JP2004091695A - Method for manufacturing aromatic polycarbonate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient method for manufacturing a high-molecular weight aromatic polycarbonate having a good color hue by the solid polymerization method in an inert gas flow. <P>SOLUTION: In the method for manufacturing the aromatic polycarbonate having a viscosity-average molecular weight of 13,000-100,000 by the solid polymerization of a crystalline aromatic polycarbonate prepolymer in the inert gas flow, the inert gas containing a reaction by-product and/or a raw material discharged from a solid polymerization reactor is fed together with an oxygen-containing gas to an oxidation catalyst bed to decompose the reaction by-product and/or the raw material and subsequently the inert gas is re-circulated to the solid polymerization reactor. <P>COPYRIGHT: (C)2004,JPO

Description

【００３０】
［上記式（１）中、Ｒ_１、Ｒ_２、Ｒ_３およびＲ_４は、それぞれ独立に水素原子、ハロゲン原子、炭素数１〜１０のアルキル基、炭素数６〜２０のアリール基または炭素数７〜２０のアラルキル基であり、Ｗは単結合、炭素数１〜２０のアルキレン基、炭素数２〜２０のアルキリデン基、炭素数３〜１５のシクロアルキリデン基、炭素数３〜１５のシクロアルキレン基、酸素原子、硫黄原子、スルホキシド基又はスルホン基である。］
で表される芳香族ポリカーボネートプレポリマーである。上記式（１）中、Ｒ_１、Ｒ_２、Ｒ_３およびＲ_４は具体的には水素原子；フッ素原子、塩素原子、臭素原子等のハロゲン原子；メチル基、エチル基、プロピル基、ブチル基、ヘキシル基等の炭素数１〜１０のアルキル基；フェニル基、ナフチル基等の炭素数６〜２０のアリール基；ベンジル基等の炭素数７〜２０のアラルキル基等が挙げられる。Ｗは具体的には単結合；メチレン基、エチレン基、プロピレン基、ブチレン基等の炭素数１〜２０のアルキレン基；エチリデン基、プロピリデン基、ブチリデン基等の炭素数２〜２０のアルキリデン基；１，３−シクロペンチレン基、１，４−シクロヘキシレン基等の炭素数３〜１５のシクロアルキレン基；シクロペンチリデン基、シクロヘキシリデン基等の炭素数３〜１５のシクロアルキリデン基；エーテル基、スルホキシド基、スルフィド基、スルホン基などが挙げられる。また本発明の効果に影響がない範囲内（例えば３０モル％以下）で他の繰り返し単位からなる芳香族ポリカーボネートを共重合してもよい。
【００３１】
なかでもより好ましくは主に下記式（２）
【００３２】
【化２】

【００３３】
で表される繰り返し単位からなる芳香族ポリカーボネートであることである。また「主に」とは上記式で表される繰り返し単位が７０モル％であることを指す。このような結晶性芳香族ポリカーボネートプレポリマーは芳香族ジヒドロキシ化合物とカーボネート結合性化合物を原料として従来公知の手法にて製造することができる。具体的には芳香族ジヒドロキシ化合物と炭酸ジエスエテルを原料とする溶融重合法、芳香族ジヒドロキシ化合物とホスゲンなどのハロゲン化カルボニル化合物を原料とする界面重合法が挙げられる。より好ましくは溶融重合法により製造することである。
【００３４】
さらに本発明の対象とする結晶性芳香族ポリカーボネートプレポリマーの原料として使用する芳香族ジヒドロキシ化合物、炭酸ジエステルおよび重縮合触媒等についてより好ましい態様を以下に詳細に説明する。
【００３５】
該芳香族ジヒドロキシ化合物としては、具体的にはビス（４−ヒドロキシフェニル）メタン、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−メチルフェニル）プロパン、４，４−ビス（４−ヒドロキシフェニル）ヘプタン、２，２−ビス（４−ヒドロキシ−３，５−ジクロロフェニル）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、ビス（４−ヒドロキシフェニル）オキサイド、ビス（３，５−ジクロロ−４−ヒドロキシフェニル）オキサイド、ｐ，ｐ’−ジヒドロキシジフェニル、３，３’−ジクロロ−４，４’−ジヒドロキシジフェニル、ビス（ヒドロキシフェニル）スルホン、ビス（４−ヒドロキシフェニル）スルフィド、ビス（４−ヒドロキシフェニル）スルホキシド等が挙げられるが、特に２，２−ビス（４−ヒドロキシフェニル）プロパンが好ましい。
【００３６】
また本発明においては本発明の効果に影響がない範囲内（例えば３０モル％以下）で他の繰り返し単位からなる芳香族ポリカーボネートを共重合することができる。その共重合する芳香族ジヒドロキシ化合物としてはレゾルシノール、ハイドロキノン、１，４−ジヒドロキシ−２，５−ジクロロベンゼン、１，４−ジヒドロキシ−３−メチルベンゼンが挙げられる。
【００３７】
また該炭酸ジエステルとしては、具体的にはジフェニルカーボネート、ジナフチルカーボネート、ビス（ジフェニル）カーボネートなどが用いられる。これらのうち、ジフェニルカーボネートが、反応性、得られる樹脂の着色に対する安定性、更にはコストの点からも好ましい。すなわち芳香族ジヒドロキシ化合物として２，２−ビス（４−ヒドロキシフェニル）プロパンを、炭酸ジエステルとしてジフェニルカーボネートを用いて溶融重合法にて結晶性芳香族ポリカーボネートプレポリマーを製造することがより好ましい。
【００３８】
重合速度を速めるために重縮合触媒を用いることもできる。該重縮合触媒としては、水酸化ナトリウム若しくは水酸化カリウムなどのアルカリ金属やアルカリ土類金属の水酸化物類；ホウ素、アルミニウムの水酸化物のアルカリ金属塩、アルカリ土類金属塩若しくは第４級オニウム塩類；アルカリ金属若しくはアルカリ土類金属のアルコキシド類；アルカリ金属若しくはアルカリ土類金属の有機酸塩類；アルカリ金属若しくはアルカリ土類金属の無機酸塩類；亜鉛化合物類；ホウ素化合物類；ケイ素化合物類；ゲルマニウム化合物類；有機スズ化合物類；鉛化合物類；アルカリ金属若しくはアルカリ土類金属以外のオニウム塩類；アンチモン化合物類；マンガン化合物類；チタン化合物類；およびジルコニウム化合物類などの通常エステル化反応、エステル交換反応に使用される重縮合触媒を用いることができるが、これらに限定されるものではない。重縮合触媒を用いる場合これらのうち１種だけを用いてもよいし、２種以上を組み合わせて用いてもよい。これらの重縮合触媒の使用量は原料の芳香族ジヒドロキシ化合物１モルに対し１０^−８〜１０^−３モル、好ましくは１０^−７〜５×１０^−４モル、更に好ましくは５×１０^−７〜２×１０^−４モルの範囲で選ばれる。
【００３９】
本発明の固相重合の出発原料である結晶性芳香族ポリカーボネートプレポリマーは、低分子量の非晶性芳香族ポリカーボネートプレポリマーを結晶化させることにより得られる。またその低分子量の非晶性芳香族ポリカーボネートプレポリマーの製造には、既に公知の種々の重合法を採用することができるが、先述のように溶融重合法が好ましく使用できる。さらに低分子量の非晶性芳香族ポリカーボネートプレポリマーを結晶化させる方法としては、公知の溶媒処理法、加熱結晶法、溶融状態の非晶性芳香族ポリカーボネートプレポリマーに剪弾力を付加する剪断結晶化法などを挙げることができる。本発明において用いられる結晶化の方法は特に制限されず、これらの結晶化方法を組み合わせることも可能である。
【００４０】
本発明においては、非晶性の（即ち実質的に結晶化していない）低分子量の芳香族ポリカーボネートプレポリマーの粘度平均分子量には３，０００から５０，０００、さらには５，２００から２２，０００がより好ましく使用できる。
【００４１】
本発明では、低分子量の非晶性芳香族ポリカーボネートプレポリマーをそのガラス転移温度（Ｔｇ）以上かつ結晶性芳香族ポリカーボネートプレポリマーの融点未満の温度範囲に保持して結晶化させることが好ましい。この温度が低分子量の非晶性芳香族ポリカーボネートプレポリマーのガラス転移温度（Ｔｇ）未満の温度では結晶化はほとんど進行せず、結晶性芳香族ポリカーボネートプレポリマーの融点以上の温度では結晶が融解してしまう。好ましい結晶化処理温度は（該低分子量の非晶性芳香族ポリカーボネートプレポリマーのガラス転移温度＋２０℃）以上かつ結晶性芳香族ポリカーボネートプレポリマーの融点未満の温度であり、より好ましくは（該低分子量の非晶性芳香族ポリカーボネートプレポリマーのガラス転移温度＋４０℃）以上かつ（結晶性芳香族ポリカーボネートプレポリマーの融点−５℃）以下の温度である。
【００４２】
また、結晶化を促進するために、特開２００１−１１１７１号公報に記載されたように、既に結晶化した芳香族ポリカーボネートを少量結晶核として使用してもよい。別の結晶化促進方法として、炭酸ジエステル、芳香族ジヒドロキシ化合物等を少量可塑剤として使用することもできる。
【００４３】
この結晶化に要する時間は、結晶化処理方法および低分子量の非晶性芳香族ポリカーボネートプレポリマーの分子量、ガラス転移温度（Ｔｇ）、低分子量の非晶性芳香族ポリカーボネートプレポリマーの量に依存する。
【００４４】
通常、こうした結晶化処理の前後または同時に造粒も実施することも好ましい。造粒方法としては、溶融状態のものを所定の大きさで、所定の温度の板状に落とし付着させる方法、ストランドカッター、液中カッター、ホットカッターなどを用いてペレット状に切断する方法、結晶化に使用する溶媒を用いた液中カッターを使用して結晶化と造粒を同時に行う方法、所定の大きさに固化した結晶化物を単に粉砕する方法、あらかじめ所定の大きさに粉砕し粉状にした結晶化物を圧縮造粒する方法等が採用される。
【００４５】
以上の方法で製造した結晶性芳香族ポリカーボネートプレポリマーは、固相状態のまま、該結晶性芳香族ポリカーボネートプレポリマーの融点以下の温度で、不活性ガス流通下にて固相重合され、粘度平均分子量は１３，０００から１００，０００で、色相が良く、ゲル成分も少ない成形性に優れた芳香族ポリカーボネートとなる。その結晶性芳香族ポリカーボネートの固相重合の方法は、低分子量の非晶性芳香族ポリカーボネートプレポリマーを結晶化させた後にこれを固相重合するプロセスであり、公知のプロセスである。例えば、特開２００１−１１１７１号公報に記載されている。さらに必要に応じて末端ヒドロキシ基の封鎖反応や触媒失活を行うことで、溶融粘度の安定化を行うことができ、それにより芳香族ポリカーボネートの成形時の熱安定性や耐久安定性を向上させる上で好ましい。
【００４６】
【発明の効果】
本発明によれば、不活性ガス流通下における固相重合法による芳香族ポリカーボネートの製造方法において、循環再使用する不活性ガス中に酸素を実質上存在させず、さらに、反応副生成物等の濃度を低くすることができるので、色相の良く、さらに高分子量の芳香族ポリカーボネートを効率よく製造することが可能である。
【００４７】
【実施例】
本発明の実施例を次に示す。ただし本発明はこれらの実施例によって限定されるものではない。
【００４８】
［分析方法］
１）不活性ガス中のフェノールの濃度
採取した不活性ガスとフェノールとの混合ガス中のフェノールをアセトニトリルに溶解させ、この溶液中のフェノール濃度をガスクロマトグラフィーで測定することにより求めた。本実施例では反応副生成物等の濃度に対応する。
【００４９】
２）粘度平均分子量
ジクロロメタン中、２０℃でウベローデ粘度計を用い固有粘度［η］を測定し、次式により粘度平均分子量Ｍを求めた。
［η］＝１．２３×１０^−４×Ｍ^０．８３
【００５０】
３）ガラス転移温度、融点
パーキンエルマーＤＳＣ７により、昇温速度２０℃／分で測定してガラス転移温度（Ｔｇ）、融点（Ｔｍ）を求めた。また、結晶融解エンタルピー（ΔＨ）は、結晶融解に対応するピーク部分の面積より算出した。
【００５１】
４）結晶化度
結晶化度は、ＤＳＣ測定によって得られたΔＨから１００％結晶化ポリカーボネートのΔＨをジャーナル・オブ・ポリマー・サイエンス；パートＢ：ポリマー・フィジックス（Ｊ．　Ｐｏｌｙｍ．　Ｓｃｉ．　：Ｐｏｌｙｍ．　Ｐｈｙｓ．）１９７９年第２５巻１５１１〜１５１７ページを参考にして１０９．８Ｊ／ｇとして計算した。
【００５２】
５）炭化水素濃度
水素炎イオン化検出法による全炭化水素濃度計を用いた。
【００５３】
６）水分濃度
近赤外吸収分光計を用いて測定した。
【００５４】
［参考例１］低分子量の非晶性芳香族ポリカーボネートプレポリマーの合成例攪拌槽、精留塔、コンデンサー、減圧装置を有する重合反応装置の攪拌槽に、２，２−ビス（４−ヒドロキシフェニル）プロパンを２０００ｇ／ｈｒ、ジフェニルカーボネートを１９３３ｇ／ｈｒ、テトラメチルアンモニウムヒドロキシド７９ｍｇ／ｈｒおよびビスフェノールＡジナトリウム塩を１．２ｍｇ／ｈｒの割合で連続的に供給し、温度２４０℃、反応圧力１．３ｋＰａ、平均滞留時間２時間で、反応副生成物のフェノールを攪拌槽から留出させながら反応を行った。反応で得られた生成物は２３４５ｇ／ｈｒの割合で連続的に攪拌槽から抜き出した。この時点で、得られた低分子量の非晶性芳香族ポリカーボネートの粘度平均分子量は５，６００、ガラス転移温度は１１６℃であった。
【００５５】
［参考例２］結晶性芳香族ポリカーボネートプレポリマーの合成例
上記の参考例１で得られた非晶性の低分子量芳香族ポリカーボネートの一部を取り出し、１８０℃、４時間窒素ガス雰囲気下で静置させ熱処理をした。なお、この熱処理１時間ではほとんど結晶化は進んでいなかったが、さらに４時間の熱処理で結晶化度２５．４％のものが得られた。得られた結晶性芳香族ポリカーボネートプレポリマーの粘度平均分子量は５，６５０、融点は２２０℃、ΔＨは２７．９Ｊ／ｇであった。これを粉砕した後、目開き１ｍｍと２ｍｍのふるいを用い分級し、粒径１ｍｍから２ｍｍの粉末とした。
【００５６】
［実施例１］
上記の参考例２で得られた結晶性芳香族ポリカーボネートプレポリマーを２０００ｇ／ｈｒで連続的に容量１００Ｌのジャケット付ホッパー型固相重合反応器に供給した。そして、固相重合反応器ジャケット内熱媒体の反応温度２００℃、反応圧力は常圧で窒素ガスを固相重合反応器に流通させながら固相重合反応を行った。また、この時、反応で得られた芳香族ポリカーボネートは１９３６ｇ／ｈｒの割合で連続的に固相重合反応器から抜き出した。また、窒素ガスを２００℃に加熱し、５０ＮＬ／ｍｉｎの割合で連続的に固相重合反応器の下部から上部に流通させた。
【００５７】
反応に使用した窒素ガスは反応副生物であるフェノールを同伴し固相重合反応器から排出させ、酸素ガスと混合し、加熱器で２７５℃まで昇温させた後、多孔性シリカ担持パラジウム触媒を充填した酸化触媒床に供給させた。
【００５８】
酸化触媒床における温度は２７５℃とした。また、窒素ガスに混合する酸素ガス供給量は、酸化触媒床出側のフェノール濃度が１００ｐｐｍになるよう制御した。酸素ガス供給量は１．７６ＮＬ／ｍｉｎだった。尚、フェノール濃度は、全炭化水素測定計によりオンラインで測定した炭化水素濃度から換算した。
【００５９】
酸化触媒床により反応副生成物等の濃度が低減された窒素ガスは、冷却した後、水分離装置であるモレキュラーシーブ充填カラムに供給させた。その結果、水分離装置の出側の不活性ガス中の水分濃度は１０４ｐｐｍであった。上記方法で得られた芳香族ポリカーボネートの粘度平均分子量は２３，９００であった。
【００６０】
［比較例１］
反応で使用した窒素ガス中からの反応副生成物等の除去において、酸化触媒床を使わずにサーフェースコンデンサーを用いること以外は実施例１と同様に実施した。窒素ガス中の反応副生成物のフェノールがサーフェースコンデンサー中で凝固し装置内を閉塞させないようにするため、サーフェースコンデンサー出側の窒素ガス温度を５０℃とした。その結果、窒素ガス中のフェノール濃度は１．１ｗｔ％であった。この窒素ガスを固相重合反応器へ循環した結果、芳香族ポリカーボネートの粘度平均分子量は１０，３００であり、充分な分子量の芳香族ポリカーボネートを得ることは出来なかった。
【図面の簡単な説明】
【図１】本発明の芳香族ポリカーボネートの固相重合法による製造プロセスの一例の概略を示したものである。
【符号の説明】
１：固相重合反応器
２：酸化触媒床
３：水分離装置
４：ガス循環ポンプ
５：ヒーター
６：原料供給配管
７：反応物吐出配管
８：酸素含有ガス供給配管[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an aromatic polycarbonate by solid-state polymerization, and more particularly to an inert gas obtained by decomposing a reaction by-product and / or a raw material in an inert gas discharged from a solid-state polymerization reactor. And a method for producing an aromatic polycarbonate.
[0002]
[Prior art]
In a method for producing an aromatic polycarbonate by a polycondensation reaction, it is necessary to remove by-products generated by the reaction from the reaction system. In such a case, generally, a method in which an aromatic polycarbonate prepolymer is subjected to a polymerization reaction in a molten state and the pressure inside the polymerization reactor is reduced by suction is most often used. However, in this method, a highly airtight polymerization reaction apparatus is required to maintain the inside of the reaction system at a high vacuum, and further, when the molecular weight of the aromatic polycarbonate becomes high, the melt viscosity becomes extremely high, so that a stirrer is provided. When a polymerization reactor is used, there is a problem that a large load is required in terms of manufacturing cost such as a large amount of stirring power is required.
[0003]
Further, instead of the above-described method in which the inside of the polymerization reactor is suctioned under reduced pressure, the polyaromatic polycarbonate prepolymer is subjected to a polycondensation reaction by a solid-phase polymerization method under the flow of an inert gas, and the by-product formed is not changed. A method of causing a polycondensation reaction under a weak vacuum or at atmospheric pressure by entraining it in an active gas and excluding it from the reaction system is well known (for example, see Patent Document 1).
[0004]
This method has the advantage that the polymerization reactor does not need to be maintained at a high vacuum and does not require stirring, but requires the use of a large amount of inert gas. In addition, if an attempt is made to recycle the inert gas in order to reduce the amount of the inert gas used, it is necessary to separate and remove reaction by-products and / or raw materials from the inert gas discharged from the solid-state polymerization reactor. There was a problem.
[0005]
To solve this problem, there is a method of separating and removing reaction by-products by using a condenser such as a surface condenser or an absorbing solution such as a scrubber.In the former, however, the reaction by-products are reduced below the equilibrium partial pressure at the condensation temperature. Since the concentration cannot be reduced, there is a problem that the reaction rate is reduced when the inert gas is recirculated.In the latter case, since the absorbing solution is used, the step of separating the absorbing solution and the reaction by-products is not performed. It is necessary and disadvantageous in terms of cost.
[0006]
On the other hand, in the solid-phase polymerization of an aromatic polyester resin, as a method of purifying an inert gas for washing, there is a method of purifying the same through a catalyst bed supported on an inert porous carrier and containing a mixture of Pt and Pd. (For example, see Patent Document 2).
[0007]
[Patent Document 1]
JP 2001-11171 A (pages 7-8)
[0008]
[Patent Document 2]
JP-A-8-252431 (page 2)
[0009]
[Problems to be solved by the invention]
The present invention overcomes the conventional problems of carrying out solid-state polymerization of a crystalline aromatic polycarbonate prepolymer as described above under an inert gas flow, and provides a method for producing an aromatic polycarbonate more efficiently. The purpose is to:
[0010]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on a method for producing a crystalline aromatic polycarbonate prepolymer by a polycondensation reaction by a solid-phase polymerization method under an inert gas flow, and as a result, the inert gas discharged from the solid-state polymerization reactor To an aromatic polycarbonate by an efficient and simplified method by treating the same with a specific method.
[0011]
That is, the present invention provides a method for producing an aromatic polycarbonate having a viscosity average molecular weight of 13,000 to 100,000 by solid-phase polymerization of a crystalline aromatic polycarbonate prepolymer under an inert gas flow. An inert gas containing the discharged reaction by-products and / or raw materials is supplied to an oxidation catalyst bed together with an oxygen-containing gas to decompose the reaction by-products and / or raw materials. This is a method for producing an aromatic polycarbonate, which is characterized by being recycled to a solid-state polymerization reactor.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a flow of the process for producing an aromatic polycarbonate by the production method of the present invention, in particular, a flow detailing an inert gas circulation process using an oxidation catalyst bed, which is a feature of the present invention.
[0013]
It is to be noted that this drawing merely shows one embodiment of the present invention, and it goes without saying that other embodiments whose design is appropriately changed are also included in the scope of the present invention. For example, in addition to the hopper type reactor shown in FIG. 1, solid phase polymerization reactors such as fluidized bed type reactors, tumbler type reactors, conduction type channel type agitating reactors, etc. A reactor capable of performing a polymerization reaction in the above is included in the category of the present invention. The solid-state polymerization reaction can be applied to the present invention either in a batch system (batch system) or in a continuous system. It is not essential to apply a step of decomposing reaction by-products and / or raw materials (hereinafter abbreviated as reaction by-products and the like) that are part of the present invention to all the steps of What is necessary is just to be used in a part of polycarbonate production stage.
[0014]
The production process according to the solid-state polymerization method of the present invention mainly comprises a solid-state polymerization reactor 1, an oxidation catalyst bed 2, and a water separation device 3. The water separator 3 is preferably installed during the manufacturing process, but need not be provided. In the case of the solid-state polymerization method, it is necessary to use a crystalline aromatic polycarbonate prepolymer that is at least partially crystallized (hereinafter simply referred to as “crystalline aromatic polycarbonate prepolymer” in the present invention) as a raw material. The viscosity average molecular weight of the crystalline aromatic polycarbonate prepolymer is not particularly limited, but is preferably from 3,000 to 50,000, more preferably from 5,200 to 22,000.
[0015]
The crystallinity of the crystalline aromatic polycarbonate prepolymer is preferably from 10% to 70%, and more preferably from 20% to 50%. As a method of measuring the degree of crystallinity, an X-ray diffraction method, a method using ΔH (crystal melting enthalpy) obtained by DSC measurement as described later, and the like can be mentioned. The crystalline aromatic polycarbonate prepolymer, which is a raw material for solid-phase polymerization, is supplied from a raw material supply pipe 6 to the solid-state polymerization reactor 1 continuously or batchwise. The solid-state polymerization reaction temperature (the temperature inside the solid-state polymerization reactor) is (the glass transition temperature of the amorphous aromatic polycarbonate prepolymer + 20 ° C. or more) and (the melting point of the crystalline aromatic polycarbonate prepolymer−5 ° C.). Or less), and more preferably (the glass transition temperature of the amorphous aromatic polycarbonate prepolymer + 30 ° C. or higher) and (the melting point of the crystalline aromatic polycarbonate prepolymer −10 ° C. or lower). At a temperature less than (the glass transition temperature of the amorphous aromatic polycarbonate prepolymer + 20 ° C.), the reaction does not proceed smoothly, and at a temperature exceeding (the melting point of the crystalline aromatic polycarbonate prepolymer−5 ° C.), Is melted, and it is difficult to maintain the solid phase of the crystalline aromatic polycarbonate prepolymer.
[0016]
When the crystalline aromatic polycarbonate prepolymer, which is a raw material, is continuously supplied to the solid-state polymerization reactor 1, the reaction mixture having undergone a certain degree of polycondensation reaction is continuously or batchwise withdrawn from the reactant discharge pipe 7.
[0017]
The inert gas circulated in the solid-state polymerization reactor 1 is circulated through the oxidation catalyst bed 2 and the water separator 3 by the gas circulation pump 4 in the solid-state polymerization reactor. Further, the inert gas can be newly replenished to the circulation system of the solid-state polymerization reaction device as needed. The inert gas is heated by the heater 5 and circulated in the solid-state polymerization reactor. The temperature of the heated inert gas is preferably the same as the solid-state polymerization reaction temperature. Preferred examples of the inert gas include nitrogen, helium, neon, argon, and carbon dioxide, with nitrogen being more preferred.
[0018]
The reaction pressure (pressure inside the solid-state polymerization reactor) is preferably 15 to 1000 kPa, more preferably 90 to 500 kPa, and still more preferably 90 to take advantage of the feature that solid phase polymerization proceeds while passing an inert gas. ~ 200 kPa is desirable. At a reaction pressure of less than 15 kPa, a high vacuum is generated and a large-scale apparatus for maintaining the high vacuum is required. At a reaction pressure higher than 1000 kPa, a load is applied to the gas circulation pump 4 for flowing an inert gas such as a compressor or a blower, which is not preferable.
[0019]
In the case of a batch type, the flow rate of the inert gas to be circulated in the solid-state polymerization reactor is preferably 1 to 100 NL / min per 1 kg of the charged amount of the crystalline aromatic polycarbonate prepolymer in the solid-state polymerization reactor. And more preferably 10 to 50 NL / min. In the case of the continuous type, the supply amount of the crystalline aromatic polycarbonate into the solid-state polymerization reactor is 1 kg / min, preferably 10 to 200 NL / min, and more preferably 20 to 100 NL / min. In the case of the batch type, if the flow rate is less than 1 NL / min, the effect of the inert gas circulation is too small and the reaction rate is too slow. There is the danger that it will become huge and impractical.
[0020]
The inert gas discharged from the solid-state polymerization reactor is led to the oxidation catalyst bed together with reaction by-products and the like. An oxygen-containing gas is also supplied from the oxygen-containing gas supply pipe 8 to the oxidation catalyst bed in order to oxidize and decompose reaction by-products and the like in the inert gas into carbon dioxide and water. Here, the oxygen-containing gas is a component that contains oxygen in a concentration sufficient to decompose reaction by-products and the like when supplied to the oxidation catalyst bed and that inhibits the oxidative decomposition reaction and solid-state polymerization reaction in the oxidation catalyst bed. There is no particular limitation as long as the gas does not contain any component that adversely affects the quality of the aromatic polycarbonate. Preferably, it is a gas containing 10 mol% or more of oxygen.
[0021]
In the present invention, it is preferable that a total hydrocarbon concentration meter be installed in order to measure the concentration of reaction by-products and the like in the inert gas. The concentration of the reaction by-products and the like in the inert gas can be obtained by converting from the hydrocarbon concentration measured by a total hydrocarbon concentration meter. The total hydrocarbon concentration meter to be used is not particularly limited as long as it can continuously measure the amount of hydrocarbons in the inert gas, but a flame flame ionization detection type is preferable. Further, the position where the total hydrocarbon concentration meter is installed is more preferably on the outlet side of the oxidation catalyst bed.
[0022]
In the oxidative decomposition of reaction by-products and the like in the oxidation catalyst bed, the stoichiometry in the oxidation reaction between the reaction by-products and the like in the inert gas on the inlet side of the oxidation catalyst bed and the oxygen in the oxygen-containing gas to be supplied. It is carried out with a stoichiometrically lower amount of oxygen. Therefore, the inert gas at the outlet side of the oxidation catalyst bed contains substantially no oxygen.
[0023]
The concentration of reaction by-products and / or raw materials in the inert gas at the outlet of the oxidation catalyst bed to be recycled to the solid-state polymerization reactor is preferably from 10 to 5000 ppm, more preferably from 10 to 1000 ppm, and still more preferably from 10 to 1000 ppm. 100 ppm. As described above, the concentration of the reaction by-products and the like in the inert gas can be adjusted to this range by, for example, controlling the flow rate of the oxygen-containing gas supplied to the oxidation catalyst bed. When the concentration is lower than 10 ppm, it becomes difficult to control the supply of the oxygen-containing gas, so that the supplied oxygen tends to be excessive, which causes coloring of the aromatic polycarbonate to be produced, and at a concentration higher than 5000 ppm. In addition, since the amount of reaction by-products and the like in the inert gas is too high, a sufficient solid-state polymerization reaction rate cannot be obtained when the inert gas is recycled to the solid-state polymerization reactor, which is not preferable.
[0024]
As the catalyst used in the oxidation catalyst bed, for example, a solid catalyst in which at least one metal element selected from the group consisting of platinum, palladium and nickel, a salt thereof, or a complex thereof is supported on a porous carrier is preferable. Examples of the porous carrier include alumina, silica, activated carbon, and diatomaceous earth.
[0025]
The oxidative decomposition temperature in the oxidation catalyst bed depends on the type of the catalyst used, but is preferably from 150 to 450C, more preferably from 250 to 350C. If the temperature is lower than 150 ° C., the oxidation reaction is not sufficiently promoted. If the temperature is higher than 450 ° C., reaction by-products and the like may be decomposed into compounds other than carbon dioxide and water, and the catalyst may be poisoned. Not preferred.
[0026]
It is preferable that the inert gas in which the concentration of reaction by-products and the like is reduced in the oxidation catalyst bed be supplied to the water separation device 3. In the water separation device, water generated by an oxidative decomposition reaction such as a reaction by-product in the oxidation catalyst bed is separated and removed from the inert gas. The water separation device is not particularly limited as long as it can separate water from the inert gas, but a water adsorption device using a water adsorbent is preferably used. Examples of the water adsorbent include molecular sieve, activated alumina, silica gel and the like.
[0027]
The inert gas whose water content has been reduced by the water separator is recycled to the solid-state polymerization reactor.
[0028]
In the present invention, a preferred crystalline aromatic polycarbonate prepolymer is represented by the following formula (1)
[0029]
Embedded image

[0030]
[In the above formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms or a carbon number. 7 to 20 are aralkyl groups, W is a single bond, an alkylene group having 1 to 20 carbon atoms, an alkylidene group having 2 to 20 carbon atoms, a cycloalkylidene group having 3 to 15 carbon atoms, and a cycloalkylene having 3 to 15 carbon atoms. Group, oxygen atom, sulfur atom, sulfoxide group or sulfone group. ]
Is an aromatic polycarbonate prepolymer represented by the formula: In the above formula (1), R ₁ , R ₂ , R ₃ and R ₄ are specifically a hydrogen atom; a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; a methyl group, an ethyl group, a propyl group and a butyl group. And an alkyl group having 1 to 10 carbon atoms such as a hexyl group; an aryl group having 6 to 20 carbon atoms such as a phenyl group and a naphthyl group; an aralkyl group having 7 to 20 carbon atoms such as a benzyl group. W is specifically a single bond; an alkylene group having 1 to 20 carbon atoms such as a methylene group, an ethylene group, a propylene group or a butylene group; an alkylidene group having 2 to 20 carbon atoms such as an ethylidene group, a propylidene group or a butylidene group; C3-C15 cycloalkylene groups such as 1,3-cyclopentylene group and 1,4-cyclohexylene group; C3-C15 cycloalkylidene groups such as cyclopentylidene group and cyclohexylidene group; ether Group, sulfoxide group, sulfide group, sulfone group and the like. An aromatic polycarbonate composed of other repeating units may be copolymerized within a range that does not affect the effects of the present invention (for example, 30 mol% or less).
[0031]
Of these, the following formula (2) is more preferable.
[0032]
Embedded image

[0033]
Is an aromatic polycarbonate comprising a repeating unit represented by the formula: “Mainly” means that the repeating unit represented by the above formula is 70 mol%. Such a crystalline aromatic polycarbonate prepolymer can be produced by a conventionally known method using an aromatic dihydroxy compound and a carbonate-binding compound as raw materials. Specific examples include a melt polymerization method using an aromatic dihydroxy compound and a diethyl ether as raw materials, and an interfacial polymerization method using an aromatic dihydroxy compound and a carbonyl halide compound such as phosgene as raw materials. More preferably, it is produced by a melt polymerization method.
[0034]
Further preferred embodiments of an aromatic dihydroxy compound, a carbonic acid diester, a polycondensation catalyst, and the like used as a raw material of the crystalline aromatic polycarbonate prepolymer of the present invention will be described in detail below.
[0035]
As the aromatic dihydroxy compound, specifically, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane , Bis (4-hydroxyphenyl) oxide, bis (3,5-dichloro-4-hydroxyphenyl) oxide, p, p'-dihydroxydiphenyl, 3,3'-dichloro-4,4'-dihydroxydiphenyl, bis ( (Hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) Although sulfoxide and the like, in particular 2,2-bis (4-hydroxyphenyl) propane is preferable.
[0036]
In the present invention, an aromatic polycarbonate comprising another repeating unit can be copolymerized within a range that does not affect the effects of the present invention (for example, 30 mol% or less). Examples of the aromatic dihydroxy compound to be copolymerized include resorcinol, hydroquinone, 1,4-dihydroxy-2,5-dichlorobenzene, and 1,4-dihydroxy-3-methylbenzene.
[0037]
As the carbonic acid diester, specifically, diphenyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate and the like are used. Of these, diphenyl carbonate is preferred from the viewpoints of reactivity, stability against coloring of the obtained resin, and cost. That is, it is more preferable to produce a crystalline aromatic polycarbonate prepolymer by a melt polymerization method using 2,2-bis (4-hydroxyphenyl) propane as an aromatic dihydroxy compound and diphenyl carbonate as a carbonic acid diester.
[0038]
A polycondensation catalyst may be used to increase the polymerization rate. Examples of the polycondensation catalyst include hydroxides of alkali metals and alkaline earth metals such as sodium hydroxide and potassium hydroxide; alkali metal salts, alkaline earth metal salts of hydroxides of boron and aluminum or quaternary metals. Onium salts; alkoxides of alkali metals or alkaline earth metals; organic acid salts of alkali metals or alkaline earth metals; inorganic acid salts of alkali metals or alkaline earth metals; zinc compounds; boron compounds; Normal esterification reaction and transesterification of germanium compounds; organotin compounds; lead compounds; onium salts other than alkali metals or alkaline earth metals; antimony compounds; manganese compounds; titanium compounds; and zirconium compounds. Use the polycondensation catalyst used for the reaction. Although it is not intended to be limited thereto. When a polycondensation catalyst is used, one of these may be used alone, or two or more may be used in combination. The amount of these polycondensation catalysts to be used is 10 ⁻⁸ to 10 ⁻³ mol, preferably 10 ^{−7 to} 5 × 10 ⁻⁴ mol, more preferably 5 × 10 ⁻⁷ to 1 mol of the aromatic dihydroxy compound as a raw material. It is selected in the range of 2 × 10 ⁻⁴ mol.
[0039]
The crystalline aromatic polycarbonate prepolymer which is a starting material for the solid phase polymerization of the present invention can be obtained by crystallizing a low molecular weight amorphous aromatic polycarbonate prepolymer. For the production of the low-molecular-weight amorphous aromatic polycarbonate prepolymer, various known polymerization methods can be adopted, but the melt polymerization method can be preferably used as described above. Known methods for crystallizing the low molecular weight amorphous aromatic polycarbonate prepolymer include a known solvent treatment method, a heating crystallization method, and a shear crystallization method in which a shear force is applied to the molten amorphous aromatic polycarbonate prepolymer. And the like. The crystallization method used in the present invention is not particularly limited, and these crystallization methods can be combined.
[0040]
In the present invention, the viscosity average molecular weight of the amorphous (ie, substantially non-crystallized) low molecular weight aromatic polycarbonate prepolymer is from 3,000 to 50,000, and even from 5,200 to 22,000. Can be more preferably used.
[0041]
In the present invention, it is preferable to crystallize the low molecular weight amorphous aromatic polycarbonate prepolymer in a temperature range of its glass transition temperature (Tg) or higher and lower than the melting point of the crystalline aromatic polycarbonate prepolymer. When this temperature is lower than the glass transition temperature (Tg) of the low molecular weight amorphous aromatic polycarbonate prepolymer, crystallization hardly progresses, and at a temperature higher than the melting point of the crystalline aromatic polycarbonate prepolymer, the crystals melt. Would. A preferable crystallization treatment temperature is a temperature equal to or higher than (the glass transition temperature of the low molecular weight amorphous aromatic polycarbonate prepolymer + 20 ° C.) and lower than the melting point of the crystalline aromatic polycarbonate prepolymer, and more preferably (the low molecular weight (Glass transition temperature of amorphous aromatic polycarbonate prepolymer + 40 ° C.) and (melting point of crystalline aromatic polycarbonate prepolymer −5 ° C.) or lower.
[0042]
In order to promote crystallization, a small amount of an already crystallized aromatic polycarbonate may be used as a crystal nucleus as described in JP-A-2001-11171. As another crystallization promoting method, a diester carbonate, an aromatic dihydroxy compound or the like can be used as a small amount of a plasticizer.
[0043]
The time required for the crystallization depends on the crystallization method, the molecular weight of the low molecular weight amorphous aromatic polycarbonate prepolymer, the glass transition temperature (Tg), and the amount of the low molecular weight amorphous aromatic polycarbonate prepolymer. .
[0044]
Usually, it is also preferable to carry out granulation before, after or simultaneously with such crystallization treatment. As a granulation method, a method of dropping a molten material into a plate of a predetermined size at a predetermined temperature and attaching it, a method of cutting into a pellet using a strand cutter, a submerged cutter, a hot cutter, etc., a crystal, Crystallization and granulation at the same time using a submerged cutter using the solvent used for crystallization, a method of simply pulverizing the crystallized solidified to a predetermined size, a method of pulverizing to a predetermined size in advance A method of compressing and granulating the crystallized material obtained as described above is employed.
[0045]
The crystalline aromatic polycarbonate prepolymer produced by the above method is solid-phase polymerized under an inert gas flow at a temperature equal to or lower than the melting point of the crystalline aromatic polycarbonate prepolymer in a solid state, and the viscosity average The aromatic polycarbonate has a molecular weight of 13,000 to 100,000, a good hue, a small amount of a gel component, and excellent moldability. The method of solid-phase polymerization of the crystalline aromatic polycarbonate is a process in which a low-molecular-weight amorphous aromatic polycarbonate prepolymer is crystallized and then solid-phase polymerized, which is a known process. For example, it is described in JP-A-2001-11171. Furthermore, by performing a blocking reaction of a terminal hydroxy group or deactivating a catalyst as necessary, it is possible to stabilize the melt viscosity, thereby improving the thermal stability and durability stability during molding of the aromatic polycarbonate. Preferred above.
[0046]
【The invention's effect】
According to the present invention, in a method for producing an aromatic polycarbonate by a solid phase polymerization method under the flow of an inert gas, substantially no oxygen is present in the inert gas to be recycled and reused, and further, such as reaction by-products Since the concentration can be reduced, it is possible to efficiently produce an aromatic polycarbonate having a good hue and a high molecular weight.
[0047]
【Example】
An embodiment of the present invention will be described below. However, the present invention is not limited by these examples.
[0048]
[Analysis method]
1) Phenol concentration in inert gas The phenol in the mixed gas of the collected inert gas and phenol was dissolved in acetonitrile, and the phenol concentration in this solution was determined by gas chromatography. In this embodiment, the concentration corresponds to the concentration of a reaction by-product or the like.
[0049]
2) Viscosity average molecular weight The intrinsic viscosity [η] was measured in dichloromethane at 20 ° C. using an Ubbelohde viscometer, and the viscosity average molecular weight M was determined by the following equation.
[Η] = 1.23 × 10 ⁻⁴ × M ^0.83
[0050]
3) Glass transition temperature and melting point The glass transition temperature (Tg) and the melting point (Tm) were determined by using a Perkin Elmer DSC7 at a heating rate of 20 ° C./min. The crystal melting enthalpy (ΔH) was calculated from the area of the peak corresponding to the crystal melting.
[0051]
4) Crystallinity The crystallinity was determined by converting ΔH of 100% crystallized polycarbonate from ΔH obtained by DSC measurement to Journal of Polymer Science; Part B: Polymer Physics (J. Polym. Sci .: Polym. Phys.) 1979, Vol. 25, pp. 1511-1517, and calculated as 109.8 J / g.
[0052]
5) Hydrocarbon concentration A total hydrocarbon concentration meter using a flame ionization detection method was used.
[0053]
6) Water concentration was measured using a near infrared absorption spectrometer.
[0054]
Reference Example 1 Synthesis Example of Low-Molecular-Weight Amorphous Aromatic Polycarbonate Prepolymer A 2,2-bis (4-hydroxyphenyl) was added to a stirring vessel of a polymerization reactor having a stirring vessel, a rectification tower, a condenser, and a decompression device. ) Propane was continuously supplied at a rate of 2000 g / hr, diphenyl carbonate at 1933 g / hr, tetramethylammonium hydroxide 79 mg / hr and bisphenol A disodium salt at a rate of 1.2 mg / hr, at a temperature of 240 ° C. and a reaction pressure of 1 The reaction was performed at a pressure of 0.3 kPa and an average residence time of 2 hours while distilling off phenol as a reaction by-product from the stirring tank. The product obtained by the reaction was continuously extracted from the stirring tank at a rate of 2345 g / hr. At this time, the obtained low-molecular-weight amorphous aromatic polycarbonate had a viscosity average molecular weight of 5,600 and a glass transition temperature of 116 ° C.
[0055]
Reference Example 2 Synthesis Example of Crystalline Aromatic Polycarbonate Prepolymer A part of the amorphous low molecular weight aromatic polycarbonate obtained in the above Reference Example 1 was taken out and allowed to stand at 180 ° C. for 4 hours under a nitrogen gas atmosphere. And heat-treated. Although crystallization hardly progressed in this heat treatment for 1 hour, a crystal having a crystallinity of 25.4% was obtained by further heat treatment for 4 hours. The resulting crystalline aromatic polycarbonate prepolymer had a viscosity average molecular weight of 5,650, a melting point of 220 ° C., and a ΔH of 27.9 J / g. After pulverizing this, it was classified using a sieve having openings of 1 mm and 2 mm to obtain a powder having a particle size of 1 mm to 2 mm.
[0056]
[Example 1]
The crystalline aromatic polycarbonate prepolymer obtained in Reference Example 2 was continuously supplied at a rate of 2000 g / hr to a hopper type solid phase polymerization reactor having a capacity of 100 L and a jacket. The solid-state polymerization reaction was carried out at a reaction temperature of 200 ° C. of the heat medium in the jacket of the solid-state polymerization reactor and at a normal reaction pressure while flowing nitrogen gas through the solid-state polymerization reactor. At this time, the aromatic polycarbonate obtained by the reaction was continuously extracted from the solid-state polymerization reactor at a rate of 1936 g / hr. Further, the nitrogen gas was heated to 200 ° C. and continuously flowed from the lower part to the upper part of the solid-state polymerization reactor at a rate of 50 NL / min.
[0057]
Nitrogen gas used for the reaction was discharged from the solid-state polymerization reactor accompanied by phenol as a reaction by-product, mixed with oxygen gas, and heated to 275 ° C. with a heater. It was fed to a packed oxidation catalyst bed.
[0058]
The temperature in the oxidation catalyst bed was 275 ° C. The supply amount of oxygen gas mixed with the nitrogen gas was controlled such that the phenol concentration on the oxidation catalyst bed exit side was 100 ppm. The supply amount of oxygen gas was 1.76 NL / min. The phenol concentration was converted from the hydrocarbon concentration measured online by a total hydrocarbon meter.
[0059]
The nitrogen gas whose concentration of reaction by-products and the like was reduced by the oxidation catalyst bed was cooled and then supplied to a molecular sieve packed column as a water separator. As a result, the water concentration in the inert gas at the outlet of the water separator was 104 ppm. The viscosity average molecular weight of the aromatic polycarbonate obtained by the above method was 23,900.
[0060]
[Comparative Example 1]
The removal of reaction by-products and the like from the nitrogen gas used in the reaction was carried out in the same manner as in Example 1 except that a surface condenser was used without using an oxidation catalyst bed. The temperature of the nitrogen gas at the outlet of the surface condenser was set to 50 ° C. in order to prevent the reaction product phenol in the nitrogen gas from solidifying in the surface condenser and blocking the inside of the apparatus. As a result, the phenol concentration in the nitrogen gas was 1.1 wt%. As a result of circulating this nitrogen gas to the solid state polymerization reactor, the viscosity average molecular weight of the aromatic polycarbonate was 10,300, and it was not possible to obtain an aromatic polycarbonate having a sufficient molecular weight.
[Brief description of the drawings]
FIG. 1 schematically shows an example of a production process of an aromatic polycarbonate of the present invention by a solid-state polymerization method.
[Explanation of symbols]
1: Solid-state polymerization reactor 2: Oxidation catalyst bed 3: Water separator 4: Gas circulation pump 5: Heater 6: Raw material supply pipe 7: Reactant discharge pipe 8: Oxygen-containing gas supply pipe

Claims (6)

In a method for producing an aromatic polycarbonate having a viscosity-average molecular weight of 13,000 to 100,000 by solid-phase polymerization of a crystalline aromatic polycarbonate prepolymer under an inert gas flow, a reaction auxiliary discharged from a solid-state polymerization reactor is produced. An inert gas containing a product and / or a raw material is supplied to an oxidation catalyst bed together with an oxygen-containing gas to decompose the reaction by-product and / or the raw material. A process for producing an aromatic polycarbonate. The production method according to claim 1, wherein the concentration of the reaction by-product and / or the raw material in the inert gas at the outlet of the oxidation catalyst bed to be recycled to the solid-state polymerization reactor is 10 ppm to 5000 ppm. The catalyst used in the oxidation catalyst bed is a solid catalyst in which at least one metal element selected from the group consisting of platinum, palladium and nickel, a salt thereof, or a complex thereof is supported on a porous carrier. The method according to 1. The method according to any one of claims 1 to 3, wherein the temperature of the oxidation catalyst bed is maintained at 150 to 450C. The production method according to any one of claims 1 to 4, wherein the inert gas on the outlet side of the oxidation catalyst bed is further supplied to a water separation device. The method according to any one of claims 1 to 5, wherein a total hydrocarbon concentration meter is used for measuring the concentration of a reaction by-product and / or a raw material in the inert gas.

Images