CN114093551A

CN114093551A - Conductive composition

Info

Publication number: CN114093551A
Application number: CN202110938015.2A
Authority: CN
Inventors: 久保田和宏; 田上安宣
Original assignee: NOF Corp
Current assignee: NOF Corp
Priority date: 2020-08-24
Filing date: 2021-08-16
Publication date: 2022-02-25
Also published as: TW202219986A; JP2022036917A; KR20220025669A

Abstract

The invention provides a conductive composition, which is difficult to change the line width of a wiring pattern and the viscosity of the composition before and after restarting printing when restarting printing after stopping printing for a certain time, and has excellent printing performance and conductivity. The conductive composition contains: 0.1 to 5 mass% of (a) polyethylene glycol having an average molecular weight of 200 to 2,000, (b) aliphatic monocarboxylic acid having 8 to 18 carbon atoms, (c) conductive particles, and (d) binder resin, 0.1 to 5 mass% of (b) the conductive particles, and (c) 1 to 30 mass% of (d).

Description

Conductive composition

Technical Field

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

Background

In recent years, due to increased awareness of safety and environmental issues, it has been required to reduce the amount of chemical solutions that affect the human body and the environment. In a wiring formation method for an electronic device, a conventional wet etching method using a large amount of chemical solution is replaced with a printing method using a small amount of chemical solution. Among them, as a general printing method, development of a wiring forming technique using a screen printer is actively carried out, and as a material thereof, research and development of a conductive paste suitable for screen printing are also advanced. The conductive paste is required to have various characteristics necessary for developing a target product, such as conductivity and adhesion to a substrate to which the conductive paste is applied. Among these, a particularly strongly required characteristic from the viewpoint of productivity is printability, and a conductive paste having excellent printability is strongly required. For example, patent document 1 discloses a conductive paste which is excellent in fine line printability and hardly changes in print line width.

In the formation of wiring by screen printing, a conductive paste capable of continuously printing wiring patterns of the same line width for a long time is preferable from the viewpoint of productivity. However, in an actual manufacturing process, printing is frequently stopped for a long time due to operational concerns such as checking a printed pattern or a dot printer. For example, when screen printing is performed using the conductive paste of patent document 1, when printing is stopped for a certain time and then printing is started again, there is a problem as follows: the conductive paste is dried on the screen plate to cause mesh blockage; thickening due to volatilization of the solvent in the conductive paste causes defects such as blooming (カスレ) to occur in the wiring pattern after the printing is restarted, or the line width of the wiring pattern changes greatly before and after the printing is restarted.

That is, when the screen printing is stopped for a certain time by using the conductive paste, depending on the length of the stop time, there is a possibility that the resistance value increases due to the variation in the line width of the wiring pattern or the wire may be broken due to the white scattering.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2014-67492

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a conductive composition which, when printing is resumed after printing is stopped for a certain period of time, is less likely to change the line width of a wiring pattern and the viscosity of the composition before and after resuming printing, and has excellent printability and conductivity.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that a conductive composition capable of solving the above-mentioned problems can be provided by blending a specific component having excellent dispersion stability of conductive particles and a specific component capable of maintaining a wet state of the composition for a long time in addition to the conductive particles and the binder resin, and have completed the present invention.

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

Effects of the invention

According to the conductive composition of the present invention, it is possible to obtain an effect that the line width of a wiring pattern and the viscosity of the composition are not easily changed before and after resuming printing when resuming printing after stopping printing for a certain time, while being useful as a wiring forming material excellent in conductivity and printability. Therefore, a wiring pattern which is less likely to cause an increase in resistance value and disconnection can be printed.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

In the present specification, the numerical range defined by the symbols "to" includes the numerical values at both ends (upper limit and lower limit) of the "to". For example, "2 to 5" means 2 or more and 5 or less.

Further, where concentrations or amounts are specified, any higher concentration or amount can be associated with any lower concentration or amount. For example, when there are descriptions of "2 to 10% by mass" and "preferably 4 to 8% by mass", the descriptions also include descriptions of "2 to 4% by mass", "2 to 8% by mass", "4 to 10% by mass", and "8 to 10% by mass".

The conductive composition of the present invention contains: (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) a binder resin. Hereinafter, each component will be described.

The content of each of the components (a), (b), (c), and (d) is a ratio (% by mass) to the total of the contents of the components (a), (b), (c), and (d).

[ component (a): polyethylene glycol

The component (a) used in the present invention is polyethylene glycol having an average molecular weight of 200 to 2,000, preferably 400 to 1,500, more preferably 500 to 800, from the viewpoint of maintaining wettability. These polyethylene glycols may be used singly 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 from 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 the wettability, the amount of the surfactant is preferably 0.2 to 5% by mass, more preferably 0.3 to 5% by mass, and still more 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 still more preferably 0.1 to 2% by mass.

If the content of the component (a) is too small, it is difficult to exhibit good wettability and to maintain wettability for a long time, and therefore the line width of the wiring pattern may easily change before and after resuming printing. If the content of the component (a) is too large, the conductivity of the conductive composition may be reduced.

[ component (b): aliphatic monocarboxylic acids

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 linear saturated aliphatic monocarboxylic acids, linear unsaturated aliphatic monocarboxylic acids, branched saturated aliphatic monocarboxylic acids, and branched unsaturated aliphatic monocarboxylic acids. One kind selected from the above-mentioned compounds may be used alone, or two or more kinds selected from the above-mentioned compounds may be used simultaneously.

Examples of the linear saturated aliphatic monocarboxylic acid having 8 to 18 carbon atoms include octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid. 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 and the like.

The component (b) is preferably a linear saturated aliphatic monocarboxylic acid having 8 to 18 carbon atoms from the viewpoint of electrical conductivity. 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 viscosity change, the amount is preferably 0.3 to 5% by mass, more preferably 0.5 to 5% by mass, and still more 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 still more preferably 0.1 to 3% by mass.

If the content of the component (b) is too small, the viscosity of the conductive composition may be easily increased. When the content of the component (b) is too large, the conductivity of the conductive composition may be lowered.

[ 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 formed of copper alone, or may further contain a metal other than copper, such as silver or platinum, a metal oxide, or a metal sulfide. When the copper particles further contain a metal other than copper, a metal oxide, or a metal sulfide, the mass ratio of copper in the copper particles is preferably 50 mass% or more. Further, the copper particles may have a shape in which a surface layer or projections are formed.

As the conductive particles, commercially available products can be used as they are, but surface-coated conductive particles whose surfaces are coated for the purpose of improving oxidation resistance and the like are preferably used. Among them, the surface-coated conductive particles whose surfaces are coated with the amine compound are preferably used, and more preferably, the surface-coated conductive particles whose surfaces are coated with the amine compound represented by the following formula (1).

[ chemical formula 1]

In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, m is any one of 0 to 3 when n is 0, and m is any one of 1 to 3 when n is 1 or 2.

From the viewpoint of obtaining more excellent oxidation resistance, the surface-coated conductive particles whose surfaces are coated with an amine compound such as the amine compound represented by the above formula (1) are preferably surface-coated conductive particles further coated with an aliphatic monocarboxylic acid.

Thus, the surface of the conductive particle is covered with the first covering layer made of the amine compound and the second covering layer made of the aliphatic monocarboxylic acid. Preferably, the first cover layer is formed on the surface of the conductive particle, and the second cover layer is formed on the first cover layer.

The aliphatic monocarboxylic acid forming the second cover layer is preferably an aliphatic monocarboxylic acid having 8 to 20 carbon atoms. Examples of the aliphatic monocarboxylic acid include linear saturated aliphatic monocarboxylic acids, linear unsaturated aliphatic monocarboxylic acids, branched saturated aliphatic monocarboxylic acids, and branched unsaturated aliphatic monocarboxylic acids.

Examples of the linear saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, and eicosanoic acid. 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 and the like.

The aliphatic monocarboxylic acid may be used alone or in combination of two or more selected from the above compounds.

From the viewpoint of dispersibility of the surface-coated conductive particles, it is preferable to use an aliphatic monocarboxylic acid having the same or similar structure and carbon number as 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 surfaces are coated with an amine compound, for example, there is a method in which conductive particles are washed with an aqueous ammonium chloride solution or the like, and then the washed conductive particles are added to a solution of the amine compound, and heated as necessary.

As a method for producing the surface-coated conductive particles covered with the first covering layer formed of the amine compound and the second covering layer formed of the aliphatic monocarboxylic acid, for example, a method in which surface-coated conductive particles whose surfaces are covered with the amine compound are added to a solution of the aliphatic monocarboxylic acid can be cited. In addition, heating may be performed after addition to the solution of the aliphatic monocarboxylic acid as necessary. Hereinafter, the description of the conductive particles includes surface-coated conductive particles.

The average particle diameter (D50) of the conductive particles is not particularly limited, but the average particle diameter (D50) of the conductive particles is preferably controlled so that a conductive composition containing the conductive particles as the component (c) can be printed well by various printing methods such as inkjet printing and screen printing. Specifically, the average particle diameter (D50) of the conductive particles is preferably 5nm to 20 μm, and more preferably 10nm to 10 μm.

The average particle diameter (D50) of the conductive particles can be measured by a laser diffraction/scattering particle size distribution analyzer ("Microtrac MT3000 II" manufactured by Microtrac bell corp.

Furthermore, the BET specific surface area of the conductive particles is preferably 0.05 to 400m²A more preferable range is 0.1 to 200 m/g²/g。

The BET specific surface area of the conductive particles can be measured by a BET single-point method using a BET specific surface area measuring apparatus ("MONOSORB" manufactured by ユアサアイオニクス ltd.).

The shape and aspect ratio of the conductive particles (ratio of the major axis to the minor axis of the particles) are not particularly limited, and conductive particles having various shapes such as spherical, polyhedral, flat, plate-like, scaly, flaky, rod-like, dendritic, and fibrous shapes can be used. The conductive particles may be used singly or in combination of two or more kinds selected from among conductive particles having different constituent components, average particle diameters, shapes, aspect ratios, and the like.

From the viewpoint of conductivity, the conductive particles are preferably one or more selected from spherical, flat, plate-like, scaly, flaky, and dendritic conductive particles, and more preferably one or more selected from spherical, plate-like, and dendritic conductive particles. When two kinds of conductive particles are used simultaneously, spherical conductive particles and plate-like conductive particles are preferably used.

From the viewpoint of the conductivity of the cured film obtained by heat curing the composition, the mass ratio of the spherical conductive particles to the plate-like conductive particles when both of the spherical conductive particles and the plate-like conductive particles are used is preferably 1:99 to 99:1, more preferably 5:95 to 95:5, and still more preferably 10:90 to 90: 10.

The content of the component (c) is 60 to 95% by mass, and the lower limit of the content of the component (c) is preferably 70% by mass, and 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 functions 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, a thermoplastic resin, and the like which are cured by heating or light irradiation.

Examples of the thermosetting resin include epoxy resin, melamine resin, phenol resin, silicone resin, polyurethane resin (polyurethane resin), unsaturated polyester resin, vinyl ester resin, polyvinyl phenol resin, xylene resin, acrylic resin, oxetane resin, and diallyl phthalate resin. Examples of the photocurable resin include acrylic resins, imide resins, urethane resins (urethane resins), and the like. Examples of the thermoplastic resin include polyolefin resins such as polyamide, polyethylene terephthalate, and polyethylene; acrylonitrile-butadiene-styrene copolymer resins, and the like.

As the binder resin of the component (d), one selected from the above resins may be used alone, or two or more selected from the above resins may be used simultaneously.

In addition, from the viewpoint of curability, one or more selected from the group consisting of epoxy resins, phenol resins, and polyvinyl phenol resins are preferably used as the thermosetting resin, and one or two selected from the group consisting of epoxy resins and phenol resins are more preferably used.

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 become difficult to maintain sufficient fluidity when printing is performed using the conductive composition. If the content of the component (d) is too large, the conductive particles of the component (c) in the conductive composition are difficult to contact with each other, and it may be difficult to obtain a cured film exhibiting excellent conductivity.

In addition, from the viewpoint of curability, the mass ratio of the epoxy resin to the phenol resin when the epoxy resin and the phenol resin are used together as the component (d) is preferably 1:99 to 99:1, more preferably 5:95 to 95:5, and still more preferably 10:90 to 90: 10.

[ other ingredients ]

The conductive composition of the present invention may contain, in addition to the above-mentioned components (a) to (d), various additives such as a solvent, a lubricant, a leveling agent, a dispersant, a curing agent, a curing accelerator, a plasticizer, a viscosity modifier, and a foaming agent as necessary within a range in which the effects of the present invention are not impaired. The conductive composition of the present invention may further contain impurities which may be inevitably mixed in, for example, raw material components and apparatuses in the production process.

(solvent)

The conductive composition of the present invention may contain a solvent for the purpose of improving coatability or adjusting viscosity.

Examples of the type of the solvent include ether alcohols such as ethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, and ethylene glycol monobutyl ether acetate; non-ether alcohols such as propylene glycol and 1, 4-butanediol; esters such as cyclohexanol acetate, methyl methoxypropionate, ethyl ethoxypropionate, and 1, 6-hexanediol acetate; ketones such as isophorone and cyclohexanone; terpenes such as terpineol, dihydroterpineol, dihydroabienol acetate, isobornyl cyclohexanol (isobornyl cyclohexanol); and other hydrocarbons such as octane, decane, dodecane, tetradecane, hexadecane, and propylene carbonate.

Among the solvents, one or more selected from the ether alcohols, the esters, and the terpenes are preferably used, and more preferably one or more selected from the terpenes are used.

The kind of the solvent is not limited to the above-mentioned ones, and one selected from various solvents may be used alone or two or more selected from various solvents may be used in combination according to the use. When two or more kinds are mixed, the mixing ratio 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, more preferably 3 to 15 parts by mass, and still more preferably 4 to 10 parts by mass, based on 100 parts by mass of the total content of the components (a) to (d).

(Lubricant)

The conductive composition used in the present invention may be appropriately added with a lubricant for the purpose of adjusting the dispersibility of the conductive particles of the component (c) in the composition. The kind of the lubricant and the mixing ratio thereof are not particularly limited, and one kind or two or more kinds may be used in combination according to the use.

Examples of the type of lubricant include fatty acids such as dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, and docosanoic acid; fatty acid metal salts formed from a metal such as sodium, potassium, barium, magnesium, calcium, aluminum, iron, cobalt, manganese, zinc, tin, and the like, and the fatty acid; fatty acid amides such as stearic acid amide, oleic acid amide, behenic acid amide, palmitic acid amide and lauric acid amide; fatty acid esters such as butyl stearate; waxes such as paraffin (paraffin wax) and liquid paraffin (liquid paraffin); alcohols such as ethylene glycol and stearyl alcohol; polyethers formed from polyethylene glycol, polypropylene glycol, and modifications thereof; polysiloxanes such as silicone oil; fluorine compounds such as fluorine oils.

Among the above lubricants, one or two or more selected from fatty acids and fatty acid metal salts are preferably used, and magnesium stearate is more preferably used.

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, more preferably 0.1 to 5 parts by mass, and still more preferably 0.2 to 3 parts by mass, based on 100 parts by mass of the total content of the components (a) to (d).

(leveling agent)

The conductive composition used in the present invention may be added with a leveling agent as appropriate for the purpose of adjusting surface defects of a coating film obtained from the conductive composition. The kind of the leveling agent and the mixing ratio thereof are not particularly limited, and one kind may be used alone or two or more kinds may be used in combination according to the use.

Examples of the type of the leveling agent include acrylic compounds such as BYK-354, BYK-355, BYK-356, BYK-350, BYK-381, BYK-394, BYK-399, BYK-3440, BYK-3441, and BYK-358N, BYK-361N (which is manufactured by BYK Japan KK., and "BYK" is a registered trademark); silicone compounds such as POLYFLOW KL-400X, POLYFLOW KL-400HF, POLYFLOW KL-401, POLYFLOW KL-402, POLYFLOW KL-403, POLYFLOW KL-404, POLYFLOW KL-406X (KYOEISYA CHEMICAL Co., LTD.); MEGAFACE F410, MEGAFACE F281, MEGAFACE F477, MEGAFACE F510, MEGAFACE F552, MEGAFACE F554, MEGAFACE F556, MEGAFACE F557, MEGAFACE F558, MEGAFACE F559, MEGAFACE F560, MEGAFACE F561, MEGAFACE F563, and MEGAFACE F569 (manufactured by DIC CORPORATION, "MEGAFACE" is a registered trademark), and other fluorine-based compounds.

In the leveling agent, one or two or more selected from fluorine compounds are preferably used, and MEGAFACE F477 is more preferably used.

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, more preferably 0.1 to 5 parts by mass, and still more preferably 0.2 to 3 parts by mass, based on 100 parts by mass of the total content of the components (a) to (d).

(dispersing agent)

The conductive composition used in the present invention may be appropriately added with a dispersant for the purpose of adjusting the dispersibility of the conductive particles of the component (c) in the composition. The kind of the dispersant and the mixing ratio thereof are not particularly limited, and one kind or two or more kinds may be used in combination according to the use.

Examples of the type of the dispersant include sarcosine compounds such as lauroyl sarcosine, myristoyl sarcosine, palmitoyl sarcosine, stearoyl sarcosine, and oleoyl sarcosine; high molecular amine compounds such as Filllanol PA-075F, Filllanol PA-085C, Filllanol PA-107P, ESLEAM AD-3172M, ESLEAM AD-374M, and ESLEAM AD-508E (made by NOF CORPORATION, ESLEAM is registered trademark); MALIALIM AKM-0531, MALIALIIM AFB-1521, MALIALIIM AAB-0851, MALIALIM AWS-0851, MALIALIM SC-0505K, MALIALIM SC-1015F, MALIALIM SC-0708A (made by NOF CORPORATION above) and other high molecular weight polycarboxylic acid compounds.

Among the above dispersants, one or two or more selected from the group of sarcosine compounds are preferably used, and oleoyl sarcosine is more preferably used.

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, more preferably 0.2 to 5 parts by mass, and still more preferably 0.3 to 3 parts by mass, based on 100 parts by mass of the total content of the components (a) to (d).

Examples

The following are examples of production and evaluation methods of the conductive composition of the present invention. The embodiments of the present invention will be further specifically described with reference to examples and comparative examples.

The components used in the examples and comparative examples are shown below.

The physical properties of each component are values measured by the methods described in the present specification.

[ component (a): polyethylene glycol

PEG200 (polyethylene glycol with average molecular weight of 200)

PEG600 (polyethylene glycol with average molecular weight of 600)

PEG2000 (polyethylene glycol having an average molecular weight of 2,000)

PEG4000 (polyethylene glycol having an average molecular weight of 4,000)

Glycerol

[ component (b): aliphatic monocarboxylic acids

2-Ethylhexanoic acid (C8 branched saturated aliphatic monocarboxylic acid)

Dodecanoic acid (C12 linear saturated aliphatic monocarboxylic acid)

Octadecanoic acid (C18 linear saturated aliphatic monocarboxylic acid)

[ component (c): conductive particles

Copper particles (1): the spherical copper particles [ surface-coated copper particles (1) ] were produced by the method described in synthetic example 1 below. ]

Copper particles (2): dendritic copper particles [ FCC-TB, FUKUDA METAL FOIL & POWDER co., ltd., manufactured, particle size (D50): 5.5 to 8.0 μm ]

Copper particles (3): the plate-like copper particles [ surface-coated copper particles (2) ] were produced by the method described in synthesis example 2 below. ]

[ component (d): binder resin

Phenol resin of resol type (resol) phenol resin [ PL-5208, manufactured by Gunei Chemical Industry co., ltd., 60.0 mass% solid content, solvent: diethylene glycol monoethyl ether ]

Bisphenol F type epoxy resin [ jER (registered trademark) -806, manufactured by Mitsubishi Chemical Corporation ]

As other components, the following materials were used.

(Lubricant)

Magnesium stearate

(dispersing agent)

Oleoyl sarcosine

(leveling agent)

Fluorine-containing Compound [ MEGAFACE (registered trademark) F-477, manufactured by DIC CORPORATION ]

(solvent)

Terpineol

Isobornyl cyclohexanol

[ Synthesis example 1]

(production of copper particles (1): surface-coated copper particles (1))

An aqueous ammonium chloride solution in which 5g of ammonium chloride was dissolved in 100g of water was prepared. 50g of copper particles a [ MITSUI MINING ]&"1200Y" manufactured by smeling co., ltd; the particle diameter (D50) was 2 μm, and the BET specific surface area was 0.40m²,/g, shape: spherical shape]The mixture was added to the aqueous ammonium chloride solution, and stirred at 30 ℃ for 60 minutes under nitrogen bubbling. Stirring was carried out at a rotational speed of 150rpm using a mechanical stirrer. Hereinafter, the same stirring apparatus was used and the stirring was performed at the same rotation speed. After the stirring was completed, filtration was performed under reduced pressure using a Tung mountain funnel of 5C filter paper to filter out copper particles, and then the copper particles were washed twice on the Tung mountain funnel with 150g of water.

The washed copper particles were added to 250g of a 40 mass% aqueous solution of diethylenetriamine, and the mixture was heated and stirred at 60 ℃ for 1 hour while bubbling nitrogen gas.

The stirring was stopped, and after standing for 5 minutes, about 200g of the supernatant was removed by suction. Then, 200g of isopropyl alcohol as a solvent for washing was added to the precipitate, and stirring was performed at 30 ℃ for 3 minutes. The stirring was stopped, and after standing for 5 minutes, about 200g of the supernatant was removed by suction, and then after adding 250g of a 2 mass% dodecanoic acid isopropanol solution, stirring was carried out at 30 ℃ for 30 minutes.

After completion of the stirring, the mixture was filtered under reduced pressure using a Tung mountain funnel with 5C filter paper to filter out copper particles. The obtained copper particles were dried under reduced pressure at 25 ℃ for 3 hours, thereby obtaining surface-coated copper particles (1) (copper particles (1)).

[ Synthesis example 2]

(production of copper particles (3): surface-coated copper particles (2))

Except that the copper particles a are changed to copper particles b [ MITSUI MINING&SMELTING CO., LTD. "1400 YP", particle size (D50) of 6 μm and BET specific surface area of 0.60m²,/g, shape: plate-like shape]Except that, surface-coated copper particles (2) (copper particles (3)) were obtained in the same manner as in synthesis example 1.

[ example 1]

(preparation of electroconductive composition)

1.5g of PEG200 as component (a), 1.5g of dodecanoic acid as component (b), 87g of surface-coated copper particles (1) (copper particles (1)) as component (c), and 16.7g (10 g of solid content) of resol type phenolic resin [ PL-5208, manufactured by Gunei Chemical Industry co., ltd., 60 mass% of solid content, solvent: diethylene glycol monoethyl ether. Then, a planetary mixer [ ARV-310, manufactured by THINKY CORPORATION ] was used to perform primary kneading at room temperature at 1500rpm for 60 seconds.

Then, a three-roll mill [ EXAKT-M80S, manufactured by Nagase Screen Printing Research Co., Ltd ] was used to perform secondary kneading by passing 5 times at room temperature with an inter-roll distance of 5 μ M. To the kneaded product obtained by the secondary kneading, 8g of terpineol (Ter) was added, and the mixture was stirred for 90 seconds at 1000rpm under vacuum conditions at room temperature using a planetary stirrer, and defoaming kneading was performed, thereby preparing a conductive composition.

The blending ratio of each component in the conductive composition is shown in table 1.

(formation of cured film)

The obtained conductive composition was applied to a glass substrate using a metal mask in a pattern of 1.0mm by 30mm by 50 μm in width by length by thickness. The glass substrate coated with the conductive composition was heated at 250 ℃ for 30 minutes in an atmospheric atmosphere using a convection oven, thereby producing a cured film.

(method of evaluating resistance value)

The cured film obtained by the above method was evaluated for conductivity by the following resistance value measurement. The resistance value of the cured film was measured using a digital multimeter [ PC7000, Sanwa Electric Instrument co., ltd. ] with measurement probes pressed against both ends of the formed pattern, and the determination was made according to the following evaluation criteria.

The lower the resistance value of the cured film, the more easily the current flows, and the more excellent the conductivity.

Very good: the resistance value is less than 1.0 omega.

O: the resistance value is 1.0 omega or more and less than 10.0 omega.

And (delta): the resistance value is 10.0 Ω or more and less than 50.0 Ω.

X: the resistance value is 50.0 omega or more.

(evaluation method of viscosity Change Rate before and after continuous printing)

The resulting conductive composition was printed on a PET film using a screen printer [ MT-320T, Micro-tec co., ltd.

The viscosity of the conductive composition before and after continuous printing using a screen printer was measured using an E-type viscometer [ TV-25, TOKI SANGYO co., ltd. ], and the viscosity change rate was determined by the following formula (I) and determined based on the following evaluation criteria.

In this test, the smaller the value of the viscosity change rate, the less the viscosity of the conductive composition is changed during continuous printing, and the more stable the printability.

Viscosity change rate (%) [ (viscosity of conductive composition after continuous printing test)/(viscosity of conductive composition before continuous printing test) ] × 100 … (I)

Very good: the viscosity change rate is less than 110%.

O: the viscosity change rate is more than 110% and less than 150%.

And (delta): the viscosity change rate is more than 150% and less than 200%.

X: the viscosity change rate is more than 200%.

(evaluation method of line Width maintenance ratio before and after intermittent printing)

After the obtained conductive composition was printed on a PET film for 1 sheet using a screen printer [ MT-320T, Micro-tec co., ltd., manufactured ], the conductive composition was left to stand on a screen plate for 60 minutes, and then it was printed on another PET film for 1 sheet.

The line widths before and after printing were measured using a laser microscope [ VK-9700, manufactured by Keyence Corporation ], and the line width maintenance ratio was determined by the following formula (II). The judgment was made according to the following evaluation criteria.

In this test, the closer the value of the line width maintenance ratio is to 100%, the more the wettability of the conductive composition can be maintained for a long period of time in the intermittent printing, and the more the wiring pattern can be printed stably.

Line width maintenance ratio (%) [ (line width of printed wiring pattern after standing for 60 minutes)/(line width of wiring pattern at the time of printing first sheet) ] × 100 … (II)

Very good: the line width maintenance rate is 90% or more and 100% or less.

O: the line width maintenance rate is 70% or more and less than 90%.

And (delta): 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 preparation of the conductive composition and the coating on the glass substrate using the metal mask were carried out in the same manner as in example 1, except that the blending ratio of each component was set as shown in tables 1 to 3. In addition, for the formation of the cured film, examples 2 to 6, 8 to 10 and comparative examples 1 to 4 were heated in the atmosphere, and examples 7 and 11 were heated in the nitrogen atmosphere.

Further, 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 for each cured film 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 phenolic resin contents in tables 1 to 3 are in terms of solid content.

[ Table 1]

[ Table 2]

[ Table 3]

In examples 1 to 11, the cured films all had a resistance value of less than 10.0 Ω, a viscosity change rate of less than 150% before and after continuous printing, and a line width maintenance rate of 70% or more before and after intermittent printing.

In contrast, 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, the viscosity change rate before and after continuous printing was as high as 200% or more, and the line width maintenance rate before and after intermittent printing was as low as less than 70%.

In comparative example 2 in which the conductive composition was prepared without blending the component (b), the line width maintenance ratio before and after the intermittent printing was 70%, but the resistance value of the cured film was as high as 50.0 Ω or more, and the viscosity change ratio before and after the continuous printing was as high as 200% or more.

In comparative example 3 in which a conductive composition was prepared using PEG4000 instead of component (a), although the cured film had a resistance value of less than 10.0 Ω, the viscosity change rate before and after continuous printing was as high as 200% or more, and the line width maintenance rate before and after intermittent printing was as low as less than 50%.

In comparative example 4 in which a conductive composition was prepared using glycerin instead of the component (a), the resistance value of the cured film was as high as 85 Ω.

[ example 12]

The preparation of the conductive composition and the formation of the cured film were carried out in the same manner as in example 1 in accordance with the following compounding ratios. Further, 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 for each cured film in the same manner as in example 1.

Component (a): PEG2001.5g

Component (b): dodecanoic acid 1.5g

Component (c) conductive particles: the surface was covered with 87g of copper particles (1))

Component (d) binder resin: resol type phenol resin 16.7g (solid content: 10g)

Lubricant: magnesium stearate 0.3g

Leveling agent: MEGAFACE F-4770.3 g

Solvent: terpineol 8g

The cured film was evaluated as "o" because the resistance value was 2.5 Ω, and as "excellent" because the viscosity change rate before and after continuous printing was 105%, and as "o" because the line width maintenance rate before and after intermittent printing was 85%.

[ example 13]

Component (a): PEG6001.5g

Component (b): dodecanoic acid 1.5g

Component (d) binder resin: 10g of resol-type phenol resin (solid content: 6g), 4g of bisphenol F-type epoxy resin

Dispersing agent: oleoyl sarcosine 1g

Solvent: terpineol 2g, isobornyl cyclohexanol 6g

The cured film was evaluated as "o" because the resistance value was 1.2 Ω, and as "excellent" because the viscosity change rate before and after continuous printing was 105%, and as "excellent" because the line width maintenance rate before and after intermittent printing was 95%.

Claims

1. An electrically conductive composition comprising: 0.1 to 5 mass% of (a) polyethylene glycol having an average molecular weight of 200 to 2,000, (b) aliphatic monocarboxylic acid having 8 to 18 carbon atoms, (c) conductive particles, and (d) binder resin, 0.1 to 5 mass% of (b) the conductive particles, and (c) 1 to 30 mass% of (d).