JP4492774B2 - Cover layer film for optical information recording media - Google Patents

Description

（式中、Ｒ₁ 〜Ｒ₄ は、各々独立して、水素原子、炭素数１〜５のアルキル基、炭素数６〜１２のアリール基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基、又は炭素数７〜１７のアラルキル基を表す。これらの基に炭素原子を有する場合には置換基として、炭素数１〜５のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基を有することもできる。）
【００１２】
【化６】

（式中、Ｒ₅ 〜Ｒ₈ は、各々独立して、水素、炭素数１〜５のアルキル基、炭素数６〜１２のアリール基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基、または炭素数７〜１７のアラルキル基であり、これらの基に炭素原子を有する場合には置換基として、炭素数１〜５のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基を有することもできる。Ｒ₉ 〜Ｒ₁₂は、水素、炭素数１〜５のアルキル基、炭素数６〜１２のアリール基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基又は炭素数７〜１７のアラルキル基であり、これらの基に炭素原子を有する場合には置換基として、炭素数１〜５のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基を有することもできる。Ｒ₁₃は炭素数１〜６の脂肪族基を表すか単に結合を表す。Ｘは、−SiO(Ｒ₁₄)(Ｒ₁₅）−および／または−SiO(Ｒ₁₆)(Ｒ₁₇）−の単独重合体、ブロック共重合体またはランダム共重合体を表し、重合度は０〜２００であり、Ｒ₁₄〜Ｒ₁₇は、各々独立して水素、炭素数１〜５のアルキル基、炭素数６〜１２のアリール基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基、又は炭素数７〜１７のアラルキル基であり、これらの基に炭素原子を有する場合には置換基として、炭素数１〜５のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基を有することもできる。）
【００１３】
【化７】

（式中、Ｒ₁₈〜Ｒ₁₉は、各々独立して、水素、炭素数１〜１０のアルキル基、炭素数６〜１２のアリール基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基、炭素数７〜１７のアラルキル基であり、これらの基に炭素原子を有する場合には置換基として、炭素数１〜５のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基を有することもできる。Ｙは、
【化８】

であり、ここにＲ₂₀，Ｒ₂₁はそれぞれ、水素、炭素数１〜１０のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基又は炭素数６〜１２のアリール基を表すか、Ｒ₂₀とＲ₂₁が一緒に結合して、炭素数３〜６の炭素環または複素環を形成する基を表し、これらの基に炭素原子を有する場合には置換基として、炭素数１〜５のアルキル基、炭素数２〜５のアルケニル基、炭素数１〜５のアルコキシ基を有することもできる。ａは０〜２０の整数を表す。）
【００１４】
本発明の光情報記録媒体用カバー層フィルムに用いられるポリカーボネート樹脂は、前記の一般式（Ａ）と一般式（Ｂ）、または一般式（Ａ）と一般式（Ｂ）と一般式（Ｃ）の化合物とを、炭酸エステル形成化合物と反応させることによって、製造することができるものであり、ビスフェノールＡから誘導されるポリカーボネートを製造する際に用いられている公知の方法、例えばビスフェノール類とホスゲンとの直接反応（ホスゲン法）、あるいはビスフェノール類とビスアリールカーボネートとのエステル交換反応（エステル交換法）などの方法を採用することができる。
【００１５】
本発明に用いられる一般式（Ａ）の化合物としては、具体的には９，９−ビス（４−ヒドロキシ−２−メチルフェニル）フルオレン、９，９−ビス（４−ヒドロキシ−３−メチルフェニル）フルオレン、９，９−ビス（４−ヒドロキシフェニル）フルオレン、３，６−ジメチル−９，９−ビス（４−ヒドロキシフェニル）フルオレン、９，９−ビス（３−メトキシ−４−ヒドロキシフェニル）フルオレン、９，９−ビス（３−エトキシ−４−ヒドロキシフェニル）フルオレン、９，９−ビス（３−エチル−４−ヒドロキシフェニル）フルオレン、４，５−ジメチル−９，９−ビス（４−ヒドロキシフェニル）フルオレン、９，９−ビス（３−フェニル−４−ヒドロキシフェニル）フルオレン、３，６−ジメチル−９，９−ビス（３−メチル−４−ヒドロキシフェニル）フルオレン及び３，６−ジフェニル−９，９−ビス（４−ヒドロキシフェニル）フルオレン等を挙げることができる。中でも特に、９，９−ビス（４−ヒドロキシフェニル）フルオレン、９，９−ビス（４−ヒドロキシ−３−メチルフェニル）フルオレン、９，９−ビス（４−ヒドロキシ−２−メチルフェニル）フルオレンが好ましい。これらの化合物は２種類以上併用して使用することも可能である。
【００１６】
本発明に用いられる一般式（Ｂ）の化合物としては、具体的には、下記のものが例示される。
【００１７】
【化９】

【００１８】
これらは、２種類以上併用することも可能である。Ｘには、ジメチルシロキサンが１〜１００個またはジフェニルシロキサンが１〜１００個含まれるものおよびそれらのランダム共重合体が好ましい。中でも、特に、α，ω−ビス[3-(o-ヒドロキシフェニル）プロピル］ポリジメチルジフェニルランダム共重合シロキサン、α，ω−ビス[3-(o-ヒドロキシフェニル）プロピル］ポリジメチルシロキサンが好ましい。
【００１９】
本発明中の一般式（Ｃ）の化合物としては、具体的には4,4'−ビフェニルジオール、ビス（4-ヒドロキシフェニル）メタン、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）スルホン、ビス（4-ヒドロキシ−3-メチルフェニル）スルホン、ビス（4-ヒドロキシフェニル）スルホキシド、ビス（4-ヒドロキシフェニル）スルファイド、ビス（4-ヒドロキシフェニル）ケトン、1,1-ビス（4-ヒドロキシフェニル）エタン、2,2-ビス（4-ヒドロキシフェニル）プロパン（ビスフェノ−ルＡ；BPA ）、2,2-ビス（4-ヒドロキシフェニル）ブタン、1,1-ビス（4-ヒドロキシフェニル）シクロヘキサン（ビスフェノ−ルＺ；BPZ ）、2,2-ビス（4-ヒドロキシ−3-メチルフェニル）プロパン（ジメチルビスフェノールＡ）、2,2-ビス（4-ヒドロキシ−3,5-ジメチルフェニル）プロパン、1,1-ビス（4-ヒドロキシフェニル）−1-フェニルエタン（ビスフェノールＡＰ；BPAP）、ビス（4-ヒドロキシフェニル）ジフェニルメタン、2,2-ビス（4-ヒドロキシ−3-アリルフェニル）プロパン、3,3,5-トリメチル−1,1-ビス（4-ヒドロキシフェニル）シクロヘキサン（トリメチルビスフェノール−Ｚ；TMBPZ ）などが例示される。これらは、２種類以上併用することも可能である。また、これらの中でも特に2,2-ビス（4-ヒドロキシフェニル）プロパンが好ましい。
【００２０】
また、本発明中の炭酸エステル形成化合物としては、例えばホスゲンや、ジフェニルカーボネート、ジ−ｐ−トリルカーボネート、フェニル−ｐ−トリルカーボネート、ジ−ｐ−クロロフェニルカーボネート、ジナフチルカーボネートなどのビスアリルカーボネートが挙げられる。これらの化合物は２種類以上併用して使用することも可能である。
【００２１】
ホスゲン法とエステル交換法では、一般式（Ａ）の化合物および一般式（Ｂ）の化合物の反応性を考慮した場合、ホスゲン法の方が好ましい。
【００２２】
前者のホスゲン法においては、通常酸結合剤および溶媒の存在下において、本発明における一般式（Ａ）の化合物と一般式（Ｂ）の化合物、または一般式（Ａ）の化合物と一般式（Ｂ）の化合物と一般式（Ｃ）の化合物とを、ホスゲンと反応させる。酸結合剤としては、例えばピリジンや、水酸化ナトリウム、水酸化カリウムなどのアルカリ金属の水酸化物などが用いられ、また溶媒としては、例えば塩化メチレン、クロロホルム、クロロベンゼン、キシレンなどが用いられる。さらに、縮重合反応を促進するために、トリエチルアミンのような第三級アミンなどの触媒を、また重合度調節には、フェノール、ｐ−ｔ−ブチルフェノール、p-クミルフェノール、アルキル置換フェノール類、ヒドロキシ安息香酸アルキル類やアルキルオキシフェノール類などの一官能基化合物を分子量調節剤として加える。さらに、所望に応じ亜硫酸ナトリウム、ハイドロサルファイトなどの酸化防止剤や、フロログルシン、イサチンビスフェノール、1,1,1-トリス（4-ヒドロキシフェニル）エタン、α，α',α"-トリス（4-ヒドロキシフェニル)-1,3,5-トリイソプロピルベンゼンなど分岐化剤を小量添加してもよい。反応は通常０〜１５０℃、好ましくは５〜４０℃の範囲とするのが適当である。反応時間は反応温度によって左右されるが、通常０．５分〜１０時間、好ましくは１分〜２時間である。また、反応中は、反応系のｐＨを１０以上に保持することが望ましい。
【００２３】
一方、後者のエステル交換法においては、本発明における一般式（Ａ）の化合物と一般式（Ｂ）の化合物または一般式（Ａ）の化合物と一般式（Ｂ）の化合物と一般式（Ｃ）の化合物とをビスアリールカーボネートと混合し、減圧下で高温において反応させる。この時、フェノール、ｐ−ｔ−ブチルフェノール、p-クミルフェノール、アルキル置換フェノール類、ヒドロキシ安息香酸アルキル類やアルキルオキシフェノール類などの一官能基化合物を分子量調節剤として加えてもよい。反応は通常１５０〜３５０℃、好ましくは２００〜３００℃の範囲の温度において行われ、また減圧度は最終で好ましくは１mmHg以下にして、エステル交換反応により生成した該ビスアリールカーボネートから由来するフェノール類を系外へ留去させる。反応時間は反応温度や減圧度などによって左右されるが、通常１〜１０時間程度である。反応は窒素やアルゴンなどの不活性ガス雰囲気下で行うことが好ましく、また、所望に応じ、酸化防止剤や分岐化剤を添加して反応を行ってもよい。
【００２４】
本発明においてホスゲン法を採用する場合は、用いられる三級アミン重合触媒として、例えばトリエチルアミン、トリ−ｎ−プロピルアミン、トリ−ｎ−ブチルアミン、Ｎ，Ｎ'-ジメチルシクロヘキシルアミン、Ｎ，Ｎ'-ジエチルアニリン、ジエチルアミノピリジン等があるが、触媒活性や洗浄除去の問題からトリエチルアミンが好ましい。重合触媒の添加量は、使用される全ビスフェノール類に対して、０．００１〜５mol%が好ましい。
【００２５】
本発明においてホスゲン法を採用する場合は、反応を効率よく行うため第四級アンモニウム塩を少量添加してもよい。具体的には、テトラメチルアンモニウムクロライド、トリメチルベンジルアンモニウムクロライド、トリエチルベンジルアンモニウムクロライド、テトラエチルアンモニウムブロマイド、テトラ−ｎ−ブチルアンモニウムアイオダイドなどが例示され、これらのうちトリメチルベンジルアンモニウムクロライド、トリエチルベンジルアンモニウムクロライドが好ましい。この第四級アンモニウム塩は、使用される全ビスフェノール類に対して、一般に０．００５〜５mol%使用されることが好ましい。
【００２６】
更に、本発明に分子量調節剤を用いる場合には特に一価フェノールが好ましく、具体的にはフェノールやブチルフェノール、オクチルフェノール、ノニルフェノール、デカニルフェノール、テトラデカニルフェノール、ヘプタデカニルフェノール、オクタデカニルフェノール等のアルキル置換フェノール；ヒドロキシ安息香酸ブチル、ヒドロキシ安息香酸オクチル、ヒドロキシ安息香酸ノニル、ヒドロキシ安息香酸デカニル、ヒドロキシ安息香酸ヘプタデカニル等のヒドロキシ安息香酸アルキルエステル；ブトキシフェノール、オクチルオキシフェノール、ノニルオキシフェノール、デカニルオキシフェノール、テトラデカニルオキシフェノール、ヘプタデカニルオキシフェノール、オクタデカニルオキシフェノール等のアルキルオキシフェノール類が例示される。この分子量調節剤の添加量は全ビスフェノール類に対して０．１〜５０ｍｏｌ％である。好ましくは、０．５〜１０mol%である。
【００２７】
これらの反応で合成された本発明のポリカーボネート樹脂は、光情報記録媒体用カバー層フィルムとして成形するための溶融押出フィルム成形、射出フィルム成形、圧縮フィルム成形、湿式フィルム成形など公知の成形法で成形可能であるが、溶融押出フィルム成形により、光記録媒体用カバー層フィルムとして成形されるには、容易に溶融押出フィルム成形できることが望ましく、極限粘度が０．２〜１．０ｄｌ／ｇの範囲であることが好ましい。
【００２８】
また、前記一般式（Ｂ）の使用量は光記録媒体用カバー層フィルムの強度を考慮すると、前記一般式（Ａ）及び一般式（Ｂ）及び一般式（Ｃ）の合計量に対して２０〜６０重量％が好ましい。前記一般式（Ｂ）が２０重量％未満では、剛直に成りすぎて脆く、６０重量％を越えると光記録媒体用カバー層フィルムとして必要な耐熱性が不足する。
【００２９】
前記の一般式（Ｃ）の使用は、諸性能の向上やコスト低減等のため使用可能であるが、特にビスフェノールＡを用いた場合、従来のビスフェノールＡ型ポリカーボネートとの相溶性がよく、リサイクル性や他品種押出機内の樹脂置換性が向上する利点を有する。光記録媒体用カバー層フィルムのリターデーション値を考慮すると、前記の一般式（Ｃ）は、前記の一般式（Ａ）及び一般式（Ｃ）の合計量に対して５０重量％未満が好ましい。前記の一般式（Ｃ）が前記の一般式（Ａ）及び一般式（Ｃ）の合計量に対して５０重量％以上ではリターデーション値が著しく悪化し不充分となる。
【００３０】
本発明のポリカーボネート樹脂は、従来の光記録媒体用カバー層フィルムの材料であるポリカーボネート樹脂と同様に高度に精製されたものが好ましい。具体的には、直径５０μｍ以上のダストが実質上検出されず、直径０．５〜５０μｍのダストが３×１０⁴ 以下、無機および有機残留塩素が２ｐｐｍ以下、残留アルカリ金属が２ｐｐｍ以下、残存水酸基２００ｐｐｍ以下、残存窒素量５ｐｐｍ以下、残存モノマー２０ｐｐｍ以下等の基準を可能な限り満たすように精製される。また、低分子量体除去や溶媒除去のため抽出等の後処理が行われる場合もある。また、原材料の一般式（Ａ）、一般式（Ｂ）および一般式（Ｃ）の化合物や炭酸エステル形成化合物等についても不純物や異性体などを極力低減した材料を用いることが好ましい。
【００３１】
本発明のポリカーボネート樹脂は光記録媒体用カバー層フィルム成形時に必要な安定性や離型性を確保するため、所望に応じて、ヒンダードフェノール系やホスファイト系酸化防止剤；シリコン系、脂肪酸エステル系、脂肪酸系、脂肪酸グリセリド系、密ろう等天然油脂などの滑剤や離型剤；ベンゾトリアゾール系、ベンゾフェノン系、ジベンゾイルメタン系、サリチレート系等の光安定剤；ポリアルキレングリコール、脂肪酸グリセリド等帯電防止剤などを適宜併用してよい。
【００３２】
さらにはコスト低減等の目的で、本発明のポリカーボネート樹脂と従来のビスフェノールＡ型ポリカーボネートと性能を損なわない範囲で任意に混合して使用する事も可能である。
【００３３】
本発明のポリカーボネート樹脂を用いた光記録媒体用カバー層フィルムは、通常溶融押出フィルム成形で成形する場合には、２３０〜３８０℃の範囲で成形されることが好ましく、溶融粘度が高化式フローテスター（２８０℃、15.7MPa 、ノズル径１mm×１０mm）の１×１０^-2ml/sec以上であることがあることが好ましい。１×１０^-2ml/sec未満では溶融粘度が大きすぎるため押出が難しく、成形温度や分子量により調整し、物性を損なわない範囲で成形可能な流動性を得ることが好ましい。
【００３４】
本発明の光記録媒体用カバー層フィルムは、接着層を介して記録面と接触するが、記録媒体外部に使用されるのみならず、多層化された記録面との間にも使用することができる。ここで用いられるフィルムは、光学的入出力信号を忠実に伝送することが必要であり、光学的等方性が求められるので、フィルム面に対して垂直方向、及びフィルム面の垂直方向から数１０°傾いた方向からシングルパスで通過する光に対し、リターデーション値２０ｎｍ以下、好ましくは１０ｎｍ以下が好ましい。さらにフィルム内でのリターデーション値のバラツキは５ｎｍ以下が好ましい。
【００３５】
本発明の光記録媒体用カバー層フィルムの厚みは、２０〜２００μｍであるが、好ましくは５０〜１５０μｍ、より好ましくは６０〜１００μｍである。
【００３６】
本発明の光記録媒体用カバー層フィルムの光透過率が３５０〜７００ｎｍの領域において７０％以上であることが、光学的入出力信号を忠実に伝送するために必要であるが、好ましくは８０％以上、より好ましくは８５％以上である。
【００３７】
また、本発明の光記録媒体用カバー層フィルムは、二次元の記録面からなる多層ディスクのみならず、ディスクの穴や溝の中の化学物質による三次元蛍光発光を読み取る方式の蛍光多層ディスクにも使用することができる。
【００３８】
【実施例】
次に実施例により、本発明をさらに詳細に説明するが、本発明はこれらの例によってなんら限定されるものではない。
【００３９】
実施例１
8.8%(w/v) の水酸化ナトリウム水溶液４９リットルに9,9-ビス（4-ヒドロキシ−3-メチルフェニル）フルオレン３．５kg（以下、BCFLと略称）とハイドロサルファイト１０ｇを加え溶解した。これにメチレンクロライド２５リットルを加え、１５℃に保ちながら撹拌しつつ、ホスゲン２．３kgを３０分かけて吹き込んだ。
吹き込み終了後、１分間激しく撹拌して反応液を乳化させ、p-ターシャルブチルフェノール８４g(以下、PTBPと略称）と下記ポリシロキサン化合物３．５kg（以下、Si1 と略称）とを加え、さらに１０分間撹拌後、２０mlのトリエチルアミンを加え、さらに６０分撹拌を継続し重合させた。
重合液を水相と有機相に分離し、有機相をリン酸で中和し、洗液の導電率が10μＳ/cm 以下になるまで水洗を繰り返した後、精製樹脂液を得た。得られた精製樹脂液0.5 μｍ径テフロンフィルターで濾過後、強攪拌されている６０℃の純水に樹脂液をゆっくり滴下し、溶媒を除去しつつ重合物を固形化した。固形物を濾過後、乾燥して白色粉末状重合体を得た。
この重合体は、メチレンクロライドを溶媒とする濃度0.5g／dlの溶液の温度20℃（ハギンズ定数0.45）における極限粘度［η］は0.38dl/gであった。
【００４０】
【化１０】

【００４１】
得られたポリカーボネート粉末にステアリン酸モノグリセリド300ppmを添加し、５０μｍポリマーフィルターを付けたベント付き５０ｍｍ押出機にて２８０℃で押出し、溶融ペレット化を行った。
【００４２】
得られたペレットを、水辺３本鏡面仕上げロールを備えた溶融フィルム押出機にて２８０℃で押出し、１５０ｍｍ幅の溶融成形フィルムを得た。得られたフィルムを２日間室温放置後、フィルムの厚み、幅方向の厚みムラ、６３３ｎｍにおけるリターデーション値、光透過率（波長３５０〜７００ｎｍ）を測定した。
また、得られたペレットの一部を樹脂温度３００℃で、金型温度１００℃、成形サイクル５０秒／枚の条件で、３ｍｍ厚の板状品を成形し、光線透過率、及びヘーズの測定を行った。
【００４３】
実施例２
Si1 の代わりに下記ポリシロキサン化合物２．３kg（以下、Si2 と略称）に変更し、PTBPを４８g に変更し、さらにBCFL投入と同時にトリエチルベンジルアンモニウムクロライド0.5g加えた以外は実施例１と同様に重合反応を行った。
得られた重合体の極限粘度［η］は0.28dl/gであった。実施例１と同様に成形後、物性測定を行った。
【００４４】
【化１１】

【００４５】
実施例３
Si1 の代わりに下記ポリシロキサン化合物３．５Kg（以下Si3 と略称）に変更し、PTBPの代わりにフェノール４８ｇ（以下PHと略称）に変更した以外は実施例１と同様に重合反応を行った。
得られた重合体の極限粘度［η］は0.29dl/gであった。実施例１と同様に成形後、物性測定を行った。
【００４６】
【化１２】

【００４７】
実施例４
BCFLを２．５kg、Si1 を１．８kgに変更し、さらにBCFL投入と同時に2,2-ビス（4-ヒドロキシフェニル）プロパン０．６０kg（以下BPA と略称）を加えた以外は、実施例１と同様に重合反応を行った。
得られた重合体の極限粘度［η］は0.35dl/gであった。実施例１と同様に成形後、物性測定を行った。
【００４８】
比較例１
実施例１のポリカーボネートの代わりに、市販のビスフェノールＡ型ポリカーボネート樹脂（三菱瓦斯化学（株）製ユーピロンS-2000）を用いた以外は実施例１と同様に成形後、物性測定を行った。
【００４９】
比較例２
BCFLの代わりに、9,9-ビス（4-ヒドロキシフェニル）フルオレン２．６kg（以下BFL と略称）とBPA ２．５kgを用い、PTBPの代わりにm-ヒドロキシベンジルアルコールとカプロラクトンの反応物（モル比１／２０）２．０kgに変更し、Si1 を用いなかった以外は、実施例１と同様に反応重合を行った。
得られた重合体の極限粘度［η］は0.56dl/gであった。実施例１と同様に成形後、物性測定を行った。得られたフィルムは、厚みムラが大きく、また表面外観が悪かったので、リターデーション値及び光透過率の測定が出来なかった。
【００５０】
比較例３
BCFLの代わりに、BFL ０．６３kgとBPA ３．８kgを用い、PTBPを４９g に変更し、Si1 を用いなかった以外は、実施例１と同様に反応重合を行った。
得られた重合体の極限粘度［η］は０．７３dl/gであった。実施例１と同様に成形後、物性測定を行った。
【００５１】
実施例１〜４および比較例１〜３の各試験後の物性を表１に示す。
【００５２】
【表１】

【００５３】
（表の説明）
（Ａ）共重合比：請求項１記載の一般式（Ａ）、（Ｂ）及び（Ｃ）の合計量に対する一般式（Ａ）の重量比（重量％）
極限粘度：0.5g／100ml ジクロロメタン樹脂溶液を20℃、ハギンズ定数0.45で極限粘度［η］(dl/g)を求めた。
フィルム厚み：デジタルマイクロノギスにて測定。
幅方向厚みムラ：１０ｍｍ間隔でフィルム厚みを幅方向に測定し、フィルム厚みのバラツキを示した。
リターデーション値：（株）溝尻光学工業製、自動エリプソメーター使用。
測定波長６３２．８ｎｍ。
Ｒｅ０：フィルム面に対し垂直方向からレーザー光を通過させ測定したリターデーション値。
Ｒｅ４５：フィルム面に対し垂直方向から４５°傾け、レーザー光を通過させ測定したリターデーション値。
光透過率：島津UV-240にて３５０〜７００ｎｍの光透過率の測定を行った。
成形性：フィルム成形品の外観を観察した。
成形機（板状品）：日精樹脂工業（株）製ＦＳ１２０Ｓ１８ＡＳＥを使用。
光線透過率及びヘーズ：村上色彩技術研究所製ＨＭ−１００を使用して、１９ｍｍφ透過光での光線透過率とヘーズを測定した。
【００５４】
【発明の効果】
本発明より、溶融押出法により安価で、かつ簡便にリターデーションの低い光学フィルムを製造することが可能であり、透明性、成形性などが良好なバランスのとれた光情報記録媒体用カバー層フィルムを作成できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical recording medium, and more particularly to an optical information recording medium on which a signal recording layer is irradiated with laser light through a light transmitting layer that transmits light, and information signals are recorded and / or reproduced. The present invention relates to a cover layer film for an optical information recording medium, characterized by comprising a polycarbonate having moldability and transparency suitable for production and having reduced birefringence.
[0002]
Bisphenol A polycarbonate is widely used as an optical material such as a retardation film, an optical disk substrate, and an optical disk cover layer film recently, taking advantage of its transparency, heat resistance, hydrolysis resistance, dimensional stability and the like. It became so. In particular, in recent years, various technologies have been developed that can record a large amount of information such as voice and moving images while the multimedia era is becoming popular, such as the broadcasting of high-definition digital video.
[0003]
To increase the capacity of optical discs, along with the adoption of a blue laser with a wavelength of about 400 nm, (1) multilayer optical disc technology that reads out multilayer information, and (2) special objective lenses with high NA (numerical aperture) and light transmission cover layer film A technique using a disk has been devised, and further, an optical disk technique for reading and writing information using near-field light has been devised.
However, when bisphenol A type polycarbonate is used for the cover layer film for optical recording media used in the multilayer optical disk technology for reading and writing multilayer information from one side, there are several problems.
[0004]
There are two methods for producing a film made of bisphenol A-type polycarbonate: a production method by a wet molding method using a solvent and a production method by a melt extrusion method. In the wet molding method using an organic solvent, there is no residual stress distortion of the obtained film, and birefringence (Δn) that changes the properties of incident light hardly occurs, and the retardation value [Δn × d, d = film An optically excellent film having a low thickness (nm)] can be obtained. However, since organic solvents are used, there are drawbacks such as solvent recovery equipment, expensive film formation equipment, rate of volatilization and diffusion of the solvent, and productivity decreases as the film becomes thicker. More expensive than film. In addition, the use of an organic solvent is unavoidable, and there is a problem that it may cause environmental pollution.
[0005]
On the other hand, in the melt extrusion method, since the film is formed while being stretched, residual stress strain is generated. When a film having such a property is used as an optical material, birefringence that changes the property of incident light remains, and an optically excellent film having a low retardation value cannot be obtained. It was.
[0006]
In a film produced by such a melt extrusion method, even if residual stress distortion occurs, by using bisphenol having a specific structure, it has low birefringence and optically excellent retardation value. As a method for obtaining a film, an optical sheet having a fluorene structure is disclosed (JP-A-7-179592 and JP-A-9-7222).
[0007]
However, the material described in JP-A-9-7222 increases the glass transition point and lowers the fluidity when the content of fluorenes is increased, so that sufficient fluorenes essential for suppressing the retardation value are sufficient. The retardation value cannot be sufficiently reduced. In addition, the material described in JP-A-7-179592 has been achieved by sufficiently introducing fluorenes essential for suppressing the retardation value, and is a material having a low retardation value. The film has a problem that the moldability is poor and thickness unevenness easily occurs, and the light transmittance of the film is not sufficient. Further, since a reaction mixture of hydroxyl alcohol and lactone is used as a molecular weight regulator, there is a drawback that the molecular weight of the obtained polymer tends to vary.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to produce an optical film having a low retardation value easily and inexpensively by a melt extrusion method, and an optical information recording medium having a good balance of transparency, moldability and the like. It is to provide a cover layer film.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the conventional problems, the present inventors have obtained a copolymer polycarbonate resin derived from specific two or three kinds of bisphenols, and the polycarbonate resin and a conventional bisphenol A type polycarbonate. The resin composition was found to be a high-quality optical film having both low birefringence, good transparency, moldability, etc., and the present invention was completed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
That is, the present invention comprises reacting a compound represented by general formula (A) and general formula (B), or general formula (A), general formula (B), and general formula (C) with a carbonate ester-forming compound. The general formula (B) is 20 to 60 wt% with respect to all monomer components [general formula (A) + general formula (B) + general formula (C)], and the intrinsic viscosity. [Η] is a cover layer film for an optical information recording medium made of a polycarbonate resin having 0.2 to 1.0 [dl / g].
[0011]
[Chemical formula 5]

(In the formula, R _{1 to} R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or 1 to 1 carbon atoms. 5 represents an alkoxy group, or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, (It can also have a C1-C5 alkoxy group.)
[0012]
[Chemical 6]

(In the formula, R _{5 to} R ₈ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or 1 to 5 carbon atoms. Or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, carbon R _{9 to} R ₁₂ may be hydrogen, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or carbon. An alkoxy group having 1 to 5 carbon atoms or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms It can also have a group and an alkoxy group having 1 to 5 carbon atoms. ₁₃ represents a mere bond or represents an aliphatic group having 1 to 6 carbon atoms .X _{is, -SiO (R 14) (R} 15) - and / or _{-SiO (R 16) (R 17} ) - the homo- Represents a polymer, a block copolymer or a random copolymer, the degree of polymerization is 0 to 200, and R _{14 to} R ₁₇ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or 6 to 12 carbon atoms. An aryl group, an alkenyl group having 2 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, (It can also have a C1-C5 alkyl group, a C2-C5 alkenyl group, and a C1-C5 alkoxy group.)
[0013]
[Chemical 7]

(In the formula, R _{18 to} R ₁₉ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or 1 to 5 carbon atoms. An alkoxy group, an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or a carbon number It can also have 1 to 5 alkoxy groups, Y is
[Chemical 8]

Wherein R ₂₀ and R ₂₁ are each hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Or a group in which R ₂₀ and R ₂₁ are bonded together to form a carbocyclic or heterocyclic ring having 3 to 6 carbon atoms, and when these groups have a carbon atom, It can also have a C1-C5 alkyl group, a C2-C5 alkenyl group, and a C1-C5 alkoxy group. a represents an integer of 0 to 20. )
[0014]
The polycarbonate resin used for the cover layer film for optical information recording media of the present invention is the above general formula (A) and general formula (B), or general formula (A), general formula (B) and general formula (C). Can be produced by reacting the above compound with a carbonic acid ester forming compound, and known methods used for producing polycarbonates derived from bisphenol A, such as bisphenols and phosgene. Such a direct reaction (phosgene method) or a transesterification reaction (transesterification method) between bisphenols and bisaryl carbonate can be employed.
[0015]
Specific examples of the compound of the general formula (A) used in the present invention include 9,9-bis (4-hydroxy-2-methylphenyl) fluorene and 9,9-bis (4-hydroxy-3-methylphenyl). ) Fluorene, 9,9-bis (4-hydroxyphenyl) fluorene, 3,6-dimethyl-9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methoxy-4-hydroxyphenyl) Fluorene, 9,9-bis (3-ethoxy-4-hydroxyphenyl) fluorene, 9,9-bis (3-ethyl-4-hydroxyphenyl) fluorene, 4,5-dimethyl-9,9-bis (4- Hydroxyphenyl) fluorene, 9,9-bis (3-phenyl-4-hydroxyphenyl) fluorene, 3,6-dimethyl-9,9-bis (3-methyl-) - hydroxyphenyl) fluorene and 3,6-diphenyl-9,9-bis (4-hydroxyphenyl) can be given fluorene. Among these, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, and 9,9-bis (4-hydroxy-2-methylphenyl) fluorene are particularly preferable. preferable. Two or more of these compounds can be used in combination.
[0016]
Specific examples of the compound of the general formula (B) used in the present invention include the following.
[0017]
[Chemical 9]

[0018]
These can be used in combination of two or more. X preferably includes 1 to 100 dimethylsiloxanes or 1 to 100 diphenylsiloxanes, and random copolymers thereof. Among these, α, ω-bis [3- (o-hydroxyphenyl) propyl] polydimethyldiphenyl random copolymer siloxane and α, ω-bis [3- (o-hydroxyphenyl) propyl] polydimethylsiloxane are particularly preferable.
[0019]
Specific examples of the compound represented by formula (C) in the present invention include 4,4′-biphenyldiol, bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) ether, and bis (4-hydroxyphenyl). ) Sulfone, bis (4-hydroxy-3-methylphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ketone, 1,1-bis (4 -Hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A; BPA), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) ) Cyclohexane (bisphenol Z; BPZ), 2,2-bis (4-hydroxy-3-methylphenyl) propane (dimethylbisphenol A), 2,2-bis (4-hydroxy-3,5-dimethyl) Tilphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane (bisphenol AP; BPAP), bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4-hydroxy-3-allylphenyl) And propane, 3,3,5-trimethyl-1,1-bis (4-hydroxyphenyl) cyclohexane (trimethylbisphenol-Z; TMBPZ) and the like. These can be used in combination of two or more. Of these, 2,2-bis (4-hydroxyphenyl) propane is particularly preferred.
[0020]
Examples of the carbonic acid ester forming compound in the present invention include phosgene, bisallyl carbonate such as diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, and dinaphthyl carbonate. Can be mentioned. Two or more of these compounds can be used in combination.
[0021]
In the phosgene method and the transesterification method, the phosgene method is preferred in consideration of the reactivity of the compound of the general formula (A) and the compound of the general formula (B).
[0022]
In the former phosgene method, the compound of the general formula (A) and the compound of the general formula (B) or the compound of the general formula (A) and the general formula (B) in the present invention usually in the presence of an acid binder and a solvent. ) And a compound of general formula (C) are reacted with phosgene. Examples of the acid binder include pyridine and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Examples of the solvent include methylene chloride, chloroform, chlorobenzene, and xylene. Furthermore, in order to accelerate the polycondensation reaction, a catalyst such as a tertiary amine such as triethylamine is used, and for adjusting the polymerization degree, phenol, pt-butylphenol, p-cumylphenol, alkyl-substituted phenols, Monofunctional compounds such as alkyl hydroxybenzoates and alkyloxyphenols are added as molecular weight regulators. In addition, antioxidants such as sodium sulfite and hydrosulfite, phloroglucin, isatin bisphenol, 1,1,1-tris (4-hydroxyphenyl) ethane, α, α ', α "-tris (4 A small amount of a branching agent such as -hydroxyphenyl) -1,3,5-triisopropylbenzene may be added, and the reaction is usually in the range of 0 to 150 ° C., preferably 5 to 40 ° C. Although the reaction time depends on the reaction temperature, it is usually 0.5 minutes to 10 hours, preferably 1 minute to 2 hours, and it is desirable to maintain the pH of the reaction system at 10 or more during the reaction. .
[0023]
On the other hand, in the latter transesterification method, the compound of the general formula (A) and the compound of the general formula (B) or the compound of the general formula (A) and the compound of the general formula (B) and the general formula (C) in the present invention are used. Are mixed with bisaryl carbonate and reacted at high temperature under reduced pressure. At this time, monofunctional compounds such as phenol, pt-butylphenol, p-cumylphenol, alkyl-substituted phenols, alkyl hydroxybenzoates and alkyloxyphenols may be added as molecular weight regulators. The reaction is usually carried out at a temperature in the range of 150 to 350 ° C., preferably 200 to 300 ° C., and the degree of vacuum is preferably 1 mmHg or less at the end, and phenols derived from the bisaryl carbonate produced by the transesterification reaction Is distilled out of the system. The reaction time depends on the reaction temperature and the degree of reduced pressure, but is usually about 1 to 10 hours. The reaction is preferably performed in an atmosphere of an inert gas such as nitrogen or argon, and the reaction may be performed by adding an antioxidant or a branching agent as desired.
[0024]
When the phosgene method is employed in the present invention, the tertiary amine polymerization catalyst used is, for example, triethylamine, tri-n-propylamine, tri-n-butylamine, N, N′-dimethylcyclohexylamine, N, N′— There are diethylaniline, diethylaminopyridine, and the like, and triethylamine is preferable from the viewpoint of catalyst activity and washing removal. The addition amount of the polymerization catalyst is preferably 0.001 to 5 mol% with respect to all bisphenols used.
[0025]
When employing the phosgene method in the present invention, a small amount of a quaternary ammonium salt may be added in order to carry out the reaction efficiently. Specific examples include tetramethylammonium chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tetraethylammonium bromide, and tetra-n-butylammonium iodide. Among these, trimethylbenzylammonium chloride and triethylbenzylammonium chloride are exemplified. preferable. This quaternary ammonium salt is generally preferably used in an amount of 0.005 to 5 mol% based on the total bisphenol used.
[0026]
Further, when a molecular weight regulator is used in the present invention, monohydric phenol is particularly preferable, and specifically, phenol, butylphenol, octylphenol, nonylphenol, decanylphenol, tetradecanylphenol, heptadecanylphenol, octadecanylphenol. Alkyl-substituted phenols such as hydroxybenzoic acid butyl, hydroxybenzoic acid octyl, hydroxybenzoic acid nonyl, hydroxybenzoic acid decanyl, hydroxybenzoic acid heptadecanyl, etc. hydroxybenzoic acid alkyl esters; butoxyphenol, octyloxyphenol, nonyloxyphenol, deca Alkyloxyphenols such as nyloxyphenol, tetradecanyloxyphenol, heptadecanyloxyphenol, octadecanyloxyphenol, etc. Lumpur acids are exemplified. The addition amount of this molecular weight regulator is 0.1-50 mol% with respect to all the bisphenols. Preferably, it is 0.5 to 10 mol%.
[0027]
The polycarbonate resin of the present invention synthesized by these reactions is molded by known molding methods such as melt extrusion film molding, injection film molding, compression film molding, and wet film molding for molding as a cover layer film for optical information recording media. Although it is possible, it is desirable to be able to easily form a melt-extruded film so as to be formed as a cover layer film for an optical recording medium by melt-extrusion film molding, and the intrinsic viscosity is in the range of 0.2 to 1.0 dl / g. Preferably there is.
[0028]
The amount of the general formula (B) used is 20 with respect to the total amount of the general formula (A), the general formula (B), and the general formula (C) in consideration of the strength of the cover layer film for optical recording media. ~ 60% by weight is preferred. If the general formula (B) is less than 20% by weight, it becomes too rigid and brittle, and if it exceeds 60% by weight, the heat resistance necessary as a cover layer film for an optical recording medium is insufficient.
[0029]
The use of the general formula (C) can be used for improving various performances and reducing costs, but particularly when bisphenol A is used, the compatibility with the conventional bisphenol A-type polycarbonate is good and the recyclability. In addition, there is an advantage that the resin replacement property in other types of extruders is improved. Considering the retardation value of the cover layer film for optical recording media, the general formula (C) is preferably less than 50% by weight with respect to the total amount of the general formula (A) and the general formula (C). When the general formula (C) is 50% by weight or more with respect to the total amount of the general formula (A) and the general formula (C), the retardation value is remarkably deteriorated and becomes insufficient.
[0030]
The polycarbonate resin of the present invention is preferably highly purified as in the case of a polycarbonate resin that is a material for a conventional cover layer film for optical recording media. Specifically, dust having a diameter of 50 μm or more is substantially not detected, dust having a diameter of 0.5 to 50 μm is 3 × 10 ⁴ or less, inorganic and organic residual chlorine is 2 ppm or less, residual alkali metal is 2 ppm or less, residual hydroxyl group Refinement is performed so as to satisfy the criteria of 200 ppm or less, residual nitrogen amount of 5 ppm or less, and residual monomer of 20 ppm or less as much as possible. In some cases, post-treatment such as extraction is performed to remove low molecular weight substances or solvents. Moreover, it is preferable to use a material in which impurities, isomers, and the like are reduced as much as possible for the compounds of the general formula (A), the general formula (B), the general formula (C), and the carbonic acid ester forming compound.
[0031]
The polycarbonate resin of the present invention ensures hindered phenolic and phosphite antioxidants; silicon-based, fatty acid esters as required in order to ensure the stability and releasability required when forming a cover layer film for optical recording media. Lubricants and mold release agents such as natural fats and oils such as fatty acids, fatty acid glycerides, fatty acid glycerides, beeswax, etc .; light stabilizers such as benzotriazole, benzophenone, dibenzoylmethane, salicylate; polyalkylene glycol, fatty acid glycerides, etc. An inhibitor or the like may be used in combination as appropriate.
[0032]
Furthermore, for the purpose of cost reduction or the like, the polycarbonate resin of the present invention and the conventional bisphenol A type polycarbonate can be arbitrarily mixed and used within a range not impairing the performance.
[0033]
When the cover layer film for optical recording media using the polycarbonate resin of the present invention is usually formed by melt extrusion film forming, it is preferably formed in the range of 230 to 380 ° C., and the melt viscosity is increased. It is preferably 1 × 10 ⁻² ml / sec or more of a tester (280 ° C., 15.7 MPa, nozzle diameter 1 mm × 10 mm). If it is less than 1 × 10 ⁻² ml / sec, extrusion is difficult because the melt viscosity is too large, and it is preferable to adjust the molding temperature and molecular weight to obtain fluidity that can be molded within a range that does not impair the physical properties.
[0034]
The cover layer film for an optical recording medium of the present invention is in contact with the recording surface via an adhesive layer, but is not only used outside the recording medium but also between the multilayered recording surface. it can. The film used here needs to transmit optical input / output signals faithfully, and optical isotropy is required. Therefore, the film is several tens from the direction perpendicular to the film surface and from the direction perpendicular to the film surface. A retardation value of 20 nm or less, preferably 10 nm or less, for light passing through a single path from a tilted direction. Further, the variation of the retardation value in the film is preferably 5 nm or less.
[0035]
The thickness of the cover layer film for an optical recording medium of the present invention is 20 to 200 μm, preferably 50 to 150 μm, more preferably 60 to 100 μm.
[0036]
The light transmittance of the cover layer film for optical recording media of the present invention is required to be 70% or more in the region of 350 to 700 nm in order to faithfully transmit optical input / output signals, preferably 80%. More preferably, it is 85% or more.
[0037]
The cover layer film for an optical recording medium of the present invention is not only a multilayer disk having a two-dimensional recording surface, but also a fluorescent multilayer disk that reads three-dimensional fluorescence emitted by chemical substances in holes and grooves of the disk. Can also be used.
[0038]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[0039]
Example 1
To 49 liters of 8.8% (w / v) aqueous sodium hydroxide solution, 3.5 kg of 9,9-bis (4-hydroxy-3-methylphenyl) fluorene (hereinafter abbreviated as BCFL) and 10 g of hydrosulfite were dissolved. . To this was added 25 liters of methylene chloride, and 2.3 kg of phosgene was blown in over 30 minutes while stirring at 15 ° C.
After completion of the blowing, the reaction solution is emulsified by stirring vigorously for 1 minute, and 84 g of p-tertiarybutylphenol (hereinafter abbreviated as PTBP) and 3.5 kg of the following polysiloxane compound (hereinafter abbreviated as Si1) are added. After stirring for 20 minutes, 20 ml of triethylamine was added, and stirring was continued for further 60 minutes for polymerization.
The polymerization solution was separated into an aqueous phase and an organic phase, the organic phase was neutralized with phosphoric acid, and washed repeatedly with water until the conductivity of the washing solution became 10 μS / cm 2 or less to obtain a purified resin solution. The obtained purified resin solution was filtered through a 0.5 μm-diameter Teflon filter, and then the resin solution was slowly added dropwise to 60 ° C. pure water that was vigorously stirred to solidify the polymer while removing the solvent. The solid was filtered and dried to obtain a white powdery polymer.
This polymer had an intrinsic viscosity [η] at a temperature of 20 ° C. (Haggins constant of 0.45) of a 0.5 g / dl solution containing methylene chloride as a solvent, and was 0.38 dl / g.
[0040]
[Chemical Formula 10]

[0041]
300 ppm of stearic acid monoglyceride was added to the obtained polycarbonate powder, and the mixture was extruded at 280 ° C. with a vented 50 mm extruder equipped with a 50 μm polymer filter to form a melt pellet.
[0042]
The obtained pellets were extruded at 280 ° C. with a melt film extruder equipped with a three-sided mirror finish roll to obtain a 150 mm wide melt-formed film. The obtained film was allowed to stand at room temperature for 2 days, and then the thickness of the film, thickness unevenness in the width direction, retardation value at 633 nm, and light transmittance (wavelength 350 to 700 nm) were measured.
Further, a part of the obtained pellet was molded at a resin temperature of 300 ° C., a mold temperature of 100 ° C., a molding cycle of 50 seconds / sheet, and a 3 mm thick plate-shaped product was molded, and light transmittance and haze were measured. Went.
[0043]
Example 2
Instead of Si1, the following polysiloxane compound was changed to 2.3 kg (hereinafter abbreviated as Si2), PTBP was changed to 48 g, and 0.5 g of triethylbenzylammonium chloride was added simultaneously with the addition of BCFL. A polymerization reaction was performed.
The intrinsic viscosity [η] of the obtained polymer was 0.28 dl / g. The physical properties were measured after molding in the same manner as in Example 1.
[0044]
Embedded image

[0045]
Example 3
A polymerization reaction was carried out in the same manner as in Example 1 except that the polysiloxane compound was changed to 3.5 kg (hereinafter abbreviated as Si3) instead of Si1 and changed to 48 g (hereinafter abbreviated as PH) of phenol instead of PTBP.
The intrinsic viscosity [η] of the obtained polymer was 0.29 dl / g. The physical properties were measured after molding in the same manner as in Example 1.
[0046]
Embedded image

[0047]
Example 4
Example 1 except that BCFL was changed to 2.5 kg, Si1 was changed to 1.8 kg, and 0.62-kg of 2,2-bis (4-hydroxyphenyl) propane (hereinafter abbreviated as BPA) was added simultaneously with the introduction of BCFL. The polymerization reaction was carried out in the same manner as above.
The intrinsic viscosity [η] of the obtained polymer was 0.35 dl / g. The physical properties were measured after molding in the same manner as in Example 1.
[0048]
Comparative Example 1
Physical properties were measured after molding in the same manner as in Example 1 except that a commercially available bisphenol A-type polycarbonate resin (Iupilon S-2000 manufactured by Mitsubishi Gas Chemical Co., Inc.) was used instead of the polycarbonate of Example 1.
[0049]
Comparative Example 2
Instead of BCFL, 2.6 kg of 9,9-bis (4-hydroxyphenyl) fluorene (hereinafter abbreviated as BFL) and 2.5 kg of BPA are used, and a reaction product of m-hydroxybenzyl alcohol and caprolactone (mol) instead of PTBP. Ratio 1/20) was changed to 2.0 kg, and reactive polymerization was carried out in the same manner as in Example 1 except that Si1 was not used.
The intrinsic viscosity [η] of the obtained polymer was 0.56 dl / g. The physical properties were measured after molding in the same manner as in Example 1. The obtained film had large thickness unevenness and poor surface appearance, so that the retardation value and light transmittance could not be measured.
[0050]
Comparative Example 3
Reaction polymerization was carried out in the same manner as in Example 1 except that 0.63 kg of BFL and 3.8 kg of BPA were used instead of BCFL, PTBP was changed to 49 g, and Si1 was not used.
The intrinsic viscosity [η] of the obtained polymer was 0.73 dl / g. The physical properties were measured after molding in the same manner as in Example 1.
[0051]
The physical properties after each test of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.
[0052]
[Table 1]

[0053]
(Explanation of the table)
(A) Copolymerization ratio: Weight ratio (% by weight) of the general formula (A) to the total amount of the general formulas (A), (B) and (C) according to claim 1
Intrinsic viscosity: 0.5 g / 100 ml The intrinsic viscosity [η] (dl / g) of a dichloromethane resin solution was determined at 20 ° C. and a Huggins constant of 0.45.
Film thickness: measured with a digital micro caliper.
Width-direction thickness unevenness: The film thickness was measured in the width direction at intervals of 10 mm, and showed variations in film thickness.
Retardation value: manufactured by Mizojiri Optical Co., Ltd., using an automatic ellipsometer.
Measurement wavelength 632.8 nm.
Re0: Retardation value measured by passing laser light from a direction perpendicular to the film surface.
Re45: Retardation value measured by passing a laser beam at an angle of 45 ° with respect to the film surface.
Light transmittance: The light transmittance of 350 to 700 nm was measured with Shimadzu UV-240.
Formability: The appearance of the film molded product was observed.
Molding machine (plate-shaped product): FS120S18ASE manufactured by Nissei Plastic Industry Co., Ltd. is used.
Light transmittance and haze: The light transmittance and haze at 19 mmφ transmitted light were measured using HM-100 manufactured by Murakami Color Research Laboratory.
[0054]
【The invention's effect】
According to the present invention, a cover layer film for an optical information recording medium that is inexpensive and can be easily produced by a melt extrusion method, and that has a good balance of transparency, moldability, etc. Can be created.

Claims (13)

A polycarbonate obtained by reacting a compound represented by the general formula (A) and the general formula (B) or the general formula (A), the general formula (B), and the general formula (C) with a carbonate-forming compound. The general formula (B) is 20 to 60 wt% with respect to all monomer components [general formula (A) + general formula (B) + general formula (C)], and the intrinsic viscosity [η] is 0 A cover layer film for an optical information recording medium comprising a polycarbonate resin of 2 to 1.0 [dl / g].

(In the formula, R _{1 to} R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or 1 to 1 carbon atoms. 5 represents an alkoxy group, or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, (It can also have a C1-C5 alkoxy group.)

(In the formula, R _{5 to} R ₈ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or 1 to 5 carbon atoms. Or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, carbon R _{9 to} R ₁₂ may be hydrogen, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or carbon. An alkoxy group having 1 to 5 carbon atoms or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms It can also have a group and an alkoxy group having 1 to 5 carbon atoms. ₁₃ represents a mere bond or represents an aliphatic group having 1 to 6 carbon atoms .X _{is, -SiO (R 14) (R} 15) - and / or _{-SiO (R 16) (R 17} ) - the homo- Represents a polymer, a block copolymer or a random copolymer, the degree of polymerization is 0 to 200, and R _{14 to} R ₁₇ are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or 6 to 12 carbon atoms. An aryl group, an alkenyl group having 2 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, (It can also have a C1-C5 alkyl group, a C2-C5 alkenyl group, and a C1-C5 alkoxy group.)

(In the formula, R _{18 to} R ₁₉ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or 1 to 5 carbon atoms. An alkoxy group, an aralkyl group having 7 to 17 carbon atoms, and when these groups have a carbon atom, as a substituent, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or a carbon number It can also have 1 to 5 alkoxy groups, Y is

Wherein R ₂₀ and R ₂₁ are each hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Or a group in which R ₂₀ and R ₂₁ are bonded together to form a carbocyclic or heterocyclic ring having 3 to 6 carbon atoms, and when these groups have a carbon atom, It can also have a C1-C5 alkyl group, a C2-C5 alkenyl group, and a C1-C5 alkoxy group. a represents an integer of 0 to 20. ) The general formula (A) is 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, and 9,9-bis (4-hydroxy-2- The cover layer film for an optical information recording medium according to claim 1, which is at least one selected from the group of (methylphenyl) fluorene. The cover layer film for an optical information recording medium according to claim 1, wherein the carbonic acid ester forming compound is phosgene. The cover layer film for an optical information recording medium according to claim 1, wherein R _{9 to} R _{12 in} the general formula (B) are at least one selected from a methyl group and a phenyl group. Random copolymer of dimethylsiloxane and diphenylsiloxane having a 3- (o-hydroxyphenyl) propyl group at the α, ω position and α, ω-bis [3- (o-hydroxyphenyl) propyl The cover layer film for an optical information recording medium according to claim 1, wherein the cover layer film is at least one selected from the group of polydimethylsiloxane. The cover layer film for an optical information recording medium according to claim 1, wherein the general formula (C) is 2,2-bis (4-hydroxyphenyl) propane. 2. The optical information recording medium according to claim 1, wherein the ratio of the general formula (C) is a weight ratio and the value of the general formula (C) / [general formula (A) + general formula (C)] is 0.5 or less. Cover layer film. The cover layer film for an optical information recording medium according to claim 1, wherein a polycarbonate resin composition comprising a mixture of the polycarbonate resin according to claim 1 and a polycarbonate resin derived from 2,2-bis (4-hydroxyphenyl) propane is used. 2. The cover layer film for an optical information recording medium according to claim 1, wherein the polycarbonate film is a film formed by a melt extrusion method. The cover layer film for an optical information recording medium according to claim 1, wherein the polycarbonate film has a retardation value at a reading light wavelength of 20 nm or less. The cover layer film for an optical information recording medium according to claim 1, wherein the polycarbonate film has a thickness of 20 to 200 μm. 2. The cover layer film for an optical information recording medium according to claim 1, wherein the light transmittance of the 100 [mu] m thick film of polycarbonate is 70% or more in a wavelength range of 350 nm to 700 nm. The cover layer film for an optical information recording medium according to claim 1, which is used for an optical recording medium for reading and writing information using near-field light.