JP4517580B2 - Transparent substrate on which cured film is formed and curable composition therefor - Google Patents

Description

【００１７】
式中、Ｒ¹は、水素、フッ素、アルキル基、フルオロアルキル基又はアリル基を表し、ｍは１〜４の整数を表し、Ｚは酸素又は硫黄を表し、Ｒ²はｍの値に応じて１〜４価の有機基を表し、ｎは１〜５の整数を表し、ｐは０〜２の整数を表し、Ｒ³は水素又は不活性な１価の有機基を表し、Ｒ⁴は加水分解可能な官能基を表す。
【００１８】
式（Ｉ）〜（III）において、Ｒ¹がアルキル基の場合、その炭素数は１〜６程度であることができ、具体的には、メチル、エチル、プロキル、ブチルなどが挙げられる。またフルオロアルキル基も、炭素数１〜６程度であることができる。
【００１９】
また、式（Ｉ）においてＲ²で表される有機基は、特に限定されないが、例えば、ｍが１の場合は、アルキル基などが、ｍが２の場合は、炭素数１〜１２の直鎖又は分枝状アルキレン基、直鎖又は分枝状のポリ（アルキレンオキシ）基などが、ｍが３又は４の場合は、類似の多価官能基が挙げられる。
【００２０】
式（III）においてＲ³で表される不活性な１価の有機基として、典型的には炭素数１〜４のアルキル基が挙げられ、またＲ⁴で表される加水分解可能な官能基としては、例えば、メトキシやエトキシなどを包含する炭素数１〜５のアルコキシ基、塩素原子や臭素原子のようなハロゲン原子などが挙げられる。
【００２１】
非芳香族エポキシ化合物としては、例えば、エチレングリコールジグリシジルエーテル、グリセリンジグリシジルエーテル、ビニルシクロヘキセンジオキサイド、１，２，８，９−ジエポキシリモネン、３，４−エポキシシクロヘキシルメチル ３′，４′−エポキシシクロヘキサンカルボキシレート、ビス（３，４−エポキシシクロヘキシル）アジペートなどが挙げられる。また、下記式（IV）で示される化合物も好適に使用される。
【００２２】
Ｒ⁵−(ＣＨ₂)_nＳｉ(Ｒ³)_p(Ｒ⁴)_3-p （IV）
【００２３】
式（IV）中、Ｒ⁵はエポキシ基含有の非芳香族基を表し、ｎ、ｐ、Ｒ³及びＲ⁴はそれぞれ前記式（III）におけるものと同様である。Ｒ⁵はその炭素数が２〜１０程度であることができ、その例としては、グリシジルオキシ基や３，４−エポキシシクロヘキシル基などが挙げられる。
【００２４】
これら非芳香族カチオン重合性化合物も、それぞれ単独で用いてもよいし、２種以上を併用してもよい。
【００２５】
非芳香族カチオン重合性化合物の中でも、前記式（III）や式（IV）で示されるような、分子内にシリル基を有する化合物又はその加水分解縮合物が好ましく用いられる。特に、前記式（III）の化合物をアルカリと水の存在下で加水分解縮合させることによって得られる、オキセタニル基を複数有するシルセスキオキサン化合物（ネットワーク状ポリシロキサン化合物）は、硬い被膜を与えるため、本発明に用いる材料として好適である。
【００２６】
また、後に述べるように硬化性組成物にシリカ微粒子を含有させる場合には、このシリカ微粒子との親和性も高いことから、上記のような分子内にシリル基を有する非芳香族カチオン重合性化合物、または、分子内にシリル基を有する非芳香族カチオン重合性化合物の加水分解縮合物が好適である。
【００２７】
分子内に芳香族環を含むと含まないとに関わらず、カチオン重合性化合物としては、オキセタン化合物とエポキシ化合物とを組み合わせて用いるのが好ましい。オキセタン化合物とエポキシ化合物とを組み合わせることで、オキセタン化合物の硬化がより促進され、より硬い被膜を得ることができる。この場合、エポキシ化合物は、オキセタン化合物１００重量部に対し、通常０．１〜９０重量部程度、好ましくは１〜７５重量部程度の割合で添加される。エポキシ化合物が０．１重量部に満たないと、反応速度が促進されずエポキシ化合物の添加効果が認められない可能性があり、９０重量部を超えると、膜の強度が低下する可能性がある。
【００２８】
芳香族カチオン重合性化合物と非芳香族カチオン重合性化合物の量比は、両者の合計量を１００重量部として、前者が５〜８０重量部、後者が２０〜９５重量部である。芳香族カチオン重合性化合物が５重量部に満たないと、基材との密着性が低下する可能性があり、一方、その量が８０重量部をこえると、膜の強度が低下する可能性がある。
【００２９】
本発明の硬化性組成物には、形成される硬化被膜の基材に対する密着性の観点から、シリカ微粒子を含有させるのが望ましい。このシリカ微粒子は特に限定されないが、平均粒径が５ｎｍ〜１０μｍの範囲にあるものが好ましく用いられる。特に反射防止膜として被膜を形成する場合には、平均粒径が５ｎｍ〜１００ｎｍの範囲にある微粒子がより好ましい。粒径があまり小さいシリカ微粒子は、工業的に製造することが困難であり、また粒径があまり大きくなると、被膜の透明性などの光学性能が低下するため、好ましくない。また、多孔質シリカ微粒子を用いてもよい。多孔質シリカは、屈折率が１．２〜１．４程度であり、通常のシリカ微粒子の屈折率１．４６に比べて屈折率が低く、反射防止材料を形成するうえで、より好ましい。多孔質シリカは、アルコキシシランをアルカリの存在下で加水分解することにより得られる、高度に絡み合って枝分かれし、ポリマー状に生成したシリカであってもよいし、特開平７−１３３１０５号公報に示される方法などで製造された、表面が被覆された多孔質シリカであってもよい。
【００３０】
シリカ微粒子の使用量は、カチオン重合性化合物１００重量部に対して、通常９００重量部以下、好ましくは５００重量部以下であり、また、通常１０重量部以上、好ましくは２０重量部以上である。シリカ微粒子の使用量があまり多いと、形成される硬化被膜の強度が低下することがある。また、シリカ微粒子の使用量があまり少ないと、その添加効果が発現され難く、特に多孔質シリカ微粒子を添加することで反射防止膜を形成する場合、その屈折率低減効果が得られ難い。反射防止膜を形成する場合には、被膜の屈折率が、好ましくは１.２０〜１.４５、より好ましくは１.２５〜１.４１になるように、シリカ微粒子の添加量を選択するのが好ましい。
【００３１】
また、本発明の組成物中には、表面の滑り性を改良するために、シリコーンオイルが添加されていてもよい。シリコーンオイルを添加することで、硬化被膜の滑り性が向上し、より耐擦傷性の高い硬い被膜とすることができる。
【００３２】
シリコーンオイルとしては、通常のものが使用でき、具体的には、ジメチルシリコーンオイル、フェニルメチルシリコーンオイル、アルキル・アラルキル変性シリコーオイル、フルオロシリコーンオイル、ポリエーテル変性シリコーンオイル、脂肪酸エステル変性シリコーンオイル、メチル水素シリコーンオイル、シラノール基含有シリコーンオイル、アルコキシ基含有シリコーンオイル、フェノール基含有シリコーンオイル、メタクリル変性シリコーンオイル、アミノ変性シリコーンオイル、カルボン酸変性シリコーンオイル、カルビノール変性シリコーンオイル、エポキシ変性シリコーンオイル、メルカプト変性シリコーンオイル、フッ素変性シリコーンオイル、ポリエーテル変性シリコーンオイルなどが例示される。これらシリコーンオイルは、それぞれ単独で用いてもよいし、２種以上を併用してもよい。
【００３３】
シリコーンオイルの添加量は、特に限定されないが、カチオン重合性化合物と必要に応じて用いられるシリカ微粒子との合計量１００重量部に対して、０．０１〜５０重量部が好ましい。０．０１重量部に満たないと、シリコーンオイルの添加効果が認められない可能性があり、５０重量部を超えると、膜の強度が低下する可能性がある。
【００３４】
本発明に用いる基材は、透明なものであれば特に限定されないが、例えば、ポリメチルメタクリレート樹脂、ポリカーボネート樹脂、ポリスチレン樹脂、メチルメタクリレート−スチレン共重合体樹脂、アクリロニトリル−スチレン共重合体樹脂、トリアセチルセルロース樹脂のような樹脂基材、また無機ガラスのような無機基材などが挙げられる。特に、メチルメタクリレート−スチレン共重合体は、吸湿による伸縮が小さく、反射防止板の基材として適しており、また、本発明の硬化性組成物による効果が発揮され易い。
【００３５】
基材は、板（シート）、フィルムなどのように、表面が平面のものであってもよいし、凸レンズや凹レンズなどのように、表面が曲率を有する基材であってもよい。また、表面に細かな凹凸が設けられていてもよい。基材が樹脂基材である場合には、その表面にハードコート層などの他の被膜が形成されていてもよい。
【００３６】
カチオン重合性化合物及び必要に応じてシリカ微粒子やシリコーンオイルなどを含有する本発明の硬化性組成物を、基材上に塗布するためには、これらの各成分を含む塗料として構成するのが望ましい。塗料には通常、上記各成分の他に、重合開始剤や溶剤、また必要により各種添加剤が含まれる。
【００３７】
重合開始剤は、硬化被膜を形成するために必要であり、本発明の硬化性組成物がカチオン重合性であることから、紫外線を照射することでカチオンを発生させる開始剤が好ましく用いられる。かかる開始剤としては、例えば、次の各式で示されるジアゾニウム塩、スルホニウム塩、ヨードニウム塩などのオニウム塩が好適に使用される。
【００３８】
ＡｒＮ₂ ⁺ Ｚ^-、
(Ｒ)₃Ｓ⁺ Ｚ^-、
(Ｒ)₂Ｉ⁺ Ｚ^-
【００３９】
式中、Ａｒはアリール基を表し、Ｒはアリール基又は炭素数１〜２０のアルキル基を表し、一分子内にＲが複数回現れる場合は、それぞれ同一でも異なっていてもよく、Ｚ^-は非塩基性でかつ非求核性の陰イオンを表す。
【００４０】
上記各式において、Ａｒ又はＲで表されるアリール基は、典型的にはフェニルやナフチルであり、これらは適当な基で置換されていてもよい。また、Ｚ^-で表される陰イオンとして具体的には、テトラフルオロボレートイオン（ＢＦ₄ ^-）、テトラキス（ペンタフルオロフェニル）ボレートイオン（Ｂ(Ｃ₆Ｆ₅)₄ ^-）、ヘキサフルオロホスフェートイオン（ＰＦ₆ ^-）、ヘキサフルオロアーセネートイオン（ＡｓＦ₆ ^-）、ヘキサフルオロアンチモネートイオン（ＳｂＦ₆ ^-）、ヘキサクロロアンチモネートイオン（ＳｂＣｌ₆ ^-）、硫酸水素イオン（ＨＳＯ₄ ^-）、過塩素酸イオン（ＣｌＯ₄ ^-）などが挙げられる。
【００４１】
これら各種の開始剤の多くは市販されているので、そのような市販品を用いることができる。市販の開始剤としては、例えば、ダウケミカル日本（株）から販売されている“ＣＹＲＡＣＵＲＥ ＵＶＩ−６９９０”、各々、旭電化工業（株）から販売されている“アデカオプトマー ＳＰ−１５０”及び“アデカオプトマー ＳＰ−１７０”、ローディアジャパン（株）から販売されている“ＲＨＯＤＯＲＳＩＬ ＰＨＯＴＯＩＮＩＴＩＡＴＯＲ ２０７４”などが挙げられる。
【００４２】
開始剤は、カチオン重合性化合物の合計量１００重量部に対し、通常０．１〜２０重量部程度、好ましくは０．５〜１０重量部程度の割合で添加される。開始剤の量があまり少ないと、カチオン重合性化合物の紫外線重合性が十分に発揮されず、またその量があまり多くなっても、増量効果が認められず、経済的に不利であるとともに、被膜の光学特性の低下をきたす可能性があるので、好ましくない。
【００４３】
溶剤は、塗料の濃度や粘度、硬化後の膜厚などを調整するために使用される。用いる溶剤は、適宜選択すればよいが、例えば、メタノール、エタノール、プロパノール、イソプロパノール、ｎ−ブタノール、２−ブタノール、イソブタノール、tert−ブタノールのようなアルコール類、２−エトキシエタノール、２−ブトキシエタノール、３−メトキシプロパノール、１−メトキシ−２−プロパノール、１−エトキシ−２−プロパノールのようなアルコキシアルコール類、ジアセトンアルコールのようなケトール類、アセトン、メチルエチルケトン、メチルイソブチルケトンのようなケトン類、トルエン、キシレンのような芳香族炭化水素類、酢酸エチル、酢酸ブチルのようなエステル類などが挙げられる。溶剤の使用量は、基材の材質、形状、塗布方法、目的とする被膜の膜厚などに応じて適宜選択されるが、通常は、カチオン重合性化合物と必要に応じて用いられるシリカ微粒子の合計量１００重量部当たり２０〜１０,０００重量部程度の範囲である。
【００４４】
また、塗料中には、安定化剤、酸化防止剤、着色剤、帯電防止剤などの添加剤が含有されていてもよい。
【００４５】
かかる塗料を基材の表面に塗布することにより、カチオン重合性化合物からなる被膜が形成される。基材の表面に塗料を塗布するには、通常と同様の方法、例えば、マイクログラビアコート法、ロールコート法、ディッピングコート法、フローコート法、スピンコート法、ダイコート法、キャスト転写法、スプレーコート法などの方法により塗布すればよい。
【００４６】
次いで、この被膜に紫外線を照射する。紫外線の照射時間は特に限定されないが、通常は０．１〜６０秒程度の範囲である。照射する紫外線の照射エネルギーは、通常５０〜３，０００ｍＪ／ｃｍ²程度である。紫外線の照射量があまり少ないと、硬化が不十分となり、膜の強度が低下する。また紫外線の照射量があまり多くなると、被膜や基材が劣化し、光学特性や機械物性の低下をきたす可能性があるので、好ましくない。
【００４７】
塗料が溶剤を含有する場合、紫外線は、被膜が溶剤を含有した状態のまま照射してもよいし、溶剤を揮発させた後に照射してもよい。溶剤を揮発させる場合には、室温で放置してもよいし、３０〜１００℃程度で加熱乾燥してもよい。乾燥時間は、基材の材質、形状、塗布方法、目的とする被膜の膜厚などに応じて適宜選択される。紫外線照射によって硬化被膜を形成した後、硬化被膜をより強固なものとするために、さらに加熱処理を施してもよい。加熱温度と時間は適宜選択されるが、通常５０〜１２０℃で５分〜２４時間程度である。
【００４８】
形成された硬化被膜は、膜厚が通常０．０１〜２０μｍであり、より好ましくは０．０１〜１０μｍである。膜厚が０．０１μｍに満たないと、硬化被膜としての特性を示しにくく、また２０μｍより大きいと、密着性が低下したり、ひび割れ等の不良が発生する可能性があるので、好ましくない。特に反射防止膜として被膜を形成させる場合には、膜厚を０．０１〜１μｍの範囲とするのが好ましい。膜厚が０．０１μｍに満たなくても１μｍを超えても、反射防止膜としての機能が低下しやすい。
【００４９】
【実施例】
以下、実施例により本発明をさらに詳細に説明するが、本発明はこれらの実施例によって限定されるものではない。例中、含有量ないし使用量を表す％及び部は、特記ないかぎり重量基準である。また、実施例で得た硬化被膜付き透明基材は、以下の方法で評価した。
【００５０】
（１）反射スペクトル
基材の測定面側とは反対側の面をスチールウールで粗面化し、黒色ペンキを塗って乾燥し、次いで測定面の入射角度５°における絶対鏡面反射スペクトルを紫外線可視分光光度計〔（株）島津製作所製の“ＵＶ−３１００”〕を用いて測定し、反射率の最小値を求めた。また反射率の最小値とそれを示す波長から、膜厚を算出した。
【００５１】
（２）密着性
基材の表面に、カッターナイフで硬化被膜を貫通するように、１ｍｍ角１００目の碁盤目状の切り込みを入れ、これにセロハンテープ〔ニチバン（株）製、２４ｍｍ幅〕を貼り、次いで垂直方向に剥がして、碁盤目１００個あたりの剥離数で評価した。
【００５２】
（３）耐擦傷性
消しゴム摩耗試験機〔（株）本光製作所製〕の消しゴム先端をガーゼで覆い、４９Ｎ／cm²の圧力を加えながら透明基材の表面を往復させて、目視で表面に傷が確認されるまでの往復回数で評価した。
【００５３】
実施例１〜５、比較例１
（ａ）硬化性組成物の調製
芳香族オキセタン化合物（１）として、３−エチル−３−（フェノキシメチル）オキセタン〔東亜合成（株）製の“アロンオキセタン ＯＸＴ−２１１”〕、芳香族オキセタン化合物（２）として、１，３−ビス（３−エチルオキセタン−３−イルメトキシ）ベンゼン〔東亜合成（株）製〕、非芳香族オキセタン化合物として、３−エチル−３−〔｛３−（トリエトキシシリル）プロポキシ｝メチル〕オキセタン〔式（III）において、Ｒ¹＝エチル、Ｒ³＝エトキシ、ｎ＝３、ｐ＝０の化合物〕の加水分解縮合物であるオキセタニルシルセスキオキサン〔東亞合成（株）製〕、非芳香族エポキシ化合物として、３，４−エポキシシクロヘキシルメチル ３′，４′−エポキシシクロヘキサンカルボキシレート〔ダウケミカル日本（株）から販売されている“ＣＹＲＡＣＵＲＥ ＵＶＲ−６１０５”〕、シリカ微粒子として、表面がエチルシリケートの加水分解重縮合物で被覆された粒径２０〜７０ｎｍの多孔質シリカ微粒子をイソプロピルアルコール中に２０％濃度で分散させたゾル、シリコーンオイルとして、メチルハイドロジェンシリコーンオイル〔信越化学製の“ＫＦ−９９”〕、溶剤として、イソプロピルアルコール及び２−ブトキシエタノール、光重合開始剤として、ｐ−クミル−ｐ−トリルヨードニウム テトラキス(ペンタフルオロフェニル)ボレート〔ローディアジャパン（株）から販売されている“ＲＨＯＤＯＳＩＬ ＰＨＯＴＯＩＮＩＴＩＡＴＯＲ ２０７４”〕を、それぞれ表１に示す組成比で混合し、塗料とした。
【００５４】
（ｂ）硬化被膜付き透明基材の作製
この塗料に、スチレン単位を約４０％含むメチルメタクリレート−スチレン共重合体樹脂板〔日本アクリエース（株）製の“アクリエースＭＳ”〕を浸漬し、表１に示した引上速度でディップ塗布して、室温で１分以上乾燥させた後、６０℃で１０分間乾燥させた。乾燥後、高圧水銀ランプ〔ウシオ電機（株）製の“ＵＶＣ−３５３３”〕により約１，０００ｍＪ／ｃｍ²のエネルギーで紫外線を照射して、反射防止性能を有する透明基材を得た。この透明基材の評価結果を表１に示した。
【００５５】
【表１】

【００５６】
【発明の効果】
本発明の硬化性組成物を用いれば、基材に対する密着性と硬度の点で優れる硬化被膜を形成することができる。この被膜が表面に形成された透明基材は、反射防止板として機能することもできるため、ディスプレイ、特にプロジェクションテレビなどの保護板として有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transparent substrate having a cured film formed on the surface, in particular, a transparent substrate having an antireflection film formed on the surface, and a curable composition suitable for forming the cured film. .
[0002]
[Prior art]
Conventionally, it is known to use a cationically polymerizable material as one method for forming a cured film on the surface of a transparent substrate such as glass or resin. For example, Japanese Patent Application Laid-Open No. 6-1557819 (Patent Document 1) proposes a composition for an optical material containing a cationically polymerizable compound and fine particles having an average particle size of 5 nm to 10 μm. It is described that those having a group or vinyl ether group can be used, and that the composition for optical materials can be used for coating glass or various plastics. Here, as the cationically polymerizable compound, in addition to an aliphatic epoxy compound and a vinyl ether compound, a silicone-based epoxy compound is disclosed.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 6-1557819
[Problems to be solved by the invention]
However, in the above conventional methods, the adhesion of the cured film to be formed to the substrate may be insufficient, or the hardness of the film may not be sufficient. Accordingly, an object of the present invention is to provide a transparent substrate having a sufficient adhesion to the substrate and having a cured film having a sufficient hardness. Another object of the present invention is to provide a curable material suitable for forming such a cured film.
[0005]
[Means for Solving the Problems]
As a result of intensive studies, the present inventor has found that the object can be achieved by using a specific composition as the curable material, and has completed the present invention.
[0006]
That is, the present invention comprises 5 to 80 parts by weight of a cationic polymerizable compound having an aromatic ring in the molecule and 20 to 95 parts by weight of a cationic polymerizable compound having no aromatic ring in the molecule. The transparent base material in which the cured film from the composition containing is formed is provided.
[0007]
Moreover, according to this invention, the sclerosing | hardenable containing 5-80 weight part of cationically polymerizable compounds which have an aromatic ring in a molecule | numerator, and 20-95 weight part of cationically polymerizable compounds which do not have an aromatic ring in a molecule | numerator. Compositions are also provided.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The curable composition of the present invention essentially contains a cationically polymerizable compound having an aromatic ring in the molecule and a cationically polymerizable compound having no aromatic ring in the molecule. In the present specification, the former may be called an aromatic cation polymerizable compound, the latter may be called a non-aromatic cation polymerizable compound, and both may be simply called a cation polymerizable compound. In the present invention, the total amount of these cationic polymerizable compounds is 100 parts by weight, the aromatic cationic polymerizable compound is used in a proportion of 5 to 80 parts by weight, and the non-aromatic cationic polymerizable compound is used in a proportion of 20 to 95 parts by weight. Moreover, the transparent base material of this invention is a thing in which the hardened film from this composition was formed in the surface of a base material, and this hardened film forms the surface functional layer or the antireflection layer.
[0009]
The aromatic cation polymerizable compound which is one of the essential components of the curable composition has at least one aromatic ring and at least one cation polymerizable functional group in the molecule. Examples of the polymerizable functional group include a vinyl ether group, an epoxy group, an oxetane ring, an aziridine ring, a lactone ring, and an oxazoline ring. Among these, those having an oxetane ring or an epoxy group, that is, an aromatic oxetane compound or an aromatic epoxy compound are preferable.
[0010]
Examples of aromatic oxetane compounds include 3-ethyl-3- (phenoxymethyl) oxetane, 1,4-bis (3-ethyloxetane-3-ylmethoxy) benzene, 1,3-bis (3-ethyloxetane-3 -Ylmethoxy) benzene, 4,4′-bis (3-ethyloxetane-3-ylmethoxy) biphenyl, and the like.
[0011]
As the aromatic epoxy compound, phenolic compounds such as bis (4-hydroxyphenyl) methane (bisphenol F), 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), phenol novolac, and cresol novolac The glycidylated product is representative.
[0012]
Examples of commercially available products of such aromatic cation polymerizable compounds include “Adekaoptomer KRM-2400” (bisphenol A cation polymerizable compound) and “Adeka optomer” sold by Asahi Denka Kogyo Co., Ltd. "KRM-2490" (bisphenol F-type cationic polymerizable compound), "Adekaoptomer KRM-2610" (phenol novolak-type cationic polymerizable compound), and "Adekaoptomer KRM-2650" (cresol novolak-type cationic polymerizable compound) And "Aron oxetane OXT-211" (3-ethyl-3- (phenoxymethyl) oxetane) sold by Toa Gosei Co., Ltd.
[0013]
These aromatic cation polymerizable compounds may be used alone or in combination of two or more.
[0014]
The non-aromatic cationically polymerizable compound which is another essential component of the curable composition has no aromatic ring in the molecule and has at least one cationically polymerizable functional group. Examples of the polymerizable functional group include those similar to the cationic polymerizable functional group in the aromatic cation polymerizable compound. Among these, those having an oxetane ring or an epoxy group, that is, a non-aromatic oxetane compound or a non-aromatic epoxy compound are preferable.
[0015]
Although various compounds can be used as the non-aromatic oxetane compound, preferred compounds include those represented by the following formulas (I) to (III).
[0016]
[Chemical 1]

[0017]
In the formula, R ¹ represents hydrogen, fluorine, an alkyl group, a fluoroalkyl group or an allyl group, m represents an integer of 1 to 4, Z represents oxygen or sulfur, and R ² represents a value of m. Represents a monovalent to tetravalent organic group, n represents an integer of 1 to 5, p represents an integer of 0 to 2, R ³ represents hydrogen or an inert monovalent organic group, and R ⁴ represents water Represents a functional group that can be decomposed.
[0018]
In the formulas (I) to (III), when R ¹ is an alkyl group, the carbon number thereof can be about 1 to 6, and specific examples include methyl, ethyl, prokyl, butyl and the like. The fluoroalkyl group can also have about 1 to 6 carbon atoms.
[0019]
Further, the organic group represented by R ² in the formula (I) is not particularly limited. For example, when m is 1, an alkyl group or the like is used, and when m is 2, a straight chain having 1 to 12 carbon atoms is used. When a chain or branched alkylene group, a linear or branched poly (alkyleneoxy) group, or the like is m or 3 or 4, a similar polyfunctional group is exemplified.
[0020]
The inactive monovalent organic group represented by R ³ in the formula (III) typically includes an alkyl group having 1 to 4 carbon atoms, and a hydrolyzable functional group represented by R ^4. Examples thereof include an alkoxy group having 1 to 5 carbon atoms including methoxy and ethoxy, and a halogen atom such as a chlorine atom and a bromine atom.
[0021]
Examples of the non-aromatic epoxy compound include ethylene glycol diglycidyl ether, glycerin diglycidyl ether, vinylcyclohexene dioxide, 1,2,8,9-diepoxy limonene, 3,4-epoxycyclohexyl methyl 3 ′, 4 ′. -Epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexyl) adipate and the like. In addition, a compound represented by the following formula (IV) is also preferably used.
[0022]
R ^5- (CH ₂ ) _n Si (R ³ ) _p (R ⁴ ) _3-p (IV)
[0023]
In the formula (IV), R ⁵ represents a non-aromatic group containing an epoxy group, and n, p, R ³ and R ⁴ are the same as those in the formula (III). R ⁵ may be the number of carbon atoms thereof is about 2 to 10, and examples thereof include such as glycidyl group or 3,4-epoxycyclohexyl group.
[0024]
These non-aromatic cationically polymerizable compounds may also be used alone or in combination of two or more.
[0025]
Among the non-aromatic cationically polymerizable compounds, compounds having a silyl group in the molecule or a hydrolysis condensate thereof as shown in the above formula (III) or formula (IV) are preferably used. In particular, the silsesquioxane compound (network polysiloxane compound) having a plurality of oxetanyl groups obtained by hydrolytic condensation of the compound of formula (III) in the presence of alkali and water gives a hard coating. It is suitable as a material used in the present invention.
[0026]
In addition, when silica fine particles are contained in the curable composition as described later, the non-aromatic cation polymerizable compound having a silyl group in the molecule as described above because of its high affinity with the silica fine particles. Alternatively, a hydrolytic condensate of a non-aromatic cation polymerizable compound having a silyl group in the molecule is preferable.
[0027]
Regardless of whether or not an aromatic ring is included in the molecule, it is preferable to use a combination of an oxetane compound and an epoxy compound as the cationic polymerizable compound. By combining the oxetane compound and the epoxy compound, curing of the oxetane compound is further promoted, and a harder film can be obtained. In this case, the epoxy compound is usually added at a ratio of about 0.1 to 90 parts by weight, preferably about 1 to 75 parts by weight with respect to 100 parts by weight of the oxetane compound. If the epoxy compound is less than 0.1 parts by weight, the reaction rate may not be accelerated and the addition effect of the epoxy compound may not be recognized. If it exceeds 90 parts by weight, the strength of the film may be reduced. .
[0028]
The amount ratio of the aromatic cation polymerizable compound and the non-aromatic cation polymerizable compound is 5 to 80 parts by weight for the former and 20 to 95 parts by weight for the latter, with the total amount of both being 100 parts by weight. If the amount of the aromatic cation polymerizable compound is less than 5 parts by weight, the adhesion to the substrate may be reduced. On the other hand, if the amount exceeds 80 parts by weight, the strength of the film may be reduced. is there.
[0029]
The curable composition of the present invention preferably contains silica fine particles from the viewpoint of adhesion of the formed cured film to the substrate. The silica fine particles are not particularly limited, but those having an average particle diameter in the range of 5 nm to 10 μm are preferably used. In particular, when a coating is formed as an antireflection film, fine particles having an average particle diameter in the range of 5 nm to 100 nm are more preferable. Silica fine particles having a very small particle size are difficult to produce industrially, and if the particle size is too large, optical performance such as transparency of the coating is lowered, which is not preferable. Further, porous silica fine particles may be used. Porous silica has a refractive index of about 1.2 to 1.4, which is lower than the refractive index of 1.46 of ordinary silica fine particles, and is more preferable for forming an antireflection material. The porous silica may be a silica that is obtained by hydrolyzing an alkoxysilane in the presence of an alkali and is highly intertwined and branched and formed into a polymer, as shown in JP-A-7-133105. The surface-coated porous silica produced by the method described above may be used.
[0030]
The amount of silica fine particles used is usually 900 parts by weight or less, preferably 500 parts by weight or less, and usually 10 parts by weight or more, preferably 20 parts by weight or more with respect to 100 parts by weight of the cationic polymerizable compound. If the amount of silica fine particles used is too large, the strength of the formed cured film may be reduced. In addition, when the amount of silica fine particles used is too small, the effect of addition is hardly exhibited, and particularly when the antireflection film is formed by adding porous silica fine particles, it is difficult to obtain the effect of reducing the refractive index. In the case of forming an antireflection film, the addition amount of silica fine particles is selected so that the refractive index of the film is preferably 1.20 to 1.45, more preferably 1.25 to 1.41. Is preferred.
[0031]
In addition, silicone oil may be added to the composition of the present invention in order to improve surface slipperiness. By adding silicone oil, the slidability of the cured film is improved, and a hard film having higher scratch resistance can be obtained.
[0032]
As the silicone oil, ordinary ones can be used. Specifically, dimethyl silicone oil, phenylmethyl silicone oil, alkyl / aralkyl-modified silicone oil, fluorosilicone oil, polyether-modified silicone oil, fatty acid ester-modified silicone oil, methyl Hydrogen silicone oil, silanol group-containing silicone oil, alkoxy group-containing silicone oil, phenol group-containing silicone oil, methacryl-modified silicone oil, amino-modified silicone oil, carboxylic acid-modified silicone oil, carbinol-modified silicone oil, epoxy-modified silicone oil, mercapto Examples thereof include modified silicone oil, fluorine-modified silicone oil, and polyether-modified silicone oil. These silicone oils may be used alone or in combination of two or more.
[0033]
The addition amount of the silicone oil is not particularly limited, but is preferably 0.01 to 50 parts by weight with respect to 100 parts by weight of the total amount of the cationic polymerizable compound and the silica fine particles used as necessary. If it is less than 0.01 part by weight, the effect of adding silicone oil may not be recognized, and if it exceeds 50 parts by weight, the strength of the film may be reduced.
[0034]
The substrate used in the present invention is not particularly limited as long as it is transparent. For example, polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, methyl methacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin, Examples thereof include a resin base material such as acetylcellulose resin, and an inorganic base material such as inorganic glass. In particular, methyl methacrylate-styrene copolymer is small in expansion and contraction due to moisture absorption, is suitable as a base material for an antireflection plate, and the effect of the curable composition of the present invention is easily exhibited.
[0035]
The substrate may have a flat surface such as a plate (sheet) or film, or a substrate having a curved surface such as a convex lens or a concave lens. Further, fine irregularities may be provided on the surface. When the substrate is a resin substrate, another film such as a hard coat layer may be formed on the surface thereof.
[0036]
In order to apply the curable composition of the present invention containing a cationically polymerizable compound and, if necessary, silica fine particles, silicone oil, etc. on a substrate, it is desirable to configure it as a paint containing these components. . The coating usually contains a polymerization initiator, a solvent and, if necessary, various additives in addition to the above components.
[0037]
The polymerization initiator is necessary for forming a cured film, and since the curable composition of the present invention is cationically polymerizable, an initiator that generates cations when irradiated with ultraviolet rays is preferably used. As such an initiator, for example, an onium salt such as a diazonium salt, a sulfonium salt, or an iodonium salt represented by the following formulas is preferably used.
[0038]
ArN ₂ ⁺ Z ⁻ ,
_{^{(R) 3 S + Z -}} ,
(R) ₂ I ⁺ Z ^-
[0039]
In the formula, Ar represents an aryl group, R represents an aryl group or an alkyl group having 1 to 20 carbon atoms, and when R appears multiple times in one molecule, they may be the same or different, and Z ⁻ is Represents a non-basic and non-nucleophilic anion.
[0040]
In each of the above formulas, the aryl group represented by Ar or R is typically phenyl or naphthyl, and these may be substituted with an appropriate group. Specific examples of the anion represented by Z ⁻ include tetrafluoroborate ion (BF ₄ ⁻ ), tetrakis (pentafluorophenyl) borate ion (B (C ₆ F ₅ ) ₄ ⁻ ), and hexafluorophosphate ion. (PF ₆ ⁻ ), hexafluoroarsenate ion (AsF ₆ ⁻ ), hexafluoroantimonate ion (SbF ₆ ⁻ ), hexachloroantimonate ion (SbCl ₆ ⁻ ), hydrogen sulfate ion (HSO ₄ ⁻ ), perchloric acid And ions (ClO ₄ ⁻ ).
[0041]
Since many of these various initiators are commercially available, such commercial products can be used. Examples of commercially available initiators include “CYRACURE UVI-6990” sold by Dow Chemical Japan Co., Ltd., “Adekaoptomer SP-150” and “ Adekaoptomer SP-170 "," RHODORSIL PHOTOINITIATOR 2074 "sold by Rhodia Japan Co., Ltd., and the like.
[0042]
The initiator is usually added at a ratio of about 0.1 to 20 parts by weight, preferably about 0.5 to 10 parts by weight, with respect to 100 parts by weight of the total amount of the cationic polymerizable compound. If the amount of the initiator is too small, the ultraviolet polymerizable property of the cationic polymerizable compound is not sufficiently exhibited, and even if the amount is too large, the effect of increasing the amount is not recognized, which is economically disadvantageous. This is not preferable because there is a possibility of deteriorating the optical characteristics.
[0043]
The solvent is used to adjust the concentration and viscosity of the paint, the film thickness after curing, and the like. The solvent to be used may be appropriately selected. For example, alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, isobutanol and tert-butanol, 2-ethoxyethanol, 2-butoxyethanol , Alkoxy alcohols such as 3-methoxypropanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ketols such as diacetone alcohol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, Examples thereof include aromatic hydrocarbons such as toluene and xylene, and esters such as ethyl acetate and butyl acetate. The amount of the solvent used is appropriately selected according to the material of the substrate, the shape, the coating method, the film thickness of the target film, etc. Usually, the cationic polymerizable compound and the silica fine particles used as necessary are used. The total amount is in the range of about 20 to 10,000 parts by weight per 100 parts by weight.
[0044]
The paint may contain additives such as a stabilizer, an antioxidant, a colorant, and an antistatic agent.
[0045]
By coating such a paint on the surface of the substrate, a film made of a cationic polymerizable compound is formed. In order to apply the paint to the surface of the substrate, the same method as usual, for example, micro gravure coating method, roll coating method, dipping coating method, flow coating method, spin coating method, die coating method, cast transfer method, spray coating What is necessary is just to apply | coat by methods, such as a method.
[0046]
Next, the coating film is irradiated with ultraviolet rays. Although the ultraviolet irradiation time is not particularly limited, it is usually in the range of about 0.1 to 60 seconds. The irradiation energy of ultraviolet rays to be irradiated is usually about 50 to 3,000 mJ / cm ² . When the irradiation amount of ultraviolet rays is too small, the curing becomes insufficient and the strength of the film is lowered. On the other hand, if the amount of irradiation with ultraviolet rays is too large, the coating film and the base material are deteriorated, and there is a possibility that optical characteristics and mechanical properties are lowered, which is not preferable.
[0047]
When the coating material contains a solvent, the ultraviolet light may be irradiated while the film contains the solvent, or may be irradiated after the solvent is volatilized. When the solvent is volatilized, it may be left at room temperature or may be dried by heating at about 30 to 100 ° C. The drying time is appropriately selected according to the material, shape, coating method, target film thickness, and the like of the substrate. After the cured film is formed by irradiation with ultraviolet rays, heat treatment may be further performed to make the cured film stronger. The heating temperature and time are appropriately selected, but are usually about 50 to 120 ° C. and about 5 minutes to 24 hours.
[0048]
The formed cured film has a film thickness of usually 0.01 to 20 μm, more preferably 0.01 to 10 μm. If the film thickness is less than 0.01 μm, it is difficult to show the properties as a cured film, and if it is larger than 20 μm, the adhesion may be lowered or defects such as cracks may occur, which is not preferable. In particular, when a film is formed as an antireflection film, the film thickness is preferably in the range of 0.01 to 1 μm. Even if the film thickness is less than 0.01 μm or exceeds 1 μm, the function as an antireflection film tends to be lowered.
[0049]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. Moreover, the transparent base material with a cured film obtained in the Example was evaluated with the following method.
[0050]
(1) Reflection spectrum The surface opposite to the measurement surface side of the base material is roughened with steel wool, dried by applying black paint, and then the absolute specular reflection spectrum at an incident angle of 5 ° on the measurement surface is UV-visible spectroscopy. Measurement was performed using a photometer [“UV-3100” manufactured by Shimadzu Corporation] to obtain the minimum value of reflectance. The film thickness was calculated from the minimum reflectance and the wavelength indicating the reflectance.
[0051]
(2) On the surface of the adhesive base material, a grid-like cut of 1 mm square 100 mm is made so as to penetrate the cured film with a cutter knife, and cellophane tape [made by Nichiban Co., Ltd., 24 mm width] is put into this. The film was attached and then peeled off in the vertical direction, and the number of peels per 100 grids was evaluated.
[0052]
(3) Cover the tip of the eraser of the scratch-resistant eraser wear tester (manufactured by Honko Seisakusho Co., Ltd.) with gauze, reciprocate the surface of the transparent substrate while applying a pressure of 49 N / cm ² , and visually check the surface. Evaluation was based on the number of round trips until the scratch was confirmed.
[0053]
Examples 1-5, Comparative Example 1
(A) Preparation of curable composition As aromatic oxetane compound (1), 3-ethyl-3- (phenoxymethyl) oxetane ["Aron oxetane OXT-211" manufactured by Toagosei Co., Ltd.], aromatic oxetane compound As (2), 1,3-bis (3-ethyloxetane-3-ylmethoxy) benzene [manufactured by Toa Gosei Co., Ltd.], and as a non-aromatic oxetane compound, 3-ethyl-3-[{3- (triethoxy Silyl) propoxy} methyl] oxetane [compound of formula (III) wherein R ¹ = ethyl, R ³ = ethoxy, n = 3, p = 0] oxetanylsilsesquioxane [Toagosei Co., Ltd.], 3,4-epoxycyclohexylmethyl 3 ', 4'-epoxycyclohexanecarboxylate [Dauke] “CYRACURE UVR-6105” sold by Cal Japan Co., Ltd.] As silica fine particles, porous silica fine particles with a particle size of 20-70 nm coated with a hydrolyzed polycondensate of ethyl silicate in isopropyl alcohol Sol dispersed at a concentration of 20%, silicone oil as methyl hydrogen silicone oil (“KF-99” manufactured by Shin-Etsu Chemical), isopropyl alcohol and 2-butoxyethanol as solvents, p- Cumyl-p-tolyliodonium tetrakis (pentafluorophenyl) borate [“RHODOSIL PHOTOINITITOR 2074” sold by Rhodia Japan Co., Ltd.] was mixed at the composition ratio shown in Table 1 to obtain a paint.
[0054]
(B) Production of transparent substrate with cured coating In this paint, a methyl methacrylate-styrene copolymer resin plate (“Acryase MS” manufactured by Nippon Acryase Co., Ltd.) containing about 40% of styrene units was immersed. The film was dip-coated at the pulling speed shown in Fig. 1 and dried at room temperature for 1 minute or more, and then dried at 60 ° C for 10 minutes. After drying, a high-pressure mercury lamp (“UVC-3533” manufactured by USHIO INC.) Was irradiated with ultraviolet rays at an energy of about 1,000 mJ / cm ² to obtain a transparent substrate having antireflection performance. The evaluation results of this transparent substrate are shown in Table 1.
[0055]
[Table 1]

[0056]
【The invention's effect】
If the curable composition of this invention is used, the cured film excellent in the point of the adhesiveness with respect to a base material and hardness can be formed. Since the transparent base material on which the coating film is formed can function as an antireflection plate, it is useful as a protective plate for displays, particularly projection televisions.

Claims (6)

5 to 80 parts by weight of a cationic polymerizable compound having an aromatic ring in the molecule on the substrate surface, 20 to 95 parts by weight of a cationic polymerizable compound having no aromatic ring in the molecule, and an aromatic in the molecule Cured coating by ultraviolet irradiation from a composition comprising 900 parts by weight or less of silica fine particles with respect to a total of 100 parts by weight of a cationically polymerizable compound having a ring and a cationically polymerizable compound having no aromatic ring in the molecule A transparent substrate characterized in that is formed.   2. The transparent substrate according to claim 1, wherein the cationically polymerizable compound having no aromatic ring in the molecule is a compound having a silyl group in the molecule or a hydrolysis condensate thereof. Transparent substrate according to claim 1 or 2 silica particles are porous silica particles. The transparent substrate according to any one of claims 1 to 3 , wherein the cured film is a film having a refractive index of 1.20 to 1.45 and a film thickness of 0.01 to 1 µm and having an antireflection function. The transparent substrate according to any one of claims 1 to 4 , wherein the substrate is a methyl methacrylate-styrene copolymer resin. An antireflection plate comprising the transparent substrate according to any one of claims 1 to 5.