JP3944714B2 - Plastic optical fiber and manufacturing method thereof - Google Patents

Description

〔式中、Ｒ ¹ は炭素原子数１〜９の同一又は異種の非置換又は置換の一価炭化水素基を表し、Ｘは下記一般構造式（２）：
【化２５】

（式中、Ｒ ² は炭素原子数２〜４の二価炭化水素基又は酸素原子であり、Ｒ ³ は１〜３個の（メタ）アクリロイル基を有する炭素原子数４〜２５の一価有機基であり、Ｒ ⁴ は同一又は異種の炭素原子数１〜９の非置換又は置換の一価炭化水素基であり、Ｒ ⁵ は同一又は異種の炭素原子数１〜１８の一価炭化水素基である。また、ｎは１〜３、ｍは０〜２で、かつ１≦ｎ＋ｍ≦３を満足する整数であるが、ｎが１のときＲ ³ は２又は３個の（メタ）アクリロイル基を有する。）
で表される基であり、Ｌは８〜１０，０００の整数である。〕
で示される分子鎖両末端にそれぞれ少なくとも２個の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサン、及び下記一般構造式（３）：
【化２６】

〔式中、Ｒ ¹ は前述したものと同様であり、Ｒ ⁶ は同一又は異種の下記一般構造式（４）：
【化２７】

（式中、Ｒ ⁸ は二価炭化水素基であり、Ｒ ⁹ は水素原子又はメチル基である。）
で表される基又はメチル基であり、Ｒ ⁷ は同一又は異種の上記一般構造式（４）で表される基であって、ｓ及びｔはｓ＋ｔ≧１０及び０．０５≦ｓ／（ｓ＋ｔ）≦０．５を満たす正の整数である。〕
で表される、分子側鎖に複数の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサンから選択される１種又は２種以上の、（メタ）アクリロイル基含有オルガノポリシロキサンをベースポリマーとして含み、更に増感剤及び／又は光重合開始剤を含む紫外線硬化型樹脂組成物の紫外線硬化物を用いたことを特徴とするプラスチック光ファイバ、及び、熱可塑性又は熱硬化性樹脂製の管状クラッドの内部に、該クラッドより高い屈折率を有する硬化物を与える、上記一般構造式（１）で示される分子鎖両末端にそれぞれ少 なくとも２個の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサン、及び上記一般構造式（３）で表される、分子側鎖に複数の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサンから選択される１種又は２種以上の、（メタ）アクリロイル基含有オルガノポリシロキサンをベースポリマーとして含み、更に増感剤及び／又は光重合開始剤を含む紫外線硬化型樹脂組成物を充容した後、上記クラッドの外部からクラッドを通して上記組成物に紫外線を照射して該組成物を硬化させることにより、上記クラッドと一体にコアを製造することを特徴とするプラスチック光ファイバの製造方法を提供する。
【００１１】
以下、本発明につき更に詳しく説明する。
本発明の光ファイバは、透明コアと、このコアを被覆する透明管状クラッドとを備えたもので、上記コアは、上記管状クラッドよりも屈折率が大きいものである。
【００１２】
この場合、上記コアは紫外線硬化型樹脂組成物の硬化物から構成されるもので、この紫外線硬化型樹脂組成物は、紫外線硬化反応する透明な樹脂を主成分とし、増感剤及び／又は光重合開始剤を含有するものである。
【００１３】
ここで、上記コアとなる樹脂は、紫外線で硬化反応する透明な樹脂であれば特に制限されるものではないが、増感剤を含有したアクリル官能基を有するオルガノポリシロキサン（シリコーン）樹脂やウレタン樹脂、光カチオン重合開始剤を含有するオルガノポリシロキサン（シリコーン）樹脂やウレタン樹脂等が挙げられる。特にオルガノポリシロキサン（シリコーン）樹脂は、耐熱性や耐候性に優れるため好ましく、紫外線硬化型樹脂組成物としては、紫外線硬化可能なオルガノポリシロキサン組成物が好ましい。
【００１４】
紫外線硬化可能なオルガノポリシロキサン（シリコーン）樹脂組成物としては、特公平４−２５２３１号、特公平６−８３３５号、特公平６−１７４３５号、特公平６−２７１６２号などに挙げられるアクリル官能基を有するシリコーン樹脂組成物や、特許１５３０５８０号、特許２７３１９３２号、特許２５１６８９７号などで提案されているメルカプト基を有するシリコーン樹脂組成物などが挙げられる。なかでも、アクリル官能基を有するシリコーン樹脂組成物は、メルカプト基を有するシリコーン樹脂組成物のような異臭も無く、好適に使用することができる。これらのアクリル官能基を有するオルガノポリシロキサン（シリコーン）樹脂組成物を構成する主剤（ベースポリマー）としてのアクリル官能性基含有オルガノポリシロキサンとしては、例えば、下記一般構造式（１）：
【化１】

〔式中、Ｒ¹は炭素原子数１〜９の同一又は異種の非置換又は置換の一価炭化水素基を表し、Ｘは下記一般構造式（２）：
【化２】

（式中、Ｒ²は炭素原子数２〜４の二価炭化水素基又は酸素原子であり、Ｒ³は１〜３個の（メタ）アクリロイル基を有する炭素原子数４〜２５の一価有機基であり、Ｒ⁴は同一又は異種の炭素原子数１〜９の非置換又は置換の一価炭化水素基であり、Ｒ⁵は同一又は異種の炭素原子数１〜１８の一価炭化水素基である。また、ｎは１〜３、ｍは０〜２で、かつ１≦ｎ＋ｍ≦３を満足する整数である。）で表される基であり、Ｌは８〜１０，０００の整数である。〕
で示される分子鎖両末端に少なくとも１個の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサン、及び下記一般構造式（３）：
【化３】

〔式中、Ｒ¹は前述したものと同様であり、Ｒ⁶は同一又は異種の下記一般構造式（４）：
【化４】

（式中、Ｒ⁸は二価炭化水素基であり、Ｒ⁹は水素原子又はメチル基である。）
で表される基又はメチル基であり、Ｒ⁷は同一又は異種の上記一般構造式（４）で表される基であって、ｓ及びｔはｓ＋ｔ≧１０及び０．０５≦ｓ／（ｓ＋ｔ）≦０．５を満たす正の整数である。〕
で表される、分子側鎖に複数の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサンを例示することができる。
【００１５】
ここで、上記オルガノポリシロキサンはベースポリマーとして使用される成分であって、一般構造式（１）及び／又は（３）で示される１種又は２種以上のものを好適に使用することができる。
【００１６】
上記一般構造式（１）で示される分子鎖両末端に少なくとも１個の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサンにおいて、Ｒ¹は同一又は異種の炭素原子数１〜９、好ましくは１〜６の非置換又は置換の一価炭化水素基である。このＲ¹の一価炭化水素基の具体例としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、ヘキシル基、ヘプチル基、２−エチルヘキシル基、オクチル基、ノニル基等のアルキル基；シクロヘキシル基、シクロヘプチル基等のシクロアルキル基；ビニル基、アリル基、プロペニル基、イソプロペニル基、ブテニル基、ヘキセニル基等のアルケニル基；フェニル基、トリル基等のアリール基；ベンジル基、フェニルエチル基、フェニルプロピル基等のアラルキル基；又はこれらの基の炭素原子に結合した水素原子の少なくとも一部をハロゲン原子、シアノ基等の置換基で置換した、クロロメチル基、シアノエチル基、トリフルオロプロピル基などが挙げられるが、Ｒ¹の５０モル％以上（５０〜１００モル％、特に７５〜９７モル％）がメチル基で、かつ２５モル％以下（０〜２５モル％、特に３〜２０モル％）がフェニル基であるものが好ましい。
【００１７】
上記一般構造式（１）において、Ｘは一般構造式（２）で表される基である。一般構造式（２）におけるＲ²は炭素原子数２〜４の二価炭化水素基又は酸素原子であるが、耐水性の点から好ましくは二価炭化水素基である。このＲ²の二価炭化水素基の具体例としては、エチレン基、プロピレン基、メチルエチレン基、テトラメチレン基等の炭素原子数２〜４のアルキレン基が挙げられるが、好ましくはエチレン基である。
【００１８】
上記一般構造式（２）におけるＲ³は（メタ）アクリロイル基（特に（メタ）アクリロイロキシ基）を１〜３個、好ましくは２〜３個、更に好ましくは３個有する、炭素原子数４〜２５の一価有機基である。Ｒ³における（メタ）アクリロイル基の具体例としては、ＣＨ₂＝ＣＨＣＯＯ−、ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯ−、ＣＨ₂＝ＣＨＣＯ−、ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯ−等のアクリル官能性基、メタクリル官能性基などが挙げられる。
【００１９】
このような（メタ）アクリロイル基を含むＲ³の一価有機基の具体例としては、ＣＨ₂＝ＣＨＣＯＯＣＨ₂ＣＨ₂−、（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂）₃Ｃ−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）₃Ｃ−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）₂Ｃ（Ｃ₂Ｈ₅）ＣＨ₂−、ＣＨ₂＝ＣＨＣＯＯＣＨ₂ＣＨ（ＣＨ₂ＯＣ₆Ｈ₅）−、ＣＨ₂＝ＣＨＣＯＯＣＨ₂−Ｓｉ（ＣＨ₃）₂−、ＣＨ₂＝ＣＨＣＯＯＣＨ₂ＣＨ₂ＣＨ₂−Ｓｉ（ＣＨ₃）₂−等の、１〜３個のアクリロイロキシ基又はメタクリロイロキシ基で置換された炭素原子数１〜１０、好ましくは２〜６のアルキル基、アリールオキシ置換アルキル基、ジオルガノシリル基に結合したアルキル基などが挙げられるが、好ましくは、ＣＨ₂＝ＣＨＣＯＯＣＨ₂ＣＨ₂−、（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂）₃Ｃ−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）₃Ｃ−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）₂Ｃ（Ｃ₂Ｈ₅）ＣＨ₂−、ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂ＣＨ₂−、（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂）₂Ｃ（Ｃ₂Ｈ₅）−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂）ＣＨ−、ＣＨ₂＝ＣＨＣＯＯＣＨ₂ＣＨ（ＣＨ₂ＯＣ₆Ｈ₅）−、ＣＨ₂＝ＣＨＣＯＯＣＨ₂−Ｓｉ（ＣＨ₃）₂−、及びＣＨ₂＝ＣＨＣＯＯＣＨ₂ＣＨ₂ＣＨ₂−Ｓｉ（ＣＨ₃）₂−であり、更に好ましくは、（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂）₃Ｃ−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）₃Ｃ−ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）₂Ｃ（Ｃ₂Ｈ₅）ＣＨ₂−、（ＣＨ₂＝ＣＨＣＯＯＣＨ₂）（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯＣＨ₂）ＣＨ−である。
【００２０】
上記一般構造式（２）におけるＲ⁴は同一又は異種の炭素原子数１〜９、好ましくは１〜６の非置換又は置換の一価炭化水素基である。Ｒ⁴の一価炭化水素基の具体例としては、上述した一般構造式（１）におけるＲ¹と同様のものが挙げられるが、Ｒ¹の場合と同様に、Ｒ⁴の５０モル％以上がメチル基で、かつ２５モル％以下がフェニル基であるものが好ましい。
【００２１】
上記一般構造式（２）におけるＲ⁵は炭素原子数１〜１８、好ましくは１〜８の一価炭化水素基である。Ｒ⁵の一価炭化水素基の具体例としては、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ネオペンチル基等のアルキル基；シクロヘキシル基等のシクロアルキル基；フェニル基等のアリール基；アリル基、プロペニル基、ブテニル基等のアルケニル基等が挙げられるが、好ましくはアルケニル基等の脂肪族不飽和基を除くものが好適に使用される。
【００２２】
また、一般構造式（２）において、ｎは１〜３、ｍは０〜２で、かつ１≦ｎ＋ｍ≦３を満足する整数であるが、ｎ＝１の時Ｒ³は複数個（即ち、２又は３個）の（メタ）アクリロイル基を有することが好ましい。
【００２３】
上記一般構造式（１）の直鎖状オルガノポリシロキサンは、常温で流動性を維持し、良好な硬化性を得るために比較的重合度の低い、液状であることが好ましい。具体的には、２３℃における粘度が１００，０００ｍＰａ・ｓ以下（通常、１００〜１００，０００ｍＰａ・ｓ）であることが好ましく、特に、５００〜１０，０００ｍＰａ・ｓの範囲が好ましい。また、重合度が低すぎると得られる硬化物が脆くなり、強度が劣る可能性があることから、上記一般構造式（１）において、Ｌは８〜１０，０００、好ましくは４８〜１，０００、より好ましくは９８〜１，０００の整数である。一般構造式（１）で示されるオルガノポリシロキサンとしては、具体的に下記のものを例示することができる。
【００２４】
【化５】

【００２５】
【化６】

【００２６】
【化７】

【００２７】
【化８】

〔上記式（１）−１〜（１）−２７において、Ｙはアクリロイルオキシ基（ＣＨ₂＝ＣＨＣＯＯ−）、又はメタクリロイルオキシ基（ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯＯ−）を示し、Ｒ’はメチル基、フェニル基又は３，３，３−トリフルオロプロピル基を示し、ｐ、ｑ＋ｒ、Ｌはそれぞれ８〜１０，０００、好ましくは４８〜１，０００、より好ましくは９８〜１，０００の整数を示す。〕
【００２８】
前記オルガノポリシロキサンは感放射線性基として、−ＯＲ³基を有している〔即ち、分子鎖両末端の各々に少なくとも１個（好ましくは２〜９個）の（メタ）アクリロイル基を有している〕ので、紫外線等の放射線照射により容易に硬化するという特徴を持つものである。このオルガノポリシロキサンは単独で、又は２種以上組み合せて使用することができる。
【００２９】
上記一般構造式（３）で示される、分子側鎖に（即ち、ポリシロキサンを構成する分子主鎖途中のケイ素原子に結合する一価置換基として）複数の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサンにおいて、Ｒ¹は上記一般構造式（１）における炭素原子数１〜９の非置換又は置換の一価炭化水素基と同様のものである。また、Ｒ⁶は同一又は異種の、上記一般構造式（４）で表される基又はメチル基であり、Ｒ⁷は同一又は異種の、上記一般構造式（４）で表される基である。
【００３０】
上記一般構造式（４）中のＲ⁸はアクリロイルオキシ基又はメタクリロイルオキシ基とケイ素原子とを連結する二価炭化水素基であり、具体的には、例えば、メチレン基、エチレン基、プロピレン基等の通常、炭素数１〜６、好ましくは１〜４のアルキレン基が挙げられる。また、上記一般構造式（４）中のＲ⁹は水素原子又はメチル基である。
【００３１】
上記一般構造式（３）中、ｓ及びｔはｓ≧２、ｔ≧８、ｓ＋ｔ≧１０及び０．０５≦ｓ／（ｓ＋ｔ）≦０．５を満たす正の整数であり、ｓ＋ｔは好ましくは４８〜１，０００、より好ましくは９８〜１，０００の整数である。即ち、一般構造式（３）のジオルガノポリシロキサンは、（メタ）アクリロイルオキシ基含有基を有するジオルガノシロキサン単位を主鎖のジオルガノシロキサン単位全体に対して５〜５０モル％含有するものである。
【００３２】
一般構造式（３）のオルガノポリシロキサンとしては、具体的には、下記の化合物が例示される。
【００３３】
【化９】

（上記式中、Ｙは同一又は異種の、アクリロイルオキシ基又はメタアクリロイルオキシ基であり、ｓ及びｔは上記と同様である。）
【００３４】
また、一般構造式（３）のジオルガノポリシロキサンは、常温で流動性を維持するために２３℃における粘度が１００，０００ｍＰａ・ｓ以下（通常、１００〜１００，０００ｍＰａ・ｓ）であることが好ましく、特に、５００〜１０，０００ｍＰａ・ｓの範囲が好ましい。一般構造式（３）のオルガノポリシロキサンは単独で又は２種以上組み合せて使用することができる。
【００３５】
本発明の光ファイバのコア材となる紫外線硬化型樹脂組成物としては、上記一般構造式（１）で示される分子鎖両末端にそれぞれ少なくとも１個の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサン、及び上記一般構造式（３）で示される分子側鎖に複数の（メタ）アクリロイル基を含有する直鎖状のオルガノポリシロキサンから選択される１種又は２種以上の、（メタ）アクリロイル基含有オルガノポリシロキサンと、増感剤及び／又は光重合開始剤とを含有する紫外線硬化性オルガノポリシロキサン組成物を好適に使用することができる。なお、上記一般構造式（１）で示されるオルガノポリシロキサンにおいて、Ｒ³が１個の（メタ）アクリロイル基を有する一価有機基で、かつｎ＝１のものである場合（即ち、該オルガノポリシロキサンが分子鎖両末端に（メタ）アクリロイル基をそれぞれ１個ずつ有するものである場合）には、一般構造式（１）で示される該オルガノポリシロキサンと一般構造式（３）で示される分子側鎖に（メタ）アクリロイル基を有するオルガノポリシロキサンとを、重量比で通常１００：５〜２００、好ましくは１００：１０〜１００程度の割合で併用することが流動性及び硬化物の機械的強度の点から望ましい。
【００３６】
ここで、上記増感剤（又は光重合開始剤）は、前記オルガノポリシロキサンのアクリロキシ基又はメタクリロキシ基の紫外線照射による架橋重合を促進させるための触媒である。
【００３７】
この場合、増感剤（又は光重合開始剤）としては、それ自体が開裂してラジカルを発生するものや、芳香族ケトンと水素供与体とを組み合せて複合的に用いるものが使用される。前者の例としては、例えば、ベンゾインイソブチルエーテル、１−ヒドロキシシクロヘキシルフェニルケトン、２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン、２，４，６−トリメチルベンゾイルジフェニルホスフィンオキサイド、２−ベンジル−２−ジメチルアミノ−１−（４−モルフォリノフェニル）−ブタノン等を挙げることができる。後者の例の芳香族ケトンとしては、例えば、ベンゾフェノン、４−フェニルベンゾフェノン、２−イソプロピルチオキサントン等が挙げられ、これらと組み合せる水素供与体としては、例えば、メチルジエタノールアミン、トリエタノールアミン、ｐ−ジメチルアミノアセトフェノン、ｐ−ジメチルアミノ安息香酸エチル、４，４’−ビス（ジエチルアミノ）ベンゾフェノン等のアミン化合物が挙げられる。
【００３８】
上記増感剤（又は光重合開始剤）は１種単独で、又は２種以上を組み合せて使用してもよい。また、増感剤（又は光重合開始剤）の配合量は、前記オルガノポリシロキサン１００重量部に対して、好ましくは０．５〜１０重量部、更に好ましくは１〜５重量部である。
【００３９】
本発明の紫外線硬化型樹脂組成物は、本発明の効果が損なわれない限りにおいて、上述した成分以外に、例えば、熱重合禁止剤、酸化防止剤、紫外線吸収剤、フローコントロール剤、接着促進剤等、公知の添加剤を適宜配合することができる。
【００４０】
本発明のクラッドを形成する樹脂は、コアとなる紫外線硬化型樹脂組成物の硬化物より屈折率が低ければこれも特に限定されるものではないが、上記紫外線硬化型樹脂組成物の硬化物よりも低屈折率な熱可塑性又は熱硬化性のフッ素系樹脂やフッ素変性された樹脂が好ましい。
【００４１】
クラッド材として用いられるフッ素系樹脂又はフッ素変性された樹脂としては、例えば、ポリテトラフルオロエチレン、テトラフルオロエチレン／パーフルオロアルキルビニルエーテル共重合体、テトラフルオロエチレン／ヘキサフルオロプロピレン共重合体、ポリクロロトリフルオロエチレン、テトラフルオロエチレン／エチレン共重合体、ポリビニルフルオライド、ポリビニリデンフルオライド、テトラフルオロエチレン／ビニリデンフルオライド共重合体等が挙げられる。
【００４２】
本発明のプラスチック光ファイバの作成方法としては、管状クラッドは、溶融押出法で、押出、冷却条件等を制御することによって製造することができる。管状クラッドの厚さは、特に限定はないが、プラスチック光ファイバの外径変動への影響又は可撓性の点から、０．２５〜２ｍｍ程度が好ましい。続いて更に、コア材として未硬化の紫外線硬化型樹脂組成物を上記管状クラッド内に導入し、紫外線照射により硬化させて光ファイバを得ることができる。この場合、樹脂組成物としては、室温（２３℃）で液状であることが好ましい。
【００４３】
【実施例】
以下、実施例と比較例を示し本発明を具体的に説明するが、本発明は下記の実施例に制限されるものではない。なお、下記の例において部は重量部を示す。
【００４４】
［実施例１］
下記平均構造式（５）
【化１０】

で表される２３℃の粘度が１，３００ｍＰａ・ｓであるオルガノポリシロキサン１００部に２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン２部と、２，４，６−トリメチルベンゾイルジフェニルフォスフィンオキサイド１部とを添加混合し、紫外線硬化型オルガノポリシロキサン組成物を得た。
【００４５】
この組成物を、内径２ｍｍ，外径３ｍｍのＦＥＰチューブに導入した。導入後、チューブ端末を封止し、８０Ｗ／ｃｍ²のメタルハライド水銀灯２灯を備えるコンベア炉内で１０秒間ＵＶ照射（エネルギー量：４０００ｍＪ）して光ファイバ１を得た。
【００４６】
［実施例２］
下記平均構造式（６）
【化１１】

で表される２３℃の粘度が３，０００ｍＰａ・ｓであるオルガノポリシロキサン８０部に下記平均構造式（７）
【化１２】

で表される２３℃の粘度が１，２００ｍＰａ・ｓであるオルガノポリシロキサン２０部、光重合開始剤として下記構造式（８）
【化１３】

で表される化合物３部とを添加混合し、紫外線硬化型オルガノポリシロキサン組成物を得た。
【００４７】
この組成物を実施例１と同様に、内径２ｍｍ，外径３ｍｍのＦＥＰチューブに導入した。導入後、チューブ端末を封止し、８０Ｗ／ｃｍ²のメタルハライド水銀灯２灯を備えるコンベア炉内で１０秒間ＵＶ照射（エネルギー量：４０００ｍＪ）して光ファイバ２を得た。
【００４８】
［実施例３］
メルトフローレート１０ｇ／１０ｍｉｎのＦＥＰを内径２５ｍｍφ、Ｌ／Ｄ＝２２の押出し機で、３３０℃にて、内径２ｍｍ，外径３ｍｍのチューブを押出し、成形した。押出しが安定したところで、その押出し機クロスヘッドのダイの中央に配置したマンドレルより、上記平均構造式（５）で表されるオルガノポリシロキサン１００部に２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン２部と、２，４，６−トリメチルベンゾイルジフェニルフォスフィンオキサイド１部とを添加混合して得られる紫外線硬化型オルガノポリシロキサン組成物を、０．５ｋｇ／ｃｍ²の圧力を加えながら注入した。更に、押出し機の下に連続的に配置された、８０Ｗ／ｃｍ²のメタルハライド水銀灯２灯を備える円筒型ＵＶ硬化炉内で、１０秒間ＵＶ照射（エネルギー量：４０００ｍＪ）して光ファイバ３を得た。
【００４９】
［比較例１］
下記平均構造式（９）
【化１４】

で表される２３℃の粘度が９００ｍＰａ・ｓであるオルガノポリシロキサン１００部に、下記平均構造式（１０）
【化１５】

で表されるオルガノハイドロジェンポリシロキサン２．５部、塩化白金酸（２エチルヘキシルアルコール溶液２％）０．１部、１，３，５，７−テトラメチル−１，３，５，７−テトラビニルシクロテトラシロキサン０．１５部とを添加混合し、熱硬化型（ヒドロシリル化付加反応硬化型）オルガノポリシロキサン組成物を得た。
【００５０】
この組成物を、内径２ｍｍ，外径３ｍｍのＦＥＰチューブに導入した。導入後、チューブ端末を封止し、１５０℃で３０分間、加熱熱風炉内で硬化させ、光ファイバ４を得た。
【００５１】
この光ファイバ４は室温にて観察したところ、コア材の収縮が大きかったためＦＥＰチューブとコアのシリコーン硬化物の界面で剥離し、コアとクラッドの間に空間が入ったものとなった。
【００５２】
［比較例２］
メルトフローレート１０ｇ／１０ｍｉｎのＦＥＰを内径２５ｍｍφ、Ｌ／Ｄ＝２２の押出し機で、３３０℃にて、内径２ｍｍ，外径３ｍｍのチューブを押出し成形した。押出しが安定したところで、その押出し機クロスヘッドのダイの中央に配置したマンドレルより、上記平均構造式（９）で表されるオルガノポリシロキサン１００部に、上記平均構造式（１０）で表されるオルガノハイドロジェンポリシロキサン２．５部、塩化白金酸（２エチルヘキシルアルコール溶液２％）０．１部、１，３，５，７−テトラメチル−１，３，５，７−テトラビニルシクロテトラシロキサン０．１５部とを添加混合して得られる熱硬化型（ヒドロシリル化付加反応硬化型）オルガノポリシロキサン組成物を、２ｋｇ／ｃｍ²の圧力を加えながら注入を試みたが、オルガノポリシロキサン組成物は注入部で硬化し、光ファイバは得られなかった。
【００５３】
得られた光ファイバ１〜４の特性を測定した。
［伝送損失］
光伝送性能の評価は、ハロゲンランプの光源をモノクロメーターで分光し、６６０ｎｍの光を用いて行なった。得られたファイバの一端から光を入射し、出射光の光量を測定した。長さＬ₁（ｍ）のファイバの光量Ｐ₁（Ｗ）を測定した後、ファイバをＬ₂（ｍ）にカットして光量Ｐ₂（Ｗ）を測定した。この差を用いて計算を行なうカットバック法により、伝送損失を求めた。
【００５４】
この場合、波長６６０ｎｍ、Ｌ₁＝５ｍ、Ｌ₂＝１ｍで測定を行なった。伝送損失ａ（ｄＢ／ｍ）は、次式で示される。
ａ＝１０Ｌｏｇ（Ｐ₂／Ｐ₁）／（Ｌ₁−Ｌ₂）
【００５５】
【表１】

【００５６】
【発明の効果】
本発明によれば、コアとして紫外線硬化型樹脂組成物の硬化物を用いることで、クラッドにコア材を充容し、紫外線硬化することで、コアとクラッドとが一体となった光ファイバを得ることができ、この光ファイバは、伝送損失が小さく、電気機器、自動車などの短距離伝送用の光伝送路に好適に用いられる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic optical fiber using a thermoplastic or thermosetting resin as a cladding and a cured product of an ultraviolet curable resin composition as a core, and a method for manufacturing the same.
[0002]
[Prior art and problems to be solved by the invention]
Plastic optical fiber has high transmission loss, but has a large aperture coefficient, flexibility, and good terminal processability, so it is expected as an optical transmission line for short-distance transmission in automobiles, electronic devices, etc. Has been.
[0003]
Conventionally, plastic optical fiber cores have been made of acrylic resin such as polymethyl methacrylate. However, due to demands for improved heat resistance, cores made of organopolysiloxane with higher heat resistance have been formed. JP-A-60-42712, JP-A-60-43613, JP-A-61-254625, JP-A-61-275706, JP-A-63-121004, JP-A-63- No. 253303, Japanese Patent Publication No. 6-54363, Japanese Patent Laid-Open No. 8-152543, Japanese Patent Laid-Open No. 8-33914, and Japanese Patent No. 3179000).
[0004]
Plastic optical fibers using these as core materials have the advantage that they are rich in flexibility and excellent in heat resistance as compared with those using polymethyl methacrylate as a core component.
[0005]
These organopolysiloxane compositions are mainly composed of an organopolysiloxane containing an alkenyl group (for example, a vinyl group), an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom, and a platinum compound. A reaction mechanism is adopted in which the hydrogen atom of the organohydrogenpolysiloxane is added to the alkenyl group of the group-containing organopolysiloxane by a catalytic action of a platinum compound and cured by an addition reaction (hydrosilylation reaction).
[0006]
However, this cured type is hardened or gelled by the high-temperature cured product being colored by decomposition of the platinum compound, causing optical transmission loss, or being heated during the molding of the resin that becomes the cladding. Simultaneous molding was impossible due to thickening.
[0007]
In addition to the reaction mechanism of curing by addition reaction (hydrosilylation reaction), a method using a phosphorus-containing organopolysiloxane as disclosed in Japanese Patent No. 2924515, and an acrylic modified silicone monomer as disclosed in Japanese Patent Laid-Open No. 8-313735. However, it is difficult to mold the core material at the same time as the clad molding, and after the clad material is molded, the core material is filled and cured. Alternatively, there was no other way to coat the clad material after molding the core material.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plastic optical fiber with good productivity capable of simultaneously molding a clad and a core and a method for manufacturing the same.
[0009]
Means for Solving the Problem and Embodiment of the Invention
  As a result of intensive studies to achieve the above object, the present inventor uses a thermoplastic or thermosetting resin as a cladding, and as a core material,A linear organopolysiloxane containing at least two (meth) acryloyl groups at both ends of the molecular chain represented by the following general structural formula (1), and a molecule represented by the following general structural formula (3) One or more (meth) acryloyl group-containing organopolysiloxanes selected from linear organopolysiloxanes containing a plurality of (meth) acryloyl groups in the side chainBy using a UV curable resin composition containing a sensitizer and / or a photopolymerization initiator as a base polymer, and curing the core material by irradiating with UV rays to produce a clad and a core integrally. The present inventors have found that a high-performance plastic optical fiber with a small transmission loss can be efficiently produced, and have made the present invention.
[0010]
  Therefore, the present invention provides an optical fiber in which a tubular clad is made of a thermoplastic or thermosetting resin, and a solid core having a refractive index higher than that of the clad is filled therein.The following general structural formula (1):
Embedded image

[In the formula, R ¹ Represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 9 carbon atoms, and X represents the following general structural formula (2):
Embedded image

(Wherein R ² Is a divalent hydrocarbon group having 2 to 4 carbon atoms or an oxygen atom, and R ^Three Is a monovalent organic group having 4 to 25 carbon atoms having 1 to 3 (meth) acryloyl groups, and R ^Four Are the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 9 carbon atoms, R ^Five Are the same or different monovalent hydrocarbon groups having 1 to 18 carbon atoms. N is an integer satisfying 1 to 3, m is 0 to 2, and 1 ≦ n + m ≦ 3. ^Three Has 2 or 3 (meth) acryloyl groups. )
L is an integer of 8 to 10,000. ]
A linear organopolysiloxane containing at least two (meth) acryloyl groups at both ends of the molecular chain represented by the following general formula (3):
Embedded image

[In the formula, R ¹ Is the same as described above, and R ⁶ Are the same or different general structural formula (4):
Embedded image

(Wherein R ⁸ Is a divalent hydrocarbon group and R ⁹ Is a hydrogen atom or a methyl group. )
Or a methyl group represented by ⁷ Are groups represented by the same or different general structural formula (4), and s and t are positive integers satisfying s + t ≧ 10 and 0.05 ≦ s / (s + t) ≦ 0.5. ]
One or more (meth) acryloyl group-containing organopolysiloxanes selected from linear organopolysiloxanes containing a plurality of (meth) acryloyl groups in the molecular side chainA plastic optical fiber, and a thermoplastic or thermosetting resin, characterized by using an ultraviolet-cured product of an ultraviolet-curing resin composition containing a sensitizer and / or a photopolymerization initiator as a base polymer A cured product having a higher refractive index than the clad is provided inside the tubular clad.A small amount at both ends of the molecular chain represented by the general structural formula (1) A linear organopolysiloxane containing at least two (meth) acryloyl groups and a straight chain containing a plurality of (meth) acryloyl groups in the molecular side chain represented by the above general structural formula (3) One or two or more (meth) acryloyl group-containing organopolysiloxanes selected from the shaped organopolysiloxanesIs added as a base polymer and further filled with an ultraviolet curable resin composition containing a sensitizer and / or a photopolymerization initiator, and then the composition is irradiated with ultraviolet rays from the outside of the cladding through the cladding. A plastic optical fiber manufacturing method is provided, in which a core is manufactured integrally with the clad by curing.
[0011]
  Hereinafter, the present invention will be described in more detail.
  The optical fiber of the present invention includes a transparent core and a transparent tubular clad covering the core, and the core has a refractive index larger than that of the tubular clad.
[0012]
In this case, the core is composed of a cured product of an ultraviolet curable resin composition, and the ultraviolet curable resin composition is mainly composed of a transparent resin that undergoes an ultraviolet curing reaction, and is a sensitizer and / or light. It contains a polymerization initiator.
[0013]
Here, the resin used as the core is not particularly limited as long as it is a transparent resin that cures with ultraviolet rays, but an organopolysiloxane (silicone) resin or urethane having an acrylic functional group containing a sensitizer. Examples thereof include organopolysiloxane (silicone) resins and urethane resins containing a resin and a cationic photopolymerization initiator. In particular, an organopolysiloxane (silicone) resin is preferable because it is excellent in heat resistance and weather resistance, and an ultraviolet curable organopolysiloxane composition is preferable as the ultraviolet curable resin composition.
[0014]
Examples of the ultraviolet curable organopolysiloxane (silicone) resin composition include acrylic functional groups such as JP-B-4-25231, JP-B-6-8335, JP-B-6-17435, and JP-B-6-27162. And a silicone resin composition having a mercapto group proposed in Japanese Patent No. 1530580, Japanese Patent No. 2731932, Japanese Patent No. 2516897, and the like. Especially, the silicone resin composition which has an acrylic functional group does not have a strange odor like the silicone resin composition which has a mercapto group, and can be used conveniently. As the acrylic functional group-containing organopolysiloxane as the main agent (base polymer) constituting the organopolysiloxane (silicone) resin composition having these acrylic functional groups, for example, the following general structural formula (1):
[Chemical 1]

[In the formula, R¹Represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 9 carbon atoms, and X represents the following general structural formula (2):
[Chemical 2]

(Wherein R²Is a divalent hydrocarbon group having 2 to 4 carbon atoms or an oxygen atom, and R^ThreeIs a monovalent organic group having 4 to 25 carbon atoms having 1 to 3 (meth) acryloyl groups, R^FourAre the same or different monovalent hydrocarbon groups having 1 to 9 carbon atoms, and R^FiveAre the same or different monovalent hydrocarbon groups having 1 to 18 carbon atoms. N is an integer that satisfies 1 to 3, m is 0 to 2, and satisfies 1 ≦ n + m ≦ 3. L is an integer of 8 to 10,000. ]
A linear organopolysiloxane containing at least one (meth) acryloyl group at both ends of the molecular chain represented by the following general formula (3):
[Chemical 3]

[In the formula, R¹Is the same as described above, and R⁶Are the same or different general structural formula (4):
[Formula 4]

(Wherein R⁸Is a divalent hydrocarbon group and R⁹Is a hydrogen atom or a methyl group. )
Or a methyl group represented by R⁷Are groups represented by the same or different general structural formula (4), and s and t are positive integers satisfying s + t ≧ 10 and 0.05 ≦ s / (s + t) ≦ 0.5. ]
The linear organopolysiloxane containing a plurality of (meth) acryloyl groups in the molecular side chain can be exemplified.
[0015]
Here, the organopolysiloxane is a component used as a base polymer, and one or more of the compounds represented by the general structural formulas (1) and / or (3) can be preferably used. .
[0016]
In the linear organopolysiloxane containing at least one (meth) acryloyl group at both ends of the molecular chain represented by the general structural formula (1), R¹Are the same or different monovalent hydrocarbon groups having 1 to 9, preferably 1 to 6 carbon atoms. This R¹Specific examples of the monovalent hydrocarbon group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group. Group, alkyl group such as nonyl group; cycloalkyl group such as cyclohexyl group and cycloheptyl group; alkenyl group such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group; phenyl group, tolyl group, etc. An aralkyl group such as a benzyl group, a phenylethyl group or a phenylpropyl group; or a chloro group in which at least a part of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with a substituent such as a halogen atom or a cyano group Examples include a methyl group, a cyanoethyl group, a trifluoropropyl group, and the like.¹In which 50 mol% or more (50 to 100 mol%, particularly 75 to 97 mol%) of the above is a methyl group and 25 mol% or less (0 to 25 mol%, particularly 3 to 20 mol%) is a phenyl group. preferable.
[0017]
In the general structural formula (1), X is a group represented by the general structural formula (2). R in the general structural formula (2)²Is a divalent hydrocarbon group having 2 to 4 carbon atoms or an oxygen atom, and is preferably a divalent hydrocarbon group from the viewpoint of water resistance. This R²Specific examples of the divalent hydrocarbon group include alkylene groups having 2 to 4 carbon atoms such as an ethylene group, a propylene group, a methylethylene group, and a tetramethylene group, with an ethylene group being preferred.
[0018]
R in the general structural formula (2)^ThreeIs a monovalent organic group having 4 to 25 carbon atoms and having 1 to 3, preferably 2 to 3, more preferably 3 (meth) acryloyl groups (particularly (meth) acryloyloxy groups). R^ThreeSpecific examples of the (meth) acryloyl group in₂= CHCOO-, CH₂= C (CH_Three) COO-, CH₂= CHCO-, CH₂= C (CH_Three) Acrylic functional group such as CO-, methacryl functional group and the like.
[0019]
R containing such a (meth) acryloyl group^ThreeSpecific examples of monovalent organic groups include CH₂= CHCOOCH₂CH₂-, (CH₂= C (CH_Three) COOCH₂)_ThreeC-CH₂-, (CH₂= CHCOOCH₂)_ThreeC-CH₂-, (CH₂= CHCOOCH₂)₂C (C₂H_Five) CH₂-, CH₂= CHCOOCH₂CH (CH₂OC₆H_Five)-, CH₂= CHCOOCH₂-Si (CH_Three)₂-, CH₂= CHCOOCH₂CH₂CH₂-Si (CH_Three)₂Alkyl bonded to 1 to 3 carbon atoms, preferably 2 to 6 alkyl groups, aryloxy substituted alkyl groups, diorganosilyl groups substituted with 1 to 3 acryloyloxy groups or methacryloyloxy groups, such as- Group, etc., preferably CH₂= CHCOOCH₂CH₂-, (CH₂= C (CH_Three) COOCH₂)_ThreeC-CH₂-, (CH₂= CHCOOCH₂)_ThreeC-CH₂-, (CH₂= CHCOOCH₂)₂C (C₂H_Five) CH₂-, CH₂= C (CH_Three) COOCH₂CH₂-, (CH₂= C (CH_Three) COOCH₂)₂C (C₂H_Five) -CH₂-, (CH₂= CHCOOCH₂) (CH₂= C (CH_Three) COOCH₂) CH-, CH₂= CHCOOCH₂CH (CH₂OC₆H_Five)-, CH₂= CHCOOCH₂-Si (CH_Three)₂-And CH₂= CHCOOCH₂CH₂CH₂-Si (CH_Three)₂-, More preferably (CH₂= C (CH_Three) COOCH₂)_ThreeC-CH₂-, (CH₂= CHCOOCH₂)_ThreeC-CH₂-, (CH₂= CHCOOCH₂)₂C (C₂H_Five) CH₂-, (CH₂= CHCOOCH₂) (CH₂= C (CH_Three) COOCH₂) CH-.
[0020]
R in the general structural formula (2)^FourAre the same or different monovalent hydrocarbon groups having 1 to 9, preferably 1 to 6 carbon atoms. R^FourSpecific examples of the monovalent hydrocarbon group include R in the general structural formula (1) described above.¹Are the same, but R¹As in the case of R^FourOf these, those in which 50 mol% or more of them are methyl groups and 25 mol% or less are phenyl groups are preferred.
[0021]
R in the general structural formula (2)^FiveIs a monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 8 carbon atoms. R^FiveSpecific examples of monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and neopentyl groups; cycloalkyl groups such as cyclohexyl groups; aryl groups such as phenyl groups; Group, propenyl group, alkenyl group such as butenyl group and the like can be mentioned, but those excluding aliphatic unsaturated groups such as alkenyl group are preferably used.
[0022]
In the general structural formula (2), n is 1 to 3, m is 0 to 2, and 1 ≦ n + m ≦ 3, but when n = 1, R^ThreePreferably has a plurality of (ie, 2 or 3) (meth) acryloyl groups.
[0023]
The linear organopolysiloxane of the general structural formula (1) is preferably a liquid having a relatively low degree of polymerization in order to maintain fluidity at normal temperature and obtain good curability. Specifically, the viscosity at 23 ° C. is preferably 100,000 mPa · s or less (usually 100 to 100,000 mPa · s), and particularly preferably in the range of 500 to 10,000 mPa · s. Further, if the degree of polymerization is too low, the resulting cured product becomes brittle and the strength may be inferior. Therefore, in the general structural formula (1), L is 8 to 10,000, preferably 48 to 1,000. More preferably, it is an integer of 98 to 1,000. Specific examples of the organopolysiloxane represented by the general structural formula (1) include the following.
[0024]
[Chemical formula 5]

[0025]
[Chemical 6]

[0026]
[Chemical 7]

[0027]
[Chemical 8]

[In the above formulas (1) -1 to (1) -27, Y represents an acryloyloxy group (CH₂= CHCOO-) or a methacryloyloxy group (CH₂= C (CH_Three) COO-), R 'represents a methyl group, a phenyl group or a 3,3,3-trifluoropropyl group, p, q + r and L are each 8 to 10,000, preferably 48 to 1,000, More preferably, an integer of 98 to 1,000 is shown. ]
[0028]
The organopolysiloxane has -OR as a radiation sensitive group.^ThreeSince it has a group [that is, it has at least one (preferably 2 to 9) (meth) acryloyl group at each of both ends of the molecular chain], it is easily cured by irradiation with ultraviolet rays or the like. It has the characteristic of doing. These organopolysiloxanes can be used alone or in combination of two or more.
[0029]
A straight chain containing a plurality of (meth) acryloyl groups in the molecular side chain represented by the general structural formula (3) (that is, as a monovalent substituent bonded to a silicon atom in the middle of the molecular main chain constituting the polysiloxane). In the chain organopolysiloxane, R¹Is the same as the unsubstituted or substituted monovalent hydrocarbon group having 1 to 9 carbon atoms in the general structural formula (1). R⁶Are the same or different groups represented by the above general structural formula (4) or methyl groups, and R⁷Are the same or different groups represented by the above general structural formula (4).
[0030]
R in the general structural formula (4)⁸Is a divalent hydrocarbon group linking an acryloyloxy group or a methacryloyloxy group and a silicon atom. Specifically, for example, a methylene group, an ethylene group, a propylene group or the like usually has 1 to 6 carbon atoms, preferably 1-4 alkylene groups are mentioned. In addition, R in the general structural formula (4)⁹Is a hydrogen atom or a methyl group.
[0031]
In the general structural formula (3), s and t are positive integers satisfying s ≧ 2, t ≧ 8, s + t ≧ 10 and 0.05 ≦ s / (s + t) ≦ 0.5, and s + t is preferably It is an integer of 48 to 1,000, more preferably 98 to 1,000. That is, the diorganopolysiloxane of the general structural formula (3) contains 5 to 50 mol% of the diorganosiloxane unit having a (meth) acryloyloxy group-containing group with respect to the whole diorganosiloxane unit of the main chain. is there.
[0032]
Specific examples of the organopolysiloxane of the general structural formula (3) include the following compounds.
[0033]
[Chemical 9]

(In the above formula, Y is the same or different acryloyloxy group or methacryloyloxy group, and s and t are the same as above.)
[0034]
In addition, the diorganopolysiloxane of the general structural formula (3) has a viscosity at 23 ° C. of 100,000 mPa · s or less (usually 100 to 100,000 mPa · s) in order to maintain fluidity at room temperature. The range of 500 to 10,000 mPa · s is particularly preferable. The organopolysiloxane of the general structural formula (3) can be used alone or in combination of two or more.
[0035]
As the ultraviolet curable resin composition that becomes the core material of the optical fiber of the present invention, the linear chain containing at least one (meth) acryloyl group at each of both ends of the molecular chain represented by the general structural formula (1). And one or more selected from linear organopolysiloxanes containing a plurality of (meth) acryloyl groups in the molecular side chain represented by the general structural formula (3) ( An ultraviolet curable organopolysiloxane composition containing a (meth) acryloyl group-containing organopolysiloxane and a sensitizer and / or a photopolymerization initiator can be suitably used. In the organopolysiloxane represented by the general structural formula (1), R^ThreeIs a monovalent organic group having one (meth) acryloyl group and n = 1 (that is, the organopolysiloxane has one (meth) acryloyl group at both ends of the molecular chain. In the case where the organic polysiloxane has a (meth) acryloyl group in the molecular side chain represented by the general structural formula (3) and the organopolysiloxane represented by the general structural formula (1), the weight ratio In general, it is desirable to use them together in a ratio of about 100: 5 to 200, preferably about 100: 10 to 100, from the viewpoint of fluidity and mechanical strength of the cured product.
[0036]
Here, the sensitizer (or photopolymerization initiator) is a catalyst for accelerating the crosslinking polymerization of the acryloxy group or methacryloxy group of the organopolysiloxane by ultraviolet irradiation.
[0037]
In this case, as the sensitizer (or photopolymerization initiator), one that cleaves itself to generate a radical, or one that uses a combination of an aromatic ketone and a hydrogen donor is used. Examples of the former include, for example, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2- And benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone. Examples of the aromatic ketone in the latter example include benzophenone, 4-phenylbenzophenone, 2-isopropylthioxanthone and the like, and examples of the hydrogen donor to be combined with these include, for example, methyldiethanolamine, triethanolamine, p-dimethyl. Examples include amine compounds such as aminoacetophenone, ethyl p-dimethylaminobenzoate, and 4,4′-bis (diethylamino) benzophenone.
[0038]
The above sensitizers (or photopolymerization initiators) may be used alone or in combination of two or more. Moreover, the compounding quantity of a sensitizer (or photoinitiator) becomes like this. Preferably it is 0.5-10 weight part with respect to 100 weight part of said organopolysiloxane, More preferably, it is 1-5 weight part.
[0039]
As long as the effect of the present invention is not impaired, the ultraviolet curable resin composition of the present invention is, for example, a thermal polymerization inhibitor, an antioxidant, an ultraviolet absorber, a flow control agent, an adhesion promoter, in addition to the components described above. A known additive can be appropriately blended.
[0040]
The resin forming the clad of the present invention is not particularly limited as long as the refractive index is lower than that of the cured product of the ultraviolet curable resin composition serving as the core. In particular, a thermoplastic or thermosetting fluorine resin or fluorine-modified resin having a low refractive index is preferable.
[0041]
Examples of the fluorine-based resin or fluorine-modified resin used as the cladding material include polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, and polychlorotriethylene. Examples thereof include fluoroethylene, tetrafluoroethylene / ethylene copolymer, polyvinyl fluoride, polyvinylidene fluoride, and tetrafluoroethylene / vinylidene fluoride copolymer.
[0042]
As a method for producing the plastic optical fiber of the present invention, the tubular clad can be produced by controlling extrusion, cooling conditions and the like by a melt extrusion method. The thickness of the tubular clad is not particularly limited, but is preferably about 0.25 to 2 mm from the viewpoint of influence on the outer diameter variation of the plastic optical fiber or flexibility. Subsequently, an uncured ultraviolet curable resin composition as a core material can be further introduced into the tubular clad and cured by ultraviolet irradiation to obtain an optical fiber. In this case, the resin composition is preferably liquid at room temperature (23 ° C.).
[0043]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following examples, parts indicate parts by weight.
[0044]
[Example 1]
The following average structural formula (5)
[Chemical Formula 10]

2 parts of 2-hydroxy-2-methyl-1-phenylpropan-1-one and 2,4,6-trimethylbenzoyl are added to 100 parts of an organopolysiloxane having a viscosity of 1,300 mPa · s at 23 ° C. One part of diphenylphosphine oxide was added and mixed to obtain an ultraviolet curable organopolysiloxane composition.
[0045]
This composition was introduced into an FEP tube having an inner diameter of 2 mm and an outer diameter of 3 mm. After the introduction, the tube terminal is sealed and 80 W / cm²The optical fiber 1 was obtained by UV irradiation (energy amount: 4000 mJ) for 10 seconds in a conveyor furnace equipped with two metal halide mercury lamps.
[0046]
[Example 2]
The following average structural formula (6)
Embedded image

The following average structural formula (7) is added to 80 parts of an organopolysiloxane having a viscosity of 3,000 mPa · s at 23 ° C.
Embedded image

20 parts of an organopolysiloxane having a viscosity of 1,200 mPa · s at 23 ° C. represented by the following structural formula (8)
Embedded image

Then, 3 parts of the compound represented by the formula (1) was added and mixed to obtain an ultraviolet curable organopolysiloxane composition.
[0047]
As in Example 1, this composition was introduced into an FEP tube having an inner diameter of 2 mm and an outer diameter of 3 mm. After the introduction, the tube terminal is sealed and 80 W / cm²The optical fiber 2 was obtained by UV irradiation (energy amount: 4000 mJ) for 10 seconds in a conveyor furnace equipped with two metal halide mercury lamps.
[0048]
[Example 3]
A tube having an inner diameter of 2 mm and an outer diameter of 3 mm was extruded and molded at 330 ° C. using an extruder having an inner diameter of 25 mmφ and L / D = 22 of FEP having a melt flow rate of 10 g / 10 min. When the extrusion was stabilized, 2-hydroxy-2-methyl-1-phenylpropane was added to 100 parts of the organopolysiloxane represented by the above average structural formula (5) from the mandrel placed at the center of the die of the extruder crosshead. An ultraviolet curable organopolysiloxane composition obtained by adding and mixing 2 parts of -1-one and 1 part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 0.5 kg / cm²It was injected while applying the pressure of. In addition, 80 W / cm, continuously placed under the extruder²The optical fiber 3 was obtained by UV irradiation (energy amount: 4000 mJ) for 10 seconds in a cylindrical UV curing furnace equipped with two metal halide mercury lamps.
[0049]
[Comparative Example 1]
The following average structural formula (9)
Embedded image

The following average structural formula (10) is added to 100 parts of an organopolysiloxane having a viscosity of 900 mPa · s at 23 ° C.
Embedded image

2.5 parts of an organohydrogenpolysiloxane, 0.1 part of chloroplatinic acid (2-ethylhexyl alcohol solution 2%), 1,3,5,7-tetramethyl-1,3,5,7-tetra 0.15 parts of vinylcyclotetrasiloxane was added and mixed to obtain a thermosetting (hydrosilylation addition reaction curing type) organopolysiloxane composition.
[0050]
This composition was introduced into an FEP tube having an inner diameter of 2 mm and an outer diameter of 3 mm. After the introduction, the tube terminal was sealed and cured in a heated hot air oven at 150 ° C. for 30 minutes to obtain an optical fiber 4.
[0051]
When this optical fiber 4 was observed at room temperature, the core material was greatly shrunk and peeled off at the interface between the FEP tube and the cured silicone product of the core, resulting in a space between the core and the clad.
[0052]
[Comparative Example 2]
A tube having an inner diameter of 2 mm and an outer diameter of 3 mm was extrusion-molded at 330 ° C. with an extruder having a melt flow rate of 10 g / 10 min and an FEP having an inner diameter of 25 mmφ and L / D = 22. When the extrusion is stable, from the mandrel placed in the center of the die of the extruder crosshead, 100 parts of the organopolysiloxane represented by the above average structural formula (9) is represented by the above average structural formula (10). 2.5 parts of organohydrogenpolysiloxane, 0.1 part of chloroplatinic acid (2-ethylhexyl alcohol solution 2%), 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane A thermosetting (hydrosilylation addition reaction curing type) organopolysiloxane composition obtained by adding and mixing 0.15 part is 2 kg / cm.²However, the organopolysiloxane composition was cured at the injection portion, and no optical fiber was obtained.
[0053]
The characteristics of the obtained optical fibers 1 to 4 were measured.
[Transmission loss]
The light transmission performance was evaluated by using a light of 660 nm by spectrally dividing the light source of the halogen lamp with a monochromator. Light was incident from one end of the obtained fiber, and the amount of emitted light was measured. Length L₁(M) Fiber light quantity P₁After measuring (W), the fiber is L₂Cut to (m) and light quantity P₂(W) was measured. The transmission loss was obtained by a cutback method in which calculation was performed using this difference.
[0054]
In this case, the wavelength is 660 nm, L₁= 5m, L₂= 1 m. Transmission loss a (dB / m) is expressed by the following equation.
a = 10 Log (P₂/ P₁) / (L₁-L₂)
[0055]
[Table 1]

[0056]
【The invention's effect】
According to the present invention, by using a cured product of an ultraviolet curable resin composition as a core, the core material is filled in the clad and cured by ultraviolet to obtain an optical fiber in which the core and the clad are integrated. This optical fiber has a small transmission loss and is preferably used for an optical transmission line for short-distance transmission such as electrical equipment and automobiles.

Claims (8)

In an optical fiber in which a tubular clad is made of a thermoplastic or thermosetting resin and a solid core having a higher refractive index than the clad is filled therein, the core has the following general structural formula (1):

[Wherein R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 9 carbon atoms, and X represents the following general structural formula (2):

(In the formula, R ² is a divalent hydrocarbon group having 2 to 4 carbon atoms or an oxygen atom, and R ³ is a monovalent organic having 4 to 25 carbon atoms having 1 to 3 (meth) acryloyl groups). R ⁴ is the same or different monovalent hydrocarbon group having 1 to 9 carbon atoms and is unsubstituted or substituted, and R ⁵ is the same or different monovalent hydrocarbon group having 1 to 18 carbon atoms. N is an integer satisfying 1 to 3, m is 0 to 2, and 1 ≦ n + m ≦ 3, and when n is 1, R ³ is 2 or 3 (meth) acryloyl groups. Have
L is an integer of 8 to 10,000. ]
A linear organopolysiloxane containing at least two (meth) acryloyl groups at both ends of the molecular chain represented by the following general formula (3):

[Wherein, R ¹ is the same as described above, and R ⁶ is the same or different from the following general structural formula (4):

(In the formula, R ⁸ is a divalent hydrocarbon group, and R ⁹ is a hydrogen atom or a methyl group.)
R ⁷ is a group represented by the same or different general structural formula (4), and s and t are s + t ≧ 10 and 0.05 ≦ s / (s + t ) Is a positive integer satisfying ≦ 0.5. ]
1 or 2 or more types of (meth) acryloyl group-containing organopolysiloxane selected from linear organopolysiloxanes containing a plurality of (meth) acryloyl groups in the molecular side chain A plastic optical fiber using an ultraviolet-cured product of an ultraviolet-curable resin composition further comprising a sensitizer and / or a photopolymerization initiator.   The plastic optical fiber according to claim 1, wherein the ultraviolet curable resin composition is liquid at room temperature (23 ° C).   The plastic optical fiber according to claim 1 or 2, wherein the tubular cladding has a thickness of 0.25 to 2 mm. The plastic optical fiber according to any one of claims 1 to 3 , wherein the clad material is a thermoplastic or thermosetting fluororesin. The following general structural formula (1) that gives a cured product having a higher refractive index than the clad inside the tubular clad made of thermoplastic or thermosetting resin :

[Wherein R ¹ represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 9 carbon atoms, and X represents the following general structural formula (2):

(In the formula, R ² is a divalent hydrocarbon group having 2 to 4 carbon atoms or an oxygen atom, and R ³ is a monovalent organic having 4 to 25 carbon atoms having 1 to 3 (meth) acryloyl groups). R ⁴ is the same or different monovalent hydrocarbon group having 1 to 9 carbon atoms and is unsubstituted or substituted, and R ⁵ is the same or different monovalent hydrocarbon group having 1 to 18 carbon atoms. N is an integer satisfying 1 to 3, m is 0 to 2, and 1 ≦ n + m ≦ 3, and when n is 1, R ³ is 2 or 3 (meth) acryloyl groups. Have
L is an integer of 8 to 10,000. ]
A linear organopolysiloxane containing at least two (meth) acryloyl groups at both ends of the molecular chain represented by the following general formula (3):

[Wherein, R ¹ is the same as described above, and R ⁶ is the same or different from the following general structural formula (4):

(In the formula, R ⁸ is a divalent hydrocarbon group, and R ⁹ is a hydrogen atom or a methyl group.)
R ⁷ is a group represented by the same or different general structural formula (4), and s and t are s + t ≧ 10 and 0.05 ≦ s / (s + t ) Is a positive integer satisfying ≦ 0.5. ]
1 or 2 or more types of (meth) acryloyl group-containing organopolysiloxane selected from linear organopolysiloxanes containing a plurality of (meth) acryloyl groups in the molecular side chain The composition is further filled with an ultraviolet curable resin composition containing a sensitizer and / or a photopolymerization initiator, and then the composition is cured by irradiating the composition with ultraviolet light from the outside of the cladding through the cladding. Thus, a method for producing a plastic optical fiber, wherein a core is produced integrally with the clad. 6. The method for producing a plastic optical fiber according to claim 5, wherein the ultraviolet curable resin composition is liquid at room temperature (23 ° C.). The method for producing a plastic optical fiber according to claim 5 or 6 , wherein the thickness of the tubular cladding is 0.25 to 2 mm. The method for producing a plastic optical fiber according to any one of claims 5 to 7 , wherein the clad material is a thermoplastic or thermosetting fluororesin.