JP3861380B2 - OPTICAL THIN FILM CONTAINING FLUORINE-CONTAINING COMPOUND AND METHOD FOR FORMING THE SAME - Google Patents

Description

前記光学薄膜の厚さは、３０〜７００ｎｍが実用上好適である。また、光学薄膜に 用いる一般式（１）の化合物では、ｎが４〜１２のうちのいずれかの整数の化合物が 好ましい。さらに、一般式（１）の化合物中、Ａ1，Ａ2，Ａ3，Ａ4 のいずれかにア クリロイル基を有する化合物が好適である。また、光学薄膜としては、一般式（１） の化合物１００重量部に対し、０〜２０重量部の多官能（メタ）アクリレートを含有 させ、および／または一般式（１）の化合物１００重量部に対し、０〜１００重量部 の単官能（メタ）アクリレートを含有させることができる。本発明の光学薄膜は、光 によって硬化させるとよい。前記の光学薄膜は、一般式（１）の化合物を含有する組 成物の溶剤を調整し、基材の表面に塗布し、光を照射して硬化して形成することがで きる。
【００１０】
また、本発明は、前記のいずれかの光学薄膜を基材表面に形成してなる光反射防止性物品を提供する。本発明の光反射防止性物品においては、基材の表面と光学薄膜との中間に、有機および／または無機系バインダーと金属化合物の微粒子とからなり、かつ屈折率が基材の屈折率の±０．０２以内のハードコート層を形成してもよく、さらに、ハードコート層と光学薄膜との中間に、光学薄膜およびハードコート層の屈折率よりも高い屈折率を有する高屈折率膜を重ねて形成させることもできる。
【００１１】
【発明の実施の形態】
本発明を具体的な実施形態例をあげながら、順次説明する。
まず、前記の一般式（１）で示される含フッ素化合物の製造方法を説明する。一般式（１）の含フッ素化合物のｄが０の場合は、化３に一般式（２）で示される（メタ）アクリル酸、または一般式（３）で示される（メタ）アクリル酸クロライドと、化４に一般式（４）で示される含フッ素化合物とをエステル化反応させて製造することができる。なお、一般式（４）の含フッ素化合物は、一般式（５）で示される化合物を加水分解して合成することができる。
【００１２】
【化３】

【００１３】
【化４】

【００１４】
【化５】

また、一般式（１）に示される化合物のｄが１の場合は、前記一般式（４）で示される含フッ素化合物と、化６に一般式（６）で示されるイソシアネート化合物とをウレタン化反応させることにより合成することができる。
【００１５】
【化６】

一般式（６）のｃが１のイソシアネート化合物ではｂが２の化合物を製造しやすいので、好ましく利用することができる。ウレタン化反応による合成は、容易で副反応生成物が少なく一般的に利用しやすい。とくに、光学薄膜として利用する場合には、光学薄膜を形成するための塗料を調整する工程で反応させることのできる、ウレタン化反応を好ましく使用できる。
【００１６】
次に、一般式（１）に示される化合物は、式中のＡ1，Ａ2，Ａ3，Ａ4のうちの少な くとも１つに、−Ｈ以外の一般式（ａ）で示される有機基、かつウレタン残基を導入 しておくことにより、ラジカル付加重合により硬化することができる。そして、重合 して得られる硬化物質は屈折率が低く、通常は１．４５を超えないという特性を有す ることが見出だされた。さらに、Ａ1，Ａ2，Ａ3，Ａ4 のうちの少なくとも２つに、 −Ｈ以外の前記有機基を導入しておくことにより、重合して得られる硬化物質が高い 硬化性能を有することも判明し、たとえば、低屈折率の光学薄膜に好適であることが 判った。この他、各種の表示、展示部材、透明部材、光学機器の構成素材への利用が 期待される。
【００１７】
さて、以下に、一般式（１）の化合物を本発明の低屈折率光学薄膜として利用する場合について説明する。一般式（１）の化合物は、ラジカル熱重合、光重合、電子線重合などにより重合し、硬化することができる。光学薄膜に利用する場合には、重合（硬化）速度が速いことと設備の簡便性とから、紫外線を用いる光重合（硬化）が好適である。光重合においては、一般的にメタクリロイル基よりもアクリロイル基である方が進み易く、従って光学薄膜を形成するには、Ａ１，Ａ２，Ａ３，Ａ４のいずれかがアクリロイル基を持つ化合物が好適である。なかでもアクリロイル基を２つ以上有する化合物が好ましい。
【００１８】
一般式（１）の化合物を光学薄膜に利用するには、硬化物の屈折率ができるだけ低いことが望ましく、ｎが２〜１４の整数である化合物を好ましく利用できる。ｎが２未満では屈折率が十分に低くなりにくく、１４より大きくなると光学薄膜の硬度が十分に高くなりにくい傾向が見られる。ｎは４〜１２の整数であればさらに好適である。
【００１９】
本発明の光学薄膜では一般式（１）で示される含フッ素化合物を少なくとも４５重量％含むことが必要であるが、前記含フッ素化合物のほかに、硬度、上下層との密着性、屈折率の調整やその他の性能を向上する目的で、他の多官能モノマを添加することができる。添加量は、前記の含フッ素化合物１００重量部に対し、２０重量部以下、望ましくは１５重量部以下である。多官能モノマを２０重量部以上添加すると、屈折率が１．４５を超える場合があり、所望の反射防止性能を得ることが難しくなる傾向がある。
【００２０】
添加する多官能モノマとしては、エチレングリコールジ（メタ）アクリレート、ジエチレングリコールジ（メタ）アクリレート、ネオペンチルグリコールジ（メタ）アクリレート、１，６−ヘキサンジオールジ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、ペンタエリスリトールトリ（メタ）アクリレート、ペンタエリスリトールテトラ（メタ）アクリレート、ジペンタエリスリトールヘキサ（メタ）アクリレート、ジペンタエリスリトールペンタ（メタ）アクリレート、ジペンタエリスリトールテトラ（メタ）アクリレート、ジトリメチロールプロパントリ（メタ）アクリレート、１，１，１−トリス［（メタ）アクリロイルオキシエトキシエトキシ］プロパン、トリス（ヒドロキシエチル）イソシアヌレートトリ（メタ）アクリレート、トリス（ヒドロキシエチル）イソシアヌレートジ（メタ）アクリレートなどがあげられる。これらの多官能モノマは単独または２種以上を混合して添加することができる。本発明の光学薄膜に好ましい添加多官能モノマとして、硬度を向上する効果の高い３官能以上の（メタ）アクリレート類があげられる。
【００２１】
上記の他に、不飽和二重結合を一個有する含フッ素またはフッ素を含まない単官能モノマを一般式（１）の含フッ素化合物１００重量部に対し、１００重量部以下、望ましくは９０重量部を超えない量および重合開始剤を添加することができる。単官能モノマが１００重量部を越えると、光学薄膜の硬度が低くなる傾向がある。不飽和二重結合を一個有する含フッ素単官能モノマとして、２，２，２−トリフルオロエチル（メタ）アクリレート、２，２，３，３−テトラフルオロプロピル（メタ）アクリレート、２，２，３，４，４，４−ヘキサフルオロブチル（メタ）アクリレート、１Ｈ，１Ｈ，２Ｈ，２Ｈ−パーフルオロデカノール（メタ）アクリレート、β−（パーフルオロオクチル）エチル（メタ）アクリレートなどがあげられる。これらのモノマや化合物は、適宜、硬度、屈折率の調整、コーティング性の調整などのために加えられ、硬化して光学薄膜とすることができる。光学薄膜の屈折率を下げるためには、不飽和二重結合を１つ含むフッ素含有量の多い化合物を添加するのが好ましい。
【００２２】
さらに、フッ素を含まない単官能モノマとしては、メチル（メタ）アクリレート、２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシプロピル（メタ）アクリレート、２−ヒドロキシ−３−フェノキシプロピル（メタ）アクリレートなどがあげられるが、相溶性がよく、屈折率が１．４５を超えない硬化膜が得られるのであれば特別な制限はない。
【００２３】
さらにコーティング性を向上するためにレベリング剤やシラン系カップリング剤を添加してもよい。添加量は、好ましくは硬化物全体の０．０５〜５重量％、より好ましくは０．１〜２重量％である。
【００２４】
本発明の光学薄膜の形成方法を実施形態例をあげて説明する。本発明の光学薄膜は、低屈折率であるところから主に基材の反射防止に利用される。本発明光学薄膜は、一般式（１）で示される含フッ素化合物化合物を単体、または必要により多官能モノマ、重合開始剤、単官能モノマ、レベリング剤などを添加した組成物とし、そのまま、もしくは適当な溶剤で希釈し、塗剤にして基材表面に塗布してから、重合、硬化して形成するとよい。
【００２５】
溶剤としては、プロパノール、イソプロパノール、ブタノールなどのアルコール系；メチルイソブチルケトン、メチルエチルケトンなどのケトン系；酢酸エチルなどのエステル系；ハロゲン系；テトラヒドロフランなどがあげられる。
【００２６】
塗布手段は、基材に均一に塗布できる方法であれば特に制限はなく、スピンコート、ディップコート、ダイコート、スプレーコート、バーコーターコート、ロールコート、カーテンフローコートなどの塗布方法を利用することができる。
【００２７】
前記の塗剤は、所要の厚さに均一に基材に塗布した後、硬化される。本発明の光学薄膜を形成できる基材にとくに制限はないが、ガラス、ポリカーボネートやアクリル樹脂などの樹脂成形物、ポリエチレンテレフタレートフィルムなどのフィルム類などの光反射防止に効果的に利用することができる。ほかにも撥水、撥油性能などの優れた特性を具備するので、それらを利用する薄膜を形成してもよい。基材の形状に制限はない。
【００２８】
重合、硬化には、熱重合法、電子線重合法、光重合法（紫外線重合法）などを利用するとよい。なかでも、基材の耐熱性によって制限されない光重合法が好ましい。光重合法を利用する場合には、通常、あらかじめ塗剤に光重合開始剤を添加しておくとよい。光重合開始剤として、２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン、１−ヒドロキシシクロヘキシルフェニルケトン、２−メチル−１−［４−（メチルチオ）フェニル］−２−モルホリノプロパノン−１などを利用できる。光重合開始剤の添加量は、硬化物組成全体の０．１〜２０重量％、好ましくは０．１〜１０重量％である。光源には低圧または高圧水銀灯、キセノン灯などを用い、塗布基材に紫外線を照射して塗膜を重合、硬化する。
【００２９】
本発明の光学薄膜は基材に単層としてのみではなく、他の薄膜と積層して形成することもできる。たとえば、密着性や塗布性を向上させるために基材を表面処理したり、基材の硬度を向上させるためにハードコート層を積層して光反射防止性物品にすることができる。さらに、基材の反射防止効果を高めるために、高屈折率の光学薄膜を基材と本発明の光学薄膜との中間に形成することもできる。本発明の光学薄膜と高屈折率薄膜とを交互に積層することにより、より優れた反射防止膜を得ることもできる。高屈折率膜は、基材と同等もしくはそれ以上の屈折率が必要であり、具体的には少なくとも１．５８が好ましく、さらに好ましくは、１．６以上、より好ましくは、１．７以上である。
【００３０】
本発明の光学薄膜を他の薄膜と積層して形成した光反射防止性物品の好ましい実施態様例を説明する。基材のポリカーボネートやメタクリル樹脂などの表面に、硬度付与と干渉縞発生を防止するために基材との屈折率差が±０．０２以内，厚さ２〜５μｍ程度のハードコート層を設ける。ハードコート層は、有機系または無機系のバインダーに、必要によりＳｉ，Ｓｂ，Ｃｅ，Ｔｉ，Ｓｎなどの金属酸化物微粒子、すなわち一般的には可視光線の波長よりも小さい粒子径の微粒子を添加した塗膜を用いる。有機バインダーとしては、エポキシ樹脂硬化物やラジカル架橋重合した樹脂などが、無機系バインダーとしては、シラン系化合物の加水分解硬化物などがあるが、特に制限はない。硬化には一般的に熱硬化法よりも光硬化法を用いる方が硬化速度が速く好ましい。
【００３１】
高い反射防止性を得るために、ハードコート層の表面に前記の高屈折率薄膜を積層することができる。高屈折率膜の厚さは９０〜４００ｎｍ、より好ましくは１１０〜１８０ｎｍに形成する。高屈折率膜は、一般に金属酸化物の真空蒸着膜であるが、Ｓｂ，Ｃｅ，Ｔｉ，Ｓｎなどの金属酸化物を含み、（メタ）アクリレート類，シラン類，エポキシ樹脂類などをバインダーとして硬化された層である。金属酸化物に導電性がある場合は滞電防止性を付与できて好ましい。また、バインダーを光硬化法で硬化できれば硬化速度が速く好ましい。
【００３２】
基材上に透明な低屈折率膜を一層設けると、入射反射光の一部は空気と薄膜との境界で反射し、一部は薄膜と基材界面で反射し、全体として反射光はそれらの干渉光となって、結果的に基材の反射率を低減もしくは増加させる。低屈折率膜は、光が干渉作用をおこす程度に薄く、光反射防止性物品の光反射率は低屈折率膜の屈折率と膜厚に依存する。
【００３３】
低屈折率膜の厚さはλ／４ｎ（λ：薄膜内での光の波長、ｎ：薄膜の屈折率）の奇数倍が好ましい。光の波長に幅のある場合、λは光の中心波長を基準にする。本発明で中心波長は、５００〜５５０ｎｍに設定するのが好ましい。低屈折率膜の厚さは、膜の屈折率にもよるが具体的に３０〜７００ｎｍが好ましく、より好ましくは、４０〜１２０ｎｍの範囲である。低屈折率膜の厚さが３０ｎｍ未満の場合は、可視光における光干渉作用による反射率の低減が不十分になることがある。また、膜厚が７００ｎｍを超えると、反射率がほぼ空気と薄膜界面の反射のみに依存するようになるので、可視光の光干渉による反射率の低減が不十分になる傾向がある。例えば、屈折率１．６の基材に屈折率１．３８の薄膜を形成した場合、膜の厚さが適当であれば反射率は１％以下になるが、数μｍを超えると反射率は約３％になる。低屈折率薄膜の屈折率が１．４５以上であると比較的屈折率の低いポリメチルメタクリレートやガラスなどを基材とする物品の反射防止効果が顕著でなくなる。
【００３４】
【実施例】
本発明を実施例をあげてさらに具体的に説明する。なお、以下の実施例および参考例において用いた評価手段および測定手段は次の通りである。
ａ．膜の厚さ：エリプソメータによる測定値。
ｂ．片面反射率：測定面の裏面をサンドペーパで粗面化した後、油性インキで黒塗りし、分光光度計を用い、５４０ｎｍにおける測定面の反射率を測定した。
【００３５】
ｃ．干渉縞：蛍光灯スタンドの２０ｃｍ下にサンプルを静置し、肉眼観察により評価した。
ｄ．耐擦傷性：消しゴム（Ｎｏ．５０（ライオン（株）製）を接触面積約０．５ｃｍ² 、荷重１ｋｇで反射面上を２０回往復させた後、肉眼判定し、擦過痕が認められないものを合格判定した。
【００３６】
【００３７】
【００３８】
【００３９】
実施例１
表１に記載の組成の反応液（Ｃ−Ｌ1 ）を調合し、４５℃で８時間反応させて 、ウレタン結合を持つ含フッ素化合物を合成した。得られた反応液５０２重量部に表 １に記載の組成の反応液（Ｃ−Ｌ2 ）を加え、塗料Ｃを調整した。調整した塗料Ｃ を厚さ２ｍｍのポリカーボネート板の表面にスピンコートし、８０℃のオーブンで１ ０分間、加熱した。高圧水銀灯で５，０００ｍＪ／ｃｍ 2 照射して、厚さ９５ｎｍ の硬化膜（本発明の光学薄膜）を形成した。形成した光学薄膜の屈折率はｎｄ＝１． ４１、片面反射率は１．２％であった。
【００４０】
【表１】

実施例２
表２に記載の組成の塗料Ｄを調整した。調整した塗料Ｃを用い、実施例１と同 様にしてポリカーボネート板の表面に光学薄膜を形成した。形成した光学薄膜の 屈折率はｎｄ＝１．４０、片面反射率は１．１％であった。
【００４１】
【表２】

実施例３、４
厚さが２ｍｍ、屈折率ｎｄが１．５９のポリカーボネート板に、五酸化アンチモン 超微粒子（平均粒径（ＢＥＴ法）２０ｎｍ）、ペンタエリスリトールトリアクリレー トおよび２−ヒドロキシ−３−フェノキシアクリレートを主成分とする、屈折率１． ５９、厚さ３μｍのハードコート層を、光硬化により形成した。形成したハードコー ト層の表面に、実施例１、２において調整した塗料Ｃ，Ｄを実施例１、２と同様に塗 布し、硬化せしめて本発明の光学薄膜を形成した。形成した光学薄膜の評価結果を表 ３に示す。いずれの光学薄膜も高い耐擦傷性を示した。
【００４２】
【表３】

実施例５、６
実施例３、４と同様にして、厚さが２ｍｍ、屈折率ｎｄが１．５９のポリカーボネ ート板にハードコート層を形成した。形成したハードコート層の表面に、アンチモン ドープ酸化スズ超微粒子（平均粒径（ＢＥＴ法）４０ｎｍ）、ペンタエリスリトール トリアクリレート，２−ヒドロキシ−３−フェノキシアクリレートを主成分とする、 厚さ１５０ｎｍ，屈折率ｎｄ＝１．７０，表面抵抗値２×１０9 Ω／□の導電性高 屈折率層を光硬化により積層した。さらに、実施例１、２と同様に塗料Ｃ，Ｄを塗布 、硬化せしめて本発明の光学薄膜を形成した。形成した光学薄膜の評価結果を表４に 示す。いずれの光学薄膜も高い耐擦傷性を示した。
【００４３】
【表４】

実施例７
屈折率ｎｄ＝１．５３、厚さ２ｍｍのガラス板に、真空蒸着法により厚さ１４５ｎ ｍのＩＴＯ膜（Ｉｎ2 Ｏ3 系の透明高導電性薄膜）を形成した。実施例２で調整した 塗料Ｄを、前記のＩＴＯ膜の表面に実施例１と同様に塗布し、硬化せしめて本発明の 光学薄膜を形成した。形成した光学薄膜の片面反射率は０．６％であった。
【００４４】
【発明の効果】
本発明が提供する含フッ素化合物の硬化物は極めて低屈折率であって、硬化後の硬度が大きく、とくに低屈折率光学薄膜として有望である。かつ、表面硬度が大で耐擦傷性、耐久性に優れている。他にも、はっ水性や耐油性にも高い効果を奏する。しかも、硬化前は溶剤に可溶なため、簡便かつ連続処理が可能で経済的な溶液コーティングにより塗布し、硬化することができる。また、ハードコート層や高屈折率膜に重ねて本発明の光学薄膜を形成し、耐擦傷性、光反射防止性能をさらに向上させ、多機能性を付与することができる。光学薄膜以外にもこの他、各種の表示、展示部材、透明部材、光学機器の構成素材への利用が期待される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical thin film having a low refractive index excellent in scratch resistance containing a fluorine-containing compound, a method for forming the same, and an antireflective article using the optical thin film. The optical thin film of the present invention can be formed on the surface of an article such as a cathode ray tube, a liquid crystal display device, an antireflection filter for CRT, an antireflection filter for plasma display, glass or a lens, and used for antireflection of light rays.
[0002]
In the present invention, an optical thin film refers to a thin film that forms a transparent thin film on the surface of the base material and causes interference by crossing at a boundary having a different refractive index when a light beam irradiating the base material enters the base material. Say. The thickness of the optical thin film is usually 1 μm or less. Further, the refractive index is a value at the D-line of the sodium emission spectrum unless otherwise specified. Further, the single-sided reflectance (also simply referred to as reflectance) is a measured value for light having a wavelength of 540 nm.
[0003]
[Prior art]
Many of the conventional light antireflective articles prevent reflection of light by alternately laminating a single layer low refractive index optical thin film or a low refractive index and high refractive index optical thin film on the surface. The reflected light of the optical thin film is interference light of each reflected light on the optical thin film surface and the thin film boundary surface, and the reflectance is reduced or increased depending on the refractive index and the film thickness of the optical thin film, but the refractive index is low in principle. The lower the reflectivity, the more advantageous. The optical thin film generally forms an inorganic coating on the surface of an article (base material) using vapor deposition or sputtering. The obtained antireflection film has low reflectivity and excellent scratch resistance. However, since a vacuum apparatus or the like is used, the productivity is poor and the manufacturing cost is high. In addition, since the substrate is heated in the manufacturing process, there is a problem that the usable materials are limited.
[0004]
In order to solve the above problem, Japanese Patent Laid-Open No. 4-355401 and Japanese Patent Laid-Open No. 6-18705 disclose low refractive index reflection by dissolving a low refractive index organic substance in a solvent and coating the substrate. A solution coating method for forming a protective film is disclosed. If the solution coating method is used, it is possible to coat a fluorine-containing resin having a refractive index lower than that of the magnesium fluoride thin film having the lowest refractive index among the inorganic thin films. Moreover, solution coating is highly productive and economical.
[0005]
However, the organic thin film made of the fluorine-containing resin described in JP-A-4-355401 and JP-A-6-18705 has a low surface hardness because of the low crosslink density of the fluorine-containing resin cured product, and there is a problem in scratch resistance. was there. Furthermore, after coating, the substrate that can be used is limited because it requires heat curing. In addition, U.S. Pat. No. 3,310,606 discloses a cured product of perfluorodivinyl ether as a fluorine-containing resin having a high crosslinking density and a high surface hardness. An optical thin film cannot be obtained because it needs to be molded below.
[0006]
JP-A-8-239430 discloses water / oil repellency and scratch resistance containing 10 to 90 parts by weight of polyfunctional (meth) acrylate with respect to 100 parts by weight of fluorine-containing di (meth) acrylate having a specific structure. A fluorine-containing curable composition having the properties is disclosed. However, this curable composition tends to have a refractive index exceeding 1.45, and it is difficult to obtain antireflection properties.
[0007]
[Problems to be solved by the invention]
The present invention relates to a compound capable of forming a low-reflective thin film, an optical thin film that has low reflectivity, has excellent scratch resistance and durability after curing, and can be easily formed. As a result of research, the present invention has been completed with the object of providing an antireflection article having the optical thin film formed on the surface thereof.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present inventors have synthesized various compounds including a novel synthetic product, measured optical characteristics, mechanical characteristics, and the like, and examined the applicability to the optical thin film. As a result, it has been found that the fluorine-containing compound represented by the general formula (1) of Chemical Formula 2 has a low refractive index, a large hardness after curing, and is extremely promising as an optical thin film. That is, this invention provides the optical thin film characterized by hardening the composition containing the compound shown by General formula (1), and a refractive index being 1.45 or less.
[0009]
[Chemical 2]

The thickness of the optical thin film is preferably 30 to 700 nm. In addition, in the compound of the general formula (1) used for the optical thin film, a compound in which n is an integer from 4 to 12 is preferable. Further, among the compounds of the general formula (1), a compound having an acryloyl group at any of A1, A2, A3 and A4 is preferable . The optical thin film contains 0 to 20 parts by weight of polyfunctional (meth) acrylate and / or 100 parts by weight of the compound of general formula (1) with respect to 100 parts by weight of the compound of general formula (1). On the other hand, 0 to 100 parts by weight of monofunctional (meth) acrylate can be contained. The optical thin film of the present invention is preferably cured by light. The optical thin film can be formed by adjusting the solvent of the composition containing the compound of the general formula (1), applying it to the surface of the substrate, and irradiating with light to cure.
[0010]
The present invention also provides an anti-reflective article obtained by forming any one of the above optical thin films on a substrate surface. In the antireflective article of the present invention, an organic and / or inorganic binder and fine particles of a metal compound are provided between the surface of the substrate and the optical thin film, and the refractive index is ± of the refractive index of the substrate. A hard coat layer within 0.02 may be formed, and a high refractive index film having a refractive index higher than that of the optical thin film and the hard coat layer is laminated between the hard coat layer and the optical thin film. It can also be formed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be sequentially described with reference to specific embodiments.
First, a method for producing the fluorine-containing compound represented by the general formula (1) will be described. When d of the fluorine-containing compound of the general formula (1) is 0, (meth) acrylic acid represented by the general formula (2) in the chemical formula 3 or (meth) acrylic acid chloride represented by the general formula (3) , And can be produced by esterification reaction with a fluorine-containing compound represented by the general formula (4). The fluorine-containing compound of the general formula (4) can be synthesized by hydrolyzing the compound represented by the general formula (5).
[0012]
[Chemical 3]

[0013]
[Formula 4]

[0014]
[Chemical formula 5]

When d of the compound represented by the general formula (1) is 1, the fluorinated compound represented by the general formula (4) and the isocyanate compound represented by the general formula (6) are urethanized. It can be synthesized by reacting.
[0015]
[Chemical 6]

An isocyanate compound in which c is 1 in the general formula (6) can be preferably used because a compound in which b is 2 can be easily produced. The synthesis by the urethanization reaction is easy and generally easy to use with few side reaction products. In particular, when it is used as an optical thin film, a urethanization reaction that can be reacted in a step of preparing a coating material for forming the optical thin film can be preferably used.
[0016]
Next, the compound represented by the general formula (1) contains at least one of A1, A2, A3, and A4 in the formula, an organic group represented by the general formula (a) other than -H, and By introducing a urethane residue, it can be cured by radical addition polymerization. It was also found that the cured material obtained by polymerization has a low refractive index and usually does not exceed 1.45. Furthermore, by introducing the organic group other than -H into at least two of A1, A2, A3, and A4, it was also found that the cured material obtained by polymerization has high curing performance. For example, it was found that it is suitable for an optical thin film having a low refractive index. In addition, it is expected to be used for various displays, exhibition members, transparent members, and optical equipment components.
[0017]
Now, the case where the compound of the general formula (1) is used as the low refractive index optical thin film of the present invention will be described below. The compound of the general formula (1) can be polymerized and cured by radical thermal polymerization, photopolymerization, electron beam polymerization or the like. In the case of use for an optical thin film, photopolymerization (curing) using ultraviolet rays is preferable because of a high polymerization (curing) speed and ease of equipment. In photopolymerization, in general, an acryloyl group is easier to proceed than a methacryloyl group. Therefore, in order to form an optical thin film, a compound in which any of A1, A2, A3, and A4 has an acryloyl group is suitable. . Of these, compounds having two or more acryloyl groups are preferred.
[0018]
In order to use the compound of the general formula (1) for an optical thin film, it is desirable that the refractive index of the cured product is as low as possible, and a compound in which n is an integer of 2 to 14 can be preferably used. When n is less than 2, the refractive index is hardly lowered sufficiently, and when it is larger than 14, the hardness of the optical thin film tends not to be raised sufficiently. It is more preferable that n is an integer of 4 to 12.
[0019]
In the optical thin film of the present invention, it is necessary to contain at least 45% by weight of the fluorine-containing compound represented by the general formula (1). In addition to the fluorine-containing compound, hardness, adhesion to upper and lower layers, refractive index Other multifunctional monomers can be added for the purpose of adjusting and improving other performance. The addition amount is 20 parts by weight or less, desirably 15 parts by weight or less, with respect to 100 parts by weight of the fluorine-containing compound. When the polyfunctional monomer is added in an amount of 20 parts by weight or more, the refractive index may exceed 1.45, and it tends to be difficult to obtain a desired antireflection performance.
[0020]
Polyfunctional monomers to be added include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meta) ) Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, ditrimethylolpropane tri (Meth) acrylate, 1,1,1-tris [(meth) acryloyloxyethoxyethoxy] propane, tris (hydroxyethyl) isocyanurate Tri (meth) acrylate, tris (hydroxyethyl) isocyanurate di (meth) acrylate. These polyfunctional monomers can be added alone or in admixture of two or more. Preferred additive polyfunctional monomers for the optical thin film of the present invention include trifunctional or higher functional (meth) acrylates that are highly effective in improving hardness.
[0021]
In addition to the above, 100 parts by weight or less, preferably 90 parts by weight of fluorine-containing monofunctional monomer having one unsaturated double bond or 100% by weight of fluorine-containing compound of general formula (1). An amount not exceeding and a polymerization initiator can be added. When the monofunctional monomer exceeds 100 parts by weight, the hardness of the optical thin film tends to decrease. As fluorine-containing monofunctional monomers having one unsaturated double bond, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3 4,4,4-hexafluorobutyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecanol (meth) acrylate, β- (perfluorooctyl) ethyl (meth) acrylate, and the like. These monomers and compounds are appropriately added for adjusting hardness, refractive index, coating property, and the like, and can be cured to form an optical thin film. In order to lower the refractive index of the optical thin film, it is preferable to add a compound having a high fluorine content and containing one unsaturated double bond.
[0022]
In addition, examples of monofunctional monomers not containing fluorine include methyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and the like. As long as a cured film having good compatibility and a refractive index not exceeding 1.45 can be obtained, there is no particular limitation.
[0023]
Further, a leveling agent or a silane coupling agent may be added to improve the coating property. The addition amount is preferably 0.05 to 5% by weight, more preferably 0.1 to 2% by weight, based on the entire cured product.
[0024]
The method for forming an optical thin film of the present invention will be described with reference to an embodiment. The optical thin film of the present invention is mainly used for antireflection of a substrate because of its low refractive index. The optical thin film of the present invention is a composition containing the fluorine-containing compound represented by the general formula (1) alone or, if necessary, a polyfunctional monomer, a polymerization initiator, a monofunctional monomer, a leveling agent, etc. It may be formed by diluting with a suitable solvent, forming a coating agent on the surface of the substrate, polymerizing and curing.
[0025]
Examples of the solvent include alcohols such as propanol, isopropanol, and butanol; ketones such as methyl isobutyl ketone and methyl ethyl ketone; esters such as ethyl acetate; halogens; tetrahydrofuran and the like.
[0026]
The application means is not particularly limited as long as it is a method that can be uniformly applied to a substrate, and spin coating, dip coating, die coating, spray coating, bar coater coating, roll coating, curtain flow coating, and the like can be used. it can.
[0027]
The coating agent is uniformly applied to a substrate to a required thickness and then cured. Although there is no restriction | limiting in particular in the base material which can form the optical thin film of this invention, It can utilize effectively for light reflection prevention, such as glass, resin moldings, such as a polycarbonate and an acrylic resin, films, such as a polyethylene terephthalate film. . In addition, since it has excellent properties such as water repellency and oil repellency, a thin film using them may be formed. There is no restriction | limiting in the shape of a base material.
[0028]
For polymerization and curing, a thermal polymerization method, an electron beam polymerization method, a photopolymerization method (ultraviolet polymerization method), or the like may be used. Among these, a photopolymerization method that is not limited by the heat resistance of the substrate is preferable. When the photopolymerization method is used, it is usually preferable to add a photopolymerization initiator to the coating material in advance. As a photopolymerization initiator, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone -1 etc. can be used. The addition amount of a photoinitiator is 0.1 to 20 weight% of the whole hardened | cured material composition, Preferably it is 0.1 to 10 weight%. A low-pressure or high-pressure mercury lamp or xenon lamp is used as the light source, and the coating substrate is polymerized and cured by irradiating the coated substrate with ultraviolet rays.
[0029]
The optical thin film of the present invention can be formed not only as a single layer on the base material but also laminated with other thin films. For example, the substrate can be surface-treated in order to improve adhesion and applicability, or a hard coat layer can be laminated to improve the hardness of the substrate to make an antireflection article. Furthermore, in order to enhance the antireflection effect of the base material, an optical thin film having a high refractive index can be formed between the base material and the optical thin film of the present invention. By alternately laminating the optical thin film and the high refractive index thin film of the present invention, a more excellent antireflection film can be obtained. The high refractive index film needs to have a refractive index equal to or higher than that of the substrate, specifically preferably at least 1.58, more preferably 1.6 or more, more preferably 1.7 or more. is there.
[0030]
A preferred embodiment example of an antireflection article formed by laminating the optical thin film of the present invention with another thin film will be described. A hard coat layer having a refractive index difference within ± 0.02 and a thickness of about 2 to 5 μm is provided on the surface of the substrate such as polycarbonate or methacrylic resin in order to impart hardness and prevent interference fringes. Hard coat layer, if necessary, add metal oxide fine particles such as Si, Sb, Ce, Ti, Sn to the organic or inorganic binder, that is, fine particles generally having a particle size smaller than the wavelength of visible light The coated film is used. Examples of the organic binder include a cured epoxy resin and a resin obtained by radical crosslinking polymerization, and examples of the inorganic binder include a hydrolyzed cured product of a silane compound, but are not particularly limited. For curing, it is generally preferable to use a photocuring method rather than a heat curing method because the curing speed is high.
[0031]
In order to obtain high antireflection properties, the high refractive index thin film can be laminated on the surface of the hard coat layer. The thickness of the high refractive index film is 90 to 400 nm, more preferably 110 to 180 nm. A high refractive index film is generally a vacuum deposited film of a metal oxide, but contains a metal oxide such as Sb, Ce, Ti, Sn, etc., and is cured using (meth) acrylates, silanes, epoxy resins, etc. as a binder. Layer. When the metal oxide has conductivity, it is preferable because it can provide an electric leakage prevention property. Moreover, if the binder can be cured by a photocuring method, the curing speed is fast and preferable.
[0032]
When one transparent low refractive index film is provided on the base material, a part of the incident reflected light is reflected at the boundary between the air and the thin film, and a part is reflected at the interface between the thin film and the base material. As a result, the reflectance of the substrate is reduced or increased. The low refractive index film is thin enough to cause light interference, and the light reflectivity of the antireflective article depends on the refractive index and film thickness of the low refractive index film.
[0033]
The thickness of the low refractive index film is preferably an odd multiple of λ / 4n (λ: wavelength of light in the thin film, n: refractive index of the thin film). When the wavelength of light is wide, λ is based on the center wavelength of light. In the present invention, the center wavelength is preferably set to 500 to 550 nm. The thickness of the low refractive index film is specifically preferably 30 to 700 nm, more preferably 40 to 120 nm, although it depends on the refractive index of the film. When the thickness of the low refractive index film is less than 30 nm, the reduction of the reflectance due to the light interference effect in visible light may be insufficient. On the other hand, if the film thickness exceeds 700 nm, the reflectivity almost depends only on the reflection at the interface between the air and the thin film, and thus the reflectivity tends to be insufficiently reduced by the optical interference of visible light. For example, when a thin film having a refractive index of 1.38 is formed on a substrate having a refractive index of 1.6, the reflectance is 1% or less if the thickness of the film is appropriate. It will be about 3%. When the refractive index of the low refractive index thin film is 1.45 or more, the antireflection effect of an article based on polymethyl methacrylate or glass having a relatively low refractive index is not significant.
[0034]
【Example】
The present invention will be described more specifically with reference to examples. The evaluation means and measurement means used in the following examples and reference examples are as follows.
a. Film thickness: measured by ellipsometer.
b. Single-sided reflectance: The back surface of the measurement surface was roughened with sandpaper, then blacked with oil-based ink, and the reflectance of the measurement surface at 540 nm was measured using a spectrophotometer.
[0035]
c. Interference fringes: The samples were placed 20 cm below the fluorescent lamp stand and evaluated by visual observation.
d. Scratch resistance: Eraser (No. 50 (manufactured by Lion Corporation)) with a contact area of about 0.5 cm ² and a load of 1 kg, reciprocating 20 times on the reflective surface, and then visually judged and no scratch marks are observed. The pass was judged.
[0036]
[0037]
[0038]
[0039]
Example 1
A reaction solution (CL1) having the composition shown in Table 1 was prepared and reacted at 45 ° C. for 8 hours to synthesize a fluorine-containing compound having a urethane bond. A coating solution C was prepared by adding a reaction solution (CL2) having the composition shown in Table 1 to 502 parts by weight of the resulting reaction solution. The prepared paint C was spin-coated on the surface of a 2 mm thick polycarbonate plate and heated in an oven at 80 ° C. for 10 minutes. A cured film (optical thin film of the present invention) having a thickness of 95 nm was formed by irradiation with 5,000 mJ / cm 2 with a high-pressure mercury lamp . The refractive index of the formed optical thin film is nd = 1. 41. The single-sided reflectance was 1.2%.
[0040]
[Table 1]

Example 2
A paint D having the composition shown in Table 2 was prepared. Using the prepared coating material C, an optical thin film was formed on the surface of the polycarbonate plate in the same manner as in Example 1. The formed optical thin film had a refractive index of nd = 1.40 and a single-sided reflectance of 1.1%.
[0041]
[Table 2]

Examples 3 and 4
Mainly composed of a polycarbonate plate with a thickness of 2 mm and a refractive index nd of 1.59, antimony pentoxide ultrafine particles (average particle diameter (BET method) 20 nm), pentaerythritol triacrylate and 2-hydroxy-3-phenoxyacrylate Refractive index as component 1. 59, a hard coat layer having a thickness of 3 μm was formed by photocuring. The coatings C and D prepared in Examples 1 and 2 were applied to the surface of the formed hard coat layer in the same manner as in Examples 1 and 2, and cured to form the optical thin film of the present invention. Table 3 shows the evaluation results of the formed optical thin film. All of the optical thin films showed high scratch resistance.
[0042]
[Table 3]

Examples 5 and 6
In the same manner as in Examples 3 and 4 , a hard coat layer was formed on a polycarbonate plate having a thickness of 2 mm and a refractive index nd of 1.59. On the surface of the formed hard coat layer, antimony-doped tin oxide ultrafine particles (average particle size (BET method) 40 nm), pentaerythritol triacrylate, 2-hydroxy-3-phenoxyacrylate, the thickness of 150 nm, refraction A conductive high refractive index layer having a ratio nd = 1.70 and a surface resistance of 2 × 10 9 Ω / □ was laminated by photocuring. Further, paints C and D were applied and cured as in Examples 1 and 2 to form the optical thin film of the present invention. Table 4 shows the evaluation results of the formed optical thin film. All of the optical thin films showed high scratch resistance.
[0043]
[Table 4]

Example 7
An ITO film (In2 O3-based transparent highly conductive thin film) having a thickness of 145 nm was formed on a glass plate having a refractive index of nd = 1.53 and a thickness of 2 mm by vacuum deposition. The coating material D prepared in Example 2 was applied to the surface of the ITO film in the same manner as in Example 1 and cured to form the optical thin film of the present invention. The single-sided reflectance of the formed optical thin film was 0.6%.
[0044]
【The invention's effect】
The cured product of the fluorine-containing compound provided by the present invention has a very low refractive index and a high hardness after curing, and is particularly promising as a low refractive index optical thin film. In addition, it has a high surface hardness and excellent scratch resistance and durability. In addition, it has a high effect on water repellency and oil resistance. Moreover, since it is soluble in a solvent before curing, it can be applied and cured by an economical solution coating which can be easily and continuously processed. In addition, the optical thin film of the present invention can be formed on a hard coat layer or a high refractive index film to further improve the scratch resistance and anti-light reflection performance and to provide multi-functionality. In addition to the optical thin film, it is expected to be used for various display materials, display members, transparent members, and constituent materials of optical equipment.

Claims (11)

An optical thin film obtained by curing a composition containing the compound represented by the general formula (1) and having a refractive index of 1.45 or less.

      2. The optical thin film according to claim 1, wherein the film thickness is 30 to 700 nm.       The optical thin film according to claim 1 or 2, wherein the compound represented by the general formula (1) is a compound in which n is any integer of 4 to 12.       The optical thin film according to any one of claims 1 to 3, wherein the compound represented by the general formula (1) has an acryloyl group in any one of A1, A2, A3, and A4. Relative to 100 parts by weight of the compound represented by the general formula (1), the optical according to claim 1, characterized by containing a polyfunctional (meth) acrylate 0-20 parts by weight Thin film. The optical thin film according to any one of claims 1 to 5 , comprising 0 to 100 parts by weight of a monofunctional (meth) acrylate with respect to 100 parts by weight of the compound represented by the general formula (1). . The optical thin film according to claim 1 , which is cured by light. The optical thin film according to any one of claims 1 to 7 , wherein a solvent of the composition containing the compound represented by the general formula (1) is prepared, applied to the surface of the base material, and cured by irradiation with light. A method for forming an optical thin film, comprising: forming an optical thin film. An optical antireflective article comprising the optical thin film according to any one of claims 1 to 7 formed on a substrate surface. A hard coat layer composed of organic and / or inorganic binder and metal compound fine particles and having a refractive index within ± 0.02 of the refractive index of the substrate is formed between the substrate surface and the optical thin film. The antireflective article according to claim 9 , wherein the antireflective article is provided. 11. The antireflection according to claim 10 , wherein a high refractive index film having a refractive index higher than that of the optical thin film and the hard coat layer is laminated between the hard coat layer and the optical thin film. Sex goods.