JP2023028100A - conductive composition - Google Patents

Abstract

To provide a conductive composition which is good in both continuous printability in screen printing and cold-heat cycle impact resistance of a cured film formed on a substrate, and is usable as a wiring formation material excellent in conductivity.SOLUTION: A conductive composition contains (a) polyethylene glycol having a weight average molecular weight of 200-2,000, (b) at least one compound selected from a predetermined polyether ester having a weight average molecular weight of 200-1,000 and a predetermined adipic acid ester having a weight average molecular weight of 200-3,000, (c) conductive particles and (d) a binder resin, wherein with respect to 100 mass% of the total of components (a) to (d) based on a solid content, a percentage content of the component (a) is 0.1-5 mass%, a percentage content of the component (b) is 0.01-5 mass%, a percentage content of the component (c) is 60-99 mass%, and a percentage content of the component (d) is 0.5-30 mass%.SELECTED DRAWING: None

Description

The present invention relates to conductive compositions.

In recent years, from the viewpoint of Sustainable Development Goals (SDGs), the conventional wet etching method that uses a large amount of chemical solution has been replaced with a printing method using a screen printer or the like in the wiring formation method for electronic parts. ing.

Among them, the development of wiring formation technology using a screen printer, which is a general-purpose printing method, has been actively carried out, and the composition development of conductive paste suitable for screen printing as its material is underway. .

An advantage of wiring formation using screen printing is that continuous printing on a film substrate is possible by a roll-to-roll method. Therefore, for the purpose of improving productivity, the formation of wiring by screen printing is widely studied. However, in order to stably perform continuous printing using a conductive paste, it is necessary to optimize various characteristics of the conductive paste, such as viscosity characteristics and drying properties, according to screen printing conditions.

A characteristic of the roll-to-roll method required for the conductive paste is that the cured film obtained by heating and curing the conductive paste in the roll winding process does not have cracks or disconnections. For example, Patent Literature 1 discloses a silver paste composition that can improve the uniformity of a printed pattern even when manufactured with a high viscosity and can provide a cured film with improved adhesion to a substrate. ing.

Special Table No. 2013-507750

However, although the silver paste composition disclosed in Patent Document 1 is excellent in adhesion to the substrate in the initial stage, deformation of the substrate occurs when the substrate on which the cured film is formed is stored at low temperature or high temperature. The followability of the film and the conductive paste cured film is low, and when the laminate of the film and the conductive paste cured film is subjected to a thermal shock test in which storage is repeated at low and high temperatures, peeling and cracking of the cured film may occur.

The problem to be solved by the present invention is to use it as a wiring forming material that has both good continuous printability in screen printing and good thermal shock resistance of a cured film formed on a substrate and has excellent conductivity. An object of the present invention is to provide a conductive composition capable of

The present inventors have conducted extensive studies to solve the above problems, and as a result, provided a conductive composition capable of solving the above problems by blending specific components in addition to conductive particles and a binder resin. I found that it can be done, and came to complete the present invention.

That is, the present invention provides at least one selected from (a) polyethylene glycol having a weight average molecular weight of 200 to 2000, (b) polyetherester having a weight average molecular weight of 200 to 1000, and adipate ester having a weight average molecular weight of 200 to 3000. Contains one type of compound, (c) conductive particles, and (d) a binder resin, and contains component (a) with respect to a total of 100% by mass of components (a) to (d) on a solid basis The content of component (b) is 0.01 to 5% by mass, the content of component (c) is 60 to 99% by mass, and the content of component (d) is 0.1 to 5% by mass. It relates to a conductive composition that is 5 to 30% by mass.

The conductive composition of the present invention can be used as a wiring forming material with good continuous printability in screen printing, and a cured film formed on a film substrate using the conductive composition can be formed at low or high temperatures. It has a high resistance to substrate deformation at high temperatures, and when subjected to a thermal shock test that repeats storage at low and high temperatures, it is difficult for the resistance value to increase due to peeling or cracking of the cured film (i.e., the cured film good thermal shock resistance), and a wiring pattern exhibiting excellent conductivity can be formed.

Embodiments of the present invention will be described below.

In this specification, the numerical range specified using the symbol "-" includes both ends (upper limit and lower limit) of "-". For example, "2 to 5" represents 2 or more and 5 or less.

Further, when 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", "2 to 4% by mass", "2 to 8% by mass", "4 to 10% by mass" and "8 ~ 10% by mass” is also included.

The conductive composition according to the embodiment of the present invention comprises (a) polyethylene glycol having a weight average molecular weight of 200 to 2000, (b) polyetherester having a weight average molecular weight of 200 to 1000, and adipine having a weight average molecular weight of 200 to 3000. It contains at least one compound selected from acid esters, (c) conductive particles, and (d) a binder resin. Based on the solid content, the content of component (a) is 0.1 to 5% by mass and the content of component (b) is 0.1 to 5% by mass with respect to a total of 100% by mass of components (a) to (d). 01 to 5% by mass, the content of component (c) is 60 to 99% by mass, and the content of component (d) is 0.5 to 30% by mass. Each component will be described below.

[Component (a): polyethylene glycol]
Component (a) is polyethylene glycol and has a weight average molecular weight of 200 to 2000, preferably 400 to 1500, more preferably 500 to 800 from the viewpoint of maintaining wettability. These can be used individually by 1 type, or can also use 2 or more types together.

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

The content of component (a) is 0.1 to 5% by mass, preferably 0.2 to 3% by mass, based on the solid content, with respect to the total 100% by mass of components (a) to (d). is. If the content of component (a) is too small, the film thickness may tend to change as the number of continuous printings by screen printing increases. On the other hand, if the content of component (a) is too high, the electrical conductivity of the conductive composition may decrease.

[Component (b)]
The content of component (b) is 0.01 to 5% by mass, preferably 0.1 to 3% by mass, based on solid content, with respect to 100% by mass of components (a) to (d). is. If the content of component (b) is too low, when the cured film of the conductive composition is subjected to a thermal shock test, peeling or cracking of the cured film may easily cause an increase in resistance value. On the other hand, if the content of component (b) is too high, the electrical conductivity of the conductive composition may decrease.

Component (b) is at least one compound selected from predetermined polyetheresters and predetermined adipate esters. The predetermined polyetherester may be a compound having a weight average molecular weight of 200-1000, preferably a compound having a weight average molecular weight of 400-900.

The above polyetherester can be produced according to a known method, and examples of commercially available products include Adekasizer RS-700 (weight average molecular weight: 550), Adekasizer RS-735 (weight average molecular weight: 850), Adekasizer RS. -966 (weight average molecular weight 470), and ADEKA CIZER RS-1000 (weight average molecular weight 550) (manufactured by ADEKA Corporation).

The predetermined adipate ester may be a compound having a weight average molecular weight of 200 to 3000, preferably a compound having a weight average molecular weight of 1000 to 3000, and more preferably a compound having a weight average molecular weight of 1500 to 2500.

The above adipate can be produced according to a known method, and is also available as a commercial product. Examples of commercially available products include Adekasizer PN-150 (weight average molecular weight: 1000), Adekasizer PN-170 (weight average molecular weight: 1100), Adekasizer P-200 (weight average molecular weight: 2000), Adekasizer PN-350 (weight: Average molecular weight 3000) (manufactured by ADEKA Co., Ltd.), D620 (weight average molecular weight 800), D623 (weight average molecular weight 1800), D643 (weight average molecular weight 1800), D645 (weight average molecular weight 2200), D633 (weight average molecular weight 1800), D620N (weight average molecular weight 800), D623N (weight average molecular weight 1800), D643D (weight average molecular weight 1800), D640A (weight average molecular weight 1200), D671A (weight average molecular weight 650) (J-Plus Co., Ltd. made) and the like.

[Component (c): conductive particles]
Component (c) is a conductive particle, for example inorganic conductive particles such as copper particles can be used. The copper particles may consist only of copper, but may further contain metals other than copper such as silver and platinum, metal oxides, and metal sulfides. 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% by mass or more. Also, 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 whose surfaces are coated for the purpose of improving oxidation resistance. Among them, it is preferable to use surface-coated conductive particles whose surfaces are coated with an amine compound, and it is more preferable to use surface-coated conductive particles whose surfaces are coated with an amine compound represented by the following formula (1).

(In formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any one of 0 to 3, n = 1 or n = 2 when m is one of 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. Conductive particles are preferred.

As a result, the surfaces of the conductive particles are coated with the first coating layer made of the amine compound and the second coating layer made 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 24 carbon atoms is preferable. Examples of the aliphatic monocarboxylic acids include linear saturated aliphatic monocarboxylic acids, linear unsaturated aliphatic monocarboxylic acids, branched saturated aliphatic monocarboxylic acids, and branched unsaturated aliphatic monocarboxylic acids.

Examples of linear saturated aliphatic monocarboxylic acids having 8 to 24 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearin. acid, nonadecylic acid, arachidic acid, and the like. Examples of linear unsaturated aliphatic monocarboxylic acids having 8 to 24 carbon atoms include myristoleic acid, palmitoleic acid, petroselinic acid, and oleic acid. Examples of branched saturated aliphatic monocarboxylic acids having 8 to 24 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.

A method for producing the surface-coated conductive particles is not particularly limited. A method for obtaining surface-coated conductive particles coated with an amine compound includes, for example, washing the conductive particles with an aqueous ammonium chloride solution, etc., and then adding the washed conductive particles to a solution of the amine compound. , a method of heating if necessary, a method of adding conductive particles to a solution containing, for example, ammonium chloride and an amine compound and heating if necessary, and the like.

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 A method of adding the surface-coated conductive particles to a solution of an aliphatic monocarboxylic acid is included. In addition, after adding to the solution of an aliphatic monocarboxylic acid, you may heat as needed.

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. To achieve this, 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 with a laser diffraction/scattering particle size distribution analyzer (Microtrac MT3000II, manufactured by Microtrac Bell Co., Ltd.).

Also, 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 (manufactured by Yuasa Ionics Co., Ltd., Monosorb).

There are no particular restrictions on the shape and aspect ratio of the conductive particles (the ratio of the major axis to the minor axis of the particles), and spherical, polyhedral, flattened, plate-like, flake-like, flaky, rod-like, dendritic, fiber-like, etc. of various shapes can be used. As the conductive particles, one selected from those having different constituents, average particle diameters, shapes, aspect ratios, etc. may be used alone, or two or more thereof may be used in combination.

The content of component (c) is 60 to 99% by mass, based on the solid content, with respect to 100% by mass of components (a) to (d). The lower limit of the content of component (c) is preferably 70% by mass, more preferably 80% by mass.

[Component (d): binder resin]
Component (d) is a binder resin, which acts as a binder in the conductive composition.

As the component (d), known binder resins used in conductive compositions and the like can be used. be able to.

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

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

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

The content of component (d) is 0.5 to 30% by mass, preferably 1 to 20% by mass, based on solid content, with respect to 100% by mass of components (a) to (d). . If the content of component (d) is too low, it may become difficult to impart sufficient fluidity when printing using the conductive composition. If the content of component (d) is too high, the conductive particles of component (c) in the conductive composition may be difficult to contact with each other, making it difficult to obtain a cured film exhibiting excellent conductivity.

In addition, the blending ratio of component (d) can be adjusted according to the type of component (b) contained in the conductive composition for the purpose of improving the adhesion between the cured film obtained from the conductive composition and the substrate. is preferred.

When a predetermined polyether ester is used as the component (b), the blending ratio of the component (d) binder resin is preferably 5% with respect to the total 100% by mass of the components (a) to (d) on a solid basis. It is up to 30% by mass, more preferably 5 to 20% by mass.

When a predetermined adipic acid ester is used as component (b), the blending ratio of component (d) binder resin is preferably 0 with respect to a total of 100% by mass of components (a) to (d) on a solid basis. .5 to 5% by mass, more preferably 1 to 5% by mass.

[Other ingredients]
In addition to the above components (a) to (d), the conductive composition optionally contains a solvent, an antioxidant, a lubricant, a leveling agent, a dispersant, and a curing agent, as long as the effects of the present invention are not impaired. , curing accelerators, viscosity modifiers, foaming agents, antioxidants, and other additives. In addition, the conductive composition may contain impurities that may inevitably be mixed in from raw material components, equipment during the manufacturing process, and the like. In addition, when any of these components is included, the total content can be more than 0 parts by mass and 60 parts by mass or less with respect to 100 parts by mass of the total content of (a) to (d). Part by mass or less is preferable.

(solvent)
The conductive composition may contain a solvent for the purpose of improving coatability and adjusting viscosity.

Examples of solvents include ether-based 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; , 1,4-butanediol and other non-ether alcohols; cyclohexanol acetate, methylmethoxypropionate, ethylethoxypropionate, 1,6-hexanediol acetate and other esters; isophorone, cyclohexanone and other ketones terpenes such as terpineol, dihydroterpineol, dihydroterpinyl acetate and isobornylcyclohexanol; and other hydrocarbons such as octane, decane, dodecane, tetradecane, hexadecane and propylene carbonate.

Among these solvents, it is preferable to use one or more selected from the ether-based alcohols, the esters and the terpenes, and one or more selected from the ether-based alcohols and the terpenes. is more preferred.

The type of solvent is not limited to the above, and one selected from various solvents can be used alone or a mixture of two or more can be used depending on the application. There are no particular restrictions on the mixing ratio when two or more are mixed.

When the conductive composition contains a solvent, the content of the solvent is preferably 1 to 30 parts by mass, more preferably 2 parts by mass, with respect to 100 parts by mass of the total content of components (a) to (d). ~20 parts by mass.

(Antioxidant)
The conductive composition may contain an antioxidant for the purpose of maintaining the performance of each component during storage. Examples of antioxidants include nitrogen-containing heterocyclic compounds such as 2,2-bipyridyl and 1,10-phenanthroline, N,N'-bis(salicylidene)ethylenediamine, and N,N'-bis(salicylidene). Schiff bases such as 1,2-propanediamine, N,N'-bis(salicylidene)-1,3-propanediamine, N,N'-bis(salicylidene)-1,2-phenylenediamine, 1,2 -phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, 2,3,5,6-tetramethyl 1,4-phenylenediamine, N, aromatic diamines such as N-dimethyl-1,4-phenylenediamine, N,N,N'N'-tetramethyl-1,4-phenylenediamine and N,N'-diphenyl-1,4-phenylenediamine; is mentioned.

Among these antioxidants, 2,2-bipyridyl of the above nitrogen-containing heterocyclic compounds, N,N'-bis(salicylidene)ethylenediamine of the above Schiff bases, N,N'-bis(salicylidene)-1 , 2-propanediamine and one or more selected from 1,2-phenylenediamine, 1,3-phenylenediamine and 1,4-phenylenediamine of the aromatic diamines.

The types of antioxidants are not limited to the above, and one selected from various solvents can be used alone or a mixture of two or more can be used depending on the application. There are no particular restrictions on the mixing ratio when two or more are mixed.

When the conductive composition contains an antioxidant, the content of the antioxidant is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the total content of components (a) to (d). Yes, more preferably 0.1 to 5 parts by mass.

(Lubricant)
A lubricant may be appropriately added to the conductive composition for the purpose of adjusting the dispersibility of the component (c) conductive particles in the conductive composition. The types of lubricants and their mixing ratios are not particularly limited, and one type can be used alone, or two or more types can be used in combination, depending on the application.

Types of lubricants include, for example, fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid; Fatty acid metal salts formed by forming salts from metals and the above fatty acids; Fatty acid amides such as stearamide, oleic acid amide, behenic acid amide, palmitic acid amide, and lauric acid amide; Fatty acid esters such as butyl stearate; Paraffin Waxes such as wax and liquid paraffin; alcohols such as ethylene glycol and stearyl alcohol; polysiloxanes such as silicone oil; and fluorine compounds such as fluorine oil.

Among these lubricants, one or more selected from fatty acids and fatty acid metal salts are preferably used, and more preferably at least one selected from lauric acid and magnesium stearate.

When the conductive composition contains a lubricant, the content of the lubricant is preferably 0.01 to 10 parts by mass, more preferably 100 parts by mass of the total content of components (a) to (d). is 0.1 to 5 parts by mass.

(dispersant)
A dispersant can be added to the conductive composition as appropriate for the purpose of adjusting the dispersibility of the conductive particles of component (c) in the conductive composition. The type of dispersant and the mixing ratio thereof are not particularly limited, and one type can be used alone or two or more types can be used in combination depending on the application.

Types of dispersants include, for example, sarcosine compounds such as lauroyl sarcosine, myristoyl sarcosine, palmitoyl sarcosine, stearoyl sarcosine, and oleoyl sarcosine; -107P, Esleem AD-3172M, Esleem AD-374M, Esleem AD-508E, (manufactured by NOF Corporation, "Esleem" is a registered trademark) and other polymeric amine compounds; Marialim AKM-0531, Marialim AFB-1521, Marialim AAB-0851, Marialim AWS-0851, Marialim SC-0505K, Marialim SC-1015F, Marialim SC-0708A (manufactured by NOF Corporation) and other polymeric polycarboxylic acid compounds. be done.

Among these dispersants, one or more selected from sarcosines is preferably used, and more preferably at least one selected from lauroyl sarcosine and oleoyl sarcosine.

When the conductive composition 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 components (a) to (d), More preferably, it is 0.2 to 5 parts by mass.

EXAMPLES The embodiments of the present invention will be described in more detail below with reference to examples and comparative examples.

Components used in Examples and Comparative Examples are shown below. In addition, the physical property of each component is the value measured by the method as described in this specification.

[Component (a): polyethylene glycol]
・PEG200 (polyethylene glycol with a weight average molecular weight of 200)
・PEG600 (polyethylene glycol with a weight average molecular weight of 600)
・PEG2000 (polyethylene glycol with a weight average molecular weight of 2000)

[Component (a'): Polyethylene glycol having a weight average molecular weight exceeding 2000]
・PEG4000 (polyethylene glycol with a weight average molecular weight of 4000)

[Component (a'): polytetramethylene glycol]
・PTMG2000 (polytetramethylene glycol with an average molecular weight of 2000)

[Component (b)]
(b1): ADEKA CIZER RS-1000 (polyether ester, weight average molecular weight 550, manufactured by ADEKA Co., Ltd.)
(b2): ADEKA CIZER P-200 (polyester adipate, weight average molecular weight 2000, manufactured by ADEKA Co., Ltd.)

[Component (b')]
(b3): bis(2-ethylhexyl) phthalate

[Component (c): conductive particles]
· Copper particles (1): spherical copper particles [surface-coated copper particles (1), the production method is shown below. ]
· Copper particles (2): plate-like copper particles [surface-coated copper particles (2), the production method is shown below. ]

[Component (d): binder resin]
Phenolic resin Resol type phenolic resin [PL-5208, manufactured by Gun Ei Chemical Industry Co., Ltd., solid content 60.0% by mass, solvent: diethylene glycol monoethyl ether]
・ Epoxy resin bisphenol F type epoxy resin [jER (registered trademark)-806, manufactured by Mitsubishi Chemical Corporation, solid content 100% by mass]

The following materials were used as other components.

(Antioxidant)
・N,N'-bis(salicylidene)ethylenediamine (lubricant)
・Lauric acid (dispersant)
・Oleoyl sarcosine (solvent)
・Terpineol ・Ethylene glycol monobutyl ether acetate ・Isobornylcyclohexanol

[Synthesis Example 1]
(Copper Particles (1): Production of Surface-Coated Copper Particles (1))
An aqueous ammonium chloride solution was prepared by dissolving 5 g of ammonium chloride in 100 g of water. 50 g of copper particles a ["1200Y" manufactured by Mitsui Mining & Smelting Co., Ltd.; particle diameter (D50) 2 μm, BET specific surface area 0.40 m ² /g, shape: spherical] was added to an aqueous solution of ammonium chloride, and under nitrogen bubbling, Stirred at 30° C. for 60 minutes. Stirring was performed using a mechanical stirrer at a rotation speed of 150 rpm. Thereafter, stirring was performed at the same rotation speed using the same stirring device. After stirring, the copper particles were separated by filtration under reduced pressure using a Kiriyama funnel of 5C filter paper, and then 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 with nitrogen bubbling.

After stirring was stopped and the mixture was allowed to stand for 5 minutes, about 200 g of the supernatant liquid was extracted and removed. Subsequently, 200 g of isopropanol was added as a washing solvent to the precipitate, and the mixture was stirred at 30° C. for 3 minutes. After stirring was stopped and the mixture was allowed to stand for 5 minutes, about 200 g of the supernatant liquid was extracted and removed, and then 250 g of a 2% by mass lauric acid isopropanol solution was added, followed by stirring at 30° C. for 30 minutes.

After the stirring was completed, the copper particles were separated by filtration under reduced pressure 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 (2): Production of Surface-Coated Copper Particles (2))
Same as Synthesis Example 1 except that the copper particles a ^were changed to copper particles b ["1400YP" manufactured by Mitsui Mining & Smelting Co., Ltd.; Similarly, surface-coated copper particles (2) (copper particles (2)) were obtained.

[Example 1]
(Production of conductive composition)

0.5 g of PEG200 as component (a), 0.5 g of (b1) Adekasizer RS-1000 as component (b), 65 g of surface-coated copper particles (copper particles (1)) as component (c), surface coating 28.0 g of copper particles (copper particles (2)), resol-type phenol resin [PL-5208, manufactured by Gunei Chemical Industry Co., Ltd., solid content 60% by mass, solvent: diethylene glycol monoethyl ether] as component (d). 10.0 g (6.0 g as solid content), 0.5 g of N,N'-bis(salicylidene)ethylenediamine (Salen), and 2.0 g of lauric acid were mixed. Next, using a planetary mixer [ARV-310, manufactured by Thinky Co., Ltd.], primary kneading was carried out by stirring at room temperature at a rotation speed of 1500 rpm for 60 seconds.

Next, using a three-roll mill [EXAKT-M80S, manufactured by Nagase Screen Printing Laboratory Co., Ltd.], secondary kneading was performed by passing the mixture five times at room temperature with a roll distance of 5 μm. 4.0 g of terpineol (Ter) was added to the kneaded material obtained by the second kneading, and the mixture was stirred for 90 seconds at room temperature and vacuum conditions at a rotation speed of 1000 rpm for degassing and kneading using a planetary mixer. A sexual composition was produced. Table 1 shows the blending ratio of each component of the conductive composition.

<Evaluation of conductivity>
(Formation of cured film)
The resulting conductive composition was applied onto a polyimide film using a metal mask in a pattern of width×length×thickness=1.0 mm×30 mm×50 μm. A cured film was prepared by heating the polyimide film coated with the conductive composition at 170° C. for 30 minutes in a convection oven.

(Evaluation method of resistance value)
The electrical conductivity of the cured film obtained by the above method was evaluated by the following resistance measurement. A measurement 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 Denki Keiki Co., Ltd.], and judged according to the following evaluation criteria.

The lower the resistance value of the cured film, the easier the current flows, indicating that the conductivity is excellent.
A: The resistance value is less than 1.0Ω.
Good: The resistance value is 1.0Ω or more and less than 10.0Ω.
Δ: The resistance value is 10.0Ω or more and less than 50.0Ω.
x: The resistance value is 50.0Ω or more.

<Evaluation of continuous printability>
(Evaluation method of film thickness change rate before and after continuous printing)
The obtained conductive composition was printed continuously on 50 polyethylene terephthalate (PET) films using a screen printer [MT-320T, manufactured by Micro Tech Co., Ltd.].

A cured film was prepared by heating the resulting printed material at 120° C. for 30 minutes in a convection oven. The film thickness of the cured film of the 1st sheet and the 50th sheet was measured using a stylus type film thickness measuring device [DEKTAK XT, manufactured by Bruker], and the film thickness change rate was obtained by the following formula (I). It was judged according to the evaluation criteria.

In this test, the closer the film thickness change rate is to 100%, the longer the wettability of the conductive composition is maintained during continuous printing, indicating that the wiring pattern can be stably printed.

A: The film thickness change rate is 90% or more and 100% or less.
○: The film thickness change rate is 70% or more and less than 90%.
Δ: The film thickness change rate is 50% or more and less than 70%.
x: The film thickness change rate is less than 50%.

<Evaluation of thermal shock resistance>
(Method for evaluating thermal shock resistance)
A cured film obtained in the same manner as the cured film used in the evaluation of conductivity was used as a measurement sample for the thermal shock test. A measurement sample is placed in a small thermal shock apparatus [TSE-11, manufactured by Espec Co., Ltd.], held at -40 ° C. for 1 minute, then heated to 100 ° C. and held for 2 minutes. The test was performed by repeating 1000 cycles.

The resistance value is measured by pressing the measurement probe of a digital multimeter [PC7000, manufactured by Sanwa Denki Keiki Co., Ltd.] against both ends of the cured film after the test, and the resistance value change rate is calculated by the following formula (II). It was determined according to the following evaluation criteria.

In this test, the closer the resistance value change rate is to 100%, the better the thermal shock resistance of the cured film.

Resistance value change rate (%) = (resistance value after test) / (resistance value before test) x 100 (II)

A: The rate of change in resistance value is less than 110%.
○: The rate of change in resistance value is 110% or more and less than 150%.
Δ: The rate of change in resistance value is 150% or more and less than 200%.
x: Resistance value change rate is 200% or more.

Table 1 shows the above evaluation results.

[Examples 2 to 8, Comparative Examples 1 to 5]
A conductive composition was produced and a cured film was formed in the same manner as in Example 1, except that the blending ratio of each component was as shown in Table 1. Regarding the formation of the cured film, Examples 2 to 4 and Comparative Examples 1 and 5 were heated in an air atmosphere, and Examples 5 to 8 and Comparative Examples 2 to 4 were heated in a nitrogen atmosphere.

Further, each cured film was evaluated in the same manner as in Example 1 for electrical conductivity, continuous printability, and thermal shock resistance. Tables 1 and 2 show the results. In addition, the content of the phenolic resin in Tables 1 and 2 is the amount in terms of solid content.

Tables 1 and 2 show the following.
In Examples 1 to 8, the resistance values of the cured films are all less than 10.0 Ω, the resistance value change rate before and after the thermal shock test is less than 150%, and the film thickness change rate before and after continuous printing is 70% or more. is. On the other hand, in Comparative Example 1 in which the conductive composition was prepared without blending the component (a), the resistance value change rate before and after the thermal shock test was less than 150%, but the resistance value of the cured film was It was as high as 10.0Ω or more, and the film thickness change rate before and after continuous printing was as low as less than 50%. In addition, in Comparative Example 2, in which the conductive composition was prepared without blending the component (b), the resistance value of the cured film was less than 1.0Ω, and the film thickness change rate before and after continuous printing was less than 90%. However, the rate of change in resistance value before and after the thermal shock test was as high as 200% or more. In Comparative Example 3, in which a conductive composition was prepared using PEG4000 instead of component (a), the rate of change in resistance value before and after the thermal shock test was less than 150%, but the resistance value of the cured film was 10.0Ω. It was as high as above, and the film thickness change rate before and after continuous printing was as low as less than 70%. In addition, in Comparative Example 4 in which a conductive composition was prepared using PTMG2000 instead of component (a), the rate of change in resistance value before and after the thermal shock test was less than 150%, but the resistance value of the cured film was 50%. It was as high as 0Ω or more, and the film thickness change rate before and after continuous printing was as low as less than 50%. In Comparative Example 5, in which the conductive composition was prepared using (b3) bis(2-ethylhexyl) phthalate instead of component (b), the resistance value of the cured film was less than 10.0 Ω, and before and after continuous printing Although the film thickness change rate was less than 90%, the resistance value change rate before and after the thermal shock test was as high as 150% or more.

As described above, the conductive composition containing the predetermined components (a) to (d) in a predetermined ratio has good continuous printability, and also has good thermal shock resistance when formed into a cured film. It can be seen that it is suitable as a wiring forming material with excellent conductivity.

Claims (1)

(a) polyethylene glycol having a weight average molecular weight of 200 to 2000;
(b) at least one compound selected from polyetheresters having a weight average molecular weight of 200 to 1000 and adipate esters having a weight average molecular weight of 200 to 3000;
(c) conductive particles, and (d) a binder resin,
Based on the solid content, the content of component (a) is 0.1 to 5% by mass and the content of component (b) is 0.01 to 0.01%, based on the total 100% by mass of components (a) to (d). 5% by mass, a content of component (c) of 60 to 99% by mass, and a content of component (d) of 0.5 to 30% by mass.