JP3882871B2 - Process for producing alkenylphenol copolymer - Google Patents

Description

（式中、Ｒ¹は水素原子又はメチル基を表し、Ｒ²は炭素数が１〜６のアルキル基を表す）で表されるフェノール残基の水酸基が飽和脂肪族系保護基により保護された化合物と、アクリル酸エステル又はメタクリル酸エステルとを共重合させて得られる共重合体から、飽和脂肪族系保護基を脱離させてアルケニルフェノール系共重合体を得る方法において、脱離剤として下記一般式（II）
ＸＨＳＯ₄ ……（II）
（式中、Ｘはアルカリ金属を表す）で表される重硫酸塩を用いるアルケニルフェノール系共重合体の製造方法や、上記一般式（Ｉ）で表されるフェノール残基の水酸基が飽和脂肪族系保護基により保護された化合物と、ビニル芳香族化合物と、アクリル酸エステル又はメタクリル酸エステルとを共重合させて得られる共重合体から、飽和脂肪族系保護基を脱離させてアルケニルフェノール系共重合体を得る方法において、脱離剤として上記一般式（II）で表される重硫酸塩を用いるアルケニルフェノール系共重合体の製造方法に関する。
【０００７】
また本発明は、アクリル酸エステルがｔ−ブチルアクリレートであり、メタクリル酸エステルがｔ−ブチルメタクリレートである上記アルケニルフェノール共重合体の製造方法や、共重合体がランダム共重合体又はブロック共重合体である上記アルケニルフェノール系共重合体の製造方法や、上記一般式（II）におけるＸが、リチウム、カリウム、又はナトリウムのいずれかである上記アルケニルフェノール系共重合体の製造方法や、一般式（II）で表される重硫酸塩の添加量が、共重合体１００重量部に対して０．１〜１００重量部である上記アルケニルフェノール系共重合体の製造方法に関する。
【０００８】
【発明の実施の形態】
本発明において用いられる一般式（Ｉ）で表される化合物としては、ｐ−ｎ−ブトキシスチレン、ｐ−ｓｅｃ−ブトキシスチレン、ｐ−ｔｅｒｔ−ブトキシスチレン、ｐ−ｔｅｒｔ−ブトキシ−α−メチルスチレン、ｍ−ｔｅｒｔ−ブトキシスチレン、ｍ−ｔｅｒｔ−ブトキシ−α―メチルスチレン等が例示され、これらは一種単独又は二種以上の混合物として使用することができる。
【０００９】
本発明において用いられるビニル芳香族化合物としては、スチレン、ｏ−メチルスチレン、ｐ−メチルスチレン、ｐ−ｔｅｒｔ−ブチルスチレン、α−メチルスチレンなどが挙げられ、これらは一種単独又は二種以上の混合物として使用することができる。
【００１０】
（メタ）アクリル酸エステルとしては、メチルアクリレート、メチルメタクリレート、ｎ−プロピルアクリレート、ｎ−ブチルアクリレート、ｎ−ブチルメタクリレート、ｓｅｃ−ブチルアクリレート、ｔ−ブチルアクリレート、ｔ−ブチルメタクリレート、シクロヘキシルアクリレート、テトラヒドロフラニルアクリレート、テトラヒドロピラニルアクリレート、テトラヒドロピラニルメタクリレート、３−オキソシクロヘキシルアクリレート、１−アダマンチルアクリレート、２−メチル−２−アダマンチルアクリレート、２−メチル−２−アダマンチルメタクリレート、イソボルニルアクリレート、ノルボルナンアクリレートなどが例示されるが、中でも、ＥＳＣＡＰ型レジスト用ポリマーの（メタ）アクリル酸エステル成分として好適なｔ−ブチルアクリレート、ｔ−ブチルメタクリレート、テトラヒドロピラニルアクリレート、テトラヒドロピラニルメタクリレートが好ましい。これらは、一種単独又は二種以上の混合物として使用することができる。
【００１１】
本発明の共重合体の製造には、公知のアニオン重合法又はラジカル重合法を適用することができる。
アニオン重合法は、アルカリ金属又は有機アルカリ金属を重合開始剤として、前記一般式（Ｉ）で示される化合物をアニオン重合するか、あるいは該化合物とビニル芳香族化合物とを併用してアニオン重合を行い、ついで反応系に（メタ）アクリル酸エステルを逐次添加して共重合反応が行われるが、この反応は通常窒素、アルゴン等の不活性ガス雰囲気下、有機溶媒中において、−１００〜５０℃の温度で行われる。この方法においては、モノマー類を逐次添加することによりブロック共重合体が、また、前記一般式（Ｉ）で示される化合物とビニル芳香族化合物との混合物を反応系に添加してランダム共重合を行った後、（メタ）アクリル酸エステルを添加して重合を継続することにより部分ブロック共重合体が得られる。
【００１２】
上記重合開始剤のアルカリ金属としては、リチウム、ナトリウム、カリウム、セシウム等が例示される。また、有機アルカリ金属としては、上記アルカリ金属のアルキル化物、アリル化物、アリール化物等が使用可能であり、具体的には、エチルリチウム、ｎ−ブチルリチウム、ｓｅｃ−ブチルリチウム、ｔｅｒｔ−ブチルリチウム、エチルナトリウム、リチウムビフェニル、リチウムナフタレン、リチウムトリフェニル、ナトリウムナフタレン、α−メチルスチレンナトリウムジアニオン、１，１−ジフェニルヘキシルリチウム、１，１−ジフェニル−３−メチルペンチルリチウム等を例示することができる。
【００１３】
また、有機溶媒としては、ｎ−ヘキサン、ｎ−ヘプタン等の脂肪族炭化水素類、シクロヘキサン、シクロペンタン等の脂環族炭化水素類、ベンゼン、トルエン等の芳香族炭化水素類、ジエチルエーテル、テトラヒドロフラン、ジオキサン等のエーテル類の他、アニソール、ヘキサメチルホスホルアミド等の通常アニオン重合において使用される有機溶媒の一種単独又は二種以上の混合溶媒を使用することができる。
【００１４】
ラジカル重合法は、アゾビスイソブチロニトリル、アゾビスイソバレロニトリル等のアゾ化合物や、過酸化ベンゾイル、メチルエチルケトンパーオキサイド、クメンハイドロパーオキサイド等の有機過酸化物のような公知のラジカル重合開始剤を用い、必要に応じて１−ドデカンチオール等の公知の連鎖移動剤を併用して、通常ベンゼン、トルエン等の芳香族炭化水素類、エチレングリコールモノブチルエーテル、エチレングリコールモノエチルエーテルアセテート、プロピレングリコールモノメチルエーテル、プロピレングリコールモノエチルエーテル等の多価アルコール誘導体類などの有機溶媒中において、窒素、アルゴン等の不活性ガス雰囲気下、５０〜２００℃の温度で行われる。
【００１５】
この方法においては、全モノマーを混合物として反応系に添加することによりランダム共重合体が、いずれかのモノマーの全部又は一部を後から添加することによりテーバブロック共重合体が得られる。また、ＴＥＭＰＯ（２，２，６，６−テトラメチルピペリジン−１−オキシル）を用いたラジカル重合法やＣｕ（Ｉ）／Ｃｕ（II）レドックスプロセスを用いた原子移動ラジカル重合法などのいわゆるリビングラジカル重合法により得られる、前記構成成分からなる共重合体も本発明に包含される。
【００１６】
次に、アニオン重合法又はラジカル重合法により得られる共重合体から飽和脂肪族系保護基のみを選択的に脱離させ、アルケニルフェノール骨格を生成せしめる反応は、通常、溶媒の存在下、下記一般式（II）
ＸＨＳＯ₄ ……（II）
（式中、Ｘはアルカリ金属を表す）で表される重硫酸塩を加えて、室温〜１５０℃の温度で行われる。溶媒としては、ｎ−ヘキサン、ｎ−ヘプタンなどの脂肪族炭化水素類、シクロヘキサン、シクロペンタン等の脂環族炭化水素類、ベンゼン、トルエン等の芳香族炭化水素類、メタノール、エタノールなどのアルコール類、メチルエチルケトンなどのケトン類、メチルセロソルブ、エチルセロソルブなどの多価アルコール誘導体類、水などの一種又は二種以上の混合溶媒が用いられる。
【００１７】
上記一般式（II）で表される重硫酸塩としては、硫酸水素リチウム、硫酸水素カリウム、硫酸水素ナトリウムなどのアルカリ金属塩の一種又は二種以上の混合物が使用することができるが、その中でも特にカリウム塩、ナトリウム塩が好ましい。重硫酸塩の添加量は、前記共重合体中に含まれる飽和脂肪族系保護基のモル数、（メタ）アクリル酸エステルの種類、共重合体中の（メタ）アクリル酸エステルの含有量、共重合体の分子量、共重合形態等によって適宜選択することができるが、通常、共重合体１００重量部に対して重硫酸塩０．１〜１００重量部を用いることが好ましい。この反応において、共重合体の構造に応じて重硫酸塩の添加量を調節することにより、（メタ）アクリル酸エステルとしてｔ−ブチル（メタ）アクリレート、テトラヒドロピラニル（メタ）アクリレートなどの加水分解しやすいコモノマーを用いても、エステル部分の加水分解を起こすことなく飽和脂肪族系保護基のみが選択的に脱離されて、本発明のアルケニルフェノール系共重合体が得られる。
【００１８】
【実施例】
以下に、実施例を挙げて本発明を更に具体的に説明するが、本発明の範囲はこれらの例示に限定されるものではない。
実施例１
窒素雰囲気下において、テトラヒドロフラン［以下「ＴＨＦ」と略す］１５００ｇ中に、ｎ−ブチルリチウム［以下「ＮＢＬ」と略す］３０ミリモルを加え、撹拌下、−６０℃に保持しながら、ｐ−ｔｅｒｔ−ブトキシスチレン［以下「ＰＴＢＳＴ」と略す］１．０モルを１時間かけて滴下し、さらに反応を１時間継続し、ガスクロマトグラフィー［以下「ＧＣ」と略す］により反応が完結したことを確認した。この段階で反応系から少量を採取し、メタノールにより反応を停止させた後、ゲルパーミィエイションクロマトグラフィー［以下「ＧＰＣ」と略す］により分析したところ、得られたＰＴＢＳＴポリマーは、Ｍｎ＝７３００、Ｍｗ／Ｍｎ＝１．０８の単分散ポリマーであった。この反応系にｔｅｒｔ−ブチルメタクリレート［以下「ｔ−ＢＭＡ」と略す］０．５モルを１時間かけて滴下し、さらに反応を１時間継続して、ＧＣにより反応が完結したことを確認した。次いで、反応系にメタノールを加えて反応を停止させ、反応液を大量のメタノール中に投入してポリマーを析出させ、濾過、洗浄後、６０℃で１５時間減圧乾燥して白色粉体状のポリマーを得た。用いたモノマー総量に対する重合収率は９９．５％であった。このポリマーのＧＰＣ分析を行ったところ、Ｍｎ＝９５４０、Ｍｗ／Ｍｎ＝１．１５の単分散ポリマーであった。
【００１９】
次に、得られたポリマー１０ｇをトルエン／エタノール＝１／２（重量比）の混合溶媒に溶解して２５％溶液とし、硫酸水素カリウム２ｇを加えて７５℃で反応を行った。反応経過は赤外線吸収スペクトル［以下「ＩＲ」と略す］で追跡し、ポリＰＴＢＳＴセグメントのｔ−ブトキシ基由来８９０ｃｍの吸収が３．５時間後に消失したので終点とした。次いで、反応液を濾過して硫酸水素カリウムを除去した後、濾液から溶媒分を減圧溜去して白色粉体状のポリマー７．６ｇを得た。この反応において、反応前後におけるポリマーの¹³Ｃ ＮＭＲ［以下「ＮＭＲ」と略す］を測定した結果、７７ｐｐｍ付近におけるポリＰＴＢＳＴのｔ−ブトキシ基由来のピークが反応後は消失しており、一方、２７ｐｐｍ付近のポリｔ−ＢＭＡのｔ−ブチル基由来のピークは、ベンゼン環カーボンに対する面積比が反応前後において変化していなかった。また、１７７〜１７８ｐｐｍ付近のカルボキシル基由来のブロードなピークは全く観察されなかった。また、生成したポリマーについてＧＰＣを測定したところ、Ｍｎ＝７２５０、Ｍｗ／Ｍｎ＝１．１５の単分散ポリマーであり、ＮＭＲにより測定した共重合比率は、ｐ−ヒドロキシスチレン単位／ｔ−ＢＭＡ単位＝１／０．５（モル比）であった。
以上のことから、共重合反応及びその後の選択的な脱離反応は設定どうりに行われ、ｐ−ヒドロキシスチレンセグメントとｔ−ＢＭＡセグメントとからなるアルケニルフェノール系ブロック共重合体が生成したことを確認した。
【００２０】
実施例２
窒素雰囲気下において、ＴＨＦ２０００ｇ中に、ＮＢＬ２９ミリモルを加え、撹拌下、−５０℃に保持しながら、ＰＴＢＳＴ１モルとスチレン０．３モルとの混合物を１時間かけて滴下し、更に１時間反応を継続し、ＧＣにより反応完結を確認した。この段階でのＰＴＢＳＴ／スチレン系ポリマーは、Ｍｎ＝１１０００、Ｍｗ／Ｍｎ＝１．０５の単分散ポリマーであった。次いで、反応系に塩化リチウム１５０ミリモルを加えた後、ｔｅｒｔ−ブチルアクリレート［以下「ｔ−ＢＡ」と略す］０．３モルを１時間かけて滴下、更に反応を１時間継続して、ＧＣにより反応が完結したことを確認した。次に、反応系にメタノールを加えて反応を停止させ、反応液を大量のメタノール中に投入してポリマーを析出させ、濾過、洗浄後、６０℃で１５時間減圧乾燥して白色粉体状のポリマーを得た。用いたモノマー総量に対する重合収率は９９．３％であった。このポリマーのＧＰＣ分析を行ったところ、Ｍｎ＝１２５３０、Ｍｗ／Ｍｎ＝１．１３の単分散ポリマーであった。
【００２１】
次に、得られたポリマー１０ｇをプロピレングリコールモノエチルエーテルに溶解して２５％溶液とし、硫酸水素カリウム０．２ｇを加えて９０℃で反応を行った。反応経過の追跡は実施例１と同様に行ったところ、５時間後に終点に達した。反応液を濾過して硫酸水素カリウムを除去した後、濾液から溶媒分を減圧溜去して白色粉体状のポリマー７．５ｇを得た。この反応において、反応前後におけるポリマーのＮＭＲを測定したところ、実施例１におけると同様に、ポリＰＴＢＳＴのｔ−ブトキシ基由来のピークの消失、ポリｔ−ＢＡのｔ−ブチル基由来のピークには変化のないこと、新たにカルボキシル基由来のピークが出現しないことが確認された。また、生成したポリマーについてＧＰＣを測定した結果、Ｍｎ＝９５２０、Ｍｗ／Ｍｎ＝１．１３の単分散ポリマーであり、ＮＭＲにより測定した共重合比率は、ｐ−ヒドロキシスチレン単位／スチレン単位／ｔ−ＢＡ単位＝１／０．３／０．３（モル比）であった。
以上のことから、共重合反応及び選択的な脱離反応は設定どうりに行われ、ｐ−ヒドロキシスチレンセグメントとスチレンセグメントとｔ−ＢＡセグメントとからなるアルケニルフェノール系部分ブロック共重合体が生成したことを確認した。
【００２２】
実施例３
窒素雰囲気下において、プロピレングリコールモノエチルエーテル２８０ｇ中に、ＰＴＢＳＴ ０．７１モル、ｔ−ＢＡ ０．１１モル、アゾビスイソブチロニトリル０．０５モル、１−ドデカンチオール ０．００７モルを加えて、撹拌下、７０℃で５時間、更に８５℃で５時間反応を行った。次いで、反応液に、反応液と同量のヘキサン、倍量のメタノール及び少量の水を加えて分液精製により未反応のモノマーを除去した後、ポリマー層から溶媒分を減圧溜去して淡褐色粉体状のポリマーを得た。用いたモノマー総量に対する収率は８８．６％であった。このポリマーのＧＰＣ分析を行ったところ、Ｍｎ＝８５００，Ｍｗ／Ｍｎ＝１．４５の単峰性のポリマーであった。
【００２３】
次に、得られたポリマー１０ｇをプロピレングリコールモノエチルエーテルに溶解して２０％溶液とし、硫酸水素カリウム０．１ｇを加えて１００℃で反応を行った。反応経過の追跡は実施例１と同様に行ったところ、４時間後に終点に達した。反応液を濾過して硫酸水素カリウムを除去した後、大量の水中に投入してポリマーを析出させ、濾過、洗浄後、８０℃で１５時間減圧乾燥して淡褐色粉体状のポリマー６．３ｇを得た。この反応において、反応前後におけるポリマーのＩＲ及びＮＭＲを測定したところ、実施例１におけると同様に、ポリＰＴＢＳＴのｔ−ブトキシ基由来のピークの消失、ポリｔ−ＢＡのｔ−ブチル基由来のピークには全く変化のないこと、新たにカルボキシル基由来のピークが出現しないことが確認された。また、生成したポリマーについてＧＰＣを測定した結果、Ｍｎ＝６０６０、Ｍｗ／Ｍｎ＝１．４６の単峰性ポリマーであり、ＮＭＲにより測定した共重合比率は、ｐ−ヒドロキシスチレン単位／ｔ−ＢＡ単位＝１／０．１５（モル比）であった。
以上のことから、共重合反応及び選択的な脱離反応は設定どうりに行われ、ｐ−ヒドロキシスチレンセグメントとｔ−ＢＡセグメントとからなるアルケニルフェノール系ランダム共重合体が生成したことを確認した。
【００２４】
比較例１
実施例１で得られたＰＴＢＳＴとｔ−ＢＭＡとの共重合体１０ｇをトルエン／エタノール＝１／１（重量比）混合溶媒に溶解して２５％溶液とし、３５％濃塩酸１ｇを加えて６５℃で反応を行った。反応経過の追跡は実施例１と同様に行ったところ７時間後に終点に達した。反応液を水洗して濃塩酸を除去し、大量の水中に投入してポリマーを析出させた。濾過、洗浄後、６５℃で１５時間減圧乾燥を行って白色粉体状のポリマー６．２ｇを得た。得られたポリマーをＮＭＲで分析した結果、ポリＰＴＢＳＴのｔ−ブトキシ基由来のピークの消失は確認されたが、ベンゼン環カーボンに対するｔ−ＢＭＡのｔ−ブチル基の面積比が減少しており、且つ新たに１７７〜１７８ｐｐｍにカルボキシル基由来のブロードなピークが出現した。このことから、ｔ−ＢＭＡセグメントの一部が加水分解しメタアクリル酸セグメントが生成したことが確認された。
【００２５】
比較例２
実施例３で得られたＰＴＢＳＴとｔ−ＢＡとの共重合体１０ｇをプロピレングリコールモノエチルエーテルに溶解して２０％溶液とし、濃硫酸０．０１ｇを加えて７５℃で反応を行った。反応経過の追跡は実施例１と同様に行ったところ、５時間後に終点に達した。反応液を水洗して濃硫酸を除去し、大量の水中に投入してポリマーを析出させた。濾過、洗浄後、６５℃で１５時間減圧乾燥を行って淡褐色粉体状のポリマー５．７ｇを得た。得られたポリマーをＮＭＲで分析した結果、ポリＰＴＢＳＴのｔ−ブトキシ基由来のピークの消失は確認されたが、ベンゼン環カーボンに対するｔ−ＢＡのｔ−ブチル基の面積比が減少しており、且つ新たに１７７〜１７８ｐｐｍにカルボキシル基由来のブロードなピークが出現した。このことから、ｔ−ＢＡセグメントの一部が加水分解しアクリル酸セグメントが生成したことが確認された。
【００２６】
【発明の効果】
本発明によると、アルケニルフェノールのフェノール残基の水酸基が飽和脂肪族系保護基により保護された化合物と、（メタ）アクリル酸エステルと、必要に応じて用いられるビニル芳香族化合物とを共重合させて得られる共重合体から、飽和脂肪族系保護基のみを選択的に脱離させることができ、ＥＳＣＡＰ型レジスト用として実用に供することができない（メタ）アクリル酸骨格、すなわちカルボキシル基を有する共重合体の生成を伴うことなく、ＥＳＣＡＰ型レジスト用として有用なアルケニルフェノール系共重合体を製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an alkenylphenol copolymer, which is expected to be used as an excimer laser resist material, and more specifically, a compound in which a hydroxyl group of a phenol residue is protected with a saturated aliphatic protecting group, and t -A copolymer obtained from butyl acrylate or t-butyl methacrylate [hereinafter abbreviated as "t-butyl (meth) acrylate"] is obtained by removing only saturated aliphatic protecting groups using a specific reagent. The present invention relates to a method for producing a alkenylphenol-based copolymer.
[0002]
[Prior art]
Conventionally, homopolymers and copolymers of alkenylphenols typified by poly-p-hydroxystyrene have been useful as chemically amplified and excimer laser resist materials, especially acrylic esters or methacrylic esters [hereinafter “(meth) acrylic acid”. A resist using a copolymer having t-butyl (meth) acrylate as a comonomer as “ester” is known as a so-called ESCAP resist capable of high resolution. And as a copolymer of p-hydroxystyrene and t-butyl (meth) acrylate, those obtained by thermal polymerization of a vinylphenol monomer and t-butyl (meth) acrylate, p-acetoxystyrene and t- A product obtained by copolymerizing butyl (meth) acrylate with a radical polymerization method and then selectively hydrolyzing only an acetoxy group using a small amount of an acidic reagent or an alkaline reagent is already commercially available.
[0003]
On the other hand, when a compound in which the hydroxyl group of the phenol residue is protected by a saturated aliphatic protecting group is used as a precursor for forming an alkenylphenol skeleton, even if it is a trace amount when using a normal acidic reagent, for example, hydrochloric acid, Along with the elimination reaction of the saturated aliphatic protecting group, the hydrolysis reaction of the ester portion of the t-butyl (meth) acrylate skeleton is caused. As a result, the alkenylphenol skeleton, the t-butyl (meth) acrylate skeleton, and the (meta ) A copolymer comprising an acrylic acid skeleton is produced. When a (meth) acrylic acid skeleton, that is, a copolymer having a carboxyl group is used for resists, it has a great influence on the alkali dissolution rate, so that it cannot be put to practical use for ESCAP type resists.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a copolymer obtained by copolymerizing a compound in which a hydroxyl group of a phenol residue is protected with a saturated aliphatic protecting group and a (meth) acrylic acid ester, or a hydroxyl group of a phenol residue is saturated. From a copolymer obtained by copolymerizing a compound protected with an aliphatic protecting group, a vinyl aromatic compound, and a (meth) acrylate ester, only a saturated aliphatic protecting group is selectively removed. An object of the present invention is to provide a method for producing an alkenylphenol-based copolymer substantially free of a (meth) acrylic acid skeleton.
[0005]
[Means for Solving the Problems]
As a result of diligent research to solve the above-mentioned problems, the present inventors have found that a hydroxyl group of a phenol residue of alkenylphenol is protected by a saturated aliphatic protecting group, a (meth) acrylic acid ester, and if necessary. By treating a copolymer obtained by copolymerizing with a vinyl aromatic compound used with a specific acidic reagent, only a saturated aliphatic protective group is obtained without causing hydrolysis of the ester moiety. The inventors have found that they can be selectively desorbed and have completed the present invention.
[0006]
That is, the present invention provides the following general formula (I)
[Chemical 3]

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 6 carbon atoms). The hydroxyl group of the phenol residue represented by this is protected by a saturated aliphatic protecting group. In the method for obtaining an alkenylphenol copolymer by removing a saturated aliphatic protecting group from a copolymer obtained by copolymerizing a compound and an acrylate ester or a methacrylate ester, Formula (II)
XHSO ₄ (II)
(Wherein X represents an alkali metal), a method for producing an alkenylphenol-based copolymer using a bisulfate salt, or a hydroxyl group of a phenol residue represented by the above general formula (I) is saturated aliphatic An alkenylphenol group by removing a saturated aliphatic protecting group from a copolymer obtained by copolymerizing a compound protected with a protecting group, a vinyl aromatic compound, and an acrylic ester or methacrylic ester. The present invention relates to a method for producing an alkenylphenol copolymer using a bisulfate represented by the above general formula (II) as a releasing agent in a method for obtaining a copolymer.
[0007]
The present invention also provides a method for producing the alkenylphenol copolymer, wherein the acrylic ester is t-butyl acrylate and the methacrylic ester is t-butyl methacrylate, and the copolymer is a random copolymer or a block copolymer. The method for producing the alkenylphenol-based copolymer, the method for producing the alkenylphenol-based copolymer in which X in the general formula (II) is any one of lithium, potassium, or sodium, It is related with the manufacturing method of the said alkenyl phenol type copolymer whose addition amount of bisulfate represented by II) is 0.1-100 weight part with respect to 100 weight part of copolymers.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the compound represented by the general formula (I) used in the present invention include pn-butoxystyrene, p-sec-butoxystyrene, p-tert-butoxystyrene, p-tert-butoxy-α-methylstyrene, Examples include m-tert-butoxystyrene, m-tert-butoxy-α-methylstyrene, and the like can be used singly or as a mixture of two or more.
[0009]
Examples of the vinyl aromatic compound used in the present invention include styrene, o-methyl styrene, p-methyl styrene, p-tert-butyl styrene, α-methyl styrene, and the like. These are one kind alone or a mixture of two or more kinds. Can be used as
[0010]
(Meth) acrylic acid esters include methyl acrylate, methyl methacrylate, n-propyl acrylate, n-butyl acrylate, n-butyl methacrylate, sec-butyl acrylate, t-butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, tetrahydrofuranyl Acrylate, tetrahydropyranyl acrylate, tetrahydropyranyl methacrylate, 3-oxocyclohexyl acrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, isobornyl acrylate, norbornane acrylate, etc. Among them, among them, it is preferable as a (meth) acrylic acid ester component of ESCAP type resist polymer. Do t-butyl acrylate, t- butyl methacrylate, tetrahydropyranyl acrylate, tetrahydropyranyl methacrylate are preferred. These can be used alone or as a mixture of two or more.
[0011]
A known anionic polymerization method or radical polymerization method can be applied to the production of the copolymer of the present invention.
In the anionic polymerization method, the compound represented by the general formula (I) is anionically polymerized using an alkali metal or an organic alkali metal as a polymerization initiator, or the compound and the vinyl aromatic compound are used in combination for anion polymerization. Then, a copolymerization reaction is carried out by sequentially adding (meth) acrylic acid ester to the reaction system. This reaction is usually carried out at −100 to 50 ° C. in an organic solvent under an inert gas atmosphere such as nitrogen and argon. Done at temperature. In this method, a block copolymer is added by sequentially adding monomers, and a mixture of the compound represented by the general formula (I) and a vinyl aromatic compound is added to the reaction system to carry out random copolymerization. After performing, a partial block copolymer is obtained by adding (meth) acrylic acid ester and continuing superposition | polymerization.
[0012]
Examples of the alkali metal of the polymerization initiator include lithium, sodium, potassium, cesium and the like. Further, as the organic alkali metal, alkylated products, allylated products, arylated products and the like of the above alkali metals can be used. Specifically, ethyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, Examples include ethyl sodium, lithium biphenyl, lithium naphthalene, lithium triphenyl, sodium naphthalene, α-methylstyrene sodium dianion, 1,1-diphenylhexyl lithium, 1,1-diphenyl-3-methylpentyl lithium, and the like.
[0013]
Examples of the organic solvent include aliphatic hydrocarbons such as n-hexane and n-heptane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, aromatic hydrocarbons such as benzene and toluene, diethyl ether, and tetrahydrofuran. In addition to ethers such as dioxane, organic solvents such as anisole and hexamethylphosphoramide, which are usually used in anionic polymerization, may be used alone or in combination of two or more.
[0014]
Radical polymerization methods are known radical polymerization initiators such as azo compounds such as azobisisobutyronitrile and azobisisovaleronitrile, and organic peroxides such as benzoyl peroxide, methyl ethyl ketone peroxide and cumene hydroperoxide. And optionally using a known chain transfer agent such as 1-dodecanethiol, usually aromatic hydrocarbons such as benzene and toluene, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl In an organic solvent such as polyhydric alcohol derivatives such as ether and propylene glycol monoethyl ether, the reaction is performed at a temperature of 50 to 200 ° C. under an inert gas atmosphere such as nitrogen and argon.
[0015]
In this method, a random copolymer is obtained by adding all the monomers as a mixture to the reaction system, and a taber block copolymer is obtained by adding all or part of any of the monomers later. In addition, a so-called living such as a radical polymerization method using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and an atom transfer radical polymerization method using a Cu (I) / Cu (II) redox process. Copolymers comprising the above components obtained by radical polymerization are also included in the present invention.
[0016]
Next, the reaction for selectively removing only a saturated aliphatic protecting group from a copolymer obtained by an anionic polymerization method or a radical polymerization method to form an alkenylphenol skeleton is usually carried out in the presence of a solvent as described below. Formula (II)
XHSO ₄ (II)
(Wherein X represents an alkali metal) is added, and the reaction is performed at a temperature of room temperature to 150 ° C. Examples of the solvent include aliphatic hydrocarbons such as n-hexane and n-heptane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, aromatic hydrocarbons such as benzene and toluene, and alcohols such as methanol and ethanol. , Ketones such as methyl ethyl ketone, polyhydric alcohol derivatives such as methyl cellosolve and ethyl cellosolve, and one or more mixed solvents such as water are used.
[0017]
As the bisulfate represented by the general formula (II), one or a mixture of two or more alkali metal salts such as lithium hydrogen sulfate, potassium hydrogen sulfate, and sodium hydrogen sulfate can be used. In particular, potassium salt and sodium salt are preferable. The amount of bisulfate added is the number of moles of saturated aliphatic protecting groups contained in the copolymer, the type of (meth) acrylic acid ester, the content of (meth) acrylic acid ester in the copolymer, Although it can select suitably by the molecular weight of a copolymer, a copolymerization form, etc., it is preferable to use normally 0.1-100 weight part of bisulfates with respect to 100 weight part of copolymers. In this reaction, hydrolysis of t-butyl (meth) acrylate, tetrahydropyranyl (meth) acrylate, etc. as (meth) acrylic acid ester is controlled by adjusting the amount of bisulfate added according to the structure of the copolymer. Even when a comonomer that is easy to be used is used, only the saturated aliphatic protecting group is selectively removed without causing hydrolysis of the ester moiety, and the alkenylphenol copolymer of the present invention is obtained.
[0018]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to these examples.
Example 1
Under a nitrogen atmosphere, 30 mmol of n-butyllithium [hereinafter abbreviated as “NBL”] is added to 1500 g of tetrahydrofuran [hereinafter abbreviated as “THF”], and the mixture is kept at −60 ° C. with stirring. 1.0 mol of butoxystyrene [hereinafter abbreviated as “PTBST”] was added dropwise over 1 hour, and the reaction was further continued for 1 hour. It was confirmed that the reaction was completed by gas chromatography [hereinafter abbreviated as “GC”]. . A small amount was collected from the reaction system at this stage, the reaction was stopped with methanol, and then analyzed by gel permeation chromatography [hereinafter abbreviated as “GPC”]. As a result, the obtained PTBST polymer had Mn = 7300. , Mw / Mn = 1.08. To this reaction system, 0.5 mol of tert-butyl methacrylate [hereinafter abbreviated as “t-BMA”] was added dropwise over 1 hour, and the reaction was further continued for 1 hour to confirm that the reaction was completed by GC. Next, methanol is added to the reaction system to stop the reaction, the reaction solution is poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 15 hours to give a white powdery polymer. Got. The polymerization yield based on the total amount of monomers used was 99.5%. As a result of GPC analysis of this polymer, it was a monodisperse polymer with Mn = 9540 and Mw / Mn = 1.15.
[0019]
Next, 10 g of the obtained polymer was dissolved in a mixed solvent of toluene / ethanol = 1/2 (weight ratio) to obtain a 25% solution, and 2 g of potassium hydrogen sulfate was added to react at 75 ° C. The course of the reaction was followed by an infrared absorption spectrum [hereinafter abbreviated as “IR”], and the end point was determined because the absorption of 890 cm derived from the t-butoxy group of the poly PTBST segment disappeared after 3.5 hours. Next, the reaction solution was filtered to remove potassium hydrogen sulfate, and then the solvent was removed from the filtrate under reduced pressure to obtain 7.6 g of a white powdery polymer. In this reaction, as a result of measuring ¹³ C NMR of the polymer before and after the reaction [hereinafter abbreviated as “NMR”], a peak derived from the t-butoxy group of polyPTBST in the vicinity of 77 ppm disappeared after the reaction, whereas 27 ppm In the peak derived from the t-butyl group of the nearby poly t-BMA, the area ratio to the benzene ring carbon did not change before and after the reaction. In addition, a broad peak derived from a carboxyl group near 177 to 178 ppm was not observed at all. Moreover, when GPC was measured about the produced | generated polymer, it is a monodispersed polymer of Mn = 7250 and Mw / Mn = 1.15, and the copolymerization ratio measured by NMR is p-hydroxystyrene unit / t-BMA unit = It was 1 / 0.5 (molar ratio).
From the above, the copolymerization reaction and the subsequent selective elimination reaction were carried out as set up, and it was confirmed that an alkenylphenol block copolymer composed of a p-hydroxystyrene segment and a t-BMA segment was produced. confirmed.
[0020]
Example 2
Under a nitrogen atmosphere, 29 mmol of NBL was added to 2000 g of THF, and a mixture of 1 mol of PTBST and 0.3 mol of styrene was added dropwise over 1 hour while maintaining at −50 ° C. with stirring, and the reaction was continued for another 1 hour. The completion of the reaction was confirmed by GC. The PTBST / styrene polymer at this stage was a monodisperse polymer with Mn = 11000 and Mw / Mn = 1.05. Next, 150 mmol of lithium chloride was added to the reaction system, 0.3 mol of tert-butyl acrylate [hereinafter abbreviated as “t-BA”] was added dropwise over 1 hour, and the reaction was further continued for 1 hour. It was confirmed that the reaction was complete. Next, methanol is added to the reaction system to stop the reaction, the reaction solution is poured into a large amount of methanol to precipitate a polymer, filtered, washed, and dried under reduced pressure at 60 ° C. for 15 hours to form a white powder. A polymer was obtained. The polymerization yield based on the total amount of monomers used was 99.3%. When GPC analysis of this polymer was conducted, it was a monodisperse polymer with Mn = 1530, Mw / Mn = 1.13.
[0021]
Next, 10 g of the obtained polymer was dissolved in propylene glycol monoethyl ether to form a 25% solution, and 0.2 g of potassium hydrogen sulfate was added to react at 90 ° C. The reaction progress was followed in the same manner as in Example 1, and reached the end point after 5 hours. The reaction solution was filtered to remove potassium hydrogen sulfate, and then the solvent was removed from the filtrate under reduced pressure to obtain 7.5 g of a white powdery polymer. In this reaction, the NMR of the polymer before and after the reaction was measured. As in Example 1, the disappearance of the peak derived from the t-butoxy group of polyPTBST and the peak derived from the t-butyl group of polyt-BA It was confirmed that there was no change and that no new peak derived from the carboxyl group appeared. Moreover, as a result of measuring GPC about the produced | generated polymer, it is a monodispersed polymer of Mn = 9520 and Mw / Mn = 1.13, and the copolymerization ratio measured by NMR is p-hydroxystyrene unit / styrene unit / t-. The BA unit was 1 / 0.3 / 0.3 (molar ratio).
From the above, the copolymerization reaction and the selective elimination reaction were performed as set up, and an alkenylphenol-based partial block copolymer composed of a p-hydroxystyrene segment, a styrene segment, and a t-BA segment was produced. It was confirmed.
[0022]
Example 3
Under a nitrogen atmosphere, 280 g of propylene glycol monoethyl ether was added with 0.71 mol of PTBST, 0.11 mol of t-BA, 0.05 mol of azobisisobutyronitrile, and 0.007 mol of 1-dodecanethiol. With stirring, the reaction was carried out at 70 ° C. for 5 hours and further at 85 ° C. for 5 hours. Next, after adding the same amount of hexane, double amount of methanol and a small amount of water to the reaction solution and removing the unreacted monomer by liquid separation purification, the solvent component is distilled off under reduced pressure from the polymer layer to obtain a lighter solution. A brown powdery polymer was obtained. The yield based on the total amount of monomers used was 88.6%. When GPC analysis of this polymer was performed, it was a unimodal polymer with Mn = 8500 and Mw / Mn = 1.45.
[0023]
Next, 10 g of the obtained polymer was dissolved in propylene glycol monoethyl ether to form a 20% solution, and 0.1 g of potassium hydrogen sulfate was added to react at 100 ° C. The reaction progress was traced in the same manner as in Example 1, and reached the end point after 4 hours. The reaction solution is filtered to remove potassium hydrogen sulfate, and then poured into a large amount of water to precipitate a polymer. After filtration, washing and drying under reduced pressure at 80 ° C. for 15 hours, 6.3 g of a light brown powdery polymer Got. In this reaction, when the IR and NMR of the polymer before and after the reaction were measured, as in Example 1, the disappearance of the peak derived from the t-butoxy group of polyPTBST and the peak derived from the t-butyl group of polyt-BA It was confirmed that there was no change at all, and that no new peak derived from the carboxyl group appeared. Moreover, as a result of measuring GPC about the produced | generated polymer, it is a monomodal polymer of Mn = 6060 and Mw / Mn = 1.46, The copolymerization ratio measured by NMR is p-hydroxy styrene unit / t-BA unit. = 1 / 0.15 (molar ratio).
From the above, it was confirmed that the copolymerization reaction and the selective elimination reaction were carried out as set up, and an alkenylphenol random copolymer composed of a p-hydroxystyrene segment and a t-BA segment was produced. .
[0024]
Comparative Example 1
10 g of the copolymer of PTBST and t-BMA obtained in Example 1 was dissolved in a toluene / ethanol = 1/1 (weight ratio) mixed solvent to obtain a 25% solution, and 1 g of 35% concentrated hydrochloric acid was added to obtain 65%. The reaction was performed at 0 ° C. The progress of the reaction was followed in the same manner as in Example 1, and reached the end point after 7 hours. The reaction solution was washed with water to remove concentrated hydrochloric acid, and poured into a large amount of water to precipitate a polymer. After filtration and washing, vacuum drying was performed at 65 ° C. for 15 hours to obtain 6.2 g of a white powdery polymer. As a result of analyzing the obtained polymer by NMR, the disappearance of the peak derived from the t-butoxy group of polyPTBST was confirmed, but the area ratio of the t-butyl group of t-BMA to the benzene ring carbon was decreased, In addition, a broad peak derived from a carboxyl group appeared at 177 to 178 ppm. From this, it was confirmed that a part of t-BMA segment hydrolyzed and the methacrylic acid segment produced | generated.
[0025]
Comparative Example 2
10 g of the copolymer of PTBST and t-BA obtained in Example 3 was dissolved in propylene glycol monoethyl ether to form a 20% solution, and 0.01 g of concentrated sulfuric acid was added and the reaction was performed at 75 ° C. The reaction progress was followed in the same manner as in Example 1, and reached the end point after 5 hours. The reaction solution was washed with water to remove concentrated sulfuric acid, and poured into a large amount of water to precipitate a polymer. After filtration and washing, vacuum drying was performed at 65 ° C. for 15 hours to obtain 5.7 g of a light brown powdery polymer. As a result of analyzing the obtained polymer by NMR, the disappearance of the peak derived from the t-butoxy group of polyPTBST was confirmed, but the area ratio of the t-butyl group of t-BA to the benzene ring carbon was decreased, In addition, a broad peak derived from a carboxyl group appeared at 177 to 178 ppm. From this, it was confirmed that a part of the t-BA segment was hydrolyzed to produce an acrylic acid segment.
[0026]
【The invention's effect】
According to the present invention, a compound in which the hydroxyl group of the phenol residue of alkenylphenol is protected by a saturated aliphatic protecting group, a (meth) acrylic acid ester, and a vinyl aromatic compound used as necessary are copolymerized. Only the saturated aliphatic protective group can be selectively removed from the copolymer obtained in this manner, and the (meth) acrylic acid skeleton, that is, a copolymer having a carboxyl group, cannot be put to practical use as an ESCAP type resist. An alkenylphenol copolymer useful for an ESCAP resist can be produced without the production of a polymer.

Claims (7)

The following general formula (I)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 6 carbon atoms). The hydroxyl group of the phenol residue represented by this is protected by a saturated aliphatic protecting group. In the method for obtaining an alkenylphenol copolymer by removing a saturated aliphatic protecting group from a copolymer obtained by copolymerizing a compound and an acrylate ester or a methacrylate ester, Formula (II)
XHSO ₄ (II)
(In the formula, X represents an alkali metal) A bisulfate represented by the formula is used. The following general formula (I)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 6 carbon atoms). The hydroxyl group of the phenol residue represented by this is protected by a saturated aliphatic protecting group. In a method of obtaining an alkenylphenol copolymer by removing a saturated aliphatic protecting group from a copolymer obtained by copolymerizing a compound, a vinyl aromatic compound, and an acrylic ester or a methacrylic ester. As a desorbing agent, the following general formula (II)
XHSO ₄ (II)
(In the formula, X represents an alkali metal) A bisulfate represented by the formula is used. The method for producing an alkenylphenol copolymer according to claim 1 or 2, wherein the acrylic ester is t-butyl acrylate and the methacrylic ester is t-butyl methacrylate. The method for producing an alkenylphenol copolymer according to any one of claims 1 to 3, wherein the copolymer is a random copolymer. The method for producing an alkenylphenol copolymer according to any one of claims 1 to 3, wherein the copolymer is a block copolymer. X in the general formula (II) XHSO ₄ is lithium, potassium method for producing alkenyl phenols copolymer according to any one of claims 1 to 5, wherein the, or any of sodium. The addition amount of the bisulfate represented by the general formula (II) is 0.1 to 100 parts by weight with respect to 100 parts by weight of the copolymer. A method for producing an alkenylphenol copolymer.