JP2006188544A - Heat-resistant optical material and medium for optical transmission using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical material with heat resistance and signal transmission capability combinedly, utilizable as a core material for a medium for optical transmission, concretely, a plastic optical fiber or a waveguide type device. <P>SOLUTION: This optical material comprises a polymer having alicyclic hydrocarbon moieties on the side chains and a heat deformation temperature of ≥115°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

【００１８】
（式中、ＸはＨ、ＣＨ₃、Ｆ、ＣｌおよびＣＦ₃よりなる群から選ばれる少なくとも１種；Ｚは脂環式炭化水素部位を有する炭素数３〜３０の１価の有機基）で示される単量体の少なくとも１種に由来する構造単位、
構造単位Ａは式（１）の単量体と共重合可能な単量体の少なくとも１種に由来する構造単位］で示され、構造単位Ｍ１を１〜１００モル％および構造単位Ａを０〜９９モル％含む重合体からなるものである。
【００１９】
本発明の式（Ｍ−１）の重合体は、側鎖中に脂環式炭化水素部位を有した式（１）のアクリル系単量体由来の構造単位（Ｍ１）を必須成分とする重合体であり、脂環式炭化水素を側鎖に導入することで、可視領域の光に対して透明で、かつ高いガラス転移温度となるため、耐熱性光学材料として好ましいものである。
【００２０】
さらに、上記重合体の熱変形温度が１１５℃以上であり、７０℃以上といった高温環境下でも利用可能な光学材料、例えば車載ＬＡＮ用プラスチック光ファイバーに有用な材料となる。
【００２１】
【発明の実施の形態】
本発明の式（Ｍ−１）の重合体において必須成分である構造単位Ｍ１は、一般式（Ｍ−２）
−［Ｍ１−１］−［Ｍ１−２］− （Ｍ−２）
［式中、
構造単位Ｍ１−１は式（２）：
【００２２】
【化７】

【００２３】
（式中、Ｚ¹は脂環式炭化水素部位を有する炭素数３〜３０の１価の有機基）で示される単量体の少なくとも１種に由来する構造単位、
構造単位Ｍ１−２は式（３）：
【００２４】
【化８】

【００２５】
（式中、Ｘ³は、Ｈ、ＣＨ₃、ＣｌおよびＣＦ₃よりなる群から選ばれる少なくとも１種；Ｚ²は脂環式炭化水素部位を有する炭素数３〜３０の１価の有機基）で示される単量体の少なくとも１種に由来する構造単位］で示され、構造単位Ｍ１−１を１〜９９モル％および構造単位Ｍ１−２を１〜９９モル％含む構造単位であることが好ましい。
【００２６】
本発明の好ましい重合体の第１は、上記Ｍ１−１が１〜９９モル％、構造単位Ｍ１−２が１〜９９モル％、式（Ｍ−１）における任意の構造単位Ａが０〜９８モル％の重合体（Ｍ−２）である。
【００２７】
つまり、脂肪族脂環式炭化水素部位を側鎖に有するα−フロロアクリレート由来の構造単位Ｍ１−１と式（１）の単量体のうち式（２）で示されるα−フロロアクリレート以外の単量体由来の構造単位Ｍ１−２を必須成分として有する重合体であり、構造単位Ｍ1−1を導入することで耐熱性と機械的強度、特に曲げ強度、さらには可とう性を付与できる。
【００２８】
また構造単位Ｍ1−２を導入することで耐熱性と透明性を付与でき、さらには屈折率の調整（例えば高屈折率化によりＰＭＭＡ以上に設定）が可能である。
【００２９】
構造単位Ｍ1−２は式（２）のＸがＣＨ₃であるメタクリレート由来の構造単位であることが特に好ましく、上記と同様の耐熱性と透明性および屈折率の調整機能をさらに効果的に付与できる。
【００３０】
構造単位Ｍ１−１とＭ１−２の存在比率は、Ｍ１−１を１〜９９モル％、構造単位Ｍ１−２を１〜９９モル％含むものであれば良いが、Ｍ１−１＋Ｍ１−２＝１００モル％としたとき、好ましくはＭ１−１／Ｍ１−２が１０／９０〜９５／５モル％比、より好ましくは２５／７５〜９０／１０モル％比、特に好ましくは４０／６０〜９０／１０モル％比、さらに好ましくは４５／５５〜９０／１０モル％比である。
【００３１】
また本発明の式（Ｍ−１）または（Ｍ−２）の重合体において任意成分である構造単位Ａは、式（Ｍ−３）：
−［Ａ−１］−［Ａ−２］− （Ｍ−３）
［式中、
構造単位Ａ−１は式（４）：
【００３２】
【化９】

【００３３】
（式中、Ｘ¹はＨ、ＣＨ₃、Ｆ、ＣｌおよびＣＦ₃よりなる群から選ばれる少なくとも１種；Ｒ¹は水素原子、炭素数１〜３０の直鎖または分岐状のエーテル結合を含んでいても良いアルキル基および炭素数１〜３０の直鎖または分岐状のエーテル結合を含んでいても良い含フッ素アルキル基よりなる群から選ばれる少なくとも１種）で示される単量体の少なくとも１種に由来する構造単位および／または式（５）：
【００３４】
【化１０】

【００３５】
（式中、Ｘ²は前記式（４）のＸ¹と同じ；Ｒ²は芳香環を含む炭素数６〜３０の１価の炭化水素基であって、ただしＲ²中の水素原子の一部または全てがフッ素原子に置換されていても良い）で示される単量体の少なくとも１種に由来する構造単位；構造単位Ａ−２は式（１）、（４）および（５）に示される単量体と共重合可能な単量体由来の構造単位］で示され、重合体中に構造単位Ａ−１を１〜９９モル％および構造単位Ａ−２を０〜９８モル％含む構造単位であることが好ましい。
【００３６】
本発明の好ましい重合体の第２は、前記式（Ｍ−１）における側鎖に脂環式炭化水素部位を有する構造単位Ｍ１を１〜９９モル％、上記脂環式炭化水素部位を含まない構造単位Ａ−１を１〜９９モル％、さらには任意の構造単位Ａ−２を０〜９８モル％含む重合体（Ｍ−３）である。
【００３７】
式（４）の単量体に由来する構造単位を導入することで、機械的特性や透明性を付与でき、さらには屈折率の調整（例えば高屈折率化によりＰＭＭＡ以上に設定）が可能である。
【００３８】
式（５）の単量体に由来する構造単位を導入することで、さらなる耐熱性や機械的特性、低吸水性を付与でき、さらには屈折率の調整（例えば高屈折率化によりＰＭＭＡ以上に設定）が可能である。
【００３９】
構造単位Ａ−１においてＸ¹、Ｘ²がＣＨ₃であるメタクリレート由来の構造単位であるときは、耐熱性と透明性および屈折率の調整機能をさらに効果的に付与できる点で好ましい。
【００４０】
また、構造単位Ａ−１においてＸ¹、Ｘ²がＦ原子であるα−フロロアクリレート由来の構造単位であるときは、耐熱性と機械的強度、特に曲げ強度、さらには可とう性を付与できる点で好ましい。
【００４１】
つまり、構造単位Ａ−１はなかでも、メチルメタクリレートまたはメチル−αフロロアクリレートから選ばれる少なくとも１種の単量体由来の構造単位であることが好ましく、機械的特性や透明性を付与できる。
【００４２】
また構造単位Ａ−１はフェニルメタクリレートおよびフェニル−α−フロロアクリレートから選ばれる少なくとも１種の単量体由来の構造単位であるときは、さらなる耐熱性と低吸水性を付与できる点で好ましい。
【００４３】
構造単位Ｍ１とＡ−１の存在比率は、Ｍ１を１〜９９モル％、構造単位Ａ−１を１〜９９モル％含むものであれば良いが、Ｍ１＋Ａ−１＝１００モル％としたとき、好ましくはＭ１／Ａ−１が５／９５〜９０／１０モル％比、より好ましくは５／９５〜６０／４０モル％比、特に好ましくは１０／９０〜５０／５０モル％比、さらに好ましくは１０／９０〜４０／６０モル％比である。
【００４４】
本発明の式（Ｍ−１）および（Ｍ−３）において式（１）の単量体由来の構造単位Ｍ１におけるＸはなかでもＦ原子であることが好ましく、それによって、耐熱性と機械的強度、特に曲げ強度、さらには可とう性を付与できる。
【００４５】
本発明の式（Ｍ−１）、（Ｍ−３）の重合体における側鎖を形成するＺ、式（Ｍ−２）の重合体における側鎖を形成するＺ¹、Ｚ²は炭素数３〜３０の有機基であってその中に脂環式の炭化水素部位を有しているものである。
【００４６】
脂環式の炭化水素部位は単環構造の炭化水素部位であっても、複環構造の炭化水素部位であっても、それらいずれをも含む炭化水素部位であっても良い。
【００４７】
脂環式の炭化水素部位は単環構造の炭化水素部位を含む場合、Ｚ、Ｚ¹、Ｚ²は炭素数７以上の有機基であることが好ましく、それによってより効果的に耐熱性を付与できる。
【００４８】
特に、前記Ｚ、Ｚ¹、Ｚ²は複環構造の炭化水素部位を含む有機基であることが好ましく、より効果的に耐熱性と透明性を付与できる。
【００４９】
単環構造の炭化水素部位を含む場合の前記Ｚ、Ｚ¹、Ｚ²は、具体的には、
（１）シクロペンチル基およびその誘導体を有する有機基、
（２）シクロヘキシル基およびその誘導体を有する有機基、
（３）パーヒドロビフェニル基およびその誘導体を有する有機基、
（４）スピロ〔４，４〕ノナンおよびその誘導体を有する有機基、
（５）スピロ〔４，５〕デカンおよびその誘導体を有する有機基
などが好ましくあげられ、それらの一部の例として、
【００５０】
【化１１】

【００５１】
などがあげられる。
【００５２】
またこれら例示の炭化水素基の水素原子を炭素数１〜５のアルキル基やフッ素原子、さらには官能基などで置換したものであっても良い。
【００５３】
複環構造の炭化水素部位を含む場合の前記Ｚ、Ｚ¹、Ｚ²は、具体的には、
（６）アダマンタンおよびその誘導体を有する有機基、
（７）ノルボルナンおよびその誘導体を有する有機基、
（８）パーヒドロアントラセンおよびその誘導体を有する有機基、
（９）パーヒドロナフタレンおよびその誘導体を有する有機基、
（１０）トリシクロ〔５．２．１．０^2,6 〕デカンおよびその誘導体を有する有機基
などがあげられ、それらの一部の例として、
【００５４】
【化１２】

【００５５】
などがあげられる。
【００５６】
またこれら例示の炭化水素基の水素原子を炭素数１〜５のアルキル基やフッ素原子、さらには官能基などで置換したものであっても良い。
【００５７】
さらにこれら複環構造の炭化水素部位を含む有機基のうち、アダマンタンおよびその誘導体、ノルボルナンおよびその誘導体、トリシクロ〔５．２．１．０^{2, 6} 〕デカンおよびその誘導体を含むものが好ましく、これらは特に耐熱性と透明性を効果的に重合体に付与できる。
【００５８】
本発明の式（Ｍ−１）、（Ｍ−２）および（Ｍ−３）の重合体において、側鎖に脂環式構造の炭化水素部位を有する構造単位を形成できる単量体（式（１）、（２）および（３））は具体的には、前記Ｚ、Ｚ¹、Ｚ²から選ばれる少なくとも１種の側鎖構造を有するアクリル系単量体であり、例えばつぎのものが例示できる。
【００５９】
（Ｉ）ノルボルナンおよびその誘導体を含む有機基を側鎖に有する単量体
【００６０】
【化１３】

【００６１】
（式中、ＸはＨ、Ｆ、Ｃｌ、ＣＨ₃またはＣＦ₃；Ｒ^1a、Ｒ^2a、Ｒ^3a、Ｒ^4a、Ｒ^5a、Ｒ^6a、Ｒ^7a、Ｒ^8a、Ｒ^9a、Ｒ^10aは同じかまたは異なり、Ｈ、Ｆ、Ｃｌまたは炭素数１〜１４のハロゲン原子で置換されていてもよいアルキル基；Ｒ^11aは結合手または分岐鎖を含んでいてもよい炭素数１〜６のアルキレン基；ｎは０、１〜２の整数）
より具体的には、
【００６２】
【化１４】

【００６３】
などがあげられる。
【００６４】
（II）アダマンタンおよびその誘導体を含む有機基を側鎖に有する単量体
【００６５】
【化１５】

【００６６】
または
【００６７】
【化１６】

【００６８】
（式中、ＸはＨ、Ｆ、Ｃｌ、ＣＨ₃、ＣＦ₃；Ｒ^1b、Ｒ^2bは環に結合した置換基であり、ＣＨ₃、Ｃ₂Ｈ₅またはＯＨ；Ｒ^4b、Ｒ^5bは結合手または分岐鎖を有していてもよい炭素数１〜６のアルキレン基；Ｒ^3bはＨ、ＣＨ₃またはＣ₂Ｈ₅；ｎは０または１〜２の整数）などがあげられ、より具体的には、
【００６９】
【化１７】

【００７０】
などがあげられる。
【００７１】
（III）トリシクロ〔５．２．１．０^2,6 〕デカンおよびその誘導体を含む有機基を側鎖に有する単量体
【００７２】
【化１８】

【００７３】
（式中、ＸはＨ、Ｆ、Ｃｌ、ＣＨ₃またはＣＦ₃；Ｒ^1c、Ｒ^2c、Ｒ^3c、Ｒ^4c、Ｒ^5c、Ｒ^6c、Ｒ^7c、Ｒ^8c、Ｒ^9c、Ｒ^10c、Ｒ^11c、Ｒ^12c、Ｒ^13c、Ｒ^14c、Ｒ^15cは同じかまたは異なり、Ｈ、Ｆ、Ｃｌまたはハロゲン原子で置換されていてもよい炭素数１〜１４のアルキル基；Ｒ^16cは結合手または分岐鎖を含んでいてもよい炭素数１〜６のアルキレン基）
【００７４】
【化１９】

【００７５】
（式中、ＸはＨ、Ｆ、Ｃｌ、ＣＨ₃またはＣＦ₃；Ｒ^1d、Ｒ^2d、Ｒ^3d、Ｒ^4d、Ｒ^5d、Ｒ^6d、Ｒ^7d、Ｒ^8d、Ｒ^9d、Ｒ^10d、Ｒ^11d、Ｒ^12d、Ｒ^13dは同じかまたは異なり、Ｈ、Ｆ、Ｃｌまたはハロゲン原子で置換されていてもよい炭素数１〜１４のアルキル基；Ｒ^14dは結合手または分岐鎖を含んでいてもよい炭素数１〜６のアルキレン基）
より具体的には、
【００７６】
【化２０】

【００７７】
などがあげられる。
【００７８】
本発明の式（Ｍ−３）の重合体において、構造単位Ａ−１を形成する単量体の具体例としては、つぎのものが例示できる。
【００７９】
式（４）の鎖状の炭化水素基を側鎖に有する単量体の具体例としては、
【００８０】
【化２１】

【００８１】
（式中、ｎは１〜６の整数、ｍは０〜２９までの整数を示す。またＹはＨもしくはＦ；Ｒ^1e、Ｒ^2e、Ｒ^3eは同じか異なり、Ｈ、炭素数１〜２９のエーテル結合を含んでも良いアルキル基または炭素数１〜２９のエーテル結合を含んでも良い含フッ素アルキル基）
などがあげられる。
【００８２】
より具体的には
【００８３】
【化２２】

【００８４】
があげられ、なかでもメタクリル酸、α−フルオロアクリル酸、アクリル酸、メチルメタクリレート（ＭＭＡ）、メチル−α−フルオロアクリレートが透明性、耐熱性、機械的強度の向上効果に優れる点で好ましい。特にＭＭＡは光学特性、機械特性の向上効果に優れる。
【００８５】
式（５）の芳香環を含む炭化水素基を側鎖に有する単量体の具体例としては、
【００８６】
【化２３】

【００８７】
（式中、Ｘ²はＨ、Ｆ、Ｃｌ、ＣＨ₃、ＣＦ₃；Ｒ^1f、Ｒ^2f、Ｒ^3f、Ｒ^4f、Ｒ^5fは同じかまたは異なり、Ｈ、Ｆ、Ｃｌまたはハロゲン原子で置換されていてもよい炭素数１〜１４のアルキル基；Ｒ^6fは結合手または分岐鎖を有していてもよい炭素数１〜６のアルキレン基）などがあげられ、具体的には
【００８８】
【化２４】

【００８９】
が好ましくあげられる。
【００９０】
なかでも、フェニルメタクリレート、フェニルα−メタクリレートが耐熱性を向上させる点で好ましい。
【００９１】
本発明の耐熱性光学材料に用いる重合体の分子量は数平均分子量で２０００〜１００００００の範囲のものが通常使用され、好ましくは１００００〜５０００００、特に好ましくは５００００〜３０００００である。低すぎる分子量は機械的特性、特に曲げ強度が低下したり可とう性が低下する点で好ましくない。また、高すぎる分子量は成形性が低下したり、光散乱の増加に伴う透明性低下を惹き起こす点で好ましくない。
【００９２】
本発明の耐熱性光学材料に用いる重合体は熱変形温度で１１５℃以上であり、それによって高温の環境下でも軟化が抑えられ、その結果、光信号の散乱が低減でき良好な光信号の伝送（長距離において光信号の損失の少ない伝送）が可能になる。
【００９３】
本発明における熱変形温度とは荷重たわみ温度（ＨＤＴ）のことを言い、ＡＳＴＭ Ｄ６８４で規格化された方法にて測定した値を用いるものである。
特に、熱変形温度は１２０℃以上、特に１３０℃以上、さらには１４０℃以上のものが好ましく、熱変形温度が高いことにより、特にエンジン部分周辺に位置する自動車制御用や、航空機の制御用、産業用ロボットの制御用など高温の環境で利用する光学部品、光通信媒体、プラスチック光ファイバーなどに有利である。
【００９４】
本発明の耐熱性光学材料は可視領域の光に対して透明性が高いことが必要であり、特に６５０ｎｍの波長の光に対して透明性が高いことが望ましい。
【００９５】
この観点から、本発明の耐熱性光学材料は、６５０ｎｍ波長光での吸光係数で、０．０１５ｃｍ^-1以下であることが好ましく、特に０．０１４ｃｍ^-1以下、さらには０．０１３ｃｍ^-1以下であることが好ましい。それによって光信号の吸収損失を低減でき、２０ｍ〜１００ｍといった長距離の光信号の伝送においても損失を低減できる。
【００９６】
ここで吸光係数とは、適当な屈折率をもったクラッド材と溶融紡糸することにより、本発明の耐熱光学材料をコア材として、長さ１００ｍｍのプラスチック光ファイバーを作製し、波長６５０ｎｍでの光で透過光強度を測定する。入射光強度をＩ₀、透過光強度をＩ₁としたとき、吸光係数は下式により計算された値をいう。
吸光係数＝１／１０・ｌｏｇ（Ｉ₀／Ｉ₁）
【００９７】
本発明の耐熱性光学材料は広い範囲で屈折率を調整することが可能である。それによって、光伝送媒体に利用したり、またはクラッドに利用できる。
【００９８】
特に本発明の耐熱性光学材料は透明性が高く、高屈折率に調整可能であるため光伝送媒体、例えば、プラスチック光ファイバや光導波路型素子のコアに利用することができる。
【００９９】
その場合、本発明の耐熱性光学材料は屈折率：ｎ_Dで１．４５以上であることが好ましい。
【０１００】
屈折率は、ナトリウムＤ線を光源として２５℃においてアッベの屈折率計を用いて測定した値を用いるものである。
【０１０１】
屈折率は、１．４７以上、さらには１．４８以上であることが好ましく、最も好ましい範囲は１．４８〜１．５２である。屈折率が低すぎると、プラスチック光ファイバーを作製する際にクラッド材側の材料の選択が制約される点で好ましくない。屈折率が高すぎると、光散乱に基づく伝送損失が増大するほか、プラスチック光ファイバーの接合時に結合損失が増大する点で好ましくない。
【０１０２】
以上に構造単位および物性（特性）の観点から説明をしてきたが、つぎに本発明の耐熱性光学材料に使用する重合体の好ましい具体例を説明する。
【０１０３】
重合体（Ｉ）
式（Ｍ−４）：
−［Ｍ１−１ａ］−［Ａ−１ａ］− （Ｍ−４）
[式中、構造単位Ｍ１−１ａは式（２−１）：
【０１０４】
【化２５】

【０１０５】
（式中、Ｚ³はアダマンタンおよびその誘導体、ノルボルナンおよびその誘導体、トリシクロ〔５．２．１．０^2,6 〕デカンおよびその誘導体から選ばれる少なくとも１種の複環構造の炭化水素部位を含む炭素数１０〜３０の１価の有機基）；構造単位Ａ−１ａはメチルメタクリレート由来の構造単位]であって、構造単位Ｍ１−１ａを１〜１００モル％、構造単位Ａ−１ａを０〜９９モル％含む重合体。
【０１０６】
この重合体は高い透明性と機械的強度、特に曲げ強度や可とう性に優れる点で好ましい。
【０１０７】
重合体（II）
式（Ｍ−５）：
−［Ｍ１−１ａ］−［Ａ−１ａ］−［Ａ−２ａ］− （Ｍ−５）
（式中、構造単位Ｍ１−１ａおよびＡ−１ａは前記式（Ｍ−４）と同じ；構造単位Ａ−２ａはフェニルメタクリレートまたはフェニル−α−フロロアクリレートに由来する構造単位）であって、構造単位Ｍ１−１ａを１〜９９モル％、構造単位Ａ−１ａを０〜９８モル％、構造単位Ａ−２ａを１〜９９モル％含む重合体。
【０１０８】
この重合体は優れた耐熱性と低い吸水性を有する点で好ましい。
【０１０９】
重合体（III）
式（Ｍ−６）：
−［Ｍ１−１ａ］−［Ｍ１−２ａ］−［Ａ−１ａ］− （Ｍ−６）
[式中、構造単位Ｍ１−１ａ、Ａ−１ａは前記式（Ｍ−４）と同じ；構造単位Ｍ１−２ａは式（３−１）：
【０１１０】
【化２６】

【０１１１】
（式中、Ｚ⁴はアダマンタンおよびその誘導体、ノルボルナンおよびその誘導体、トリシクロ〔５．２．１．０^2,6 〕デカンおよびその誘導体から選ばれる少なくとも１種の複環構造の炭化水素部位を含む炭素数１０〜３０の１価の有機基）］
であって、構造単位Ｍ１−１ａを１〜９９モル％、構造単位Ｍ１−２ａを１〜９９モル％、構造単位Ａ−１ａを０〜９８モル％含む重合体。
【０１１２】
この重合体は耐熱性および機械的強度、特に曲げ強度に優れ、さらに屈折率を調整しやすい点で好ましい。
【０１１３】
本発明の耐熱性光学材料を特にコアに用いる場合、耐熱性や信号の伝送性能を損なわない範囲で添加剤を混合しても良い。
【０１１４】
例えば、屈折率を調節するために、フタル酸ベンジル−ｎ−ブチル（屈折率：１．５７５）、１−メトキシフェニル−１−フェニルエタン（屈折率：１．５７１）、安息香酸ベンジル（屈折率：１．５６８）、ブロモベンゼン（屈折率：１．５５７）、ｏ−ジクロロベンゼン（屈折率：１．５５１）、ｍ−ジクロロベンゼン（屈折率：１．５４３）、１，２’−ジブロモエタン（屈折率：１．５３８）、３−フェニル−１−プロパノール（屈折率：１．５３２）、ジフェニルフタル酸（Ｃ₆Ｈ₄（ＣＯＯＣ₆Ｈ₅）₂）、トリフェニルフォスフィン（(Ｃ₆Ｈ₅)₃Ｐ）およびジベンジルフォスフェート（(Ｃ₆Ｈ₅ＣＨ₂Ｏ)₂ＰＨＯ₂）、４，４’−ジブロモベンジル、４，４’−ジブロモビフェニル、２，４’−ジブロモアセトフェノン、３’，４’−ジクロロアセトフェノン、３，４−ジクロロアニリン、２，４−ジブロモアニリン、２，６−ジブロモアニリン１，４−ジブロモベンゼン等の化合物などが添加できる。これらの低分子化合物は単純に本発明の耐熱性光学材料の屈折率を一様に調整するばかりではなく、例えば特開平８−１１０４２０号公報記載の屈折率分布（グレーデッドインデックス）型光ファイバーを得るためのドーパントとして機能する。本発明の耐熱性光学材料は、耐熱性の屈折率分布（グレーデッドインデックス）型光ファイバーを得るのにも有用な材料である。
【０１１５】
上記本発明の耐熱性光学材料は光伝送媒体、コアとクラッドで形成されるプラスチック光ファイバーのコア材に利用することが好ましい。
【０１１６】
本発明の耐熱性光学材料を用いた上記プラスチック光ファイバーは耐熱性が高いため、１００℃以上の耐熱が必要となる場合に有用である。例えば、ライトガイドにおいては、ハロゲン光源に接近してプラスチック光ファイバーを敷設する際に耐熱性が必要になる。センサー用途においては、例えば車のヘッドライト照明の検知や溶融プレス機の位置決めセンサー等、雰囲気が高温になる部分の検出の際に耐熱性が必要になる。産業用ロボットのセンサーも同様である。光通信用途においては、例えば車載ＬＡＮにおいて高温になるエンジンルーム内、車の天井部分、インストールドパネル等に配線する際には１００℃以上の耐熱性が必要となる。航空機に搭載される場合も同様である。ファクトリーオートメーション（ＦＡ）用途におけるプラスチック光ファイバー配線に関しても高温の環境に曝される場合、耐熱性が必要である。また、屋外にて使用する際や屋内であってもビルの屋上の配電盤室内や通信基地局等、通常の空調設備がない環境のため耐熱性が要求されている。本発明の耐熱性光学材料は、これらの用途に効果的に利用できる。
【０１１７】
これら、耐熱性光学材料を用いた上記プラスチック光ファイバーのクラッドに用いる光学材料はガラス転移温度が１００℃以上であって、屈折率（ｎ_D）が１．４４以下であることが好ましい。
【０１１８】
クラッドに用いる光学材料は、ガラス転移温度がなかでも１０５℃以上のものが好ましく、より好ましくは１１０℃以上、さらに好ましくは１２０℃、特に１３０℃以上のものである。ガラス転移温度が高いことにより耐熱性を向上させることができ、コアに用いる本発明の耐熱性光学材料と組合せて、高耐熱のプラスチック光ファイバーを構成できる点で好ましく、上記耐熱性を必要とする用途においてより一層効果的に利用できる。
【０１１９】
上記耐熱性クラッドとして用いる重合体の好ましいものは、屈折率１．４４以下の含フッ素アクリル系樹脂が通常用いられ、側鎖にフルオロアクリル基を有するメタクリレート、α−フロロアクリレートの（共）共重合体などが好ましい。その中でも耐熱性（高ガラス転移温度）と低屈折率を兼ね備えた含フッ素アクリレートとして式（６）：
【０１２０】
【化２７】

【０１２１】
（式中、Ｘ³はＨ、ＣＨ₃、Ｆ、ＣＦ₃またはＣｌ；Ｒｆ¹およびＲｆ²は同じかまたは異なり、炭素数１〜５のパーフルオロアルキル基；Ｗはフッ素原子で置換されていてもよい炭素数１〜５の炭化水素基）で示される構造単位（ａ）を有する重合体が好ましい。
【０１２２】
特に上記式（６）の構造単位とメチルメタクリレート由来の構造単位とからなる含フッ素共重合体が好ましく、例えば上記式（６）の構造単位（ａ）とメチルメタクリレート由来の構造単位（ｂ）の合計を１００としたとき（ａ）／（ｂ）３２／６８〜６４／３６モル％比とからなる含フッ素共重合体が好ましい。
【０１２３】
上記プラスチック光ファイバーの層構成は通常、内側よりコア層、クラッド層から構成される。口径には特に制限はないが、通常１２５μｍから１ｍｍ程度である。各層の厚さは通常、コア層／クラッド層＝９８／２程度でコア層がその大部分を占める。さらに外周に保護層があってもかまわない。この保護層は主として耐熱性の向上、曲げ損失の低減、耐衝撃性の向上の目的で用いられ、通常、フッ化ビニリデン系共重合体が用いられる。中でもフッ化ビニリデン／テトラフルオロエチレン共重合体が好ましい。保護層の厚さはクラッド層とほぼ同一である。また、光ファイバーケーブルとして使用する際にはさらにその外周に被覆層を配置する。被覆層としては従来から使用されているナイロン１２、ポリ塩化ビニル、ポリエチレン、ポリウレタン、ポリプロピレン等を用いることができる。
【０１２４】
前述の構成においてコア層が単一の屈折率からなるものはＳＩ（ステップインデックス）型プラスチック光ファイバーと呼ばれ、最も一般的である。
【０１２５】
コア層の屈折率が内周から外周に向かって階段状に屈折率が低下していくものをマルチステップ型プラスチック光ファイバーと呼ばれている。また、内周から外周に向かって屈折率がなめらかに低下していくものをＧＩ（グレーデッドインデックス）型プラスチック光ファイバーと呼ばれている。
【０１２６】
上記プラスチック光ファイバの作製方法としては、例えば、ＳＩ型プラスチック光ファイバーの場合、複合紡糸ノズルを用いてコア材ポリマーとクラッド材ポリマーを同心円状に配置し、溶融複合紡糸することでファイバー状に賦形し、ついで機械的強度の向上を目的として加熱下での延伸処理を行なう方法が一般的である。
【０１２７】
本発明の耐熱性光学材料は光導波路型素子のコアとしても好ましく用いることができ、コア材およびクラッド材として前述の同様な重合体の具体例が同様に好ましく例示できる。
【０１２８】
図１に、典型的な光導波路素子の要部構造を例示する。ここで、１は基板、２はコア部、３および４はクラッド部である。かかる光導波路素子は、光機能素子間を接続するために使用され、一方の光機能素子の端末から送出された光は、光導波路素子のコア部２内を、例えばコア部２とクラッド部３、４との界面で全反射を繰り返しながら、他方の光機能素子端末へと伝播される。光導波路素子の形式は、平面型、ストリップ型、リッジ型、埋込み型等の適宜の形式を採ることができる。
【０１２９】
光導波路素子は例えば、光通信信号に対し、スイッチング、増幅、波長変換、光合分波、波長選択等の作用を示す素子があり、光スイッチ、光ルーター、ＯＮＵ、メディアコンバーター等に利用できる。
【０１３０】
本発明の耐熱性光学材料は上記以外のその他の用途として、例えばレンズ（ピックアップレンズ、めがね用レンズ、カメラ用レンズ、プロジェクター用フレネルレンズ、コンタクトレンズ）、ＬＥＤ等の発光体用封止材、反射防止材、光ディスク基板、照明器具のカバー材、ディスプレイ保護板、透明ケース、表示板、自動車用部品等があげられる。
【０１３１】
【実施例】
つぎに、実施例をあげて本発明を具体的に説明するが、本発明は以下の実施例に限られるものではない。
【０１３２】
実施例１
２−メチル−２アダマンチルα−フルオロアクリレート３０ｇ、メチルメタクリレート（ＭＭＡ）７０ｇ、ｎ−ラウリルメルカプタン０．１ｇ、アゾイソブチロニトリル０．０２５ｇを５００ｍｌのガラス製フラスコ内で溶解混合し、脱気および窒素置換を繰り返し、密封した後、７０℃で１６時間重合させた。
【０１３３】
重合終了後、生成物にアセトン３００ｇを加えて溶解し、得られた溶液をメタノール５リットルに注ぎ込んだ。沈殿した重合物を液体から分離し、１００℃の温度で１０時間減圧乾燥し、固体状の重合体を９２ｇ（収率９２％）得た。
【０１３４】
得られた重合体を¹⁹ＦＮＭＲ、¹ＨＮＭＲおよびＩＲ法で測定し、２−メチル−２アダマンチルα−フルオロアクリレート／ＭＭＡ＝１５／８５（モル％）の共重合体であることを確認した。
【０１３５】
また、得られた共重合体の重量平均分子量、屈折率、ガラス転移温度、熱変形温度、メルトインデックス、吸光係数および引張強度を調べた。結果を表１に示す。
【０１３６】
なお、物性値の測定法は次の方法による。
（１）重量平均分子量（Ｍｗ）
ＧＰＣ法により測定する（ポリスチレン換算）。
【０１３７】
（２）屈折率（ｎ_D）
ナトリウムＤ線を光源として２５℃において（株）アタゴ光学機器製作所製のアッベ屈折率計を用いて測定する。
【０１３８】
（３）ガラス転移温度（Ｔｇ）
セイコー電子（株）製のＤＳＣ（示差走査熱量計）を用いて、１st runを昇温速度１０℃／分で２００℃まで上げ、２００℃で１分間維持したのち、降温速度１０℃／分で２５℃まで冷却し、ついで昇温速度１０℃／分で得られる２nd runの吸熱曲線の中間点をＴｇとする。
【０１３９】
（４）熱変形温度（ＨＤＴ）
（株）東洋精機製作所製のＨＤＴ試験装置を使用し、ＡＳＴＭ Ｄ６８４に準じて測定する。
【０１４０】
（５）メルトインデックス（ＭＩ）
（株）島津製作所製の降下式フローテスターを用い、各共重合体を内径９．５ｍｍのシリンダーに装着し、温度２３０℃で５分間保った後、７ｋｇのピストン荷重部に内径２．１ｍｍ、長さ８ｍｍのオリフィスを通して押し出し、１０分間に押し出された共重合体のグラム数で表わす。
【０１４１】
（６）吸光係数（ε）
重合体をコア材に、クラッド材として２，２，２−トリフルオロエチルメタクリレート５０重量％、２，２，３，３−テトラフルオロプロピルメタクリレート３０重量％、メチルメタクリレート２０重量％からなる共重合体を用い、２３０℃にて複合紡糸し、直径３００μｍ（クラッド材厚さ１５μｍ）、長さ１００ｍｍのプラスチック光学ファイバーを作製する。この光学ファイバーの波長６５０ｎｍでの光で透過度を測定する。入射光強度をＩ₀、透過光強度をＩ₁としたとき、吸光係数、εは下式により計算する。
ε＝１／１０・ｌｏｇ（Ｉ₀／Ｉ₁）
【０１４２】
（７）引張強度（Ｆ）
引張強度は（株）島津製作所製の万能試験機を用い、ＡＳＴＭ Ｄ６３８に準じて測定する。
【０１４３】
実施例２
単量体として、イソボルニルα−フルオロアクリレート１５ｇ、フェニルα−フルオロアクリレート１５ｇ、ＭＭＡ７０ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１４４】
実施例３
単量体として、トリシクロデカニルα−フルオロアクリレート４０ｇ、メチルα−フルオロアクリレートの６０ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様して測定した。結果を表１に示す。
【０１４５】
実施例４
単量体として、２−メチル−２アダマンチルα−フルオロアクリレート２５ｇ、イソボルニルメタクリレート２５ｇおよびＭＭＡ５０ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１４６】
実施例５
単量体として、シクロヘキシルα−フルオロアクリレート１５ｇ、フェニルα−フルオロアクリレート２５ｇおよびメチルα−フルオロアクリレート６０ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１４７】
比較例１
単量体として、ＭＭＡ１００ｇのみを用いた以外は実施例１と同様にしてＭＭＡの単独重合体を得た。得られた重合体の各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１４８】
比較例２
単量体として、フェニルメタクリレート３０ｇおよびＭＭＡ７０ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１４９】
比較例３
単量体として、２，２，２−トリフルオロエチルα−フルオロアクリレート２５ｇおよびＭＭＡ７５ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１５０】
比較例４
単量体として、２，２，３，３，３−ペンタフルオロプロピルα−フルオロアクリレートの５０ｇおよびフェニルメタクリレート５０ｇを用いた以外は実施例１と同様にして共重合体を得た。得られた共重合体の組成、および各種物性を実施例１と同様にして測定した。結果を表１に示す。
【０１５１】
【表１】

【０１５２】
合成例１
単量体として２，２−ビス（トリフルオロメチル）プロパニルメタクリレート５０ｇ、ＭＭＡ２０ｇ、および１Ｈ，１Ｈ，３Ｈ−テトラフルオロプロピルメタクリレート３０ｇを用いた以外は実施例１と同様にして重合体を得た。得られた重合体のガラス転移温度は１１０℃、ＭＩは３７ｇ／１０ｍｉｎ、屈折率は１．４１９であった。
【０１５３】
実施例６
コア材として実施例１の重合体をクラッド材として２，２，２−トリフルオロエチルメタクリレート５０重量％、２，２，３，３−テトラフルオロプロピルメタクリレート３０重量％、メチルメタクリレート２０重量％からなる共重合体を用い、２３０℃にて複合紡糸し、直径３００μｍ（鞘材厚さ１５μｍ）、長さ５０ｍのプラスチック光ファイバーを作製した。このプラスチック光ファイバーの伝送損失を２５ｍ−５ｍのカットバック法により入射ＮＡ＝０．１における波長６５０ｎｍの伝送損失を測定した。また、このプラスチック光ファイバーを１００℃で１６８時間保持し、その後の波長６５０ｎｍにおける伝送損失を同様に測定した。結果を表２に示す。
【０１５４】
実施例７
コア材として実施例４の重合体を用い、クラッド材として合成例１の重合体を用いた以外は実施例６と同様にしてプラスチック光ファイバーを得た。得られたプラスチック光ファイバーの特性を表２に示す。
【０１５５】
比較例５
コア材として比較例３の重合体を用いた以外は実施例６と同様にしてプラスチック光ファイバーを得た。得られたプラスチック光ファイバーの特性を表２に示す。
【０１５６】
【表２】

【０１５７】
【発明の効果】
本発明によれば、耐熱性と信号伝送能力を兼ね備えた光学材料を提供することができる。
【０１５８】
さらに光伝送用媒体、詳しくはプラスチック光ファイバーや導波路型素子のコア用材料として利用可能な信号伝送能力を有する光学材料、特に、自動車のエンジンルームで要求される１２５℃の環境、またはディーゼル車のエンジンルームで要求される１５０℃の環境で利用可能な光学材料を用いてなるプラスチック光ファイバーを提供できる。
【図面の簡単な説明】
【図１】光導波路素子の要部構造の概略断面図である。
【符号の説明】
１ 基板
２ コア部
３ クラッド部
４ クラッド部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical material excellent in heat resistance in addition to optical characteristics. The optical material of the present invention is suitable, for example, as an optical transmission medium, specifically as a core material for plastic optical fibers and waveguide elements.
[0002]
[Prior art]
Conventionally, acrylic resin, polycarbonate, amorphous polyolefin, and the like have been used as plastic optical materials.
[0003]
Acrylic resins, particularly polymethyl methacrylate (PMMA), are transparent to light in the visible region, and are commonly used for the core of plastic optical fibers for communication using, for example, LEDs as a light source (wavelength 650 nm). However, PMMA has insufficient heat resistance (Tg: 105 ° C.), so its shape changes or the characteristics are impaired in applications and places where heat resistance is required, and the environment is substantially up to about 70 ° C. Can only be used in
[0004]
As an attempt to improve the heat resistance of PMMA, there are a method of copolymerizing α-methylstyrene and a method of copolymerizing maleic anhydride / styrene. In this case, although the heat resistance is improved, the mechanical strength is lowered accordingly, so that the fiber is easily broken when it is bent.
[0005]
Furthermore, in order to improve heat resistance, a method (Patent Document 1) of copolymerizing α-fluoroacrylic acid esters has been attempted. However, it is insufficient from the heat resistance requirement required for the heat-resistant optical material, particularly the plastic optical fiber for automobiles, which is the object of the present invention.
[0006]
In addition, methacrylic resins obtained by copolymerizing methyl methacrylate with cyclohexyl methacrylate or phenyl methacrylate have been synthesized (Patent Document 2 and Patent Document 3). These cyclohexyl methacrylate and phenyl methacrylate are used for the purpose of improving the hygroscopicity of PMMA. It has been introduced, and is insufficient from the heat resistance requirement required for the heat resistant optical material, particularly the plastic optical fiber for automobiles, which is the object of the present invention.
[0007]
On the other hand, polycarbonate resin is excellent in heat resistance (Tg: 145 ° C.). However, when it is used as a core material of an optical fiber, transmission loss of light is remarkably large, and transmission of a long-distance optical signal, for example, 20 m. There is a problem with transmissions that exceed.
[0008]
Amorphous polyolefin (Tg: 171 ° C., refractive index: 1.51) has particularly high heat resistance, but when exposed to the atmosphere at high temperatures, it tends to undergo coloring and gelation due to the influence of oxygen molecules. As a result, when used as a core material of an optical fiber, there is a problem that transmission loss of an optical signal is increased.
[0009]
2. Description of the Related Art In recent years, various sensors, signal processing devices, lighting, and the like aimed at upgrading, automation, and safety have been used for communication inside and outside an automobile. As a result, an increase in the amount of signal processing and an accompanying increase in the size of the electric wire cable occur, resulting in a problem of inhibiting the weight reduction of the vehicle body.
[0010]
In order to solve such a problem, it is desired to use an optical fiber capable of realizing multiplexing and high-speed communication instead of the electric cable.
[0011]
However, these LAN communication cables for vehicles (for in-vehicle LAN) are required to have heat resistance at high temperatures such as the engine room and the ceiling, and the distance from the vehicle design requirement is increased. However, a plastic optical fiber for automobiles having both heat resistance and signal transmission capability is required, but such an optical fiber has not been obtained for the aforementioned reasons.
[0012]
[Patent Document 1]
JP 63-33405 A
[Patent Document 2]
JP 59-1518
[Patent Document 3]
JP-A-61-36307
[0013]
[Problems to be solved by the invention]
An object of the present invention is to obtain an optical material having both heat resistance and signal transmission capability in view of the above prior art.
[0014]
Another object is to obtain an optical material having a signal transmission capability that can be used as a core material for optical transmission media, specifically plastic optical fibers and waveguide elements.
In particular, it is to obtain a plastic optical fiber using an optical material that can be used in an environment of 125 ° C. required in an engine room of an automobile or an environment of 150 ° C. required in an engine room of a diesel car.
[0015]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that a specific polymer having an alicyclic hydrocarbon moiety in the side chain is excellent in heat resistance, and further, alicyclic carbonization in the side chain. Among polymers having a hydrogen moiety, a polymer having a heat distortion temperature equal to or higher than a specific temperature is useful as a heat-resistant optical material. For example, it is useful as an optical material used for a plastic optical fiber for an in-vehicle LAN as described above. As a result, the present invention has been completed.
[0016]
That is, the heat-resistant optical material of the present invention is a heat-resistant optical material comprising a polymer having an alicyclic hydrocarbon moiety in the side chain, and thermal deformation of the polymer having an alicyclic hydrocarbon moiety in the side chain. The temperature is 115 ° C. or higher, and the formula (M-1):
-[M1]-[A]-(M-1)
[Where:
The structural unit M1 is represented by the formula (1):
[0017]
[Chemical 6]

[0018]
(Where X is H, CH_Three, F, Cl and CF_ThreeA structural unit derived from at least one monomer selected from the group consisting of: at least one selected from the group consisting of: Z is a monovalent organic group having 3 to 30 carbon atoms having an alicyclic hydrocarbon moiety;
The structural unit A is represented by a structural unit derived from at least one monomer copolymerizable with the monomer of formula (1)], the structural unit M1 is 1 to 100 mol%, and the structural unit A is 0 to 0. It consists of a polymer containing 99 mol%.
[0019]
The polymer of the formula (M-1) according to the present invention is a heavy polymer containing the structural unit (M1) derived from the acrylic monomer of the formula (1) having an alicyclic hydrocarbon moiety in the side chain as an essential component. It is a coalescence, and by introducing an alicyclic hydrocarbon into the side chain, it is transparent to light in the visible region and has a high glass transition temperature. Therefore, it is preferable as a heat-resistant optical material.
[0020]
Furthermore, the above-mentioned polymer has a heat distortion temperature of 115 ° C. or higher, and can be used as an optical material that can be used even in a high temperature environment of 70 ° C. or higher, for example, a plastic optical fiber for vehicle-mounted LAN.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The structural unit M1, which is an essential component in the polymer of the formula (M-1) of the present invention, has the general formula (M-2).
-[M1-1]-[M1-2]-(M-2)
[Where:
The structural unit M1-1 is represented by the formula (2):
[0022]
[Chemical 7]

[0023]
(Where Z¹Is a structural unit derived from at least one monomer represented by a C3-C30 monovalent organic group having an alicyclic hydrocarbon moiety),
The structural unit M1-2 is represented by the formula (3):
[0024]
[Chemical 8]

[0025]
(Where X^ThreeH, CH_Three, Cl and CF_ThreeAt least one selected from the group consisting of: Z²Is a structural unit derived from at least one monomer represented by a C3-C30 monovalent organic group having an alicyclic hydrocarbon moiety), and the structural unit M1-1 is represented by 1 to 99. It is preferably a structural unit containing 1 to 99 mol% of mol% and structural unit M1-2.
[0026]
A first preferred polymer of the present invention is that the M1-1 is 1 to 99 mol%, the structural unit M1-2 is 1 to 99 mol%, and the arbitrary structural unit A in the formula (M-1) is 0 to 98. It is a mol% polymer (M-2).
[0027]
That is, the structural unit M1-1 derived from α-fluoroacrylate having an aliphatic alicyclic hydrocarbon moiety in the side chain and monomers other than α-fluoroacrylate represented by formula (2) among the monomers of formula (1) A polymer having a monomer-derived structural unit M1-2 as an essential component. By introducing the structural unit M1-1, heat resistance and mechanical strength, particularly bending strength, and flexibility can be imparted.
[0028]
Further, by introducing the structural unit M1-2, heat resistance and transparency can be imparted, and furthermore, the refractive index can be adjusted (for example, set to PMMA or higher by increasing the refractive index).
[0029]
In the structural unit M1-2, X in the formula (2) is CH._ThreeIt is particularly preferable that it is a structural unit derived from methacrylate, and the same heat resistance and transparency as those described above and the function of adjusting the refractive index can be more effectively imparted.
[0030]
The abundance ratio of the structural units M1-1 and M1-2 may be one containing 1 to 99 mol% of M1-1 and 1 to 99 mol% of the structural unit M1-2, but M1-1 + M1-2 = 100. When M mol%, M1-1 / M1-2 is preferably 10/90 to 95/5 mol% ratio, more preferably 25/75 to 90/10 mol% ratio, particularly preferably 40/60 to 90 / The ratio is 10 mol%, more preferably 45/55 to 90/10 mol%.
[0031]
The structural unit A, which is an optional component in the polymer of the formula (M-1) or (M-2) of the present invention, is represented by the formula (M-3):
-[A-1]-[A-2]-(M-3)
[Where:
The structural unit A-1 is represented by the formula (4):
[0032]
[Chemical 9]

[0033]
(Where X¹Is H, CH_Three, F, Cl and CF_ThreeAt least one selected from the group consisting of: R¹Is a hydrogen atom, an alkyl group which may contain a linear or branched ether bond having 1 to 30 carbon atoms, and a fluorine-containing alkyl which may contain a linear or branched ether bond having 1 to 30 carbon atoms A structural unit and / or formula (5) derived from at least one monomer represented by at least one selected from the group consisting of groups:
[0034]
Embedded image

[0035]
(Where X²Is X in the formula (4)¹Same as R²Is a monovalent hydrocarbon group having 6 to 30 carbon atoms containing an aromatic ring, provided that R²A structural unit derived from at least one monomer represented by the following formula: (1), (4) And a structural unit derived from a monomer copolymerizable with the monomer shown in (5)], wherein 1 to 99 mol% of the structural unit A-1 and 0 to 0 of the structural unit A-2 are contained in the polymer. It is preferable that it is a structural unit containing -98 mol%.
[0036]
2nd of the preferable polymers of this invention are 1-99 mol% of structural units M1 which have an alicyclic hydrocarbon part in the side chain in the said formula (M-1), and do not contain the said alicyclic hydrocarbon part. It is a polymer (M-3) containing 1 to 99 mol% of the structural unit A-1 and further containing 0 to 98 mol% of the arbitrary structural unit A-2.
[0037]
By introducing a structural unit derived from the monomer of formula (4), mechanical properties and transparency can be imparted, and furthermore, the refractive index can be adjusted (for example, higher than the PMMA by increasing the refractive index). is there.
[0038]
By introducing a structural unit derived from the monomer of formula (5), further heat resistance, mechanical properties and low water absorption can be imparted, and further, the refractive index can be adjusted (for example, higher than that of PMMA by increasing the refractive index). Setting) is possible.
[0039]
X in structural unit A-1¹, X²Is CH_ThreeA methacrylate-derived structural unit is preferable in that heat resistance, transparency, and a refractive index adjusting function can be more effectively imparted.
[0040]
In structural unit A-1, X¹, X²Is a structural unit derived from α-fluoroacrylate which is an F atom, it is preferable in that heat resistance and mechanical strength, particularly bending strength, and flexibility can be imparted.
[0041]
That is, the structural unit A-1 is preferably a structural unit derived from at least one monomer selected from methyl methacrylate or methyl-α-fluoroacrylate, and can impart mechanical properties and transparency.
[0042]
Further, when the structural unit A-1 is a structural unit derived from at least one monomer selected from phenyl methacrylate and phenyl-α-fluoroacrylate, it is preferable in that it can impart further heat resistance and low water absorption.
[0043]
The abundance ratio of the structural units M1 and A-1 may be any as long as it contains 1 to 99 mol% of M1 and 1 to 99 mol% of the structural unit A-1, but when M1 + A-1 = 100 mol%, Preferably, M1 / A-1 is 5/95 to 90/10 mol% ratio, more preferably 5/95 to 60/40 mol% ratio, particularly preferably 10/90 to 50/50 mol% ratio, still more preferably The ratio is 10/90 to 40/60 mol%.
[0044]
In the formulas (M-1) and (M-3) of the present invention, X in the structural unit M1 derived from the monomer of the formula (1) is preferably an F atom, whereby heat resistance and mechanical properties are improved. Strength, particularly bending strength, and flexibility can be imparted.
[0045]
Z which forms a side chain in the polymer of formula (M-1) or (M-3) of the present invention, Z which forms a side chain in the polymer of formula (M-2)¹, Z²Is an organic group having 3 to 30 carbon atoms and having an alicyclic hydrocarbon moiety therein.
[0046]
The alicyclic hydrocarbon moiety may be a monocyclic hydrocarbon moiety, a polycyclic hydrocarbon moiety, or a hydrocarbon moiety including both.
[0047]
When the alicyclic hydrocarbon moiety includes a monocyclic hydrocarbon moiety, Z, Z¹, Z²Is preferably an organic group having 7 or more carbon atoms, whereby heat resistance can be imparted more effectively.
[0048]
In particular, Z, Z¹, Z²Is preferably an organic group containing a hydrocarbon moiety having a polycyclic structure, and can impart heat resistance and transparency more effectively.
[0049]
Z and Z in the case of containing a hydrocarbon moiety having a monocyclic structure¹, Z²Specifically,
(1) an organic group having a cyclopentyl group and a derivative thereof,
(2) an organic group having a cyclohexyl group and a derivative thereof,
(3) an organic group having a perhydrobiphenyl group and a derivative thereof,
(4) an organic group having spiro [4,4] nonane and derivatives thereof,
(5) Organic group having spiro [4,5] decane and its derivatives
Etc. are preferred, and some examples of them are as follows:
[0050]
Embedded image

[0051]
Etc.
[0052]
In addition, hydrogen atoms of these exemplified hydrocarbon groups may be substituted with an alkyl group having 1 to 5 carbon atoms, a fluorine atom, or a functional group.
[0053]
Z and Z in the case of containing a hydrocarbon moiety having a polycyclic structure¹, Z²Specifically,
(6) an organic group having adamantane and its derivatives,
(7) an organic group having norbornane and its derivatives,
(8) an organic group having perhydroanthracene and derivatives thereof,
(9) an organic group having perhydronaphthalene and derivatives thereof,
(10) Tricyclo [5.2.1.0^2,6 ] Organic group having decane and its derivatives
As examples of some of them,
[0054]
Embedded image

[0055]
Etc.
[0056]
In addition, hydrogen atoms of these exemplified hydrocarbon groups may be substituted with an alkyl group having 1 to 5 carbon atoms, a fluorine atom, or a functional group.
[0057]
Further, among these organic groups containing a hydrocarbon moiety of a polycyclic structure, adamantane and its derivatives, norbornane and its derivatives, tricyclo [5.2.1.0^{2, 6} Those containing decane and its derivatives are preferred, and these can particularly effectively impart heat resistance and transparency to the polymer.
[0058]
In the polymers of the formulas (M-1), (M-2), and (M-3) of the present invention, monomers (formulas (formulas) that can form a structural unit having an alicyclic hydrocarbon moiety in the side chain. 1), (2) and (3)) are specifically Z, Z¹, Z²An acrylic monomer having at least one side chain structure selected from, for example, the following can be exemplified.
[0059]
(I) A monomer having an organic group containing norbornane and derivatives thereof in the side chain
[0060]
Embedded image

[0061]
(Where X is H, F, Cl, CH_ThreeOr CF_ThreeR^1a, R^2a, R^3a, R^4a, R^5a, R^6a, R^7a, R^8a, R^9a, R^10aAre the same or different, and H, F, Cl, or an alkyl group which may be substituted with a halogen atom having 1 to 14 carbon atoms; R^11aIs a C 1-6 alkylene group which may contain a bond or a branched chain; n is an integer of 0, 1-2.
More specifically,
[0062]
Embedded image

[0063]
Etc.
[0064]
(II) Monomers having an organic group in the side chain containing adamantane and its derivatives
[0065]
Embedded image

[0066]
Or
[0067]
Embedded image

[0068]
(Where X is H, F, Cl, CH_Three, CF_ThreeR^1b, R^2bIs a substituent bonded to the ring, and CH_Three, C₂H_FiveOr OH; R^4b, R^5bIs an alkylene group having 1 to 6 carbon atoms which may have a bond or a branched chain; R^3bIs H, CH_ThreeOr C₂H_FiveN is 0 or an integer of 1 to 2), and more specifically,
[0069]
Embedded image

[0070]
Etc.
[0071]
(III) Tricyclo [5.2.1.0^2,6 Monomers having an organic group in the side chain containing decane and its derivatives
[0072]
Embedded image

[0073]
(Where X is H, F, Cl, CH_ThreeOr CF_ThreeR^1c, R^2c, R^3c, R^4c, R^5c, R^6c, R^7c, R^8c, R^9c, R^10c, R^11c, R^12c, R^13c, R^14c, R^15cAre the same or different, and an alkyl group having 1 to 14 carbon atoms which may be substituted with H, F, Cl or a halogen atom; R^16cIs an alkylene group having 1 to 6 carbon atoms which may contain a bond or a branched chain)
[0074]
Embedded image

[0075]
(Where X is H, F, Cl, CH_ThreeOr CF_ThreeR^1d, R^2d, R^3d, R^4d, R^5d, R^6d, R^7d, R^8d, R^9d, R^10d, R^11d, R^12d, R^13dAre the same or different, and an alkyl group having 1 to 14 carbon atoms which may be substituted with H, F, Cl or a halogen atom; R^14dIs an alkylene group having 1 to 6 carbon atoms which may contain a bond or a branched chain)
More specifically,
[0076]
Embedded image

[0077]
Etc.
[0078]
In the polymer of the formula (M-3) of the present invention, specific examples of the monomer that forms the structural unit A-1 include the following.
[0079]
As a specific example of the monomer having a chain hydrocarbon group of the formula (4) in the side chain,
[0080]
Embedded image

[0081]
(In the formula, n represents an integer of 1 to 6, m represents an integer of 0 to 29. Y represents H or F; R^1e, R^2e, R^3eAre the same or different and H is an alkyl group which may contain an ether bond having 1 to 29 carbon atoms or a fluorine-containing alkyl group which may contain an ether bond having 1 to 29 carbon atoms)
Etc.
[0082]
More specifically
[0083]
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[0084]
Among them, methacrylic acid, α-fluoroacrylic acid, acrylic acid, methyl methacrylate (MMA), and methyl-α-fluoroacrylate are preferable because they are excellent in improving transparency, heat resistance, and mechanical strength. In particular, MMA is excellent in improving optical characteristics and mechanical characteristics.
[0085]
As a specific example of the monomer having a hydrocarbon group containing an aromatic ring of the formula (5) in the side chain,
[0086]
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[0087]
(Where X²Are H, F, Cl, CH_Three, CF_ThreeR^1f, R^2f, R^3f, R^4f, R^5fAre the same or different, and an alkyl group having 1 to 14 carbon atoms which may be substituted with H, F, Cl or a halogen atom; R^6fIs an alkylene group having 1 to 6 carbon atoms which may have a bond or a branched chain), specifically,
[0088]
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[0089]
Are preferred.
[0090]
Of these, phenyl methacrylate and phenyl α-methacrylate are preferable in terms of improving heat resistance.
[0091]
The polymer used in the heat-resistant optical material of the present invention has a number average molecular weight in the range of 2,000 to 1,000,000, preferably 10,000 to 500,000, particularly preferably 50,000 to 300,000. A molecular weight that is too low is not preferred in that mechanical properties, particularly bending strength, and flexibility are lowered. On the other hand, a molecular weight that is too high is not preferable in that the moldability is lowered or the transparency is lowered due to an increase in light scattering.
[0092]
The polymer used in the heat-resistant optical material of the present invention has a heat distortion temperature of 115 ° C. or higher, thereby suppressing softening even in a high-temperature environment, and as a result, scattering of the optical signal can be reduced and good optical signal transmission can be achieved. (Transmission with less loss of optical signals over long distances) becomes possible.
[0093]
The heat distortion temperature in the present invention means a deflection temperature under load (HDT), and uses a value measured by a method standardized by ASTM D684.
In particular, the heat distortion temperature is preferably 120 ° C. or higher, particularly 130 ° C. or higher, and more preferably 140 ° C. or higher. It is advantageous for optical parts, optical communication media, plastic optical fibers, etc. used in high-temperature environments such as for controlling industrial robots.
[0094]
The heat-resistant optical material of the present invention needs to have high transparency with respect to light in the visible region, and is particularly preferable to have high transparency with respect to light having a wavelength of 650 nm.
[0095]
From this point of view, the heat-resistant optical material of the present invention has an extinction coefficient of 0.015 cm at 650 nm wavelength light.^-1Or less, particularly 0.014 cm^-1Below, further 0.013 cm^-1The following is preferable. Thereby, the absorption loss of the optical signal can be reduced, and the loss can be reduced even in the transmission of the optical signal over a long distance of 20 to 100 m.
[0096]
Here, the extinction coefficient is a plastic optical fiber having a length of 100 mm using the heat-resistant optical material of the present invention as a core material by melt spinning with a clad material having an appropriate refractive index. Measure the transmitted light intensity. Incident light intensity I₀, Transmitted light intensity I₁, The extinction coefficient is a value calculated by the following equation.
Absorption coefficient = 1/10 · log (I₀/ I₁)
[0097]
The heat-resistant optical material of the present invention can adjust the refractive index in a wide range. Thereby, it can be used for an optical transmission medium or a clad.
[0098]
In particular, since the heat-resistant optical material of the present invention is highly transparent and can be adjusted to a high refractive index, it can be used for an optical transmission medium, for example, a core of a plastic optical fiber or an optical waveguide device.
[0099]
In that case, the heat-resistant optical material of the present invention has a refractive index of n_DIt is preferable that it is 1.45 or more.
[0100]
The refractive index is a value measured with an Abbe refractometer at 25 ° C. using sodium D line as a light source.
[0101]
The refractive index is preferably 1.47 or more, more preferably 1.48 or more, and the most preferable range is 1.48 to 1.52. If the refractive index is too low, it is not preferable in that the selection of the material on the clad material side is restricted when producing a plastic optical fiber. If the refractive index is too high, transmission loss due to light scattering increases, and coupling loss increases when a plastic optical fiber is joined.
[0102]
The description has been given above from the viewpoint of the structural unit and physical properties (characteristics). Next, preferred specific examples of the polymer used in the heat-resistant optical material of the present invention will be described.
[0103]
Polymer (I)
Formula (M-4):
-[M1-1a]-[A-1a]-(M-4)
[Wherein, the structural unit M1-1a is represented by the formula (2-1):
[0104]
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[0105]
(Where Z^ThreeIs adamantane and its derivatives, norbornane and its derivatives, tricyclo [5.2.1.0^2,6 A monovalent organic group having 10 to 30 carbon atoms containing a hydrocarbon moiety of at least one polycyclic structure selected from decane and its derivatives); the structural unit A-1a is a structural unit derived from methyl methacrylate] A polymer containing 1 to 100 mol% of the structural unit M1-1a and 0 to 99 mol% of the structural unit A-1a.
[0106]
This polymer is preferable in terms of high transparency and mechanical strength, in particular, excellent bending strength and flexibility.
[0107]
Polymer (II)
Formula (M-5):
-[M1-1a]-[A-1a]-[A-2a]-(M-5)
(Wherein the structural units M1-1a and A-1a are the same as those in the formula (M-4); the structural unit A-2a is a structural unit derived from phenyl methacrylate or phenyl-α-fluoroacrylate) and has the structure A polymer containing 1 to 99 mol% of the unit M1-1a, 0 to 98 mol% of the structural unit A-1a, and 1 to 99 mol% of the structural unit A-2a.
[0108]
This polymer is preferable in that it has excellent heat resistance and low water absorption.
[0109]
Polymer (III)
Formula (M-6):
-[M1-1a]-[M1-2a]-[A-1a]-(M-6)
[In the formula, the structural units M1-1a and A-1a are the same as the formula (M-4); the structural unit M1-2a is the formula (3-1):
[0110]
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[0111]
(Where Z^FourIs adamantane and its derivatives, norbornane and its derivatives, tricyclo [5.2.1.0^2,6 ] A monovalent organic group having 10 to 30 carbon atoms and containing a hydrocarbon moiety of at least one polycyclic structure selected from decane and derivatives thereof]
A polymer containing 1 to 99 mol% of the structural unit M1-1a, 1 to 99 mol% of the structural unit M1-2a, and 0 to 98 mol% of the structural unit A-1a.
[0112]
This polymer is preferable in that it has excellent heat resistance and mechanical strength, particularly bending strength, and can easily adjust the refractive index.
[0113]
When the heat-resistant optical material of the present invention is used particularly for the core, additives may be mixed within a range not impairing the heat resistance and signal transmission performance.
[0114]
For example, in order to adjust the refractive index, benzyl phthalate-n-butyl (refractive index: 1.575), 1-methoxyphenyl-1-phenylethane (refractive index: 1.571), benzyl benzoate (refractive index) : 1.568), bromobenzene (refractive index: 1.557), o-dichlorobenzene (refractive index: 1.551), m-dichlorobenzene (refractive index: 1.543), 1,2'-dibromoethane. (Refractive index: 1.538), 3-phenyl-1-propanol (refractive index: 1.532), diphenylphthalic acid (C₆H_Four(COOC₆H_Five)₂), Triphenylphosphine ((C₆H_Five)_ThreeP) and dibenzyl phosphate ((C₆H_FiveCH₂O)₂PHO₂), 4,4′-dibromobenzyl, 4,4′-dibromobiphenyl, 2,4′-dibromoacetophenone, 3 ′, 4′-dichloroacetophenone, 3,4-dichloroaniline, 2,4-dibromoaniline, 2 , 6-Dibromoaniline 1,4-dibromobenzene and the like can be added. These low molecular weight compounds not only simply adjust the refractive index of the heat-resistant optical material of the present invention, but also provide, for example, a refractive index distribution (graded index) type optical fiber described in JP-A-8-110420. Function as a dopant. The heat-resistant optical material of the present invention is also a useful material for obtaining a heat-resistant refractive index distribution (graded index) type optical fiber.
[0115]
The heat-resistant optical material of the present invention is preferably used for an optical transmission medium and a core material of a plastic optical fiber formed by a core and a clad.
[0116]
Since the plastic optical fiber using the heat-resistant optical material of the present invention has high heat resistance, it is useful when heat resistance of 100 ° C. or higher is required. For example, in a light guide, heat resistance is required when laying a plastic optical fiber close to a halogen light source. In sensor applications, heat resistance is required when detecting a part where the atmosphere is hot, such as detection of headlight illumination of a car or positioning sensor of a melt press. The same applies to sensors for industrial robots. In optical communication applications, heat resistance of 100 ° C. or higher is required when wiring in an engine room, a car ceiling, an installed panel, or the like that becomes high temperature in an in-vehicle LAN. The same applies when mounted on an aircraft. For plastic optical fiber wiring in factory automation (FA) applications, heat resistance is required when exposed to high temperature environments. Further, even when used outdoors or indoors, heat resistance is required for an environment where there is no normal air conditioning equipment such as a switchboard room on a building roof or a communication base station. The heat-resistant optical material of the present invention can be effectively used for these applications.
[0117]
These optical materials used for the clad of the plastic optical fiber using the heat-resistant optical material have a glass transition temperature of 100 ° C. or higher and a refractive index (n_D) Is preferably 1.44 or less.
[0118]
The optical material used for the clad preferably has a glass transition temperature of 105 ° C. or higher, more preferably 110 ° C. or higher, still more preferably 120 ° C., particularly 130 ° C. or higher. Heat resistance can be improved by a high glass transition temperature, and it is preferable in that it can constitute a high heat-resistant plastic optical fiber in combination with the heat-resistant optical material of the present invention used for the core. Can be used more effectively.
[0119]
The polymer used as the heat-resistant clad is preferably a fluorine-containing acrylic resin having a refractive index of 1.44 or less, and a (co) copolymer of a methacrylate having a fluoroacryl group in the side chain and α-fluoroacrylate. Coalescence is preferred. Among these, as a fluorine-containing acrylate having both heat resistance (high glass transition temperature) and a low refractive index, the formula (6):
[0120]
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[0121]
(Where X^ThreeIs H, CH_Three, F, CF_ThreeOr Cl; Rf¹And Rf²Are the same or different, and a polymer having a structural unit (a) represented by a perfluoroalkyl group having 1 to 5 carbon atoms; W is a hydrocarbon group having 1 to 5 carbon atoms which may be substituted with a fluorine atom) Is preferred.
[0122]
In particular, a fluorine-containing copolymer comprising a structural unit of the above formula (6) and a structural unit derived from methyl methacrylate is preferable. For example, the structural unit (a) of the above formula (6) and the structural unit (b) derived from methyl methacrylate are preferred. A fluorine-containing copolymer having a ratio of (a) / (b) of 32/68 to 64/36 mol% when the total is 100 is preferable.
[0123]
The layer structure of the plastic optical fiber is usually composed of a core layer and a clad layer from the inside. Although there is no restriction | limiting in particular in a diameter, Usually, it is about 125 micrometers-1 mm. The thickness of each layer is normally about core layer / cladding layer = 98/2, and the core layer occupies most of it. Further, a protective layer may be provided on the outer periphery. This protective layer is mainly used for the purpose of improving heat resistance, reducing bending loss, and improving impact resistance. Usually, a vinylidene fluoride copolymer is used. Of these, vinylidene fluoride / tetrafluoroethylene copolymer is preferred. The thickness of the protective layer is almost the same as that of the cladding layer. Moreover, when using as an optical fiber cable, a coating layer is further arrange | positioned on the outer periphery. As the covering layer, conventionally used nylon 12, polyvinyl chloride, polyethylene, polyurethane, polypropylene and the like can be used.
[0124]
In the above configuration, the core layer having a single refractive index is called an SI (step index) type plastic optical fiber, and is the most common.
[0125]
The one in which the refractive index of the core layer decreases stepwise from the inner periphery to the outer periphery is called a multi-step type plastic optical fiber. Also, the one in which the refractive index smoothly decreases from the inner periphery toward the outer periphery is called a GI (graded index) type plastic optical fiber.
[0126]
As a method for producing the plastic optical fiber, for example, in the case of an SI type plastic optical fiber, the core material polymer and the clad material polymer are arranged concentrically using a composite spinning nozzle, and are shaped into a fiber shape by melt compound spinning. Then, a method of performing a stretching process under heating for the purpose of improving mechanical strength is common.
[0127]
The heat-resistant optical material of the present invention can be preferably used as a core of an optical waveguide device, and specific examples of the same polymer as the core material and the clad material can also be preferably exemplified.
[0128]
FIG. 1 illustrates a main structure of a typical optical waveguide element. Here, 1 is a substrate, 2 is a core portion, and 3 and 4 are cladding portions. Such an optical waveguide element is used to connect optical functional elements, and light transmitted from the terminal of one optical functional element passes through the core portion 2 of the optical waveguide element, for example, the core portion 2 and the cladding portion 3. 4 is propagated to the other optical functional device terminal while repeating total reflection at the interface with. The optical waveguide element can take an appropriate form such as a planar type, a strip type, a ridge type, and an embedded type.
[0129]
For example, optical waveguide elements include elements that exhibit switching, amplification, wavelength conversion, optical multiplexing / demultiplexing, wavelength selection, and the like for optical communication signals, and can be used for optical switches, optical routers, ONUs, media converters, and the like.
[0130]
The heat-resistant optical material of the present invention is used for other applications than the above, for example, lenses (pickup lenses, lenses for glasses, lenses for cameras, Fresnel lenses for projectors, contact lenses), sealing materials for light emitters such as LEDs, reflection Examples thereof include a preventive material, an optical disk substrate, a cover material for a lighting fixture, a display protective plate, a transparent case, a display plate, and automotive parts.
[0131]
【Example】
Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.
[0132]
Example 1
30 g of 2-methyl-2adamantyl α-fluoroacrylate, 70 g of methyl methacrylate (MMA), 0.1 g of n-lauryl mercaptan and 0.025 g of azoisobutyronitrile were dissolved and mixed in a 500 ml glass flask, deaerated and After nitrogen substitution was repeated and sealed, polymerization was performed at 70 ° C. for 16 hours.
[0133]
After completion of the polymerization, 300 g of acetone was added to the product to dissolve it, and the resulting solution was poured into 5 liters of methanol. The precipitated polymer was separated from the liquid and dried under reduced pressure at a temperature of 100 ° C. for 10 hours to obtain 92 g (yield 92%) of a solid polymer.
[0134]
The resulting polymer¹⁹FNMR,¹It was measured by HNMR and IR method, and confirmed to be a copolymer of 2-methyl-2adamantyl α-fluoroacrylate / MMA = 15/85 (mol%).
[0135]
Further, the weight average molecular weight, refractive index, glass transition temperature, heat distortion temperature, melt index, extinction coefficient and tensile strength of the obtained copolymer were examined. The results are shown in Table 1.
[0136]
The physical property value is measured by the following method.
(1) Weight average molecular weight (Mw)
Measured by GPC method (polystyrene conversion).
[0137]
(2) Refractive index (n_D)
Measurement is performed using an Abbe refractometer manufactured by Atago Optical Instruments Co., Ltd. at 25 ° C. using sodium D line as a light source.
[0138]
(3) Glass transition temperature (Tg)
Using a DSC (differential scanning calorimeter) manufactured by Seiko Electronics Co., Ltd., 1st run was increased to 200 ° C. at a temperature increase rate of 10 ° C./min, maintained at 200 ° C. for 1 minute, and then at a temperature decrease rate of 10 ° C./min. After cooling to 25 ° C., the intermediate point of the endothermic curve of 2nd run obtained at a heating rate of 10 ° C./min is defined as Tg.
[0139]
(4) Thermal deformation temperature (HDT)
Using an HDT test device manufactured by Toyo Seiki Seisakusho Co., Ltd., measurement is performed according to ASTM D684.
[0140]
(5) Melt index (MI)
Using a descending flow tester manufactured by Shimadzu Corporation, each copolymer was attached to a cylinder with an inner diameter of 9.5 mm and maintained at a temperature of 230 ° C. for 5 minutes, and then a 7 kg piston load part with an inner diameter of 2.1 mm, Expressed in grams of copolymer extruded through an orifice 8 mm long and extruded in 10 minutes.
[0141]
(6) Absorption coefficient (ε)
Copolymer comprising a polymer as a core material, 50% by weight of 2,2,2-trifluoroethyl methacrylate, 30% by weight of 2,2,3,3-tetrafluoropropyl methacrylate as a cladding material, and 20% by weight of methyl methacrylate. The composite optical fiber is spun at 230 ° C. to produce a plastic optical fiber having a diameter of 300 μm (cladding material thickness: 15 μm) and a length of 100 mm. The transmittance of the optical fiber is measured with light at a wavelength of 650 nm. Incident light intensity I₀, Transmitted light intensity I₁, The extinction coefficient, ε is calculated by the following equation.
ε = 1/10 · log (I₀/ I₁)
[0142]
(7) Tensile strength (F)
The tensile strength is measured according to ASTM D638 using a universal testing machine manufactured by Shimadzu Corporation.
[0143]
Example 2
A copolymer was obtained in the same manner as in Example 1 except that 15 g of isobornyl α-fluoroacrylate, 15 g of phenyl α-fluoroacrylate, and 70 g of MMA were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0144]
Example 3
A copolymer was obtained in the same manner as in Example 1 except that 40 g of tricyclodecanyl α-fluoroacrylate and 60 g of methyl α-fluoroacrylate were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0145]
Example 4
A copolymer was obtained in the same manner as in Example 1 except that 25 g of 2-methyl-2adamantyl α-fluoroacrylate, 25 g of isobornyl methacrylate and 50 g of MMA were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0146]
Example 5
A copolymer was obtained in the same manner as in Example 1 except that 15 g of cyclohexyl α-fluoroacrylate, 25 g of phenyl α-fluoroacrylate and 60 g of methyl α-fluoroacrylate were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0147]
Comparative Example 1
A MMA homopolymer was obtained in the same manner as in Example 1 except that only 100 g of MMA was used as the monomer. Various physical properties of the obtained polymer were measured in the same manner as in Example 1. The results are shown in Table 1.
[0148]
Comparative Example 2
A copolymer was obtained in the same manner as in Example 1 except that 30 g of phenyl methacrylate and 70 g of MMA were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0149]
Comparative Example 3
A copolymer was obtained in the same manner as in Example 1 except that 25 g of 2,2,2-trifluoroethyl α-fluoroacrylate and 75 g of MMA were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0150]
Comparative Example 4
A copolymer was obtained in the same manner as in Example 1 except that 50 g of 2,2,3,3,3-pentafluoropropyl α-fluoroacrylate and 50 g of phenyl methacrylate were used as monomers. The composition of the obtained copolymer and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.
[0151]
[Table 1]

[0152]
Synthesis example 1
A polymer was obtained in the same manner as in Example 1, except that 50 g of 2,2-bis (trifluoromethyl) propanyl methacrylate, 20 g of MMA, and 30 g of 1H, 1H, 3H-tetrafluoropropyl methacrylate were used as monomers. . The polymer obtained had a glass transition temperature of 110 ° C., an MI of 37 g / 10 min, and a refractive index of 1.419.
[0153]
Example 6
As a core material, the polymer of Example 1 was used as a clad material, and consisted of 50% by weight of 2,2,2-trifluoroethyl methacrylate, 30% by weight of 2,2,3,3-tetrafluoropropyl methacrylate and 20% by weight of methyl methacrylate Using the copolymer, composite spinning was performed at 230 ° C. to produce a plastic optical fiber having a diameter of 300 μm (sheath material thickness: 15 μm) and a length of 50 m. With respect to the transmission loss of this plastic optical fiber, the transmission loss at a wavelength of 650 nm at an incident NA = 0.1 was measured by a cut-back method of 25 m-5 m. Further, this plastic optical fiber was kept at 100 ° C. for 168 hours, and the transmission loss at a wavelength of 650 nm thereafter was similarly measured. The results are shown in Table 2.
[0154]
Example 7
A plastic optical fiber was obtained in the same manner as in Example 6 except that the polymer of Example 4 was used as the core material and the polymer of Synthesis Example 1 was used as the cladding material. Table 2 shows the characteristics of the obtained plastic optical fiber.
[0155]
Comparative Example 5
A plastic optical fiber was obtained in the same manner as in Example 6 except that the polymer of Comparative Example 3 was used as the core material. Table 2 shows the characteristics of the obtained plastic optical fiber.
[0156]
[Table 2]

[0157]
【The invention's effect】
According to the present invention, an optical material having both heat resistance and signal transmission capability can be provided.
[0158]
Furthermore, optical transmission media, in particular, optical materials with signal transmission capability that can be used as core materials for plastic optical fibers and waveguide elements, particularly in the 125 ° C environment required in the engine room of automobiles, or in diesel vehicles. A plastic optical fiber using an optical material that can be used in an environment of 150 ° C. required in an engine room can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a main structure of an optical waveguide element.
[Explanation of symbols]
1 Substrate
2 Core part
3 Clad part
4 Clad part

Claims (23)

A heat-resistant optical material comprising a polymer having an alicyclic hydrocarbon moiety in the side chain, wherein the polymer having the alicyclic hydrocarbon moiety in the side chain has a thermal deformation temperature of 115 ° C. or higher, and Formula (M-1):
-[M1]-[A]-(M-1)
[Where:
The structural unit M1 is represented by the formula (1):

(Wherein X is at least one selected from the group consisting of H, CH ₃ , F, Cl and CF ₃ ; Z is a C 3-30 monovalent organic group having an alicyclic hydrocarbon moiety) Structural units derived from at least one of the monomers shown,
The structural unit A is represented by a structural unit derived from at least one monomer copolymerizable with the monomer of formula (1)], the structural unit M1 is 1 to 100 mol%, and the structural unit A is 0 to 0. A heat-resistant optical material which is a polymer containing 99 mol%. The structural unit M1 of the polymer having an alicyclic hydrocarbon moiety in the side chain is represented by the formula (M-2):
-[M1-1]-[M1-2]-(M-2)
[Where:
The structural unit M1-1 is represented by the formula (2):

(Wherein, Z ¹ is a structural unit derived from at least one of the monomers represented by (C 1-30 monovalent organic group having an alicyclic hydrocarbon moiety);
The structural unit M1-2 is represented by the formula (3):

(Wherein X ³ is at least one selected from the group consisting of H, CH ₃ , Cl and CF ₃ ; Z ² is a monovalent organic group having 3 to 30 carbon atoms and having an alicyclic hydrocarbon moiety) A structural unit derived from at least one of the monomers represented by formula (1) to (1) to 99 mol% of the structural unit M1-1 and 1 to 99 mol% of the structural unit M1-2. 1. The heat-resistant optical material according to 1. The structural unit A of the polymer having an alicyclic hydrocarbon moiety in the side chain is represented by the formula (M-3):
-[A-1]-[A-2]-(M-3)
[Where:
The structural unit A-1 is represented by the formula (4):

(Wherein X ¹ is at least one selected from the group consisting of H, CH ₃ , F, Cl and CF ₃ ; R ¹ includes a hydrogen atom and a linear or branched ether bond having 1 to 30 carbon atoms. At least one selected from the group consisting of an alkyl group which may be a fluorine atom and a fluorine-containing alkyl group which may contain a linear or branched ether bond having 1 to 30 carbon atoms. Structural units derived from species and / or formula (5):

(Wherein X ² is the same as X ^{1 in the} formula (4); R ² is a monovalent hydrocarbon group having 6 to 30 carbon atoms including an aromatic ring, provided that one of the hydrogen atoms in R ^{2 is} A structural unit derived from at least one of the monomers represented by the formula (1), (4) and (5) A structural unit derived from a monomer copolymerizable with the monomer] and comprising 1 to 99 mol% of structural unit A-1 and 0 to 98 mol% of structural unit A-2 in the polymer The heat-resistant optical material according to claim 1 or 2, which is a unit.   The heat-resistant optical material according to claim 3, wherein the structural unit A-1 is a structural unit derived from at least one monomer represented by formula (4).   The heat-resistant optical material according to claim 4, wherein the structural unit A-1 is a structural unit derived from methyl methacrylate or methyl-α-fluoroacrylate.   The heat-resistant optical material according to claim 3, wherein the structural unit A-1 is a structural unit derived from at least one monomer represented by the formula (5).   The heat-resistant optical material according to claim 6, wherein the structural unit A-1 is a structural unit derived from phenyl methacrylate or phenyl-α-fluoroacrylate.   X in said Formula (1) is F, The heat resistant optical material in any one of Claim 1 or 3-7.   The heat-resistant optical material according to any one of claims 1 to 8, wherein Z in the formula (1) is a monovalent organic group having 4 to 30 carbon atoms having a hydrocarbon moiety having a polycyclic structure. Any of claims 2-8, at least one of Z ² in Z ¹ and Equation (3) is a monovalent organic group having 4 to 30 carbon atoms having a hydrocarbon portion having polycyclic structure of formula (2) The heat-resistant optical material described.   The heat-resistant optical material according to claim 9 or 10, wherein the monovalent organic group having a hydrocarbon moiety having a polycyclic structure is an organic group having 10 to 30 carbon atoms including adamantane or a derivative thereof.   The heat-resistant optical material according to claim 9 or 10, wherein the monovalent organic group having a hydrocarbon moiety having a polycyclic structure is an organic group having 7 to 30 carbon atoms including norbornane or a derivative thereof. The monovalent organic group having a hydrocarbon moiety having a polycyclic structure is an organic group having 10 to 30 carbon atoms including tricyclo [5.2.1.0 ^2,6 ] decane or a derivative thereof. The heat-resistant optical material described.   The heat-resistant optical material according to any one of claims 1 to 13, wherein the polymer having an alicyclic hydrocarbon moiety in the side chain is a polymer having a heat distortion temperature of 130 ° C or higher. The heat-resistant optical material according to any one of claims 1 to 14, wherein the polymer having an alicyclic hydrocarbon moiety in the side chain is a polymer having an extinction coefficient at 650 nm wavelength light of 0.015 cm ^-1 or less. . The heat-resistant optical material according to any one of claims 1 to 15, wherein the polymer having an alicyclic hydrocarbon moiety in the side chain is a polymer having a refractive index n _D of 1.45 or more. The heat-resistant optical material according to claim 1, wherein the polymer having an alicyclic hydrocarbon moiety in the side chain is a polymer having a refractive index n _D of 1.47 or more.   An optical transmission medium using the heat-resistant optical material according to claim 1.   A plastic optical fiber composed of a core and a clad, wherein the optical optical medium uses the optical transmission medium according to claim 18. The plastic optical fiber according to claim 19, wherein the clad is a material having a glass transition temperature of 100 ° C or higher and a refractive index n _D of 1.44 or lower.   The plastic optical fiber according to claim 20, wherein the clad is a material having a glass transition temperature of 105 ° C or higher.   The plastic optical fiber according to any one of claims 19 to 21, which is a plastic optical fiber for LAN mounted on a vehicle.   19. An optical waveguide element comprising a core and a clad, wherein the optical waveguide medium uses the optical transmission medium according to claim 18.

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