JP3746937B2 - Branched aromatic polycarbonate and method for producing the same - Google Patents

Description

（式中Ｇ及びＧ’は炭素数１〜１８の脂肪族基あるいは置換脂肪族基、又は芳香族基あるいは置換芳香族基であり、Ｇ及びＧ’は同一であっても異なっていてもよい。）
【００１０】
上記一般式（３）で表される炭酸ジエステルは、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等の炭酸ジアルキル化合物、ジフェニルカーボネート、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などが例示される。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であり、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は単独、あるいは２種以上を混合して使用してもよい。
【００１１】
本発明で用いられる芳香族ジヒドロキシ化合物は、下記式（４）で表される。式（４）
【化４】

【００１２】
（式中、Ｗは単結合、炭素数１〜８のアルキレン基、炭素数２〜８のアルキリデン基、炭素数５〜１５のシクロアルキレン基、炭素数５〜１５のシクロアルキリデン基又は、−Ｏ−，−Ｓ−，−ＣＯ−，−ＳＯ−，−ＳＯ₂−で示される２価の基からなる群から選ばれるものであり、Ｙ及びＺは、ハロゲン原子又は炭素数１〜６の炭化水素基であり、ｐ及びｑは０〜２の整数であり、ＹとＺ、ｐとｑは、いづれも、同一であっても異なっていてもよい。）
【００１３】
上記式（４）で表される芳香族ジヒドロキシ化合物としては、例えば、ビス（４−ヒドロキシジフェニル）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、２，２−ビス（４−ヒドロキシ−３−ｔ−ブチルフェニル）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−ジブロモフェニル）プロパン、４，４−ビス（４−ヒドロキシフェニル）ヘプタン、１，１−ビス（４−ヒドロキシフェニル）シクロヘキサン等のビスフェノール；４，４’−ジヒドロキシビフェニル、３，３’，５，５’−テトラメチル−４，４’−ジヒドロキシビフェニル等のビフェノール；ビス（４−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）エーテル、ビス（４−ヒドロキシフェニル）ケトン等が例示される。特に好ましくは、２，２−ビス（４−ヒドロキシフェニル）プロパン（以下、ビスフェノールＡと略す）があげられる。
これらの芳香族ジヒドロキシ化合物は単独、又は２種以上の混合物として用いられる。
【００１４】
本発明で芳香族ポリカーボネートを製造するに当り、炭酸ジエステルは、芳香族ジヒドロキシ化合物に対して過剰に用いられる。すなわち、芳香族ジヒドロキシ化合物に対して１．０１〜１．３０、好ましくは１．０２〜１．２０のモル比で用いられる。同一反応条件下では、このモル比が小さくなるほど反応速度が上昇し、ポリカーボネートの粘度平均分子量は大きくなる。また、この範囲でモル比が大きくなると、反応速度が低下し、粘度平均分子量は小さくなる。モル比が１．０１より小さくなると得られるポリカーボネートの末端ＯＨ基の量が多くなり、反応性は高くなるものの、熱安定性、耐加水分解性等が低下し、通常の使用には適当でなくなる。１．３０を超えると所望の分子量を持つ芳香族ポリカーボネートの生産が困難となる。
【００１５】
本発明においては、１分子中に１個以上のカルボキシル基、カルボン酸エステル基又はハロカルボニル基、ならびに２個以上のヒドロキシル基を有する化合物を特定量用いる。かかる化合物としては、例えば一般式（１）、（２）で示される化合物が使用できる。
【００１６】
式（１）
【化５】

【００１７】
（式中、Ａ環及びＢ環は、カルボキシル基、カルボン酸エステル基又はハロカルボニル基を有し、該エステル基はハロゲン原子で置換されていてもよい脂肪族もしくは芳香族基である。Ｘは単結合、炭素数１〜８のアルキレン基、炭素数２〜８のアルキリデン基、炭素数５〜１５のシクロアルキレン基、炭素数５〜１５のシクロアルキリデン基又は、−Ｏ−，−Ｓ−，−ＣＯ−，−ＳＯ−，−ＳＯ₂−で示される２価の基からなる群から選ばれる。）
【００１８】
式（２）
【化６】

【００１９】
（式中、Ｃ環、Ｄ環、Ｅ環、Ｆ環の少なくとも一つが、カルボキシル基、カルボン酸エステル基又はハロカルボニル基を有している。この時、エステル基はハロゲン原子で置換されていてもよい脂肪族もしくは芳香族基である。Ｘは単結合、炭素数１〜８のアルキレン基、炭素数２〜８のアルキリデン基、炭素数５〜１５のシクロアルキレン基、炭素数５〜１５のシクロアルキリデン基又は、−Ｏ−，−Ｓ−，−ＣＯ−，−ＳＯ−，−ＳＯ₂−で示される２価の基からなる群から選ばれる。）
【００２０】
このような化合物としては、具体的には、下記式の化合物が挙げられる。
【化７】

【００２１】
【化８】

【００２２】
【化９】

【００２３】
【化１０】

【００２４】
【化１１】

【００２５】
これらのうち、式（５）〜（１４）が特に好ましく用いられる。このような多官能化合物は、原料の芳香族ジヒドロキシ化合物に対して、０．０５〜０．８モル％、特に好ましくは０．１〜０．６モル％の量を添加して用いられる。また、これらは単独で、あるいは２種以上を混合して使用してもよい。
上記化合物を使用すれば、同等の分岐度を示す分岐ポリマーと比較すると、高荷重下での流動性が極めてよく、さらに色相や滞留熱安定性に優れている。これは、上記化合物が分岐剤として働き、化合物中のカルボキシル基、カルボン酸エステル基及び／又はハロカルボニル基が、重合によってエステル結合を生成するためと考えられる。
【００２６】
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。本発明で使用す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など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。
【００２７】
触媒量としては、芳香族ジヒドロキシ化合物１モルに対して、１×１０^-9〜１×１０^-3モルの範囲で用いられるが、特に物性面や取り扱いの面で良好なアルカリ金属化合物及び／又はアルカリ土類化合物では芳香族ジヒドロキシ化合物１モルに対して１×１０ー⁸〜１×１０ー⁵モル、好ましくは２×１０ー⁸〜８×１０ー⁶モルの範囲で用いられる。この量より少なければ、所定の分子量と末端ヒドロキシル基を有するポリカーボネートを製造するのに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、分岐が多くなる。
【００２８】
アルカリ金属化合物としては、例えば、水酸化ナトリウム、水酸化カリウム、水酸化リチウム、水酸化セシウム、炭酸水素ナトリウム、炭酸水素カリウム、炭酸水素リチウム、炭酸水素セシウム、炭酸ナトリウム、炭酸カリウム、炭酸リチウム、炭酸セシウム、酢酸ナトリウム、酢酸カリウム、酢酸リチウム、酢酸セシウム、ステアリン酸ナトリウム、ステアリン酸カリウム、ステアリン酸リチウム、ステアリン酸セシウム、水素化ホウ素ナトリウム、水素化ホウ素カリウム、水素化ホウ素リチウム、水素化ホウ素セシウム、フェニル化ホウ素ナトリウム、フェニル化ホウ素カリウム、フェニル化ホウ素リチウム、フェニル化ホウ素セシウム、安息香酸ナトリウム、安息香酸カリウム、安息香酸リチウム、安息香酸セシウム、リン酸水素２ナトリウム、リン酸水素２カリウム、リン酸水素２リチウム、リン酸水素２セシウム、フェニルリン酸２ナトリウム、フェニルリン酸２カリウム、フェニルリン酸２リチウム、フェニルリン酸２セシウム、ナトリウム，カリウム，リチウム，セシウムのアルコレート，フェノレート、ビスフェノールＡの２ナトリウム塩，２カリウム塩，２リチウム塩，２セシウム塩などが挙げられる。
【００２９】
また、アルカリ土類金属化合物としては、例えば、水酸化カルシウム、水酸化バリウム、水酸化マグネシウム、水酸化ストロンチウム、炭酸水素カルシウム、炭酸水素バリウム、炭酸水素マグネシウム、炭酸水素ストロンチウム、炭酸カルシウム、炭酸バリウム、炭酸マグネシウム、炭酸ストロンチウム、酢酸カルシウム、酢酸バリウム、酢酸マグネシウム、酢酸ストロンチウム、ステアリン酸カルシウム、ステアリン酸バリウム、ステアリン酸マグネシウム、ステアリン酸ストロンチウムなどが挙げられる。
【００３０】
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などの水酸化物が挙げられる。
【００３１】
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などが挙げられる。
【００３２】
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などが挙げられる。
【００３３】
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、アミノキノリンなどが挙げられる。
【００３４】
エステル交換反応は一般には二段階以上の多段工程で実施される。具体的には、第１段目の反応は、９．３×１０⁴〜１．３３×１０³Ｐａの減圧下に１２０〜２６０℃、好ましくは１８０〜２４０℃の温度で０．１〜５時間、好ましくは０．１〜３時間反応させる。ついで、反応系の減圧度を上げながら反応温度を高め、最終的には１３３Ｐａ以下の減圧下、２４０〜３２０℃の温度で重縮合反応を行う。
反応の形式は、バッチ式、連続式あるいはバッチ式と連続式の組み合わせのいずれの反応でもよく、使用する装置は、槽型、管型あるいは塔型のいずれの形式であってもよい。
【００３５】
上記の方法で製造した芳香族ポリカーボネート中には、原料モノマー、触媒、エステル交換反応で副生する芳香族ヒドロキシ化合物、芳香族ポリカーボネートオリゴマー等の低分子量化合物が残存している。なかでも、原料モノマーと芳香族ヒドロキシ化合物は残留量が多く、耐熱老化性、耐加水分解性などの物性に悪影響を与える。
本発明においては、それらを除去することが好ましく、具体的にはベント式の押出機により連続的に脱揮することが挙げられる。その際、樹脂中に残留している塩基性エステル交換触媒をあらかじめ酸性化合物により中和し、失活させておくことにより脱揮中の副反応を抑え効率よく原料モノマーおよび芳香族ヒドロキシ化合物を除去することができる。
【００３６】
本発明において、添加する酸性化合物又はその前駆体には特に制限はなく、重縮合反応に使用する塩基性エステル交換触媒を中和する効果のあるものであればいずれも使用できる。具体的には、塩酸、硝酸、ホウ酸、硫酸、亜硫酸、リン酸、亜リン酸、次亜リン酸、ポリリン酸、アジピン酸、アスコルビン酸、アスパラギン酸、アゼライン酸、アデノシンリン酸、安息香酸、ギ酸、吉草酸、クエン酸、グリコール酸、グルタミン酸、グルタル酸、ケイ皮酸、コハク酸、酢酸、酒石酸、シュウ酸、ｐ−トルエンスルフィン酸、ｐ−トルエンスルホン酸、ナフタレンスルホン酸、ニコチン酸、ピクリン酸、ピコリン酸、フタル酸、テレフタル酸、プロピオン酸、ベンゼンスルフィン酸、ベンゼンスルホン酸、マロン酸、マレイン酸、等のブレンステッド酸及びそのエステル類が挙げられる。これらは、単独で使用しても、また、２種以上を組み合わせて使用してもよい。これらの酸性化合物又はその前駆体のうちスルホン酸化合物或いはそのエステル化合物、例えば、ｐ−トルエンスルホン酸、ｐ−トルエンスルホン酸メチル、ｐ−トルエンスルホン酸ブチル等が特に好ましい。
【００３７】
これらの酸性化合物又はその前駆体の添加量は、重縮合反応に使用した塩基性エステル交換触媒の中和量に対して０．１〜５０倍モル、好ましくは０．５〜３０倍モルの範囲で添加する。酸性化合物又はその前駆体を添加する時期としては、重縮合反応後であれば、いつでもよく、添加方法にも特別な制限はなく、酸性化合物又はその前駆体の性状や所望の条件に応じて、直接添加する方法、適当な溶媒に溶解して添加する方法、或いはペレットやフレーク状のマスターバッチを使用する方法等のいずれの方法でも良い。
【００３８】
本発明で用いられる二軸押出機としては、噛み合い型二軸押出機で、回転方向は同方向回転でも異方向回転でも良い。特に、酸性化合物添加部の後にベント部を有するものが好ましい。ベント数に制限は無いが、通常は２段から１０段の多段ベントが用いられる。また該押出機においては必要に応じて、安定剤、紫外線吸収剤、離型剤、着色剤等の添加剤を添加し、樹脂と混練することもできる。
【００３９】
本発明によれば、後記実施例に示される通り、分岐度ＭＩＲが１５以上、好ましくは１５〜３０、色相ＹＩが３．５以下、好ましくは１．５〜３．５、滞留熱安定性ＹＩが１０以下、好ましくは４〜１０、高荷重下ＭＩが１５以上、好ましくは１５〜５０である分岐化芳香族ポリカーボネートを容易に製造することができる。そして、本発明で製造される分岐化芳香族ポリカーボネートは、押出による加工および射出成形、特に高融体強度および押出物の優れた形状保持特性を有する材料を必要とするブロー成形による中空部品及び大型パネルの用途に好適である。
【００４０】
【実施例】
以下、実施例によって本発明を説明するが本発明はその要旨を超えない限り実施例に限定されるものではない。なお、実施例中の％および部は特に断らない限り重量％または重量部である。また、実施例、比較例において得られたポリカーボネートの物性は以下のようにして測定した。
【００４１】
（１）粘度平均分子量（Ｍｖ）：
６ｇ／ｌの塩化メチレン溶液をウベローデ粘度計を用い固有粘度を測定し、次式により粘度平均分子量を求めた。
【００４２】
【数１】
［η］＝１．２３×１０^-4（Ｍｖ）^0.83
【００４３】
（２）色相（ＹＩ）：
３ｍｍ厚のプレスシートについて、カラーテスター（スガ試験機株式会社製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値を計算した。
ＹＩ＝（１００／Ｙ）×（１．２８×Ｘ−１．０６×Ｚ）
このＹＩ値が大きいほど着色していることを示す。
【００４４】
（３）分岐度（ＭＩＲ）：
２６０℃における２１．６ｋｇと２．１６ｋｇの荷重に対して１０分間に押し出されたサンプル重量（ｇ）を測定し、両者の比で表す。この値が大きいほど分岐化の度合いが大きいことを示す。
【００４５】
（４）滞留熱安定性試験（耐熱色相ＹＩ）
３６０℃、１０分間滞留で５ショット目の条件で製作し、カラーテスター（スガ試験機株式会社製ＳＣ−１−ＣＨ）により透過法で測定した。
【００４６】
［実施例１］
窒素ガス雰囲気下、ジフェニルカーボネート、ビスフェノールＡ及び分岐剤として、表１に示す化合物Ａ（式６参照）をそれぞれ２０５．０モル／時、１９７．１モル／時および０．５９モル（ビスフェノールＡ１モルに対し、０．３モル％）の送量となるように、窒素雰囲気下１４０℃に調製された原料混合槽に連続的に送液した。
調製した原料混合液を原料導入管を介して、２２０℃、１．３３×１０⁴Ｐａに制御した容量１００Ｌの第一竪型撹拌重合槽内に連続供給し、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った。また、上記混合物の供給を開始すると同時に、触媒として２重量％の炭酸セシウム水溶液を３．２ｍｌ／時（ ビスフェノールＡ１モルに対し、１×１０^-6 モル）の流量で連続供給した。
【００４７】
槽底より排出された重合液は、引き続き、第２、第３の容量１００Ｌの竪型攪拌重合槽、ならびに第４の容量１５０Ｌの横型重合槽に逐次連続供給され、第４重合槽底部のポリマー排出口から抜き出された。次に、溶融状態のままで、このポリマーを２軸押出機に送入し、ｐ−トルエンスルホン酸ブチル（触媒として使用した炭酸セシウムに対して１０倍モル量）を連続して混練し、ダイを通してストランド状として、カッターで切断してペレットを得た。
第２〜第４重合槽での反応条件は、それぞれ第２重合槽（２４０℃、２．００×１０³Ｐａ、７５ｒｐｍ）、第３重合槽（２７０℃、６６．７Ｐａ、７５ｒｐｍ）、第４重合槽（２８０℃、６６．７Ｐａ、１０ｒｐｍ）で、反応の進行とともに高温、高真空、低攪拌速度に条件設定した。
また、反応の間は、第２〜第４重合槽の平均滞留時間が６０分となるように液面レベルの制御を行い、また、同時に副生するフェノールの留去も行った。
粘度平均分子量２４１００のポリカーボネートが得られ、これを３ｍｍ厚みの試験片に射出成形し色相（ＹＩ）を測定した。さらに２６０℃における分岐度（ＭＩＲ）の測定および滞留熱安定性試験（耐熱色相ＹＩ）を実施した。結果を表１に示す。
【００４８】
［実施例２〜３］
表１に示す分岐剤（化合物Ｂ、化合物Ｃ）を用いること以外は実施例１と同様にしてポリマーを製造した。結果を表１に示す。
【００４９】
［比較例１］
実施例１において、分岐剤として１，１，１−トリス（４−ヒドロキシルフェニル）エタン（ＴＨＰＥ）を用いた以外は、実施例１と同様にしてポリマーを製造した。結果を表１に示す。
【００５０】
［比較例２］
実施例１において、分岐剤として１，３，５−トリス（４−ヒドロキシフェニル）ベンゼン（ＴＨＰＢ）を用いた以外は、実施例１と同様にしてポリマーを製造した。結果を表１に示す。
【００５１】
［比較例３］
分岐剤を用いない以外は、実施例１と同様にしてポリマーを製造した。結果を表１に示す。
【００５２】
表１から、本発明方法で得られた芳香族ポリカーボネートは、分岐剤の使用により流動性、成形性が向上していることが分かる。また、従来の分岐剤を用いた方法で得られた芳香族ポリカーボネートと比較して、分岐度（ＭＩＲ）は同等程度であるが、色相ＹＩ、滞留熱安定性（耐熱色相ＹＩ）及び高荷重下ＭＩが顕著に優れていることが分かる。
【００５３】
【表１】

【００５４】
＊１：化合物Ａ＝式（６）の化合物
【化１２】

＊２：化合物Ｂ＝式（１０）の化合物
【化１３】

＊３：化合物Ｃ＝式（１２）の化合物
【化１４】

【発明の効果】
本発明によれば、高荷重下での流動性が改良され、さらに色相や滞留熱安定性も向上した分岐化芳香族ポリカーボネートが製造される。従って、押出による加工および射出成形、特に高融体強度および押出物の優れた形状保持特性を有する材料を必要とするブロー成形による中空部品及び大型パネルの用途に好適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a branched aromatic polycarbonate having excellent quality and a method for producing the same. More specifically, the present invention relates to a branched aromatic polycarbonate having improved fluidity under high load and further improved hue and retention stability, and a method for producing the same.
[0002]
[Prior art]
Aromatic polycarbonate is excellent in mechanical properties such as impact resistance, heat resistance and transparency, and is used in various fields in various fields.
By the way, generally used aromatic polycarbonate has a linear molecular structure, and a polycarbonate having such a molecular structure may be inferior in melt elasticity, melt strength, etc. during melt molding. Improvement of molding characteristics such as melt elasticity and melt strength is desired. As a method for improving the molding properties such as melt elasticity and melt strength of such polycarbonate, conventionally, 1,1,1-tris (4-hydroxyphenyl) ethane (as a branching agent together with bisphenol A by an interfacial polymerization method) A method of branching polycarbonate using a polyfunctional compound such as THPE), 1,3,5-tris (4-hydroxyphenyl) benzene is known (Japanese Patent Publication No. 44-17149, Japanese Patent Publication No. 47). -2918, JP-A-2-55725, JP-A-4-89824, etc.).
[0003]
However, the aromatic polycarbonate has a high melt viscosity even if it has a linear structure, and the polycarbonate into which a branched structure is introduced by copolymerization of a polyfunctional compound further increases the melt viscosity and decreases the fluidity. End up. As described above, the polycarbonate having a high melt viscosity and inferior fluidity has difficulty in obtaining a uniform molded product stably due to limited molding conditions and molding unevenness.
[0004]
In order to solve these problems, various attempts have been made in the melt polymerization method using a carbonic acid diester and an aromatic dihydroxy compound. The agent decomposes at a high temperature and the effect of branching does not appear, and further, coloring or satisfactory results cannot be obtained (JP-A-4-89824, JP-A-6-136112, No. 7-37517, JP-B-7-116285, etc.).
[0005]
[Problems to be solved by the invention]
Accordingly, the present invention is intended to solve the problems associated with the prior art as described above, a branched aromatic polycarbonate having improved fluidity under high load, and further improved hue and retention stability. It aims at providing the manufacturing method.
[0006]
[Means for Solving the Problems]
The present inventors have intensively studied to find a branched aromatic polycarbonate excellent in hue and melt characteristics such as melt strength, and produce a branched aromatic polycarbonate using a specific amount of a specific branching agent. As a result, it was found that the fluidity under high load was improved and that the hue and residence heat stability were also improved, and the present invention was completed.
[0007]
That is, the present invention provides a compound represented by the following formula (1) as a branching agent when producing an aromatic polycarbonate by reacting a carbonic acid diester with an aromatic dihydroxy compound as a raw material in the presence of a transesterification catalyst. Is polymerized using 0.05 to 0.8 mol% of the aromatic dihydroxy compound as a raw material, in a method for producing a branched aromatic polycarbonate.
The present invention also provides a compound represented by the following formula (2) as a branching agent when producing an aromatic polycarbonate by reacting a carbonic acid diester with an aromatic dihydroxy compound as a raw material in the presence of a transesterification catalyst. Is polymerized using 0.05 to 0.8 mol% of the aromatic dihydroxy compound as a raw material, in a method for producing a branched aromatic polycarbonate.
In addition, in the present invention , 0.05 to 0.8 mol% of the following formula (1) and / or the carbonic acid diester, the aromatic dihydroxy compound, and the raw material aromatic dihydroxy compound in the presence of the transesterification catalyst. Obtained by reacting the branching agent represented by (2), the degree of branching MIR is 15 or more, the hue YI is 3.5 or less, the residence heat stability YI is 10 or less, and the MI under high load is 15 or more. The present invention relates to a branched aromatic polycarbonate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described.
The branched aromatic polycarbonate of the present invention uses a carbonic acid diester and an aromatic dihydroxy compound as raw materials, and further, as a branching agent, one or more carboxyl groups, carboxylic acid ester groups or halocarbonyl groups in one molecule, and A compound having two or more hydroxyl groups can be obtained by melt polycondensation in the presence of a transesterification catalyst.
[0009]
The carbonic acid diester used in the present invention is usually represented by the following general formula (3).
Formula (3)

(In the formula, G and G ′ are an aliphatic group or substituted aliphatic group having 1 to 18 carbon atoms, or an aromatic group or substituted aromatic group, and G and G ′ may be the same or different. .)
[0010]
Examples of the carbonic acid diester represented by the general formula (3) include dialkyl carbonate compounds such as dimethyl carbonate, diethyl carbonate and di-t-butyl carbonate, and substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate. . Diphenyl carbonate and substituted diphenyl carbonate are preferable, and diphenyl carbonate is particularly preferable. These carbonic acid diesters may be used alone or in admixture of two or more.
[0011]
The aromatic dihydroxy compound used in the present invention is represented by the following formula (4). Formula (4)
[Formula 4]

[0012]
Wherein W is a single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or -O -, - S -, - CO -, - SO -, - SO 2 - those selected from the group consisting of divalent groups represented by, Y and Z are carbonized 1-6 halogen atoms or carbon atoms It is a hydrogen group, p and q are integers of 0 to 2, and Y and Z, and p and q may be the same or different.
[0013]
Examples of the aromatic dihydroxy compound represented by the above formula (4) include bis (4-hydroxydiphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4-hydroxy-). 3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis Bisphenols such as (4-hydroxy-3,5-dibromophenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) cyclohexane; 4,4′-dihydroxybiphenyl , 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl and the like; bis (4-hydroxypheny And bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone and the like. Particularly preferred is 2,2-bis (4-hydroxyphenyl) propane (hereinafter abbreviated as bisphenol A).
These aromatic dihydroxy compounds are used alone or as a mixture of two or more.
[0014]
In producing the aromatic polycarbonate in the present invention, the carbonic acid diester is used in excess relative to the aromatic dihydroxy compound. That is, it is used in a molar ratio of 1.01-1.30, preferably 1.02-1.20, relative to the aromatic dihydroxy compound. Under the same reaction conditions, the smaller the molar ratio, the higher the reaction rate and the higher the viscosity average molecular weight of the polycarbonate. Further, when the molar ratio is increased within this range, the reaction rate is decreased and the viscosity average molecular weight is decreased. When the molar ratio is less than 1.01, the amount of terminal OH groups of the resulting polycarbonate is increased, and the reactivity is increased, but the thermal stability, hydrolysis resistance, etc. are reduced, making it unsuitable for normal use. . When it exceeds 1.30, it becomes difficult to produce an aromatic polycarbonate having a desired molecular weight.
[0015]
In the present invention, a specific amount of a compound having one or more carboxyl groups, carboxylic acid ester groups or halocarbonyl groups, and two or more hydroxyl groups in one molecule is used. As such a compound, for example, compounds represented by the general formulas (1) and (2) can be used.
[0016]
Formula (1)
[Chemical formula 5]

[0017]
(In the formula, A ring and B ring, a carboxyl group, a carboxylic acid ester group or a halo group, the ester group is an aliphatic substituted or aromatic group with a halogen atom .X is A single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or -O-, -S-, -CO -, - SO -, - selected from the group consisting of divalent groups represented by) - SO _2.
[0018]
Formula (2)
[Chemical 6]

[0019]
(In the formula, at least one of C ring, D ring, E ring and F ring has a carboxyl group, a carboxylic acid ester group or a halocarbonyl group. At this time, the ester group is substituted with a halogen atom. X is a single bond, alkylene group having 1 to 8 carbon atoms, alkylidene group having 2 to 8 carbon atoms, cycloalkylene group having 5 to 15 carbon atoms, or 5 to 15 carbon atoms. (It is selected from the group consisting of a cycloalkylidene group or a divalent group represented by —O—, —S—, —CO—, —SO—, —SO ₂ —).
[0020]
Specific examples of such a compound include compounds represented by the following formula.
[Chemical 7]

[0021]
[Chemical 8]

[0022]
[Chemical 9]

[0023]
[Chemical Formula 10]

[0024]
Embedded image

[0025]
Of these, the formulas (5) to (14) are particularly preferably used. Such polyfunctional compounds for the aromatic dihydroxy compound of the raw material, 0.05 to 0.8 mol%, particularly preferably used by adding an amount of 0.1 to 0.6 mol%. These may be used alone or in admixture of two or more.
If the said compound is used, compared with the branched polymer which shows an equivalent branching degree, the fluidity | liquidity under a high load is very good, and also it is excellent in hue and residence heat stability. This is presumably because the compound acts as a branching agent, and a carboxyl group, a carboxylic acid ester group and / or a halocarbonyl group in the compound generates an ester bond by polymerization.
[0026]
When producing an aromatic polycarbonate by a transesterification method, a transesterification catalyst is usually used. As the transesterification catalyst used in the present invention, an alkali metal compound and / or an alkaline earth metal compound is mainly used, and a basic boron compound, a basic phosphorus compound, a basic ammonium compound or an amine compound is supplementarily used. It is also possible to use a basic compound such as These catalysts may be used alone or in combination of two or more.
[0027]
The catalyst is used in an amount of 1 × 10 ⁻⁹ to 1 × 10 ⁻³ mol per mol of the aromatic dihydroxy compound, and particularly good alkali metal compounds and / or in terms of physical properties and handling. the alkaline earth compound 1 × 10 over ⁸ to 1 × 10 ^-5 moles per 1 mole of the aromatic dihydroxy compound, preferably in a range of 2 × 10 over ⁸ to 8 × 10 ^-6 mol. If the amount is less than this amount, the polymerization activity necessary for producing a polycarbonate having a predetermined molecular weight and a terminal hydroxyl group cannot be obtained. If the amount is more than this amount, the polymer hue deteriorates and the number of branches increases.
[0028]
Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, carbonate Cesium, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, Sodium phenyl borohydride, potassium potassium phenide, lithium phenyl phenide, cesium phenyl phenide, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, 2 hydrogen phosphates Lithium, 2 potassium hydrogen phosphate, 2 lithium hydrogen phosphate, 2 cesium hydrogen phosphate, 2 sodium phenyl phosphate, 2 potassium phenyl phosphate, 2 lithium phenyl phosphate, 2 cesium phenyl phosphate, sodium, potassium, lithium, Examples include cesium alcoholate, phenolate, and disodium salt, dipotassium salt, dilithium salt, and dicesium salt of bisphenol A.
[0029]
Examples of the alkaline earth metal compound include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate, Examples thereof include magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, and strontium stearate.
[0030]
Specific examples of basic boron compounds include tetramethyl boron, tetraethyl boron, tetrapropyl boron, tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron, trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron, triethylphenyl boron, tributyl. Examples thereof include hydroxides such as benzyl boron, tributyl phenyl boron, tetraphenyl boron, benzyl triphenyl boron, methyl triphenyl boron, and butyl triphenyl boron.
[0031]
Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, and quaternary phosphonium salt.
[0032]
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, such as butyl triphenyl ammonium hydroxide and the like.
[0033]
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.
[0034]
The transesterification reaction is generally carried out in a multistage process having two or more stages. Specifically, the reaction in the first stage is performed at a temperature of 120 to 260 ° C., preferably 180 to 240 ° C. under a reduced pressure of 9.3 × 10 ^{4 to} 1.33 × 10 ³ Pa. The reaction is carried out for a time, preferably 0.1 to 3 hours. Next, the reaction temperature is raised while raising the degree of vacuum of the reaction system, and finally a polycondensation reaction is performed at a temperature of 240 to 320 ° C. under a reduced pressure of 133 Pa or less.
The type of reaction may be any of batch type, continuous type or a combination of batch type and continuous type, and the apparatus used may be any type of tank type, tube type or column type.
[0035]
Low molecular weight compounds such as raw material monomers, catalysts, aromatic hydroxy compounds by-produced by transesterification, and aromatic polycarbonate oligomers remain in the aromatic polycarbonate produced by the above method. Among these, the raw material monomer and the aromatic hydroxy compound have a large residual amount, which adversely affects physical properties such as heat aging resistance and hydrolysis resistance.
In the present invention, it is preferable to remove them, and specific examples include continuous devolatilization with a vent type extruder. At that time, the basic transesterification catalyst remaining in the resin is neutralized with an acidic compound in advance and deactivated to suppress side reactions during devolatilization and efficiently remove raw material monomers and aromatic hydroxy compounds. can do.
[0036]
In the present invention, the acidic compound to be added or its precursor is not particularly limited, and any compound can be used as long as it has an effect of neutralizing the basic transesterification catalyst used in the polycondensation reaction. Specifically, hydrochloric acid, nitric acid, boric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, adipic acid, ascorbic acid, aspartic acid, azelaic acid, adenosine phosphoric acid, benzoic acid, Formic acid, valeric acid, citric acid, glycolic acid, glutamic acid, glutaric acid, cinnamic acid, succinic acid, acetic acid, tartaric acid, oxalic acid, p-toluenesulfinic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, nicotinic acid, picrine Examples thereof include Bronsted acids such as acid, picolinic acid, phthalic acid, terephthalic acid, propionic acid, benzenesulfinic acid, benzenesulfonic acid, malonic acid, maleic acid, and esters thereof. These may be used alone or in combination of two or more. Of these acidic compounds or precursors thereof, sulfonic acid compounds or ester compounds thereof, for example, p-toluenesulfonic acid, methyl p-toluenesulfonate, butyl p-toluenesulfonate, and the like are particularly preferable.
[0037]
The addition amount of these acidic compounds or precursors thereof is in the range of 0.1 to 50 times mol, preferably 0.5 to 30 times mol, of the neutralization amount of the basic transesterification catalyst used in the polycondensation reaction. Add in. The timing of adding the acidic compound or its precursor may be any time after the polycondensation reaction, and there is no particular limitation on the addition method, depending on the properties of the acidic compound or its precursor and the desired conditions, Any method such as a method of adding directly, a method of adding by dissolving in an appropriate solvent, or a method of using a pellet or flaky master batch may be used.
[0038]
The twin-screw extruder used in the present invention is a meshing twin-screw extruder, and the rotational direction may be the same or different direction. In particular, those having a vent part after the acidic compound addition part are preferred. The number of vents is not limited, but usually a multistage vent of 2 to 10 stages is used. In the extruder, if necessary, additives such as a stabilizer, an ultraviolet absorber, a release agent, and a colorant can be added and kneaded with the resin.
[0039]
According to the present invention, the branching degree MIR is 15 or more, preferably 15 to 30, the hue YI is 3.5 or less, preferably 1.5 to 3.5, and the residence heat stability YI, as shown in the Examples below. Is 10 or less, preferably 4 to 10, and MI under high load is 15 or more, preferably 15 to 50, can be easily produced. The branched aromatic polycarbonates produced by the present invention are processed by extrusion and injection molding, in particular, hollow parts by blow molding that require materials having high melt strength and excellent shape retention properties of extrudates, and large-sized parts. Suitable for panel applications.
[0040]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to an Example, unless the summary is exceeded. In addition, unless otherwise indicated,% and part in an Example are weight% or a weight part. The physical properties of the polycarbonates obtained in the examples and comparative examples were measured as follows.
[0041]
(1) Viscosity average molecular weight (Mv):
The intrinsic viscosity of a 6 g / l methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was determined by the following formula.
[0042]
[Expression 1]
[Η] = 1.23 × 10 ⁻⁴ (Mv) ^0.83
[0043]
(2) Hue (YI):
For a 3 mm-thick press sheet, a color tester (SC-1-CH manufactured by Suga Test Instruments Co., Ltd.) was used to measure the tristimulus values XYZ, which are the absolute values of the colors. The value was calculated.
YI = (100 / Y) × (1.28 × X−1.06 × Z)
It shows that it colors, so that this YI value is large.
[0044]
(3) Degree of branching (MIR):
The sample weight (g) extruded for 10 minutes with respect to the load of 21.6 kg and 2.16 kg at 260 degreeC is measured, and it represents with ratio of both. A larger value indicates a greater degree of branching.
[0045]
(4) Stability thermal stability test (heat resistant hue YI)
The sample was produced at 360 ° C. for 10 minutes under the condition of the fifth shot, and measured by a transmission method using a color tester (SC-1-CH manufactured by Suga Test Instruments Co., Ltd.).
[0046]
[Example 1]
In a nitrogen gas atmosphere, diphenyl carbonate, bisphenol A and a branching agent were mixed with compound A (see formula 6) shown in Table 1 at 205.0 mol / hr, 197.1 mol / hr and 0.59 mol (bisphenol A 1 mol), respectively. In contrast, the solution was continuously fed to a raw material mixing tank prepared at 140 ° C. in a nitrogen atmosphere so that the feed amount was 0.3 mol%.
The prepared raw material mixture is continuously supplied into the first vertical stirring polymerization tank with a capacity of 100 L controlled at 220 ° C. and 1.33 × 10 ⁴ Pa through the raw material introduction pipe, and the average residence time becomes 60 minutes. Thus, the liquid level was kept constant while controlling the valve opening degree provided in the polymer discharge line at the bottom of the tank. At the same time as the supply of the above mixture was started, a 2 wt% aqueous cesium carbonate solution was continuously supplied as a catalyst at a flow rate of 3.2 ml / hour (1 × 10 ⁻⁶ mol relative to 1 mol of bisphenol A).
[0047]
The polymerization liquid discharged from the bottom of the tank is continuously continuously supplied to the second and third capacity 100 L vertical stirring polymerization tanks and the fourth capacity 150 L horizontal polymerization tank, and the polymer at the bottom of the fourth polymerization tank It was extracted from the outlet. Next, in a molten state, this polymer was fed into a twin-screw extruder, and butyl p-toluenesulfonate (10-fold molar amount relative to cesium carbonate used as a catalyst) was continuously kneaded, As a strand shape, a pellet was obtained by cutting with a cutter.
The reaction conditions in the second to fourth polymerization tanks were the second polymerization tank (240 ° C., 2.00 × 10 ³ Pa, 75 rpm), the third polymerization tank (270 ° C., 66.7 Pa, 75 rpm), and the fourth, respectively. In the polymerization tank (280 ° C., 66.7 Pa, 10 rpm), conditions were set to high temperature, high vacuum, and low stirring speed as the reaction progressed.
During the reaction, the liquid level was controlled so that the average residence time in the second to fourth polymerization tanks was 60 minutes, and at the same time, the by-produced phenol was distilled off.
A polycarbonate having a viscosity average molecular weight of 24100 was obtained, and this was injection-molded into a test piece having a thickness of 3 mm, and the hue (YI) was measured. Further, the degree of branching (MIR) at 260 ° C. and the residence heat stability test (heat resistant hue YI) were carried out. The results are shown in Table 1.
[0048]
[Examples 2-3]
A polymer was produced in the same manner as in Example 1 except that the branching agents (Compound B and Compound C) shown in Table 1 were used. The results are shown in Table 1.
[0049]
[Comparative Example 1]
In Example 1, a polymer was produced in the same manner as in Example 1 except that 1,1,1-tris (4-hydroxylphenyl) ethane (THPE) was used as a branching agent. The results are shown in Table 1.
[0050]
[Comparative Example 2]
In Example 1, a polymer was produced in the same manner as in Example 1 except that 1,3,5-tris (4-hydroxyphenyl) benzene (THPB) was used as a branching agent. The results are shown in Table 1.
[0051]
[Comparative Example 3]
A polymer was produced in the same manner as in Example 1 except that the branching agent was not used. The results are shown in Table 1.
[0052]
From Table 1, it can be seen that the aromatic polycarbonate obtained by the method of the present invention has improved fluidity and moldability by using a branching agent. Compared with the aromatic polycarbonate obtained by the conventional method using a branching agent, the degree of branching (MIR) is comparable, but the hue YI, residence heat stability (heat resistant hue YI) and under high load. It can be seen that MI is remarkably superior.
[0053]
[Table 1]

[0054]
* 1: Compound A = Compound of formula (6)

* 2: Compound B = Compound of formula (10)

* 3: Compound C = compound of formula (12)

【The invention's effect】
According to the present invention, a branched aromatic polycarbonate having improved fluidity under a high load and further improved hue and residence heat stability is produced. Accordingly, it is suitable for processing by extrusion and injection molding, particularly for blow-molded hollow parts and large panels that require materials having high melt strength and excellent shape retention properties of extrudates.

Claims (4)

When producing an aromatic polycarbonate by reacting a carbonic acid diester and an aromatic dihydroxy compound as a raw material in the presence of a transesterification catalyst, the compound represented by the following formula (1) is used as a raw material for the aromatic compound of the raw material. The manufacturing method of the branched aromatic polycarbonate characterized by superposing | polymerizing using 0.05-0.8 mol% with respect to a dihydroxy compound.

(In the formula, A ring and B ring, a carboxyl group, a carboxylic acid ester group or a halo group, the ester group is an aliphatic substituted or aromatic group with a halogen atom .X is A single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or -O-, -S-, -CO -, - SO -, - selected from the group consisting of divalent groups represented by) - SO _2. When producing an aromatic polycarbonate by reacting a carbonic acid diester with an aromatic dihydroxy compound as a raw material in the presence of a transesterification catalyst, a compound represented by the following formula (2) is used as a raw material for the aromatic compound of the raw material. The manufacturing method of the branched aromatic polycarbonate characterized by superposing | polymerizing using 0.05-0.8 mol% with respect to a dihydroxy compound.

(In the formula, at least one of C ring, D ring, E ring and F ring has a carboxyl group, a carboxylic ester group or a halocarbonyl group, and the ester group may be substituted with a halogen atom. X is a single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, or a cycloalkylidene group having 5 to 15 carbon atoms. Or, it is selected from the group consisting of divalent groups represented by —O—, —S—, —CO—, —SO—, —SO ₂ —, and the two Xs may be the same or different. In the above reaction, a catalyst containing 1 × 10 ⁻⁸ to 1 × 10 ⁻⁵ mol of alkali metal and / or alkaline earth metal is used with respect to 1 mol of the aromatic dihydroxy compound as a raw material. The manufacturing method of the branched aromatic polycarbonate in any one of 1-2. In the presence of a transesterification catalyst, 0.05 to 0.8 mol% of the carbonic acid diester, the aromatic dihydroxy compound, and the raw material aromatic dihydroxy compound are represented by the following formulas (1) and / or (2). A branching agent having a branching degree MIR of 15 or more, a hue YI of 3.5 or less, a residence heat stability YI of 10 or less, and a high load MI of 15 or more. Aromatic polycarbonate.

(In the formula, A ring and B ring, a carboxyl group, a carboxylic acid ester group or a halo group, the ester group is an aliphatic substituted or aromatic group with a halogen atom .X is A single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or -O-, -S-, -CO -, - SO -, - selected from the group consisting of divalent groups represented by) - SO _2.

(In the formula, at least one of C ring, D ring, E ring and F ring has a carboxyl group, a carboxylic ester group or a halocarbonyl group, and the ester group may be substituted with a halogen atom. X is a single bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, or a cycloalkylidene group having 5 to 15 carbon atoms. Or, it is selected from the group consisting of divalent groups represented by —O—, —S—, —CO—, —SO—, —SO ₂ —, and the two Xs may be the same or different.