JP2017214548A - Conductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive resin composition that has even lower resistance and better conductivity than before, and also excels in dispersibility as a composition.SOLUTION: A conductive resin composition contains (A) conductive powder, (B) thermoplastic resin, (C) bisphenol type epoxy resin, (D) latent curing agent, (E) boron compound, (F) silica, and (G) solvent.SELECTED DRAWING: None

Description

  The present invention relates to a conductive resin composition (hereinafter also simply referred to as “composition”).

  Thermosetting conductive resin compositions have been widely used in the formation of electrodes, electrical wiring, and the like by coating or printing on a film substrate, a glass substrate, or the like and then curing by heating.

  Particularly recently, with the improvement in performance of electronic devices, electrodes, electrical wiring, and the like formed using a conductive resin composition are required to have lower resistance.

  In response to such a demand, for example, a conductive composition containing flaky silver-coated particles, a thermosetting resin, and a curing agent has been proposed (see Patent Document 1).

WO2012 / 118061A1

  However, today, under the circumstances where the performance of electronic devices is increasing, it is required to have a lower resistance than ever before. The conventional conductive resin composition still has room for improvement in terms of dispersibility as a composition.

  Accordingly, an object of the present invention is to provide a conductive resin composition that has a lower resistance than before, excellent conductivity, and excellent dispersibility as a composition.

  As a result of intensive studies to solve the above problems, the present inventors have added conductive powder, thermoplastic resin, bisphenol type epoxy resin, latent curing agent, boron compound, silica, and solvent as essential components. And it discovered that the said subject could be solved by the dispersibility as a composition becoming favorable, without impairing low resistance, and came to complete this invention.

  That is, the conductive resin composition of the present invention comprises (A) conductive powder, (B) thermoplastic resin, (C) bisphenol type epoxy resin, (D) latent curing agent, (E) boron compound, (F) It contains silica and (G) a solvent.

  In the conductive resin composition of the present invention, the (C) bisphenol type epoxy resin is preferably at least one of a mixture of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin and a bisphenol AD type epoxy resin. .

  In the conductive resin composition of the present invention, the amount of the (F) silica is preferably 10% by mass or less based on the total amount of the composition.

  In the conductive resin composition of the present invention, the thermoplastic resin (B) preferably has a weight average molecular weight of 5000 or more.

  In the conductive resin composition of the present invention, the (D) latent curing agent is a reaction of at least one imidazole curing agent of 2-ethyl-4-methylimidazole and 2-methylimidazole with a liquid epoxy compound. It is preferable that it is a thing.

  According to the present invention, it is possible to provide a conductive resin composition that has lower resistance than before, excellent conductivity, and excellent dispersibility as a composition. In particular, according to the present invention, a conductive resin composition having excellent dispersibility as a composition can be obtained even when a powder additive such as a boron compound is blended.

Hereinafter, embodiments of the present invention will be described in detail.
The conductive resin composition of the present invention comprises (A) conductive powder, (B) thermoplastic resin, (C) bisphenol type epoxy resin, (D) latent curing agent, (E) boron compound, (F) silica, And (G) a solvent. Thereby, it can be set as the conductive resin composition which is excellent in electroconductivity as it is low resistance more than before, and is excellent also in the dispersibility as a composition. Moreover, even if it mix | blends powder additives, such as a boron compound, it can be set as the conductive resin composition excellent in the dispersibility as a composition.

  Next, each component of the conductive resin composition of the present invention will be described.

[(A) Conductive powder]
The conductive resin composition of the present invention contains (A) conductive powder. The conductive powder is a component for imparting conductivity to, for example, an electrode or an electric wiring formed by the conductive resin composition of the present invention. As the conductive powder, at least one powder selected from gold, silver, copper, nickel, tin and alloys containing these is used, and among them, silver powder is preferably used.

  As the shape of the silver powder as the conductive powder, for example, a spherical shape, a flake shape, or a chain shape can be used. Here, the flake shape includes a flat plate shape, a thin rectangular parallelepiped shape, a flake shape, and a scale shape, and means a shape having an aspect ratio (average major axis / average thickness) larger than 1.5. The aspect ratio can be obtained by (average major axis L / average thickness T). Here, the “average major axis L” and the “average thickness T” indicate the average major axis and average thickness of 30 flaky silver powders measured with a scanning electron microscope. In addition, the chain shape specifically includes aggregated silver powder or silver particles branched into branches, that is, dendritic silver powder.

The conductive powder (A) preferably has an average particle diameter (D ₅₀ ) measured by a laser diffraction / scattering particle size distribution measurement method in the range of 0.1 to 10 μm, more preferably in the range of 0.5 to 6 μm. When the average particle size is within this range, the contact resistance is suppressed and the resistance value is lowered, which is preferable. Further, when a conductor pattern is printed using a mesh screen plate, clogging of the screen is suppressed, workability is improved, and fine wiring can be formed, which is preferable.

  Such conductive powders may be used alone or in combination of two or more. (A) It is preferable that the compounding quantity of electroconductive powder shall be 55-90 mass% with respect to the composition whole quantity, More preferably, it is 65-85 mass%. The reason for this is that when the blending amount is within this range, the resistance value becomes low, clogging of the screen is suppressed, and workability is improved.

[(B) Thermoplastic resin]
The conductive resin composition of the present invention contains (B) a thermoplastic resin. (B) The thermoplastic resin is excellent in film forming properties and has a function of promoting contact between conductive particles even when a large amount of conductive powder is blended in the composition. As a result, the resistance of the conductor can be reduced by blending the thermoplastic resin.

  In the present invention, (B) thermoplastic resin includes polyester resin, phenoxy resin, butyral resin, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, A polycarbonate resin, a thermoplastic polyimide resin, a polyamide resin such as 6-nylon or 6,6 nylon, an acrylic resin, a polyamideimide resin, a fluororesin, or a partially modified product of these resins can be used. Especially, in this invention, it is preferable to use a phenoxy resin and a butyral resin.

  Examples of commercially available phenoxy resins include YP-50, YP-70 (manufactured by Nippon Steel Chemical Co., Ltd.), PKHC, PKHH, PKHJ and the like (manufactured by InChem).

  Such a thermoplastic resin may be used individually by 1 type, and may be used in combination of 2 or more type. (B) The thermoplastic resin preferably has a weight average molecular weight (Mw) of 5000 or more. More preferably, it is the range of 8,000-60,000. In addition, a weight average molecular weight (Mw) is the value of standard polystyrene conversion measured by gel permeation chromatography (GPC).

  (B) It is preferable that the compounding quantity of a thermoplastic resin shall be 1-30 mass% with respect to the composition whole quantity, More preferably, it is 2-10 mass%. This is because if the blending amount is within this range, the film forming property is good, the contact between the conductive particles is promoted, and the resistance value is lowered.

[(C) Bisphenol type epoxy resin]
The conductive resin composition of the present invention contains (C) a bisphenol type epoxy resin. (C) As the bisphenol type epoxy resin, known and commonly used bisphenol type epoxy resins can be used, but bisphenol A type epoxy resins, bisphenol F type epoxy resins, a mixture of bisphenol A type epoxy resins and bisphenol F type epoxy resins, It is preferable to use a bisphenol AD type (bisphenol E type) epoxy resin. Among these, a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin and bisphenol AD type epoxy resin are particularly preferable. In the case of a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, the preferred ratio of bisphenol A type epoxy resin and bisphenol F type epoxy resin is 8: 2 to 2: 8, more preferably 7 : 3 to 3: 7. When the ratio of the bisphenol A type epoxy resin to the bisphenol F type epoxy resin is 8: 2 to 2: 8, it is more excellent in terms of suppressing crystallization of the resin. These bisphenol type epoxy resins may be used alone or in combination of two or more.

  (C) It is preferable that the compounding quantity of a bisphenol type epoxy resin shall be 0.1-10 mass% with respect to the composition whole quantity, More preferably, it is 0.5-5 mass%. It is preferable for the amount of the bisphenol-type epoxy resin to be within this range since the strength, adhesion, water resistance, weather resistance, etc. of the resulting cured film will be good. Moreover, (B) Since the effect which accelerates | stimulates the contact between the electrically-conductive particles by the drying shrinkage of a thermoplastic resin becomes favorable, it is preferable.

[(D) Latent curing agent]
The conductive resin composition of the present invention contains (D) a latent curing agent. (D) As the latent curing agent, a known and conventional latent curing agent can be used. For example, an adduct system such as an adduct obtained by reacting an amine compound such as an imidazole compound and an epoxy compound, or a resin coating is used. Examples of the microcapsules include a composition in which microcapsules of an imidazole compound are dispersed in a liquid epoxy compound. Among these, as the latent curing agent, an adduct system is preferable. In particular, a reaction product of at least one imidazole curing agent of 2-ethyl-4-methylimidazole and 2-methylimidazole with a liquid epoxy compound, for example, Shikoku Kasei Kogyo Co., Ltd. Cure Duct P-0505 is preferably used.

  These latent curing agents are activated when the adduct dissolves or the coating resin dissolves at a certain temperature or higher, and the curing reaction proceeds. For example, latent curing that can be activated at 60 to 130 ° C. Agents. Such a latent curing agent is stable without functioning as an epoxy resin curing agent at less than 60 ° C., but functions as a curing agent at 60 ° C. or more and 130 ° C. or less. A latent curing agent that can be activated at 60 ° C. to 130 ° C. is excellent in storage stability at room temperature in a mixed system with an epoxy resin, and quickly cures under a temperature condition of 60 ° C. or more that functions as a curing agent. Is.

  Such latent curing agents may be used alone or in combination of two or more. (D) It is preferable that the compounding quantity of a latent hardening | curing agent shall be 0.05-2.0 mass% with respect to the composition whole quantity, More preferably, it is 0.1-1.0 mass%. It is preferable that the blending amount of the latent curing agent is within this range because an appropriate curing reaction can be performed.

[(E) Boron compound]
The conductive resin composition of the present invention contains (E) a boron compound. The boron compound functions as a stabilizer to suppress the surface activity of the curing component and further improve the storage stability. (E) As a boron compound, a well-known and usual thing can be used, For example, a borate ester compound etc. are mentioned.

  (E) It is preferable that the compounding quantity of a boron compound shall be 0.01-0.5 mass% with respect to the composition whole quantity, More preferably, it is 0.02-0.2 mass%. It is preferable for the compounding amount of the boron compound to be within this range because the thermosetting reactivity is not impaired and the storage stability is excellent.

[(F) Silica]
The conductive resin composition of the present invention contains (F) silica. Silica is a component that contributes to the dispersibility of the conductive resin composition of the present invention. Therefore, in the present invention, by containing (F) silica in combination with the components (A) to (E) and the component (G) shown below, the conductivity is lower than ever and excellent in conductivity. A resin composition can be obtained. In particular, by containing (F) silica in a blending amount within a specific range shown below, the dispersibility as a composition can be improved even when powder additives such as boron compounds are blended.

  Examples of (F) silica include fused silica, spherical silica, amorphous silica, crystalline silica, fine powder silica, and the like, and fine powder silica is particularly preferable.

(F) As the silica, either hydrophilic silica that is not surface-treated or surface-treated silica can be used. Examples of the surface treatment method for the surface-treated silica include hydrophobization treatment (chemical treatment with silane, siloxane, hexamethyldisilazane, silicone oil, etc.) and the like.
As the surface treatment agent, silane-based, siloxane-based, titanate-based, aluminate-based and zircoaluminate-based coupling agents, silicone oil, and the like can be used. Of these, silane coupling agents and silicone oils are preferred. Examples of such silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N- (2-aminomethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-amino. Propyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxy (Cyclohexyl) ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane and the like can be mentioned, and these can be used alone or in combination. These surface treatment agents may be added at the time of preparing the composition.

Such silica may be used individually by 1 type, and may be used in combination of 2 or more type. The specific surface area of (F) silica measured by the BET method is preferably 50 to 300 m ² / g, more preferably 50 to 260 m ² / g.

  (F) It is preferable that the compounding quantity of a silica is 10 mass% or less with respect to the composition whole quantity. More preferably, it is more than 0 and 8.0% by mass or less, more preferably more than 0 and 6.0% by mass or less. When the amount of silica is within this range, the dispersibility as the composition is improved without impairing the low resistance, which is preferable.

[(G) Solvent]
The conductive resin composition of the present invention contains (G) a solvent. (G) As a solvent, a well-known usual solvent can be used. Specific examples of the solvent include, for example, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methylcellosolve, carbitol, methylcarbitol, butylcarbitol, propylene Glycol ethers such as glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, ethyl carbitol acetate, Acetic esters such as butyl carbitol acetate and propylene glycol monomethyl ether acetate; ethanol, propano Alcohols such as ethylene, propylene glycol, terpineol (α-terpineol), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; aliphatic hydrocarbons such as octane and decane; petroleum ether Petroleum solvents such as petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha can be used, and these can be used alone or in combination of two or more.

(Epoxy resins other than bisphenol type epoxy resins)
The conductive resin composition of the present invention can contain an epoxy resin other than a bisphenol-type epoxy resin. Examples of such an epoxy resin include polyfunctional epoxy resins having two or more epoxy groups in one molecule, and generally used epoxy resins can be used. For example, phenol novolac type and resole novolac Novolak type epoxy resins such as molds, amino epoxy resins and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The amount of the epoxy resin other than the bisphenol type epoxy resin is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, based on the total amount of the composition.

  In the present invention, a known and commonly used additive can be further blended. Examples of the additive include 3-glycidoxypropyltrimethoxysilane.

  The conductive resin composition of the present invention can be suitably used for electrodes for electronic parts such as printed boards. Moreover, the conductive resin composition of the present invention is also suitable for a conductor formed on a heat-sensitive substrate such as a film substrate such as a polarizing plate contained in a liquid crystal panel member.

  The conductive resin composition of the present invention can be suitably used for forming a conductor. The conductor is obtained, for example, by applying the above-described conductive resin composition on a substrate and thermosetting it.

  The conductor may be in various shapes depending on the application used. Examples of the conductor are a conductor circuit and wiring.

  Examples of the coating method include gravure printing, offset printing, screen printing, coating with a dispenser, and the like. When a fine circuit is formed, screen printing is preferable.

  As thermosetting conditions, it can process in 60-200 degreeC and 3-120 minutes, for example.

  Examples of the base material include glass, paper-phenol resin, paper-epoxy resin, glass cloth-epoxy resin, glass-polyimide, glass cloth / nonwoven fabric-epoxy resin, glass cloth / paper-epoxy resin, synthetic fiber-epoxy resin. , Copper-clad laminates of all grades (FR-4 etc.) using composite materials such as fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate ester, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, etc. Sheets or films made of plastic such as polyester, polyimide, polyphenylene sulfide, polyamide, etc., sheets or films made of crosslinked rubber such as urethane, silicone rubber, acrylic rubber, butadiene rubber, polyester-based, polyurethane Tan, polyolefin, styrenic block copolymer-based sheet or film or the like made of thermoplastic elastomers, and the like.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following, “part” and “%” are based on mass unless otherwise specified.

(Preparation of conductive resin compositions of Examples and Comparative Examples)
The components shown in Table 1 and Table 2 below were blended in the proportions (parts by mass) listed in the table, premixed with a stirrer, dispersed with a three-roll mill, and kneaded to prepare compositions. did. The compounding quantity in a table | surface shows a mass part.

＊１：フレーク状銀粉末、平均粒径（Ｄ_５０）４〜５μｍ
＊２：球状銀粉末、平均粒径（Ｄ_５０）１〜３μｍ
＊３：フェノキシ樹脂（ＩｎＣｈｅｍ社製ＰＫＨＣ）、Ｍｗ＝４３０００
＊４：ブチラール樹脂（積水化学工業社製エスレックＢＬ−１０）、Ｍｗ＝１５０００
＊５：ビスフェノールＡＤ型エポキシ樹脂（プリンテック社製Ｒ７１０）
＊６：ビスフェノールＡ型エポキシ樹脂とビスフェノールＦ型エポキシ樹脂の
混合物（５：５）（新日鐵化学社製エポトートＺＸ−１０５９）
＊７：表面処理なし（親水性）微粉シリカ（日本アエロジル社製アエロジル２００）、比表面積２００±２５ｍ^２／ｇ
＊８：疎水化処理された（シリコーンオイル処理）微粉シリカ（日本アエロジル社製アエロジルＲＹ２００）、比表面積１００±２０ｍ^２／ｇ
＊９：四国化成工業社製キュアダクトＰ−０５０５
＊１０：ホウ酸エステル化合物（四国化成工業社製キュアダクトＬ−０７Ｎ）
＊１１：エチルカルビトールアセテート
＊１２：２，２，４−トリメチル−１，３−ペンタンジオールモノイソブチレート
＊１３：住友化学社製スミエポキシＥＬＭ−１００、エポキシ当量１１０
＊１４：３−グリシドキシプロピルトリメトキシシラン（東レ・ダウコーニング社製ＯＦＳ−６０４０）

* 1: Flaky silver powder, average particle size (D ₅₀ ) 4-5 μm
* 2: Spherical silver powder, average particle size (D ₅₀ ) 1 to 3 μm
* 3: Phenoxy resin (PKHC manufactured by InChem), Mw = 43000
* 4: Butyral resin (Surek Chemical Co., Ltd. ESREC BL-10), Mw = 15000
* 5: Bisphenol AD type epoxy resin (R710 manufactured by Printec)
* 6: Mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin (5: 5) (Epototo ZX-1059 manufactured by Nippon Steel Chemical Co., Ltd.)
* 7: No surface treatment (hydrophilic) fine silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.), specific surface area 200 ± 25 m ² / g
* 8: Hydrophobized (silicone oil treated) fine silica (Aerosil RY200 manufactured by Nippon Aerosil Co., Ltd.), specific surface area 100 ± 20 m ² / g
* 9: Cure duct P-0505 manufactured by Shikoku Kasei Kogyo Co., Ltd.
* 10: Boric acid ester compound (Cure Duct L-07N manufactured by Shikoku Kasei Kogyo Co., Ltd.)
* 11: Ethyl carbitol acetate * 12: 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate * 13: Sumiepoxy ELM-100 manufactured by Sumitomo Chemical Co., epoxy equivalent 110
* 14: 3-Glycidoxypropyltrimethoxysilane (OFS-6040 manufactured by Dow Corning Toray)

  Each composition of the obtained Examples and Comparative Examples was evaluated according to the following. The results are shown in the above table.

(Dispersity)
The dispersion degree by the linear method was evaluated by using each of the conductive resin compositions of Examples and Comparative Examples using a grind gauge having a width of 90 mm, a length of 240 mm, and a maximum depth of 50 μm in accordance with JIS K5101 and JIS K5600. . The obtained results are shown in Tables 1 and 2 above.

(Volume resistivity)
Each of the conductive resin compositions of Examples and Comparative Examples was printed with an evaluation pattern having a width of 1 mm and a length of 40 mm on a slide glass (manufactured by Matsunami Glass Industry Co., Ltd., trade name: slide glass S7213) by screen printing. It hardened | cured on conditions for 30 minutes at 0 degreeC, and produced the pattern of the conductive resin composition. The line width, line length, and thickness of the prepared pattern were measured, and volume resistivity was calculated to evaluate conductivity. The obtained results are shown in Tables 1 and 2 above.

  As shown in Tables 1 and 2 above, the conductive resin compositions of Examples 1 to 6 containing conductive powder, thermoplastic resin, bisphenol-type epoxy resin, latent curing agent, boron compound, silica, and solvent as essential components. It can be seen that the product is low in resistance and excellent in conductivity as compared with the conductive resin compositions of Comparative Examples 1 and 2 that do not contain silica, and is excellent in dispersibility as a composition.

Claims (5)

  (A) Conductive powder, (B) thermoplastic resin, (C) bisphenol type epoxy resin, (D) latent curing agent, (E) boron compound, (F) silica, and (G) solvent A conductive resin composition.   2. The conductive resin composition according to claim 1, wherein the (C) bisphenol type epoxy resin is at least one of a mixture of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin and a bisphenol AD type epoxy resin.   The conductive resin composition according to claim 1 or 2, wherein the amount of the (F) silica is 10% by mass or less based on the total amount of the composition.   The conductive resin composition according to claim 1, wherein the thermoplastic resin (B) has a weight average molecular weight of 5000 or more.   The (D) latent curing agent is a reaction product of at least one imidazole curing agent of 2-ethyl-4-methylimidazole and 2-methylimidazole and a liquid epoxy compound. The conductive resin composition as described in any one.