in Example 1.

Ingredient (a): PEG200 1.5g
Ingredient (b): Lauric acid 1.5 g
Component (c) Conductive particles: Surface-coated copper particles (copper particles (1)) 87 g
Ingredient (d) Binder resin: Resol type phenol resin 16.7 g (10 g as solid content)
Lubricants: Magnesium stearate 0.3g
Leveling agent: Megafuck F-477 0.3g
Solvent: Tarpineol 8g

The evaluation was "○" because the resistance value of the cured film was 2.5Ω, the evaluation was "◎" because the viscosity change rate before and after continuous printing was 105%, and the line width maintenance rate before and after intermittent printing was Since it was 85%, the evaluation was judged to be "○".

[Example 13]
With the following composition, the conductive composition was produced and the cured film was formed in the same manner as in Example 1. Further, for each cured film, the resistance value, the viscosity change rate before and after continuous printing, and the line width maintenance rate before and after intermittent printing were evaluated in the same manner as in Example 1.

Ingredient (a): PEG600 1.5g
Ingredient (b): Lauric acid 1.5 g
Component (c) Conductive particles: Surface-coated copper particles (copper particles (1)) 87 g
Ingredient (d) Binder resin: Resol type phenol resin 10 g (6 g as solid content), bisphenol F type epoxy resin 4 g
Dispersant: Oleoil Zarcosin 1g
Solvent: Tarpineol 2g, Isoborolcyclohexanol 6g

The evaluation was "○" because the resistance value of the cured film was 1.2Ω, the evaluation was "◎" because the viscosity change rate before and after continuous printing was 105%, and the line width maintenance rate before and after intermittent printing was Since it was 95%, it was judged as "◎".

Claims (1)

(A) Polyethylene glycol having an average molecular weight of 200 to 2,000 in an amount of 0.1 to 5% by mass,
(B) 0.1 to 5% by mass of an aliphatic monocarboxylic acid having 8 to 18 carbon atoms.
(C) A conductive composition containing 60 to 95% by mass of conductive particles and (d) 1 to 30% by mass of a binder resin.