JP2024020841A - conductive composition - Google Patents

Abstract

To provide a conductive composition that has low surface dryness when applied to a substrate, has low temperature dependence of viscosity in a low temperature region, and can form a cured product that is highly conductive.SOLUTION: A conductive composition (A) contains a diglycidyl ether represented by the general formula (1) in the figure, (B) a phenolic resin, and (C) conductive particles. The content of the component (A) is 0.2 to 38 mass%, the content of the component (B) is 0.05 to 32 mass%, and the content of the component (C) is 60 to 99 mass%, based on 100 mass% of the total of the components (A) to (C) on a solid content basis. In the general formula (1), m represents the average number of moles of oxytrimethylene groups added, and is a real number from 2 to 90.SELECTED DRAWING: None

Description

The present invention relates to a conductive composition, and particularly to a conductive composition containing a diglycidyl ether having a polytrimethylene glycol structure and a phenol resin as a binder.

Thermosetting resin compositions that are a combination of epoxy resins and phenolic resins have been used as binders for various purposes since ancient times. A thermosetting resin composition that is a combination of an epoxy resin and a phenol resin has excellent electrical and mechanical properties, as well as excellent adhesion to a substrate. Among them, it is often used as a binder for copper-based conductive compositions, and has a characteristic that it can exhibit high conductivity due to its high antioxidant properties compared to other resin systems.

When using a thermosetting resin composition that combines the above-mentioned epoxy resin and phenol resin as a binder for copper particles, a paste with excellent conductivity (conductive composition) can be obtained. When applied, a unique phenomenon occurs in which the surface dries extremely rapidly in the atmosphere. When the copper paste is heated and cured, this surface drying forms a dry film on the surface, which significantly inhibits the volatilization of the solvent remaining inside the copper paste, and causes damage to the inside of the cured film, the copper paste, or the cured film and the base material. There is a problem in that voids are formed at the interface, leading to a decrease in adhesion and conductivity.

Patent Document 1 discloses that by using a combination of a specific monocarboxylic acid and a specific bipyridine derivative at a content within a predetermined range, the above-mentioned surface drying of the paste can be suppressed and the pot life in the atmosphere can be increased. A method of stretching is disclosed.

In addition, in recent years, plastic base materials with low heat resistance such as polyethylene terephthalate (PET) have been increasingly used as housings due to the effects of devices becoming lighter and more wearable. There is an increasing need for curing at a temperature lower than the glass transition temperature of the plastic base material, and improvements in low-temperature curing of conductive compositions are progressing. On the other hand, low-temperature curing type conductive compositions have a short pot life and harden gradually at room temperature, so they must be stored in a low-temperature storage such as a freezer until just before use. However, the conductive composition removed from low-temperature storage has a high viscosity when it is cold, and when it is applied by screen printing, it causes clogging and smearing, leading to a decrease in yield when manufacturing devices. .

Patent Document 2 discloses that temperature dependence at low temperatures is improved by adding a reaction product of polyethylene glycol, hexamethylene diisocyanate, and diallylamine to a pigment paste as a viscosity modifier.

However, Patent Documents 1 and 2 disclose, for example, a conductive paste that has low surface drying properties when applied to a base material, has low temperature dependence of viscosity in a low temperature range, and has a highly conductive cured product. (Conductive composition) is not described, and development of a conductive composition having such characteristics has been desired.

JP2021-57185A Japanese Unexamined Patent Publication No. 11-199854

From the above-mentioned background, the object of the present invention is to provide a conductive material that has low surface drying properties when applied to a substrate, has low temperature dependence of viscosity in a low temperature range, and has a highly conductive cured product. An object of the present invention is to provide a composition.

In view of the above-mentioned problems, the present inventor conducted various studies and found that, in a conductive composition containing conductive particles, by using a diglycidyl ether having a specific polytrimethylene glycol structure and a phenol resin in combination as a binder, It has been found that the above problems can be solved.

That is, the present invention relates to the following conductive composition.

(A) diglycidyl ether represented by the following general formula (1),
(B) Phenol resin,
(C) containing conductive particles;
The content of component (A) is 0.2 to 38 mass %, and the content of component (B) is 0.05 to 32 mass %, based on the solid content of 100 mass % in total of components (A) to (C). A conductive composition in which the content of component (C) is 60 to 99% by mass.

(In general formula (1), m represents the average number of added moles of oxytrimethylene groups and is a real number from 2 to 90.)

According to the present invention, there is provided a conductive composition that has low surface drying properties when applied to a substrate, has low temperature dependence of viscosity in a low temperature range, and has a highly conductive cured product. be able to.

Embodiments of the present invention will be described below, but the present invention is not limited thereto.

The conductive composition according to the embodiment of the present invention includes (A) diglycidyl ether represented by the following general formula (1) (hereinafter sometimes referred to as polytrimethylene glycol diglycidyl ether), (B) phenol. Contains resin and (C) conductive particles. The content of component (A) is 0.2 to 38% by mass and the content of component (B) is 0.05% by mass based on the total of 100% by mass of components (A) to (C) on a solid content basis. ~32% by weight, and the content of component (C) is 60~99% by weight.

(In general formula (1), m represents the average number of added moles of oxytrimethylene groups and is a real number from 2 to 90.)

Each component contained in the conductive composition will be explained below.

[Polytrimethylene glycol diglycidyl ether (component (A))]
As the polytrimethylene glycol diglycidyl ether, diglycidyl ether represented by the above-mentioned general formula (1) is used.

In the general formula (1), m represents the average number of added moles of oxytrimethylene groups, and is a real number from 2 to 90. From the viewpoint of the conductivity of the cured product of the conductive composition, m is preferably a real number of 5 to 50, more preferably a real number of 5 to 40, even more preferably a real number of 5 to 25, and a real number of 5 to 10. Most preferred.

The epoxy equivalent of polytrimethylene glycol diglycidyl ether is 200 to 1500 g/eq. from the viewpoint of conductivity of the cured product of the conductive composition during low-temperature curing. is preferably 200 to 1200 g/eq. is more preferable

Here, the epoxy equivalent refers to the mass of a compound containing 1 equivalent of epoxy group, and can be measured and calculated by a method based on JIS K7236.

From the viewpoint of handling properties, the viscosity of polytrimethylene glycol diglycidyl ether is preferably 1 to 100,000 mPa·s, more preferably 25 to 10,000 mPa·s, and even more preferably 50 to 1,000 mPa·s at 25°C. Viscosity can be measured according to JIS Z 8803. Further, the weight average molecular weight of polytrimethylene glycol diglycidyl ether is preferably 50 to 6,000 from the viewpoint of influence on viscosity. The weight average molecular weight can be measured in terms of polyethylene glycol by GPC using tetrahydrofuran (THF) as a developing solvent.

As the polytrimethylene glycol diglycidyl ether, one having a specific value of m represented by the general formula (1) may be used alone, or two or more types having different values of m may be used in combination.

The content of polytrimethylene glycol diglycidyl ether is determined based on the total 100% by mass of components (A) to (C) from the viewpoint of ensuring conductivity, suppressing surface dryness, and suppressing temperature dependence of viscosity. , based on solid content, from 0.2 to 38% by mass, preferably from 0.2 to 20% by mass, more preferably from 0.5 to 10% by mass, even more preferably from 1 to 5% by mass. be.

[Production method of polytrimethylene glycol diglycidyl ether]
The aforementioned polytrimethylene glycol diglycidyl ether can be obtained, for example, by ring-addition reaction of epichlorohydrin to a predetermined polytrimethylene glycol.

Specifically, polytrimethylene glycol and epichlorohydrin having a predetermined average number of added moles are combined with an acidic catalyst such as sulfuric acid, boron trifluoride ethyl ether, tin tetrachloride, or quaternary ammonium salts, quaternary After forming a chlorohydrin ether intermediate by reacting in the presence of a phase transfer catalyst such as bosphonium salts or crown ethers, this chlorohydrin ether is then subjected to dehydrohalogenation using sodium hydroxide, etc. The polytrimethylene glycol diglycidyl ether represented by the general formula (1) can be obtained by a method called a two-step method in which ring closure is performed by reacting with a compound. Polytrimethylene glycol having a predetermined average number of added moles can be prepared according to a conventional method, but commercially available products can also be used.

Polytrimethylene glycol becomes a liquid when heated until its weight average molecular weight is around 2000, so it can be processed without a solvent, but the viscosity can be lowered by using a solvent, so a stirrer is required. It is also possible to do this in accordance with the performance of However, if a solvent is present, there is a possibility that some amount of the solvent may remain in the final product, so it is preferable to carry out the process without a solvent.

The solvent is not particularly limited as long as it does not inhibit the reaction. Usable solvents include, for example, aromatic hydrocarbon solvents such as toluene and xylene; hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; halogenated hydrocarbon solvents such as dichloromethane and chloroform; and diethyl ether and tetrahydrofuran. Examples include ether solvents; ketone solvents such as acetone, ethylmethylketone, and 4-methyl-2-pentanone; sulfoxide solvents such as dimethyl sulfoxide; and water.

The reaction temperature and reaction time may be determined as appropriate. For example, if the reaction temperature is raised, the reaction can be promoted, but if it is too high, gelation due to addition reaction or the like may occur. Therefore, the specific reaction temperature can be about 20°C or higher and 120°C or lower. When a solvent is used, a reflux operation may be performed or a Dean-Stark apparatus may be used.

Regarding the reaction time, it is sufficient to carry out the reaction until the reaction is completed, and specifically, it can be set to 1 hour or more and about 40 hours. The progress of the reaction can be monitored by thin layer chromatography, gas chromatography, or the like.

After the reaction is completed, catalyst residues, salts, impurities, etc. are contained, so normal post-treatment may be performed. Specifically, water that is immiscible with polytrimethylene glycol diglycidyl ether or a solvent such as toluene may be added, impurities may be extracted and removed from the solvent side for purification, and then the solvent may be distilled off. In addition, removal by general purification methods such as column chromatography is also possible.

The obtained polytrimethylene glycol diglycidyl ether can be specified, for example, by its epoxy equivalent and weight average molecular weight.

[Phenol resin (component (B))]
The phenol resin may be any resin obtained by reacting a compound containing a phenolic hydroxyl group with an aldehyde such as formaldehyde under an acid or alkali catalyst. The molecular weight is not particularly limited, but it is preferably 2,000 to 20,000 in terms of weight average molecular weight. When the weight average molecular weight is within this range, sufficient film strength after curing can be obtained, the curing rate is also within an appropriate range, and handling properties are also good. Further, from the viewpoint of the balance between curing speed and viscosity, the weight average molecular weight of the phenol resin is preferably 3,000 to 15,000, more preferably 3,500 to 12,000. Note that the weight average molecular weight can be determined in terms of polyethylene using gel permeation chromatography (GPC).

There are various phenolic hydroxyl compounds such as phenol, pyrazole, and hydroquinone, but those having a phenol structure are preferred from the viewpoint of crosslinking properties. The aldehyde is preferably formaldehyde. As the phenol resin, a novolac type phenol resin is preferable.

From the viewpoint of conductivity, the phenol resin is 0.05 to 32 mass%, preferably 0.05 to 20 mass%, based on solid content, based on the total 100 mass% of components (A) to (C). %, more preferably 0.5 to 10% by weight, still more preferably 1 to 5% by weight.
[Conductive particles (component (C))]

The conductive particles may be any conductive particles, and for example, conductive particles such as gold, silver, copper, carbon, nickel, etc. can be used. Among these, the copper particles may be made of only copper, but may also contain metals other than copper, such as silver or 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. Further, the copper particles may have a shape in which a surface layer or protrusions are formed.

Although commercially available conductive particles may be used as they are, 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 (2).

(In formula (2), 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, and when n=1 or n=2 , m is any one from 1 to 3.)

Surface-coated conductive particles whose surfaces are coated with an amine compound such as the amine compound represented by the above formula (2) 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 a first coating layer made of an amine compound and a second coating layer made of an aliphatic monocarboxylic acid. Preferably, the first coating layer is formed on the surface of the conductive particle, and the second coating layer is formed on the first coating layer.

The aliphatic monocarboxylic acid forming the second coating layer is preferably an aliphatic monocarboxylic acid having 8 to 24 carbon atoms. 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, etc. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 24 carbon atoms include myristoleic acid, palmitoleic acid, petroselic acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 24 carbon atoms include 2-ethylhexanoic acid.

As the aliphatic monocarboxylic acid, one type selected from the above compounds can be used alone, or two or more types can be used in combination.

The method for producing 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, the conductive particles are washed with, for example, an aqueous ammonium chloride solution, and then the washed conductive particles are added to a solution of the amine compound. , a method of heating as necessary, and a method of adding conductive particles to a solution containing, for example, ammonium chloride and an amine compound and heating as necessary.

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, A method of adding surface-coated conductive particles to a solution of an aliphatic monocarboxylic acid may be mentioned. In addition, after adding to the aliphatic monocarboxylic acid solution, heating may be performed as necessary.

The average particle diameter (D50) of the conductive particles is not particularly limited, but the conductive composition containing the conductive particles as component (C) can be printed well in various printing methods such as inkjet printing and screen printing. In order to achieve this, it is preferable to control the average particle diameter (D50) of the conductive particles. Specifically, the average particle diameter (D50) of the conductive particles is preferably 5 nm to 20 μm, more preferably 10 nm to 10 μm. The average particle diameter (D50) of the conductive particles can be measured using a laser diffraction/scattering particle size distribution analyzer (Microtrac 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.).

There are no particular restrictions on the shape or aspect ratio (ratio of the major axis to the minor axis of the particles) of the conductive particles, and they may be spherical, polyhedral, flat, plate-shaped, flaky, flaky, rod-shaped, dendritic, fibrous, etc. Various shapes can be used. As the conductive particles, one type selected from those having different constituent components, average particle size, shape, aspect ratio, etc. can be used alone, or two or more types can be used in combination.

From the viewpoint of conductivity, the content of component (C) is 60 to 99% by mass, preferably 80 to 96% by mass, based on the solid content, based on the total of 100% by mass of components (A) to (C). % by mass, more preferably 85 to 95% by mass.

In addition to the above-mentioned components (A) to (C), the conductive composition can contain a curing accelerator (component (D)), a solvent (component (E)), and other components described below.

[Curing accelerator (component (D))]
The conductive composition may contain a curing accelerator. As the curing accelerator, a known curing accelerator for curing a known epoxy resin with a phenolic curing agent can be used, such as tertiary amine compounds, quaternary ammonium salts, imidazoles, urea compounds, phosphine compounds, Examples include phosphonium salts. Specifically, for example, triethylamine, triethylenediamine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) or its like. salts (more specifically phenol salts, octylate (2-ethylhexanoate), p-toluenesulfonate, formate, tetraphenylborate salts, etc.), 1,5-diazabicyclo[4.3.0 ] Nonene-5 (DBN) or its salts (e.g., phenol salt, octylate (2-ethylhexanoate), p-toluenesulfonate, formate, tetraphenylborate salt, etc.), triphenylphosphine, etc. Examples include phosphines, phosphonium compounds such as tetraphenylphosphonium tetra(p-tolyl)borate, organic metal salts such as zinc octylate and tin octylate, and metal chelates. One type of curing accelerator can be used alone, or two or more types can be used in combination.

When using a curing accelerator, its content is preferably 0.05 to 10 parts by mass, and preferably 0.1 to 5 parts by mass, based on a total of 100 parts by mass (solid content basis) of component (A) and component (B). Parts by mass are more preferred. When the content of the curing accelerator is within the above range, the curing accelerating effect is sufficient and the hue of the cured product does not change over time.

[Solvent (component (E))]
The conductive composition may contain a solvent as a volatile component. As the solvent, for example, organic solvents commonly used in this technical field can be used. Examples include glycol ethers, non-ether alcohols, esters, ketones, terpenes, and other hydrocarbons. Examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monoethyl ether acetate. Examples of non-ether alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, and cyclohexanol. Examples of the esters include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of terpenes include turpentine oil, terpineol, borneol, and α-pinene. Further, from the viewpoint of handling properties, the solvent may be used as a diluent in the resin. The solvents may be used alone or in combination of two or more.

The content of the solvent is preferably 0 to 250 parts by weight, more preferably 20 to 100 parts by weight, based on a total of 100 parts by weight (based on solid content) of components (A) and (B). In addition, if a solvent is included in the above-mentioned components (A) to (D) and other optional components described later, this should be taken into consideration.

[Other ingredients]
The conductive composition may contain various known additives such as dispersants, antioxidants, surfactants, fillers, flame retardants, coupling agents, antifoaming agents, and lubricants as necessary to ensure conductivity. They may be blended within the possible range.

The conductive composition is a resin composition that is cured by heating to form a cured product having conductivity. The conductive composition is liquid and can be easily patterned using various coating machines such as a die coater, an inkjet printer, a screen printer, a gravure offset printer, and a pad printer. In this case, the viscosity of the conductive composition at 25° C. is preferably, for example, 500 mPa·s or more and 300 Pa·s or less. Preferably, it is liquid and homogeneous at 25°C. Conductive compositions have low temperature dependence of viscosity in low-temperature ranges, and have more fluidity than conventional conductive compositions, especially at medium-low temperatures where they return to room temperature after being taken out of a cold storage such as a refrigerator or freezer. However, it is preferable to have fluidity similar to that at room temperature.

Furthermore, when the conductive composition is applied to a substrate, for example, the surface drying property in the atmosphere is lower than that of conventional compositions, but it is preferable that the conductive composition is not affected by drying. If the surface of the conductive composition dries quickly, a dry coating film is immediately formed on the surface during heat curing, inhibiting the volatilization of the solvent remaining inside the conductive composition to the outside, and creating voids inside. Many will remain. The generation of these voids leads to defects in the cured film and a decrease in conductivity.

Since the conductive composition contains conductive fine particles and a binder at a predetermined content rate, the cured product thereof has higher conductivity than before, but it is desirable that the cured product has higher conductivity. From the viewpoint of driving the device, the volume resistivity is preferably 100 μΩ·cm or less, for example. Further, it is preferable that the cured product has excellent migration resistance.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Measurement of epoxy equivalent of diglycidyl ether]
After diluting and dissolving 3 g of diglycidyl ether obtained in Examples 1 to 3 and Comparative Examples 1 to 5, which will be described later, in dimethylformamide (DMF), a 0.2N hydrochloric acid DMF solution was added and left for 1 hour. Then, after adding a bromophenol blue indicator, titration was performed with a 0.2N potassium hydroxide ethanol solution, and the epoxy equivalent was calculated from the amount of oxirane oxygen.

[Measurement of viscosity of diglycidyl ether]
The viscosity of the diglycidyl ethers obtained in Examples 1 to 3 and Comparative Examples 1 to 5 described below after 5 minutes at 25°C using a cone-plate type E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) The value was read.

[Measurement of average number of added moles of diglycidyl ether]
The diglycidyl ethers obtained in Examples 1 to 3 and Comparative Examples 1 to 4, which will be described later, were measured by GPC (gel permeation chromatography, manufactured by Shimadzu Corporation) using tetrahydrofuran (THF) as a developing solvent, and polyethylene glycol The weight average molecular weight was determined in terms of conversion, and the average number of added moles was calculated.

[Example 1]
<Synthesis of polytrimethylene glycol diglycidyl ether ((A-1) component)>
In a 5L five-necked flask equipped with a dropping funnel, a stirring blade, and a thermometer, 1500 g of polytrimethylene glycol [Velvetol H-500 [molecular weight 500], manufactured by ALLESSA Co., Ltd., and 1500 g of epichlorohydrin [manufactured by Daiso Co., Ltd., Epichloro hydrin] and 13.5 g of a 65% aqueous solution of tetramethylammonium chloride were charged, and the temperature was raised to 60°C. Thereafter, 560 g of a 48% aqueous sodium hydroxide solution was added dropwise over 3 hours. Thereafter, heating and stirring were performed at 55° C. for 5 hours. Thereafter, after cooling to room temperature, 750 g of water was added dropwise to the flask, and after stirring for 10 minutes, the flask was transferred to a 5 L separatory funnel and left to stand for 30 minutes. After confirming the separation of the layers, the lower aqueous layer was discharged. Next, 300 g of water was added and mixed, and then left to stand for 30 minutes. After confirming the separation of the layers, the upper aqueous layer was separated. The same operation was repeated three additional times. Thereafter, after returning to the flask, water was distilled off under reduced pressure (80° C. x 50 torr (6.7 kPa) x 6 hours) to obtain polytrimethylene glycol diglycidyl ether (A-1) in a yield of 72%. Epoxy equivalent is 360g/eq. The weight average molecular weight was 650, and the viscosity at 25°C was 137 mPa·s. Further, the average number of added moles m in the general formula (1) was 9.

<Manufacture of surface-coated copper particles (B-1)>
An ammonium chloride aqueous solution was prepared by dissolving 50 g of ammonium chloride in 1000 g of water. 300 g of copper particles a [Mitsui Kinzoku Mining Co., Ltd. "1200Y"; particle size (D50) 2 μm, BET specific surface area 0.40 m ² /g, shape: spherical] were added to an ammonium chloride aqueous solution, and under nitrogen bubbling, The mixture was stirred at 30°C for 60 minutes. Stirring was performed using a mechanical stirrer at a rotation speed of 150 rpm. Hereinafter, stirring was performed using the same stirring device at the same rotation speed. After the stirring was completed, the copper particles were filtered out by vacuum filtration using a Kiriyama funnel made of 5C filter paper, and then the copper particles were washed twice with 1500 g of water on the Kiriyama funnel. The washed copper particles were added to 2,500 g of a 40% by mass diethylenetriamine aqueous solution, and heated and stirred at 60° C. for 1 hour under nitrogen bubbling. After the stirring was stopped and the mixture was allowed to stand for 5 minutes, about 2000 g of supernatant liquid was drawn out and removed. Subsequently, 2000 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 the mixture to stand for 5 minutes, about 2000 g of the supernatant liquid was extracted and removed, and then 2500 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, copper particles were removed by vacuum filtration using a Kiriyama funnel made 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 (B-1).

<Preparation of conductive composition>
3.3 parts by mass (solid content basis) of the obtained polytrimethylene glycol diglycidyl ether (A-1), phenol resin (manufactured by Gunei Chemical Co., Ltd., PSF-2803, novolak type phenol resin, weight average molecular weight: 12,000) (based on solid content), 87.8 parts by mass of surface-treated copper powder (B-1), and a quaternary ammonium salt (organic acid base catalyst) as a curing accelerator (San-Apro Co., Ltd. 0.2 parts by mass (based on solid content) of U-CAT SA102, DBU (2-ethylhexanoate), NAA (registered trademark)-122 (manufactured by NOF Corporation, lauric acid) as a dispersant, oxidation After blending 3.3 parts by mass of N,N'-bis(2-hydroxybenzylidene)ethylenediamine (Salen) as an inhibitor and 3.3 parts by mass of diethylene glycol monoethyl ether acetate (ECA) as a solvent, a container stirring type planetary mixer was used. After stirring at 2000 rpm for 1 minute, the mixture was kneaded in a three-roll mill to obtain a conductive composition.

[Example 2]
<Synthesis of polytrimethylene glycol diglycidyl ether ((A-2) component)>
(A-1) except that 1500 g of polytrimethylene glycol [Velvetol H-500 [molecular weight 500], manufactured by ALLESSA Co., Ltd. was changed to 750 g of polytrimethylene glycol [Velvetol H-1000 [molecular weight 1000], manufactured by ALLESSA Co., Ltd. ), polytrimethylene glycol diglycidyl ether (A-2) was obtained in a yield of 69%. Epoxy equivalent is 620g/eq. The weight average molecular weight was 1100, and the viscosity at 25°C was 260 mPa·s. Further, the average number of added moles m in the general formula (1) was 17.

<Preparation of conductive composition>
A conductive composition was obtained in the same manner as in Example 1, except that polytrimethylene glycol diglycidyl ether (A-2) was used instead of polytrimethylene glycol diglycidyl ether (A-1).

[Example 3]
<Synthesis of polytrimethylene glycol diglycidyl ether (component (A-3))>
(A-1) except that 1500 g of polytrimethylene glycol [Velvetol H-500 [molecular weight 500], manufactured by ALLESSA Co., Ltd. was changed to 375 g of polytrimethylene glycol [Velvetol H-2000 [molecular weight 2000], manufactured by ALLESSA Co., Ltd. ), polytrimethylene glycol diglycidyl ether (A-3) was obtained in a yield of 71%. Epoxy equivalent is 1160g/eq. The weight average molecular weight was 2100, and the viscosity at 25°C was 415 mPa·s. Further, the average number of added moles m in the general formula (1) was 34.

<Preparation of conductive composition>
A conductive composition was obtained in the same manner as in Example 1, except that polytrimethylene glycol diglycidyl ether (A-3) was used instead of polytrimethylene glycol diglycidyl ether (A-1).

[Comparative example 1]
<Preparation of conductive composition>
Examples except that polyethylene glycol diglycidyl ether (A'-1) [Epiol (registered trademark) E-1000, manufactured by NOF Corporation] was used instead of polytrimethylene glycol diglycidyl ether (A-1). A conductive composition was obtained in the same manner as in Example 1. In addition, the epoxy equivalent of (A'-1) is 580 g/eq. The weight average molecular weight was 1300, the viscosity at 25° C. was 58 mPa·s, and the average number of added moles of oxyethylene units was 23.

[Comparative example 2]
<Synthesis of polypropylene glycol diglycidyl ether ((A'-2) component)>
Except that 1500 g of polytrimethylene glycol [manufactured by ALLESSA, Velvetol H-500 [molecular weight 500]] was replaced with 750 g of polypropylene glycol [manufactured by NOF Corporation, Uniol (registered trademark) D-1000 [molecular weight 1000]]. Polypropylene glycol diglycidyl ether (A'-2) was synthesized in the same manner as for component A-1) in a yield of 65%. The epoxy equivalent of (A'-2) is 600 g/eq. The weight average molecular weight was 1100, and the viscosity at 25°C was 190 mPa·s. Further, the average number of moles added of the propylene glycol-based structural unit in (A'-2) was 17.

<Preparation of conductive composition>
A conductive composition was obtained in the same manner as in Example 1, except that polypropylene glycol diglycidyl ether (A'-2) was used instead of polytrimethylene glycol diglycidyl ether (A-1).

[Comparative example 3]
<Synthesis of polytetramethylene glycol diglycidyl ether ((A'-3) component)>
For component (A-1), except that 1500 g of polytrimethylene glycol [manufactured by ALLESSA, Velvetol H-500 [molecular weight 500]] was changed to 750 g of polytetramethylene glycol [manufactured by Mitsubishi Chemical, PTMG1000 [molecular weight 1000]] Polytetramethylene glycol diglycidyl ether (A'-3) was obtained in a yield of 66%. The epoxy equivalent of (A'-3) is 610 g/eq. The weight average molecular weight was 1100, and the viscosity at 25°C was 390 mPa·s. Further, the average number of moles of oxytetramethylene units added in (A'-3) was 14.

<Preparation of conductive composition>
A conductive composition was prepared in the same manner as in Example 1 except that polytetramethylene glycol diglycidyl ether (A'-3) was used instead of polytrimethylene glycol diglycidyl ether (A-1). Obtained.

[Comparative example 4]
<Preparation of conductive composition>
Instead of polytrimethylene glycol diglycidyl ether (A-1), diglycidyl ether (A'-4) [manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 828, bisphenol A type epoxy resin, epoxy equivalent: 190 g/ An electrically conductive composition was obtained in the same manner as in Example 1, except that the following was used.

[Comparative example 5]
<Preparation of conductive composition>
Polytrimethylene glycol diglycidyl ether (A-1) and a self-condensing phenol resin (manufactured by Gun-ei Chemical Co., Ltd., PL-5203, resol A conductive composition was prepared in the same manner as in Example 1, except that a phenolic resin (type phenolic resin) was used.

[evaluation]
[Viscosity ratio at room temperature and low temperature]
The viscosity of the conductive compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 5 was measured using an E-type viscometer at 25° C. (normal temperature) and 15° C. (low temperature) at a rotation speed of 5 rpm. The obtained viscosity at 15° C. (η (15° C.)) was divided by the viscosity at 25° C. (η (25° C.)), which was defined as the viscosity ratio, and was evaluated based on the following criteria.
◎: η(15℃)/η(25℃)<1.1
○: 1.1≦η(15℃)/η(25℃)<1.8
×: 1.8≦η(15℃)/η(25℃)

[Surface drying property]
The conductive compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were applied onto a slide glass in a width of 1 cm, length of 3 cm, and thickness of 50 μm, and after 6 hours, they were cured at 150° C. for 15 minutes. Thereafter, the glass surface was observed from the back side, and the presence or absence of voids was visually confirmed. The evaluation criteria are as follows.
○: No void ×: With void

[Conductivity]
The composition was applied onto a slide glass in a width of 1 cm, length of 3 cm, and thickness of 50 μm, and after curing at 150° C. for 15 minutes, the volume resistivity was measured using a four-probe method. The evaluation criteria are as follows.
○:＜100μΩ・cm
×: ≧100μΩ・cm

The formulations and evaluation results of Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1. In Table 1, the numerical values in parentheses in the evaluation column indicate measured values.

From the above results, the conductive composition containing polytrimethylene glycol diglycidyl ether (A-1 to A-3), phenol resin, and conductive particles (B-1) at a predetermined content can be applied to a glass substrate. It has low surface drying properties when cured, has low temperature dependence of viscosity in low temperature ranges, and has a highly conductive cured product, making it suitable for wiring materials and bonding materials.

Claims (1)

(A) diglycidyl ether represented by the following general formula (1),
(B) Phenol resin,
(C) containing conductive particles;
The content of component (A) is 0.2 to 38 mass %, and the content of component (B) is 0.05 to 32 mass %, based on the solid content of 100 mass % in total of components (A) to (C). A conductive composition in which the content of component (C) is 60 to 99% by mass.

(In general formula (1), m represents the average number of added moles of oxytrimethylene groups and is a real number from 2 to 90.)