JP3683471B2 - Method for producing aromatic polycarbonate - Google Patents

Description

【００１１】
（式中、Ａ及びＡ’は、炭素数１〜１８の、置換されていてもよい、脂肪族基又は芳香族基であり、ＡとＡ’とは、同一でも異なってもよい。）
【００１２】
式（１）で表される炭酸ジエステル化合物の具体例としては、例えば、ジメチルカーボネート、ジエチルカーボネート、ジ−ｔ−ブチルカーボネート、ジフェニルカーボネート及びジトリルカーボネート等の置換ジフェニルカーボネート等があるが、好ましくはジフェニルカーボネート、置換ジフェニルカーボネートがあり、特にジフェニルカーボネートが好ましい。これらの炭酸ジエステル化合物は、単独でも、２種以上を混合して用いてもよい。
【００１３】
また、上記のような炭酸ジエステル化合物と共に、好ましくは５０％以下、さらに好ましくは３０モル％以下の量でジカルボン酸、あるいはジカルボン酸エステルを使用してもよい。このようなジカルボン酸あるいはジカルボン酸エステルとしては、テレフタル酸、イソフタル酸、テレフタル酸ジフェニル、イソフタル酸ジフェニル等が用いられる。このようなカルボン酸、あるいはカルボン酸エステルを炭酸ジエステル化合物と併用した場合には、ポリエステルカーボネートが得られる。
【００１４】
芳香族ジヒドロキシ化合物
もう一つの原料である芳香族ジヒドロキシ化合物は、下記式（２）で示される。
【００１５】
【化２】

【００１６】
（式中、Ｂは、１〜１５の炭素数を有する２価の炭化水素基、ハロゲン置換の２価の炭化水素基、−Ｓ−基、−ＳＯ₂ −基、−ＳＯ−基、−Ｏ−基又は−ＣＯ−基を示し、Ｘは、ハロゲン原子、炭素数１〜１４のアルキル基、炭素数６〜１８のアリール基、炭素数１〜８のオキシアルキル基又は炭素数６〜１８のオキシアリール基を示す。ｍは、０又は１であり、ｙは、０〜４の整数である。）
【００１７】
式（２）で表される芳香族ジヒドロキシ化合物としては、例えば、２，２−ビス（４−ヒドロキシフェニル）プロパン、２，２−ビス（４−ヒドロキシ−３，５−ジメチルフェニル）プロパン、２，２−ビス（４−ヒドロキシ−３，５−ジエチルフェニル）プロパン、２，２−ビス（４−ヒドロキシ−（３，５−ジフェニル）フェニル）プロパン、２，２−ビス（４−ヒドロキシ−３，５−ジブロモフェニル）プロパン、２，２−ビス（４−ヒドロキシフェニル）ペンタン、２，４’−ジヒドロキシ−ジフェニルメタン、ビス（４−ヒドロキシフェニル）メタン、ビス（４−ヒドロキシ−５−ニトロフェニル）メタン、１，１−ビス（４−ヒドロキシフェニル）エタン、３，３−ビス（４−ヒドロキシフェニル）ペンタン、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサン、ビス（４−ヒドロキシフェニル）スルホン、２，４’−ジヒドロキシジフェニルスルホン、ビス（４−ヒドロキシフェニル）スルフィド、４，４’−ジヒドロキシジフェニルエーテル、４，４’−ジヒドロキシ−３，３’−ジクロロジフェニルエーテル、４，４’−ジヒドロキシ−２，５−ジエトキシジフェニルエーテル等が例示される。これらの中でも、２，２−ビス（４−ヒドロキシフェニル）プロパンが好ましい。また、これらの芳香族ジヒドロキシ化合物は、単独で又は２種以上を混合して、用いることができる。
【００１８】
炭酸ジエステル化合物と芳香族ジヒドロキシ化合物との混合比率は、所望する芳香族ポリカーボネートの分子量と末端ヒドロキシ基量により決められる。末端ヒドロキシ基量は、製品ポリカーボネートの熱安定性と加水分解安定性に大きな影響を及ぼし、実用的な物性を持たせるためには１０００ｐｐｍ以下にすることが必要となる。従って、芳香族ジヒドロキシ化合物１モルに対して炭酸ジエステル化合物を等モル量以上用いるのが一般的であり、１．０１〜１．３０モル、好ましくは１．０１〜１．２０モルの量で用いるのが望ましい。
【００１９】
撹拌槽（３）、（６）は、いずれも垂直回転軸に取り付けられた撹拌翼を有しているが、翼の形式は、所望の混合が達成され、未溶解物を含まない均一溶液を調製しうるならば、特に制限はない。また、図示の場合は、第１撹拌槽（３）と移送配管（４）で連結された第２撹拌槽（６）を最終撹拌槽とするが、所望の混合を達成するために必要ならば、第１撹拌槽（３）と第２撹拌槽（６）の間に、さらに移送配管（４）で連結された撹拌槽（６）を設けてもよい。これら２以上の撹拌槽（３）、（６）における両原料の混合は、炭酸ジエステルの融点以上、芳香族ジヒドロキシ化合物の融点以下の温度で行うのが好ましい。例えば、ＤＰＣとＢＰＡの混合の場合は、ＤＰＣの融点８０℃以上、ＢＰＡの融点１５６℃以下の温度が選ばれるが、ＢＰＡは１５０℃を超えると分解して着色物質を生成し、１２０℃以下では、溶融ＤＰＣへの溶解速度が低下するので、通常、１２０℃〜１５０℃の温度、好ましくは１４０℃前後の温度で、両原料の混合が行われる。
【００２０】
しかし、この移送配管（４）は、例えばコントロールバルブや内径の異なる配管のような流路狭窄部のないものを使用することが必要である。また、１の撹拌槽（３）から次の撹拌槽（６）への原料混合物の移送は、静水圧のみによって行うことが必要である。これを実行するには、該１の撹拌槽（３）の液面は、次の撹拌槽（６）の液面より上のレベルとし、該１の撹拌槽と次の撹拌槽を連結する移送配管（４）中の最高位が、該１の撹拌槽（３）の液面と同レベルであることが好ましい。撹拌槽の液面は、任意に決めることができるが、液面が低すぎると溶解時間が短くなり、未反応の原料が、重合槽へ流入する可能性が高くなる。また、液面が高すぎると、撹拌槽の滞留時間が長くなり、原料が着色し、得られるポリカーボネートの色相が悪化する要因になる。通常、液面は、各撹拌槽の滞留時間が０．５時間〜２時間、好ましくは０．５〜１．５時間となるように設定することが好ましい。また、全ての撹拌槽（３）、（６）及び移送配管（４）を通過するに要する原料混合物の全滞留時間は、３００分以内、好ましくは２４０分以内、特に好ましくは１８０分以内とすることが好ましい。
１の撹拌槽（３）の液面が、移送配管（４）中の最高位を超えると、該撹拌槽中の原料混合物は、移送配管（４）を通って次の撹拌槽（６）に移送される。移送配管の配管径は、あまり太いと滞留時間が長くなるため流速が０．０６ｍ／ｓｅｃ以上であるような配管径が好ましい。
【００２１】
＜重縮合反応＞
エステル交換触媒
エステル交換法により芳香族ポリカーボネートを製造する際には、通常エステル交換触媒が使用される。エステル交換触媒としては、主として、アルカリ金属化合物及び／又はアルカリ土類金属化合物が使用され、補助的に、塩基性ホウ素化合物、塩基性リン化合物、塩基性アンモニウム化合物あるいはアミン系化合物等の塩基性化合物を併用することも可能である。これらの触媒は、１種類で使用してもよく、２種以上を組み合わせて使用してもよい。
【００２２】
触媒量は、通常、芳香族ジヒドロキシ化合物１モルに対して、１×１０^-8〜１×１０^-5モルの範囲で用いられる。この量より少なければ、所定の分子量、末端ヒドロキシ基量のポリカーボネートを製造するのに長時間必要な重合活性が得られず、この量より多い場合は、ポリマー色相が悪化し、ゲルの発生による異物量も増大する傾向となる。特に、アルカリ金属化合物及び／又はアルカリ土類金属化合物を用いる場合、それらの金属量として１×１０^-8〜２×１０^-6モルの範囲が好ましく、０．５×１０^-7〜１×１０^-6モルの範囲が特に好ましい。
【００２３】
アルカリ金属化合物としては、リチウム、ナトリウム、カリウム、ルビジウム、セシウムの水酸化物、炭酸水素塩、炭酸塩、酢酸塩、リン酸水素塩、フェニルリン酸塩等の無機アルカリ金属化合物や、ステアリン酸、安息香酸等の有機酸類、メタノール、エタノール等のアルコール類，石炭酸、ビスフェノールＡ等のフェノール類との塩等の有機アルカリ金属化合物等が挙げられる。アルカリ土類金属化合物としては、ベリリウム、カルシウム、マグネシウム、ストロンチウム、バリウムの水酸化物、炭酸水素塩、炭酸塩、酢酸塩等の無機アルカリ土類金属化合物や、有機酸類、アルコール類、フェノール類との塩等の有機アルカリ土類金属化合物等が挙げられる。
【００２４】
塩基性ホウ素化合物の具体例としては、テトラメチルホウ素、テトラエチルホウ素、テトラプロピルホウ素、テトラブチルホウ素、トリメチルエチルホウ素、トリメチルベンジルホウ素、トリメチルフェニルホウ素、トリエチルメチルホウ素、トリエチルベンジルホウ素、トリエチルフェニルホウ素、トリブチルベンジルホウ素、トリブチルフェニルホウ素、テトラフェニルホウ素、ベンジルトリフェニルホウ素、メチルトリフェニルホウ素、ブチルトリフェニルホウ素、等の水素化物、ナトリウム塩、カリウム塩、リチウム塩、カルシウム塩、マグネシウム塩、バリウム塩、或いはストロンチウム塩等が挙げられる。
【００２５】
塩基性リン化合物としては、例えば、トリエチルホスフィン、トリ−ｎ−プロピルホスフィン、トリイソプロピルホスフィン、トリ−ｎ−ブチルホスフィン、トリフェニルホスフィン、トリブチルホスフィン、あるいは四級ホスホニウム塩等が挙げられる。
【００２６】
塩基性アンモニウム化合物としては、例えば、テトラメチルアンモニウムヒドロキシド、テトラエチルアンモニウムヒドロキシド、テトラプロピルアンモニウムヒドロキシド、テトラブチルアンモニウムヒドロキシド、トリメチルエチルアンモニウムヒドロキシド、トリメチルベンジルアンモニウムヒドロキシド、トリメチルフェニルアンモニウムヒドロキシド、トリエチルメチルアンモニウムヒドロキシド、トリエチルベンジルアンモニウムヒドロキシド、トリエチルフェニルアンモニウムヒドロキシド、トリブチルベンジルアンモニウムヒドロキシド、トリブチルフェニルアンモニウムヒドロキシド、テトラフェニルアンモニウムヒドロキシド、ベンジルトリフェニルアンモニウムヒドロキシド、メチルトリフェニルアンモニウムヒドロキシド、ブチルトリフェニルアンモニウムヒドロキシド等が挙げられる。
【００２７】
アミン系化合物としては、例えば、４−アミノピリジン、２−アミノピリジン、Ｎ，Ｎ−ジメチル−４−アミノピリジン、４−ジエチルアミノピリジン、２−ヒドロキシピリジン、２−メトキシピリジン、４−メトキシピリジン、２−ジメチルアミノイミダゾール、２−メトキシイミダゾール、イミダゾール、２−メルカプトイミダゾール、２−メチルイミダゾール、アミノキノリン等が挙げられる。
【００２８】
芳香族ポリカーボネート
芳香族ポリカーボネートは、二段階以上の多段工程で製造される。一般的には、反応温度１４０〜３２０℃、反応時間０．１〜５時間、圧力は常圧より段階を追って減圧度を上げ、副生するモノフェノール化合物をラインから連続的に除去しながら、重縮合反応を行う。最終的には２６７Ｐａ以下の減圧下、２５０〜３２０℃の温度で重縮合反応を行い、粘度平均分子量１００００〜１０００００、好ましくは１２０００〜４００００に高分子量化する。必要に応じて、窒素等の不活性ガスを流通させることもできる。また、モノフェノール化合物に同伴する原料化合物を重合槽に戻すために、分留塔を重合槽に付設することもできる。
【００２９】
反応の方式は、バッチ式、連続式、又はバッチ式と連続式の組合せのいずれでもよい。使用する装置は、槽型、管型又は塔型のいずれの形式であってもよく、例えば、ファウドラー翼、アンカー翼、タービン翼、ダブルヘリカル翼、マックスブレンド翼等、各種の撹拌翼を具備した竪型重合槽、横型１軸タイプの重合槽又は／及び横型２軸タイプの重合槽等を使用することができる。
【００３０】
反応は、実質的に無酸素下で行われることが好ましく、例えば、運転開始前に原料調製槽、重合槽及び配管内を窒素ガス等の不活性ガスで置換しておく。通常、芳香族ジヒドロキシ化合物と炭酸ジエステル化合物との溶融混合物を、竪型重合槽に供給する。触媒は、原料とは別のラインで第１重合槽に直接供給してもよいし、第１重合槽に入る手前の配管内で、スタティックミキサー等により原料と混合した状態で供給させてもよい。さらに、第１重合槽に供給される原料混合物を調製する最終撹拌槽に添加してもよい。原料調整槽で触媒を添加する利点は、温度が重合槽より低いことにある。一般に、ＢＰＡは１６０℃以上になると分解して着色物質を生成する。このため、１４０℃で触媒を添加するとＢＰＡはＤＰＣと一部反応し、熱に対して安定化する。また、触媒を原料に分散させるためにも、ある一定時間が必要となり、原料調製槽に添加して分散及び反応時間を稼ぐために有利となる。必要に応じて、触媒を溶解あるいは懸濁するための溶媒が用いられる。好ましい溶媒としては、水、アセトン、フェノール等が挙げられる。
【００３１】
重合液供給口は、反応槽側壁液相部にあり、抜き出し口は、反応槽底部にあるのが好ましい。また、各槽から反応液を連続して抜き出す方法は、落差を利用する方法、圧力差を利用する方法、ギアポンプ等の送液ポンプを用いる方法等、反応液の物性に適応した方法で行うのが好ましい。
【００３２】
添加剤
本発明に使用される添加剤として、アルカリ金属化合物等の触媒を用いる場合には、ポリカーボネート中に残存する触媒を中和するために、酸性化合物、特にはイオウ含有酸性化合物を、触媒金属に対して０．５〜１０当量、好ましくは１〜５当量を添加することができる。すなわち、通常０．０１〜２０ｐｐｍ、好ましくは０．１〜１０ｐｐｍ、さらに好ましくは３〜７ｐｐｍ添加する。
【００３３】
イオウ含有酸性化合物の例としては、スルホン酸、スルフィン酸又はそれらのエステル誘導体であり、具体的には、ｐ−トルエンスルホン酸、ベンゼンスルホン酸及びドデシルベンゼンスルホン酸、それらのメチル、エチル、ブチル、ｔ−ブチル、オクチル、ドデシル、フェニル、ベンジル、フェネチル等のエステル類、ベンゼンスルフィン酸、トルエンスルフィン酸、ナフタレンスルホン酸等が挙げられる。これらの化合物の内、ｐ−トルエンスルホン酸のエステル又はベンゼンスルホン酸のエステルが好ましく、これらの化合物を２種以上使用してもよい。さらに、これらの化合物のアルカリ金属塩を、これらの化合物と併用すると、分散性が向上し失活効果が高まるので好ましい。併用する量としては、非アルカリ金属塩に対してアルカリ金属塩を、重量比で０．３〜３倍程度の量用いることが好ましい。
【００３４】
イオウ含有酸性化合物のポリカーボネートへの添加方法は、任意の方法により行うことができる。例えば、イオウ含有酸性化合物を、直接又は希釈剤で希釈して、溶融又は固体状態にあるポリカーボネートに添加し、分散させることができる。具体的には、重縮合反応器中、反応器からの移送ライン中、押出機中に供給して混合することができ、通常は押出機中に供給される。また、ミキサー等で、ポリカーボネートや、他種ポリマーのペレット、フレーク、粉末等と混合後、押出機に供給して混練することもできる。これらのうちポリカーボネートのフレークに、イオウ含有酸性化合物の原液を添加し、ミキサー等で混合後、マスターバッチとして添加することが好ましい。さらに、添加の際には、重量フィーダー等を用いて、添加量を精度良く制御することが好ましい。
【００３５】
また押出機で、ベントによる減圧処理を行う場合、又は水添加、熱安定剤、離型剤、染料、顔料、紫外線吸収剤、帯電防止剤、防曇剤、有機・無機充填剤等を添加する場合は、これらの添加及び処理は、イオウ含有酸性化合物と同時に行ってもよいが、イオウ含有酸性化合物を最初に添加、混練することが好ましい。
押出機は、脱気機能を備えたものであればどのような形式のものでもよい。具体的には、ベント式の単軸又は多軸押出機が挙げられるが、特に噛み合い型二軸押出機が好ましく、回転方向は同方向回転でも、異方向回転でもよい。ベント数は制限はないが、通常は、２段から１０段の多段ベントが用いられる。
【００３６】
【実施例】
以下、本発明を実施例により説明するが、本発明はこれら実施例に限定されるものではない。なお、得られた芳香族ポリカーボネートの分析は下記の測定方法により行った。
【００３７】
（１）粘度平均分子量（Ｍｖ）
ウベローデ粘度計を用いて、塩化メチレン中２０℃の極限粘度［η］を測定し、以下の式より粘度平均分子量（Ｍｖ）を求めた。
［η］＝１．２３×１０^-4×（Ｍｖ）^0.83
【００３８】
（２）色相
ポリカーボネートを、窒素雰囲気下、１２０℃で６時間以上乾燥した後、（株）日本製鋼所製Ｊ−１００ＳＳ−２射出成形機を用いて、バレル温度２８０℃、金型温度９０℃の条件下にて成形した、厚み３ｍｍ、一辺１００ｍｍ角の射出成形品について、スガ試験機（株）製カラーテスターＳＣ−１−ＣＨで、色の絶対値である三刺激値ＸＹＺを測定し、次の関係式により黄色度の指標であるＹＩ値を算出した。
ＹＩ＝（１００／Ｙ）×（１．２８Ｘ−１．０６Ｚ）
このＹＩ値が大きいほど着色していることを示す。
【００３９】
実施例１
原料溶液調製
図１に示すフローシートにおいて、窒素ガス雰囲気下、ＢＰＡ（供給速度４４．９ｋｇ／ｈ）及びＤＰＣ（供給速度４４．７ｋｇ／ｈ）を、原料導入管（１）及び（２）により、１４０℃に設定された、内容積０．２ｍ³ でアンカー型撹拌翼を備えた第１撹拌槽（３）に連続的に導入した。同撹拌槽（３）の液面が移送配管（４）中の最高位と同じ高さ（撹拌槽（３）の内容積０．１３ｍ³ に相当）を超えると、原料混合物が内容積０．２ｍ³ でアンカー型撹拌翼を備えた第２撹拌槽（６）に、両撹拌槽を連結する内径１７．５ｍｍの移送配管（４）中を、０．１４ｍ／ｓｅｃの速度で移送される。撹拌槽（３）、（６）及び移送配管（４）を通過するに要した原料混合物の全滞留時間は、１６０分であった。上記原料混合物が第２撹拌槽（６）に移送されたのと同時に、触媒として０．１６％水溶液状の炭酸セシウムを、ＢＰＡ１モルに対し０．５×１０^-6モルの流量で、触媒導入管（５）より、同撹拌槽（６）への連続的導入を開始した。
【００４０】
重縮合反応
撹拌槽（６）への移送開始１時間後に、同槽で調製された、ＢＰＡを完全溶解し未溶解物を含まない原料溶液を供給配管（７）、（９）を介して、常圧、窒素雰囲気下２１０℃に制御した第１竪型撹拌重合槽に連続供給した。該重合槽での平均滞留時間が６０分になるように、槽底部のポリマー排出ラインに設けられたバルブ開度を制御しつつ、液面レベルを一定に保つた。
【００４１】
第１重合槽底より排出された重合液は、引き続き第２、第３及び第４の竪型重合槽並びに第５の横型撹拌重合槽に、逐次、連続供給された。反応の間、各槽の平均滞留時間が６０分になるように液面レベルを制御し、また同時に副生するフェノールの留去も行つた。これら重合槽では、それぞれ、第２重合槽（２１０℃、１３３００Ｐａ）、第３重合槽（２４０℃、１９９５Ｐａ）、第４重合槽（２６０℃、６７Ｐａ）、第５重合槽（２６５℃、６７Ｐａ）と、反応の進行とともに高温、高真空、低撹拌速度となるように、重合条件を設定した。芳香族ポリカーボネートの製造速度は５０ｋｇ／ｈである。得られたポリカーボネートの分子量は１５５００であった。
【００４２】
このポリマーを、溶融状態のまま、２軸押出機（神戸製鋼所（株）製、４６ｍｍφ噛み合いスクリュー、同方向）に導入し、ｐ−トルエンスルホン酸ブチルを５ｐｐｍ添加した後、ぺレット化した。得られたポリマーの色相は、１．６であった。
【００４３】
比較例１（単一撹拌槽、コントロールバルブによる液面制御）
図１に示すフローシートに代え、図２に示すフローシートを用いた以外は、実施例１と同様な操作を行った。運転開始直後に、未溶解のＢＰＡがコントロールバルブ１１に詰まって、運転の継続が不可能になった。
【００４４】
比較例２（第１撹拌槽はコントロールバルブによる液面制御）
図１に示すフローシートに代え、図３に示すフローシートを用いた以外は、実施例１と同様な操作を行った。運転開始直後に、比較例１と同様、未溶解のＢＰＡがコントロールバルブ１１に詰まって、運転の継続が不可能になった。
【００４５】
【発明の効果】
本発明によれば、移送配管の閉塞がなく、色相に優れたエステル交換法芳香族ポリカーボネートが得られる。
【図面の簡単な説明】
【図１】 実施例１の原料溶液調製を示すフローシート図。
【図２】 比較例１の原料溶液調製を示すフローシート図。
【図３】 比較例２の原料溶液調製を示すフローシート図。
【符号の説明】
１、２ 原料導入管
３ 第１撹拌槽
４ 移送配管
５ 触媒導入管
６ 第２撹拌槽
７、９ 重合系への供給配管
８ ポンプ
１０ 液面計
１１ コントロールバルブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aromatic polycarbonate by a transesterification method of an aromatic dihydroxy compound and a carbonic acid diester compound, and particularly provides an aromatic polycarbonate excellent in hue, thermal stability, and hydrolysis stability. .
[0002]
[Prior art]
In recent years, aromatic polycarbonate has been widely used in many fields as engineering plastics excellent in heat resistance, impact resistance, transparency and the like. Various methods have been conventionally studied for producing this aromatic polycarbonate. Among them, aromatic dihydroxy compounds such as 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) are used. The interfacial polycondensation method with phosgene has been industrialized.
In addition, the so-called transesterification method, in which a polycarbonate is produced by polycondensation of a carbonic diester compound and an aromatic dihydroxy compound, has a relatively simple process compared to the above-mentioned interfacial polycondensation method. In addition to being superior in terms of surface quality, it has the advantage of being environmentally friendly in that it does not use highly toxic phosgene or halogen solvents such as methylene chloride. It is done.
However, the transesterification method polymerizes at a higher temperature than the interfacial polycondensation method, and thus has a problem that the aromatic polycarbonate of the product is easily colored.
[0003]
In order to solve these problems, various proposals have been made so far. For example, improvement of the catalyst (Japanese Patent Laid-Open Nos. 55-142025, 2-124934, 2-212518), material of the reactor and surface treatment (US Pat. No. 4,383,092, Japanese Patent Laid-Open No. 4-7328) And JP-A-4-72327) and examination of additives (JP-A-4-15223, JP-A-36344, JP-A-41525) and the like. However, the problem of coloring during preparation of the raw material solution is not mentioned.
In JP-A-6-32887, powdered bisphenol A (abbreviated as BPA) is dissolved in molten diphenyl carbonate (abbreviated as DPC) in the absence of oxygen at a temperature below the melting point of BPA. Although it has been proposed to do so, no mention is made of problems during the transfer of such solutions.
[0004]
Such a raw material solution preparation method is roughly classified into a batch type and a continuous type. In the case of the batch type, the raw materials BPA and DPC are measured by weight, put into a stirring tank, and completely dissolved before use. The advantage of this method is that the operation is simple and the design of the apparatus is easy. However, since the residence time after dissolution becomes long, the raw material itself is colored, which is one of the causes of deterioration of the color of the polycarbonate as a product.
On the other hand, in the case of a continuous type, since the residence time of each tank becomes short, the quality deterioration of a raw material is suppressed as much as possible, and a polycarbonate with a good hue is obtained. However, when BPA is continuously dissolved in molten DPC, if the device design is incorrect, BPA is sent to the polymerization tank without being dissolved, and as a result, the balance of terminal OH is lost, and the aromatic polycarbonate after polymerization is lost. Adversely affects the physical properties. Further, such undissolved BPA is blocked at a flow path constricted portion in the transfer pipe, for example, at a place such as a control valve, causing trouble that makes the operation impossible.
[0005]
[Problems to be solved by the invention]
In the production of an aromatic polycarbonate by transesterification of an aromatic dihydroxy compound and a carbonic acid diester compound, the present invention has a short raw material residence time and no clogging of a transfer pipe, so that the raw material is less colored and the hue is excellent. An object is to provide an aromatic polycarbonate. As a result of diligent studies, the present inventors have found that a solution that is completely dissolved before being supplied to the polymerization system to be a uniform solution, that has a short residence time, and that does not have a channel narrowing portion is required for the transfer pipe. It was. Specifically, in preparing the raw material solution, two or more agitation tanks connected by a transfer pipe without the above-mentioned channel narrowing part are used, and transfer to the next agitation tank is performed only by hydrostatic pressure. This makes it possible to satisfy all the above requirements.
[0006]
[Means for Solving the Problems]
That is, the present invention relates to a method for producing an aromatic polycarbonate by polycondensation of an aromatic dihydroxy compound and a carbonic acid diester in the presence of a transesterification reaction catalyst. When two or more connected stirring tanks are used to continuously mix and prepare a homogeneous solution that does not contain undissolved material, and supply it to the polymerization system, the transfer pipe does not have a channel constriction. And a raw material mixture in the stirring tank is transferred to the next stirring tank only by hydrostatic pressure.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a flowchart showing an example of an embodiment of the present invention. In the figure, 1 and 2 are raw material introduction pipes, 3 is a first stirring tank, 4 is a transfer pipe, 5 is a catalyst introduction pipe, 6 is a second stirring tank, 7 and 9 are supply pipes to the polymerization system, and 8 is a pump. 10 is a liquid level gauge, and 11 is a control valve.
[0008]
<Preparation of raw material solution>
As a raw material for producing the aromatic polycarbonate according to the present invention, a carbonic acid diester compound and an aromatic dihydroxy compound are used. These are continuously introduced into the first stirring tank (3) by the raw material introduction pipes (1) and (2), respectively, in order to prepare the raw material solution to be supplied to the polymerization system. Both raw material compounds are usually solid at room temperature, but if necessary, one raw material may be introduced by heating and melting in advance. In general, the carbonic acid diester compound is often lower in melting point than the aromatic dihydroxy compound, and is easily decomposed when the aromatic dihydroxy compound is melted. The aromatic dihydroxy compound is introduced as a solid.
[0009]
Carbonic acid diester compound
The carbonic acid diester compound is represented by the following formula (1).
[0010]
[Chemical 1]

[0011]
(In the formula, A and A ′ are an aliphatic group or an aromatic group having 1 to 18 carbon atoms which may be substituted, and A and A ′ may be the same or different.)
[0012]
Specific examples of the carbonic acid diester compound represented by the formula (1) include substituted diphenyl carbonates such as dimethyl carbonate, diethyl carbonate, di-t-butyl carbonate, diphenyl carbonate, and ditolyl carbonate. There are diphenyl carbonate and substituted diphenyl carbonate, and diphenyl carbonate is particularly preferable. These carbonic acid diester compounds may be used alone or in admixture of two or more.
[0013]
Further, together with the carbonic acid diester compound as described above, dicarboxylic acid or dicarboxylic acid ester may be used preferably in an amount of 50% or less, more preferably 30 mol% or less. Examples of such dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate. When such carboxylic acid or carboxylic acid ester is used in combination with a carbonic acid diester compound, polyester carbonate is obtained.
[0014]
Aromatic dihydroxy compounds
Another raw material, an aromatic dihydroxy compound, is represented by the following formula (2).
[0015]
[Chemical 2]

[0016]
(In the formula, B is a divalent hydrocarbon group having 1 to 15 carbon atoms, a halogen-substituted divalent hydrocarbon group, an —S— group, —SO;₂ -Group, -SO- group, -O- group or -CO- group, wherein X is a halogen atom, an alkyl group having 1 to 14 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkyl group having 1 to 8 carbon atoms. An oxyalkyl group or an oxyaryl group having 6 to 18 carbon atoms is shown. m is 0 or 1, and y is an integer of 0-4. )
[0017]
Examples of the aromatic dihydroxy compound represented by the formula (2) include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, , 2-bis (4-hydroxy-3,5-diethylphenyl) propane, 2,2-bis (4-hydroxy- (3,5-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3) , 5-Dibromophenyl) propane, 2,2-bis (4-hydroxyphenyl) pentane, 2,4′-dihydroxy-diphenylmethane, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-5-nitrophenyl) Methane, 1,1-bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4 Hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone, 2,4′-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) sulfide, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3 Examples include '-dichlorodiphenyl ether, 4,4'-dihydroxy-2,5-diethoxydiphenyl ether, and the like. Among these, 2,2-bis (4-hydroxyphenyl) propane is preferable. Moreover, these aromatic dihydroxy compounds can be used individually or in mixture of 2 or more types.
[0018]
The mixing ratio of the carbonic acid diester compound and the aromatic dihydroxy compound is determined by the molecular weight and the terminal hydroxy group amount of the desired aromatic polycarbonate. The amount of terminal hydroxy groups has a great influence on the thermal stability and hydrolysis stability of the product polycarbonate, and is required to be 1000 ppm or less in order to have practical physical properties. Therefore, it is common to use an equimolar amount or more of the carbonic acid diester compound per 1 mol of the aromatic dihydroxy compound, and it is used in an amount of 1.01-1.30 mol, preferably 1.01-1.20 mol. Is desirable.
[0019]
Each of the stirring tanks (3) and (6) has a stirring blade attached to a vertical rotating shaft. However, the type of the blade is a uniform solution that achieves desired mixing and does not contain undissolved substances. If it can be prepared, there is no particular limitation. Moreover, in the case of illustration, although the 2nd stirring tank (6) connected with the 1st stirring tank (3) and the transfer piping (4) is made into a final stirring tank, if necessary in order to achieve desired mixing, Further, a stirring tank (6) connected by a transfer pipe (4) may be provided between the first stirring tank (3) and the second stirring tank (6). The mixing of both raw materials in the two or more stirring tanks (3) and (6) is preferably performed at a temperature not lower than the melting point of the carbonic acid diester and not higher than the melting point of the aromatic dihydroxy compound. For example, in the case of a mixture of DPC and BPA, a temperature of a melting point of DPC of 80 ° C. or higher and a melting point of BPA of 156 ° C. or lower is selected, but when BPA exceeds 150 ° C., it decomposes to produce a colored substance, 120 ° C. or lower Then, since the melt | dissolution rate to molten DPC falls, both raw materials are normally mixed at the temperature of 120 to 150 degreeC, Preferably the temperature is around 140 degreeC.
[0020]
However, it is necessary to use the transfer pipe (4) having no flow path constriction portion such as a control valve or a pipe having a different inner diameter. Moreover, it is necessary to transfer the raw material mixture from one stirring tank (3) to the next stirring tank (6) only by hydrostatic pressure. In order to execute this, the liquid level of the first stirring tank (3) is set to a level above the liquid level of the next stirring tank (6), and the transfer that connects the first stirring tank and the next stirring tank is performed. It is preferable that the highest level in the pipe (4) is at the same level as the liquid level of the one stirring tank (3). The liquid level of the stirring tank can be arbitrarily determined, but if the liquid level is too low, the dissolution time is shortened, and the possibility that unreacted raw material flows into the polymerization tank increases. On the other hand, if the liquid level is too high, the residence time of the stirring tank becomes longer, the raw material is colored, and the hue of the resulting polycarbonate is deteriorated. Usually, the liquid level is preferably set so that the residence time of each stirring tank is 0.5 to 2 hours, preferably 0.5 to 1.5 hours. The total residence time of the raw material mixture required to pass through all the stirring tanks (3), (6) and the transfer pipe (4) is within 300 minutes, preferably within 240 minutes, particularly preferably within 180 minutes. It is preferable.
When the liquid level of one agitation tank (3) exceeds the highest level in the transfer pipe (4), the raw material mixture in the agitation tank passes through the transfer pipe (4) to the next agitation tank (6). Be transported. The pipe diameter of the transfer pipe is preferably such that the flow rate is 0.06 m / sec or more because if the pipe diameter is too large, the residence time becomes long.
[0021]
<Polycondensation reaction>
Transesterification catalyst
When producing an aromatic polycarbonate by a transesterification method, a transesterification catalyst is usually used. As the transesterification catalyst, alkali metal compounds and / or alkaline earth metal compounds are mainly used, and basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds are supplementarily used. It is also possible to use together. These catalysts may be used alone or in combination of two or more.
[0022]
The amount of the catalyst is usually 1 × 10 to 1 mol of the aromatic dihydroxy compound.^-8~ 1x10^-FiveUsed in the molar range. If the amount is less than this amount, the polymerization activity required for a long time to produce a polycarbonate having a predetermined molecular weight and terminal hydroxy group amount cannot be obtained. If the amount is more than this amount, the polymer hue deteriorates and foreign matter due to gel generation is generated. The amount tends to increase. In particular, when an alkali metal compound and / or an alkaline earth metal compound is used, the amount of these metals is 1 × 10.^-8~ 2x10^-6The molar range is preferred, 0.5 × 10^-7~ 1x10^-6A molar range is particularly preferred.
[0023]
Examples of the alkali metal compound include lithium, sodium, potassium, rubidium, cesium hydroxide, hydrogen carbonate, carbonate, acetate, hydrogen phosphate, and phenyl phosphate, stearic acid, Examples include organic acids such as benzoic acid, alcohols such as methanol and ethanol, organic alkali metal compounds such as salts with phenols such as carboxylic acid and bisphenol A, and the like. Examples of alkaline earth metal compounds include beryllium, calcium, magnesium, strontium, barium hydroxide, inorganic alkaline earth metal compounds such as hydrogen carbonate, carbonate, acetate, organic acids, alcohols, and phenols. And organic alkaline earth metal compounds such as salts thereof.
[0024]
Specific examples of basic boron compounds include tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, triethylphenylboron, tributyl. Hydride such as benzyl boron, tributyl phenyl boron, tetraphenyl boron, benzyl triphenyl boron, methyl triphenyl boron, butyl triphenyl boron, sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, barium salt, or Examples include strontium salts.
[0025]
Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, and quaternary phosphonium salts.
[0026]
Examples of the basic ammonium compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, Triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide Sid, butyl triphenyl ammonium hydroxide, and the like.
[0027]
Examples of the amine compound include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2 -Dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like.
[0028]
Aromatic polycarbonate
Aromatic polycarbonate is produced in a multistage process of two or more stages. In general, the reaction temperature is 140 to 320 ° C., the reaction time is 0.1 to 5 hours, the pressure is increased step by step from the normal pressure, and by-product monophenol compounds are continuously removed from the line, Perform polycondensation reaction. Finally, a polycondensation reaction is performed at a temperature of 250 to 320 ° C. under a reduced pressure of 267 Pa or less to increase the molecular weight to a viscosity average molecular weight of 10,000 to 100,000, preferably 12,000 to 40,000. If necessary, an inert gas such as nitrogen can be circulated. Moreover, in order to return the raw material compound accompanying the monophenol compound to the polymerization tank, a fractionation tower can be attached to the polymerization tank.
[0029]
The reaction method may be any of a batch method, a continuous method, and a combination of a batch method and a continuous method. The apparatus to be used may be any of a tank type, a tube type, or a tower type, for example, equipped with various stirring blades such as a Faudler blade, an anchor blade, a turbine blade, a double helical blade, and a Max blend blade. A vertical polymerization tank, a horizontal uniaxial polymerization tank, and / or a horizontal biaxial polymerization tank can be used.
[0030]
The reaction is preferably carried out under substantially oxygen-free conditions. For example, the raw material preparation tank, the polymerization tank, and the piping are replaced with an inert gas such as nitrogen gas before the start of operation. Usually, a molten mixture of an aromatic dihydroxy compound and a carbonic acid diester compound is supplied to a vertical polymerization tank. The catalyst may be directly supplied to the first polymerization tank through a line different from the raw material, or may be supplied in a state of being mixed with the raw material by a static mixer or the like in the pipe before entering the first polymerization tank. . Furthermore, you may add to the final stirring tank which prepares the raw material mixture supplied to a 1st polymerization tank. The advantage of adding the catalyst in the raw material adjusting tank is that the temperature is lower than that of the polymerization tank. In general, when BPA reaches 160 ° C. or higher, it decomposes to produce a colored substance. For this reason, when a catalyst is added at 140 ° C., BPA partially reacts with DPC and is stabilized against heat. Also, a certain period of time is required to disperse the catalyst in the raw material, which is advantageous for adding to the raw material preparation tank to increase the dispersion and reaction time. If necessary, a solvent for dissolving or suspending the catalyst is used. Preferable solvents include water, acetone, phenol and the like.
[0031]
It is preferable that the polymerization solution supply port is in the reaction vessel side wall liquid phase portion and the extraction port is in the reaction vessel bottom portion. In addition, the method of continuously extracting the reaction liquid from each tank is performed by a method suitable for the physical properties of the reaction liquid, such as a method using a drop, a method using a pressure difference, a method using a liquid feed pump such as a gear pump. Is preferred.
[0032]
Additive
When a catalyst such as an alkali metal compound is used as an additive used in the present invention, an acidic compound, particularly a sulfur-containing acidic compound, is added to the catalyst metal in order to neutralize the catalyst remaining in the polycarbonate. 0.5 to 10 equivalents, preferably 1 to 5 equivalents can be added. That is, 0.01 to 20 ppm is usually added, preferably 0.1 to 10 ppm, and more preferably 3 to 7 ppm.
[0033]
Examples of sulfur-containing acidic compounds are sulfonic acid, sulfinic acid or their ester derivatives, specifically p-toluenesulfonic acid, benzenesulfonic acid and dodecylbenzenesulfonic acid, their methyl, ethyl, butyl, Examples thereof include esters such as t-butyl, octyl, dodecyl, phenyl, benzyl, phenethyl, benzenesulfinic acid, toluenesulfinic acid, naphthalenesulfonic acid, and the like. Of these compounds, esters of p-toluenesulfonic acid or esters of benzenesulfonic acid are preferred, and two or more of these compounds may be used. Furthermore, it is preferable to use alkali metal salts of these compounds in combination with these compounds because the dispersibility is improved and the deactivation effect is enhanced. As an amount to be used in combination, it is preferable to use an alkali metal salt in an amount of about 0.3 to 3 times by weight with respect to the non-alkali metal salt.
[0034]
The sulfur-containing acidic compound can be added to the polycarbonate by any method. For example, sulfur-containing acidic compounds can be added or dispersed directly or diluted with a diluent and added to a molten or solid polycarbonate. Specifically, in the polycondensation reactor, in the transfer line from the reactor, it can be supplied and mixed in the extruder, and is usually supplied in the extruder. Further, after mixing with polycarbonate, other polymer pellets, flakes, powders or the like with a mixer or the like, the mixture can be supplied to an extruder and kneaded. Among these, it is preferable to add a stock solution of a sulfur-containing acidic compound to polycarbonate flakes, mix with a mixer or the like, and then add as a master batch. Furthermore, when adding, it is preferable to control the addition amount with high accuracy using a weight feeder or the like.
[0035]
In addition, when decompressing by venting with an extruder, or adding water, heat stabilizer, mold release agent, dye, pigment, UV absorber, antistatic agent, antifogging agent, organic / inorganic filler, etc. In some cases, these additions and treatments may be carried out simultaneously with the sulfur-containing acidic compound, but it is preferable to first add and knead the sulfur-containing acidic compound.
The extruder may be of any type as long as it has a degassing function. Specific examples include a vent type single-screw or multi-screw extruder, but a meshing twin-screw extruder is particularly preferable, and the rotational direction may be the same direction or different direction. The number of vents is not limited, but usually a multistage vent of 2 to 10 stages is used.
[0036]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In addition, the analysis of the obtained aromatic polycarbonate was performed with the following measuring method.
[0037]
(1) Viscosity average molecular weight (Mv)
The intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured using an Ubbelohde viscometer, and the viscosity average molecular weight (Mv) was determined from the following formula.
[Η] = 1.23 × 10^-Four× (Mv)^0.83
[0038]
(2) Hue
After drying the polycarbonate at 120 ° C. for 6 hours or more under a nitrogen atmosphere, the polycarbonate temperature was 280 ° C. and the mold temperature was 90 ° C. using a J-100SS-2 injection molding machine manufactured by Nippon Steel Works. The three-stimulus value XYZ, which is the absolute value of the color, was measured with a color tester SC-1-CH manufactured by Suga Test Instruments Co., Ltd. for an injection molded product having a thickness of 3 mm and a side of 100 mm square. Was used to calculate the YI value, which is an index of yellowness.
YI = (100 / Y) × (1.28X−1.06Z)
It shows that it colors, so that this YI value is large.
[0039]
Example 1
Raw material solution preparation
In the flow sheet shown in FIG. 1, BPA (supply rate 44.9 kg / h) and DPC (supply rate 44.7 kg / h) were adjusted to 140 ° C. through the raw material introduction pipes (1) and (2) in a nitrogen gas atmosphere. The internal volume is set to 0.2m^Three And continuously introduced into the first stirring tank (3) equipped with an anchor type stirring blade. The liquid level of the stirring tank (3) is the same height as the highest position in the transfer pipe (4) (the inner volume of the stirring tank (3) is 0.13 m).^Three The equivalent volume of the raw material mixture is 0.2 m.^Three In the second stirring tank (6) equipped with an anchor type stirring blade, it is transferred at a speed of 0.14 m / sec through a transfer pipe (4) having an inner diameter of 17.5 mm connecting both stirring tanks. The total residence time of the raw material mixture required to pass through the stirring tanks (3) and (6) and the transfer pipe (4) was 160 minutes. At the same time when the raw material mixture was transferred to the second stirring tank (6), 0.16% aqueous cesium carbonate as a catalyst was added to 0.5 × 10 5 per 1 mol of BPA.^-6Continuous introduction into the stirring tank (6) was started from the catalyst introduction pipe (5) at a molar flow rate.
[0040]
Polycondensation reaction
One hour after the start of transfer to the stirring tank (6), the raw material solution prepared in the same tank and completely dissolved in BPA and not containing undissolved substances was supplied to the normal pressure via the supply pipes (7) and (9). The mixture was continuously supplied to a first vertical stirring polymerization tank controlled at 210 ° C. in a nitrogen atmosphere. The liquid level was kept constant while controlling the valve opening degree provided in the polymer discharge line at the bottom of the tank so that the average residence time in the polymerization tank was 60 minutes.
[0041]
The polymerization liquid discharged from the bottom of the first polymerization tank was continuously continuously supplied to the second, third and fourth vertical polymerization tanks and the fifth horizontal stirring polymerization tank. During the reaction, the liquid level was controlled so that the average residence time of each tank was 60 minutes, and at the same time, by-product phenol was distilled off. In these polymerization tanks, the second polymerization tank (210 ° C., 13300 Pa), the third polymerization tank (240 ° C., 1995 Pa), the fourth polymerization tank (260 ° C., 67 Pa), and the fifth polymerization tank (265 ° C., 67 Pa), respectively. Then, the polymerization conditions were set so that the high temperature, high vacuum, and low stirring speed were achieved with the progress of the reaction. The production rate of the aromatic polycarbonate is 50 kg / h. The molecular weight of the obtained polycarbonate was 15500.
[0042]
This polymer was introduced into a twin-screw extruder (Kobe Steel Co., Ltd., 46 mmφ meshing screw, in the same direction) in a molten state, and 5 ppm of p-toluenesulfonate was added, followed by pelletization. The hue of the obtained polymer was 1.6.
[0043]
Comparative Example 1 (Single stirring tank, liquid level control by control valve)
The same operation as in Example 1 was performed except that the flow sheet shown in FIG. 2 was used instead of the flow sheet shown in FIG. Immediately after the start of operation, undissolved BPA was clogged in the control valve 11, and the operation could not be continued.
[0044]
Comparative Example 2 (The first stirring tank is controlled by the control valve)
The same operation as in Example 1 was performed except that the flow sheet shown in FIG. 3 was used instead of the flow sheet shown in FIG. Immediately after the start of operation, as in Comparative Example 1, undissolved BPA was clogged in the control valve 11, making it impossible to continue the operation.
[0045]
【The invention's effect】
According to the present invention, it is possible to obtain a transesterification aromatic polycarbonate excellent in hue without clogging of a transfer pipe.
[Brief description of the drawings]
1 is a flow sheet diagram showing preparation of a raw material solution of Example 1. FIG.
2 is a flow sheet diagram showing the preparation of a raw material solution of Comparative Example 1. FIG.
3 is a flow sheet diagram showing the preparation of a raw material solution of Comparative Example 2. FIG.
[Explanation of symbols]
1, 2 Raw material introduction pipe
3 First stirring tank
4 Transfer piping
5 Catalyst introduction pipe
6 Second stirring tank
7, 9 Supply piping to the polymerization system
8 Pump
10 Liquid level gauge
11 Control valve

Claims (5)

In the method for producing an aromatic polycarbonate by polycondensation reaction between an aromatic dihydroxy compound and a carbonic acid diester in the presence of a transesterification reaction catalyst, the raw material, the aromatic dihydroxy compound and the carbonic acid diester, are connected by a transfer pipe. Using a stirring tank, continuously mixing to prepare a uniform solution containing no undissolved material, and when supplying to the polymerization system, use a transfer pipe without a channel constriction, and A method for producing an aromatic polycarbonate, comprising transferring a raw material mixture in the stirring tank to the next stirring tank only by hydrostatic pressure. 2. The method for producing an aromatic polycarbonate according to claim 1, wherein the mixing is performed at a temperature not lower than the melting point of the carbonic acid diester and not higher than the melting point of the aromatic dihydroxy compound. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the aromatic hydroxy compound is bisphenol A and the carbonic acid diester is diphenyl carbonate. The method for producing an aromatic polycarbonate according to any one of claims 1 to 3, wherein a total residence time of the raw material mixture required for passing through the stirring tank and the transfer pipe is set to be within 300 minutes. The method for producing an aromatic polycarbonate according to any one of claims 1 to 4, wherein a flow rate of the raw material mixture passing through the transfer pipe is 0.06 m / sec or more.

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