JP3576413B2 - Method for producing microcapsule type curing catalyst - Google Patents

Description

（Ｒ１ 、Ｒ２ 及びＲ３ は、それぞれ独立に水素原子、アルキル基、アルケニル基、シクロアルキル基、アリール基、またはこれらの基以外でケイ素に直結する基が炭素である基、アルキルシリル基、アルキルアミノ基、アルコキシ基を表わす。ただし、Ｒ１ 、Ｒ２ 及びＲ３ の少なくとも１つは水素原子である。）
本発明では、Ｒ１ 、Ｒ２ 及びＲ３ のすべてが水素原子であるペルヒドロポリシラザンが特に好ましく、例えば、東燃（株）社製、Ｎ１１０，Ｌ１１０，ＮＶ１１０などが挙げられる。
【００１４】
ここで、本発明においてコア材料として用いられる硬化触媒について、一般的には以下のようなものが例示される。例えば、過酸化ベンゾイル、過硫化カリウム、ｔ−ブチルヒドロキシペルオキシド、クメンヒドロペルオキシド、アゾビスイソブチロニトリル、アゾビスシクロヘキサンカルボニトリルなどのラジカル触媒；三フッ化ホウ素ジエチルエーテラート、三フッ化ホウ素アミン錯体、塩化アルミニウム、塩化第二スズ、四塩化チタン、アルキルアルミニウムなどのカチオン触媒；ｎ−ブチルリチウム、ナフタリンナトリウム、アミン類などのアニオン触媒；水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム、炭酸カリウム、ヨウ化カリウム、カルボン酸類、スルホン酸類、アルデヒド類、水などその他の触媒などである。
【００１５】
また、特にエポキシ樹脂用として好適な硬化触媒としては具体的には以下のようなものが例示される。例えば、２−メチルイミダゾール、２，４−ジメチルイミダゾール、２−エチル−４−メチルイミダゾール、２−フェニルイミダゾール、２−フェニル−４−メチルイミダゾール、２−ヘプタデシルイミダゾールなどのイミダゾール化合物およびその誘導体；トリフェニルホスフィン、トリメチルホスフィン、トリエチルホスフィン、トリブチルホスフィン、トリ（ｐ−メチルフェニル）ホスフィン、トリ（ノニルフェニル）ホスフィン、メチルジフェニルホスフィン、ジブチルフェニルホスフィン、トリシクロヘキシルホスフィン、１，２−ビス（ジフェニルホスフィノ）エタン、ビス（ジフェニルホスフィノ）メタンなどの有機ホスフィン化合物；ＤＢＡ−ＤＢＵ（６−ジブチルアミノ−１，８−ジアザビシクロ（５，４，０）ウンデセン−７）、ＤＢＵ（１，８−ジアザビシクロ（５，４，０）ウンデセン）、ＤＢＮ（１，５−ジアザビシクロ〔４，３，０〕５−ノネン）などのＤＢＵ系化合物；テトラメチルグアニジン、トリエタノールアミン、２−ジメチルアミノ−２−ヒドロキシプロパン、ジアルキルアミノエタノール、Ｎ，Ｎ’−ジメチルピペラジン、Ｎ−メチルモルホリン、ヘキサメチレンテトラミン、１−ヒドロキシエチル−２−ヘプタデシルグリオキサリジン、ピリジン、ピラジン、キノリン、ベンジルジメチルアミン、α−メチルベンジルジメチルアミン、２−（ジメチルアミノメチル）フェノール、２，４，６−トリス（ジメチルアミノメチル）フェノールなどの第三アミン化合物などである。
【００１６】
これらの硬化触媒は、単独でまたは必要に応じて２種以上混合して使用される。またこれらの硬化触媒は、フェノールなどとの錯塩や、単官能または多官能のエポキシ樹脂との付加物として用いることもできる。このような錯塩や付加物を用いれば、コア材料の融点を最適化でき、ひいてはカプセルからコア材料である硬化触媒を放出させる温度を最適に設定することもできる。さらに、これらの硬化触媒は、化学的に安定な無機材料の固体マトリクスまたは多孔質体に混合または含浸させた後、粉砕するか液相で撹拌し粒子化して用いることもできる。
【００１７】
ポリシラザンは、低温でアミン類及び水蒸気と接触させ、その後に乾燥雰囲気中で乾燥させることで容易にセラミック化する。該処理に当たっては、ポリシラザンを有機溶媒に溶解し溶液を調製する。
【００１８】
この場合の有機溶媒としては、特に限定されるものではないが、好ましい具体例としては、ベンゼン、トルエン、キシレン、エチルベンゼン、トリメチルベンゼン等の芳香族系溶媒；ｎ−ペンタン、ｉ−ペンタン、ｎ−ヘキサン、ｉ−ヘキサン、ｎ−ヘプタン、ｉ−ヘプタン、ｎ−オクタン、ｉ−オクタン等の飽和炭化水素化合物系溶媒；ジプロピルエーテル、ジブチルエーテル等のエーテル類；エチルシクロヘキサン、メチルシクロヘキサン、シクロヘキサン、シクロヘキセン、ｐ−メンタン、デカヒドロナフタレン、ジペンテン； ＭＩＢＫ等のケトン類などが挙げられる。
【００１９】
例えば、コア材料にトリフェニルホスフィン（ＴＰＰ）を用いる場合、ベンゼンやキシレンと言った芳香族系溶媒では、粒径制御の点から化学的手法によりカプセル化し、一方、ｎ−ヘキサンやジブチルエーテルのような溶媒に対しては、機械的手法を用いても容易にカプセル化できる。
【００２０】
前記コア剤を含有したポリシラザンを低温でアミン類及び水蒸気と接触させセラミック化を行うが、ここで用いられるアミン類の具体例としては、メチルアミン、ジメチルアミン、トリメチルアミン、エチルアミン、ジエチルアミン、トリエチルアミン、プロピルアミン、ジプロピルアミン、トリプロピルアミン、ブチルアミン、ジブチルアミン、トリブチルアミン、ペンチルアミン、ジペンチルアミン、トリペンチルアミン、ヘキシルアミン、ジヘキシルアミン、トリヘキシルアミン、ヘプチルアミン、ジヘプチルアミン、オクチルアミン、ジオクチルアミン、トリオクチルアミン、フェニルアミン、ジフェニルアミン、トリフェニルアミン等（なお、炭化水素鎖は直鎖でも分枝鎖でもよい。）、また、ピリジン類としては、例えば、ピリジン、α−ピコリン、β−ピコリン、γ−ピコリン、ピペリジン、ルチジン、ピリミジン、ピリダジン等が挙げられ、更に、ＤＢＵ、ＤＢＮなどが挙げられる。
【００２１】
ポリシラザンとアミン類及び水蒸気との接触方法には、コア剤表面に塗布したポリシラザンを噴霧し、アミン類の蒸気と水蒸気の混合ガス雰囲気中にさらす（主に機械的手法を用いる場合）、アミン類の水溶液に浸漬する（主に化学的手法に用いる場合）、という二つの方法がある。
【００２２】
前者の手法を用いた場合、ポリシラザンとアミン類の蒸気及び水蒸気との接触温度は、用いるポリシラザンのグレードにより異なるが、１００℃以下の低温でシリカに転化するタイプが好ましい。後者の方法においては、コア剤として第三アミン類を用いる場合を除き、アミン類の水溶液中のアミン類濃度は０．０１〜８０重量％、好ましくは０．１〜１０重量％であり、アミン類の水溶液の温度は０℃〜１００℃、好ましくは１０℃〜８０℃の処理でシリカに転化するタイプのポリシラザンを用いるのが好ましい。
【００２３】
本発明において、 ＳｉＯ_２に転化した層からなるシェルの膜厚は、用途に応じて適宜設定されるが、５ｎｍ〜２００μｍ、さらには１０ｎｍ〜１０μｍの範囲であることが好ましい。これは、シェルの膜厚が２００μｍを超えるとシェルが強固になるためカプセルの破壊によりコア材料である硬化触媒を放出させることが困難になり、逆に５ｎｍ未満では十分なカプセル化効果が得られなくなるためである。
【００２４】
本発明において、コア材料である硬化触媒の粒子の粒径は用途に応じて適宜設定されるが、一般的には０．１μｍ以上３０μｍ未満の範囲である。これは、３０μｍ以上の場合には触媒反応が不均一に起こり硬化樹脂の特性にばらつきが生じるおそれがあり、逆に０．１μｍ未満の場合にはカプセル化処理自体を均一に行うことができずカプセル化効果が得られないおそれがあるためである。
【００２５】
本発明のマイクロカプセル型硬化触媒について、シェルを破壊してコア材料である硬化触媒を放出させる方法は特に限定されない。例えば、高速回転・高せん断力の撹拌を行うかまたは直接圧縮して外部から圧力を加えてシェルを破壊してもよい。また、温度上昇によりコア材料を融解または熱膨張させて内圧の増加によりシェルを破壊してもよい。このような方法により潜在性を発揮させることができる。
【００２６】
次いで、樹脂組成物について説明する。樹脂組成物は、硬化性樹脂と、硬化触媒を含有するコアをポリシラザン由来のＳｉＯ₂から構成される無機材料からなるシェルで被覆したマイクロカプセル型硬化触媒とを含有するものが挙げられる。より具体的には、例えばエポキシ樹脂と、エポキシ樹脂の硬化剤と、エポキシ樹脂の硬化触媒を含有するコアをポリシラザン由来のＳｉＯ₂から構成される無機材料からなるシェルで被覆したマイクロカプセル型硬化触媒とを含有する樹脂組成物が挙げられる。
【００２７】
エポキシ樹脂の他に、含んでも良い硬化性樹脂は特に限定されず、以下のようなものが例示される。例えば、ラジカル重合するものとしてスチレン、メタクリル酸メチル、アクリル酸メチル、酢酸ビニル、アクリロニトリル、ビニルピロリドン、無水マレイン酸、エチレン、プロピレン、イソブテン、ブタジエン、イソプレン、１−オクテンなど；カチオン重合するものとしてスチレン、α−メチルスチレン、ｐ−クロロスチレン、３−メチルブテン−１、４−メチルペンテン−１、β−ピネン、イソブテン、イソブチルビニルエーテル、Ｎ−ビニルカルバゾール、ビニルトリメチルシリルエーテル、Ｎ−ビニルカルバゾール、ビニルトリメチルシリルエーテル、エチレンオキシド、フェニルグリシジルエーテル、３，３−ビス（クロロメチル）オキセタン、テトラヒドロフラン、トリオキサン、β−プロピオラクトン、ε−カプロラクタム、オクタメチルシクロテトラシロキサン、フェニルジアゾメタン、ノボラックなど；アニオン重合するものとしてスチレン、α−メチルスチレン、メタクリル酸メチル、アクリルアミド、クロトンアミド、Ｎ−カルボキシアミノ酸無水物、ノボラックなど；その他のものとしてシアノアクリル酸メチル、尿素ホルムアルデヒド、メラミンホルムアルデヒド、ナイロン、ウレタンなどが挙げられる。これらは、単独で用いて単独重合体としてもよいし、２種以上混合して共重合体としてもよい。
【００２８】
また、特にエポキシ樹脂としては具体的には、ビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂、ビスフェノールＳ型エポキシ樹脂、脂環式エポキシ樹脂、複素環式エポキシ樹脂、フェノールまたはクレゾールノボラック型エポキシ樹脂、トリまたはテトラ（ヒドロキシフェニル）アルカンから誘導されるエポキシ化合物、ビスヒドロキシビフェニル系エポキシ樹脂などが挙げられる。これらのエポキシ樹脂は液状でも固体状でもよく、そのエポキシ当量も特に限定されず、単独でまたは２種以上混合して用いることができる。
【００２９】
エポキシ樹脂に対して用いられる硬化剤としては、具体的には以下のようなものが例示される。例えば、ポリメチレンジアミン、ポリエーテルジアミン、ジエチレントリアミン、イミノビスプロピルアミン、ビス（ヘキサメチレン）トリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンペンタミン、ジメチルアミノプロピルアミン、ジエチルアミノプロピルアミン、アミノエチルエタノールアミン、メチルイミノビスプロピルアミン、メンセンジアミン、Ｎ−アミノエチルピペラジン、１，３−ジアミノシクロヘキサン、イソホロンジアミン、ｍ−キシリレンジアミン、テトラクロロ−ｐ−キシリレンジアミンなどの脂肪族ポリアミン化合物；ｍ−フェニレンジアミン、ジアミノジフェニルエーテル、ジアミノジフェニルスルホン、４，４’−メチレンジアニリン、ベンジジン、４，４’−チオジアニリン、４，４’−（ｏ−トルイジン）、ｏ−フェニレンジアミン、ジアニシジン、メチレンビス（ｏ−クロロアニリン）、ビス（３，４−ジアミノジフェニル）スルホン、２，４−トルエンジアミン、ジアミノジトリルスルホン、２，６−ジアミノピリジン、４−クロロ−ｏ−フェニレンジアミン、４−メトキシ−６−メチル−ｍ−フェニレンジアミン、ｍ−アミノベンジルアミンなどの芳香族アミン化合物；Ｎ−メチルピペラジン、ピペリジン、ヒドロキシエチルピペラジン、ピロリジン、モルホリンなどの第二アミン化合物；無水フタル酸、無水イタコン酸、無水コハク酸、無水シトラコン酸、無水アルケニル酸、無水ドデセニルコハク酸、無水トリカルバリル酸、無水マレイン酸、無水マレイン酸のリノレイン酸付加物、無水マレイン酸−ビニルエーテル共重合体、無水マレイン酸−スチレン共重合体、メチルシクロペンタジエンの無水マレイン酸付加物、無水クロレンディック酸、無水アルキル化エンドアルキレンテトラヒドロフタル酸、無水メチル２置換ブテニルテトラヒドロフタル酸、無水ヘキサヒドロフタル酸、無水メチルテトラヒドロフタル酸、無水ピロメリット酸、無水シクロペンタンテトラカルボン酸、無水ベンゾフェノンテトラカルボン酸、エチレングリコールビストリメリテイト、グリセリントリストリメリテイトなどのカルボン酸無水物；フェノールノボラック、クレゾールノボラック、ノニルフェノールノボラック、ビスフェノールＦ型ノボラック、ビスフェノールＡ型ノボラック、ナフトール型ノボラック、ビフェニル構造含有ノボラック、ポリビニルフェノール、ポリパラオキシスチレン、２，２´−ジメトキシーｐ−キシレンとフェノールモノマーとの縮重合化合物などのフェノールアラルキル、ジシクロペンタジエン・フェノール重合体などのフェノール樹脂；その他ポリアミド樹脂、ポリスルフィド樹脂などが挙げられる。
【００３０】
樹脂組成物における各成分の配合量については、各成分の種類、組み合わせに応じて適宜設定すればよい。一般的には硬化性樹脂１００重量部に対し、硬化触媒が０．１〜５０重量部、硬化剤が１０〜２００重量部程度配合される。すなわち、硬化触媒の配合量が少なすぎると硬化が十分に行なわれなくなるおそれがあり、硬化触媒の配合量が多すぎると、硬化時における作業性や混合の均一性、さらには硬化物における電気的特性の低下などを招きやすい。一方、硬化剤の配合量が少なすぎると機械的強度、電気的特性の良好な硬化物が得られ難く、硬化剤の配合量が多すぎると硬化不十分でかえって機械的強度、電気的特性が損なわれる傾向がある。
【００３１】
さらに、特にエポキシ樹脂に対する有機ホスフィン化合物、イミダゾール化合物、ＤＢＵ系化合物などアニオン系の硬化触媒が配合される場合、そのより好ましい配合量は０．１〜１０重量部である。ただし、上述したような硬化触媒をエポキシ樹脂との付加物として用いる場合は、硬化触媒を樹脂組成物の硬化物中に取り込ませることができるので、１０〜５０重量部の配合量でも好ましく使用され得る。また、エポキシ樹脂に対する硬化剤の配合量は、硬化剤におけるエポキシ基と反応する官能基の数を考慮して設定されることがより好ましい。具体的には、全エポキシ基数に対する硬化剤の全官能基数の比が０．６〜１．４となる範囲であり、全エポキシ数と全官能基数とがほぼ当量となる配合量が最も好ましい。
【００３２】
樹脂組成物には、硬化物の特性を向上させるために、適当な充填剤を混合してもよい。充填剤としては、具体的には溶融シリカ、結晶シリカ、アルミナ、マグネシア、窒化ケイ素、窒化アルミニウム、窒化ホウ素などの粉末、短繊維、または長繊維からなる無機系充填剤；熱可塑性樹脂などの有機系充填剤が挙げられる。これらの充填剤は、単独でまたは２種以上混合して用いることができる。
【００３３】
樹脂組成物には、本発明の効果を失わない範囲内で、必要に応じてさらに希釈剤、可とう性付与剤、離型剤、カップリング剤などの添加剤を添加してもよい。
（実施例）以下、本発明の実施例を説明する。まず、本発明に係るマイクロカプセル型硬化触媒（ＭＡ１）〜（ＭＡ４）を以下のようにして調製した。なお、試薬は市販品を用い、反応は不活性ガス雰囲気下で行った。作製したマイクロカプセル型硬化触媒は１〜３０μｍの粒径に分球したものを組成物に用いた。また、ここでの調製例中、各成分の配合比は全て重量比で換算したものである。
【００３４】
（ＭＡ１）コア材料としての粉砕機により平均粒径１０μｍに粉砕した２−フェニルイミダゾール２０部を、シェル原料としてのペルヒドロポリシラザンのｍ−キシレン２０％溶液１００部に混合して分散させ、疎水性混合物を作製した。ポリオキシエチレンノニルフェニルエーテル０．１部を添加した水２００部中に上記疎水性混合物を加え、撹拌して分散させた。この分散液にトリエチルアミン１０部を加え、さらに２４時間攪拌した。反応終了後、数回水洗し、ガラスフィルターまたは遠心分離器を用いて分離し、減圧下で乾燥することによりマイクロカプセル型硬化触媒を得た。シェルの厚さは平均５００ｎｍであった。
【００３５】
（ＭＡ２）コア材料としての粉砕機により平均粒径１０μｍに粉砕したトリフェニルホスフィン３０部を、シェル原料としてのペルヒドロポリシラザンのジブチルエーテル２０％溶液１００部に混合して分散させ、疎水性混合物を作製した。ポリオキシエチレンノニルフェニルエーテル０．１部を添加した水２００部中に上記疎水性混合物を加え、撹拌して分散させた。この分散液にトリエチルアミン１０部を加え、さらに２４時間攪拌した。反応終了後、数回水洗し、ガラスフィルターまたは遠心分離器を用いて分離し、減圧下で乾燥することによりマイクロカプセル型硬化触媒を得た。シェルの厚さは平均６００ｎｍであった。
【００３６】
（ＭＡ３）コア材料としてＤＢＡ−ＤＢＵ３０部をペルヒドロポリシラザンのシクロヘキサン２０％溶液１００部に混合後、３０分間攪拌し疎水性混合物を作製した。この混合物をポリオキシエチレンノニルフェニルエーテル０．１部を添加した水２００部中に滴下し、２４時間攪拌して分散させた。反応終了後、数回水洗し、ガラスフィルターまたは遠心分離器を用いて分離し、減圧下で乾燥することによりマイクロカプセル型硬化触媒を得た。シェルの厚さは平均８００ｎｍであった。
【００３７】
（ＭＡ４）コア材料としての粉砕機により平均粒径１０μｍに粉砕したトリフェニルホスフィン３０部を、シェル原料としてのペルヒドロポリシラザンのシクロヘキサン２０％溶液１００部に混合して分散させた懸濁液を作製した。この懸濁液をスプレードライ造粒装置の供給部に備え、トリエチルアミン１０％含有水溶液の蒸気を満たし、８０℃に設定した室内に噴霧し造粒した。作成した粒子をｍ−キシレンで洗浄し乾燥することによりマイクロカプセル型硬化触媒を得た。シェルの厚さは平均８００ｎｍであった。
【００３８】
また、比較のために、以下のようにして従来の硬化促進剤（Ａ１）〜（Ａ３）を調製した。
【００３９】
（Ａ１）平均粒径１０μｍとなるよう粉砕したトリフェニルホスフィンをそのまま硬化触媒に用いた。
【００４０】
（Ａ２）コア材料としての粉砕機により平均粒径１０μｍに粉砕したトリフェニルホスフィン６０部を四級アンモニウム系界面活性剤０．５部とともにヘキサン１００部に分散させた。この分散液にシェル原料としてのトリレンジイソシアネート０．２部を溶解し、３０分間撹拌した。反応終了後、ヘキサンで数回洗浄し、ガラスフィルターまたは遠心分離器を用いて分離し、減圧下で乾燥することによりマイクロカプセル型硬化促進剤を得た。シェルの厚さは平均５０ｎｍであった。
【００４１】
（Ａ３）粉砕機により平均粒径１０μｍに粉砕した２−フェニルイミダゾールをそのまま硬化触媒として用いた。
【００４２】
（Ａ４）ＤＢＡ−ＤＢＵをそのまま用いた。
次いで、液状ビスフェノールＦ型エポキシ樹脂と無水メチルテトラヒドロフタル酸の同量混合物に上記で調製した硬化触媒（ＭＡ１）〜（ＭＡ４）および（Ａ１）〜（Ａ４）を２部混合したサンプルのＤＳＣ測定を行い、硬化発熱によるピーク開始温度を調べた。
【表１】

【表２】

さらに、表２に示す配合割合で樹脂、硬化剤および充填剤とともに混合し、実施例（１）〜（６）および比較例（１）〜（４）の樹脂組成物を調製した。調製方法として、実施例（１）〜（４）および比較例（１）〜（３）はヘンシェルミキサーにより均一混合後、約１００℃に設定した熱ロールで３分間混合した。また実施例（５），（６）および比較例（４）は、ミキサーにて混合後、３本ロールに３回通して調製した。
【００４３】
得られた各樹脂組成物について、調製直後および４０℃で１か月保存した後にそれぞれ粘度を測定することにより、保存安定性を評価した。評価基準は以下の通りである。すなわち、保存後の粘度を調製直後の値と比較して、変化がない場合を「優」、２倍以下の場合を「良」、２倍以上の変化を示した場合を「不可」とした。
【００４４】
また、各樹脂組成物のうち▲１▼実施例（１）〜（４）および比較例（１）〜（３）は１７５℃、３分、さらにアフターキュアとして１８０℃、８時間の条件で、▲２▼実施例（５），（６）および比較例（４）の組成物は１５０℃、４時間の条件で硬化させ、硬化物の曲げ強度を測定した。硬化性については、▲１▼の場合、１７５℃、３分硬化の型開き直後の成形品のバーコール硬度を、▲２▼の場合、金属板上に組成物をポッティングし、所定温度で硬化直後のバーコール硬度で判断した。これらの結果を表３に記する。
【表３】

なお、表２における樹脂、硬化剤および充填剤の記号は以下の材料を表す。
樹脂
（エポキシ樹脂Ａ）クレゾールノボラック型エポキシ樹脂
（エポキシ樹脂Ｂ）液状ビスフェノールＦ型エポキシ樹脂
硬化剤
（硬化剤Ａ）クレゾールノボラック樹脂
（硬化剤Ｂ）無水メチルテトラヒドロフタル酸
充填剤
（Ｆ１）溶融シリカ粉末、平均粒径２０μｍ
（Ｆ２）溶融シリカ粉末、平均粒径５μｍ
顔料
カーボンブラック
表面処理剤
γ−グリシジルプロビルトリメトキシシラン
離型剤
カルナバワックス
表１に示されている通り、触媒をマイクロカプセル化することによって硬化開始温度が高くなり、潜在性を示すことが判る。さらに表２に示される通り、比較例（２）の樹脂組成物は、ＤＳＣ測定の結果から潜在性硬化性を示すが、長期の保存安定性は無くなっているのに対し、試料（１）〜（６）の樹脂組成物においては、いずれも長期保存後の粘度の変化が小さく保存安定性が優れている。さらに、シェル材料が樹脂組成物の硬化後も無機充填剤として残存するので、半導体封止用途に用いる場合、不純物として作用しないといえる。
【００４５】
【発明の効果】
以上詳述したように本発明によれば、硬化触媒を含有するコアをポリシラザン由来のＳｉＯ２から構成される無機材料からなるシェルで被覆したマイクロカプセル型硬化触媒を提供でき、シェルの耐薬品性、耐水性、耐熱性を生かし、使用される硬化剤などの種類にかかわらず高い保存安定性を実現できる。また、このようなマイクロカプセル型硬化触媒を含有し、安定した硬化開始温度を示す樹脂組成物を提供できる。さらに、硬化後に残留するシェルは無機材料であることから不純物を溶出することがなく、しかも無機充填剤と同様に作用するため、硬化物としての信頼性を向上することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microcapsule-type curing catalyst and a resin composition for encapsulating a semiconductor using the same.
[0002]
[Prior art]
Semiconductor devices such as ICs and LSIs are generally encapsulated using an epoxy resin composition to form a semiconductor device.These devices are formed by sealing a liquid epoxy resin composition at room temperature by potting, capillary force, or the like. The composition is properly used depending on the type of device, such as sealing a composition in a solid state at room temperature by transfer molding. This type of epoxy resin composition usually contains, in addition to the epoxy resin, various curing agents, inorganic fillers, and a curing catalyst.
[0003]
However, the epoxy resin composition must be stored at a low temperature from the viewpoint of storage stability, and when returning to normal temperature during use, attention must be paid to the moisture absorption of the resin composition, which makes the resin management difficult. are doing. Of these, the liquid type composition is generally used as a so-called two-pack type in which the main components, an epoxy resin and a curing agent / curing catalyst, are separately stored and mixed as needed upon use. However, such a two-pack type epoxy resin requires weighing / mixing work immediately before use, and often requires a long working time. This makes it difficult to control the uniformity of mixing, deterioration due to the progress of curing during operation, and voiding of products. Further, it is not preferable not only to simplify the process but also to control the quality, in order to repeat the operation of measuring and mixing the two liquids according to the pot life.
[0004]
In order to ensure the storage stability at room temperature of the epoxy resin having the above problems, the curing catalyst is inactive at room temperature but becomes active rapidly when heated. That is, it is necessary to have potential. In order to develop catalytic activity thermally, ion dissociation reaction and dissolution of the curing catalyst itself, elution of the curing catalyst impregnated in a porous carrier, destruction of microcapsules in which the surface of the curing catalyst particles are coated with an inert substance, etc. Is considered. Of these methods, when using the chemical reactivity of the curing catalyst itself to make it latent, the temperature at which the curing catalyst becomes active is not clear, and it is difficult to achieve sufficient storage stability and rapid curability. It is. Further, in this method, the potential of the curing catalyst greatly changes depending on the type of the curing agent or the like added, and sometimes the potential is completely lost. On the other hand, microencapsulation of the curing catalyst is considered to be effective in solving these problems.
[0005]
In the microcapsule type curing catalyst proposed so far, a thermoplastic resin (Japanese Patent Application Laid-Open No. 2-292325), a thermosetting resin (Japanese Patent Application Laid-Open No. 1-287131), or an epoxy-amine adduct (Japanese Patent Application Laid-Open No. It has been studied to use, for example, No. 2-11619). If these materials are coated with the curing catalyst, which is the core material, storage stability will be improved, but since these materials are organic polymers or oligomers, there is limited choice in relation to the materials contained in the system. . That is, the organic shell material may lose the encapsulation effect due to swelling, penetration, dissolution, and the like. For this reason, a microcapsule-type curing catalyst using an organic shell material can be used together with, for example, an amine-based curing agent among curing agents for an epoxy resin, but when used together with an acid anhydride-based curing agent, its potential is reduced. In some cases, it was damaged. Further, in the case of a microcapsule-type curing catalyst using a shell material such as an epoxy-amine adduct, the reaction proceeds gradually, and there is a problem that the curing start temperature is deviated and, in some cases, the curing is not performed. As described above, in many cases, sufficient chemical resistance, heat resistance, storage stability, and the like cannot be obtained with an organic shell. In particular, there are many restrictions when a core material is a chemically active curing catalyst and a microcapsule-type curing catalyst in which the core material is encapsulated is used in an organic matrix.
[0006]
Therefore, use of a raw material that can be expected to form a stronger shell has been studied. For example, a method has been proposed in which an organosiloxane having an unsaturated hydrocarbon group introduced therein is used as a shell material, and the capsule is encapsulated and then cured by a crosslinking reaction (JP-A-5-271546). However, even in this method, since a carbon-carbon bond is generated by a crosslinking reaction, its chemical resistance, heat resistance, storage stability, and the like are not sufficient.
[0007]
Therefore, in order to solve such a problem, the present inventors have previously devised a microcapsule-type curing catalyst that forms a shell made of an inorganic material, and use physicochemical and mechanical methods using solid powder. We proposed various preparation methods such as encapsulation, encapsulation using glass formation from a glass precursor polymer, and encapsulation using a sol-gel method, and obtained a microcapsule-type curing catalyst with excellent storage stability. However, the production process must be accompanied by a treatment at a high temperature, which is not sufficient considering the catalytic activity after microencapsulation.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a microcapsule-type curing catalyst having excellent storage stability and the like. Another object of the present invention is to provide a resin composition for semiconductor encapsulation which contains the above-mentioned microcapsule-type curing catalyst, is excellent in storage stability, and can obtain a cured product excellent in moldability and reliability. It is in.
[0009]
[Means for Solving the Problems]
In the method for producing a microcapsule-type curing catalyst of the present invention, a step of allowing polysilazane to exist on the surface of the curing catalyst, and contacting the polysilazane on the surface of the curing catalyst with amines and water vapor at 100 ° C. or lower, _Two The curing catalyst is converted to SiO 2 _Two And encapsulating it with a cap.
Obtained by the production method of the present inventionThe microcapsule-type curing catalyst has a core containing the curing catalyst formed of polysilazane-derived SiO2._TwoIt is characterized by being coated with a shell composed of components. As a curing catalyst, an imidazole compound, an organic phosphine compound, or a DBU compoundIs mentioned.
[0010]
Also,Using the microcapsule curing catalyst obtained by the production method of the present inventionThe resin composition comprises a curable catalyst and a core containing the curing catalyst formed of a polysilazane-derived SiO2._TwoAnd a microcapsule-type curing catalyst coated with a shell composed of componentsThings.As a more specific resin composition, a core containing an epoxy resin, a curing agent for the epoxy resin, and a curing catalyst for the epoxy resin is formed of a polysilazane-derived SiO2._TwoAnd a microcapsule-type curing catalyst coated with a shell composed of components. In these resin compositions, the particle size of the curing catalyst constituting the microcapsule-type curing catalyst is preferably 0.1 μm or more and less than 30 μm.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
In the microcapsule-type curing catalyst of the present invention, the core containing the curing catalyst is formed of polysilazane-derived SiO2.₂These shells are coated with a polysilazane as a starting material, and are particularly treated by a low-temperature ceramicization method at a temperature of 100 ° C. or less, thereby impairing the curing catalyst used for the core. At low temperatures such as not₂A film is formed, and a microcapsule-type curing catalyst suitable for the present invention is provided. If any polysilazane can be used as long as it can be ceramicized at a low temperature, SiO 2 can be used.₂A film can be formed.
[0012]
The polysilazane that can be used in the present invention is obtained by modifying a polysilazane having a main skeleton composed of a unit represented by the following chemical formula 1 and having a number average molecular weight of 100 to 50,000.
Embedded image

(R 1, R 2 and R 3 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or a group other than these groups in which a group directly bonded to silicon is carbon, an alkylsilyl group, an alkylamino Or an alkoxy group, provided that at least one of R1, R2 and R3 is a hydrogen atom.)
In the present invention, perhydropolysilazane in which all of R1, R2 and R3 are hydrogen atoms is particularly preferred, and examples thereof include N110, L110 and NV110 manufactured by Tonen Corp.
[0014]
Here, the following are generally exemplified as the curing catalyst used as the core material in the present invention. For example, radical catalysts such as benzoyl peroxide, potassium persulfide, t-butylhydroxy peroxide, cumene hydroperoxide, azobisisobutyronitrile, azobiscyclohexanecarbonitrile; boron trifluoride diethyl etherate, boron trifluoride amine Cationic catalysts such as complexes, aluminum chloride, stannic chloride, titanium tetrachloride, and alkylaluminum; anionic catalysts such as n-butyllithium, sodium naphthalene, and amines; sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate; Other catalysts such as potassium iodide, carboxylic acids, sulfonic acids, aldehydes, and water.
[0015]
Further, specific examples of curing catalysts particularly suitable for epoxy resins include the following. For example, imidazole compounds such as 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole and derivatives thereof; Triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine, methyldiphenylphosphine, dibutylphenylphosphine, tricyclohexylphosphine, 1,2-bis (diphenylphosphino) ) Organic phosphine compounds such as ethane and bis (diphenylphosphino) methane; DBA-DBU (6-dibutylamino-1,8-diazabicyclo (5,4,0) undece) -7), DBU (1,8-diazabicyclo (5,4,0) undecene), DBN (1,5-diazabicyclo [4,3,0] 5-nonene) and the like; tetramethylguanidine, trimethyl Ethanolamine, 2-dimethylamino-2-hydroxypropane, dialkylaminoethanol, N, N′-dimethylpiperazine, N-methylmorpholine, hexamethylenetetramine, 1-hydroxyethyl-2-heptadecylglyoxalidine, pyridine, pyrazine And tertiary amine compounds such as quinoline, benzyldimethylamine, α-methylbenzyldimethylamine, 2- (dimethylaminomethyl) phenol and 2,4,6-tris (dimethylaminomethyl) phenol.
[0016]
These curing catalysts are used alone or as a mixture of two or more as needed. These curing catalysts can also be used as a complex salt with phenol or the like, or as an adduct with a monofunctional or polyfunctional epoxy resin. By using such a complex salt or adduct, the melting point of the core material can be optimized, and the temperature at which the curing catalyst, which is the core material, is released from the capsule can also be set optimally. Further, these curing catalysts can be used after being mixed or impregnated with a solid matrix or a porous body of a chemically stable inorganic material, and then pulverized or stirred in a liquid phase to form particles.
[0017]
Polysilazane is easily ceramified by contacting it with amines and water vapor at a low temperature and then drying in a dry atmosphere. In the treatment, polysilazane is dissolved in an organic solvent to prepare a solution.
[0018]
The organic solvent in this case is not particularly limited, but preferred specific examples include aromatic solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene; n-pentane, i-pentane, and n-pentane. Saturated hydrocarbon compound solvents such as hexane, i-hexane, n-heptane, i-heptane, n-octane and i-octane; ethers such as dipropyl ether and dibutyl ether; ethylcyclohexane, methylcyclohexane, cyclohexane and cyclohexene , P-menthane, decahydronaphthalene, dipentene; and ketones such as MIBK.
[0019]
For example, when triphenylphosphine (TPP) is used as a core material, an aromatic solvent such as benzene or xylene is encapsulated by a chemical method from the viewpoint of particle diameter control, while n-hexane or dibutyl ether is used. Such a solvent can be easily encapsulated even by using a mechanical method.
[0020]
The polysilazane containing the core agent is contacted with amines and water vapor at a low temperature for ceramicization. Specific examples of the amines used herein include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, and propylamine. Amine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, pentylamine, dipentylamine, tripentylamine, hexylamine, dihexylamine, trihexylamine, heptylamine, diheptylamine, octylamine, dioctylamine , Trioctylamine, phenylamine, diphenylamine, triphenylamine and the like (the hydrocarbon chain may be straight-chain or branched-chain). Emissions, alpha-picoline, beta-picoline, .gamma.-picoline, piperidine, lutidine, pyrimidine, pyridazine and the like, further, DBU, DBN and the like.
[0021]
As a method for contacting polysilazane with amines and water vapor, the polysilazane applied to the surface of the core agent is sprayed and exposed to a mixed gas atmosphere of vapors of amines and water vapor (mainly when a mechanical method is used). Immersion in an aqueous solution (mainly when used in a chemical method).
[0022]
When the former method is used, the contact temperature between polysilazane and the vapor of amines and water vapor varies depending on the grade of the polysilazane used, but a type that converts the polysilazane to silica at a low temperature of 100 ° C. or less is preferable. In the latter method, the concentration of amines in the aqueous solution of amines is 0.01 to 80% by weight, preferably 0.1 to 10% by weight, except when tertiary amines are used as the core agent. It is preferable to use a polysilazane of a type which can be converted into silica by treatment at a temperature of 0 ° C to 100 ° C, preferably 10 ° C to 80 ° C.
[0023]
In the present invention, SiO₂The thickness of the shell composed of the layer converted into the above is appropriately set depending on the application, but is preferably in the range of 5 nm to 200 μm, more preferably 10 nm to 10 μm. This is because if the shell thickness exceeds 200 μm, the shell becomes strong, so that it becomes difficult to release the curing catalyst as the core material due to the destruction of the capsule. Conversely, if the shell thickness is less than 5 nm, a sufficient encapsulation effect is obtained. It is because it disappears.
[0024]
In the present invention, the particle size of the particles of the curing catalyst as the core material is appropriately set depending on the application, but is generally in the range of 0.1 μm or more and less than 30 μm. This is because when the thickness is 30 μm or more, the catalytic reaction may be uneven and the characteristics of the cured resin may be varied. On the contrary, when the thickness is less than 0.1 μm, the encapsulation process itself cannot be performed uniformly. This is because the encapsulation effect may not be obtained.
[0025]
Regarding the microcapsule-type curing catalyst of the present invention, there is no particular limitation on the method of breaking the shell and releasing the curing catalyst as the core material. For example, the shell may be agitated with high-speed rotation and high shear force or may be directly compressed to apply external pressure to break the shell. Further, the shell may be broken by increasing the internal pressure by melting or thermally expanding the core material by increasing the temperature. The potential can be exhibited by such a method.
[0026]
ThenFor resin compositionexplain about.The resin composition is, A curable resin and a core containing a curing catalyst are formed of polysilazane-derived SiO_TwoContaining a microcapsule-type curing catalyst coated with a shell made of an inorganic material composed ofIs mentioned.More specifically, for example, a core containing an epoxy resin, a curing agent for the epoxy resin, and a curing catalyst for the epoxy resin is formed of polysilazane-derived SiO 2._TwoAnd a microcapsule-type curing catalyst coated with a shell made of an inorganic material composed of:
[0027]
In addition to epoxy resin,May includeThe curable resin is not particularly limited, and the following are exemplified. For example, styrene, methyl methacrylate, methyl acrylate, vinyl acetate, acrylonitrile, vinylpyrrolidone, maleic anhydride, ethylene, propylene, isobutene, butadiene, isoprene, 1-octene, etc .; , Α-methylstyrene, p-chlorostyrene, 3-methylbutene-1, 4-methylpentene-1, β-pinene, isobutene, isobutyl vinyl ether, N-vinylcarbazole, vinyltrimethylsilyl ether, N-vinylcarbazole, vinyltrimethylsilyl ether , Ethylene oxide, phenylglycidyl ether, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxane, β-propiolactone, ε-caprolactam, Octamethylcyclotetrasiloxane, phenyldiazomethane, novolak; styrene, α-methylstyrene, methyl methacrylate, acrylamide, crotonamide, N-carboxyamino acid anhydride, novolak, etc. for anionic polymerization; cyanoacrylic acid for others Examples include methyl, urea formaldehyde, melamine formaldehyde, nylon, urethane and the like. These may be used alone or as a homopolymer, or two or more of them may be mixed to form a copolymer.
[0028]
Further, particularly as the epoxy resin, specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, phenol or cresol novolac type epoxy resin, An epoxy compound derived from a tri- or tetra (hydroxyphenyl) alkane, a bishydroxybiphenyl-based epoxy resin, and the like can be given. These epoxy resins may be liquid or solid, and the epoxy equivalent is not particularly limited, and they may be used alone or in combination of two or more.
[0029]
Epoxy resinSpecific examples of the curing agent used include the following. For example, polymethylenediamine, polyetherdiamine, diethylenetriamine, iminobispropylamine, bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine, aminoethylethanol Aliphatic polyamine compounds such as amine, methyliminobispropylamine, mensendiamine, N-aminoethylpiperazine, 1,3-diaminocyclohexane, isophoronediamine, m-xylylenediamine, tetrachloro-p-xylylenediamine; m -Phenylenediamine, diaminodiphenyl ether, diaminodiphenylsulfone, 4,4'-methylenedianiline, benzidine, 4,4'-thiodianiline 4,4 ′-(o-toluidine), o-phenylenediamine, dianisidine, methylenebis (o-chloroaniline), bis (3,4-diaminodiphenyl) sulfone, 2,4-toluenediamine, diaminoditolyl sulfone, Aromatic amine compounds such as, 6-diaminopyridine, 4-chloro-o-phenylenediamine, 4-methoxy-6-methyl-m-phenylenediamine and m-aminobenzylamine; N-methylpiperazine, piperidine, hydroxyethylpiperazine , Pyrrolidine, morpholine and other secondary amine compounds; phthalic anhydride, itaconic anhydride, succinic anhydride, citraconic anhydride, alkenyl anhydride, dodecenyl succinic anhydride, tricarballylic anhydride, maleic anhydride, linoleic acid of maleic anhydride Adduct, maleic anhydride- Nyl ether copolymer, maleic anhydride-styrene copolymer, maleic anhydride adduct of methylcyclopentadiene, chlorendic anhydride, alkylated endoalkylenetetrahydrophthalic anhydride, methyl 2-substituted butenyltetrahydrophthalic anhydride, Carboxylic acid anhydrides such as hexahydrophthalic acid, methyltetrahydrophthalic anhydride, pyromellitic anhydride, cyclopentanetetracarboxylic anhydride, benzophenonetetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerin tristrimellitate; phenol novolak; Cresol novolak, nonylphenol novolak, bisphenol F type novolak, bisphenol A type novolak, naphthol type novolak, biphenyl structure-containing novolak, polyvinylphenol Phenol resins such as phenol, phenol aralkyl, dicyclopentadiene / phenol polymer such as phenol, polyparaoxystyrene, polycondensation compound of 2,2'-dimethoxy-p-xylene and phenol monomer; and polyamide resin, polysulfide resin, etc. .
[0030]
Resin compositionMay be appropriately set in accordance with the type and combination of each component. Generally, a curing catalyst is added in an amount of about 0.1 to 50 parts by weight and a curing agent in an amount of about 10 to 200 parts by weight based on 100 parts by weight of the curable resin. That is, if the amount of the curing catalyst is too small, curing may not be performed sufficiently.If the amount of the curing catalyst is too large, the workability and uniformity of mixing during curing, and further, the electrical properties of the cured product may be reduced. It is easy to cause deterioration of characteristics. On the other hand, if the compounding amount of the curing agent is too small, it is difficult to obtain a cured product having good mechanical strength and electrical properties, and if the compounding amount of the curing agent is too large, the curing is insufficient and the mechanical strength and electric characteristics are rather reduced. Tends to be impaired.
[0031]
Further, particularly when an anionic curing catalyst such as an organic phosphine compound, an imidazole compound, or a DBU compound is blended with the epoxy resin, the more preferred blending amount is 0.1 to 10 parts by weight. However, when the above-described curing catalyst is used as an adduct with the epoxy resin, the curing catalyst can be incorporated into the cured product of the resin composition, so that the compounding amount of 10 to 50 parts by weight is preferably used. obtain. Further, it is more preferable that the blending amount of the curing agent with respect to the epoxy resin is set in consideration of the number of functional groups that react with the epoxy group in the curing agent. Specifically, the ratio of the total number of functional groups of the curing agent to the total number of epoxy groups is in the range of 0.6 to 1.4, and the compounding amount in which the total number of epoxy groups and the total number of functional groups are almost equivalent is most preferable.
[0032]
In the resin composition,In order to improve the properties of the cured product, a suitable filler may be mixed. Specific examples of the filler include powders of fused silica, crystalline silica, alumina, magnesia, silicon nitride, aluminum nitride, and boron nitride; inorganic fillers composed of short fibers or long fibers; and organic fillers such as thermoplastic resins. System fillers. These fillers can be used alone or in combination of two or more.
[0033]
In the resin composition,As long as the effects of the present invention are not lost, additives such as a diluent, a flexibility-imparting agent, a release agent, and a coupling agent may be added as needed.
(Embodiment) An embodiment of the present invention will be described below. First, the microcapsule-type curing catalysts (MA1) to (MA4) according to the present invention were prepared as follows. The reagent used was a commercial product, and the reaction was performed under an inert gas atmosphere. The prepared microcapsule-type curing catalyst was used as a composition after spheroidizing to a particle size of 1 to 30 μm. In addition, in the preparation examples herein, the mixing ratio of each component is all converted by weight ratio.
[0034]
(MA1) 20 parts of 2-phenylimidazole pulverized by a pulverizer as a core material to an average particle diameter of 10 μm are mixed and dispersed in 100 parts of a 20% solution of m-xylene of perhydropolysilazane as a shell raw material, and are dispersed. A mixture was made. The hydrophobic mixture was added to 200 parts of water to which 0.1 part of polyoxyethylene nonylphenyl ether was added, and the mixture was dispersed by stirring. To this dispersion was added 10 parts of triethylamine, and the mixture was further stirred for 24 hours. After completion of the reaction, the mixture was washed with water several times, separated using a glass filter or a centrifugal separator, and dried under reduced pressure to obtain a microcapsule-type curing catalyst. The shell thickness averaged 500 nm.
[0035]
(MA2) 30 parts of triphenylphosphine pulverized to a mean particle size of 10 μm by a pulverizer as a core material is mixed and dispersed in 100 parts of a 20% solution of dibutyl ether of perhydropolysilazane as a shell material, and the hydrophobic mixture is dispersed. Produced. The hydrophobic mixture was added to 200 parts of water to which 0.1 part of polyoxyethylene nonylphenyl ether was added, and the mixture was dispersed by stirring. To this dispersion was added 10 parts of triethylamine, and the mixture was further stirred for 24 hours. After completion of the reaction, the mixture was washed with water several times, separated using a glass filter or a centrifugal separator, and dried under reduced pressure to obtain a microcapsule-type curing catalyst. The shell thickness averaged 600 nm.
[0036]
(MA3) 30 parts of DBA-DBU as a core material was mixed with 100 parts of a 20% solution of perhydropolysilazane in cyclohexane, followed by stirring for 30 minutes to prepare a hydrophobic mixture. This mixture was added dropwise to 200 parts of water to which 0.1 part of polyoxyethylene nonylphenyl ether was added, and dispersed by stirring for 24 hours. After completion of the reaction, the mixture was washed with water several times, separated using a glass filter or a centrifugal separator, and dried under reduced pressure to obtain a microcapsule-type curing catalyst. The shell thickness averaged 800 nm.
[0037]
(MA4) A suspension in which 30 parts of triphenylphosphine pulverized by a pulverizer as a core material to an average particle diameter of 10 μm is mixed with and dispersed in 100 parts of a 20% cyclohexane solution of perhydropolysilazane as a shell raw material is prepared. did. This suspension was provided in a supply section of a spray dry granulator, filled with the vapor of an aqueous solution containing 10% of triethylamine, and sprayed and granulated in a room set at 80 ° C. The resulting particles were washed with m-xylene and dried to obtain a microcapsule-type curing catalyst. The shell thickness averaged 800 nm.
[0038]
For comparison, conventional curing accelerators (A1) to (A3) were prepared as follows.
[0039]
(A1) Triphenylphosphine pulverized to have an average particle size of 10 μm was used as it was as a curing catalyst.
[0040]
(A2) 60 parts of triphenylphosphine pulverized to a mean particle size of 10 μm by a pulverizer as a core material was dispersed in 100 parts of hexane together with 0.5 part of a quaternary ammonium surfactant. In this dispersion, 0.2 part of tolylene diisocyanate as a shell material was dissolved and stirred for 30 minutes. After completion of the reaction, the mixture was washed several times with hexane, separated using a glass filter or a centrifugal separator, and dried under reduced pressure to obtain a microcapsule-type curing accelerator. The shell thickness averaged 50 nm.
[0041]
(A3) 2-phenylimidazole pulverized by a pulverizer to an average particle diameter of 10 μm was used as a curing catalyst as it was.
[0042]
(A4) DBA-DBU was used as it was.
Next, a DSC measurement of a sample in which 2 parts of the curing catalysts (MA1) to (MA4) and (A1) to (A4) prepared above were mixed with the same amount mixture of liquid bisphenol F type epoxy resin and methyltetrahydrophthalic anhydride was performed. Then, the peak onset temperature due to the heat generated by curing was examined.
[Table 1]

[Table 2]

Further, the mixture was mixed with a resin, a curing agent, and a filler in the compounding ratio shown in Table 2 to prepare resin compositions of Examples (1) to (6) and Comparative Examples (1) to (4). As a preparation method, Examples (1) to (4) and Comparative Examples (1) to (3) were uniformly mixed by a Henschel mixer, and then mixed by a hot roll set at about 100 ° C. for 3 minutes. Examples (5) and (6) and Comparative Example (4) were prepared by mixing with a mixer and passing through three rolls three times.
[0043]
For each of the obtained resin compositions, the storage stability was evaluated by measuring the viscosity immediately after preparation and after storing at 40 ° C. for one month. The evaluation criteria are as follows. That is, the viscosity after storage was compared with the value immediately after preparation, and the case where there was no change was “excellent”, the case of 2 times or less was “good”, and the case of showing 2 times or more change was “impossible” .
[0044]
In each of the resin compositions, (1) Examples (1) to (4) and Comparative Examples (1) to (3) were subjected to 175 ° C. for 3 minutes, and further to 180 ° C. for 8 hours as an after cure, (2) The compositions of Examples (5) and (6) and Comparative Example (4) were cured at 150 ° C. for 4 hours, and the flexural strength of the cured product was measured. Regarding curability, in the case of (1), the Barcol hardness of the molded product immediately after opening the mold at 175 ° C. for 3 minutes, and in the case of (2), potting the composition on a metal plate and immediately after curing at a predetermined temperature Was determined by Barcol hardness. Table 3 shows the results.
[Table 3]

In addition, the symbols of the resin, the curing agent, and the filler in Table 2 represent the following materials.
resin
(Epoxy resin A) Cresol novolak type epoxy resin
(Epoxy resin B) Liquid bisphenol F type epoxy resin
Curing agent
(Curing agent A) Cresol novolak resin
(Curing agent B) Methyltetrahydrophthalic anhydride
filler
(F1) fused silica powder, average particle size 20 μm
(F2) fused silica powder, average particle size 5 μm
Pigment
Carbon black
Surface treatment agent
γ-glycidyl propyl trimethoxysilane
Release agent
Carnauba wax
As shown in Table 1, it can be seen that the microcapsule encapsulation of the catalyst increases the curing start temperature and shows the potential. Furthermore, as shown in Table 2, the resin composition of Comparative Example (2) shows latent curability from the results of DSC measurement, but has no long-term storage stability. In the resin composition of (6), the change in viscosity after long-term storage is small, and the storage stability is excellent. Further, since the shell material remains as an inorganic filler even after the resin composition is cured, it can be said that the shell material does not act as an impurity when used for semiconductor encapsulation.
[0045]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a microcapsule-type curing catalyst in which a core containing a curing catalyst is coated with a shell made of an inorganic material composed of polysilazane-derived SiO 2, Utilizing water resistance and heat resistance, high storage stability can be achieved regardless of the type of curing agent used. Further, a resin composition containing such a microcapsule-type curing catalyst and exhibiting a stable curing start temperature can be provided. Furthermore, since the shell remaining after curing is an inorganic material, it does not elute impurities, and acts similarly to the inorganic filler, so that the reliability as a cured product can be improved.

Claims (2)

  A step of allowing polysilazane to exist on the surface of the curing catalyst;
  Contacting the polysilazane on the curing catalyst surface with amines and water vapor at a temperature of 100 ° C. or less, _Two The curing catalyst is converted to SiO 2 _Two A method for producing a microcapsule-type curing catalyst, comprising:   A method for producing a microcapsule-type curing catalyst, wherein the curing catalyst according to claim 1 is an imidazole compound, an organic phosphine compound, or a DBU compound.