JP2004198464A - Material for color filter protective film, and color filter protective film - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、カラーフィルタの保護膜を与えるカラーフィルタ保護膜用材料及びこれを硬化して得られるカラーフィルタ保護膜に関するものである。詳しくは、塗膜形成材料として種々の塗膜物性に優れ、特に保存安定性および膜厚均一性に優れたカラーフィルタ保護膜用材料およびカラーフィルタ保護膜に関するものである。
【０００２】
【従来の技術】
カラー液晶表示装置に使われるカラーフィルタとして、着色性感光性樹脂による赤色（Ｒ）、緑色（Ｇ）、青色（Ｂ）のパターンがフォトリソ法などで形成されたものが知られている。そして、ガラス基板上に形成されたＲ、Ｇ、Ｂのカラーフィルタのパターン上には、表示品位向上のための平滑性、平坦性の付与、ＩＴＯ成膜時のスパッタダメージからのＲ、Ｇ、Ｂの保護、Ｒ、Ｇ、Ｂと液晶が接触することでイオン性不純物による液晶汚染が発生することを抑制するために保護膜が設けられることが多い。ところで、このようなカラーフィルタ保護膜（以下、単に保護膜ともいう）に要求される性能としては、耐熱性、平坦性、耐薬品性、接着性、透明性、平滑性、耐候性などが挙げられる。そして、このような保護膜を得るためのカラーフィルタ保護膜用材料に要求される性能としては、塗布性、溶剤の身体への安全性、保存安定性等が挙げられる。
【０００３】
保護膜は、通常スピンコーター、ロールコーター、バーコーター等の塗布装置を用いて塗布されたのち、溶剤を除くためにオーブンやホットプレートで加熱乾燥するか、減圧乾燥装置で減圧乾燥を行い、均一な塗膜を形成する。オーブンやホットプレートを使用する場合には、均一な加熱が行なわれず熱ムラが発生する。その結果、カラーフィルタの表示領域に雲状のムラが発生し、表示品位を落とす。一方、減圧乾燥による場合は急激な溶剤の揮発により蒸発ムラが発生し、オーブンやホットプレートと同様、カラーフィルタの表示領域に雲状のムラが発生する。
【０００４】
このような塗布ムラの発生傾向は、単一の溶剤を用いた場合に特に顕著である。従来より、塗布性を向上させるため高沸点の溶剤との併用が行われてきているが、高沸点溶剤を併用した場合、乾燥時間が長くなるほか、保護膜表面にタックが残りやすくなり、その結果、異物も付着しやすい。例えば、スピンコートによる保護膜膜厚の不均一性を防止するため、高沸点の溶剤を用いて、塗布時の溶剤蒸発を抑制する方法が特開２０００−８６９０６号公報（特許文献１）に提案されている。しかしこの方法は沸点１９０℃以上の溶剤を全溶剤の３０〜６０重量％含むため、真空乾燥時の乾燥時間が長くなるほか、保護膜表面にタックが残りやすくなり、その結果、異物も付着しやすいという欠点を有する。
【０００５】
その他の溶剤のうち、セロソロブ類あるいはセロソロブアセテート類あるいはジエチレングリコールモノアルキルエーテル類あるいはジエチレングリコールジアルキルエーテル類およびハロゲン系溶剤は、塗布性は優れているが、人体への安全性が低い。またプロピレングリコールモノアルキルエーテル等のアルコール性水酸基を含む溶剤は、エポキシ基を含む樹脂と硬化剤の反応を促進し、材料の粘度を増加させるため、保存安定性が悪い。
【０００６】
一般に、塗布性の向上のためには界面活性剤の添加が有効であることが知られているが、スピンコート時のガラス基板周辺部におけるレジスト液の戻りが生じ易く、塗布ムラとレジスト液の戻り幅のバランスをとり難いという問題がある。このような事情から、カラーフィルタの保護膜として用いられる材料として、塗布性及び保存安定性に優れ且つ安全性の高い溶剤が望まれていた。
【特許文献１】
特開２０００−８６９０６号公報
【０００７】
【発明が解決しようとする課題】
本発明の目的は、従来のカラーフィルタ保護膜用材料の欠点を解消し、塗布ムラが生じにくく、塗布性及び保存安定性に優れ、安全性の高い溶剤を使用したカラーフィルタ保護膜用材料を提供することを目的とする。また、本発明は当該カラーフィルタ保護膜用材料による硬化膜を提供することでもある。
【０００８】
【課題を解決するための手段】
本発明者らは、上述の問題点を解決すべく鋭意検討を行なった結果、カラーフィルタ保護膜用材料に使用する溶剤として、ジプロピレングリコールジメチルエーテルを必須成分として含有する溶剤を用いることで塗布ムラ等で評価される塗布性が著しく改良されることを見出し、本発明を完成した。
【０００９】
すなわち、本発明は、エポキシ基を含む樹脂（Ａ）、硬化剤（Ｂ）および溶剤（Ｃ）を主成分とする材料であって、全溶剤中のジプロピレングリコールジメチルエーテル（ＤＭＭ）の割合が５〜８０重量％であることを特徴とするカラーフィルタ保護膜用材料である。前記エポキシを含む樹脂（Ａ）としては、一般式（１）
【化２】
【００１０】
【発明の実施の形態】
以下に本発明を詳細に説明する。
本発明のカラーフィルタ保護膜用材料は、（Ａ）成分：エポキシ基を含む樹脂、（Ｂ）成分：硬化剤、および（Ｃ）成分：溶剤を主成分とする。以下、（Ａ）成分、（Ｂ）成分および（Ｃ）成分の順に説明する。
【００１１】
（Ａ）成分であるエポキシ基を含む樹脂は、特に制限されず、広く一般に知られるエポキシ樹脂を用いればよい。例えば、新保正樹編、エポキシ樹脂ハンドブック、日刊工業新聞社刊（昭和６２年）等に記されたエポキシ樹脂を用いることが出来る。本発明のエポキシ基を含む樹脂には、繰り返し構造単位のないいわゆるエポキシ化合物と呼ばれるものも含まれる。具体例としては、一般式（１）で表されるエポキシ樹脂(以下、カルドエポキシ樹脂と称する)、ビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、クレゾールノボラック型エポキシ樹脂、脂環式エポキシ樹脂等を挙げることが出来る。
【００１２】
中でもカルドエポキシ樹脂は、保護膜に優れた平坦性、透明性、耐熱性や表面硬度を付与するために有利に用いられる。カルドエポキシ樹脂は、特開昭６３−２１８７２５号公報に開示されており、ビスフェノールフルオレンとエピクロルヒドリンの反応で得ることが出来る。
エポキシ樹脂は、２種類以上混合して使用することができ、本発明においては、２種類あるいは３種類を混合して使用することが好ましい。例えば上記カルドエポキシ樹脂と、平坦性に優れた脂環式エポキシ樹脂、耐熱性に優れたノボラック型エポキシ樹脂の２種類または３種類を混合して使用することで、平坦性と耐熱性をバランス良く両立することが可能となる。
【００１３】
（Ｂ）成分である硬化剤は、公知のものを使用することができ、例えば前述した成書（新保正樹編、エポキシ樹脂ハンドブック、日刊工業新聞社刊（昭和６２年）にその具体例が例示されている。具体的には、酸系硬化剤及び酸無水物系硬化剤で、例えば、無水トリメリット酸、無水ピロメリット酸、無水フタル酸等が好ましいものとして挙げられる。
【００１４】
また、特開平４−２１８５６１号公報には特定構造を有するブロック化カルボン酸化合物が提案されており、これを酸硬化剤として用いることも出来る。ブロック化カルボン酸化合物は所定温度以上で、カルボン酸を保護していたビニルエーテル化合物又はビニルチオエーテル化合物が脱離して酸硬化剤として作用する。
【００１５】
（Ａ）成分であるエポキシ基を含む樹脂と（Ｂ）成分である硬化剤の割合は、得られる保護膜の硬度、耐熱性、耐薬品性等の物性が要求特性を満たすように決定される。硬化剤に、酸系硬化剤及び酸無水物系硬化剤を使用する場合には、エポキシ樹脂が有するエポキシ基と酸系硬化剤及び酸無水物系硬化剤の有するカルボキシル基（ブロック化されたカルボキシル基を含む。以下、この項において同じ。）の比率で選択される。ここで、比率の計算は、例えば、酸系硬化剤及び酸無水物系硬化剤１分子中のカルボキシル基数がｎ個、エポキシ化合物１分子中のエポキシ基の数がｍ個であるとすると、それぞれの化合物１モルあたり、ｎ当量のカルボキシル基、ｍ当量のエポキシ基を有するとして計算される。耐熱性に着目すると、カルボキシル基／エポキシ基の当量比が、０．４〜１．４、好ましくは、０．６〜１．２、より好ましくは、０．８〜１．０となるようにエポキシ樹脂と酸系硬化剤及び酸無水物系硬化剤を配合することがよい。当量比が０．４より小さいと、得られる硬化物の耐熱性が低く、更にガラス基板との密着性が低い等の問題が生じ、逆に、１．４より大きいと得られる硬化物の耐熱性が低い等の問題が生じる。その他の特性についても、カルボキシル基／エポキシ基の当量比を、０．４〜１．４、好ましくは、０．６〜１．２の範囲とすることがよい。
【００１６】
本発明においては、エポキシ樹脂と酸系硬化剤及び酸無水物系硬化剤の反応を促進する目的で硬化触媒を用いることが出来る。但し、エポキシ樹脂と硬化剤を混合して１つのレジストとして使用する場合は、保存安定性を十分に考慮する必要がある。触媒の添加量は、エポキシ樹脂と硬化剤の合計１００重量部に対して、触媒の有効成分が通常０．０１〜５重量部の範囲で選ばれる。なお、これらの重量計算においては、エポキシ樹脂、硬化剤に溶剤等が含まれる場合はその分を重量計算に含めない。本発明の保護膜用材料は、保存安定性を向上させる目的で、エポキシ樹脂と硬化剤を２液に分けて使用することが可能である。
【００１７】
（Ｃ）成分である溶剤は、直鎖のジグリコールエーテルであるジプロピレングリコールジメチルエーテル（略称：ＤＭＭ）を必須溶剤成分として含む。本発明においては、ＤＭＭと少なくとも１種以上のＤＭＭ以外の溶剤との混合溶剤からなり、他の広く一般に用いられる溶剤を併用して用いることができる。樹脂の溶解性および乾燥性に着目すると、全溶剤中のＤＭＭの比率は、５〜８０重量％であり、好ましくは、５〜６０重量％、より好ましくは、５〜４０重量％となるように配合することがよい。全溶剤中のＤＭＭの割合が５重量％に満たないと、良好な塗布性が得られず、また、８０重量％を超えると乾燥時間が長くなるほか、保護膜表面にタックが残りやすくなり、その結果、異物も付着しやすくなる。
【００１８】
ＤＭＭと併用できる他の溶剤としては、上記（Ａ）成分及び（Ｂ）成分を溶解し、ＤＭＭと相溶性があり、乾燥条件で蒸発する沸点を有するものであればよく、この分野で使用される公知の溶剤が広く例示される。併用溶剤の好ましいものを下記に例示するが、本発明は、これら具体的に例示された溶剤に限定されるものではない。
【００１９】
ＤＭＭとの併用溶剤としては、メチルエチルケトン、シクロヘキサノン、メチルシクロヘキサノン等のケトン類、プロピレングリコールモノメチルエーテル、プロピレングリコールモノエチルエーテル、プロピレングリコールn-プロピルエーテル、プロピレングリコールn-ブチルエーテル等のプロピレングリコールモノアルキルエーテル類、プロピレングリコールモノメチルエーテルアセテート、プロピレングリコールモノエチルエーテルアセテート、プロピレングリコールn-プロピルエーテルアセテート、プロピレングリコールn-ブチルエーテルアセテート等のプロピレングリコールモノアルキルエーテルアセテート類、乳酸メチル、乳酸エチル等の乳酸エステル類、酢酸n-ブチル等の酢酸エステル類の他、ガンマ−ブチロラクトン、Ｎ−メチルピロリドン、ジメチルスルホキシド等が有用なものとして例示される。好ましくはプロピレングリコールモノメチルエーテルアセテート、３−メトキシブチルアセテート、酢酸ｎ−ブチル等が有用なものとして例示される。
【００２０】
これらはＤＭＭより沸点が低く、蒸気圧が高いため、保護膜表面にタックが残りにくくなるので好ましい。特に好ましいＤＭＭとの併用溶剤は、常圧での沸点が１７５℃以下で、かつ、20℃における蒸気圧が0.7〜18 mmHgの範囲にあるものである。プロピレングリコールモノメチルエーテルアセテート（146℃，3.7 mmHg）、３−メトキシブチルアセテート（173℃，3.0 mmHg）、酢酸ｎ−ブチル（126℃，13 mmHg）はこの要件を満たすものである。ここで、カッコ内の数値は、前者が常圧での沸点を、後者が20℃における蒸気圧の値を示したものである。
【００２１】
上記他の溶剤のうち、セロソロブ類あるいはセロソロブアセテート類あるいはジエチレングリコールモノアルキルエーテル類あるいはジエチレングリコールジアルキルエーテル類およびハロゲン系溶剤は、塗布性は優れているが、人体への安全性が低いため近い将来使用できなくなる可能性がある。ジプロピレングリコールジアルキルエーテル、ジプロピレングリコールモノアルキルエーテル、およびプロピレングリコールジエステル等のプロピレングリコール骨格を有する有機溶剤は安全性が高く、作業環境の面から工業的に重要な溶剤である。
【００２２】
本発明の保護膜用材料には、本発明の効果を損なわない範囲であれば、他の成分を含有してもよい。例えば、濡れ性の向上のためには界面活性剤が、密着性向上のためにはカップリング剤が好ましく使用される。この場合、界面活性剤は０．０１〜０．２重量％の範囲で含有させることが好ましい。
【００２３】
保護膜用材料を調製する方法に特に限定はないが、エポキシ樹脂、硬化剤、溶剤、光重合開始剤、界面活性剤、カップリング剤の種類、配合量を適宜調整した後、ロールミル、ボールミル、サンドミル、プラネタリーミキサーなどの分散、混合装置を用い、５〜７０℃で１〜５０時間程度撹拌混合を行い、均一な組成となるように溶解させる方法を採用することができる。
【００２４】
本発明の保護膜用材料は、塗布性を確保するために溶液状である必要があり、そのために（Ｃ）成分の溶剤は全体の５０重量％以上、好ましくは６０〜９０重量％であることがよい。有利には、２３℃における粘度が３〜１５ｍＰａ・ｓであることが好ましい。粘度が３ｍＰａ・ｓより低いとスピンコートで塗布するには非現実的であり、一方、１５ｍＰａ・ｓより高いとスピンコートで塗布しにくい。またスピンコート法において、材料の使用量を減らし、かつ塗布ムラを少なくすることが出来る注液方式に、スリット方式がある。３〜１５ｍＰａ・ｓの粘度はスリット方式に適当である。
【００２５】
【実施例】
以下、実施例により本発明を、更に詳しく説明するが、本発明はこれに限定されるものではない。なお、実施例中、別段の断りがない限り、部は重量部を表し、％は重量％を表す。また、カラーフィルタ保護膜の作成及び塗布ムラの評価は別段の断りがない限り、以下の方法による。
【００２６】
（保護膜の作成）
ポストベーク後の膜厚が２±０．０５μｍとなるスピンコート条件でカラーフィルタ保護膜用組成物を、ＳｉＯ2をコーティングしたガラス基板に塗布し、プレベーク８０℃、１０分で溶剤を蒸発させた後、ポストベーク２００℃、３０分で硬化させ、保護膜を作成した。一方、減圧乾燥を実施する場合は、同様にガラス基板にスピンコート塗布したのち、減圧のできるチャンバーの中に置き、１分以内で大気圧〜５０Ｐａまで減圧することで溶剤を留去させ、同様にプレベークで残りの溶剤を蒸発させた後、ポストベークで硬化させ、保護膜を作成した。
【００２７】
（塗布ムラの評価）
ガラス基板に塗布した膜厚が２±０．０５μｍの保護膜を、ナトリウムランプ光源下で目視により塗布ムラを観察した。塗膜にムラの無い状態を◎、ムラの有る状態を×、ムラは目視で確認できるが実用性に問題のない軽微な状態を○とし、塗布ムラを◎、○、×の３段階で評価した。
【００２８】
（額縁幅の評価）
ガラス基板に塗布した膜厚が２±０．０５μｍの保護膜を、ナトリウムランプ光源下で目視により額縁幅を観察した。額縁幅はガラス基板の端面から中心に向かい３〜３０ｍｍ程度の帯状のムラとして観察される。額縁幅が１０ｍｍ以内の状態を○、１０ｍｍを越える状態を×とし、塗布ムラを○、×の２段階で評価した。
【００２９】
（粘度の評価）
保護膜用材料の粘度測定は、ＢＬ型粘度計（東洋精機(株)製）を用いた。材料を測定容器に入れＢＬアダプターを設置する。容器ごと恒温槽に漬けて２３℃に保った後、３０ｒｐｍの条件で開始１分後の値を計測した。
【００３０】
（保存安定性の評価）
調製直後の材料の粘度をＶ１とする。次に４０℃の恒温槽に７日間浸漬した後の材料の粘度をＶ２とする。Ｖ２／Ｖ１の値が、１．０〜１．３と粘度増加が小さい状態を○、１．３を超えて粘度増加が大きい状態を×とし、保存安定性を○、×の２段階で評価した。
【００３１】
実施例１
サンプル瓶（200ml）にテフロン（登録商標）被覆した回転子を入れ、マグネチックスターラーに設置した。ＤＭＭ４ｇ、プロピレングリコールモノメチルエーテルアセテート（ＰＧＭＥＡ）７４ｇをサンプル瓶に入れた。攪拌しながら、カルドエポキシ樹脂：ESF-300（新日鐵化学(株)製）１．２ｇ、フェノールノボラック型エポキシ樹脂：エピコート154（ジャパンエポキシレジン(株)製）１１．４ｇ、脂環式エポキシ樹脂：EHPE-3150（ダイセル化学工業(株)製）１１．４ｇを加え、完全に溶解させた。引き続き、無水トリメリット酸を５．３ｇ加え、十分に攪拌溶解した後に、シランカップリング剤１ｇ、界面活性剤０．１ｇを加えて十分に攪拌した。これをろ過して、カラーフィルタ保護膜用材料を得た。
【００３２】
得られた保護膜用組成物を用いて、前述の評価方法に従い、ガラス基板上に保護膜を形成し、ナトリウムランプ光源下で塗布ムラを観察し、塗布性を◎、○、×の３段階で評価した。表１に結果を示す。保護膜用材料が塗布性に優れることが確認される。
【００３３】
実施例２
溶剤の使用量を、ＤＭＭ２３ｇ、ＰＧＭＥＡ５５ｇと変化させたこと以外は実施例１と同様に行った。結果を表１に示す。保護膜用組成物が塗布性に優れることが確認される。
【００３４】
実施例３
溶剤の使用量を、ＤＭＭ６３ｇ、ＰＧＭＥＡ１６ｇと変化させたこと以外は実施例１と同様に行った。結果を表１に示す。保護膜用組成物が塗布性に優れることが確認される。
【００３５】
実施例４
溶剤を、ＤＭＭとＰＧＭＥＡとの併用系として、表１の組成としたこと以外は実施例１と同様に行った。表１に結果を示す。塗布性はやや劣るが、実用性に問題ないことが確認される。
【００３６】
比較例１
溶剤にＰＧＭＥＡのみを使用して実施例１と同様に保護膜用材料の調整を行おうとしたが、エポキシ樹脂の溶解の時点で十分に攪拌溶解したにもかかわらずエポキシ樹脂が完全に溶解しなかったため、他の成分の添加はしなかった。そのため、目的とするカラーフィルタ保護膜用材料を得ることができなかった。
【００３７】
比較例２
溶剤にDMMを使用せず、ＰＧＭＥＡとプロピレングリコールモノメチルエーテル（ＰＧＭＥ）の併用系とし、表１の組成としたこと以外は実施例１と同様に行った。結果を表１に示す。実施例記載の保護膜用組成物に比較して塗布性に劣ることが確認される。また保存安定性も劣ることが確認される。
【００３８】
比較例３
溶剤にDMMを使用せず、ＰＧＭＥＡとジプロピレングリコールモノメチルエーテルアセテート（ＤＰＭＡ）の併用系とし、表１の組成としたこと以外は実施例１と同様に行った。表１に結果を示す。実施例の保護膜組成物に比較して塗布性に劣ることが確認される。また額縁幅が広いことが確認される。
【００３９】
【表１】
【発明の効果】
本発明のカラーフィルタ保護膜用材料は塗布性、保存安定性に優れており、また、これを用いて形成したカラーフィルタ用保護膜は塗布ムラが無いことから平坦性、狭額縁幅による膜厚均一性に優れている。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a material for a color filter protective film that provides a protective film for a color filter, and a color filter protective film obtained by curing the material. More specifically, the present invention relates to a material for a color filter protective film and a color filter protective film excellent in various coating film physical properties as a film forming material, particularly excellent in storage stability and film thickness uniformity.
[0002]
[Prior art]
2. Description of the Related Art As a color filter used in a color liquid crystal display device, a color filter in which a red (R), green (G), and blue (B) pattern formed of a coloring photosensitive resin is formed by a photolithography method or the like is known. On the R, G, and B color filter patterns formed on the glass substrate, smoothness and flatness for improving display quality, and R, G, and B from sputter damage during ITO film formation are provided. A protective film is often provided to protect B, and to suppress the occurrence of liquid crystal contamination due to ionic impurities due to contact between R, G, and B and the liquid crystal. By the way, the performance required of such a color filter protective film (hereinafter, also simply referred to as a protective film) includes heat resistance, flatness, chemical resistance, adhesiveness, transparency, smoothness, weather resistance and the like. Can be The performance required of a material for a color filter protective film for obtaining such a protective film includes applicability, safety of a solvent to the body, storage stability, and the like.
[0003]
The protective film is usually applied using a coating device such as a spin coater, roll coater, bar coater, etc., and then dried by heating in an oven or a hot plate to remove the solvent, or by drying under reduced pressure using a vacuum drying device, and then uniform. To form a perfect coating film. When an oven or a hot plate is used, uniform heating is not performed and heat unevenness occurs. As a result, cloud-like unevenness occurs in the display area of the color filter, deteriorating the display quality. On the other hand, in the case of drying under reduced pressure, evaporation unevenness occurs due to rapid volatilization of the solvent, and cloud-like unevenness occurs in the display area of the color filter as in an oven or a hot plate.
[0004]
Such a tendency of application unevenness is particularly remarkable when a single solvent is used. Conventionally, a combination with a high-boiling solvent has been used to improve coating properties.However, when a high-boiling solvent is used in combination, the drying time becomes longer and tack tends to remain on the protective film surface. As a result, foreign matter is also likely to adhere. For example, Japanese Patent Application Laid-Open No. 2000-86906 proposes a method of using a solvent having a high boiling point to suppress solvent evaporation during coating in order to prevent nonuniformity in the thickness of the protective film due to spin coating. Have been. However, this method contains a solvent having a boiling point of 190 ° C. or higher in an amount of 30 to 60% by weight of the total solvent, so that the drying time in vacuum drying is prolonged, and the tack tends to remain on the surface of the protective film. It has the disadvantage of being easy.
[0005]
Among other solvents, cellosolobs, cellosolob acetates, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, and halogen-based solvents are excellent in coatability but low in safety to the human body. Further, a solvent containing an alcoholic hydroxyl group such as propylene glycol monoalkyl ether promotes a reaction between a resin containing an epoxy group and a curing agent and increases the viscosity of the material, so that storage stability is poor.
[0006]
In general, it is known that the addition of a surfactant is effective for improving the coating property. However, the resist liquid tends to return in the peripheral portion of the glass substrate during spin coating, and coating unevenness and the resist liquid are likely to occur. There is a problem that it is difficult to balance the return width. Under such circumstances, as a material used as a protective film of a color filter, a solvent having excellent coatability and storage stability and high safety has been desired.
[Patent Document 1]
JP 2000-86906 A
[Problems to be solved by the invention]
An object of the present invention is to solve the drawbacks of the conventional material for a color filter protective film, to prevent coating unevenness from occurring, to have excellent coatability and storage stability, and to provide a material for a color filter protective film using a highly safe solvent. The purpose is to provide. Another object of the present invention is to provide a cured film made of the material for a color filter protective film.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a solvent containing dipropylene glycol dimethyl ether as an essential component is used as a solvent for a material for a color filter protective film, so that coating unevenness is caused. The present inventors have found that the applicability evaluated by the method described above is significantly improved and completed the present invention.
[0009]
That is, the present invention relates to a material containing a resin (A) containing an epoxy group, a curing agent (B), and a solvent (C) as main components, wherein the proportion of dipropylene glycol dimethyl ether (DMM) in all solvents is 5%. It is a material for a color filter protective film, characterized in that the content is about 80% by weight. As the epoxy-containing resin (A), general formula (1)
Embedded image
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The material for a color filter protective film of the present invention comprises, as main components, component (A): a resin containing an epoxy group, component (B): a curing agent, and component (C): a solvent. Hereinafter, the components (A), (B) and (C) will be described in order.
[0011]
The resin containing an epoxy group, which is the component (A), is not particularly limited, and an epoxy resin widely and generally known may be used. For example, epoxy resins described in Masaki Shinbo, Epoxy Resin Handbook, published by Nikkan Kogyo Shimbun (1987) and the like can be used. The resin containing an epoxy group of the present invention includes a so-called epoxy compound having no repeating structural unit. Specific examples include an epoxy resin represented by the general formula (1) (hereinafter referred to as cardo epoxy resin), a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, Alicyclic epoxy resins and the like can be mentioned.
[0012]
Above all, cardo epoxy resin is advantageously used for imparting excellent flatness, transparency, heat resistance and surface hardness to the protective film. The cardo epoxy resin is disclosed in JP-A-63-218725, and can be obtained by reacting bisphenolfluorene with epichlorohydrin.
Two or more epoxy resins can be used as a mixture, and in the present invention, two or three kinds are preferably used as a mixture. For example, by using a mixture of two or three of the above cardo epoxy resin, an alicyclic epoxy resin having excellent flatness, and a novolak type epoxy resin having excellent heat resistance, the flatness and heat resistance are well-balanced. It is possible to achieve both.
[0013]
As the curing agent as the component (B), a known curing agent can be used, and specific examples thereof are given in, for example, the above-mentioned book (edited by Masaki Shinbo, epoxy resin handbook, published by Nikkan Kogyo Shimbun (1987)). Specifically, preferred examples of the acid-based curing agent and the acid-anhydride-based curing agent include trimellitic anhydride, pyromellitic anhydride, and phthalic anhydride.
[0014]
Japanese Patent Application Laid-Open No. 4-218561 proposes a blocked carboxylic acid compound having a specific structure, which can be used as an acid curing agent. At a predetermined temperature or higher, the blocked carboxylic acid compound releases the vinyl ether compound or vinyl thioether compound which protected the carboxylic acid, and acts as an acid curing agent.
[0015]
The ratio of the resin containing an epoxy group as the component (A) and the curing agent as the component (B) is determined so that physical properties such as hardness, heat resistance, and chemical resistance of the obtained protective film satisfy required characteristics. . When an acid-based curing agent and an acid-based curing agent are used as the curing agent, the epoxy group of the epoxy resin and the carboxyl group (blocked carboxyl group) of the acid-based curing agent and the acid-based curing agent are used. And the same applies hereinafter in this section). Here, the calculation of the ratio is, for example, assuming that the number of carboxyl groups in one molecule of the acid-based curing agent and the acid anhydride-based curing agent is n and the number of epoxy groups in one molecule of the epoxy compound is m. Is calculated as having n equivalents of carboxyl groups and m equivalents of epoxy groups per mole of the compound. Focusing on heat resistance, the equivalent ratio of carboxyl group / epoxy group should be 0.4 to 1.4, preferably 0.6 to 1.2, and more preferably 0.8 to 1.0. It is preferable to mix an epoxy resin with an acid-based curing agent and an acid anhydride-based curing agent. When the equivalent ratio is smaller than 0.4, the resulting cured product has low heat resistance and further has a problem of low adhesion to a glass substrate. Conversely, when the equivalent ratio is larger than 1.4, the obtained cured product has low heat resistance. Problems such as poor performance occur. Regarding other properties, the equivalent ratio of carboxyl group / epoxy group may be in the range of 0.4 to 1.4, preferably 0.6 to 1.2.
[0016]
In the present invention, a curing catalyst can be used for the purpose of accelerating the reaction of the epoxy resin with the acid-based curing agent and the acid-based curing agent. However, when an epoxy resin and a curing agent are mixed and used as one resist, it is necessary to sufficiently consider storage stability. The amount of the catalyst to be added is generally selected from the range of 0.01 to 5 parts by weight of the active ingredient of the catalyst based on 100 parts by weight of the total of the epoxy resin and the curing agent. In these weight calculations, when a solvent or the like is contained in the epoxy resin or the curing agent, the amount thereof is not included in the weight calculation. In the material for a protective film of the present invention, an epoxy resin and a curing agent can be used separately in two liquids for the purpose of improving storage stability.
[0017]
The solvent as the component (C) contains dipropylene glycol dimethyl ether (abbreviation: DMM) which is a linear diglycol ether as an essential solvent component. In the present invention, a mixed solvent of DMM and at least one or more solvents other than DMM can be used in combination with other widely used solvents. Focusing on the solubility and drying properties of the resin, the proportion of DMM in the total solvent is 5 to 80% by weight, preferably 5 to 60% by weight, and more preferably 5 to 40% by weight. It is good to mix. If the proportion of DMM in the total solvent is less than 5% by weight, good coating properties cannot be obtained, and if it exceeds 80% by weight, the drying time becomes longer and tack tends to remain on the protective film surface, As a result, foreign matter also easily adheres.
[0018]
Other solvents that can be used in combination with DMM may be any solvent that dissolves the above components (A) and (B), is compatible with DMM, and has a boiling point that evaporates under dry conditions. Well-known solvents are widely exemplified. Preferred examples of the combined solvent are shown below, but the present invention is not limited to these specifically exemplified solvents.
[0019]
Examples of the solvent used in combination with DMM include ketones such as methyl ethyl ketone, cyclohexanone and methyl cyclohexanone, and propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol n-propyl ether and propylene glycol n-butyl ether. Propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol n-propyl ether acetate, propylene glycol n-butyl ether acetate, lactic acid esters such as methyl lactate and ethyl lactate, and acetic acid. In addition to acetates such as n-butyl, gamma-butyrolactone, N-methyl Rupyrrolidone, dimethyl sulfoxide and the like are exemplified as useful ones. Preferably, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, n-butyl acetate and the like are exemplified as useful ones.
[0020]
These are preferable because they have a lower boiling point and a higher vapor pressure than DMM, so that tackiness hardly remains on the surface of the protective film. Particularly preferred solvents used in combination with DMM are those having a boiling point at normal pressure of 175 ° C. or lower and a vapor pressure at 20 ° C. of 0.7 to 18 mmHg. Propylene glycol monomethyl ether acetate (146 ° C, 3.7 mmHg), 3-methoxybutyl acetate (173 ° C, 3.0 mmHg), and n-butyl acetate (126 ° C, 13 mmHg) satisfy this requirement. Here, the numerical value in parentheses indicates the boiling point at normal pressure for the former, and the vapor pressure value at 20 ° C. for the latter.
[0021]
Among the other solvents, cellosolops or cellosolov acetates or diethylene glycol monoalkyl ethers or diethylene glycol dialkyl ethers and halogen-based solvents are excellent in coating properties, but are low in safety to the human body, and will be used in the near future. May be unusable. Organic solvents having a propylene glycol skeleton, such as dipropylene glycol dialkyl ether, dipropylene glycol monoalkyl ether, and propylene glycol diester, have high safety and are industrially important from the viewpoint of working environment.
[0022]
The material for a protective film of the present invention may contain other components as long as the effects of the present invention are not impaired. For example, a surfactant is preferably used for improving wettability, and a coupling agent is preferably used for improving adhesion. In this case, the surfactant is preferably contained in the range of 0.01 to 0.2% by weight.
[0023]
Although there is no particular limitation on the method of preparing the material for the protective film, the epoxy resin, the curing agent, the solvent, the photopolymerization initiator, the surfactant, the type of the coupling agent, after appropriately adjusting the compounding amount, a roll mill, a ball mill, Using a dispersing and mixing apparatus such as a sand mill or a planetary mixer, a method of performing stirring and mixing at 5 to 70 ° C. for about 1 to 50 hours to dissolve so as to have a uniform composition can be adopted.
[0024]
The material for a protective film of the present invention needs to be in a solution state in order to ensure coatability, and therefore, the solvent of the component (C) should be 50% by weight or more, preferably 60 to 90% by weight of the whole. Is good. Advantageously, the viscosity at 23 ° C. is preferably 3 to 15 mPa · s. If the viscosity is lower than 3 mPa · s, it is impractical to apply by spin coating. On the other hand, if the viscosity is higher than 15 mPa · s, it is difficult to apply by spin coating. In the spin coating method, there is a slit method as a liquid injection method capable of reducing the amount of material used and reducing coating unevenness. A viscosity of 3 to 15 mPa · s is suitable for the slit method.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In Examples, unless otherwise specified, parts represent parts by weight and% represents weight%. Further, the preparation of the color filter protective film and the evaluation of the coating unevenness are performed by the following methods unless otherwise specified.
[0026]
(Creation of protective film)
The composition for a color filter protective film was applied to a glass substrate coated with SiO 2 under spin coating conditions under which the film thickness after post-baking was 2 ± 0.05 μm, and the solvent was evaporated at 80 ° C. for 10 minutes in pre-baking. Thereafter, the film was cured at 200 ° C. for 30 minutes in post-baking to form a protective film. On the other hand, when carrying out drying under reduced pressure, after spin-coating the glass substrate in the same manner, placing it in a chamber capable of reducing pressure, distilling off the solvent by reducing the pressure to atmospheric pressure to 50 Pa within 1 minute, The remaining solvent was evaporated by pre-baking, and then cured by post-baking to form a protective film.
[0027]
(Evaluation of coating unevenness)
The coating unevenness of the protective film having a thickness of 2 ± 0.05 μm applied to the glass substrate was visually observed under a sodium lamp light source. A state where there is no unevenness in the coating film is indicated by ◎, a state where there is unevenness is indicated by x, and a non-uniform state which can be visually confirmed but there is no problem in practicality is indicated by ○, and coating unevenness is evaluated in three stages of ◎, ○ and × did.
[0028]
(Evaluation of frame width)
The frame width of the protective film having a thickness of 2 ± 0.05 μm applied to the glass substrate was visually observed under a sodium lamp light source. The frame width is observed as a band-like unevenness of about 3 to 30 mm from the end face of the glass substrate toward the center. A state in which the frame width was within 10 mm was rated as ○, and a state in which the frame width exceeded 10 mm was rated as ×, and coating unevenness was evaluated in two stages of ○ and ×.
[0029]
(Evaluation of viscosity)
The viscosity of the material for the protective film was measured using a BL viscometer (manufactured by Toyo Seiki Co., Ltd.). The material is put in a measuring container and a BL adapter is installed. The whole container was immersed in a thermostat and kept at 23 ° C., and the value one minute after the start was measured at 30 rpm.
[0030]
(Evaluation of storage stability)
The viscosity of the material immediately after preparation is defined as V1. Next, the viscosity of the material after immersion in a constant temperature bath at 40 ° C. for 7 days is defined as V2. When the value of V2 / V1 is 1.0 to 1.3 and the viscosity increase is small, the state is small, and when the viscosity increase exceeds 1.3, the state is large and the storage stability is evaluated in two stages. did.
[0031]
Example 1
A rotor coated with Teflon (registered trademark) was placed in a sample bottle (200 ml), and the rotor was placed on a magnetic stirrer. 4 g of DMM and 74 g of propylene glycol monomethyl ether acetate (PGMEA) were placed in a sample bottle. While stirring, 1.2 g of cardo epoxy resin: ESF-300 (manufactured by Nippon Steel Chemical Co., Ltd.), 11.4 g of phenol novolak type epoxy resin: Epicoat 154 (manufactured by Japan Epoxy Resin Co., Ltd.), alicyclic epoxy Resin: 11.4 g of EHPE-3150 (manufactured by Daicel Chemical Industries, Ltd.) was added and completely dissolved. Subsequently, after adding 5.3 g of trimellitic anhydride and sufficiently stirring and dissolving, 1 g of a silane coupling agent and 0.1 g of a surfactant were added and sufficiently stirred. This was filtered to obtain a material for a color filter protective film.
[0032]
Using the obtained composition for a protective film, a protective film was formed on a glass substrate in accordance with the evaluation method described above, and application unevenness was observed under a sodium lamp light source. Was evaluated. Table 1 shows the results. It is confirmed that the material for the protective film has excellent applicability.
[0033]
Example 2
The procedure was performed in the same manner as in Example 1 except that the amount of the solvent used was changed to 23 g of DMM and 55 g of PGMEA. Table 1 shows the results. It is confirmed that the composition for a protective film has excellent coatability.
[0034]
Example 3
The procedure was performed in the same manner as in Example 1 except that the amount of the solvent used was changed to 63 g of DMM and 16 g of PGMEA. Table 1 shows the results. It is confirmed that the composition for a protective film has excellent coatability.
[0035]
Example 4
The procedure was performed in the same manner as in Example 1 except that the solvent was a combination system of DMM and PGMEA and the composition was as shown in Table 1. Table 1 shows the results. Although the applicability is slightly inferior, it is confirmed that there is no problem in practicality.
[0036]
Comparative Example 1
An attempt was made to adjust the material for the protective film in the same manner as in Example 1 using only PGMEA as the solvent, but the epoxy resin did not completely dissolve despite sufficient stirring and dissolution at the time of dissolution of the epoxy resin. Therefore, no other components were added. Therefore, the intended material for the color filter protective film could not be obtained.
[0037]
Comparative Example 2
The procedure was performed in the same manner as in Example 1 except that DMM was not used as the solvent, and a combined system of PGMEA and propylene glycol monomethyl ether (PGME) was used. Table 1 shows the results. It is confirmed that the coating properties are inferior to those of the protective film composition described in the examples. It is also confirmed that the storage stability is poor.
[0038]
Comparative Example 3
The procedure was performed in the same manner as in Example 1 except that DMM was not used as a solvent, and a combined system of PGMEA and dipropylene glycol monomethyl ether acetate (DPMA) was used. Table 1 shows the results. It is confirmed that the coating property is inferior to the protective film composition of the example. It is also confirmed that the frame width is wide.
[0039]
[Table 1]
【The invention's effect】
The material for a color filter protective film of the present invention is excellent in coatability and storage stability, and the protective film for a color filter formed by using the material has no coating unevenness, and therefore has a flatness and a film thickness due to a narrow frame width. Excellent in uniformity.
Claims (4)
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| JP2002194272A (en) * | 2000-12-26 | 2002-07-10 | Nippon Steel Chem Co Ltd | Composition for color filter protective film and protective film |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7521100B2 (en) | 2003-04-08 | 2009-04-21 | Nippon Kayaku Kabushiki Kaisha | Liquid crystal sealing agent and liquid crystalline display cell using the same |
| JP2008058551A (en) * | 2006-08-31 | 2008-03-13 | Jsr Corp | Radiation-sensitive composition for colored layer formation and color filter |
| JP4656025B2 (en) * | 2006-08-31 | 2011-03-23 | Ｊｓｒ株式会社 | Radiation-sensitive composition for forming colored layer and color filter |
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| JP4536318B2 (en) | 2010-09-01 |
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