JP2004176005A

JP2004176005A - Conductive elastomer composition and production method thereof

Info

Publication number: JP2004176005A
Application number: JP2002346630A
Authority: JP
Inventors: Shiro Tanami; 史郎田波; Norie Kazaoka; 紀江風岡; Hiromichi Endo; 裕理遠藤
Original assignee: Kinugawa Rubber Industrial Co Ltd
Current assignee: Kinugawa Rubber Industrial Co Ltd
Priority date: 2002-11-29
Filing date: 2002-11-29
Publication date: 2004-06-24

Abstract

<P>PROBLEM TO BE SOLVED: To attain the improvement of an electroconductive elastomer composition in its mechanical properties (hardness and tensile strength), conductivity, conductive material retention and corrosion resistance. <P>SOLUTION: Silicone rubber and a hardening agent are combined with conductive materials comprising a metal powder having arborescent shapes and a metal powder of flaky shapes and the resultant mixture is kneaded and crosslinked to obtain a rubber compound. The resultant compound is dissolved in an organic solvent including saturated hydrocarbons (to be converted into ink). Then, the dissolved solution is applied on the surface of, for example, a heat-resistant film as the thickness of the coating film is adjusted, then dried and cured (for example, cured at elevated temperature by drying) whereby a conductive elastomer body composition is formed on the surface of the supported body in a desired thickness. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、導電性弾性体組成物およびその製造方法に関するものであり、例えば電気機器等の電流の接点部分，静電気対策部材，レーザー式プリンタ用の電極，電子機器の電磁波シールド部材，コネクタ類のシール部材等に用いられるものである。
【０００２】
【従来の技術】
導電性材料（カーボンブラック，金属紛等の導電性材料），高分子弾性材料（ゴム等の高分子材料）等から成る組成物（導電性弾性体組成物；以下、導電弾性物と称する）は種々の技術分野で利用され、例えば電気機器（例えば、家庭用コンピュータ，テレビ）等のキーボードやリモートコントロールにおける電流の接点部分、ＯＡフロア―，工場床材料における静電気対策部材、レーザー式プリンタ用の帯電，現像ローラー等の電極、電子機器の外部電波防止用の電磁波シールド部材，コネクタ類に用いられるシール部材等に利用されている。
【０００３】
前記導電弾性物には種々の高分子弾性材料が用いられているが、特に加工性の優れたシリコーンゴムが多用されている。また、導電性材料においても種々の材料を用いることができるが、例えば電磁波シールド部材の場合は低抵抗の導電弾性物を用いる必要があるため、ニッケル紛，銅紛，銀紛，金紛，ハンダ等の導電性の高い金属粉体が多用されている。
【０００４】
前記のようにシリコーンゴムと金属粉体とを用いて成る導電弾性物は、十分な導電性（体積固有抵抗値が低いこと），機械的特性（例えば、強度，伸縮性），導電材保持性（金属粉体の脱落が無いこと），耐腐食性（例えば、高温・高湿環境下による抵抗値変化が無いこと）等を要求されるが、低抵抗の導電弾性物としては電気伝導度の大きい銀をポリマーに添加し混合して成るものが知られており、例えば付加反応硬化型，縮合反応硬化型，パーオキサイド加硫硬化型の導電弾性物がある。
【０００５】
例えば、特開２００１−１７２５０６号公報，特開２００２−６０６２５号公報，特開２００２−２１２４２６号公報では、平均組成式がＲ^１ _ｎＳｉＯ_{（４−ｎ）／２}で示され分子中に脂肪族不飽和基を少なくとも１個有するオルガノポリシロキサン（組成式中のＲ^１は、同一または異種の非置換または置換１価の炭化水素基）に対し、金属粉体（例えば、銀粉）または表面に金属メッキ層を有する紛体（例えば、基材粒子表面に銀メッキ層を形成した粉体），所定量の硬化剤（オルガノポリシロキサンを硬化させ得る量の硬化剤）を加え、例えばオープンロール，ニーダー，インターナルミキサー等の混練分散装置により混合・分散して成る導電弾性物が開示されている。
【０００６】
前記の表面に金属メッキ層を有する紛体（以下、メッキ粉体と称する）は、銀粉等の金属粉体よりもシリコーンゴムに対する分散性が良好で、高い導電性が得られることが記載されている。また、前記の金属メッキ層と基材粒子との間の結合力を高めるために、基材粒子表面に対して例えばエポキシ基またはグリシジル基を有する有機珪素化合物の薄膜を形成してから被覆することが記載されている。さらに、前記の金属粉体としては、その形状が薄片状（Ｆｌａｋｅ）やブドウ状等の種々のものを用いても良いが、各粉体同志の凝集を抑える点で球状のものが好ましいことが記載されている。
【０００７】
【特許文献１】
特開２００１−１７２５０６号公報（段落［０００８］〜［００１３］，［００１９］）。
【０００８】
【特許文献２】
特開２００２−６０６２５号公報（段落［０００７］〜［００１１］，［００２０］）。
【０００９】
【特許文献３】
特開２００２−２１２４２６号公報（段落［０００７］〜［００１４］）。
【００１０】
【発明が解決しようとする課題】
しかしながら、前記のようにメッキ粉体をシリコーンゴムに混合した導電弾性物の場合、その混合の際にメッキ粉体から金属メッキ層が剥離し易いため、その導電弾性物の体積固有抵抗値の上昇を招く問題が生じる。
【００１１】
また、前記のように導電性材料として金属粉体を用いた場合、たとえ金属粉体の形状が球状であっても、前記メッキ粉体を用いた場合と同様に導電弾性物の低抵抗化を図るには多量の金属粉体を必要とするため、その金属粉体の使用量の増加に伴って導電弾性物が過剰に硬化して脆弱になると共に伸縮性，導電材保持性が低下してしまう。
【００１２】
さらに、前記のような導電弾性物において所望の形状に成型する場合、一般的にはコンプレッション成型法，押出し成型法，カレンダー成型法，インフレーション加工法等の製造方法が適用されているが、これらの製造方法では薄膜（例えば、厚さ０．５ｍｍ以下の薄膜）を形成することが困難である。
【００１３】
本発明は前記課題に基づいてなされたものであり、導電弾性物（例えば、薄膜の導電弾性物）において低抵抗化を図ると共に導電性材料の脱落を抑制し、機械的特性，耐腐食性を良好にできる導電性弾性体組成物およびその製造方法を提供することにある。
【００１４】
【課題を解決するための手段】
本発明は前記の課題の解決を図るものであり、請求項１に記載の発明は、少なくともシリコーンゴム（例えば、平均組成式がＲ^１ _ｎＳｉＯ_{（４−ｎ）／２}で示され分子中に脂肪族不飽和基を少なくとも１個有するシリコーンゴム（組成式中のＲ^１は、同一または異種の非置換または置換１価の炭化水素基）），導電性材料，硬化剤（例えば、ポリハイドロジェンシロキサン，白金触媒）から成る導電性弾性体組成物において、前記導電性材料は、形状が薄片状の金属粉体と形状が樹枝状の金属粉体とを含んだことを特徴とする。
【００１５】
請求項２に記載の発明は、前記金属粉体が銀（銀粉）から成ることを特徴とする。
【００１６】
請求項３に記載の発明は、少なくとも１個のビニル基またはアルケニル基を有する分子構造の有機珪素化合物が配合されたことを特徴とする。
【００１７】
請求項４に記載の発明は、導電性弾性体組成物の製造方法において、シリコーンゴム（例えば、平均組成式がＲ^１ _ｎＳｉＯ_{（４−ｎ）／２}で示され分子中に脂肪族不飽和基を少なくとも１個有するシリコーンゴム（組成式中のＲ^１は、同一または異種の非置換または置換１価の炭化水素基）），導電性材料（例えば、請求項１乃至３に示す金属粉体），硬化剤（例えば、ポリハイドロジェンシロキサン，白金触媒）を混練（または、シリコーンゴム，導電性材料，硬化剤，有機珪素化合物（例えば、請求項３に示す有機珪素化合物）を混練）して架橋し、その架橋物を有機溶剤によりインキ化してから被支持体表面（例えば、薄板の一端面側に敷設された耐熱性フィルム表面）に塗布した後、乾燥し硬化（例えば、乾燥よりも高温で硬化）させて導電性弾性体組成物を得、前記有機溶剤には飽和炭化水素化合物を用いることを特徴とする。
【００１８】
導電弾性物を製造する方法として、一般的には例えばコンプレッション成型法，押出し成型法，カレンダー成型法が適用されているが、前記の各方法では、例えば厚さ０．５ｍｍ以下の薄膜の導電弾性物を作製することが困難である（例えばカレンダー成型法では、カレンダーロールから薄膜を剥離することが困難）。また、薄膜の樹脂組成物の製造方法ではインフレーション加工法が適用されているが、導電弾性物の場合には架橋前の強度が低すぎるため適用できない。
【００１９】
一方、請求項４に記載の発明によれば、シリコーンゴム，導電性材料等を配合して得た架橋物を有機溶剤によりインキ化してから被支持体表面に塗布した後、その塗布厚さを調整してから硬化させることにより、容易に薄膜（例えば、０．０１〜０．５ｍｍ）の導電弾性物を作製することができる。
【００２０】
なお、前記有機溶剤には、例えば芳香族系（好ましくは、トルエン，キシレン，トリメチルベンゼン等），オレフィン系（好ましくは、石油エーテル，ソルベントナフサ，ミネラルスピリット，ケロシン，ソルベッツ，ノルマルヘキサン，ノルマルペンタン，イソオクタン，イソヘプタン等），エステル系（好ましくは、酢酸エチル，酢酸ブチル，酢酸イソブチル，酢酸アミル，酢酸エチル，酢酸イソブチル，吉草酸イソブチル，乳酸エチル，乳酸プロピル，ぎ酸エチル，ぎ酸ブチル，ぎ酸プロピル等），ケトン系（好ましくは、アセトン，メチルエチルケトン，ジメチルケトン，ジエチルケトン等）の溶剤や、これら各溶剤の混合物を用いることができる。
【００２１】
また、前記被支持体には耐熱性を有する部材が用いられ、例えばポリエチレンテレフタレート（以下、ＰＥＴと称する）フィルム，ＴＰＸ（ポリメチルペンテナン）フィルム，ポリエチレンナフタレートフィルム，ポリエーテルエーテルケトンフィルム，ポリイミドフィルム，ポリアリレートフィルム等が挙げられる。
【００２２】
さらに、架橋物を有機溶剤によりインキ化してから被支持体表面に塗布する場合、一般的なロールコータ法（例えば、リバースコータ法，ドクターブレードコータ法，グラビアコータ法，コンマコータ法等），バーコータ法，スクリーン印刷法等を適用することができる。前記スクリーン印刷法においては、例えばナイロンメッシュ版により作製されたスクリーン版（メッシュ１００または７５にてレジスト厚みが例えば３０μｍに調整されたスクリーン版）を用い、前記のインキ化されたものを被支持体表面に印刷することにより、薄膜の導電弾性物が得られる。
【００２３】
さらにまた、請求項４に記載の発明は、前記のような導電弾性物の薄膜化に限定されるものではなく、他の高分子材料から成る組成物において薄膜化する場合にも適用することが可能である。
【００２４】
加えて、前記樹枝状の金属粉体は、例えば未精製の金属粗鋼を電解質溶液中で電解精製する電解法（Ｅｌｅｃｔｒｏｌｙｚｉｎｇ）により得ることができる。前記薄片状の金属粉体は、例えば精製した金属紛をスタンプミル等で薄片状にするスタンプ法（Ｓｔａｍｐｉｎｇ）や、金属イオン溶液（イオン化により金属が溶解された溶液）中に還元剤を添加して精製された金属を粉砕しフレーク化する化学還元法（ＣｈｅｍｉｃａｌＲｅｄｕｃｔｉｏｎ）により得ることができる。球状の金属粉体は、例えば未精製の金属粗鋼を溶解し空気中（または水中）で噴霧して粉状体を取り出すアトマイズ法（Ａｔｏｍｉｚａｔｉｏｎ）により得ることができる。
【００２５】
【発明の実施の形態】
以下、本発明の実施の形態における導電性弾性体組成物およびその製造方法を図面等に基づいて詳細に説明する。
【００２６】
本実施の形態では、平均組成式がＲ^１ _ｎＳｉＯ_{（４−ｎ）／２}で示され分子中に脂肪族不飽和基を少なくとも１個有するシリコーンゴム（組成式中のＲ^１は、同一または異種の非置換または置換１価の炭化水素基）に対して、粒子の形状が異なる複数の金属粉体（またはメッキ粉体），硬化剤を所定量配合、または前記シリコーンゴム，金属粉体，硬化剤の他に有機珪素化合物を所定量配合し、混練および硬化することにより導電弾性物の試料を作製して、それぞれ後述する各実施例により特性変化を調べ、導電弾性物の機械的特性（硬度，引張強度），導電性，導電材保持性，耐腐食性を向上させることを検討した。また、前記の導電弾性物において薄膜化が可能な製造方法においても検討した。
【００２７】
［実施例１；金属粉体の形状の違いによる特性変化］
シリコーンゴムとして平均組成式がＲ^１ _ｎＳｉＯ_{（４−ｎ）／２}で示され分子中に脂肪族不飽和基を少なくとも１個有するオルガノポリシロキサンを１００部用い、そのオルガノポリシロキサンを容器内にてロールにより撹拌しながら硬化剤としてポリハイドロジェンシロキサンを２．７部，白金触媒を０．１部配合した後、さらに金属粉体として形状が樹枝状，薄片状，または球状の銀粉（本実施の形態では平均粒子径が約１μｍ〜５０μｍの銀粉）を２００〜４００部配合し、混練および架橋することにより下記表１に示すゴムのコンパウンドＧ１〜Ｇ９を得た。なお、下記表２は前記オルガノポリシロキサン，銀粉，ポリハイドロジェンポリシロキサン，白金触媒のメーカー等を示すものである。
【００２８】
【表１】

【００２９】
【表２】

【００３０】
そして、前記の各コンパウンドＧ１〜Ｇ９を飽和炭化水素化合物から成る有機溶剤（例えば、芳香族系，オレフィン系，エステル系，ケトン系の有機溶剤）でそれぞれインキ化（溶解）して、それらインキ化された各溶液を図１に示すよう薄板１１の一端面側に敷設された耐熱性フィルム（例えば、ＰＥＴから成る薄膜）１２の表面に対して塗布し、ガラス棒１３を使用（例えば、図１の矢印方向に掃引）して流延した。
【００３１】
その後、前記の流延された溶液（図１中の符号１４）を所定条件で乾燥（例えば、温度４０℃，３０分間、または温度６０℃，２０分間で乾燥）してから、さらに前記乾燥温度よりも高い温度にて硬化（例えば、温度１８０℃，２０分間、または温度２００℃，１５分間で硬化）させることにより、前記耐熱性フィルム１２上に薄膜（厚さ０．１ｍｍの薄膜）の導電弾性物Ｓ１〜Ｓ９をそれぞれ作製した。
【００３２】
なお、前記の耐熱性フィルム１２が活性水素（化学的構造上の活性水素）を有する場合、前記の各導電弾性物Ｓ１〜Ｓ９を耐熱性フィルム１２から剥離し易くする必要があるため、前記活性水素による活性度合いに応じて例えば前記耐熱性フィルム１２表面を予め離形処理（例えば、フッ素を用いた離形処理）してから、図１に示すように導電弾性物Ｓ１〜Ｓ９を作製しても良い。
【００３３】
また、前記の耐熱性フィルム１２上に塗布された各コンパウンドＧ１〜Ｇ９の溶液を流延させる際、前記耐熱性フィルム１２とガラス棒１３との間に所定厚さのスペーサ（例えば、ＰＥＴから成るスペーサ；図示省略）を介在させるが、そのスペーサの厚さ（すなわち、耐熱性フィルム１２とガラス棒１３との間の距離）を種々変化させて導電弾性物を作成したところ、下記表３に示すように極めて薄膜（例えば、約０．５〜０．００１ｍｍの薄膜）の導電弾性物が得られることを確認できた。
【００３４】
【表３】

【００３５】
次に、前記の導電弾性物Ｓ１〜Ｓ９において、硬度（ＪＩＳのＫ６２５３），引張強度（ＪＩＳのＫ６２５２），導電性（体積固有抵抗値；ＪＩＳのＫ７１９４）をそれぞれ測定すると共に、図２，３に示す方法（詳細を後述する）により銀粉の脱落の有無（導電材保持性試験），腐食による抵抗値変化（耐腐食性試験）をそれぞれ調べ、それら結果を後記の表４に示した。なお、本実施の形態では、前記体積固有抵抗値，導電材保持性，耐腐食性の目標値を、それぞれ５．０×１０^−２Ω・ｃｍ以下，脱落した銀粉が３０個以下，１Ω以下に設定した。
【００３６】
図２は導電材保持性試験の概略説明図であり、まず試料２１（導電弾性物Ｓ１〜Ｓ９）の一端面側における一部の領域（１０ｍｍ×１０ｍｍの領域）に対して、カッターナイフを擦りつけることにより長さ１０ｍｍの線条痕２２をそれぞれ１ｍｍ間隔で形成し、それら線条痕を覆うようにセロテープ（ＮＩＣＨＩＢＡＮ社の登録商標；以下省略）２３の粘着面を貼り付けた。そして、前記試料２１の一端面側にて、直径３０ｍｍの円柱状のローラ２４を約４．９Ｎ加重しながら回転（一方向に１回転）させた後、前記セロテープ２３を試料２１から剥離し、そのセロテープに付着した銀粉（カッターナイフの擦りつけにより脱落した銀粉）の個数を顕微鏡により調べた。
【００３７】
図３は耐腐食性試験の概略説明図を示すものであり、まず２つのプローブ３１ａ，３１ｂを有するテスター３１を用い、そのプローブ３１ａ，３１ｂを互いに３ｃｍの間隔を隔てて矩形薄膜状（０．８ｍｍ×５０ｍｍ×５０ｍｍ）の試料（導電弾性物Ｓ１〜Ｓ９）３２上に当接して抵抗（以下、腐食前抵抗と称する）を測定した後、前記試料３２を温度７０℃，相対湿度７０％ｒｈの雰囲気下に５００時間曝してから再度テスター３１を用いて抵抗（以下、腐食後抵抗と称する）を測定し、前記腐食前抵抗と腐食後抵抗との差を算出した。
【００３８】
【表４】

【００３９】
前記表４に示すように、導電弾性物Ｓ１〜Ｓ９は、それぞれ銀粉の配合量の増加に伴って体積固有抵抗値が向上したが、銀粉の配合量が多すぎると高硬度になり引張強度が低下してしまったことを確認できた（例えば、導電弾性物Ｓ３，Ｓ６，Ｓ９）。また、形状が球状の銀粉を用いた導電弾性物Ｓ７〜Ｓ９は、銀粉の配合量を多くすると十分な導電性が得られる替わりに導電材保持性は低下し、銀粉の配合量を少なくすると十分な導電材保持性が得られる替わりに導電性は低下してしまったことを確認できた。
【００４０】
一方、形状が樹枝状の銀粉を用いた導電弾性物Ｓ１〜Ｓ３は、十分な導電材保持性，耐腐食性は得られなかったが、良好な導電性（目標値を達成した導電性）が得られたことを確認できた。また、形状が薄片状の銀粉を用いた導電弾性物Ｓ４〜Ｓ６は、導電弾性物と同様の導電性が得られると共に、十分な配合量の銀粉を用いた場合（例えば、導電弾性物Ｓ５，Ｓ６）には良好な耐腐食性（目標値を達成した耐腐食性）が得られたことを確認できた。
【００４１】
［実施例２；金属粉体の形状の組み合わせよる特性変化］
前記実施例１と同様にオルガノポリシロキサン１００部にポリハイドロジェンシロキサンを２．７部，白金触媒を０．１部配合した後、さらに形状が樹枝状，薄片状，球状の銀粉のうち何れか２つを種々の割合で混合して成る金属粉体を３００部配合し、混練および架橋することにより下記表５に示すゴムのコンパウンドＧ１０〜Ｇ１３を得た。
【００４２】
【表５】

【００４３】
そして、実施例１と同様の方法により、前記の各コンパウンドＧ１０〜Ｇ１３から薄膜の導電弾性物Ｓ１０〜Ｓ１３をそれぞれ作製し、それら導電弾性物Ｓ１０〜Ｓ１３において硬度，引張強度，体積固有抵抗値をそれぞれ測定すると共に、銀粉の脱落の有無，腐食による抵抗値変化をそれぞれ調べ、それら結果を下記表６に示した。なお、下記表６では、導電弾性物Ｓ１０〜Ｓ１３との比較例として、金属粉体の配合量が同じ３００部で導電性が良好な導電弾性物Ｓ２，Ｓ５の結果も示した。
【００４４】
【表６】

【００４５】
前記表６に示すように、形状が薄片状，球状の銀粉を混合して成る金属粉体を用いた導電弾性物Ｓ１３は、導電弾性物Ｓ２，Ｓ５と同様の硬度，引張強度を有し、良好な導電材保持性，耐腐食性が得られたが、十分な導電性が得られなかったことを確認できた。一方、形状が樹枝状，薄片状の銀粉を混合して成る金属粉体を用いた導電弾性物Ｓ１０〜Ｓ１２は、導電弾性物Ｓ２，Ｓ５と同様の硬度，引張強度を有し、良好な導電性が得られると共に十分な導電保持性が得られたことを確認できた。
【００４６】
したがって、単に形状が薄片状または樹枝状の銀粉を用いるのではなく、前記のように形状が樹枝状，薄片状の銀粉を併用したことにより、各銀粉が導電弾性物中にて互いに絡み合い、その導電弾性物において良好な高次構造が構成されることを判明した。
【００４７】
［実施例３；有機珪素化合物による特性変化］
前記実施例１と同様にオルガノポリシロキサン１００部にポリハイドロジェンシロキサンを２．７部，白金触媒を０．１部配合した後、さらに形状が薄片状の銀粉から成る金属粉体または樹枝状，薄片状の銀粉を併用し混合して成る金属粉体を３００部配合すると共に、結合材（金属粉体の脱落を防ぐための結合材）としてグリシジル基，エポキシ基，ビニル基，アルケニル基のうち何れか一つの官能基を有する分子構造の有機珪素化合物を０．５部配合し、混練および架橋することにより下記表７に示すゴムのコンパウンドＧ１４〜Ｇ２１を得た。なお、下記表７では、前記各有機珪素化合物のメーカー等についても示した（オルガノポリシロキサン，銀粉，ポリハイドロジェンポリシロキサン，白金触媒のメーカー等は省略）。
【００４８】
【表７】

【００４９】
そして、実施例１と同様の方法により、前記の各コンパウンドＧ１４〜Ｇ２１から薄膜の導電弾性物Ｓ１４〜Ｓ２１をそれぞれ作製し、それら導電弾性物Ｓ１４〜Ｓ２１において硬度，引張強度，体積固有抵抗値をそれぞれ測定すると共に、銀粉の脱落の有無，腐食による抵抗値変化をそれぞれ調べ、それら結果を下記表８に示した。なお、下記表８では、導電弾性物Ｓ１４〜Ｓ２１との比較例として、５０％平均粒径が１０μｍの球状のメッキ粉体（基材粒子表面に有機珪素化合物の薄膜を被覆してから銀メッキされたメッキ粉体（ユケン工業製））を用いて成る導電弾性物Ｓ２２、および有機珪素化合物が配合されていない導電弾性物Ｓ１０の結果も示した。
【００５０】
【表８】

【００５１】
前記表８に示すように、薄片状の金属粉体，グリシジル基またはエポキシ基を有する有機珪素化合物が配合された導電弾性物Ｓ２０，Ｓ２１は、導電弾性物Ｓ１０と殆ど同様の機械的特性（硬度，引張強度），耐腐食性が得られるが、導電性，導電材保持性が極めて低下してしまったことを確認できた。また、メッキ粉体を用いた導電弾性物Ｓ２２は、導電弾性物Ｓ１０と殆ど同様の機械的特性（硬度，引張強度）が得られるが、導電性，導電材保持性，耐腐食性が極めて低下してしまったことを確認できた。さらに、樹枝状，薄片状の銀粉を併用して成る金属粉体，グリシジル基またはエポキシ基を有する有機珪素化合物が配合された導電弾性物Ｓ１４，Ｓ１５は、導電弾性物Ｓ１０と殆ど同様の機械的特性（硬度，引張強度），導電性，導電材保持性，耐腐食性が得られたことを確認できた。
【００５２】
一方、樹枝状，薄片状の銀粉を併用して成る金属粉体，ビニル基，アルケニル基を有する有機珪素化合物が配合された導電弾性物Ｓ１６〜Ｓ１９は、導電弾性物Ｓ１０と殆ど同様の機械的特性（硬度，引張強度），導電性，耐腐食性が得られると共に、極めて良好な導電材保持性が得られたことを確認できた。
【００５３】
したがって、有機珪素化合物を用いて導電弾性物中の金属粉体の脱落を抑制する場合、導電性材料として樹枝状，薄片状の銀粉を併用した金属粉体を用いることが好ましいことを判明した。また、メッキ粉体のように有機珪素化合物を基材粒子に被覆するのではなく、その有機珪素化合物をシリコーンゴムに対し導電性材料，硬化剤と共に配合し混練させることが好ましいことを判明した。さらに、グリシジル基またはエポキシ基を有する有機珪素化合物よりも、ビニル基，アルケニル基を有する有機珪素化合物を用いることが好ましいことを判明した。
【００５４】
以上、本発明において、記載された具体例に対してのみ詳細に説明したが、本発明の技術思想の範囲で多彩な変形および修正が可能であることは、当業者にとって明白なことであり、このような変形および修正が特許請求の範囲に属することは当然のことである。
【００５５】
例えば、本実施の形態では金属粉体として銀粉を用いたが、その銀粉の替わりにニッケル紛，金紛，銅紛等の導電性の高い金属紛体を適用した場合においても、同様の作用効果が得られることは明らかである。
【００５６】
また、シリコーンゴム，導電性材料，硬化剤，有機珪素化合物を配合するだけでなく、導電弾性物の使用目的に応じて種々の添加剤を配合しても良い。
【００５７】
【発明の効果】
以上示したように本発明によれば、形状が樹枝状，薄片状の金属粉体を用いるため導電弾性物において良好な高次構造を構成でき、高い機械的特性，導電性を確保できると共に導電材保持性，耐腐食性を向上させることが可能となる。
【００５８】
また、金属粉体の脱落を防ぐための添加剤としてビニル基，アルケニル基を有する有機珪素化合物を用いることにより、前記導電材保持性をより向上させることが可能となる。
【００５９】
さらに、シリコーンゴム，金属粉体，硬化剤等を混練して架橋し、その架橋物を有機溶剤でインキ化し被支持体表面に塗布してから再度硬化させることにより所望の形状の導電弾性物を作製するため、極めて薄膜（例えば、０．０１〜０．５ｍｍの薄膜）の導電弾性物を容易に作製できる。
【００６０】
ゆえに、本発明による導電弾性物を例えば電気機器等の電流の接点部分，静電気対策部材，レーザー式プリンタ用の電極，電子機器の電磁波シールド部材，コネクタ類のシール部材等に用いることにより、それら製品の耐久性，電気的特性等を向上させることができると共に、種々の設計変更（例えば、薄膜の導電弾性物による小型化）が容易となる。
【図面の簡単な説明】
【図１】本実施の形態における導電弾性物の製造方法を示す概略説明図。
【図２】本実施の形態における導電材保持性の試験方法を示す概略説明図。
【図３】本実施の形態における耐腐食性の測定方法を示す概略説明図。
【符号の説明】
１１…薄板
１２…耐熱性フィルム
１３…ガラス棒
１４…流延された溶液
２１，３２…試料
２２…線条痕[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a conductive elastic composition and a method for producing the same. For example, the present invention relates to a contact portion for current of an electric device, an antistatic member, an electrode for a laser printer, an electromagnetic wave shielding member of an electronic device, and connectors. It is used for a seal member or the like.
[0002]
[Prior art]
Compositions made of conductive materials (conductive materials such as carbon black and metal powder) and polymer elastic materials (polymer materials such as rubber) (conductive elastic composition; hereinafter, referred to as conductive elastic materials) It is used in various technical fields, for example, a contact point of a current in a keyboard or a remote control of an electric device (for example, a home computer or a television), an antistatic member in an OA floor, a floor material of a factory floor, and an electrification for a laser printer. , Electrodes for developing rollers, etc., electromagnetic wave shielding members for preventing external electric waves of electronic devices, sealing members used for connectors, and the like.
[0003]
Although various polymer elastic materials are used for the conductive elastic material, silicone rubber, which is particularly excellent in processability, is often used. Various materials can also be used as the conductive material. For example, in the case of an electromagnetic wave shielding member, it is necessary to use a low-resistance conductive elastic material, so that nickel powder, copper powder, silver powder, gold powder, solder, and the like are used. Highly conductive metal powders such as are used.
[0004]
As described above, a conductive elastic material made of silicone rubber and metal powder has sufficient conductivity (low volume resistivity), mechanical properties (eg, strength, elasticity), and conductive material retention. (Must not drop metal powder), Corrosion resistance (eg, no change in resistance due to high temperature and high humidity environment), etc. Known are those obtained by adding and mixing large silver to a polymer, and include, for example, conductive elastic materials of an addition reaction curing type, a condensation reaction curing type, and a peroxide vulcanization curing type.
[0005]
For example, in JP-A-2001-172506, JP-A-2002-60625, and JP-A-2002-212426, the average composition formula is represented by R ¹ _n SiO _{(4-n) / 2} , and an aliphatic compound is contained in the molecule. For an organopolysiloxane having at least one unsaturated group (R ¹ in the composition formula is the same or different, unsubstituted or substituted monovalent hydrocarbon group), metal powder (for example, silver powder) or metal powder on the surface A powder having a plating layer (for example, a powder having a silver plating layer formed on the surface of a substrate particle) and a predetermined amount of a curing agent (an amount of a curing agent capable of curing an organopolysiloxane) are added thereto. A conductive elastic material mixed and dispersed by a kneading and dispersing device such as an internal mixer is disclosed.
[0006]
It is described that a powder having a metal plating layer on the surface (hereinafter, referred to as a plating powder) has better dispersibility in silicone rubber and higher conductivity than metal powders such as silver powder. . Further, in order to increase the bonding force between the metal plating layer and the base particles, a thin film of an organosilicon compound having, for example, an epoxy group or a glycidyl group is formed on the surface of the base particles and then coated. Is described. Further, as the above-mentioned metal powder, various shapes such as a flake shape and a grape shape may be used, but a spherical shape is preferable in terms of suppressing aggregation of the respective powders. Has been described.
[0007]
[Patent Document 1]
JP 2001-172506 A (paragraphs [0008] to [0013], [0019]).
[0008]
[Patent Document 2]
JP-A-2002-60625 (paragraphs [0007] to [0011], [0020]).
[0009]
[Patent Document 3]
JP-A-2002-212426 (paragraphs [0007] to [0014]).
[0010]
[Problems to be solved by the invention]
However, in the case of a conductive elastic material in which a plating powder is mixed with silicone rubber as described above, the metal plating layer tends to peel off from the plating powder during the mixing, so that the volume resistivity of the conductive elastic material increases. This causes a problem.
[0011]
Further, when metal powder is used as the conductive material as described above, even if the shape of the metal powder is spherical, the resistance of the conductive elastic material can be reduced as in the case of using the plating powder. In order to achieve this, a large amount of metal powder is required, and as the amount of metal powder used increases, the conductive elastic material becomes excessively hardened and becomes brittle, and its elasticity and conductive material holding properties decrease. I will.
[0012]
Further, when the conductive elastic material as described above is molded into a desired shape, generally, manufacturing methods such as a compression molding method, an extrusion molding method, a calendar molding method, and an inflation processing method are applied. In the manufacturing method, it is difficult to form a thin film (for example, a thin film having a thickness of 0.5 mm or less).
[0013]
The present invention has been made based on the above-mentioned problem, and aims to reduce the resistance of a conductive elastic material (for example, a conductive elastic material of a thin film), suppress the falling off of a conductive material, and improve the mechanical properties and corrosion resistance. An object of the present invention is to provide a conductive elastic material composition that can be favorably prepared and a method for producing the same.
[0014]
[Means for Solving the Problems]
The present invention is intended to solve the above-mentioned problems, and the invention described in claim 1 includes at least a silicone rubber (for example, having an average composition formula represented by R ¹ _n SiO _{(4-n) / 2} and containing Silicone rubber having at least one aliphatic unsaturated group (R ¹ in the composition formula is the same or different unsubstituted or substituted monovalent hydrocarbon group)), conductive material, curing agent (for example, polyhydrogen In the conductive elastic material composition comprising siloxane and platinum catalyst), the conductive material includes a flaky metal powder and a dendritic metal powder.
[0015]
The invention according to claim 2 is characterized in that the metal powder is made of silver (silver powder).
[0016]
The invention according to claim 3 is characterized in that an organosilicon compound having a molecular structure having at least one vinyl group or alkenyl group is blended.
[0017]
According to a fourth aspect of the present invention, in the method for producing a conductive elastic composition, a silicone rubber (for example, having an average compositional formula represented by R ¹ _n SiO _{(4-n) / 2} and having an aliphatic unsaturation in the molecule _). Silicone rubber having at least one group (R ¹ in the composition formula is the same or different, unsubstituted or substituted monovalent hydrocarbon group)), conductive material (for example, metal powder as shown in claims 1 to 3) ), A kneading agent (eg, polyhydrogensiloxane, platinum catalyst) (or kneading silicone rubber, a conductive material, a curing agent, and an organosilicon compound (eg, an organosilicon compound according to claim 3)) Cross-linking, the cross-linked product is made into an ink with an organic solvent, and then applied to the surface of the support (for example, the surface of a heat-resistant film laid on one end side of a thin plate), and then dried and cured (for example, at a higher temperature than drying). Cured with Is allowed to obtain a conductive elastic body composition, said organic solvent is characterized by using a saturated hydrocarbon compound.
[0018]
In general, for example, a compression molding method, an extrusion molding method, or a calendar molding method is applied as a method for producing a conductive elastic material. In each of the above methods, for example, a conductive elastic material of a thin film having a thickness of 0.5 mm or less is applied. It is difficult to manufacture a product (for example, it is difficult to peel a thin film from a calender roll by a calendar molding method). Further, an inflation processing method is applied in a method for producing a resin composition for a thin film. However, in the case of a conductive elastic material, it cannot be applied because the strength before crosslinking is too low.
[0019]
On the other hand, according to the invention as set forth in claim 4, a crosslinked product obtained by blending a silicone rubber, a conductive material, and the like is made into an ink with an organic solvent and then applied to the surface of the support. By adjusting and curing, a thin conductive film (for example, 0.01 to 0.5 mm) can be easily produced.
[0020]
Examples of the organic solvent include aromatic solvents (preferably, toluene, xylene, trimethylbenzene, etc.) and olefin solvents (preferably, petroleum ether, solvent naphtha, mineral spirit, kerosene, sorbets, normal hexane, normal pentane, Isooctane, isoheptane, etc.), ester type (preferably, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl acetate, isobutyl acetate, isobutyl valerate, ethyl lactate, propyl lactate, ethyl formate, butyl formate, formic acid Propyl), ketones (preferably acetone, methyl ethyl ketone, dimethyl ketone, diethyl ketone, etc.), and mixtures of these solvents.
[0021]
Further, a member having heat resistance is used for the support, for example, a polyethylene terephthalate (hereinafter referred to as PET) film, a TPX (polymethylpentenane) film, a polyethylene naphthalate film, a polyetheretherketone film, a polyimide. Film, polyarylate film and the like.
[0022]
Further, when the crosslinked product is formed into an ink with an organic solvent and then applied to the surface of the support, a general roll coater method (for example, a reverse coater method, a doctor blade coater method, a gravure coater method, a comma coater method, etc.), a bar coater method , Screen printing method and the like can be applied. In the screen printing method, for example, a screen plate made of a nylon mesh plate (a screen plate in which the resist thickness is adjusted to, for example, 30 μm by a mesh 100 or 75) is used, and the above-mentioned ink is used as a support. By printing on the surface, a thin conductive elastic material can be obtained.
[0023]
Furthermore, the invention according to claim 4 is not limited to the above-described thinning of the conductive elastic material, but can be applied to the case where the thinning is performed with a composition made of another polymer material. It is possible.
[0024]
In addition, the dendritic metal powder can be obtained by, for example, an electrolyzing method of electrolytically refining crude metal crude steel in an electrolyte solution. The flaky metal powder is prepared by adding a reducing agent to a metal ion solution (a solution in which a metal is dissolved by ionization), or a stamping method (Stamping) in which purified metal powder is flaked by a stamp mill or the like. It can be obtained by a chemical reduction method in which the purified metal is pulverized and flaked. The spherical metal powder can be obtained by, for example, an atomizing method (Atomization) in which unrefined crude metal steel is melted and sprayed in air (or water) to take out a powder.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a conductive elastic composition and a method for producing the same according to an embodiment of the present invention will be described in detail with reference to the drawings and the like.
[0026]
In the present embodiment, a silicone rubber having an average composition formula of R ¹ _n SiO _{(4-n) / 2} and having at least one aliphatic unsaturated group in a molecule (R ¹ in the composition formula is the same or For a different type of unsubstituted or substituted monovalent hydrocarbon group), a predetermined amount of a plurality of metal powders (or plating powders) having different particle shapes and a curing agent is mixed, or the silicone rubber, metal powder, A predetermined amount of an organosilicon compound in addition to the curing agent is blended, kneaded and cured to prepare a sample of a conductive elastic material, and a change in characteristics is examined according to each of the examples described later. Hardness, tensile strength), conductivity, conductive material retention, and corrosion resistance were studied. Further, the present inventors have also studied a manufacturing method capable of making the conductive elastic material thinner.
[0027]
Example 1 Characteristic Change Due to Difference in Shape of Metal Powder
As the silicone rubber, 100 parts of an organopolysiloxane having an average composition formula of R ¹ _n SiO _{(4-n) / 2} and having at least one aliphatic unsaturated group in a molecule is used, and the organopolysiloxane is placed in a container. After mixing 2.7 parts of polyhydrogensiloxane as a curing agent and 0.1 part of a platinum catalyst while stirring with a roll, a silver powder having a dendritic, flaky, or spherical shape was further formed as a metal powder. In the form (1), 200 to 400 parts of silver powder having an average particle diameter of about 1 μm to 50 μm) were mixed, kneaded and crosslinked to obtain rubber compounds G1 to G9 shown in Table 1 below. Table 2 below shows the manufacturers of the organopolysiloxane, silver powder, polyhydrogenpolysiloxane, platinum catalyst, and the like.
[0028]
[Table 1]

[0029]
[Table 2]

[0030]
Then, each of the compounds G1 to G9 is ink-formed (dissolved) with an organic solvent (e.g., an aromatic, olefin-based, ester-based, or ketone-based organic solvent) composed of a saturated hydrocarbon compound. Each of the solutions thus prepared is applied to the surface of a heat-resistant film (for example, a thin film made of PET) 12 laid on one end side of a thin plate 11 as shown in FIG. 1, and a glass rod 13 is used (for example, FIG. 1). In the direction of the arrow).
[0031]
Thereafter, the cast solution (reference numeral 14 in FIG. 1) is dried under predetermined conditions (for example, at a temperature of 40 ° C. for 30 minutes, or at a temperature of 60 ° C. for 20 minutes). By curing at a higher temperature (for example, curing at a temperature of 180 ° C. for 20 minutes or at a temperature of 200 ° C. for 15 minutes), a conductive film of a thin film (thin film having a thickness of 0.1 mm) is formed on the heat-resistant film 12. Elastic objects S1 to S9 were produced respectively.
[0032]
When the heat-resistant film 12 has active hydrogen (active hydrogen in chemical structure), it is necessary to easily separate the conductive elastic substances S1 to S9 from the heat-resistant film 12; For example, after the surface of the heat-resistant film 12 is subjected to release treatment (for example, release treatment using fluorine) in accordance with the degree of activity by hydrogen, the conductive elastic materials S1 to S9 are prepared as shown in FIG. Is also good.
[0033]
When the solution of each of the compounds G1 to G9 applied on the heat resistant film 12 is cast, a spacer (for example, made of PET) having a predetermined thickness is provided between the heat resistant film 12 and the glass rod 13. Although a spacer (not shown) is interposed, a conductive elastic material is prepared by variously changing the thickness of the spacer (that is, the distance between the heat-resistant film 12 and the glass rod 13). Thus, it was confirmed that a very thin conductive elastic material (for example, a thin film having a thickness of about 0.5 to 0.001 mm) was obtained.
[0034]
[Table 3]

[0035]
Next, the hardness (JIS K6253 of JIS), tensile strength (JIS K6252 of JIS), and conductivity (volume resistivity; JIS K7194 of JIS) were measured for the conductive elastic materials S1 to S9. (The conductive material retention test) and the change in resistance value due to corrosion (corrosion resistance test) were examined by the method described below (details will be described later). The results are shown in Table 4 below. In the present embodiment, the target values of the volume resistivity, the conductive material retention, and the corrosion resistance are set to 5.0 × 10 ⁻² Ω · cm or less, and 30 or less dropped silver powder and 1 Ω or less, respectively. Set to.
[0036]
FIG. 2 is a schematic explanatory diagram of the conductive material retention test. First, a cutter knife is rubbed on a partial area (10 mm × 10 mm area) on one end surface side of the sample 21 (conductive elastic substances S1 to S9). By attaching, streaks 22 having a length of 10 mm were formed at intervals of 1 mm, and an adhesive surface of a cellophane tape (registered trademark of NICHIBAN; hereinafter abbreviated) 23 was attached so as to cover the streaks. Then, after rotating a cylindrical roller 24 having a diameter of 30 mm with a load of about 4.9 N (one rotation in one direction) on one end surface of the sample 21, the cellophane tape 23 is peeled off from the sample 21. The number of silver powder (silver powder dropped off by rubbing with a cutter knife) attached to the cellophane tape was examined with a microscope.
[0037]
FIG. 3 is a schematic explanatory view of the corrosion resistance test. First, a tester 31 having two probes 31a and 31b is used, and the probes 31a and 31b are separated from each other by a distance of 3 cm to form a rectangular thin film (0. After measuring the resistance (hereinafter, referred to as resistance before corrosion) by abutting on a sample (8 mm × 50 mm × 50 mm) (conductive elastic materials S1 to S9) 32, the sample 32 was heated to 70 ° C. and 70% relative humidity rh. The resistance (hereinafter, referred to as the post-corrosion resistance) was measured again by using the tester 31 for 500 hours in the atmosphere described above, and the difference between the pre-corrosion resistance and the post-corrosion resistance was calculated.
[0038]
[Table 4]

[0039]
As shown in Table 4, the conductive elastic materials S1 to S9 each had an increased volume resistivity value with an increase in the amount of the silver powder, but if the amount of the silver powder was too large, the hardness became high and the tensile strength was increased. It could be confirmed that it was lowered (for example, conductive elastic materials S3, S6, S9). In addition, the conductive elastic materials S7 to S9 using spherical silver powder have sufficient conductivity when the amount of silver powder is increased, but the conductive material retention is reduced, and when the amount of silver powder is reduced, sufficient conductivity is obtained. It was confirmed that the conductivity was lowered instead of obtaining a good conductive material holding property.
[0040]
On the other hand, the conductive elastic materials S1 to S3 using dendritic silver powder did not have sufficient conductive material retention and corrosion resistance, but had good conductivity (conductivity that achieved the target value). It was confirmed that it was obtained. In addition, the conductive elastic materials S4 to S6 using the flaky silver powder have the same conductivity as the conductive elastic material, and when a sufficient amount of silver powder is used (for example, the conductive elastic material S5). In S6), it was confirmed that good corrosion resistance (corrosion resistance that achieved the target value) was obtained.
[0041]
[Example 2: Change in characteristics due to combination of shapes of metal powder]
As in Example 1, 2.7 parts of polyhydrogensiloxane and 0.1 part of platinum catalyst were added to 100 parts of organopolysiloxane, and then any one of dendritic, flaky, and spherical silver powder was formed. 300 parts of a metal powder obtained by mixing the two at various ratios were mixed, kneaded and crosslinked to obtain rubber compounds G10 to G13 shown in Table 5 below.
[0042]
[Table 5]

[0043]
Then, in the same manner as in Example 1, thin conductive elastic materials S10 to S13 were prepared from the compounds G10 to G13, and the hardness, tensile strength, and volume resistivity of the conductive elastic materials S10 to S13 were measured. In addition to the measurement, the presence or absence of silver powder falling off and the change in resistance value due to corrosion were examined. The results are shown in Table 6 below. In Table 6, below, as a comparative example with the conductive elastic materials S10 to S13, results of the conductive elastic materials S2 and S5 having good conductivity with 300 parts of the same amount of the metal powder are also shown.
[0044]
[Table 6]

[0045]
As shown in Table 6, the conductive elastic material S13 using a metal powder obtained by mixing flaky and spherical silver powder has the same hardness and tensile strength as the conductive elastic materials S2 and S5. It was confirmed that good conductive material retention and corrosion resistance were obtained, but sufficient conductivity was not obtained. On the other hand, the conductive elastic materials S10 to S12 using a metal powder obtained by mixing dendritic and flaky silver powders have the same hardness and tensile strength as the conductive elastic materials S2 and S5, and have good conductivity. It was confirmed that the property was obtained and a sufficient conductivity retention property was obtained.
[0046]
Therefore, instead of simply using flaky or dendritic silver powder in shape, by using dendritic or flaky silver powder in combination as described above, each silver powder is entangled with each other in the conductive elastic material. It has been found that a good higher-order structure is formed in the conductive elastic material.
[0047]
Example 3 Property Change Due to Organic Silicon Compound
In the same manner as in Example 1, 2.7 parts of polyhydrogensiloxane and 0.1 part of platinum catalyst were added to 100 parts of organopolysiloxane, and then a metal powder or a dendritic powder composed of flaky silver powder was further added. 300 parts of a metal powder formed by using and mixing flaky silver powder is used, and glycidyl, epoxy, vinyl, and alkenyl groups are used as a binder (a binder for preventing the metal powder from falling off). 0.5 parts of an organosilicon compound having a molecular structure having any one functional group was mixed, kneaded and crosslinked to obtain rubber compounds G14 to G21 shown in Table 7 below. In Table 7 below, the manufacturers of the respective organosilicon compounds are also shown (the manufacturers of organopolysiloxane, silver powder, polyhydrogenpolysiloxane, platinum catalyst, etc. are omitted).
[0048]
[Table 7]

[0049]
Then, in the same manner as in Example 1, thin conductive elastic materials S14 to S21 were prepared from the compounds G14 to G21, and the hardness, tensile strength, and volume resistivity of the conductive elastic materials S14 to S21 were determined. In addition to the measurement, the presence / absence of silver powder falling off and the change in resistance due to corrosion were examined, and the results are shown in Table 8 below. In Table 8 below, as a comparative example with the conductive elastic substances S14 to S21, a 50% average particle diameter of a spherical plating powder (10 μm average particle diameter) was used. The results are also shown for the conductive elastic material S22 using the plated metal powder (manufactured by Yuken Industries) and the conductive elastic material S10 containing no organosilicon compound.
[0050]
[Table 8]

[0051]
As shown in Table 8, the conductive elastic materials S20 and S21 containing the flaky metal powder and the organosilicon compound having a glycidyl group or an epoxy group had almost the same mechanical properties (hardness) as the conductive elastic material S10. , Tensile strength) and corrosion resistance, but it was confirmed that the conductivity and the retention of the conductive material were extremely reduced. The conductive elastic material S22 using the plating powder has almost the same mechanical properties (hardness and tensile strength) as the conductive elastic material S10, but the conductivity, the retention of the conductive material, and the corrosion resistance are extremely reduced. I was able to confirm that it was done. Further, the conductive elastic materials S14 and S15 containing the metal powder formed by using dendritic or flaky silver powder in combination and the organosilicon compound having a glycidyl group or an epoxy group are almost the same mechanically as the conductive elastic material S10. It was confirmed that properties (hardness, tensile strength), conductivity, conductive material retention, and corrosion resistance were obtained.
[0052]
On the other hand, the conductive elastic materials S16 to S19 containing the metal powder formed by using dendritic or flaky silver powder in combination and the organosilicon compound having a vinyl group or an alkenyl group are almost the same mechanically as the conductive elastic material S10. It was confirmed that properties (hardness, tensile strength), conductivity, and corrosion resistance were obtained, and that extremely good conductive material retention was obtained.
[0053]
Therefore, it has been found that, in the case where the metal powder in the conductive elastic material is prevented from falling off by using the organic silicon compound, it is preferable to use a metal powder which is combined with dendritic or flaky silver powder as the conductive material. It has also been found that it is preferable to mix and knead the organosilicon compound with silicone rubber together with a conductive material and a curing agent, instead of coating the organosilicon compound on the base particles as in the case of plating powder. Further, it has been found that it is preferable to use an organic silicon compound having a vinyl group or an alkenyl group rather than an organic silicon compound having a glycidyl group or an epoxy group.
[0054]
As described above, in the present invention, only the described specific examples have been described in detail, but it is apparent to those skilled in the art that various modifications and variations are possible within the technical idea of the present invention. It is obvious that such changes and modifications belong to the scope of the claims.
[0055]
For example, although silver powder is used as the metal powder in the present embodiment, the same effect can be obtained when a highly conductive metal powder such as nickel powder, gold powder, or copper powder is used instead of the silver powder. It is clear that it can be obtained.
[0056]
In addition to the silicone rubber, the conductive material, the curing agent, and the organic silicon compound, various additives may be blended according to the intended use of the conductive elastic material.
[0057]
【The invention's effect】
As described above, according to the present invention, since a dendritic or flaky metal powder is used, a favorable higher-order structure can be formed in a conductive elastic material, high mechanical properties and conductivity can be ensured, and the conductive property can be improved. Material retention and corrosion resistance can be improved.
[0058]
Further, by using an organic silicon compound having a vinyl group or an alkenyl group as an additive for preventing the metal powder from falling off, it is possible to further improve the conductive material retention.
[0059]
Furthermore, silicone rubber, metal powder, a curing agent, and the like are kneaded and crosslinked, and the crosslinked product is made into an ink with an organic solvent, applied to the surface of the support, and then cured again to obtain a conductive elastic material having a desired shape. Since it is manufactured, an extremely thin conductive elastic material (for example, a thin film having a thickness of 0.01 to 0.5 mm) can be easily manufactured.
[0060]
Therefore, by using the conductive elastic material according to the present invention for a current contact portion of an electric device, an antistatic member, an electrode for a laser printer, an electromagnetic wave shielding member of an electronic device, a sealing member of a connector, etc. In addition to improving the durability and electrical characteristics of the thin film, various design changes (for example, miniaturization of the thin film by using a conductive elastic material) are facilitated.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a method for manufacturing a conductive elastic material according to the present embodiment.
FIG. 2 is a schematic explanatory view showing a test method of a conductive material holding property in the present embodiment.
FIG. 3 is a schematic explanatory view showing a method for measuring corrosion resistance in the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Thin plate 12 ... Heat resistant film 13 ... Glass rod 14 ...

Cast solution

21, 32 ... Sample 22 ... Streak marks

Claims

In a conductive elastic composition comprising at least silicone rubber, a conductive material, and a curing agent,
The conductive elastic material composition, wherein the conductive material includes a flaky metal powder and a dendritic metal powder.

The conductive elastic body composition according to claim 1, wherein the metal powder is made of silver.

3. The conductive elastic composition according to claim 1, further comprising an organosilicon compound having a molecular structure having at least one vinyl group or alkenyl group.

A silicone rubber, a conductive material, and a curing agent are kneaded to form a crosslink, and the crosslinked product is formed into an ink with an organic solvent, and then applied to the surface of the support, then dried and cured to obtain a conductive elastic composition.
A method for producing a conductive elastic composition, wherein a saturated hydrocarbon compound is used as the organic solvent.