JP4117945B2

JP4117945B2 - Improved hydrogenation method of conjugated diene polymer

Info

Publication number: JP4117945B2
Application number: JP26829798A
Authority: JP
Inventors: 茂佐々木; 昌水釜谷; 裕司新庄
Original assignee: Asahi Kasei Chemicals Corp
Current assignee: Asahi Kasei Chemicals Corp
Priority date: 1998-09-22
Filing date: 1998-09-22
Publication date: 2008-07-16
Anticipated expiration: 2018-09-22
Also published as: JP2000095814A

Description

【０００１】
【発明の属する技術分野】
本発明は、有機アルカリ金属化合物を重合開始剤として重合した共役ジエン系重合体を、メタロセン系水素添加触媒を用いて、水素と接触させて共役ジエンの二重結合を水素添加する方法に関する。更には、その際、工業的に１ｍ³以上の大きな反応容器を用いて、水素添加率９８％以上の共役ジエン系重合体を得る際、水素添加触媒を数次に分けて添加する事により、安定に、また短時間で経済的に水素添加する方法に関する。
【０００２】
【従来の技術】
メタロセン系触媒は、重合物の水素添加（以下水添と略す）に用いる場合、ニッケル系触媒に比べれば、よりマイルドな条件下で、より少ない量で同量の水添を成し遂げるという特徴が有り、この為、水添後、触媒残差を取り除く特別な処理が必要なく、又、たとえ行う場合も触媒残差を取り除く処理が軽くて済むという特徴が有るため、近年、よく使われるようになってきた。しかしメタロセン系触媒は、価格が高く、また容易に活性を失い易いという問題を有するため、従来、より高活性で、取扱い方が易しく長期貯蔵安定性の良い水添触媒が種々検討され提案されてきた。例えば、特定のチタノセン化合物とアルキルリチウムを組み合わせて、オレフィン化合物を水添する方法（特開昭６１−３３１３２号、特開平１−５３８５１号）、メタロセン化合物と有機アルミニウム、亜鉛、マグネシウムと組み合わせでオレフィン性不飽和（共）重合物を水添する方法（特開昭６１−２８５０７号、６２−２０９１０３号）、特定のチタノセン化合物とアルキルリチウムとの組合せでオレフィン性不飽和基含有リビングポリマーを水添させる方法（特開昭６１−４７７０６号、特開昭６３−５４０２号）、チタノセン化合物とトリメチルアルミニウムのメタラサイクル化合物であるＴｅｂｂｅ試薬とアルキルアルカリ金属化合物を組み合わせた反応物によるオレフィン性不飽和二重結合含有ポリマー中のオレフィン性二重結合を水添する方法（米国特許５２４４９８０号）、チタノセン化合物を、特定された量のリチウムアルコキサイトと組み合わせオレフィン性不飽和二重結合含有ポリマー中のオレフィン性二重結合を水添する方法（特開平１−２７５６０５）、メタロセン系水添触媒を用い、特定比率で有機アルミニウム化合物その他を存在させた系で共役ジエン重合物を水添する方法（特願平９−２５２１８０）等の方法が提案されている。
【０００３】
【本発明が解決しようとする課題】
しかしながら、この様ないずれの方法においても、実際に工業的に１ｍ³以上の大きな反応容器内で、９８％以上の高水添率の共役ジエン系重合体を得ようとすると、温度変化などで水添条件が変動したり、触媒使用量を経済性追求のため減らしたりすると、水添時間が長くかかったり、はなはだしくは目的の高水添率の重合体が得られないなどのトラブルが生じた。この為、なるべく少ない触媒使用量で、工業的に短時間で安定に高水添を達成する為の水添方法の改良が望まれていた。
【０００４】
【課題を解決するための手段】
本発明者らは従来技術の上記の問題点を解決すべく鋭意検討した結果、このような１ｍ³以上の大きな反応容器内で水添を行う場合、水添触媒を数次に分けて添加する事、好ましくは特に特定の水添率で必ず１回以上触媒を追添する事により、工業的に安定に短時間で経済的に、高水添率の水添を達成する方法を見つけ出し、本発明を成すに至った。
【０００５】
本発明は、１ｍ³以上、好ましくは５ｍ³以上、さらに好ましくは１０ｍ³以上の大きな反応容器を用いて工業的に、有機アルカリ金属化合物を重合開始剤として重合した共役ジエン系重合体をメタロセン系水添触媒を用いて水添し、水添率９８％以上の共役ジエン系重合体を得る際、水添触媒を２回以上、好ましくは２〜１０回に分けて添加し水添を進める事、更に好ましくは、重合体の水添率が６０％〜９５％の時点で、１回以上水添触媒を追添する事を特徴とする改良された共役ジエン系重合体の水添方法である。
【０００６】
本発明で重合開始剤として用いられる有機アルカリ金属化合物は、一般的に共役ジエン化合物に対しアニオン重合活性があることが知られている脂肪族炭化水素アルカリ金属化合物、芳香族炭化水素アルカリ金属化合物、有機アミノアルカリ金属化合物等が含まれ、アルカリ金属としてはリチウム、ナトリウム、カリウム等である。好適な有機アルカリ金属化合物としては、炭素数１から２０の脂肪族および芳香族炭化水素リチウム化合物であり、１分子中に１個のリチウムを含む化合物、１分子中に複数のリチウムを含むジリチウム化合物、トリリチウム化合物、テトラリチウム化合物が含まれる。具体的にはｎ−プロピルリチウム、ｎ−ブチルリチウム、ｓｅｃ−ブチルリチウム、ｔｅｒｔ−ブチルリチウム、ｎ−ペンチルリチウム、ｎ−ヘキシルリチウム、ベンジルリチウム、フェニルリチウム、トリルリチウム、ジイソプロペニルベンゼンとｓｅｃ−ブチルリチウムの反応生成物、さらにジビニルベンゼンとｓｅｃ−ブチルリチウムと少量の１，３−ブタジエンの反応生成物等があげられる。
【０００７】
本発明の共役ジエン系重合体は、共役ジエンのホモ重合体、２種以上の共役ジエンからなる共役ジエンの共重合体、また共役ジエンと共重合可能な他の単量体との共重合体であって、該重合体中に共役ジエンから由来するオレフィン２重結合を有する１，４−重合体、１，２または３，４−重合体を含むものである。共役ジエンとしては、炭素数４から２０の炭素原子を有する共役ジエン、具体的には１，３−ブタジエン、イソプレン、２，３−ジメチル−１，３−ブタジエン、１，３−ペンタジエン、２−メチル−１，３−ペンタジエン、１，３−ヘキサジエン、４，５−ジエチル−１，３−オクタジエン、３−ブチル−１，３−オクタジエン等が挙げられる。工業的に有利に展開でき、物性の優れた弾性体を得る上からは、１，３−ブタジエン、イソプレンが好ましい。また、共役ジエンと共重合可能な他の単量体として代表的なものはビニル芳香族化合物である。例えばスチレン、α−メチルスチレン、ｐ−メチルスチレン、ジビニルベンゼン、１，１−ジフェニルエチレン、Ｎ，Ｎ−ジメチル−ｐ−アミノエチルスチレン、Ｎ，Ｎ−ジエチル−ｐ−アミノエチルスチレン等があげられ、好ましくはスチレン、α−メチルスチレンである。これらの共重合体はランダム、またはブロック共重合体である。
【０００８】
水添は通常不活性炭化水素溶媒中で行われるが、この不活性炭化水素溶媒としては、共役ジエン系重合体の溶媒であって水素添加の際に反応に悪影響を与えないものである。本発明ではさらに、重合に引き続いて同じ不活性炭化水素溶媒中で水素添加が行われることが好ましい。好適な溶媒は、例えばｎ−ブタン、イソブタン、ｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、ｎ−オクタンの如き脂肪族炭化水素類、シクロヘキサン、シクロヘプタン、メチルシクロヘプタンの如き脂環式炭化水素類、また、ベンゼン、トルエン、キシレン、エチルベンゼンの如き芳香族炭化水素も、選択された水添条件下で芳香族二重結合が水添されない時に限って使用することができる。この溶媒中に溶かす共役ジエン系重合体の濃度は、５〜４０％、好ましくは１０〜３０％の濃度にする。この濃度が５％より低いと、共役ジエン系重合体と溶媒を分離する後工程の負荷が大きくなり好ましくなく、４０％を越える濃度であると粘度がはなはだしく高くなり、水素、水添触媒などとの混合性や伝熱性が低下し、ひいては水添反応に影響するため好ましくない。
【０００９】
本発明で用いられるメタロセン系水添触媒は、配位子として同一又は異なる２個の（置換）シクロペンタジエニル基を持つチタン、ジルコニウム、ハフニウム等の有機金属化合物であり、好ましくは還元性の有機金属化合物、例えばアルキルリチウム、アルキルマグネシウム、アルキルアルミニウム、アルキル亜鉛等と用いられる。水添方法としては、メタロセン系化合物を用いる水添方法であればどの方法も採用できる。例えば、特定のチタノセン化合物とアルキルリチウムを組み合わせて、オレフィン化合物を水添する方法（特開昭６１−３３１３２号、特開平１−５３８５１号）、メタロセン化合物と有機アルミニウム、亜鉛、マグネシウムと組み合わせでオレフィン性不飽和（共）重合物を水添する方法（特開昭６１−２８５０７号、６２−２０９１０３号）、特定のチタノセン化合物とアルキルリチウムとの組合せでオレフィン性不飽和基含有リビングポリマーを水添させる方法（特開昭６１−４７７０６号、特開昭６３−５４０２号）、チタノセン化合物とトリメチルアルミニウムのメタラサイクル化合物であるＴｅｂｂｅ試薬とアルキルアルカリ金属化合物を組み合わせた反応物によるオレフィン性不飽和二重結合含有ポリマー中のオレフィン性二重結合を水添する方法（米国特許５２４４９８０号）、チタノセン化合物を、特定された量のリチウムアルコキサイトと組み合わせオレフィン性不飽和二重結合含有ポリマー中のオレフィン性二重結合を水添する方法（特開平１−２７５６０５）、メタロセン系水添触媒を用い、特定比率で有機アルミニウム化合物その他を存在させた系で共役ジエン重合物を水添する方法（特願平９−２５２１８０）等の何れの方法でも良い。また水添条件も、この様な水添触媒に合わせた、各明細書に書かれた方法を用いる事ができる。
【００１０】
このような水添触媒を、当初の１回を含めて２回以上、好ましくは２〜１０回に分け、更に好ましくは２〜５回に分けて添加する。この場合、最低２回に分け、好ましくは、重合体の水添率が６０％〜９５％の時点で、更に好ましくは７０％〜９５％の時点で、少なくとも１回以上水添触媒を追添する事がきわめて重要である。すなわちメタロセン系水添触媒を用いて１ｍ³以上の工業的な反応容器内で水添を行うと、重合体ポリマー溶液の水添率が６０％〜９５％と上昇すると粘度も大幅に上昇し、除熱能力が悪化し、局部的な温度上昇が発生し易くなる。特に水添反応は激しい発熱反応であり、この傾向は著しい。局部的な温度上昇が発生すると、その部分の水添反応はますます活性化し、更なる発熱を引き起こし、最後には水添触媒の活性が喪失する触媒の失活反応を引き起こす。このため、結果的に水添反応の低下や甚だしくは目的の高水添率の重合体が得られないなどのトラブルが起こり易い。この現象は大型の反応器ほど顕著であり、工業的な生産をおこなう際の大きな課題である。しかし、このような水添率に達した時点で触媒を追添する事で、必要な時点で必要な量の活性触媒を供給でき、多段に追添することで、全触媒使用量としてはむしろ少なくても、短時間で確実で安定に９８％以上という高水添率の重合体を得るまで水添する事が可能となる。水添触媒は、最初の１回目の添加分は重合体と触れた後で活性化しても良いが、少なくとも追添触媒は、水添活性を発現した後か水素雰囲気で直ちに活性化する状態で添加する事が好ましい。数次添加の水添触媒は、初回添加分と後添加の触媒は同じ物でなくてもかまわないが、同じ物の方が、運転の簡便性から望ましい。更に１１回以上に分けて添加する事は、操作が煩雑になり好ましくなく、２〜１０回、望ましくは２〜５回、更に望ましくは２〜３回に分けていれる事は、操作性と触媒効率や水添確実性を両立でき好ましい。触媒追添時期である、重合体の水添率が６０％〜９５％の時点、更に好ましくは７０％〜９５％の時点を判別する方法としては、水添された共役ジエン系重合体の二重結合の残存量の測定、使用された水素ガス量からの算出、水添容器内の水素圧力変化、水添時間など何れの指標を基に判別しても良い。更に重合体の水添率が６０％〜９５％の時点、更に好ましくは７０％〜９５％の時点まで、特定の容器内でバッチ式又は連続及び又は回分式に水添を行い、水添触媒を追添し別の容器や配管内で９８％まで残りの部分の水添を行ってもよい。いずれにしても、このように分割して水添触媒を添加する事により効率的でしかも安定で確実に工業的に水添を行う事ができる。なお本発明における水添率は、重合体中に含まれる共役ジエン単位の水添率を意味する。
【００１１】
【実施例】
以下の実施例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。実施例に用いた各リビングポリマー（Ａポリマー及びＢポリマー）の合成例を以下の製造例に示した。
【００１２】
製造例１
１６ｍ³の撹拌機付き反応器中にシクロヘキサン４．３トン、スチレンモノマー０．２０トンを入れた後、１５％ｎ−ブチルリチウム溶液４．８ｋｇ、更にテトラメチルエチレンジアミン０．６２ｋｇを加え、初期温度を７０℃に設定し撹拌下で４０分間重合した。次いで、１，３ブタジエンモノマーを３０％含むシクロヘキサン溶液を３．０８トン追加し１時間重合した。更にスチレンモノマーを３０％含むシクロヘキサン溶液を０．６６トン追加し４０分間重合した。重合時のピーク温度は８２℃であった。得られたリビングポリマー（Ａポリマー）は、結合スチレン含有量３０％、ブロックスチレン含有量３０％、ブタジエン単位の１，２−ビニル結合含有量３７％であり、数平均分子量が約２３万であるスチレン−ブタジエン−スチレン型リビングブロックポリマーであった。
【００１３】
製造例２
１６ｍ³の撹拌機付き反応器中にシクロヘキサン４．８５トン、スチレンモノマー０．３３トンを入れた後、１５％ｎ−ブチルリチウム溶液２２ｋｇを加え、更にテトラメチルエチレンジアミン１．７ｋｇを加え、初期温度を７０℃に設定し撹拌下で３０分重合した。次いで、１，３ブタジエンモノマーを３０％含むシクロヘキサン溶液を５．１８トン追加し４５分間重合した。更にスチレンモノマーを３０％含むシクロヘキサン溶液を１．１１トン追加し３０分間重合した。重合時のピーク温度は、８５℃であった。得られたリビングポリマー（Ｂポリマー）は、結合スチレン含有量３０％、ブロックスチレン含有量３０％、ブタジエン単位の１，２−ビニル結合含有量３９％である数平均分子量が約６．１万のスチレン−ブタジエン−スチレン型リビングブロックポリマーであった。
【００１４】
実施例１
特開平８−３３８４６の方法に準拠した方法により水添触媒調製を行った。すなわち、ビス（シクロペンタジエニル）チタニウムジ−ｐ−トリル（ＴＰＭ）６ｋｇをシクロヘキサン５２６ｋｇ中に溶解し、液状１，２ポリブタジエン６０ｋｇを添加した後、１５％ブチルリチウム溶液を７．１ｋｇ添加、更にはエタノール０．６ｋｇを添加し反応させ、水添触媒（ＴＰＭ／Ｌｉ）として調製した。一方、水添の前処理として、製造例１で得られたリビングポリマー（Ａポリマー）溶液に、精製乾燥したシクロヘキサンを加えて１１％のポリマー濃度のシクロヘキサン溶液に調整し、更に重合触媒であるｎ−ブチルリチウムの０．８等量モル分エチルアルコールを加えた。このポリマー溶液を２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。ここに、先ほど調製した水添触媒（ＴＰＭ／Ｌｉ）を、Ｔｉ重量基準でポリマー重量に対し２０ｐｐｍ添加し水添を開始した。２３分後、水素ガスの消費量からみたポリマーの水添率が７０％となり、この時点で、更に、水添触媒（ＴＰＭ／Ｌｉ）をＴｉ重量基準で２０ｐｐｍ追加し、水添を継続した。３５分後、水素ガスの消費量からみたポリマーの水添率が１００％となり、水素のポリマー溶液への吸収も停止したので水添を終了し、ＮＭＲ法によりポリマーの水添率を測定したところ９９．９％であった。なお水添中の最高到達温度は９５℃であった。
【００１５】
比較例１
製造例１と同様の方法で得られたリビングポリマー（Ａポリマー）溶液を、実施例１と同様の方法で前処理した後、２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、０．７ＭＰａの水素ガス加圧下とした。これに、Ｔｉ重量基準でポリマー重量に対し４０ｐｐｍとなるように実施例１と同様の方法で調製した水添触媒（ＴＰＭ／Ｌｉ）を添加し、水添を開始した。６５分後、水素ガスの消費量からみたポリマーの水添率は９７％で有ったが、水素のポリマー溶液への吸収がほぼ停止していたため、水添を終了した。ＮＭＲ法による最終ポリマーの水添率は９６．８％であった。なお水添中の最高到達温度は１００℃であった。
【００１６】
実施例２
前処理として、製造例２で得られたリビングポリマー（Ｂポリマー）に、精製乾燥したシクロヘキサンを加えて１９％のポリマー濃度のシクロヘキサン溶液に調整した後、エチルアルコールをｎ−ブチルリチウムの０．９等量モル分加えた。次いでこのポリマー溶液を２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。Ｔｉ重量基準でポリマー重量に対し１０ｐｐｍとなるように、実施例１と同様の方法で調製された水添触媒（ＴＰＭ／Ｌｉ）を反応容器内に添加し、水添を開始した。３５分後、水素ガスの消費量からみたポリマーの水添率が６１％となり、この時点で、Ｔｉ重量基準で５ｐｐｍとなる量の水添触媒（ＴＰＭ／Ｌｉ）を追加し、水添を継続した。４０分後、水素ガスの消費量からみたポリマーの水添率が８５％の時点で更にＴｉ重量基準で５ｐｐｍ追加し、水添を継続した。４５分後、水素ガスの消費量からみたポリマーの水添率が１００％となり、水素のポリマー溶液への吸収も停止したので水添を終了し、ＮＭＲ法によりポリマーの水添率を測定したところ９９．８％であった。なお水添中の最高到達温度は９０℃であった。
【００１７】
比較例２
製造例２と同様の方法で得られたリビングポリマー（Ｂポリマー）溶液を、実施例２と同様の方法で前処理した後、２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。更に、実施例１と同様の方法で調製された水添触媒（ＴＰＭ／Ｌｉ）をＴｉ重量基準でポリマー重量に対し２０ｐｐｍ添加し、水添を開始した。１０５分後、水素ガスの消費量からみたポリマーの水添率は８５％で有ったが、水素のポリマー溶液への吸収がほぼ停止していたため、水添を終了し、ＮＭＲ法による最終ポリマーの水添率を測定したところ、水添率は８５．１％であった。なお水添中の最高到達温度は９５℃であった。
【００１８】
実施例３
特願平９−２５２１８０の方法に準拠した方法により水添触媒調製を行った。ビス（シクロペンタジエニル）チタニウムジクロライド５ｋｇをシクロヘキサン７０．１ｋｇに添加し、撹拌後、１０％トリメチルアルミニウム溶液２４．９ｋｇを追加し７２時間反応させ、水添触媒（ＴＣ／ＴＭＡＬ）溶液として調製した。一方、製造例１で得られたと同様のリビングポリマー（Ａポリマー）溶液を、実施例１と同様の方法で前処理した後、２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。ここに、先ほど調製した水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で、ポリマー重量に対し３０ｐｐｍ添加し水添を開始した。２０分後、水素ガスの消費量からみたポリマーの水添率が６５％となり、この時点で、水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で更に２０ｐｐｍ追加し、水添を継続した。２３分後、水素ガスの消費量からみたポリマーの水添率が８０％となった時点で、水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で更に１０ｐｐｍ追加し、水添を継続した。更に、水添開始から２７分後、水素ガスの消費量からみたポリマーの水添率が９０％となった時点で、水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で更に１０ｐｐｍ追加し、水添を継続した。３０分後、水素ガスの消費量からみたポリマーの水添率が１００％となり、水素のポリマー溶液への吸収も停止したので水添を終了し、ＮＭＲ法によりポリマーの水添率を測定したところ１００％であった。なお水添中の最高到達温度は９８℃であった。
【００１９】
比較例３
製造例１と同様の方法で得られたリビングポリマー（Ａポリマー）溶液を、実施例１と同様の方法で前処理した後、２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。更に実施例３と同様の方法で調製された水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で、ポリマー重量に対し７０ｐｐｍ添加し水添を開始した。３０分後の水素ガスの消費量からみたポリマーの水添率は９１％で有り、水素のポリマー溶液への吸収もほぼ停止しており、ＮＭＲ法によるポリマーの水添率は９１．０％であった。なお水添中の最高到達温度は１０２℃であった。
【００２０】
実施例４
製造例２と同様の方法で得られたリビングポリマー（Ｂポリマー）溶液を、実施例２と同様の方法で前処理した後、２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。更に実施例３と同様の方法で調製された水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で、ポリマー重量に対し１５ｐｐｍ添加し水添を開始した。２５分後、水素ガスの消費量からみたポリマーの水添率が７５％となり、この時点で、水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で更に５ｐｐｍ追加し、水添を継続した。２９分後、水素ガスの消費量からみたポリマーの水添率が８８％の時点で水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で更に５ｐｐｍ追加し、水添を継続した。更に水添開始から３２分後、水素ガスの消費量からみたポリマーの水添率が９３％の時点で水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で更に５ｐｐｍ追加し、水添を継続した。３５分後、水素ガスの消費量からみたポリマーの水添率が１００％となり、水素のポリマー溶液への吸収も停止したので水添を終了し、ＮＭＲ法によりポリマーの水添率を測定したところ９９．９％であった。なお水添中の最高到達温度は８９℃であった。
【００２１】
比較例４
製造例２と同様の方法で得られたリビングポリマー（Ｂポリマー）溶液を、実施例２と同様の方法で前処理した後、２０ｍ³の撹拌機付き反応器に全量移送した。撹拌下で反応器内を初期温度８０℃に設定した後、反応器内を水素ガスで置換し、更に０．７ＭＰａの水素ガス加圧下とした。更に実施例３と同様の方法で調製された水添触媒（ＴＣ／ＴＭＡＬ）をＴｉ重量基準で、ポリマー重量に対し３０ｐｐｍ添加し水添を開始した。７０分後、水素ガスの消費量からみたポリマーの水添率は８９％で有り、水素のポリマー溶液への吸収もほぼ停止した。この時点でのＮＭＲ法によるポリマーの水添率は８９．２％であった。なお水添中の最高到達温度は９８℃であった。
【００２２】
以上の実施例１〜４、比較例１〜４の水添条件と結果を纏めたのが、表１で有る。
【００２３】
【表１】

【００２４】
【発明の効果】
本発明は、１ｍ³以上の大きな反応容器を用いて工業的に、水添率９８％以上の共役ジエン系重合体を得る為、メタロセン系水添触媒を用いて水添する際、水添触媒を数次に分けて添加する事で、少ない水添触媒量で安定に短時間で確実に水添できる工業的に極めて有利な方法を提供するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method in which a conjugated diene polymer obtained by polymerizing an organic alkali metal compound as a polymerization initiator is brought into contact with hydrogen using a metallocene hydrogenation catalyst to hydrogenate a conjugated diene double bond. Furthermore, at that time, when a conjugated diene polymer having a hydrogenation rate of 98% or more is obtained using a large reaction vessel of 1 m ³ or more industrially, a hydrogenation catalyst is added in several orders, The present invention relates to a method for hydrogenation stably and in a short time economically.
[0002]
[Prior art]
When used for hydrogenation of polymers (hereinafter abbreviated as hydrogenation), metallocene-based catalysts have the characteristic of achieving the same amount of hydrogenation in smaller amounts under milder conditions than nickel-based catalysts. For this reason, after hydrogenation, there is no need for a special process for removing the catalyst residual, and even if it is carried out, the process for removing the catalyst residual is lighter. I came. However, since metallocene-based catalysts have problems that they are expensive and easily lose their activity, various hydrogenation catalysts having higher activity, easier handling, and long-term storage stability have been studied and proposed. It was. For example, a method of hydrogenating an olefin compound by combining a specific titanocene compound and alkyllithium (JP-A 61-33132, JP-A-1-53851), an olefin in combination with a metallocene compound, organoaluminum, zinc and magnesium. Hydrogenating an unsaturated unsaturated (co) polymer (Japanese Patent Laid-Open Nos. 61-28507 and 62-209103), hydrogenating a living polymer containing an olefinically unsaturated group by a combination of a specific titanocene compound and an alkyl lithium Olefinic unsaturated double reaction by a reaction product of a combination of a Tebbe reagent, which is a metallacycle compound of a titanocene compound and trimethylaluminum, and an alkyl alkali metal compound (JP-A-61-47706, JP-A-63-5402) Olefinic polymers in bond-containing polymers A method of hydrogenating a bond (US Pat. No. 5,244,980), a method in which a titanocene compound is combined with a specified amount of lithium alkoxide to hydrogenate an olefinic double bond in an olefinically unsaturated double bond-containing polymer ( JP-A-1-275605), a method of hydrogenating a conjugated diene polymer in a system in which an organoaluminum compound or the like is present in a specific ratio using a metallocene hydrogenation catalyst (Japanese Patent Application No. 9-252180) is proposed. Has been.
[0003]
[Problems to be solved by the present invention]
However, in any of these methods, in order to obtain a conjugated diene polymer having a high hydrogenation rate of 98% or more in an industrially large reaction vessel of 1 m ³ or more, hydrogenation due to temperature change or the like. If the conditions were changed or the amount of catalyst used was reduced in order to pursue economic efficiency, troubles such as a long hydrogenation time or a failure to obtain the desired high hydrogenation rate polymer occurred. For this reason, improvement of the hydrogenation method for achieving high hydrogenation stably industrially in a short time with the usage-amount of a catalyst as small as possible was desired.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors add hydrogenation catalyst in several orders when hydrogenation is performed in such a large reaction vessel of 1 m ³ or more. In particular, a method for achieving hydrogenation at a high hydrogenation rate in an industrially stable manner in a short time by finding out a method of adding the catalyst at least once at a specific hydrogenation rate and finding a method for achieving the high hydrogenation rate has been found. It came to be accomplished.
[0005]
In the present invention, a conjugated diene polymer obtained by polymerizing an organic alkali metal compound as a polymerization initiator industrially using a large reaction vessel of 1 m ³ or more, preferably 5 m ³ or more, more preferably 10 m ³ or more is used as a metallocene-based polymer. When hydrogenation is performed using a hydrogenation catalyst to obtain a conjugated diene polymer having a hydrogenation rate of 98% or more, the hydrogenation catalyst is added twice or more, preferably 2 to 10 times, and the hydrogenation proceeds. More preferably, the improved hydrogenation method of the conjugated diene polymer is characterized in that when the hydrogenation rate of the polymer is 60% to 95%, the hydrogenation catalyst is added once or more. .
[0006]
The organic alkali metal compound used as a polymerization initiator in the present invention is generally an aliphatic hydrocarbon alkali metal compound, an aromatic hydrocarbon alkali metal compound known to have anionic polymerization activity with respect to a conjugated diene compound, Organic amino alkali metal compounds and the like are included, and alkali metals include lithium, sodium, potassium, and the like. Suitable organic alkali metal compounds are aliphatic and aromatic hydrocarbon lithium compounds having 1 to 20 carbon atoms, a compound containing one lithium in one molecule, and a dilithium compound containing a plurality of lithiums in one molecule , Trilithium compounds, and tetralithium compounds. Specifically, n-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-pentyllithium, n-hexyllithium, benzyllithium, phenyllithium, tolyllithium, diisopropenylbenzene and sec- A reaction product of butyllithium, a reaction product of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene can be used.
[0007]
The conjugated diene polymer of the present invention is a homopolymer of a conjugated diene, a copolymer of a conjugated diene composed of two or more conjugated dienes, or a copolymer with other monomers copolymerizable with the conjugated diene. The polymer contains a 1,4-polymer, 1,2, or 3,4-polymer having an olefinic double bond derived from a conjugated diene. Conjugated dienes include conjugated dienes having 4 to 20 carbon atoms, specifically 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2- Examples include methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, and 3-butyl-1,3-octadiene. From the viewpoint of obtaining an elastic body that can be industrially advantageously developed and has excellent physical properties, 1,3-butadiene and isoprene are preferred. A representative example of the other monomer copolymerizable with the conjugated diene is a vinyl aromatic compound. Examples thereof include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and the like. Styrene and α-methylstyrene are preferable. These copolymers are random or block copolymers.
[0008]
Hydrogenation is usually carried out in an inert hydrocarbon solvent. This inert hydrocarbon solvent is a conjugated diene polymer solvent that does not adversely affect the reaction during hydrogenation. In the present invention, it is further preferable that hydrogenation is carried out in the same inert hydrocarbon solvent following the polymerization. Suitable solvents are aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, n-octane, and alicyclic hydrocarbons such as cyclohexane, cycloheptane, methylcycloheptane. Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene can also be used only when the aromatic double bond is not hydrogenated under the selected hydrogenation conditions. The concentration of the conjugated diene polymer dissolved in the solvent is 5 to 40%, preferably 10 to 30%. If this concentration is lower than 5%, the load of the post-process for separating the conjugated diene polymer and the solvent is undesirably increased. If the concentration exceeds 40%, the viscosity is remarkably increased, and hydrogen, hydrogenation catalyst, etc. This is not preferable because the mixing property and heat transfer property of the resin are reduced, which in turn affects the hydrogenation reaction.
[0009]
The metallocene hydrogenation catalyst used in the present invention is an organometallic compound such as titanium, zirconium or hafnium having two (substituted) cyclopentadienyl groups which are the same or different as a ligand, preferably a reductive compound. Organometallic compounds such as alkyl lithium, alkyl magnesium, alkyl aluminum, alkyl zinc and the like are used. As a hydrogenation method, any method can be adopted as long as it is a hydrogenation method using a metallocene compound. For example, a method of hydrogenating an olefin compound by combining a specific titanocene compound and alkyllithium (JP-A 61-33132, JP-A-1-53851), an olefin in combination with a metallocene compound, organoaluminum, zinc and magnesium. Hydrogenating an unsaturated unsaturated (co) polymer (Japanese Patent Laid-Open Nos. 61-28507 and 62-209103), hydrogenating a living polymer containing an olefinically unsaturated group by a combination of a specific titanocene compound and an alkyl lithium Olefinic unsaturated double reaction by a reaction product of a combination of a Tebbe reagent, which is a metallacycle compound of a titanocene compound and trimethylaluminum, and an alkyl alkali metal compound (JP-A-61-47706, JP-A-63-5402) Olefinic polymers in bond-containing polymers A method of hydrogenating a bond (US Pat. No. 5,244,980), a method in which a titanocene compound is combined with a specified amount of lithium alkoxide to hydrogenate an olefinic double bond in an olefinically unsaturated double bond-containing polymer ( JP-A-1-275605), a method of hydrogenating a conjugated diene polymer in a system in which an organoaluminum compound or the like is present at a specific ratio using a metallocene hydrogenation catalyst (Japanese Patent Application No. 9-252180) But it ’s okay. As the hydrogenation conditions, the method described in each specification can be used in accordance with such a hydrogenation catalyst.
[0010]
Such a hydrogenation catalyst is added in two or more times including the initial one, preferably in 2 to 10 times, more preferably in 2 to 5 times. In this case, the hydrogenation catalyst is added at least once, preferably at a time when the hydrogenation rate of the polymer is 60% to 95%, more preferably at a time of 70% to 95%. It is very important to do. That is, when hydrogenation is carried out in an industrial reaction vessel of 1 m ³ or more using a metallocene-based hydrogenation catalyst, when the hydrogenation rate of the polymer polymer solution increases from 60% to 95%, the viscosity increases significantly. The heat removal capability is deteriorated, and a local temperature rise is likely to occur. In particular, the hydrogenation reaction is a violent exothermic reaction, and this tendency is remarkable. When a local temperature rise occurs, the hydrogenation reaction in that part becomes more and more activated, causing further exotherm, and finally causing a deactivation reaction of the catalyst that loses the activity of the hydrogenation catalyst. For this reason, as a result, troubles such as a decrease in hydrogenation reaction or a failure to obtain a desired high hydrogenation rate polymer are likely to occur. This phenomenon is more conspicuous in larger reactors, and is a major problem in industrial production. However, by adding the catalyst when it reaches such a hydrogenation rate, the required amount of active catalyst can be supplied at the required time, and by adding in multiple stages, the total catalyst usage is rather At least, it is possible to hydrogenate until a polymer having a high hydrogenation rate of 98% or more is obtained reliably and stably in a short time. The hydrogenation catalyst may be activated after the first addition in contact with the polymer, but at least the additional catalyst is activated immediately after the hydrogenation activity is exhibited or in a hydrogen atmosphere. It is preferable to add. As for the hydrogenation catalyst added several times, the initial addition and the post-addition catalyst may not be the same, but the same is preferable from the viewpoint of easy operation. Further, it is not preferable to add it more than 11 times because the operation becomes complicated, and it is not preferable that it is divided into 2 to 10 times, preferably 2 to 5 times, more preferably 2 to 3 times. It is preferable because both efficiency and hydrogenation reliability can be achieved. As a method for discriminating the time when the hydrogenation rate of the polymer is 60% to 95%, more preferably 70% to 95%, which is the catalyst addition time, a method for determining the time when the hydrogenated conjugated diene polymer is used. The determination may be made based on any index such as measurement of the residual amount of heavy bonds, calculation from the amount of hydrogen gas used, change in hydrogen pressure in the hydrogenation vessel, and hydrogenation time. Further, the hydrogenation rate of the polymer is hydrogenated batchwise or continuously and / or batchwise in a specific vessel until the hydrogenation rate of the polymer is 60% to 95%, more preferably 70% to 95%. The remaining portion may be hydrogenated up to 98% in another container or pipe. In any case, hydrogenation can be carried out industrially in a stable and reliable manner by adding the hydrogenation catalyst in such a divided manner. In addition, the hydrogenation rate in this invention means the hydrogenation rate of the conjugated diene unit contained in a polymer.
[0011]
【Example】
The present invention will be specifically described by the following examples, but the present invention is not limited thereto. The synthesis example of each living polymer (A polymer and B polymer) used for the Example was shown to the following manufacture examples.
[0012]
Production Example 1
After putting 4.3 tons of cyclohexane and 0.20 tons of styrene monomer in a 16 m ³ reactor equipped with a stirrer, 4.8 kg of 15% n-butyllithium solution and 0.62 kg of tetramethylethylenediamine were added to the initial temperature. Was set at 70 ° C. and polymerized for 40 minutes under stirring. Subsequently, 3.08 tons of cyclohexane solution containing 30% of 1,3 butadiene monomer was added and polymerized for 1 hour. Further, 0.66 tons of cyclohexane solution containing 30% of styrene monomer was added and polymerization was performed for 40 minutes. The peak temperature during polymerization was 82 ° C. The obtained living polymer (A polymer) has a bound styrene content of 30%, a block styrene content of 30%, a 1,2-vinyl bond content of butadiene units of 37%, and a number average molecular weight of about 230,000. It was a styrene-butadiene-styrene type living block polymer.
[0013]
Production Example 2
After putting 4.85 tons of cyclohexane and 0.33 tons of styrene monomer in a 16 m ³ reactor equipped with a stirrer, 22 kg of 15% n-butyllithium solution was added, and 1.7 kg of tetramethylethylenediamine was further added to the initial temperature. Was set at 70 ° C. and polymerized for 30 minutes with stirring. Next, 5.18 tons of a cyclohexane solution containing 30% of 1,3 butadiene monomer was added and polymerized for 45 minutes. Further, 1.11 tons of cyclohexane solution containing 30% of styrene monomer was added and polymerized for 30 minutes. The peak temperature during polymerization was 85 ° C. The resulting living polymer (B polymer) has a number average molecular weight of about 61,000, with a bound styrene content of 30%, a block styrene content of 30%, and a 1,2-vinyl bond content of butadiene units of 39%. It was a styrene-butadiene-styrene type living block polymer.
[0014]
Example 1
A hydrogenation catalyst was prepared by a method based on the method of JP-A-8-33846. That is, 6 kg of bis (cyclopentadienyl) titanium di-p-tolyl (TPM) is dissolved in 526 kg of cyclohexane, 60 kg of liquid 1,2 polybutadiene is added, and 7.1 kg of 15% butyllithium solution is added. Was added as a hydrogenation catalyst (TPM / Li) by reacting with 0.6 kg of ethanol. On the other hand, as a pretreatment for hydrogenation, the purified polymer was added to the living polymer (A polymer) solution obtained in Production Example 1 to prepare a cyclohexane solution having a polymer concentration of 11%. -Ethyl alcohol was added in an amount of 0.8 equivalent mole of butyl lithium. The entire amount of this polymer solution was transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure was further increased to 0.7 MPa of hydrogen gas. Here, 20 ppm of the hydrogenation catalyst (TPM / Li) prepared earlier was added to the polymer weight based on the weight of Ti, and hydrogenation was started. After 23 minutes, the hydrogenation rate of the polymer in terms of hydrogen gas consumption reached 70%. At this point, 20 ppm of hydrogenation catalyst (TPM / Li) was further added based on the weight of Ti, and hydrogenation was continued. After 35 minutes, the hydrogenation rate of the polymer as seen from the consumption of hydrogen gas became 100%, and the absorption of hydrogen into the polymer solution was also stopped, so the hydrogenation was terminated and the hydrogenation rate of the polymer was measured by the NMR method. It was 99.9%. The maximum temperature reached during hydrogenation was 95 ° C.
[0015]
Comparative Example 1
The living polymer (A polymer) solution obtained in the same manner as in Production Example 1 was pretreated in the same manner as in Example 1, and then transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure of hydrogen gas was 0.7 MPa. To this, a hydrogenation catalyst (TPM / Li) prepared by the same method as in Example 1 was added so as to be 40 ppm relative to the polymer weight on the basis of Ti weight, and hydrogenation was started. After 65 minutes, the hydrogenation rate of the polymer as determined from the consumption of hydrogen gas was 97%, but the absorption of hydrogen into the polymer solution almost stopped, so the hydrogenation was terminated. The hydrogenation rate of the final polymer by NMR method was 96.8%. The maximum temperature reached during hydrogenation was 100 ° C.
[0016]
Example 2
As a pretreatment, after adding purified and dried cyclohexane to the living polymer (B polymer) obtained in Production Example 2 to prepare a cyclohexane solution having a polymer concentration of 19%, ethyl alcohol was adjusted to 0.9% of n-butyllithium. An equimolar mole was added. Subsequently, the entire amount of this polymer solution was transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure was further increased to 0.7 MPa of hydrogen gas. Hydrogenation catalyst (TPM / Li) prepared by the same method as in Example 1 was added to the reaction vessel so as to be 10 ppm relative to the polymer weight based on Ti weight, and hydrogenation was started. After 35 minutes, the hydrogenation rate of the polymer in terms of hydrogen gas consumption reached 61%. At this point, a hydrogenation catalyst (TPM / Li) was added in an amount of 5 ppm based on the Ti weight, and hydrogenation was continued. did. After 40 minutes, when the hydrogenation rate of the polymer in terms of hydrogen gas consumption was 85%, 5 ppm was further added based on the weight of Ti, and hydrogenation was continued. After 45 minutes, the hydrogenation rate of the polymer as seen from the consumption of hydrogen gas was 100%, and the absorption of hydrogen into the polymer solution was stopped, so the hydrogenation was terminated and the hydrogenation rate of the polymer was measured by NMR method. It was 99.8%. The maximum temperature reached during hydrogenation was 90 ° C.
[0017]
Comparative Example 2
The living polymer (B polymer) solution obtained in the same manner as in Production Example 2 was pretreated in the same manner as in Example 2, and then transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure was further increased to 0.7 MPa of hydrogen gas. Further, 20 ppm of a hydrogenation catalyst (TPM / Li) prepared by the same method as in Example 1 was added to the polymer weight based on the weight of Ti, and hydrogenation was started. After 105 minutes, the hydrogenation rate of the polymer as seen from the consumption of hydrogen gas was 85%, but the absorption of hydrogen into the polymer solution was almost stopped. The hydrogenation rate was measured and found to be 85.1%. The maximum temperature reached during hydrogenation was 95 ° C.
[0018]
Example 3
A hydrogenation catalyst was prepared by a method based on the method of Japanese Patent Application No. 9-252180. 5 kg of bis (cyclopentadienyl) titanium dichloride was added to 70.1 kg of cyclohexane, and after stirring, 24.9 kg of 10% trimethylaluminum solution was added and reacted for 72 hours to prepare a hydrogenation catalyst (TC / TMAL) solution. . On the other hand, the same living polymer (A polymer) solution as that obtained in Production Example 1 was pretreated in the same manner as in Example 1, and then transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure was further increased to 0.7 MPa of hydrogen gas. Here, the hydrogenation catalyst (TC / TMAL) prepared earlier was added at 30 ppm with respect to the polymer weight based on the weight of Ti, and hydrogenation was started. After 20 minutes, the hydrogenation rate of the polymer as seen from the consumption of hydrogen gas was 65%. At this point, 20 ppm of hydrogenation catalyst (TC / TMAL) was further added based on the Ti weight, and the hydrogenation was continued. After 23 minutes, when the hydrogenation rate of the polymer in terms of hydrogen gas consumption reached 80%, 10 ppm of hydrogenation catalyst (TC / TMAL) was further added based on the weight of Ti, and hydrogenation was continued. Further, 27 minutes after the start of hydrogenation, when the hydrogenation rate of the polymer as viewed from the consumption of hydrogen gas reached 90%, an additional 10 ppm of hydrogenation catalyst (TC / TMAL) was added based on the Ti weight, Continued to follow. After 30 minutes, the hydrogenation rate of the polymer as seen from the consumption of hydrogen gas was 100%, and the absorption of hydrogen into the polymer solution was stopped, so the hydrogenation was terminated and the hydrogenation rate of the polymer was measured by NMR method. 100%. The maximum temperature reached during hydrogenation was 98 ° C.
[0019]
Comparative Example 3
The living polymer (A polymer) solution obtained in the same manner as in Production Example 1 was pretreated in the same manner as in Example 1, and then transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at 80 ° C. with stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure of hydrogen gas was further increased to 0.7 MPa. Further, hydrogenation catalyst (TC / TMAL) prepared in the same manner as in Example 3 was added at 70 ppm based on the weight of Ti, based on the weight of the polymer, and hydrogenation was started. The hydrogenation rate of the polymer as seen from the consumption of hydrogen gas after 30 minutes was 91%, absorption of hydrogen into the polymer solution almost stopped, and the hydrogenation rate of the polymer by NMR method was 91.0%. there were. The maximum temperature reached during hydrogenation was 102 ° C.
[0020]
Example 4
The living polymer (B polymer) solution obtained in the same manner as in Production Example 2 was pretreated in the same manner as in Example 2, and then transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure was further increased to 0.7 MPa of hydrogen gas. Furthermore, hydrogenation catalyst (TC / TMAL) prepared by the same method as in Example 3 was added at 15 ppm based on the weight of Ti, based on the weight of the polymer, and hydrogenation was started. After 25 minutes, the hydrogenation rate of the polymer as viewed from the amount of hydrogen gas consumed reached 75%. At this point, 5 ppm of hydrogenation catalyst (TC / TMAL) was added based on the Ti weight, and hydrogenation was continued. After 29 minutes, when the hydrogenation rate of the polymer as determined from the consumption amount of hydrogen gas was 88%, 5 ppm of hydrogenation catalyst (TC / TMAL) was further added based on the Ti weight, and the hydrogenation was continued. Further, 32 minutes after the start of hydrogenation, when the hydrogenation rate of the polymer in terms of hydrogen gas consumption was 93%, an additional 5 ppm of hydrogenation catalyst (TC / TMAL) was added based on the weight of Ti, and the hydrogenation was continued. . After 35 minutes, the hydrogenation rate of the polymer as seen from the consumption of hydrogen gas became 100%, and the absorption of hydrogen into the polymer solution was also stopped, so the hydrogenation was terminated and the hydrogenation rate of the polymer was measured by the NMR method. It was 99.9%. The maximum temperature reached during hydrogenation was 89 ° C.
[0021]
Comparative Example 4
The living polymer (B polymer) solution obtained in the same manner as in Production Example 2 was pretreated in the same manner as in Example 2, and then transferred to a 20 m ³ reactor equipped with a stirrer. After setting the inside of the reactor at an initial temperature of 80 ° C. under stirring, the inside of the reactor was replaced with hydrogen gas, and the pressure was further increased to 0.7 MPa of hydrogen gas. Further, hydrogenation catalyst (TC / TMAL) prepared by the same method as in Example 3 was added at 30 ppm with respect to the polymer weight based on the weight of Ti, and hydrogenation was started. After 70 minutes, the hydrogenation rate of the polymer in terms of hydrogen gas consumption was 89%, and the absorption of hydrogen into the polymer solution almost stopped. At this time, the hydrogenation rate of the polymer by NMR method was 89.2%. The maximum temperature reached during hydrogenation was 98 ° C.
[0022]
Table 1 summarizes the hydrogenation conditions and results of Examples 1 to 4 and Comparative Examples 1 to 4 described above.
[0023]
[Table 1]

[0024]
【The invention's effect】
In order to obtain a conjugated diene polymer having a hydrogenation rate of 98% or more industrially using a large reaction vessel of 1 m ³ or more, the present invention provides a hydrogenation catalyst when hydrogenating using a metallocene hydrogenation catalyst. Is added in several steps to provide an industrially extremely advantageous method that can stably hydrogenate stably in a short time with a small amount of hydrogenation catalyst.

Claims

A hydrogenation method in a large reaction vessel of 1 m ³ or more, wherein a conjugated diene polymer obtained by polymerizing an organic alkali metal compound as a polymerization initiator is hydrogenated using a metallocene hydrogenation catalyst, and a hydrogenation rate An improved method for hydrogenating a conjugated diene polymer, characterized in that, when 98% or more of a conjugated diene polymer is obtained, the hydrogenation catalyst is added in two or more steps to proceed with hydrogenation.

2. The hydrogenation of an improved conjugated diene polymer according to claim 1, wherein the hydrogenation catalyst is added one or more times when the hydrogenation rate of the conjugated diene polymer is 60% to 95%. Method.