JP3747833B2 - Single-wafer coating method, color filter manufacturing method using the same, and color liquid crystal display device - Google Patents

Description

【００７５】
また、ポリイミド系樹脂には、イミド結合の他に、アミド結合、スルフォン結合、エーテル結合、カルボニル結合などのイミド結合以外の結合が含まれていても差し支えない。
【００７６】
上記一般式（１）中、Ｒ１は少なくとも２個以上の炭素原子を有する３価または４価の有機基である。耐熱性の面から、Ｒ１は環状炭化水素、芳香族環又は芳香族複素環を含有し、かつ炭素数６〜３０の３価または４価の基が好ましい。
【００７７】
Ｒ１の例として、フェニル基、ビフェニル基、ターフェニル基、ナフタレン基、ペリレン基、ジフェニルエーテル基、ジフェニルスルフォン基、ジフェニルプロパン基、ベンゾフェノン基、ビフェニルトリフルオロプロパン基、シクロブチル基、シクロペンチル基などが挙げられるが、これらに限定されない。
【００７８】
Ｒ２は少なくとも２個以上の炭素原子を有する２価の有機基であるが、耐熱性の面から、Ｒ２は環状炭化水素、芳香族環又は芳香族複素環を含有し、かつ炭素数６〜３０の２価の基が好ましい。Ｒ２の例として、フェニル基、ビフェニル基、ターフェニル基、ナフタレン基、ペリレン基、ジフェニルエーテル基、ジフェニルスルフォン基、ジフェニルプロパン基、ベンゾフェノン基、ビフェニルトリフルオロプロパン基、ジフェニルメタン基、ジシクロヘキシルメタン基などが挙げられるが、これらに限定されない。
【００７９】
前記一般式（１）を主成分とするポリマにおいては、Ｒ１、Ｒ２が上記したもののうち、各々１種類から構成されていても良いし、各々２種以上から構成される共重合体であってもよい。さらに、基板との接着性を向上させるために、耐熱性を低下させない範囲でジアミン成分として、シロキサン構造を有するビス（３−アミノプロピル）テトラメチルジシロキサンなどを共重合するのが好ましい。
【００８０】
前記一般式（１）を主成分とするポリマの具体的な例として、ピロメリット酸二無水物、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物、４，４’−オキシジフタル酸無水物、３，３’，４，４’−ビフェニルトリフルオロプロパンテトラカルボン酸二無水物、３，３’，４，４’−ビフェニルスルフォンテトラカルボン酸二無水物、２，３，５−トリカルボキシシクロペンチル酢酸二無水物などからなる群から選ばれた１種以上のカルボン酸二無水物と、パラフェニレンジアミン、３，３’−ジアミノジフェニルエーテル、４，４’−ジアミノジフェニルエーテル、３，４’−ジアミノジフェニルエーテル、３，３’−ジアミノジフェニルスルフォン、４，４’−ジアミノジフェニルスルフォン、４，４’−ジアミノジシクロヘキシルメタン、４，４’−ジアミノジフェニルメタン、４，４’−ジアミノベンズアニリドなどの群から選ばれた少なくとも１種以上のジアミンから合成されたポリイミド前駆体が挙げられるが、これらに限定されない。これらのポリイミド前駆体は公知の方法、すなわち、テトラカルボン酸二無水物とジアミンを選択的に組み合わせ、溶媒中で反応させることにより合成される。
【００８１】
本発明のカラーフィルタ用ペーストは、例えば、溶媒中に樹脂と着色剤または遮光剤を混合させた後、三本ロール、サンドグラインダー、ボールミル、サンドミル等の分散機中で分散させる方法などにより製造することができる。
【００８２】
次に、本発明のカラーフィルタ用ペーストを用いたカラーフィルタの製造方法について説明する。
【００８３】
すなわち、上記したカラーフィルタ用ペーストを使用してカラーフィルタの製造を行うものであり、具体的には透明基板上に、着色ペーストおよび／またはブラックペーストとして、上記したカラーフィルタ用ペーストを塗布することによりカラーフィルタを製造することができる。
【００８４】
以下、カラーフィルタの製造方法について例を挙げてさらに説明する。
【００８５】
本発明においてカラーフィルタは、透明基板上に３原色からなる着色層を複数配列したものであり、カラーフィルタは３原色からなる各着色層により形成された画素を一絵素とし、多数の絵素により構成されたものを意味する。
【００８６】
また３原色としては、加色混法によりカラー表示を行う場合には、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の３原色が選ばれ、減色混法によりカラー表示を行う場合には、シアン（Ｃ）、マゼンタ（Ｍ）、およびイエロー（Ｙ）の３原色が選ばれる。これらの３原色を含んだ要素を１単位としてカラー表示の絵素とすることができる。
【００８７】
透明基板としては、特に限定されるものでなく、石英ガラス、ホウケイ酸ガラス、アルミノケイ酸塩ガラス、表面をシリカコートしたソーダライムガラスなどの無機ガラス類、有機プラスチックのフィルムまたはシートなどが好ましく用いられる。
【００８８】
着色層は、例えば、着色ペーストを直接あるいはあらかじめブラックマトリックスを形成した透明基板上に塗布・乾燥した後に、パターニングを行うことにより形成することができる。
【００８９】
なお、ブラックペースト、着色ペーストを塗布する方法としては、先に述べたスピンコーティング法、ロールコーティング法、バーコーティング法、ダイコーティング法などを用いることができ、ダイコーティング法が好ましく挙げられるが、これらの方法に特に限定されない。なお、ダイコーティング法で用いられるダイ口金の詳細を図１０に示した。即ち、ダイ口金７は、長尺なブロック形状のリアリップ７１とフロントリップ７２の間に図示しないシムを挟みこみ、図示しない複数の連結ボルトで相互に一体的に結合して構成されている。ダイ口金７の内部では、その中央部分にマニホールド７３が形成されており、マニホールド７３は口金供給ホース７０に内部通路（図示しない）を介して常時接続されている。そして、マニホールド７３は、リアリップ７１、フロントリップ７２の間に挟みこんだシムと同じ厚さを持つスリット７４とつながっている。このスリット７４の下端は、吐出面７５にて開口して、塗液を吐出する吐出口７６になっている。そして塗液が吐出口７６から吐出されると、吐出面７５と被塗工材９との間にビードＣが形成される。被塗工材９はステージ８０に吸着保持され、任意の速度で往復動させることができる。
【００９０】
なお、本発明ではダイコータを例として説明したが、本発明の濾過装置は、スピンコータ、バーコータ、ロールコータ等すべての塗布装置にも好ましく適用することができる。
【００９１】
また、被塗工材９としてはガラス基板の他にアルミ等の金属板、セラミック板、シリコンウエハー等を用いても良い。
【００９２】
透明基板へペーストを塗布してウェット膜を形成した後、オーブンやホットプレートを用いて加熱乾燥（セミキュア）を行う。セミキュア条件は、使用する樹脂、溶媒、ペースト塗布量により異なるが６０〜２００℃で１〜６０分加熱することが好ましい。
【００９３】
このようにして得られたペースト塗膜は、樹脂が非感光性の樹脂である場合は、その上にポジ型フォトレジストの塗膜を形成した後に、また、樹脂が感光性の樹脂である場合は、そのままかあるいは酸素遮断膜を形成した後に、露光・現像を行い、樹脂ブラックマトリクス、着色層を形成することができる。必要に応じて、ポジ型フォトレジストまたは酸素遮断膜を除去し、再び、加熱乾燥（キュア）する。キュア条件は樹脂により異なるが、ポリイミド前駆体からポリイミド系樹脂を得る場合には、通常２００〜３００℃で１〜６０分加熱すればよい。
【００９４】
なお、着色層のキュア後膜厚は、要求される色特性と着色ペーストの着色剤／マトリックス樹脂比率により決定される。なお着色剤／マトリックス樹脂比率は重量比で５／９５〜７０／３０の範囲が好ましく、１０／９０〜６０／４０の範囲がより好ましい。着色剤比率が５未満の場合、十分な色純度を得るために塗布する必要のある膜厚が厚くなり、画素間の段差が大きくなり、液晶の配向不良などの弊害が発生することがある。着色剤比率が７０を超えると、マトリックス樹脂が不足するため画素の密着性が悪くなる傾向がある。着色剤／マトリックス樹脂比率が上記好ましい比率である場合、望ましい色特性を得るために塗布するキュア後膜厚を０．２〜４μｍとすることが好ましい。０．２μｍ以上とすることが色純度の点で好ましく、４μｍ以下とすることが光透過率の点で好ましい。
【００９５】
なおブラックマトリックスには、通常（２０〜２００）μｍ×（２０〜３００）μｍの開口部が設けられるが、この開口部を少なくとも被覆するように３原色からなる着色層が複数配列される。３原色のパターン配置は、モザイク型、トライアングル型、ストライプ型、４画素配置型など目的により、いずれも好適に用いることができる。
【００９６】
また、上記製造方法においては着色ペーストおよびブラックペーストの少なくとも一方に本発明の着色ペースト、ブラックペーストを用いればよく、着色ペーストとして本発明の着色ペーストを用いた場合は、ブラックマトリックスが、Ｃｒ、Ａｌ、Ｎｉなどの金属薄膜（厚さ約０．１〜０．２μｍ）やＣｒと透明基板間に酸化クロムや酸窒化クロム等の層を設けた多層クロム膜などの無機材料からなるものであってもよい。
【００９７】
なおブラックマトリックスの遮光性は、ＯＤ値（透過率の逆数の常用対数）で表されるが、液晶表示装置の表示品位を向上させるためには、好ましくは２．５以上であり、より好ましくは３以上である。ＯＤ値の上限は、ブラックマトリックスの膜厚により定められる。
【００９８】
本発明のブラックペーストを用いた樹脂ブラックマトリックスの場合、膜厚は、好ましくは０．５〜１．５μｍ、より好ましくは０．８〜１．２μｍである。膜厚が、０．５μｍよりも薄いと、遮光性の点で好ましくない。また、膜厚が１．５μｍよりも厚い場合は、遮光性は確保できるものの、カラーフィルタの平坦性が犠牲になり易く、段差が生じ易い。表面段差が生じた場合、カラーフィルタ上部に透明導電膜や液晶配向膜を形成させても段差は殆ど軽減されず、液晶配向膜のラビングによる配向処理が不均一になり、液晶表示装置の表示品位が低下する。表面段差を小さくするためには、着色層上に透明保護膜を設けることが有効である。
【００９９】
また、ブラックマトリックスの反射率は、画素と遮光領域の境界面における反射光による影響を低減し液晶表示装置の表示品位を向上させるために、４００〜７００ｎｍの可視領域での視感度補正された反射率（Ｙ値）で２％以下が好ましく、より好ましくは１％以下である。反射率が２％を越えると、表面反射光のために表示コントラストが低下する。
【０１００】
次に、本発明のカラーフィルタ用ペーストを用いて作成したカラー液晶表示装置について説明する。本発明において、カラー液晶表示装置は透明電極基板と透明電極を有するカラーフィルタにより液晶層を挟持したものであり、カラーフィルタが上記したカラーフィルタ用ペーストにより製造されたものであればよい。カラーフィルタには、必要に応じて着色層上に透明保護膜を設けても差し支えなく、また、カラーフィルタ上には透明電極としてＩＴＯ膜などを形成した上で透明電極基板を対向させる。
【０１０１】
カラーフィルタと対向する透明電極基板としては、ＩＴＯ膜などの透明電極が透明基板上にパターン化されて設けられ、さらに、透明電極基板に、透明電極以外に、薄膜トランジスタ（ＴＦＴ）素子や薄膜ダイオード（ＴＦＤ）素子、走査線、信号線などを目的に応じて設けることにより、ＴＦＴ液晶表示装置やＴＦＤ液晶表示装置を作製することができる。
【０１０２】
なお、カラー液晶表示装置は、透明電極を有するカラーフィルタおよび透明電極基板上に液晶配向膜を設け、ラビングなどによる配向処理が施され、次に、プラスチックビーズなどをスペーサーとして散布し、シール剤を用いてカラーフィルタおよび透明電極板を貼り合わせ、シール部に設けられた注入口から液晶を注入した後に、注入口を封止し、製造することができる。さらに、偏光板を基板の外側に貼り合わせた後にＩＣドライバーなどを実装することによりモジュールが完成する。
【０１０３】
上記した本発明のカラー液晶表示装置は、パソコン、ワードプロセッサ、エンジニアリング・ワークステーション、ナビゲーションシステム、液晶テレビ、ビデオなどの表示画面に用いられ、また、液晶プロジェクションなどにも好適に用いられる。
【０１０４】
なお、図２は図１と実質的な差がないため、説明を省略した。
【０１０５】
【実施例】
以下に、実施例を挙げて本発明をさらに詳しく説明するが、本発明はこれらに限定されるものではない。
【０１０６】
また、実施例中で使用されるポリイミド前駆体Ａ−１、オリゴアミック酸分散剤Ａ−２、カラーフィルタ用顔料分散赤ペーストは次の方法で製造されたものとする。
【０１０７】
Ａ．ポリイミド前駆体Ａ−１の製法
３，３’，４，４’−ビフェニルテトラカルボン酸二無水物、４，４’−ジアミノジフェニルエーテル、および、ビス（３−アミノプロピル）テトラメチルジシロキサンをγＢＬおよびＮＭＰの混合溶媒中で反応させ、ポリイミド前駆体Ａ−１の溶液を得た。
【０１０８】
Ｂ．オリゴアミック酸分散剤Ａ−２の製法
３，３’，４，４’−ジフェニルスルホンテトラカルボン酸二無水物、無水ピロメリット酸二無水物、３，３’−ジアミノジフェニルスルホン、および、ビス（３−アミノプロピル）テトラメチルジシロキサンをγＢＬ溶媒中で反応させた後、２−アミノアントラキノンで末端封止し、オリゴアミック酸分散剤Ａ−２の溶液を得た。
【０１０９】
Ｃ．カラーフィルタ用顔料分散Ｒペーストの製法
ホモジナイザー（日本精機製作所製）を用い、ガラスビーズ（東芝バロディーニ製ＧＢ７３７）を分散メディアとして、７０００ｒｐｍで３０分間攪拌し、顔料分散液を得た後、希釈し、以下の組成の着色ペースト（固形成分濃度５．１ｗｔ％）を得た。本赤ペーストの粘度は２３ｍＰａ・ｓであった。
【０１１０】
赤顔料１：Ｐｉｇｍｅｎｔ Ｒｅｄ ２５４ ０．８ｗｔ％
赤顔料２：Ｐｉｇｍｅｎｔ Ｒｅｄ １７７ ０．３ｗｔ％
黄顔料 ：Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １３８ ０．３ｗｔ％
分散剤 ：オリゴアミック酸Ａ−２ ０．１ｗｔ％
樹 脂 ：ポリイミド前駆体Ａ−１ ３．６ｗｔ％
溶 媒 ：ＮＭＰ、γＢＬ ９４．９ｗｔ％
実施例１〜４、比較例１〜３
図１に示すダイコーティング方式にて清浄なガラス基板（０．６２ｍ×０．７５ｍ）に上記Ｒペーストを１００枚塗布し、ポリマゲル状粒および顔料凝集粒の個数の推移を調べた。結果を表１に示す。
【０１１１】
【表１】

【０１１２】
注１） ＳＵＳ ： ＳＵＳ３１６
ＰＴＦＥ ： 四フッ化エチレン
注２） 樹脂はＪＩＳ Ｋ６９１１基づき測定した値、ＧＦおよびＳＵＳは引 っ張り試験機にて測定した値
注３） 塗布開始後１シート目の突起高さ１０μｍ以上のポリマーゲル状粒お よび顔料凝集異物の合計ををカウントした。
【０１１３】

【０１１４】

ヤング率が２００ＭＰａより小さい濾材を使用した比較例１〜３では、突起高さ１０μｍ以上のポリマーゲル状粒および顔料凝集粒の合計（表中では「凝集粒」と記載）が著しく多いため、これを研磨テープ等による公知の突起修正技術を用いて個々修正すると、修正に要する時間が長く必要となり、実質上カラーフィルタの生産歩留まりが低下する。また、このままカラーフィルタとして使用すると、対向する透明電極基板と凝集粒が接触して液晶表示素子の画素欠点となる。また、１００枚連続塗工における凝集粒の個数が明らかに増加傾向にあるため、フィルタの交換頻度を多くする必要がある。
【０１１５】
一方、ヤング率が２００ＭＰａ以上の濾材を使用した実施例１〜４では、凝集粒が少なく、研磨テープ等を用いた公知の突起修正技術により個々に修正可能である。特にステンレス焼結金属を用い、かつ、最も孔径の小さい濾材である実施例１においては凝集粒の発生は皆無であった。また、実施例１〜４では、１００枚連続塗工における凝集粒の増加傾向も見られず、フィルタの交換頻度も少なくて済む。
【０１１６】
実施例５
３６０×４６５ｍｍで厚さ０．７ｍｍの無アルカリガラス基板上に、基板の幅方向にピッチが４５６μｍ、基板の長手方向にピッチが１５２μｍ、線幅が３０μｍ、ＲＧＢ画素数が１９２０（基板長手方向）×４８０（基板幅方向）、全体の対角の長さが１４．４インチ（基板幅方向に２１９ｍｍ、基板長手方向に２９２ｍｍ）となる格子形状で、厚さが１μｍのブラックマトリックス膜を形成した。ブラックマトリックス膜は、チタン酸窒化物を遮光材、ポリアミック酸をバインダーとして用いたものであった。
【０１１７】
次いで、上流側スクリーン１４として開口率６０％で、開口部がφ０．５ｍｍの多数の孔で形成された厚みもの、下流側スクリーン１５として開口率９０％で、幅０．８ｍｍの線状物で図９に示すようにスコープ形状に形成された厚みもの、フィルタ１３として孔径４μｍで直径９０ｍｍの燒結金属フィルタを用い、さらに内部流路形状を流入口１９からフィルタ１３に向かって０．０７の割合で拡大し、フィルタ１３から流出口１９に向かって０．２２の割合で縮小する円鐘形状にした図４に示す濾過装置１０を用意した。この濾過装置１０を備えた図１に示すダイコータで、ポリアミック酸をバインダーとして、γ−ブチロラクトン、Ｎ−メチル−２−ピロリドンおよび３−メチル−３−メトキシブタノールの混合物を溶媒として、さらに、ピグメントレッド１７７を顔料にして固形分濃度１０％で混合し、さらに粘度を５０ｍＰａ・ｓに調整したＲペーストをバッファタンク２に充填し、定量供給ポンプ４で吐出速度８０００μｌ／ｓ、吐出時間３ｓ、吸引速度３０００μｌ／ｓ、吸引時間８ｓの送液条件でバッファタンク２からダイ口金７までエアーを排出しつつ、塗液の充填を行った。本条件では、エアーを完全に排出するには１０分間を要した。ここで、ダイ口金７にはスリット間隙１００μｍ、スリット幅２２０ｍｍのものを用いて、ウェット洗浄によってパーティクルを除去した基板上に、基板との間隙を１００μｍに設定して、塗布厚み２０μｍ、塗布速度３ｍ／ｍｉｎにて全面均一に塗布した。塗布された基板はホットプレートを使用した乾燥装置で１００℃で２０分乾燥した。続いて、固形分濃度１０％、粘度８％のレジスト液を１０μｍ塗布後、９０℃のホットプレートで１０分乾燥後、フォトマスクを用いて露光・現像・剥離をして、Ｒ画素部のみに塗膜を残し、２６０℃のホットプレートで３０分加熱して、キュアを行った。
【０１１８】
同様の色塗膜の形成をＧ、Ｂ色についても、Ｒ色と同様にダイコータを用いて、全面に均一な塗膜を形成後、所定格子状パターンに加工を行って色塗膜を形成した。ここでＧ色の塗布液には、Ｒ色の塗布液で顔料をピグメントグリーン３６にして固形分濃度１０％で粘度を４０ｍＰａ・ｓに調整したもの、Ｂ色の塗布液には、Ｒ色の塗布液で顔料をピグメントブルー１５にして固形分濃度１０％で粘度を５０ｍＰａ・ｓに調整したものを用いた。
【０１１９】
そして最後にＩＴＯをスパッタリングで蒸着させ、カラーフィルタを作成した。作成したカラーフィルタの膜厚と異物発生数を測定した結果、塗布開始部および終了部の膜厚不良領域は平均９．５ｍｍであった。また、粒子径４μｍ以上の異物発生数は平均３個／枚であった。
【０１２０】
比較例４
次に、濾過装置として従来の濾過装置３０を用いた以外は上記実施例と全く同じ条件でカラーフィルタを作成した。同様に作成したカラーフィルタの膜厚と異物発生数を測定した結果、塗布開始部および終了部の膜厚不良領域は平均１８ｍｍ、粒子径４μｍ以上の異物発生数は平均７個／枚であった。
【０１２１】
【発明の効果】
本発明では、ヤング率が２００ＭＰａ以上の濾材を使用したフィルタを具備することにより、被濾過液の供給が非定常的な工程を有する場合、特に枚葉塗工に必然となる塗液の間欠濾過における濾過圧力の急峻な変化に対して孔径の変化がなくなるため、所望の濾過精度を高く保つことができる。従って、塗液の製造工程から混入する環境異物、また、塗液がポリマー溶液である場合は、ポリマーゲルやモノマー残渣等の異物、塗液がスラリーである場合は粒子の凝集物等やバインダー樹脂（ポリマーまたはポリマー前駆体、感光性バインダーを用いる場合はその前駆体等）起因の異物を効果的に捕捉し、粒欠点のない高品位な膜面を得ることができる。
【０１２２】
また、本発明では、流入口からフィルタに向かって滑らかに拡大した形状、または、フィルタから流出口に向かって滑らかに縮小した形状の流路を有しているので、濾過装置内の滞留箇所を皆無にして、エアーを完全に排出することができる。さらに、フィルタの上下流側に開口率６０％以上のスクリーンを隣接して配置し、さらにフィルタの周囲にデッドスペースを実質上形成しない環状シール材を接して配置する構成を有していることにより、一層その効果を高めることができる。したがって、滞留による異物欠点がなく、残留エアーによって塗布開始・終了時の吐出応答性が妨げられないために塗布開始部および終了部の膜厚精度が高く、膜厚均一性に優れた高品質なカラーフィルタを高い生産性で製造することが可能となる。
【図面の簡単な説明】
【図１】ダイコータを使用した本発明の枚葉塗工の一実施例を示すフロー図である。
【図２】ダイコータを使用した本発明の枚葉塗工の他の実施例を示すフロー図である。
【図３】ダイコータを使用した本発明の枚葉塗工のさらに他の実施例を示すフローずである。
【図４】本発明の塗工装置に備えた濾過装置の一実施例を示す断面図である。
【図５】本発明の塗工装置に備えた濾過装置の他の実施例を示す断面図である。
【図６】従来の塗工装置に備えた濾過装置を示す断面図である。
【図７】図３の従来の濾過装置のシール部の拡大断面図である。
【図８】上流側スクリーンの一実施例を示す平面図である。
【図９】下流側スクリーンの一実施例を示す平面図である。
【図１０】ダイ口金部の断面略図である。
【符号の説明】
１：塗液タンク
２：バッファタンク
３：切替弁
４：定量供給ポンプ
５：切替弁
６：フィルタ
７：ダイ口金
８：ステージ
９：被塗工材
１０：濾過装置
１１：上流側ハウジング
１２：下流側ハウジング
１３：フィルタ
１４：上流側スクリーン
１５：下流側スクリーン
１６：環状パッキン
１７：デッドスペースを実質上形成しない環状シール材
１８：流入口
１９：流出口
２０：濾過装置
２１：上流側ハウジング
２２：下流側ハウジング
２８：流入口
２９：流出口
３０：従来の濾過装置
３１：上流側ハウジング
３２：下流側ハウジング
３７：Ｏリング
３８：流入口
３９：流出口
７０：口金供給ホース
７１：リアリップ
７２：フロントリップ
７３：マニホールド
７４：スリット
７５：吐出面
７６：吐出口
Ａ：滞留部
Ｂ：デッドスペース
Ｃ：ビード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus or method having a process in which the supply of liquid to be filtered is unsteady, and more particularly to a sheet-fed coating apparatus and a sheet-fed coating method, and more particularly in sheet-fed coating for precision coating. The present invention relates to a sheet-fed coating apparatus and a sheet-fed coating method that have improved the filtration of a coating liquid. In addition to forming a coating film on a substrate to create a color filter for a liquid crystal display, a liquid coating solution is intermittently applied to the surface of a material to be coated supplied in a single wafer mode. The present invention relates to a single-wafer coating apparatus, a single-wafer coating method, a color filter for a display device manufactured using the same, and a color display device, which are suitable for performing coating without any foreign matter defects caused by the coating liquid.
[0002]
[Prior art]
Conventionally, various substrates such as a plastic substrate for an optical filter, a glass substrate for a liquid crystal display, a glass substrate for a color filter, etc., which are relatively small substrates whose length in the coating direction is less than 2 m are used. There is a strong demand to apply the paint thinly and uniformly. In order to form a coating film on such a substrate industrially, a single-wafer coating method in which the material to be coated is supplied to the coater one by one, the coating material is supplied and applied, and transported to the next process such as drying. Will be adopted.
[0003]
Conventionally, spin coaters, roll coaters, bar coaters, die coaters, and the like, and combinations of these have been widely used as single wafer coating methods.
[0004]
The spin coating method is a method widely used for applying a photoresist on a semiconductor wafer, and forms a coating film by dropping a coating solution on the center of the surface of a rotating substrate. For color filter applications, for example, it is disclosed in JP-A-63-107769. The coating film obtained by the spin coating method is, for example, disclosed in Japanese Patent Application Laid-Open No. 6-348023 and Japanese Patent Application Laid-Open No. 7-261378, by changing the rheological properties of the coating liquid to Newtonian. Although the film thickness can be made uniform with high accuracy over a range, when the coating liquid is non-Newtonian or the viscosity is high, a thick film portion is generated at the center of rotation, and the film thickness uniformity is lowered. In addition, the amount of coating liquid used for obtaining a predetermined film thickness is remarkably large, which has an economic disadvantage.
[0005]
The roll coating method is a method of transferring a coating liquid to a substrate through a rubber roll, and can be applied to a long coated material or a rolled coated material. However, because the coating liquid is sequentially sent from the pan to the application roll and the substrate, it takes a long time for the coating liquid to be exposed to the air. .
[0006]
The bar coating method is a method in which a paste is applied to a substrate using a bar in which a thin wire is wound around a rod, and is disclosed in JP-A-2-258081. In this method, since the wire wound around the rod is in direct contact with the substrate, when the paste is non-Newtonian or the viscosity is high, the leveling property is poor and the wire trace remains.
[0007]
Depending on the coating liquid, the above coater is sufficient, but in recent years, it has been proposed to use a die coater. Further, proposals for applying a die coater to the production of a color filter are disclosed in Japanese Patent Laid-Open Nos. 5-11105, 5-142407, 6-339656, 8-229482, and 8-229497. This is done in the gazette.
[0008]
The die coater has been widely used for thick film coating and applications where a high viscosity paint is continuously applied. In the case of forming a coating film on a material to be coated using a die coater, US Pat. No. 4,230,793 is disclosed. , U.S. Pat. No. 4,696,885 and U.S. Pat. No. 2,761,791 are known coating methods such as curtain flow method, extrusion method and bead method. Normally, paint is discharged from a slit provided in the die coater die, and a paint reservoir called a paint bead is formed between the die and the workpiece to be moved relatively at a fixed interval. With the traveling of the material to be coated, the paint is drawn out to form a coating film. If the bead method is used in which the coating film is continuously formed by supplying the same amount of coating material consumed by the coating film formation from the slit, the formed coating film has a considerably uniform film thickness. High accuracy can be achieved. In addition, there is almost no waste of paint, and further, since the paint liquid supply path is sealed until it is discharged from the slit, it is possible to prevent paint deterioration and contamination, and to maintain high quality of the obtained coating film. .
[0009]
However, as described in detail in JP-A-8-229482 and JP-A-8-229497, the method using a die coater is very difficult to obtain a uniform coating film. If it is going to obtain a coating film, a coating apparatus will also become complicated. Accordingly, Japanese Patent Application Laid-Open No. 8-332436 proposes a single-wafer coating method for obtaining a uniform coating film by combining a simple linear coating method such as the above roll coater, bar coater or die coater with a spin coater.
[0010]
For example, when these single-wafer coating methods are applied to a color filter for a color liquid crystal display device, if there is a protrusion foreign matter defect in the coating film, the opposing substrate and the color filter substrate come into contact with each other and conduct a phenomenon called a common short. Display defects such as generation, bright spots and bright lines, black spots and black lines occur. In order to avoid such a situation, it is required that there is no protrusion foreign matter defect that causes a common short on the color filter substrate. In order to suppress protrusion foreign matter defects caused by the coating liquid in the coating film forming process, the following measures are usually taken. That is, in a series of single-wafer coating processes in which a material to be coated is supplied into the apparatus, a coating liquid is intermittently supplied and applied, and the material to be coated is transported to the next process such as drying. As shown in the Kaihei 8-229497 publication, in the path for intermittently supplying and applying the coating liquid to the material to be coated, the foreign matter contained in the coating liquid, that is, from the manufacturing process of the coating liquid When the coating liquid is a polymer solution or a polymer precursor solution, foreign substances such as polymer gel and monomer residue insoluble matter, and when the coating liquid is a slurry, particle agglomerates and binder resin ( In general, when a polymer, a polymer precursor, or a photosensitive binder is used, the resulting foreign matter is filtered and removed.
[0011]
Usually, as filters used for these filtrations, resin filter media such as polypropylene, polyethylene, and tetrafluoroethylene are used, and these are processed into a nonwoven fabric into a disk shape, or the nonwoven fabric is processed into a pleated shape or a roll. Examples of the membrane filter that have been processed into the shape of a capsule and the membrane filter that has been similarly made into a disk shape, a pleat shape, and a roll shape. In particular, a fluorine resin nonwoven fabric filter and a membrane filter are preferably used because of their good solvent resistance. In general, in the case of a polymer solution or polymer precursor solution that does not contain particles in the coating liquid, a membrane filter having a precise filtration accuracy of 0.05 to 3 μm, and in the case where particles are included in the coating liquid, it is coarse that causes a coating defect For the purpose of removing only particles, a non-woven fabric filter with optimized filtration accuracy according to the target particle diameter to be obtained is used. For example, when applying a slurry coating solution with a pigment dispersion color paste for a color filter and a pigment particle size of 0.1 μm or less in a film thickness of 2 μm, it is ideal to remove coarse particles of 2 μm or more. Thus, it is considered that the purpose of removing coarse particles can be achieved by using a nonwoven fabric filter having a pore diameter of 2 μm.
[0012]
In the single wafer coating apparatus, in order to reduce the frequency of intermittently filtering the coating liquid, as shown in FIG. 3, a buffer tank 2 is provided between the coating liquid tank 1 and the coating head (die base) 7, Although it is conceivable to perform filtration with the filter 6 in front of the buffer tank 2, as described in Japanese Patent Application Laid-Open No. 11-319675, the filter 6 is installed immediately before the coating head (die base) 7. It is preferable from the viewpoint of suppressing foreign matter defects, and even if a filter 6 is installed in front of the metering pump (metering pump) 4, it is more effective in suppressing foreign matter defects, but a resin filter medium filter having a low Young's modulus is used. In such a configuration, only the number of filtrations is reduced, and essentially coarse particle trapping by filtration and coating due to the dispersion / crushing effect of the polymer gel, pigment aggregate and their mixture described later are performed. Not a foreign substance defect suppression of time.
[0013]
Various shapes of the filter are used as described above. In order to form a uniform film surface, the void volume inside the filter is particularly small, and the ejection responsiveness at the time of sheet coating is good. A filter device in which a disk-like filter is sandwiched between two upstream and downstream housings and a pair of annular packings are disposed between the housings is preferably used, as shown in Japanese Patent Laid-Open No. 5-208. The filtration device has an inlet for coating liquid in the upstream housing, and the coating liquid supplied from the inlet is filtered by the filter and discharged from the outlet through the outlet provided in the downstream housing. The
[0014]
However, in such a filtering device, the coating liquid tends to stay at the ends of the upstream and downstream housings. In particular, if it stays in the downstream housing for a long time, the coating liquid deteriorates, and foreign matter generated due to the deterioration is supplied to the coating apparatus together with the filtered coating liquid and applied to the substrate, so there is a defect in the coating surface. There is a problem that it occurs.
[0015]
In addition, when performing single wafer coating using a die coater, a large pressure fluctuation occurs particularly at the start and end of coating because the coating liquid is intermittently supplied and filtered for each substrate. If air remains in the coating liquid flow path, the remaining air expands and contracts due to pressure fluctuations that occur each time the substrate is applied. As a result, the defective film thickness region of the product increases. In order to prevent this, a so-called air bleed operation in which the air from the coating solution supply tank to the die is completely discharged and filled with the coating solution is essential before coating. Actually, it is difficult to completely discharge the air in the filtration device. Especially in the coating liquid having a viscosity of 100 mPa · s or less, a large amount of air remains on the upstream side of the filter, and the discharge starts and ends. Experiments have shown that the film thickness at the time becomes unstable.
[0016]
As a method for removing the air remaining in the filtering device, it is common to provide an air vent outlet in the housing of the filtering device as described in JP-A-11-28323. However, when a discharge port is provided in the filtration device, the coating liquid stays in the vicinity of the discharge port, and foreign matter is generated in the coating liquid that is easily deteriorated.
[0017]
[Problems to be solved by the invention]
The present invention is intended to eliminate the disadvantages of the prior art, and the object of the present invention is that it has a good foreign matter capturing performance such as polymer gel and particle aggregates in the coating liquid as described above, and will be described later. The dispersion / crushing effect of polymer gels, pigment aggregates, and their mixtures eliminates the defect of foreign matter application due to the coating liquid, and minimizes the residual air inside the filtration device, resulting in high quality with high film thickness uniformity. An object of the present invention is to provide a single wafer coating apparatus capable of obtaining a film surface.
[0018]
Another object of the present invention is to produce a color filter using such a sheet coating apparatus, a color display device using the color filter, a sheet coating method, a color filter using the same, and a color display. To provide a device.
[0019]
[Means for Solving the Problems]
  The object of the present invention is as follows [1] to [8This is basically achieved by the configuration described in the above.
[1] 100 g / s · m of pigment dispersion²A single-wafer coating method for intermittently supplying to a coating head while filtering at the above filtration speed, and using a sintered metal filter having a hole diameter of 0.05 μm or more and 100 μm or less upstream from the coating head Equipped with a filtering deviceThen, a pressure gauge and a valve are installed in this order on the downstream side of the filtration device, the valve is closed and liquid is fed to increase the internal pressure of the filtration device, and the pressure detected by the pressure gauge reaches a set value. By releasing the valve at the time, the remaining air inside the filtration device is discharged and discharged.A sheet coating method characterized by that.
[2] In a filtration apparatus using a sintered metal filter, the flow path has a shape enlarged from the inlet to the filter and / or a shape reduced from the filter to the outlet, and the enlarged The single-wafer coating method according to claim 1, further comprising a filtration device having a reduction ratio satisfying the formula (1) and / or (2).
0.025 ≦ h_IN/ (D_FLT-D_IN) ≦ 1 (1)
0.1 ≦ h_OUT/ (D_FLT-D_OUT) ≦ 1 (2)
    d_IN: Inlet diameter [mm]
    d_OUT: Outlet diameter [mm]
    d_FLT: Diameter [mm] actually used for filtration in the filter
    h_IN: Distance from the inlet to the filter [mm]
    h_OUT: Distance from outlet to filter [mm]
[3] The single-wafer coating method according to any one of [1] or [2], wherein a screen having an aperture ratio of 60% or more is disposed adjacent to the downstream side of the filter.
[4] The single wafer coating method according to any one of claims 1 to 3, wherein a screen having an aperture ratio of 60% or more is disposed adjacent to the upstream side of the filter.
[5] The single-wafer coating method according to any one of [1] to [4], wherein an annular sealing material that does not substantially form a dead space is disposed around the filter.
[6] The single wafer coating method according to any one of [1] to [5], wherein the coating is performed using a pigment dispersion having a viscosity of 100,000 mPa · s or less.
[7] [1]-[6] The manufacturing method of the color filter characterized by using the sheet | seat coating method in any one of.
[8] [7A color liquid crystal display device using the color filter obtained by the method for producing a color filter according to claim 1.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0027]
In the present invention, to supply the coating liquid unsteadyly means, for example, that the supply speed and / or supply pressure of the coating liquid frequently fluctuate (especially in the filter portion). The fluctuation in this case refers to a decrease in the liquid feeding speed or pressure due to the temporary stop of the operation such as coating or the transition to the next process with respect to the normal state where the coating liquid is supplied downstream and the operation such as coating is performed. It has at least two states of fluctuation state. The effect of the present invention is preferably exhibited when the supply speed ratio (fluctuating supply speed / normal supply speed) is 80% or less (more preferably 50% or less, more preferably 20% or less). Or the supply pressure ratio (fluctuated supply pressure / normal supply pressure) is 80% or less (more preferably 50% or less, more preferably 20% or less). This is a case where the range fluctuates. The effect of the present invention is preferably exhibited when the fluctuation cycle is in the range of 600 seconds or less (more preferably 300 seconds or less, more preferably 60 seconds or less), or This is a case where the fluctuation cycle is repeated 50 times or more (more preferably 250 times or more, more preferably 500 times or more) without adjustment such as filter replacement in the middle. The simple case is when the supply rate is 0, which corresponds to the case of sheet coating. In the case of sheet-fed coating, unless a buffer tank is provided between the filter unit and the coating unit, the coating liquid supply speed in the filter unit requires a sequence that substantially stops. Note that the single-wafer coating method or apparatus in the present invention may be any method or apparatus as long as it is a method or apparatus for applying the coating materials one by one as described above, and the above-described spin coating method, roll coating method, bar coating method. In addition to the die coating method, a spray coating method, a nozzle coating method, or the like may be used. Also, the distinction between continuous coating and single-wafer coating is that the former cuts the unsteady part until the coating film reaches the steady coating state, and then uses only the steady part continuously. On the other hand, the latter distinguishes all the parts from the initial stage of coating to the end of coating as a single member. The present invention relates to the latter sheet-fed coating method and apparatus. Hereinafter, the sheet coater of the die coater will be described as an example, but the sheet coater is not limited to this.
[0028]
FIG. 1 is a conceptual diagram showing an example of single-wafer coating according to the present invention, and shows a flow from a coating solution tank to a die die. The coating liquid is fed from the coating liquid tank 1 to the buffer tank 2 provided downstream of the coating liquid tank 1 by pressure feeding. Next, the switching valve 3 provided downstream of the buffer tank 2 is opened, and at the same time, suction of a syringe pump (quantitative supply pump) 4 provided downstream of the switching valve 3 is started to suck the coating liquid. The suction amount Q (g) of the coating liquid with the syringe pump 4 is the area S (m of the coating film to be coated on the material to be coated.²), Film thickness t (μm), and solid component concentration c (wt%) of the coating liquid. The specific gravity of the coating film is ρ (g / cm^Three) Is theoretically obtained as follows.
[0029]
Q = S · t × 10^-6・ Ρ × 10⁶/ C x 10²
After the coating liquid is sucked in a predetermined amount, the switching valve 3 is closed, and at the same time, the switching valve 5 provided downstream of the syringe pump 4 is opened, and the syringe pump 4 starts feeding liquid. By this operation, a pool of coating liquid is formed between the material to be coated on the stage 8 and the die base 7, and then the stage 8 is moved relative to the die base 7 to form a coating film. Since the time T (S) during which the coating liquid is discharged from the die die 7 to the material to be coated is uniquely determined from the request for the takt time, the liquid feeding speed v (g / s) of the syringe pump 4 Is obtained as follows.
[0030]
v = Q / T
Here, the filtration area of the filter 6 is S_f(M²), Filtration rate v_f(G / s · m^Three) Is calculated as follows.
[0031]
v_f= V / S_f
When the movement of the stage 8 reaches the end point of the material to be coated, the switching valve 5 is closed and the single-wafer coating is finished.
[0032]
The present invention is characterized in that a filter medium having a Young's modulus of 200 MPa or more is used in a single wafer coating apparatus provided with a filter 6 on the upstream side of the die base 7.
[0033]
Even when coating is performed using a single-wafer coating apparatus equipped with a filter with optimized filtration accuracy, if the filter medium is a resin, that is, a soft filter with a low Young's modulus, Coarse polymer gels and coarse aggregates of particles cannot be completely filtered, and these foreign substances are applied as they are on the material to be coated, which is a coating defect. This mechanism is explained as follows.
[0034]
Consider the single-wafer coating of the above-mentioned pigment dispersed color paste for color filters. Sheets in which pigment particles of 0.1 μm or less are dispersed in a photosensitive polymer precursor solution or a non-photosensitive polymer solution as a binder, the above-described spin coater, roll coater, bar coater, die coater, or the like, or a combination of these Application is performed with a leaf coating apparatus. In this single wafer coating device, the coating head from the coating liquid supply tank to the final coating of the material to be coated (the name varies depending on the coating device. For example, in the case of a spin coater, in the case of a discharge nozzle, die coater In this case, even if filtration is performed using a resin filter medium nonwoven fabric filter that captures coarse particles of 2 μm or larger, the coating solution is intermittently supplied because of the single-wafer coating method. The pore size of the filtered resin non-woven fabric filter is 2 μm or more due to pressure fluctuation at each supply and filtration, and the pigment aggregate or pigment-dispersed color paste solidified product, polymer gel, photosensitive polymer precursor insoluble matter exceeding 2 μm It is thought that coarse particles such as spill out cause coating defects.
[0035]
According to this consideration, it can be considered that the present invention is suitably applied even when the same filtration step is used outside the coating field.
When a filter medium having a Young's modulus of less than 200 MPa is used, the pore diameter of the filter changes due to steep filtration pressure fluctuations during intermittent liquid feeding, and the desired filtration accuracy cannot be obtained. When the coating liquid is a polymer solution, foreign matter such as polymer gel or monomer residue, when the coating liquid is a slurry, particle agglomerates, etc. and binder resin (polymer or polymer precursor, when using a photosensitive binder) The foreign matter resulting from the precursor or the like is not captured, resulting in a coating defect. The Young's modulus of the filter medium is more preferably 500 MPa or more, and even more preferably 1000 MPa or more. By using a filter medium with a high Young's modulus, foreign matter is captured without changing the filter pore diameter due to steep filtration pressure fluctuations during intermittent liquid feeding, and dispersion of polymer gels, pigment aggregates, and mixtures thereof described later / By the crushing effect, it is possible to obtain a high-quality coating film with no foreign matter defects. Moreover, the same effect can be expected even when a polymer gel is generated in an abnormal retention portion inside the filter. The higher the Young's modulus of the filter medium is, the better.
[0036]
As described in Note 2 of Table 1, the Young's modulus of the filter medium is a method based on JIS K6911 for resins, a method based on JIS R1602 for ceramics, and a general material for metals and other materials. Measure with a tensile tester used for the test.
[0037]
Examples of the material having such a Young's modulus and usable as a filter medium include, but are not limited to, glass fiber, porous ceramic, sintered metal and the like. Sintered metal is preferred because it has no alkali metal elution, is generally available, and is inexpensive. As the metal material, it is preferable to use stainless steel in terms of rust prevention. Sintered metal filters include those obtained by sintering a fibrous metal and those obtained by sintering a powdered metal, either of which may be used.
[0038]
In addition, when the coating liquid contains charged particles such as a pigment dispersion, aggregation of the particles occurs due to an increase in the charge amount due to friction when the filter medium and the charged particles are fed within the filter medium layer. A conductive metallic filter that has a function of discharging the gas, particularly a sintered metal filter, is effective.
[0039]
In the present invention, it is preferable that the filter has a certain level of performance from the viewpoint of structural mechanical properties, along with the Young's modulus, which is a material mechanical property, and the width and / or thickness of the lattice constituting the filter. Is preferably in the range of 0.05 μm to 100 μm (more preferably 0.05 μm to 5 μm, even more preferably 0.2 μm to 20 μm, particularly preferably 0.5 μm to 10 μm). If the value falls below the lower limit of the numerical range, the filter lattice may be deformed or cut, which is not preferable. On the other hand, when the value exceeds the upper limit of the numerical range, there are problems such as a decrease in filtration efficiency and difficulty in maintaining fine pore diameter accuracy. In addition, a plurality of lattice layers having a diameter in the numerical range may be laminated, preferably 5 layers or more (more preferably 10 layers or more, and further preferably 20 layers or more). The upper limit of the number of layers is not particularly limited, but if it is too large, there is a problem such as an increase in filtration resistance, and this is greatly influenced by the filter pore diameter described later, so that the upper limit cannot be generally defined. As a lamination method, for example, when the material is a metal, a single layer composed of fine wires oriented in one direction or randomly is stacked, applied with appropriate pressure, and further sintered as necessary, so that the intersection is plastic. What is necessary is just to make it deform | transform and fix.
[0040]
Moreover, about a filter hole diameter, it is preferable to use the filter of 0.05 micrometer or more and 100 micrometers or less. If a filter having a pore diameter of less than 0.05 μm is used, the filter pressure loss becomes excessively high and liquid feeding becomes difficult, and if a filter having a pore diameter of more than 100 μm is used, foreign matter to be trapped will be undesirably passed. In the case of a polymer solution or a polymer precursor solution that does not contain particles in the coating liquid, the smaller the pore diameter is, the more preferable it is 0.05 μm or more and 5 μm or less. In the case where particles are included in the coating liquid, it is preferable to optimize the filtration accuracy in accordance with the target particle diameter to be obtained for the purpose of removing only coarse particles that are a coating defect. For example, in the case of a pigment-dispersed color paste for a color filter, since the particle diameter of the pigment is 0.1 μm or less, it is preferably 0.2 μm or more and 20 μm, more preferably 0.5 μm or more and 10 μm or less.
[0041]
The filter pore diameter is a pore diameter obtained from measurement by a bubble point described in JIS K3832.
[0042]
The coating liquid suitable for the present invention may be any of a polymer solution or polymer precursor solution that does not contain particles in the coating liquid, and a slurry that contains particles in the coating liquid. In the former case, foreign matter such as polymer gel and monomer residue insoluble matter, in the latter case, foreign matter caused by particle aggregates and binder resin (polymer or polymer precursor, precursor when photosensitive binder is used) It can be removed by filtration, and a high-quality film surface can be obtained.
[0043]
The viscosity of the coating liquid is preferably 100,000 mPa · s or less, and more preferably 10,000 mPa · s or less. If it is greater than 100,000 mPa · s, the pressure loss during filtration increases and it becomes difficult to pass through the filter. Further, if the pressure loss becomes excessive, the desired filter pore diameter changes, which is not preferable.
[0044]
The viscosity is measured with an E-type viscometer (cone rotational viscometer) in a low viscosity region smaller than 1200 mPa · s, and with a B-type viscometer (cylinder rotary viscometer) in a higher viscosity region. .
[0045]
The filtration rate is 100 g / s · m.²The above is preferable. Although details are unknown, it has been surprisingly confirmed that there is a dispersion / crushing effect of gels and particle aggregates, especially when a hard filter with a high Young's modulus is used. For expression, preferably 200 g / s · m²Or more, more preferably 300 g / s · m²That's it. In the case of the die coating method, the filtration rate can be obtained by the above-described calculation formula.
[0046]
In the case of a resin disk-shaped filter, the pressure resistance as a filter is low because of its material and shape, and the filter is not used unless a pressure plate (usually a perforated plate, hereinafter referred to as a screen in the present invention) is used on the back of the filter. Therefore, depending on the configuration of the single wafer coating apparatus to be applied, it is necessary to use a screen. Also in this case, in the filter medium having a Young's modulus of 200 MPa or less, the filter is compressed on the screen, the coating liquid is abnormally retained inside the filter, and the coating liquid is solidified inside the filter. The coating liquid is a polymer precursor solution. In this case, foreign matters such as polymer gel and monomer residue insoluble matter are generated. When the coating liquid is a slurry, agglomerates of particles and binder resin (polymer or polymer precursor, precursor when a photosensitive binder is used) Etc.) Detrimental effects such as occurrence of foreign matter are generated. Therefore, even when a screen is used for a disk-shaped filter, the Young's modulus of the filter medium is preferably 200 MPa or more. In addition, if a filter having a Young's modulus of the filter medium of preferably 1000 MPa or more is used, a screen is unnecessary on the back of the filter, even if it is a disk-shaped filter, and abnormal retention of the coating liquid at the filter-screen interface can be suppressed. As a result, it is possible to suppress the generation of foreign matter due to abnormal retention as described above.
[0047]
The coating apparatus provided with a filtration device using a disk-shaped filter will be further described in detail. FIG. 4 is a cross-sectional view showing an embodiment of the filtration device provided in the coating apparatus of the present invention having a linear flow path, and FIG. 5 shows another embodiment of the filtration apparatus of the present invention having a curved flow path. FIG. 6 is a sectional view showing a conventional filtration device, FIG. 7 is an enlarged sectional view showing a seal portion of the conventional filtration device, and FIG. 8 is a plan view showing one embodiment of the upstream screen. 9 is a plan view showing an embodiment of the downstream screen.
[0048]
FIG. 4 shows a filtration device 10 provided in the coating apparatus according to the present invention. In the filtering device 10, an annular sealing material 17 that does not substantially form a dead space is disposed around a disk-shaped filter 13 that captures foreign matters in the coating liquid, and is sandwiched between the upstream screen 14 and the downstream screen 15. A product is sandwiched between an upstream housing 11 and a downstream housing 12 via an annular packing 16. Here, since the upstream screen 14 and the downstream screen 15 have a role of supporting the filter 13 and must pass the coating liquid freely, a large number of holes are formed in a metal disk as shown in FIG. The one provided with is usually used. Although FIG. 8 is a plan view showing an embodiment of the upstream screen, it may be used for the downstream screen in some cases. Conversely, the same applies to FIG. 9, that is, the screen shown in FIG. 9 may be used as the downstream screen. In FIG. 4, the coating liquid is supplied from an inlet 18 provided in the upstream housing 11, passes through a flow path that expands in a conical shape toward the filter 13, is filtered by the filter 13, and then downstream. To the outlet 19 provided in the side housing 12, it passes through a flow path that is reduced to a conical shape and is discharged. The filtering device 10 is fixed by a bracket (not shown) so that the coating liquid flows upward and is filtered with the outlet 19 facing upward.
[0049]
FIG. 6 shows a conventional filtration device 30. The filtering device 10 according to the present invention is an annular sealing material in which the internal flow paths of the upstream housing 31 and the downstream housing 32 have a cylindrical shape with no enlargement / reduction, and a dead space is not substantially formed around the filter 13. 17 except that the downstream screen 15 and the downstream housing 32 are sealed with an O-ring 37 instead of the annular packing 16, and the upstream screen 14 and the downstream screen 15 are the same. Are the same. FIG. 7 shows in more detail a situation where sealing is performed by sandwiching the upstream screen 14, the filter 13, and the downstream screen 15 between the O-ring 37 and the annular packing 16 in the filtration device 30. In the conventional filtration device 30, a dead space B is generated around the filter 13 due to its configuration. However, in the illustrated filtration device 10 according to the embodiment of the present invention, such a dead space B does not occur.
[0050]
The filtration device 10 provided in the coating device of the present invention has an effect of reducing the retention due to its configuration as compared with the conventional filtration device 30. Next, it will be described.
[0051]
First, like the filtration device 10 (or 20) shown in FIG. 4 (or 5), in the present invention, the flow path of the coating liquid formed inside the upstream housing 11 (or 21) is connected to the inlet 18 (or 28) from the filter 4 to the filter 13 and / or the flow path of the downstream housing 12 (or 22) smoothly from the filter 4 to the outlet 19 (or 29) Have. The ratio of enlargement / reduction needs to satisfy the formula (1) and / or (2).
[0052]
0.025 ≦ h_IN/ (D_FLT-D_IN) ≦ 1 (1)
0.1 ≦ h_OUT/ (D_FLT-D_OUT) ≦ 1 (2)
d_IN: Inlet diameter [mm]
d_OUT: Outlet diameter [mm]
d_FLT: Diameter [mm] actually used for filtration in the filter 13
h_IN: Distance from inlet 18 to filter 13 [mm]
h_OUT: Distance from outlet 19 to filter 13 [mm]
As used herein, the flow path refers to a structure, an inner wall, or a conduit that regulates the flow of a processing fluid (coating liquid, unfiltered liquid, filtered liquid, etc.). In this case, the inner wall of the housing may be considered. Here, the diameter actually used for filtration in the filter 13 corresponds to the diameter of the effective area of the filter in filtration. For example, even if the diameter of the filter itself is large, if the flow path of the coating liquid is obstructed by the annular packing or the annular sealing material, the diameter actually used for the filtration is reduced accordingly. 4 and 5, the diameter of the portion of the filter not covered with the annular packing is the diameter actually used for filtration. In addition, the filtration device of the present invention has a vertical cross section (meaning a cross section cut along a plane perpendicular to the upstream-downstream direction) approximately circular (in this case, the diameter is the diameter of the circle). Although it is preferable, it may be an ellipse or other closed curve depending on the case. In this case, the diameter (inlet / outlet diameter, diameter actually used in the filter, etc.) is the diameter of the circle when the vertical cross section is converted into a circle in an equal area. In addition,
Position a: Junction between the inlet and the upstream housing
Position b: Surface upstream of the filter
Position c: Surface on the downstream side of the filter
Position d: Joint portion of downstream housing, outlet and housing
Then, h_INAnd h_OUTAre the distances between positions ab and cd measured in the direction of fluid flow in the filtration device (may be the major axis direction of the filtration device or the filter thickness direction), respectively. . When the flow path of the coating liquid is formed in such a shape, there is no place (residence place) where almost no flow occurs like the stay part A at the end of the housing of the conventional filter device 30. Residence can be greatly reduced. The ratio of enlargement / reduction needs to be 1 or less (preferably 0.3 or less), and if it is larger than this, the internal flow passage capacity increases, so the coating liquid in the filtration device 10 is replaced with a new coating liquid. The time required for complete replacement increases, which is undesirable. The ratio of enlargement / reduction must be 0.025 or more (preferably 0.1 or more, more preferably 0.15 or more) on the upstream side, and 0.1 or more (preferably 0.15 or more) on the downstream side. If it is smaller than this, it is not preferable because the coating liquid is difficult to flow uniformly in the flow path. The effect of reducing stagnation by this flow path shape has also been confirmed from the verification of the flow by visualization. Further, another filtration device 20 of the present invention shown in FIG. 5 is a filtration device except that the flow paths of the upstream housing 21 and the downstream housing 22 are not conical, but are a combination of a conical shape and a rounded surface. 10 is the same as the filter device 10 except that there is substantially no portion where no flow occurs, and therefore, there is almost no retention.
[0053]
In the present invention, being smooth means having substantially no dead space. The dead space here is a portion of the housing where gas or coating liquid tends to stay. As a specific example, in the cross section of FIGS. 4 and 5 ((cross section cut along a plane parallel to the upstream-downstream direction), one corner (including one having an R of 3 mm or less) is sandwiched 2 Even if there is such a dead space, the angle between the two wall surfaces measured from the inside of the housing is 150 to 180 ° (more preferably 170 to 180 °) or two wall surfaces. If the length of the wall surface starting from the corner between the two is 1 μm or less (more preferably 0.1 μm or less), it may be considered that there is substantially no dead space.
[0054]
In the present invention, it is preferable that at least one of the upstream or downstream flow paths has a smooth expanded shape or a smoothly reduced shape as described above. Of course, it is preferable that the upstream and downstream flow paths have a smooth shape as described above. However, only one of them is effective, and in that case, considering that foreign substances generated due to stagnation can be filtered, only the downstream channel is smoothly reduced rather than only the upstream channel having a smoothly enlarged shape. It is preferable to have such a shape.
[0055]
In addition, the shape of the filter used in the present invention is not particularly limited, and examples thereof include a polygonal shape, an elliptical shape, and other curved shapes. It is preferable that In addition, in FIGS. 4-7, as already shown, the example of a disk-shaped filter is given.
[0056]
Further, the aperture ratio of the downstream screen 15 disposed adjacent to the downstream side of the disk-shaped filter 13 of the filtration device 10 is preferably 60% or more, more preferably 85% or more. When the aperture ratio is within the above range, the contact area for supporting the filter 13 to which pressure is applied is minimized, so that the occurrence of stagnation at the contact surface between the filter 13 and the downstream screen 15 is prevented. Can do. When the opening ratio is less than 60%, the coating liquid tends to stay on the contact surface. In order to increase the aperture ratio and reduce the contact area, it is preferable to form the downstream screen 15 with a linear object having a width of 1 mm or less as shown in FIG.
[0057]
In addition, when it is difficult to execute an appropriate air venting method, the aperture ratio of the upstream screen 14 disposed adjacent to the disk-shaped filter 13 is preferably 10 to 50%, more preferably 15 to 30%, and preferably about 95% or less for the downstream screen. When the aperture ratio is within the above range, the air pressure remaining on the upstream side of the disk-shaped filter 13 can increase the filtration pressure through which the filter 13 passes, so that the air can easily pass through the filter 13 and the outlet. 19 can be discharged. As described above, when it is difficult to execute an appropriate air venting method, the upstream screen 14 may be a disc-shaped plate member provided with a number of holes as shown in FIG. The diameter of the hole is preferably φ3 mm or less, more preferably φ0.5 to 1 mm. However, as long as the aperture ratio is satisfied, the hole may be formed into a linear shape as shown in FIG.
[0058]
Next, the filtration device 10 provided in the coating device of the present invention can easily vent the air or prevent the intrusion of air from the outside because of its configuration, compared to the conventional filtration device 30. The reason will be explained below.
[0059]
In the filtering device 10, the annular sealing material 17 that does not substantially form a dead space is disposed around the filter 13, so that the dead space B that is an air remaining portion in the conventional filtering device 30 as shown in FIG. In other words, the air in the dead space B can be prevented from entering the filter 13. Further, when a sintered metal filter is used as the filter 13, the annular sealing material 17 that does not substantially form a dead space is eliminated, and the periphery of the filter 13 is pressed to eliminate the air gap. Here, the annular sealing material that does not substantially form a dead space is a material that closely contacts the annular sealing material and other members (housing, screen, filter) that do not form a gap. For that purpose, the said annular sealing material needs to have a shape suitable for the space shape in which it is inserted, and to have moderate elasticity. In particular, it is important to have elasticity in order to absorb the filter size error in the radial direction. Also, in the radial direction, the inner diameter side surface of the annular seal member is preferably 2 to 5 mm on the outer peripheral side than the inner wall side surface of the annular packing. If the value is below the numerical range, a part of the fluid from the upstream may pass through without passing through the filter. If the value exceeds the numerical value range, air may remain on the outer periphery of the annular seal material, which may be undesirable. is there.
[0060]
Moreover, since the flow path of the downstream housing 12 is smoothly reduced upward from the filter 13 toward the outlet 19, the air that has passed through the filter 13 is filtered by the buoyancy of the filtering device 10. And can be easily discharged out of the filtration device 10.
[0061]
With the above configuration, since air is easily discharged and no air enters from the outside, no air remains in the filtration device, so the discharge response at the start and end of application with large pressure fluctuations It is not hindered by the residual air, it becomes good, and a high-quality film surface with a uniform film thickness can be obtained.
[0062]
Furthermore, in order to efficiently discharge the air, the inventor of the present invention installed a pressure gauge and a valve in this order on the downstream side of the filtration device, closed the valve and sent the coating liquid to reduce the internal pressure of the filtration device. It was newly discovered that it is extremely effective to discharge the residual air inside the filtration device by raising the pressure and rapidly opening the valve when the pressure detected by the pressure gauge reaches the set value. This will be specifically described with reference to FIG. A pressure gauge and a valve are installed between the filter 6 and the die base 7 in this order, and the valve is closed as described above to feed the coating liquid. When the pressure detected by the pressure gauge reaches a specified value, the valve is suddenly released, and the remaining air remaining in the filter 6 is discharged together with the coating liquid. At this time, it is preferable to automatically release the valve in conjunction with the pressure gauge, but it may be performed manually while looking at the pressure gauge. If it is carried out automatically, it becomes easy to carry out the air discharge operation a plurality of times while the fixed supply pump 4 performs a single discharge. At this time, after the air discharge operation is performed once while the metering pump 4 discharges the coating liquid, if the time from closing the valve again to entering the air discharge operation standby is set as short as possible, one discharge is in progress. In addition, a large number of the air discharge operations can be carried out, and the time required for air venting can be shortened. In order to suppress the generation of foreign matter due to abnormal stagnation after the filter 6, it is preferable to remove the pressure gauge and valve from between the filter 6 and the die base 7 after the air venting is completed.
[0063]
The upstream screen 14 and the downstream screen 15 are preferably made of stainless steel in terms of rigidity and rust prevention. However, when a filter having high rigidity such as a sintered metal filter is used as the filter 13, the downstream screen 15 may not be provided.
[0064]
As the shape of the annular sealing material 17 which does not substantially form a dead space, it is preferable that the cross section is square from the viewpoint of adhesion to the housing, and the material is a red which is excellent in chemical resistance and hardly swells. Silicon, Teflon (registered trademark) and the like are preferable.
[0065]
Examples of the filter 13 that can be used include polypropylene, polyethylene, tetrafluoroethylene, glass fiber and other woven fabrics / nonwoven fabrics, porous ceramics, sintered metals, etc. Other than these may be used. Most preferred is stainless sintered metal as described above.
[0066]
In particular, a case where the present invention is applied to a pigment-dispersed color paste for a color filter will be described in detail below.
[0067]
As the colorant, organic pigments, inorganic pigments, and the like can be used, and it is desirable to use organic pigments in terms of chromaticity characteristics, heat resistance, chemical resistance, light resistance, and the like. Furthermore, you may add various additives, such as a ultraviolet absorber, a dispersing agent, and a leveling agent. In particular, in order to improve the dispersion stability of the pigment and lower the yield value, it is desirable to add a dispersion stabilizer.
[0068]
In black paste, a mixture of red, blue and green pigments as well as metal oxide powder such as carbon black, titanium oxide, titanium oxynitride and iron tetroxide, metal sulfide powder and metal powder as a light-shielding agent. Etc. can be used. Among these, carbon black is particularly preferable because of its excellent light shielding properties. Since carbon black having a small particle size and excellent dispersibility mainly exhibits a brown color tone, it is preferable to mix a complementary color pigment with respect to the carbon black to make it achromatic. In addition, it is preferable to use titanium oxynitride in a black paste for a color filter used in a liquid crystal display device driven by an electric field parallel to the substrate in order to increase the volume resistance value of the black matrix. To these black pastes, various additives such as an ultraviolet absorber, a dispersant, and a leveling agent may be added as in the case of the colored paste. In particular, it is desirable to add a dispersion stabilizer in order to improve the dispersion stability of the light shielding agent and lower the yield value.
[0069]
The matrix resin used for the paste is not particularly limited, and is a photosensitive or non-photosensitive material such as epoxy resin, acrylic resin, urethane resin, polyester resin, polyimide resin, polyolefin resin, and gelatin. Are preferably used, and it is preferable to disperse or dissolve a colorant or a light-shielding agent in these resins for coloring.
[0070]
Photosensitive resins include photodegradable resins, photocrosslinkable resins, and photopolymerizable resins. In particular, monomers, oligomers, or polymers having an ethylenically unsaturated bond and initiators that generate radicals by ultraviolet rays are used. A photosensitive composition containing, a photosensitive polyamic acid composition, and the like are preferably used.
[0071]
As the non-photosensitive resin, those that can be developed with the above-mentioned various polymers are preferably used, but they are heat resistant to withstand the heat applied in the transparent conductive film forming process and the liquid crystal display manufacturing process. In addition, since a resin having resistance to an organic solvent used in a manufacturing process of a liquid crystal display device is preferable, a polyimide resin and an acrylic resin are particularly preferably used.
[0072]
When the matrix resin is a polyimide resin, examples of the solvent include amide polar solvents such as N-methyl-2-pyrrolidone (hereinafter referred to as NMP), N, N-dimethylacetamide, N, N-dimethylformamide, γ- A lactone polar solvent such as butyrolactone (hereinafter referred to as γBL) is preferably used.
[0073]
Although it does not specifically limit as a polyimide-type resin, Usually, the polyimide precursor (n = 1-2) which has a structural unit represented by following General formula (1) as a main component is heated or imidized by a suitable catalyst. What was used is used suitably.
[0074]
[Chemical 1]

[0075]
The polyimide resin may contain bonds other than imide bonds such as amide bonds, sulfone bonds, ether bonds, and carbonyl bonds in addition to imide bonds.
[0076]
In the above general formula (1), R1 is a trivalent or tetravalent organic group having at least two carbon atoms. From the viewpoint of heat resistance, R1 preferably contains a cyclic hydrocarbon, an aromatic ring or an aromatic heterocyclic ring, and is a trivalent or tetravalent group having 6 to 30 carbon atoms.
[0077]
Examples of R1 include phenyl group, biphenyl group, terphenyl group, naphthalene group, perylene group, diphenyl ether group, diphenyl sulfone group, diphenylpropane group, benzophenone group, biphenyltrifluoropropane group, cyclobutyl group, cyclopentyl group and the like. However, it is not limited to these.
[0078]
R2 is a divalent organic group having at least 2 carbon atoms. From the viewpoint of heat resistance, R2 contains a cyclic hydrocarbon, an aromatic ring or an aromatic heterocycle, and has 6 to 30 carbon atoms. These divalent groups are preferred. Examples of R2 include phenyl group, biphenyl group, terphenyl group, naphthalene group, perylene group, diphenyl ether group, diphenylsulfone group, diphenylpropane group, benzophenone group, biphenyltrifluoropropane group, diphenylmethane group, dicyclohexylmethane group and the like. However, it is not limited to these.
[0079]
In the polymer having the general formula (1) as a main component, R1 and R2 may be composed of one kind each of those described above, or may be composed of two or more kinds each. Also good. Furthermore, in order to improve the adhesion to the substrate, it is preferable to copolymerize bis (3-aminopropyl) tetramethyldisiloxane having a siloxane structure as a diamine component within a range that does not lower the heat resistance.
[0080]
Specific examples of the polymer having the general formula (1) as a main component include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-oxydiphthalate. Acid anhydride, 3,3 ′, 4,4′-biphenyltrifluoropropanetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 2,3,5- One or more carboxylic acid dianhydrides selected from the group consisting of tricarboxycyclopentylacetic acid dianhydride, paraphenylenediamine, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,4 ′ -Diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodisi B hexyl methane, 4,4'-diaminodiphenylmethane, 4,4'-but-diamino benzanilide polyimide precursors synthesized from at least one or more diamines selected from the group including but are not limited thereto. These polyimide precursors are synthesized by a known method, that is, by selectively combining tetracarboxylic dianhydride and diamine and reacting them in a solvent.
[0081]
The paste for a color filter of the present invention is produced by, for example, a method in which a resin and a colorant or a light-shielding agent are mixed in a solvent and then dispersed in a dispersing machine such as a triple roll, sand grinder, ball mill, or sand mill. be able to.
[0082]
Next, a method for producing a color filter using the color filter paste of the present invention will be described.
[0083]
That is, a color filter is manufactured using the above-described color filter paste. Specifically, the above-described color filter paste is applied as a colored paste and / or a black paste on a transparent substrate. Thus, a color filter can be manufactured.
[0084]
Hereinafter, the manufacturing method of the color filter will be further described with examples.
[0085]
In the present invention, the color filter has a plurality of colored layers composed of three primary colors arranged on a transparent substrate, and the color filter has a pixel formed by each colored layer composed of the three primary colors as one picture element, and a large number of picture elements. Means that.
[0086]
As the three primary colors, when performing color display by additive color mixing, the three primary colors of red (R), green (G), and blue (B) are selected, and when performing color display by subtractive color mixing. The three primary colors of cyan (C), magenta (M), and yellow (Y) are selected. An element including these three primary colors can be used as a unit to form a picture element for color display.
[0087]
The transparent substrate is not particularly limited, and inorganic glass such as quartz glass, borosilicate glass, aluminosilicate glass, soda lime glass whose surface is silica-coated, organic plastic film or sheet is preferably used. .
[0088]
The colored layer can be formed, for example, by patterning directly or after applying and drying a colored paste on a transparent substrate on which a black matrix is previously formed.
[0089]
In addition, as a method of applying the black paste and the colored paste, the spin coating method, the roll coating method, the bar coating method, the die coating method and the like described above can be used, and the die coating method is preferably mentioned. The method is not particularly limited. Details of the die die used in the die coating method are shown in FIG. That is, the die base 7 is configured by sandwiching a shim (not shown) between a long block-shaped rear lip 71 and a front lip 72 and integrally connecting them with a plurality of connecting bolts (not shown). Inside the die base 7, a manifold 73 is formed at the center thereof, and the manifold 73 is always connected to the base supply hose 70 via an internal passage (not shown). The manifold 73 is connected to a slit 74 having the same thickness as a shim sandwiched between the rear lip 71 and the front lip 72. The lower end of the slit 74 is opened at the discharge surface 75 and serves as a discharge port 76 for discharging the coating liquid. When the coating liquid is discharged from the discharge port 76, a bead C is formed between the discharge surface 75 and the material 9 to be coated. The material 9 to be coated is held by suction on the stage 80 and can be reciprocated at an arbitrary speed.
[0090]
In the present invention, the die coater has been described as an example. However, the filtration apparatus of the present invention can be preferably applied to all coating apparatuses such as a spin coater, a bar coater, and a roll coater.
[0091]
In addition to the glass substrate, the material 9 to be coated may be a metal plate such as aluminum, a ceramic plate, a silicon wafer, or the like.
[0092]
After applying a paste to a transparent substrate to form a wet film, heat drying (semi-cure) is performed using an oven or a hot plate. Semi-cure conditions vary depending on the resin, solvent, and paste application amount to be used, but heating at 60 to 200 ° C. for 1 to 60 minutes is preferable.
[0093]
When the resin paste is a non-photosensitive resin, the paste coating obtained in this way is used after a positive photoresist coating is formed thereon, and when the resin is a photosensitive resin. The resin black matrix and the colored layer can be formed by performing exposure and development as they are or after forming an oxygen blocking film. If necessary, the positive type photoresist or the oxygen blocking film is removed, and then heat-dried (cured) again. The curing conditions vary depending on the resin, but when a polyimide resin is obtained from the polyimide precursor, it is usually heated at 200 to 300 ° C. for 1 to 60 minutes.
[0094]
The post-cure film thickness of the colored layer is determined by the required color characteristics and the colorant / matrix resin ratio of the colored paste. The colorant / matrix resin ratio is preferably in the range of 5/95 to 70/30 by weight, and more preferably in the range of 10/90 to 60/40. When the colorant ratio is less than 5, the film thickness that needs to be applied in order to obtain sufficient color purity is increased, the level difference between the pixels is increased, and adverse effects such as poor alignment of liquid crystals may occur. If the colorant ratio exceeds 70, the matrix resin is insufficient and the pixel adhesion tends to deteriorate. When the colorant / matrix resin ratio is the above-described preferable ratio, it is preferable that the post-cure film thickness to be applied is 0.2 to 4 μm in order to obtain desirable color characteristics. A thickness of 0.2 μm or more is preferable in terms of color purity, and a thickness of 4 μm or less is preferable in terms of light transmittance.
[0095]
The black matrix is usually provided with an opening of (20 to 200) μm × (20 to 300) μm, and a plurality of colored layers of three primary colors are arranged so as to cover at least the opening. The pattern arrangement of the three primary colors can be suitably used according to the purpose such as mosaic type, triangle type, stripe type, and four pixel arrangement type.
[0096]
In the above production method, the colored paste and the black paste of the present invention may be used for at least one of the colored paste and the black paste. When the colored paste of the present invention is used as the colored paste, the black matrix is Cr, Al. It is made of an inorganic material such as a metal thin film (thickness of about 0.1 to 0.2 μm) such as Ni or a multilayer chromium film in which a layer of chromium oxide or chromium oxynitride is provided between Cr and a transparent substrate. Also good.
[0097]
The light blocking property of the black matrix is represented by an OD value (common logarithm of the reciprocal of the transmittance), and is preferably 2.5 or more, more preferably, in order to improve the display quality of the liquid crystal display device. 3 or more. The upper limit of the OD value is determined by the film thickness of the black matrix.
[0098]
In the case of the resin black matrix using the black paste of the present invention, the film thickness is preferably 0.5 to 1.5 μm, more preferably 0.8 to 1.2 μm. If the film thickness is thinner than 0.5 μm, it is not preferable in terms of light shielding properties. On the other hand, when the film thickness is thicker than 1.5 μm, the light shielding property can be secured, but the flatness of the color filter is likely to be sacrificed and a step is likely to occur. When a surface step occurs, even if a transparent conductive film or liquid crystal alignment film is formed on the color filter, the step is hardly reduced, and the alignment treatment by rubbing the liquid crystal alignment film becomes non-uniform, and the display quality of the liquid crystal display device Decreases. In order to reduce the surface level difference, it is effective to provide a transparent protective film on the colored layer.
[0099]
Further, the reflectance of the black matrix is a reflection-corrected reflection in the visible region of 400 to 700 nm in order to reduce the influence of the reflected light at the boundary surface between the pixel and the light shielding region and improve the display quality of the liquid crystal display device. The rate (Y value) is preferably 2% or less, more preferably 1% or less. If the reflectivity exceeds 2%, the display contrast decreases due to the surface reflected light.
[0100]
Next, a color liquid crystal display device prepared using the color filter paste of the present invention will be described. In the present invention, the color liquid crystal display device has a liquid crystal layer sandwiched between a transparent electrode substrate and a color filter having a transparent electrode, and any color filter may be used as long as it is manufactured from the above-described color filter paste. If necessary, the color filter may be provided with a transparent protective film on the colored layer. Further, an ITO film or the like is formed as a transparent electrode on the color filter, and the transparent electrode substrate is opposed to the color filter.
[0101]
As a transparent electrode substrate facing the color filter, a transparent electrode such as an ITO film is patterned on the transparent substrate. Further, in addition to the transparent electrode, a thin film transistor (TFT) element or a thin film diode ( A TFT liquid crystal display device or a TFD liquid crystal display device can be manufactured by providing a TFD element, a scanning line, a signal line, or the like according to the purpose.
[0102]
The color liquid crystal display device is provided with a liquid crystal alignment film on a color filter having a transparent electrode and a transparent electrode substrate, and subjected to an alignment treatment by rubbing or the like. The color filter and the transparent electrode plate are bonded to each other, and after injecting liquid crystal from the injection port provided in the seal portion, the injection port can be sealed and manufactured. Furthermore, the module is completed by mounting an IC driver or the like after the polarizing plate is bonded to the outside of the substrate.
[0103]
The above-described color liquid crystal display device of the present invention is used for display screens of personal computers, word processors, engineering workstations, navigation systems, liquid crystal televisions, videos, etc., and is also preferably used for liquid crystal projections.
[0104]
Note that FIG. 2 is not substantially different from FIG.
[0105]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
[0106]
In addition, the polyimide precursor A-1, the oligoamic acid dispersant A-2, and the pigment-dispersed red paste for color filter used in the examples are manufactured by the following method.
[0107]
A. Method for producing polyimide precursor A-1
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 4,4′-diaminodiphenyl ether, and bis (3-aminopropyl) tetramethyldisiloxane are reacted in a mixed solvent of γBL and NMP. A solution of polyimide precursor A-1 was obtained.
[0108]
B. Method for producing oligoamic acid dispersant A-2
3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3′-diaminodiphenylsulfone, and bis (3-aminopropyl) tetramethyldisiloxane After reacting in a γBL solvent, the end-capping was performed with 2-aminoanthraquinone to obtain a solution of oligoamic acid dispersant A-2.
[0109]
C. Manufacturing method of pigment dispersion R paste for color filter
Using a homogenizer (manufactured by Nippon Seiki Seisakusho), glass beads (GB737 manufactured by Toshiba Barodini) as a dispersion medium, stirring at 7000 rpm for 30 minutes to obtain a pigment dispersion, diluting, and coloring paste (solid component) of the following composition A concentration of 5.1 wt%) was obtained. The viscosity of the red paste was 23 mPa · s.
[0110]
    Red pigment 1: Pigment Red 254 0.8 wt%
    Red pigment 2: Pigment Red 177 0.3 wt%
    Yellow pigment: Pigment Yellow 138 0.3 wt%
    Dispersant: Oligoamic acid A-2 0.1 wt%
    Resin: Polyimide precursor A-1 3.6 wt%
    Solvent: NMP, γBL 94.9 wt%
  Example 14Comparative Examples 1 to 3
  100 sheets of the R paste were applied to a clean glass substrate (0.62 m × 0.75 m) by the die coating method shown in FIG. 1, and the transition of the number of polymer gel particles and pigment aggregated particles was examined. The results are shown in Table 1.
[0111]
[Table 1]

[0112]
  Note 1)  SUS: SUS316
          PTFE: Tetrafluoroethylene
  Note 2) Resin values measured according to JIS K6911, GF and SUS values measured with a tensile tester
  Note 3) After the start of coating, the total of polymer gel-like particles having a protrusion height of 10 μm or more and pigment-aggregated foreign matter on the first sheet was counted.
[0113]

[0114]

In Comparative Examples 1 to 3 using a filter medium having a Young's modulus of less than 200 MPa, the total of polymer gel particles and pigment aggregated particles having a protrusion height of 10 μm or more (described as “aggregated particles” in the table) is remarkably large. If the individual correction is performed using a known protrusion correction technique using a polishing tape or the like, a long time is required for correction, and the production yield of the color filter is substantially reduced. If it is used as it is as a color filter, the opposing transparent electrode substrate and aggregated particles come into contact with each other, resulting in a pixel defect of the liquid crystal display element. Further, since the number of aggregated particles in the 100-sheet continuous coating is clearly increasing, it is necessary to increase the replacement frequency of the filter.
[0115]
  On the other hand, Examples 1 to 10 using a filter medium having a Young's modulus of 200 MPa or more.4Then, there are few agglomerated grains and they can be individually corrected by a known protrusion correction technique using an abrasive tape or the like. Examples using stainless steel sintered metal and the smallest pore size filter medium1There was no occurrence of agglomerated grains. Examples 1 to4Then, there is no tendency to increase the aggregated particles in the continuous coating of 100 sheets, and the replacement frequency of the filter can be reduced.
[0116]
  Example5
  On a non-alkali glass substrate of 360 × 465 mm and a thickness of 0.7 mm, the pitch is 456 μm in the substrate width direction, the pitch is 152 μm in the longitudinal direction of the substrate, the line width is 30 μm, and the number of RGB pixels is 1920 (substrate longitudinal direction). A black matrix film having a lattice shape of × 480 (substrate width direction) and an overall diagonal length of 14.4 inches (219 mm in the substrate width direction and 292 mm in the substrate longitudinal direction) and a thickness of 1 μm was formed. . The black matrix film was obtained using titanium oxynitride as a light shielding material and polyamic acid as a binder.
[0117]
Next, the upstream screen 14 has an opening ratio of 60% and the opening is formed by a large number of holes having a diameter of 0.5 mm, and the downstream screen 15 is a linear object having an opening ratio of 90% and a width of 0.8 mm. As shown in FIG. 9, a sintered metal filter having a thickness formed in a scope shape and a filter 13 having a hole diameter of 4 μm and a diameter of 90 mm is used, and the internal flow path shape is a ratio of 0.07 from the inlet 19 toward the filter 13. The filter device 10 shown in FIG. 4 was prepared in the shape of a bell that was enlarged at a rate of 0.22 toward the outlet 19 from the filter 13 and reduced at a rate of 0.22. In the die coater shown in FIG. 1 equipped with the filtration device 10, a polyamic acid is used as a binder, a mixture of γ-butyrolactone, N-methyl-2-pyrrolidone and 3-methyl-3-methoxybutanol is used as a solvent, and pigment red is further used. 177 is used as a pigment and mixed at a solid content concentration of 10%, and further R paste whose viscosity is adjusted to 50 mPa · s is filled in the buffer tank 2 and discharged at a constant feed pump 4 at a discharge speed of 8000 μl / s, a discharge time of 3 s, and a suction speed. The coating liquid was filled while discharging air from the buffer tank 2 to the die die 7 under a liquid feeding condition of 3000 μl / s and a suction time of 8 s. Under these conditions, it took 10 minutes to completely discharge the air. Here, a die base 7 having a slit gap of 100 μm and a slit width of 220 mm is used. On the substrate from which particles have been removed by wet cleaning, the gap with the substrate is set to 100 μm, the coating thickness is 20 μm, and the coating speed is 3 m. The entire surface was uniformly applied at / min. The coated substrate was dried at 100 ° C. for 20 minutes with a drying apparatus using a hot plate. Subsequently, after applying 10 μm of a resist solution having a solid content concentration of 10% and a viscosity of 8%, drying on a hot plate at 90 ° C. for 10 minutes, exposure, development and peeling using a photomask are performed only on the R pixel portion. The coating was left and cured by heating on a hot plate at 260 ° C. for 30 minutes.
[0118]
For the G and B colors, the same color coating was formed using a die coater in the same way as for the R color, and after forming a uniform coating on the entire surface, it was processed into a predetermined lattice pattern to form a color coating. . Here, the G-color coating liquid is an R-color coating liquid with pigment green 36 adjusted to a solid content concentration of 10% and a viscosity of 40 mPa · s, and the B-color coating liquid has an R-color coating liquid. The coating liquid was Pigment Blue 15 and the viscosity was adjusted to 50 mPa · s at a solid content concentration of 10%.
[0119]
Finally, ITO was deposited by sputtering to create a color filter. As a result of measuring the film thickness of the color filter and the number of foreign matters generated, the film thickness defect area at the coating start and end portions was an average of 9.5 mm. The number of foreign matters having a particle diameter of 4 μm or more was 3 / sheet on average.
[0120]
Comparative Example 4
Next, a color filter was prepared under exactly the same conditions as in the above example except that the conventional filtration device 30 was used as the filtration device. As a result of measuring the film thickness and the number of foreign matters generated in the same color filter, the average thickness of defective areas at the coating start and end portions was 18 mm, and the number of foreign matters having a particle diameter of 4 μm or more was average 7 pieces / sheet. .
[0121]
【The invention's effect】
In the present invention, by providing a filter using a filter medium having a Young's modulus of 200 MPa or more, when the supply of the liquid to be filtered has an unsteady process, intermittent filtration of the coating liquid, which is inevitably necessary for sheet-fed coating, in particular. Since the pore diameter does not change with respect to the steep change in filtration pressure at, the desired filtration accuracy can be kept high. Therefore, environmental foreign matter mixed from the manufacturing process of the coating liquid, and when the coating liquid is a polymer solution, foreign substances such as polymer gel and monomer residue, and when the coating liquid is a slurry, aggregates of particles and binder resin It is possible to effectively capture foreign substances due to (a polymer, a polymer precursor, a precursor when a photosensitive binder is used), and obtain a high-quality film surface free from grain defects.
[0122]
Further, in the present invention, since the flow path has a shape that is smoothly enlarged from the inlet to the filter, or a shape that is smoothly reduced from the filter to the outlet, The air can be exhausted completely without any. Furthermore, by having a configuration in which screens having an aperture ratio of 60% or more are disposed adjacent to the upstream and downstream sides of the filter, and an annular seal material that does not substantially form a dead space is disposed around the filter. The effect can be further enhanced. Therefore, there is no foreign matter defect due to stagnation, and discharge responsiveness at the start and end of coating is not hindered by residual air, so the coating thickness at the start and end of coating is high, and high quality with excellent film thickness uniformity. A color filter can be manufactured with high productivity.
[Brief description of the drawings]
FIG. 1 is a flowchart showing one embodiment of a single wafer coating of the present invention using a die coater.
FIG. 2 is a flowchart showing another embodiment of the single-wafer coating of the present invention using a die coater.
FIG. 3 is a flowchart showing still another embodiment of the single-wafer coating of the present invention using a die coater.
FIG. 4 is a cross-sectional view showing an embodiment of a filtration device provided in the coating apparatus of the present invention.
FIG. 5 is a cross-sectional view showing another embodiment of the filtration device provided in the coating apparatus of the present invention.
FIG. 6 is a cross-sectional view showing a filtration device provided in a conventional coating apparatus.
7 is an enlarged cross-sectional view of a seal portion of the conventional filtration device of FIG.
FIG. 8 is a plan view showing an embodiment of the upstream screen.
FIG. 9 is a plan view showing an embodiment of the downstream screen.
FIG. 10 is a schematic cross-sectional view of a die base portion.
[Explanation of symbols]
1: Coating liquid tank
2: Buffer tank
3: Switching valve
4: Metering pump
5: Switching valve
6: Filter
7: Die base
8: Stage
9: Material to be coated
10: Filtration device
11: Upstream housing
12: Downstream housing
13: Filter
14: Upstream screen
15: Downstream screen
16: Annular packing
17: Annular sealing material that does not substantially form dead space
18: Inlet
19: Outlet
20: Filtration device
21: Upstream housing
22: Downstream housing
28: Inlet
29: Outlet
30: Conventional filtration device
31: Upstream housing
32: Downstream housing
37: O-ring
38: Inlet
39: Outlet
70: Base supply hose
71: Rear lip
72: Front lip
73: Manifold
74: Slit
75: Discharge surface
76: Discharge port
A: Retention part
B: Dead space
C: Bead

Claims (8)

A single-wafer coating method in which a pigment dispersion is intermittently supplied to a coating head while being filtered at a filtration rate of 100 g / s · m ² or more, and the pore diameter is 0.05 μm upstream from the coating head. A filtration device using a sintered metal filter of 100 μm or less is provided , and a pressure gauge and a valve are installed in this order on the downstream side of the filtration device, and the valve is closed to send liquid to control the internal pressure of the filtration device. The single-wafer coating method is characterized in that when the pressure detected by the pressure gauge reaches a set value, the valve is released to discharge and discharge the remaining air inside the filtering device . In the filtration apparatus using the sintered metal filter, the flow path has a shape enlarged from the inlet to the filter and / or a shape reduced from the filter to the outlet, and / or the enlarged and / or The single-wafer coating method according to claim 1, further comprising a filtration device having a reduction ratio satisfying the formula (1) and / or (2).
0.025 ≦ h _IN / (d _FLT −d _IN ) ≦ 1 (1)
0.1 ≦ h _OUT / (d _FLT −d _OUT ) ≦ 1 (2)
d _IN : Inlet diameter [mm]
d _OUT : _Outlet diameter [mm]
d _FLT : Diameter actually used for filtration by the filter [mm]
h _IN : Distance from the inlet to the filter [mm]
h _OUT : Distance from outlet to filter [mm] 3. The single wafer coating method according to claim 1, wherein a screen having an aperture ratio of 60% or more is disposed adjacent to the downstream side of the filter. The single wafer coating method according to any one of claims 1 to 3, wherein a screen having an aperture ratio of 60% or more is disposed adjacent to the upstream side of the filter. The single-wafer coating method according to any one of claims 1 to 4, wherein an annular sealing material that substantially does not form a dead space is disposed around the filter. The single wafer coating method according to any one of claims 1 to 5, wherein the coating is performed using a pigment dispersion having a viscosity of 100,000 mPa · s or less . Method of manufacturing a color filter, which comprises using a sheet coating method according to any one of claims 1-6. A color liquid crystal display device using a color filter obtained by the method for producing a color filter according to claim 7 .

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