JP4631242B2

JP4631242B2 - Coating film drying method and apparatus

Info

Publication number: JP4631242B2
Application number: JP2001297402A
Authority: JP
Inventors: 和宏沖
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2001-09-27
Filing date: 2001-09-27
Publication date: 2011-02-16
Anticipated expiration: 2021-09-27
Also published as: JP2003093952A

Description

【０００１】
【発明の属する技術分野】
本発明は、塗布膜の乾燥方法および装置に係り、特に、連続走行する帯状可撓性支持体に各種液状組成物を塗布して形成した長尺で広幅な塗布膜面を乾燥する乾燥方法および装置に関する。
【０００２】
この技術は、光学補償シート等の光学的機能性フイルムシート、感光材料用のフイルムの溶剤下塗り、熱現像感光材料、ナノ粒子等の微細構造粒子を含む機能性フイルム、写真用フィルム、写真用印画紙、磁気記録テープ、接着テープ、感圧記録紙、オフセット版材、電池、等の製造、等に使用される。
【０００３】
【従来の技術】
連続走行する帯状可撓性支持体に各種液状組成物を塗布して形成した長尺で広幅な塗布膜面を乾燥する乾燥方法および装置については、E.B.Gutoff、E.D.Cohen 著の『Coating and Drying Defects』(Wiley-Intersciece, John Wiley & Sons, Inc) に非塗布面側をロールで支持し、塗布面側にエア・ノズルから風を吹いて乾燥させる乾燥方法や、塗布面、非塗布面ともにエア・ノズルから風を吹いて、支持体を浮上させた状態、すなわち支持体がロール等に接触しないで乾燥させる非接触式のエア・フローティング乾燥方法について記されている。この非接触式の乾燥方法については、スペースを効率良く利用し、かつ効率良く乾燥させる方法として特公昭48-42903に開示されているような弦巻き型の乾燥装置を用いた乾燥方法等がある。
【０００４】
通常これらの風を吹かせて乾燥させる方法( 以下、通風乾燥方法という) では、調湿した風を塗布面に吹きつけることにより、塗布面中に含まれる溶媒を蒸発させて乾燥させている。この通風乾燥方法は乾燥効率に優れるものの、塗布面に直接または多孔板、整流板等を介して風をあてるために、この風によって塗布面が乱れて塗布層の厚さが不均一となってムラを生じたり、対流によって塗布面での溶媒の蒸発速度が不均一になったりし、いわゆるユズ肌( 尾崎勇次著、『コーティング工学』、pp293 〜294 、朝倉書店、1971年、参照) 等が発生して、均一な塗布層が得られないという問題があった。
【０００５】
特に、塗布液中に有機溶剤を含む場合には、このようなムラの発生は顕著である。この理由は、乾燥初期には塗布膜中に有機溶剤が十分に含まれた状態であり、この段階で有機溶剤の蒸発分布が生じると、その結果、塗布膜面に温度分布、表面張力分布を生じ、塗布膜面内で、いわゆるマランゴニー対流等の流動が起きることによる。このようなムラの発生は重大な塗布欠陥となる。
【０００６】
塗布膜内に液晶を含む場合には、上記の乾燥ムラのみならず、吹きつける風によって塗布膜面の液晶の配向にズレが生じる等の問題もあった。
【０００７】
これらの問題点を解決する方法として、特開2001-170547 に塗布直後に乾燥ドライヤを設ける構成が示されている。ここでは、乾燥ドライヤを分割し、分割された部分に支持体の幅方向の一方端側から他方端側へ風速を制御しながら送風し乾燥させることにより、ムラの発生を抑える方法が開示されている。特開平9-73016 には、同様の目的で乾燥ドライヤを分割するかわりに金網を設置する方法が開示されている。
【０００８】
また特開2001-170547 には、塗布液を高濃度化したり、塗布液に増粘剤を添加したりすることにより、塗布液の粘度を増加させ、これにより塗布直後の塗布膜面の乾燥風による流動を抑制する方法や、高沸点溶液を用いることにより、塗布直後の塗膜面の乾燥風による流動が発生してもレベリング効果によってムラの発生を防止する方法が開示されている。
【０００９】
しかしながら、特開2001-170547 、特開平9-73016 の方法では、乾燥ドライヤ外からの不均一な風の流入抑止には効果があるものの、塗布膜面を乱さないように風速を制御しようとすると、風速を大きく下げる必要がある。その結果、乾燥速度が大幅に低下し、それに対処するべく乾燥ドライヤの長さを長くする必要がある。そのため、塗布効率が悪くなる。また、それでも風の影響を完全になくすことは困難である。
【００１０】
また、塗布液を増粘させたり、高沸点溶液を使用する方法は、特開2001-170547 で述べられているように、高速塗布適性をなくしたり、乾燥時間の増大をもたらしたりし、生産効率が極端に悪くなるという問題があった。
【００１１】
このように、通風乾燥方法、特に塗布液に有機溶剤を含む場合の通風乾燥方法では、乾燥の初期において塗布面の乾燥の不均一を招くため、風を吹きつけないで乾燥させる方法が、GB1401041 、US5168639 、US5694701 等に開示されている。
【００１２】
すなわち、GB1401041 には、風を吹かないで、塗布液中の溶媒を蒸発させ回収し乾燥させる方法が開示されている。この方法は、ケーシング上部に支持体の入り口、出口を設け、ケーシング内では非塗布面を加熱して塗布面からの溶媒の蒸発を促進し、塗布面側に設置した凝縮板に結露させる方法で溶媒を凝縮させて溶媒を回収し塗布膜を乾燥する方法である。
【００１３】
また、US5168639 には、水平に走行する支持体の上部でドラムを使って溶媒を回収する方法が開示されている。さらに、US5694701 では、US5168639 のレイアウトの改良方法についての提案がなされている。
【００１４】
【発明が解決しようとする課題】
しかし、GB1401041 では、支持体の入り口、出口がケーシング上部に限定されているために、装置のレイアウトにおいて制約が大きく、既存の塗布工程に組み込むのが難しい。また、Fig.5 に示される実施例では、塗布後回収ドライヤに入るまでに一定以上の距離が必要なことや回収ドライヤに入る前にベースを反転する必要があるため、塗布直後のムラを効率良く抑えることが困難である。
【００１５】
US5168639 では、塗布面から凝縮・溶剤回収ドラムまでの距離が塗布方向で変化することから、乾燥速度をケーシング内の全領域に亘って均一にコントロールすることが難しく、またケーシング入口、出口付近では塗布面と凝縮・冷却ドラムとの距離が不必要に離れてしまうため、自然対流の発生によって別の塗布ムラを生じてしまう。
【００１６】
US5168639 のレイアウトの改良方法では、塗布装置から凝縮・溶剤回収装置までの距離を接近させる構成を採ることが困難であり、塗布ムラ対策には不十分であった。
【００１７】
また、上記従来の溶剤の凝縮・回収方法においては、凝縮・回収装置における凝縮器、加熱装置等の設置位置、設定温度等を一定とし、装置内で均一に蒸発・回収させようとする。そのため、装置内での全域にわたって同一の乾燥速度に設定するには便利であるが、乾燥の初期、中期、後期の各段階で最適な条件を選んで乾燥させることが出来ない。すなわち、塗布ムラ抑制のための最適条件のコントロール、細かな乾燥膜質とする制御、等が困難であり、また、工程全体に亘り乾燥を効率化することが困難であった。
【００１８】
たとえば、乾燥速度を大きくするには、装置の凝縮面と塗布膜との距離を小さくする必要があるが、設定した距離精度の影響を受けやすい。また、距離精度を向上させた場合、一般的に装置の製造コストが飛躍的に高くなり、望ましくない。
【００１９】
また、乾燥初期のみ早く均一に乾燥させたい場合に、従来の方法では、凝縮・回収ゾーン全長にわたって、装置の凝縮面と塗布膜との距離を小さくするようにしていたため、装置全体での寸法精度を上げる必要があり、相当なコストの上昇となっていた。
【００２０】
一方、乾燥初期の乾燥速度を低く抑える場合には、凝縮・回収ゾーン全体の乾燥効率を下げる必要がある。この場合、凝縮・回収ゾーン全長を長くしなければならないという問題があった。
【００２１】
本発明は、このような事情に鑑みてなされたものであり、連続走行する帯状可撓性支持体に各種液状組成物を塗布して形成した長尺で広幅な塗布膜面において、塗布直後に発生する乾燥ムラを抑制し、かつ効率良く乾燥させる塗布膜の乾燥方法および装置を提供することを目的とする。
【００２２】
【課題を解決するための手段】
本発明は、前記目的を達成するために、走行する帯状可撓性支持体に塗布液を塗布手段により塗布し、塗布直後の走行位置に塗布液中の溶媒を凝縮、回収させるドライヤを配設する塗布膜の乾燥方法において、前記ドライヤには前記帯状可撓性支持体と所定距離をおいて略平行に板状部材である凝縮板を配設するとともに、該凝縮板と帯状可撓性支持体との距離を帯状可撓性支持体の走行方向で変化させることを特徴とする。
【００２３】
本発明によれば、連続走行する帯状可撓性支持体に各種液状組成物を塗布して形成した長尺で広幅な塗布膜面を乾燥させる方法において、塗布手段の直後に塗布液の溶媒を凝縮・回収するドライヤを配設し、かつ、そのドライヤには帯状可撓性支持体と所定距離をおいて略平行に板状部材である凝縮板を配設するとともに、凝縮板と帯状可撓性支持体との距離を帯状可撓性支持体の走行方向で変化させることにより、塗布直後に発生しやすい乾燥ムラを抑制し、かつ効率良く乾燥させることができる。
【００２４】
特に、塗布液中に有機溶剤が含まれている場合、または、塗布液の溶媒が全て有機溶剤で構成されている場合に効果が大きい。
【００２５】
また、本発明は、前記塗布液には有機溶剤を３質量％以上含有することを特徴とする。この場合にも本発明を適用することにより、塗布直後に発生する乾燥ムラを抑制し、かつ効率良く乾燥させることができる。
【００２６】
なお、有機溶剤とは、物質を溶解する性質をもつ有機化合物を意味し、トルエン、キシレン、スチレン等の芳香族炭化水素類、クロルベンゼン、オルトージクロルベンゼン等の塩化芳香族炭化水素類、モノクロルメタン等のメタン誘導体、モノクロルエタン等のエタン誘導体等を含む塩化脂肪族炭化水素類、メタノール、イソプロピルアルコール、イソブチルアルコール等のアルコール類、酢酸メチル、酢酸エチル等のエステル類、エチルエーテル、1,4-ジオキサン等のエーテル類、アセトン、メチルエチルケトン等のケトン類、エチレングリコールモノメチルエーテル等のグリコールエーテル類、シクロヘキサン等の脂環式炭化水素類、ノルマルヘキサン等の脂肪族炭化水素類、脂肪族または芳香族炭化水素の混合物等が該当する。
【００２７】
【発明の実施の形態】
以下、添付図面に従って本発明に係る塗布膜の乾燥方法および装置の好ましい実施の形態について詳説する。
【００２８】
図１〜８は、本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０の各例をそれぞれ示す概念図である。
【００２９】
図示されるように、塗布・乾燥ライン１０は、主として、ロール状に巻回された帯状可撓性支持体１２を送り出す送り出し装置（図示略）、帯状可撓性支持体１２に塗布液を塗布する塗布手段１６、帯状可撓性支持体１２に塗布形成された塗布膜の塗布液中の溶媒を凝縮、回収させるドライヤ１８からなる乾燥装置、および塗布・乾燥により製造された製品を巻き取る巻き取り装置（図示略）と、帯状可撓性支持体１２が走行する搬送経路を形成する多数のガイドローラ２２、２２…とで形成される。
【００３０】
帯状可撓性支持体１２としては、ポリエチレン、ＰＥＴ（ポリエチレンテレフタレート）、ＴＡＣ（トリアセテート）等の樹脂フィルム、紙、金属箔等を使用できる。
【００３１】
塗布手段１６は、各種方式のものが使用できる。たとえば、スロット・ダイコータ（図１、図５、図７参照）、ワイヤーバーコータ（図２、図４、図８参照）、ロールコータ、グラビアコータ（図６参照）、スライドホッパ塗布方式（図３参照）、カーテン塗布方式、等が使用できる。
【００３２】
なお、塗布手段１６は、図１、図３、図５、図７に示されるように塗布面が水平方向に対して上側になるような構成であってもよいし、図２、図４、図６、図８に示されるように水平方向に対して下側になるような構成であってもよい。また、水平方向に対して傾斜するような構成であってもよい。
【００３３】
図９に示されているように、塗布手段１６の前段に除塵設備７０を設置したり、帯状可撓性支持体１２の表面に前処理等を施してもよい。ゴミ等の殆どない高い品質が求められる光学性フイルム等では、これらを同時に採用することで、高品質な塗布、乾燥膜を得ることができる。
【００３４】
ドライヤ１８は、帯状可撓性支持体１２と所定距離をおいて略平行に設けられる板状部材である凝縮板２０と、凝縮板２０の前後辺から下方に垂設される側面板等とで構成される。これにより、塗布膜の塗布液中の溶媒が揮発した際に、揮発した溶媒が凝縮板２０に凝縮し回収される構成となっている。
【００３５】
凝縮板２０の溶媒を凝縮させる面に用いる材質は、金属、プラスチック、木材等、特に限定はされないが、塗布液中に有機溶剤が含まれる場合には、その有機溶剤に対して耐性のある材料を使用するか、または表面にコーティングを施すことが望ましい。
【００３６】
ドライヤ１８において、凝縮板３０に凝縮した溶媒を回収させる手段は、たとえば、凝縮板３０の凝縮面に溝を設け、毛管力を利用して溶媒を回収させる。溝の方向は、帯状可撓性支持体１２の走行方向であってもよく、これに直交する方向であってもよい。凝縮板３０が傾斜している場合には、溶媒を回収させやすい方向に溝を設ければよい。
【００３７】
図１０に示される例において、凝縮板３０右端の下方には凝縮した溶媒を回収するための樋３０ａが設けられており、樋３０ａを経て溶媒が回収される。
【００３８】
ドライヤ１８に板状部材である凝縮板２０を採用する構成以外に、同様な機能を奏する構成、たとえば、多孔板、網、簀の子、ロール等を使用する構成も採用できる。また、US5694701 に示されるような回収装置と併用してもよい。
【００３９】
ドライヤ１８には、帯状可撓性支持体１２と所定距離をおいて略平行に板状部材である凝縮板２０が配設されており、凝縮板２０と帯状可撓性支持体１２との距離を帯状可撓性支持体の走行方向で変化できる構成となっている
凝縮板２０と帯状可撓性支持体１２との距離を帯状可撓性支持体の走行方向で変化させる構成としては、図１、図２に示されるように、複数の凝縮板２０、２０、２０を配設するとともに、凝縮板２０と帯状可撓性支持体１２との距離を階段状に変化させる構成であっても、凝縮板２０を帯状可撓性支持体１２の走行方向に向かって所定角度傾斜させ、凝縮板２０と帯状可撓性支持体１２との距離を帯状可撓性支持体１２の走行方向でテーパ状に変化させる構成（図示略）であってもよい。この場合、凝縮板２０を帯状可撓性支持体１２の走行方向に向かって傾斜させる角度は、水平に対し３０度以下が好ましく、２０度以下がより好ましい。
【００４０】
また、上記と同様の効果を奏すべく、ドライヤ１８には帯状可撓性支持１２の走行方向に沿って複数の凝縮板２０、２０、２０を配設するとともに、凝縮板２０、２０同士を離して配設する構成、または、図７に示されるように、凝縮２０、２０同士の間に仕切り板２８、２８、２８を配設する構成、さらには、複数の箱状のドライヤ１８、１８、１８にそれぞれ凝縮板２０、２０、２０を設け、箱状のドライヤ１８、１８同士を密着させる構成、または、ドライヤ１８、１８同士を離して配する構成のいずれも採り得る。
【００４１】
ドライヤ１８および凝縮板２０は、必ずしも図１、図２等に示されるような直線状である必要はなく、たとえば、図５、図７に示されるような円弧状のドライヤ１８および凝縮板２０であってもよい。また、大きなドラムを設け、それ凝縮板を配設してもよい。
【００４２】
なお、図５、図７に示される例では、円弧状のドライヤ１８および凝縮板２０を塗布手段１６に近づけて溶媒の回収効率の向上を図っている。
【００４３】
ドライヤ１８は、塗布液を塗布した直後の自然対流の発生による塗布膜の乾燥ムラを防止するため、塗布手段１６のできるだけ近くに配設することが好ましい。具体的には、ドライヤ１８の入口が塗布手段１６から５ｍ以内の位置になるように配設することが好ましく、ドライヤ１８の入口が塗布手段１６から２ｍ以内の位置になるように配設することがより好ましく、ドライヤ１８の入口が塗布手段１６から０．７ｍ以内の位置になるように配設することが最も好ましい。
【００４４】
同様の理由で、帯状可撓性支持体１２の走行速度は、帯状可撓性支持体１２が塗布手段１６による塗布後３０秒以内にドライヤ１８に到達する速度であることが好ましく、帯状可撓性支持体１２が塗布手段１６による塗布後２０秒以内にドライヤ１８に到達する速度であることがより好ましい。
【００４５】
塗布液の塗布量および塗布膜厚さは、大きい程塗布膜内部での流動が起きやすいことよりムラが発生しやすいが、本発明によれば、塗布量および塗布膜厚さが大きい場合でも十分な効果が得られる。塗布膜の厚さが０．００１〜０．０８ｍｍであれば、ムラなくかつ効率よく乾燥することができる。
【００４６】
帯状可撓性支持体１２の走行速度が大きすぎると、同伴風によって塗布膜近傍の境界層が乱され、塗布膜に悪影響を及ぼす。したがって、帯状可撓性支持体１２の走行速度は１〜１００ｍ／分に設定することが好ましく、５〜８０ｍ／分に設定することがより好まい。
【００４７】
塗布液中の溶媒の蒸発、凝縮を促進させるため、帯状可撓性支持体１２および／または塗布膜を加熱するか、凝縮板２０を冷却するか、またはその両手段を採用することが好ましい。たとえば、ドライヤに冷却手段（図示略）を配し、また、帯状可撓性支持体１２を挟んでドライヤ１８の反対側に加熱手段２４、２４を配する（図４、図６、図８参照）。
【００４８】
いずれの場合も、塗布膜の乾燥速度を制御するために、温度管理されていることが望ましい。凝縮板２０は、温度コントロールできるようにし、冷却したい場合には、冷却するための設備を設置する必要がある。冷却には、冷媒等を使った水冷式の熱交換器方式のもの、風を使った空冷式、電気を用いた方式、たとえばペルチェ素子を使用した方式、等を用いることができる。
【００４９】
帯状可撓性支持体１２もしくは塗布膜、またはその両方を加熱したい場合には、反塗布膜側にヒータを配設して加熱することができる。また、昇温可能な搬送ロール（加熱ロール）を配設して加熱することもできる。その他、赤外線ヒータ、マイクロ波加熱手段等を用いて加熱してもよい。
【００５０】
帯状可撓性支持体１２、塗布膜、凝縮板２０の温度を決定する際、注意しなければならないのは、蒸発させた溶媒が凝縮板２０以外の場所、たとえば、搬送ロールの表面等に結露しないようにしなければならないことである。このため、たとえば、凝縮板２０以外の部分の温度を凝縮板２０の温度よりも高くしておくことによりこの種の結露を回避することができる。
【００５１】
塗布膜の表面とドライヤ１８の凝縮板２０表面との距離（間隔）は、所望の塗布膜の乾燥速度を考慮した上で、適当な距離に調整する必要がある。距離を短くすると乾燥速度が上がる一方、設定した距離精度の影響を受けやすい。一方、距離を大きくすると乾燥速度が大幅に低下するのみならず、熱による自然対流が起きて乾燥ムラを引き起こす。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は、０．１〜２００ｍｍが好ましく、０．５〜１００ｍｍがより好ましい。
【００５２】
また、加熱手段２４、２４の設定温度を帯状可撓性支持体１２の走行方向で変化させる構成も採り得る。たとえば、図４、図６等において、帯状可撓性支持体１２の走行方向で上流側の加熱手段２４の設定温度を下流側の加熱手段２４の設定温度より低くする。このように設定することにより、乾燥ムラをさらに抑制することもできる。
【００５３】
同様に、ドライヤ１８の冷却手段の設定温度を帯状可撓性支持体の走行方向で変化させる構成も採り得る。図４、図６等において、帯状可撓性支持体１２の走行方向で上流側のドライヤ１８の冷却手段の設定温度を下流側の冷却手段の設定温度と異ならせる。なお、図４、図６の構成では、複数の凝縮板２０、２０、２０を配設するとともに、凝縮板２０と帯状可撓性支持体１２との距離を階段状に変化させる構成と組み合わされている。
【００５４】
その他、加熱手段２４、２４の設定温度を階段状に変化させる構成、ドライヤ１８の冷却手段の設定温度を階段状に変化させる構成、または、これらを組み合わせた構成等、各種の態様が採り得る。
【００５５】
なお、本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０に使用されている送り出し装置、ガイドローラ２２、巻き取り装置等には慣用の部材を使用しており、それらの説明は省略する。
【００５６】
以上に詳述した本発明の塗布膜の乾燥装置によれば、塗布直後の塗布膜に発生するムラを抑制しかつ効率よく均一に塗布膜を乾燥できる。また、塗布、乾燥工程のレイアウトを大きく変更することなく、さらに、塗布液の物性や溶媒の種類等に制約されないので、塗布液処方手段の柔軟な設計が可能である。
【００５７】
すなわち、たとえば既存の通風乾燥装置を含む塗布・乾燥装置の塗布部と通風乾燥装置との間に溶媒を凝縮・回収するドライヤを増設するだけで、本発明の装置と同様の形態とでき、その結果、低コストで装置改造ができる。
【００５８】
また、本発明の塗布膜の乾燥装置によれば、省エネルギー化、コストダウンにも効果がある。すなわち、塗布・乾燥ラインで発生する蒸発気体のうち水以外の溶媒はそのまま大気へ放出できないので、蒸発気体を液化して回収する必要があり、そのための溶剤ガス回収設備が必要である。ところが、塗布・乾燥ライン１０では、塗布液の一部を凝縮・回収するドライヤにより溶媒を液体の状態で直接回収できるため、溶剤ガス回収設備の負荷を減らすことができる。
【００５９】
本発明の塗布膜の乾燥装置を通風乾燥装置と併用した場合には、風を吹くための送風設備を大幅に削減できる。そのため、空調設備費等のコストも大幅に削減できる、また、設備を非常にコンパクトにできる。
【００６０】
また、本発明の塗布膜の乾燥装置を用いると、乾燥初期において非常に均一な乾燥が可能なため、次のような予期しなかった効果が得られることがわかった。すなわち、従来の通風乾燥装置では、塗布膜を乱す影響を完全には抑えられないため、塗布膜内に流動を生じていたが、本発明の装置を用いると、それらの流動を防止でき、また、乾燥中に形成される塗布膜中の高分子、粒子のネットワークの構造を非常に細かく、しかも均一に形成できることがわかった。
【００６１】
これにより、単に塗布膜を均一に乾燥させるだけのみならず、塗布膜の構造が細かくなることにより、たとえば、光学フイルムの場合、新たな付加機能を追加できることにもつながる。
【００６２】
また、本発明の塗布膜の乾燥装置は、たとえば、ナノ粒子等が含まれる機能性膜の乾燥等にも非常に適しているといえる。
【００６３】
本発明の塗布膜の乾燥装置は、塗布液に高分子や粒子等の固形分が溶解または分散されたものに適用した場合でも、同様の効果が得られる。むしろ、粒子等が含まれる系では、乾燥ムラの発生が塗布膜中の粒子の分散分布にも大きく影響する。したがって、この系に本システムを使用することは好ましい。
【００６４】
【実施例】
［実施例１］
図９に示される光学補償シートの製造ラインにおける塗布層の乾燥工程に、塗布液中の溶媒を凝縮、回収させるドライヤ１８を配設して、光学補償シートを製造する上での好適なドライヤの構造および溶媒の凝縮、回収条件を検討した。
【００６５】
図９に示されるように、光学補償シートの製造ラインは、たとえば下記の工程により行われる。
１）透明フィルム１２の送出工程５０；
２）透明フィルムの表面に配向膜形成用樹脂を含む塗布液を塗布、乾燥する配向膜形成用樹脂層の形成工程５２；
３）表面に配向膜形成用樹層が形成された透明フィルム上に、樹脂層の表面にラビング処理を施し透明フィルム上に配向膜を形成するラビング工程５４；
４）液晶性ディスコティック化合物を含む塗布液を、配向膜上に塗布する液晶性ディスコティック化合物の塗布工程１６；
５）該塗布膜を乾燥して該塗布膜中の溶媒を蒸発させる乾燥工程１８；
６）該塗布膜をディスコティックネマティック相形成温度に加熱して、ディスコティックネマティック相の液晶層を形成する液晶層形成工程５８；
７）該液晶層を固化する（すなわち、液晶層形成後急冷して固化させるか、または、架橋性官能基を有する液晶性ディスコティック化合物を使用した場合、液晶層を光照射（または加熱）により架橋させる）工程６０；
８）該配向膜および液晶層が形成された透明フィルムを巻き取る巻取り工程２４。
【００６６】
なお、図９において、６２は乾燥ゾーンを、６４は検査装置を、６６は保護フィルムを、６８はラミネート機を、７０は徐塵設備をそれぞれ示す。
【００６７】
光学補償シートの製造方法は、図３に示されるように長尺状透明フィルムを送り出す工程から、得られた光学補償シートを巻き取る工程まで一貫して連続的に行なった。トリアセチルセルロース（フジタック、富士写真フィルム（株）製、厚さ：１００μｍ、幅：５００ｍｍ）の長尺状のフィルムの一方の側に、長鎖アルキル変成ポバール（ＭＰ−２０３、クラレ（株）製）５重量％溶液を塗布し、９０℃で４分間乾燥させた後、ラビング処理を行って膜厚２．０μｍの配向膜形成用樹脂層を形成した。フィルムの搬送速度は、２０ｍ／分であった。
【００６８】
上記トリアセチルセルロースフィルムは、フィルム面内の直交する二方向の屈折率をｎｘ、ｎｙ、厚さ方向の屈折率をｎｚ、そしてフィルムの厚さをｄとしたとき、（ｎｘ−ｎｙ）×ｄ＝１６ｎｍ、｛（ｎｘ−ｎｙ）／２−ｎｚ｝×ｄ＝７５ｎｍであった。また、上記配向膜形成用樹脂層の形成は、塗布・乾燥装置を用いて行なった。
【００６９】
続いて、得られた樹脂層を有するフィルムを、連続して２０ｍ／分で搬送しながら、樹脂層表面にラビング処理を施した。ラビング処理は、ラビングローラの回転数を３００ｒｐｍにて行い、次いで得られた配向膜の除塵を行った。
【００７０】
次いで、得られた配向膜を有するフィルムを、連続して２０ｍ／分の速度で搬送しながら、配向膜上に、ディスコティック化合物ＴＥ−８の（３）とＴＥ−８の（５）の重量比で４：１の混合物に、光重合開始剤（イルガキュア９０７、日本チバガイギー（株）製）を上記混合物に対して１重量％添加した混合物の１０重量％メチルエチルケトン溶液（塗布液）を、ワイヤーバー塗布機にて、塗布速度を２０ｍ／分、塗布量を５ｃｃ／m²で塗布し、次いで乾燥および加熱ゾーンを通過させた。乾燥ゾーンには風を送り、加熱ゾーンは１３０℃に調整した。塗布後３秒後に乾燥ゾーンに入り、３秒後に加熱ゾーンに入った。加熱ゾーンは約３分で通過した。
【００７１】
続いて、この配向膜および液晶層が塗布されフィルムを、連続して２０ｍ／分で搬送しながら、液晶層の表面に紫外線ランプにより紫外線を照射した。すなわち、上記加熱ゾーンを通過したフィルムは、紫外線照射装置（紫外線ランプ：出力１６０Ｗ／ｃｍ、発光長１．６ｍ）により、照度６００ｍＷの紫外線を４秒間照射し、液晶層を架橋させた。
【００７２】
上記の工程により、６種類の条件で試験を行った。以下に、その条件および結果を記す。
【００７３】
（試験１）
ヒータ温度を８５℃、凝縮板温度を２５℃とした。ドライヤ１８は、入口が塗布手段１６から５００ｍｍの位置となるように配した。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は３ｍｍとした。
【００７４】
その結果、塗布膜を完全に乾燥させるのに６ｍの走行距離を要した。塗布膜品質に問題は生じなかった。
【００７５】
（試験２）
ヒータ温度を８５℃、凝縮板温度を２５℃とした。ドライヤ１８は、入口が塗布手段１６から５００ｍｍの位置となるように配した。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は０．５ｍｍとした。
【００７６】
その結果、塗布膜を乾燥させるのに１ｍの走行距離を要した。塗布膜には幅方向に乾燥ムラを生じ、また、配向不良も発生した。
【００７７】
（試験３）
ヒータ温度を８５℃、凝縮板温度を２５℃とした。ドライヤ１８は、入口が塗布手段１６から５００ｍｍの位置となるように配した。凝縮板２０は３個のゾーンに分割した。また、３個の凝縮板２０は、いずれも走行方向の下流側が塗布膜から離れるような５度の傾斜角度をもって配した。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は、３個の凝縮板２０の走行方向の下流側に向かって、それぞれ、３ｍｍ、１．５ｍｍ、０．５ｍｍとした。
【００７８】
その結果、塗布膜を完全に乾燥させるのに１．８ｍの走行距離を要した。塗布膜品質に問題は生じなかった。すなわち、この条件では、工程長さの短縮と良好な塗布膜品質の両立が可能であった。
【００７９】
（試験４）
ヒータ温度を６０℃、凝縮板温度を２５℃とした。ドライヤ１８は、入口が塗布手段１６から５００ｍｍの位置となるように配した。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は１ｍｍとした。
【００８０】
その結果、塗布膜を完全に乾燥させるのに５ｍの走行距離を要した。塗布膜品質に問題は生じなかった。
【００８１】
（試験５）
ヒータ温度を６０℃、凝縮板温度を１５℃とした。ドライヤ１８は、入口が塗布手段１６から５００ｍｍの位置となるように配した。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は１ｍｍとした。
【００８２】
その結果、塗布膜を完全に乾燥させるのに２ｍの走行距離を要した。塗布膜には幅方向に乾燥ムラを生じ、また、配向不良も発生した。
【００８３】
（試験６）
ヒータ温度を６０℃とした。ドライヤ１８は、入口が塗布手段１６から５００ｍｍの位置となるように配した。凝縮板２０は３個のゾーンに分割した。また、３個の凝縮板２０の凝縮板温度は、走行方向の下流側に向かって、それぞれ２５℃、２０℃、１５℃とした。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は１ｍｍとした。
【００８４】
その結果、塗布膜を完全に乾燥させるのに０．８ｍの走行距離を要した。塗布膜品質に問題は生じなかった。すなわち、この条件では、工程長さの短縮と良好な塗布膜品質の両立が可能であった。
【００８５】
［実施例２］
感光用セルロースアセテートフィルムの製造ラインにおける下塗り塗布後の乾燥工程において、本発明における塗布液中の溶媒を凝縮、回収させるドライヤを配設した場合と、従来の通風乾燥タイプの乾燥器を配設した場合とを比較した。
【００８６】
図１０に示される、本発明におけるドライヤを使用した製造ラインにおいて、セルロースアセテートドープが流延ダイから流延ドラム面上に流延され、それによって形成されたフィルムが剥ぎ取りローラで剥ぎ取られ、前乾燥工程のロール間を走行する間に熱風により乾燥される。
【００８７】
次いで、写真感光材料用下塗りを行い、さらにドライヤ１８で乾燥させる。残留溶媒が約１０％以下となった時点で、幅規制装置（図示略）に導き幅方向に２〜６％延伸させ、さらに緊張状態のまま冷却した後に巻き取られる。
【００８８】
ドライヤ１８の凝縮板２０は２個のゾーンに分割した。また、２個の凝縮板２０は、いずれも走行方向の下流側が塗布膜から離れるような傾斜角度をもって配した。塗布膜の表面とドライヤ１８の凝縮板２０表面との距離は、走行方向の下流側に向かって、上流側の凝縮板２０の入口側で０．８ｍｍ、出口側で２ｍｍとし、下流側の凝縮板２０の入口側で０．８ｍｍ、出口側で２ｍｍとした。
【００８９】
また、上流側の凝縮板２０の長さを２ｍ、下流側の凝縮板２０の長さを４ｍとした。凝縮板２０の設定温度は、いずれも１５℃とした。
【００９０】
製造した製品の表面性状は良好であった。
【００９１】
図１１に示される、従来の通風乾燥タイプの乾燥器を使用した製造ラインにおいて、下塗り塗布乾燥工程の装置は、通常の通風乾燥タイプの乾燥器である。製造ラインのその他の部分は図１０に示される構成同様であり、説明を省略する。
【００９２】
製造した製品の表面性状は、下塗りでの乾燥ムラを生じ不良となった。
【００９３】
［実施例３］
熱現像感光材料の製造ラインの乾燥工程に、凝縮・回収するドライヤ（前段側）と通風乾燥手段（後段側）とを組み合わせた乾燥手段を配設した場合の実施例と、従来の通風乾燥タイプの乾燥手段のみを配設した場合の比較例とを対比した。
【００９４】
帯状可撓性支持体に塗布する熱現像感光材料用の塗布液は次のように調製した。
【００９５】
１）ハロゲン化銀粒子の調製
水７００ｍリットルにフタル化ゼラチン２２ｇおよび臭化カリウム３０ｍｇを溶解して温度３５℃にてＰＨを５に調整した後、硝酸銀１８．６ｇを含む水溶液１５９ｍリットルと臭化カリウムと沃化カリウムとを９２：８のモル比で含む水溶液をｐＡｇ７．７に保ちながらコントロールダブルジェット法で１０分間かけて添加した。ついで、硝酸銀５５．４ｇを含む水溶液４７６ｍリットルと六塩化イリジウム酸第二カリウムを１０．５μモル／リットルと、臭化カリウムを１モル／リットルで含む水溶液ｐＡｇ７．７に保ちながらコントロールダブルジェット法で３０分間かけて添加した。その後、ＰＨを下げて凝集沈降させ脱塩処理をし、フェノキシエタノール０．１１ｇを加え、ＰＨ５．９，ｐＡｇ８．２に調整し、沃臭化銀粒子（沃素含量コア８モル％、平均２モル％、平均サイズ０．０５μｍ、投影面積変動係数８％、（１００）面比率９０％の立方体粒子）を調製した。
【００９６】
こうして得たハロゲン化銀粒子を６０℃に昇温して銀１モル当たりチオ硫酸ナトリウム８５μモルと、2,3,4,5,6 ペンタフルオロフェニルジフェニルフォスフィンセレニドを１１μモル、１５μモルのテルル化合物、塩化金酸３．６μモル、チオシアン酸２８０μモルを添加し、１２０分間熟成した後、３０℃に急冷してハロゲン化銀乳剤を得た。
【００９７】
２）有機酸銀乳剤の調製
ステアリン酸１．３ｇ、アラキジン酸０．５ｇ、ベヘン酸８．５ｇ、蒸留水３００ｍリットルを、９０℃で４０分間混合し、激しく攪拌しながら１Ｎの水酸化ナトリウム水溶液３１．１ｍリットルを１５分かけて添加した後、３０℃に昇温した。次に、１Ｎのリン酸水溶液７ｍリットルを添加し、より激しく攪拌しながらＮ−ブロモスクシンイミド０．０１２ｇを添加した後、あらかじめ調製したハロゲン化銀粒子をハロゲン化銀量が２．５ｍモルになるように添加した。さらに、１Ｎの硝酸銀水溶液２５ｍリットルを２５分かけて添加し、そのまま９０分間攪拌し続けた。その後、吸引ろ過で固形分をろ別し、固形分をろ過水の伝導度が３０μＳ・ｃｍになるまで水洗いした。こうして得られた固形分にポリ酢酸ビニルの１．２重量％の酢酸ブチル溶液３７ｇを加えて攪拌し、攪拌を止めて放置し、油層と水層に分離させ、含まれる塩とともに水層を除去し、油層を得た。次に、この油層にポリビニルブチラールの２．５重量％２−ブタノン溶液２０ｇを添加し攪拌した。さらに、過臭化ピリジニウム０．１ｍモルと、臭化カルシウム二水和物０．１８ｍモルを０．７ｇメタノールとともに添加した後、２−ブタノン４０ｇとポリビニルチラールの７．８ｇを添加し、ホモジナイザで分散し、有機酸銀塩乳剤（平均短径０．０４μｍ、平均長径１μｍ、変動係数３０％の針状粒子）を得た。
【００９８】
３）乳剤層塗布液の調製
上記で得た有機酸銀塩に銀１モル当たり以下の量になるように各薬品を添加した。２５℃でフェニルチオスルホン酸ナトリウム１０ｍｇ、６８ｍｇの色素１、３０ｍｇの色素２、２−メルカプト−５−メチルベンゾイミダゾール２ｇ、４−クロロベンゾフェノン−２−カルボン酸２１．５ｇと、２−ブタノン５８０ｇ、ジメチルホルムアミド２２０ｇを攪拌しながら添加し、３時間放置した。ついで、５−トリブロモメチルスルフォニル−２−メチルチアジアゾール８ｇ、２−トリブロモメチルスルフォニルベンゾチアゾール６ｇ、４，６−ジトリクロロメチル−２−フェニルトリアジン５ｇ、ジスルフィド化合物２ｇ、１，１−ビス（２−ヒドロキシ−３，５−ジメチルフェニル）−３，５，５トリメチルヘキサン１６０ｇ、テトラクロロフタル酸５ｇ、１．１ｇのフッ素系界面活性剤、２−ブタノン５９０ｇ、メチルイソブチルケトン１０ｇを攪拌しながら添加した。
【００９９】
上記の如く調製した乳剤層塗布液を青色染料で色味付けした１７５μｍのポリエチレンテレフタレート支持体（帯状可撓性支持体）に、銀が２．３ｇ／ｃｍ²になるように塗布した。そして、塗布後、実施例の場合には凝縮・回収するドライヤ（前段側）と通風乾燥手段（後段側）とで乾燥させた後、紫外線照射して熱現像感光材料を得た。一方、比較例の場合には塗布膜を通風乾燥タイプの乾燥器のみで乾燥した後、紫外線照射して熱現像感光材料を得た。
【０１００】
実施例の方法で製造した製品の表面性状は良好であった。一方、比較例の方法で製造した製品の表面性状は、風ムラの影響を受け不良となった。
【０１０１】
［実施例４］
ハードコートフィルムの製造ラインの乾燥工程に、凝縮・回収するドライヤ（前段側）と通風乾燥手段（後段側）とを組み合わせた乾燥手段を配設した場合の実施例と、従来の通風乾燥タイプの乾燥手段のみを配設した場合の比較例とを対比した。
【０１０２】
帯状可撓性支持体に塗布するハードコート塗布液は次のように調製した。
１）無機粒子分散液（Ｍ−１）の調製
セラミックコートがなされた容器に、以下の各試薬を以下の配合量で配合して混合液を調製した。
【０１０３】
・シクロヘキサン…３３７ｇ
・リン酸基含有メタアクリレート（ＰＭ−２：日本化薬製）…３１ｇ
・アルミナ（ＡＫＰ−Ｇ０１５：住友化学工業製、粒径１５ｎｍ）…９２ｇ
得られた混合液をサンドミル（１／４Ｇのサンドミル）にて１６００ｒｐｍ、１０時間微細分散した。メディアとしては１ｍｍφのジルコニアビーズを１４００ｇ用いた。分散後、ジルコニアビーズを分離し、表面修飾した無機粒子分散液（Ｍ−１）を得た。
【０１０４】
２）活性エネルギー線硬化層用塗布液の調製
表面処理したアルミナ微粒子の４３重量％シクロヘキサン分散液（Ｍ−１）１１６ｇに、メタノール９７ｇ、イソプロパノール１６３ｇ、およびメチルイソブチルケトン１６３ｇを加えた。この混合液にジペンタエリスリトールペンタアクリレートとジペンタエリスリトールヘキサアクリレートとの混合物（ＤＰＨＡ、日本化薬製）２００ｇを加えて溶解した。さらに、光重合開始剤（イルガキュア１８４、チバガイギー社製）７．５ｇを加えて溶解した。この混合物を３０分間攪拌した後、孔径１μｍのポリプロピレン製フィルタでろ過して活性エネルギー線硬化層用塗布液を調製した。
【０１０５】
３）帯状可撓性支持体（基材フィルム）をグロー放電処理した後、アルミナを含有した活性エネルギー線硬化層用塗布液が乾燥膜厚が８μｍになるようにワイヤーバー塗布手段により塗布した。そして、塗布後、実施例の場合には凝縮・回収するドライヤ（前段側）と通風乾燥手段（後段側）とで乾燥させた後、紫外線照射して硬化層を得た。一方、比較例の場合には塗布膜を通風乾燥タイプの乾燥器のみで乾燥した後、紫外線照射して硬化層を得た。
【０１０６】
次に、厚膜ハードコートフィルムの製造ラインの乾燥工程に、凝縮・回収するドライヤ（前段側）と通風乾燥手段（後段側）とを組み合わせた乾燥手段を配設した場合の実施例と、従来の通風乾燥タイプの乾燥手段のみを配設した場合の比較例とを対比した。
【０１０７】
帯状可撓性支持体に塗布する厚膜ハードコート塗布液は次のように調製した。
【０１０８】
１）開環重合性基含有化合物（Ｋ−１）の調製
メチルエチルケトン（ＭＥＫ）２７５ｍリットルを窒素気流下で、６０℃で１時間攪拌した後、重合開始剤（Ｖ−６５：和光純薬製）０．５ｇをＭＥＫ８．３ｍリットルに溶解したものを全量添加した重合開始剤添加溶液を調製した。その後、グリシジルメタクリレート５０ｇを２時間かけて滴下し、滴下終了後、調製しておいた重合開始剤添加溶液を添加し、２時間反応させた。その後、反応温度を８０℃として２時間反応させ、反応終了後、室温まで冷却させた。得られた反応溶液をヘキサン１０リットルに、１時間かけて滴下し、沈殿物を３５℃、８時間減圧乾燥して開環重合性基含有化合物（Ｋ−１）を得た。
【０１０９】
２）硬化性組成物の調製
トリメチロールプロパントリアクリレート（エチレン性不飽和基含有化合物）７５部と、前記調製した開環重合性基含有化合物（Ｋ−１）２５部と、ラジカル重合開始剤（イルガキュア１８４、チバガイギー社製）と、カチオン重合開始剤（ＵＶＩ−６９９０：ユニオンカーバイド日本社製）を、メチルイソブチルケトン／メチルエチルケトン（１／５）混合溶液４０部に溶解後、３０分攪拌し、硬化性組成物を得た。なお、重合開始剤は、エチレン性不飽和基含有化合物と開環重合性基含有化合物との総質量に対し、ラジカル重合開始剤と、カチオン重合開始剤とを２．９重量％ずつ添加した。
【０１１０】
３）透明な帯状可撓性支持体（透明基材フィルム）として、厚さ１８８μｍのポリエチレンテレフタレートフィルムをグロー放電処理した後、上記調製した硬化性組成物をエクストルージョン型の塗布方法により塗布した。そして、塗布後、実施例の場合には凝縮・回収するドライヤ（前段側）と通風乾燥手段（後段側）とで乾燥させた後、紫外線照射し、さらに１２０℃で１０分加熱することにより厚膜ハードコートフィルムを得た。一方、比較例の場合には塗布膜を通風乾燥タイプの乾燥器のみで乾燥した後、紫外線照射し、さらに１２０℃で１０分加熱することにより厚膜ハードコートフィルムを得た。なお、乾燥は１２０℃で２分、紫外線照射は７５０ｍｊ／ｃｍ²の条件で行った。
【０１１１】
実施例の方法で製造した製品の表面性状は良好であった。一方、比較例の方法で製造した製品の表面性状は、風ムラの影響と思われる厚さムラを生じ不良となった。
【０１１２】
【発明の効果】
本発明の塗布膜の乾燥方法および装置によれば、連続走行する帯状可撓性支持体に各種液状組成物を塗布して形成した長尺で広幅な塗布膜面において、塗布直後に発生する乾燥ムラを抑制しかつ効率よく均一に塗布膜を乾燥できる。
【０１１３】
また、塗布、乾燥工程のレイアウトを大きく変更することなく、さらに、塗布液の物性や溶媒の種類等に制約されないので、塗布液処方手段の柔軟な設計が可能である。また、省エネルギー化、コストダウンにも効果がある。
【０１１４】
さらに、塗布膜内の流動を防止でき、また、乾燥中に形成される塗布膜中の高分子、粒子のネットワークの構造を非常に細かく、しかも均一に形成できる。
【図面の簡単な説明】
【図１】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０の一例を示す概念図
【図２】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０の他の例を示す概念図
【図３】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０のさらに他の例を示す概念図
【図４】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０のさらに他の例を示す概念図
【図５】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０のさらに他の例を示す概念図
【図６】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０のさらに他の例を示す概念図
【図７】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０のさらに他の例を示す概念図
【図８】本発明の塗布膜の乾燥方法および装置が適用される乾燥装置を組み込んだ塗布・乾燥ライン１０のさらに他の例を示す概念図
【図９】本発明の塗布膜の乾燥装置を光学補償シートの製造ラインに適用した例を示す概念図
【図１０】本発明の塗布膜の乾燥装置を感光用セルロースアセテートフィルムの製造ラインに適用した例を示す概念図
【図１１】従来例である通風乾燥タイプの乾燥器を感光用セルロースアセテートフィルムの製造ラインに適用した例を示す概念図
【符号の説明】
１０…塗布・乾燥ライン、１２…帯状可撓性支持体、１６…塗布手段、１８…ドライヤ、２０…凝縮板、２２…ガイドローラ、２４…加熱手段、２８…仕切り板[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a coating film drying method and apparatus, and in particular, a drying method for drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support and Relates to the device.
[0002]
This technology includes optical functional film sheets such as optical compensation sheets, solvent undercoats of photosensitive film materials, photothermographic materials, functional films containing finely structured particles such as nanoparticles, photographic films, and photographic prints. Used in the manufacture of paper, magnetic recording tape, adhesive tape, pressure-sensitive recording paper, offset plate materials, batteries, etc.
[0003]
[Prior art]
For a drying method and apparatus for drying a long and wide coating film surface formed by coating various liquid compositions on a continuous belt-like flexible support, see `` Coating and Drying Defects '' by EBGutoff, EDCohen. Wiley-Intersciece, John Wiley & Sons, Inc.) Supports the non-application surface side with a roll, blows air from the air nozzle to the application surface side and dries the air, and both the application surface and non-application surface air nozzle A non-contact type air floating drying method is described in which the air is blown to float the support, that is, the support is dried without contacting the roll or the like. As for this non-contact type drying method, there is a drying method using a string winding type drying device as disclosed in Japanese Patent Publication No. 48-42903 as a method of efficiently using space and drying efficiently. .
[0004]
Usually, in the method of drying by blowing these winds (hereinafter referred to as ventilation drying method), the air contained in the coating surface is evaporated and dried by blowing the conditioned air on the coating surface. Although this ventilation drying method is excellent in drying efficiency, since the wind is applied directly or through a porous plate, a rectifying plate, etc., the coating surface is disturbed by this wind, and the thickness of the coating layer becomes uneven. Unevenness occurs or the evaporation rate of the solvent on the coating surface becomes uneven due to convection. There was a problem that a uniform coating layer could not be obtained.
[0005]
In particular, when the coating solution contains an organic solvent, the occurrence of such unevenness is remarkable. The reason for this is that the organic film is sufficiently contained in the coating film at the initial stage of drying, and if the evaporation distribution of the organic solvent occurs at this stage, the temperature distribution and surface tension distribution on the coating film surface will result. This is because a flow such as so-called Marangoni convection occurs in the coating film surface. The occurrence of such unevenness becomes a serious coating defect.
[0006]
When the liquid crystal is included in the coating film, not only the above-mentioned drying unevenness but also a problem such as a deviation in the orientation of the liquid crystal on the coating film surface due to the blowing wind occurs.
[0007]
As a method for solving these problems, Japanese Patent Laid-Open No. 2001-170547 discloses a configuration in which a dry dryer is provided immediately after coating. Here, a method of suppressing the occurrence of unevenness is disclosed by dividing the drying dryer and blowing and drying the divided portions from one end side in the width direction of the support body to the other end side while controlling the wind speed. Yes. Japanese Patent Laid-Open No. 9-73016 discloses a method of installing a wire mesh instead of dividing a dryer for the same purpose.
[0008]
Japanese Patent Laid-Open No. 2001-170547 discloses that the viscosity of a coating solution is increased by increasing the concentration of the coating solution or adding a thickener to the coating solution. There are disclosed a method for suppressing the flow due to the above, and a method for preventing the occurrence of unevenness due to the leveling effect even when the flow of the coating film surface immediately after coating is caused by the drying air by using a high boiling point solution.
[0009]
However, the methods disclosed in JP-A-2001-170547 and JP-A-9-73016 are effective in suppressing the inflow of non-uniform wind from the outside of the dryer, but when the wind speed is controlled so as not to disturb the coating film surface. It is necessary to greatly reduce the wind speed. As a result, the drying speed is greatly reduced, and it is necessary to increase the length of the drying dryer to cope with it. Therefore, the coating efficiency is deteriorated. Still, it is difficult to completely eliminate the influence of wind.
[0010]
In addition, the method of increasing the viscosity of the coating solution or using a high-boiling point solution, as described in Japanese Patent Laid-Open No. 2001-170547, eliminates the suitability for high-speed coating and increases the drying time. There was a problem that became extremely worse.
[0011]
Thus, in the ventilation drying method, particularly in the ventilation drying method in the case where the coating liquid contains an organic solvent, the coating surface is dried unevenly in the initial stage of drying, and therefore the method of drying without blowing air is GB1401041 , US5168639, US5694701 and the like.
[0012]
That is, GB1401041 discloses a method of evaporating, collecting and drying a solvent in a coating solution without blowing air. This method is a method in which the inlet and outlet of the support are provided at the upper part of the casing, the non-application surface is heated in the casing to promote the evaporation of the solvent from the application surface, and condensation is caused on the condensation plate installed on the application surface side. In this method, the solvent is condensed to recover the solvent and dry the coating film.
[0013]
US5168639 discloses a method for recovering a solvent using a drum on an upper part of a support that runs horizontally. Further, US5694701 proposes a layout improvement method of US5168639.
[0014]
[Problems to be solved by the invention]
However, in GB1401041, since the entrance and exit of the support are limited to the upper part of the casing, the layout of the apparatus is greatly restricted, and it is difficult to incorporate it into the existing coating process. In the example shown in Fig.5, it is necessary to have a certain distance before entering the recovery dryer after coating, and it is necessary to reverse the base before entering the recovery dryer. It is difficult to suppress well.
[0015]
In US5168639, since the distance from the coating surface to the condensation / solvent recovery drum varies depending on the coating direction, it is difficult to uniformly control the drying speed over the entire area of the casing. Since the distance between the surface and the condensation / cooling drum is unnecessarily large, another coating unevenness occurs due to the occurrence of natural convection.
[0016]
In the method of improving the layout of US5168639, it is difficult to adopt a configuration in which the distance from the coating device to the condensation / solvent recovery device is close, and this is insufficient to prevent coating unevenness.
[0017]
Further, in the conventional solvent condensation / recovery method, the installation position of the condenser, the heating device, etc. in the condensation / recovery device, the set temperature, etc. are made constant, and the solvent is uniformly evaporated / recovered in the device. For this reason, it is convenient to set the same drying speed over the entire area in the apparatus, but it is not possible to select and dry the optimum conditions at each stage of the initial stage, middle stage, and late stage of drying. That is, it is difficult to control optimum conditions for suppressing coating unevenness, to control fine dry film quality, and to make drying efficient throughout the entire process.
[0018]
For example, in order to increase the drying speed, it is necessary to reduce the distance between the condensing surface of the apparatus and the coating film, but it is easily affected by the set distance accuracy. In addition, when the distance accuracy is improved, the manufacturing cost of the apparatus is generally greatly increased, which is not desirable.
[0019]
In addition, when it is desired to dry uniformly and quickly only in the initial stage of drying, the conventional method reduces the distance between the condensing surface of the device and the coating film over the entire length of the condensing / recovery zone. There was a considerable increase in costs.
[0020]
On the other hand, in order to keep the drying speed at the initial stage of drying low, it is necessary to lower the drying efficiency of the entire condensation / recovery zone. In this case, there is a problem that the total length of the condensation / recovery zone has to be increased.
[0021]
The present invention has been made in view of such circumstances, and in a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support, immediately after coating. An object of the present invention is to provide a method and apparatus for drying a coating film that suppresses uneven drying and efficiently dries.
[0022]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention provides a dryer for applying a coating solution to a traveling belt-like flexible support by coating means and condensing and recovering the solvent in the coating solution at a running position immediately after coating. In the method for drying a coating film, a condensing plate, which is a plate member, is disposed substantially parallel to the belt-like flexible support at a predetermined distance, and the condenser plate and the belt-like flexible support are disposed on the dryer. The distance from the body is changed in the traveling direction of the belt-like flexible support.
[0023]
According to the present invention, in a method of drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support, the solvent of the coating solution is added immediately after the coating means. A condensing / recovering dryer is disposed, and a condensing plate, which is a plate member, is disposed substantially parallel to the strip-shaped flexible support body at a predetermined distance, and the condensing plate and the strip-shaped flexible are disposed in the dryer. By changing the distance from the conductive support in the running direction of the belt-like flexible support, drying unevenness that tends to occur immediately after coating can be suppressed and the drying can be performed efficiently.
[0024]
In particular, when the organic solvent is contained in the coating solution, or when the solvent of the coating solution is entirely composed of the organic solvent, the effect is great.
[0025]
The present invention is characterized in that the coating solution contains 3% by mass or more of an organic solvent. In this case as well, by applying the present invention, drying unevenness that occurs immediately after coating can be suppressed and drying can be performed efficiently.
[0026]
The organic solvent means an organic compound having a property of dissolving a substance, such as aromatic hydrocarbons such as toluene, xylene and styrene, chlorinated aromatic hydrocarbons such as chlorobenzene and orthodichlorobenzene, and monochloro. Methane derivatives such as methane, chlorinated aliphatic hydrocarbons containing ethane derivatives such as monochloroethane, alcohols such as methanol, isopropyl alcohol and isobutyl alcohol, esters such as methyl acetate and ethyl acetate, ethyl ether, 1,4 -Ethers such as dioxane, ketones such as acetone and methyl ethyl ketone, glycol ethers such as ethylene glycol monomethyl ether, alicyclic hydrocarbons such as cyclohexane, aliphatic hydrocarbons such as normal hexane, aliphatic or aromatic This includes hydrocarbon mixtures.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a coating film drying method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0028]
FIGS. 1-8 is a conceptual diagram which shows each example of the coating / drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied.
[0029]
As shown in the figure, the coating / drying line 10 mainly applies a feeding device (not shown) for feeding a strip-shaped flexible support 12 wound in a roll shape, and applies a coating solution to the strip-shaped flexible support 12. Coating means 16, a drying device comprising a dryer 18 for condensing and recovering the solvent in the coating liquid of the coating film formed on the belt-like flexible support 12, and winding for winding up the product produced by coating and drying A take-off device (not shown) and a large number of guide rollers 22, 22... That form a conveyance path along which the belt-like flexible support 12 travels.
[0030]
As the belt-like flexible support 12, a resin film such as polyethylene, PET (polyethylene terephthalate), TAC (triacetate), paper, metal foil, or the like can be used.
[0031]
Various types of coating means 16 can be used. For example, a slot die coater (see FIGS. 1, 5, and 7), a wire bar coater (see FIGS. 2, 4, and 8), a roll coater, a gravure coater (see FIG. 6), and a slide hopper coating system (see FIG. 3). See), curtain coating method, etc. can be used.
[0032]
The application means 16 may be configured such that the application surface is on the upper side with respect to the horizontal direction as shown in FIGS. 1, 3, 5, and 7, or FIG. As shown in FIG. 6 and FIG. 8, the configuration may be a lower side with respect to the horizontal direction. Moreover, the structure which inclines with respect to a horizontal direction may be sufficient.
[0033]
As shown in FIG. 9, a dust removal facility 70 may be installed in front of the application unit 16, or the surface of the belt-like flexible support 12 may be pretreated. For optical films and the like that require high quality with almost no dust, a high-quality coated and dried film can be obtained by simultaneously adopting these.
[0034]
The dryer 18 includes a condensing plate 20 which is a plate-like member provided substantially parallel to the belt-like flexible support 12 at a predetermined distance, and a side plate or the like suspended downward from the front and rear sides of the condensing plate 20. Composed. Thereby, when the solvent in the coating liquid of the coating film is volatilized, the volatilized solvent is condensed on the condenser plate 20 and collected.
[0035]
The material used for the surface of the condenser plate 20 on which the solvent is condensed is not particularly limited, such as metal, plastic, wood, etc., but when the coating solution contains an organic solvent, the material is resistant to the organic solvent. It is desirable to use a coating on the surface.
[0036]
In the dryer 18, the means for recovering the solvent condensed on the condensing plate 30, for example, provides a groove on the condensing surface of the condensing plate 30 and recovers the solvent using capillary force. The direction of the groove may be the traveling direction of the belt-like flexible support 12 or may be a direction orthogonal to this. When the condensing plate 30 is inclined, the grooves may be provided in a direction in which the solvent can be easily recovered.
[0037]
In the example shown in FIG. 10, a bowl 30a for collecting the condensed solvent is provided below the right end of the condenser plate 30, and the solvent is collected through the bowl 30a.
[0038]
In addition to the configuration in which the condensing plate 20 that is a plate-like member is employed for the dryer 18, a configuration that exhibits the same function, for example, a configuration that uses a perforated plate, a net, a scissors, a roll, or the like can also be employed. Further, it may be used in combination with a recovery device as shown in US5694701.
[0039]
The dryer 18 is provided with a condensing plate 20 that is a plate-like member substantially parallel to the belt-like flexible support 12 at a predetermined distance, and the distance between the condensing plate 20 and the belt-like flexible support 12. Can be changed in the traveling direction of the belt-like flexible support
As a structure which changes the distance of the condensation plate 20 and the strip | belt-shaped flexible support body 12 with the driving | running | working direction of a strip | belt-shaped flexible support body, as FIG. 1, FIG. 2 shows, several condensation plate 20, 20, Even when the distance between the condensing plate 20 and the strip-shaped flexible support 12 is changed stepwise, the condensing plate 20 is directed toward the running direction of the strip-shaped flexible support 12. A configuration in which the distance between the condensing plate 20 and the belt-like flexible support 12 is changed in a taper shape in the traveling direction of the belt-like flexible support 12 may be adopted (indicated not shown). In this case, the angle at which the condensing plate 20 is inclined toward the traveling direction of the strip-shaped flexible support 12 is preferably 30 degrees or less, more preferably 20 degrees or less with respect to the horizontal.
[0040]
In order to achieve the same effect as described above, the dryer 18 is provided with a plurality of condensing plates 20, 20, 20 along the traveling direction of the strip-shaped flexible support 12, and the condensing plates 20, 20 are separated from each other. 7 or a configuration in which partition plates 28, 28, 28 are disposed between the condensers 20, 20 as shown in FIG. 7, and a plurality of box-shaped dryers 18, 18, Either a configuration in which the condensing plates 20, 20, 20 are provided at 18 and the box-shaped dryers 18, 18 are in close contact with each other, or a configuration in which the dryers 18, 18 are separated from each other can be employed.
[0041]
The dryer 18 and the condensing plate 20 do not necessarily have a linear shape as shown in FIGS. 1, 2, etc. For example, the arc-shaped dryer 18 and the condensing plate 20 as shown in FIGS. There may be. Further, a large drum may be provided and a condensing plate may be provided.
[0042]
In the example shown in FIGS. 5 and 7, the arc-shaped dryer 18 and the condensing plate 20 are brought close to the coating means 16 to improve the solvent recovery efficiency.
[0043]
The dryer 18 is preferably arranged as close as possible to the coating means 16 in order to prevent uneven drying of the coating film due to the occurrence of natural convection immediately after the coating liquid is applied. Specifically, it is preferable to arrange the inlet of the dryer 18 so that it is located within 5 m from the coating means 16, and arrange so that the inlet of the dryer 18 is located within 2 m from the coating means 16. It is more preferable that the inlet of the dryer 18 is disposed so as to be located within 0.7 m from the coating means 16.
[0044]
For the same reason, the running speed of the strip-shaped flexible support 12 is preferably a speed at which the strip-shaped flexible support 12 reaches the dryer 18 within 30 seconds after coating by the coating means 16. It is more preferable that the support 12 has a speed that reaches the dryer 18 within 20 seconds after coating by the coating means 16.
[0045]
The larger the coating amount and the coating thickness of the coating solution, the more easily the unevenness occurs because the flow within the coating film is more likely to occur. However, according to the present invention, even when the coating amount and the coating thickness are large, sufficient Effects can be obtained. If the thickness of the coating film is 0.001 to 0.08 mm, it can be dried uniformly and efficiently.
[0046]
If the running speed of the belt-like flexible support 12 is too high, the boundary layer near the coating film is disturbed by the accompanying wind, which adversely affects the coating film. Therefore, the traveling speed of the belt-like flexible support 12 is preferably set to 1 to 100 m / min, and more preferably set to 5 to 80 m / min.
[0047]
In order to promote evaporation and condensation of the solvent in the coating solution, it is preferable to heat the belt-like flexible support 12 and / or the coating film, cool the condensation plate 20, or both. For example, cooling means (not shown) is disposed in the dryer, and heating means 24 and 24 are disposed on the opposite side of the dryer 18 with the belt-like flexible support 12 interposed therebetween (see FIGS. 4, 6, and 8). ).
[0048]
In any case, it is desirable that the temperature is controlled in order to control the drying rate of the coating film. The condenser plate 20 can be controlled in temperature, and if it is desired to cool, it is necessary to install equipment for cooling. For cooling, a water-cooled heat exchanger system using a refrigerant or the like, an air-cooled system using wind, a system using electricity, for example, a system using a Peltier element, or the like can be used.
[0049]
In the case where it is desired to heat the belt-like flexible support 12 and / or the coating film, a heater can be disposed on the anti-coating film side for heating. Moreover, it can also heat by arrange | positioning the conveyance roll (heating roll) which can be heated up. In addition, you may heat using an infrared heater, a microwave heating means, etc.
[0050]
When determining the temperature of the belt-like flexible support 12, the coating film, and the condensing plate 20, it should be noted that the evaporated solvent is condensed on a place other than the condensing plate 20, for example, on the surface of the transport roll. It is something that must be avoided. For this reason, this kind of dew condensation can be avoided by keeping the temperature of the part other than the condenser plate 20 higher than the temperature of the condenser plate 20, for example.
[0051]
The distance (interval) between the surface of the coating film and the surface of the condensing plate 20 of the dryer 18 needs to be adjusted to an appropriate distance in consideration of the drying speed of the desired coating film. Shortening the distance increases the drying speed, but is easily affected by the set distance accuracy. On the other hand, when the distance is increased, not only the drying speed is significantly reduced, but also natural convection due to heat occurs, resulting in drying unevenness. The distance between the surface of the coating film and the surface of the condenser plate 20 of the dryer 18 is preferably 0.1 to 200 mm, and more preferably 0.5 to 100 mm.
[0052]
Moreover, the structure which changes the preset temperature of the heating means 24 and 24 with the running direction of the strip | belt-shaped flexible support body 12 can also be taken. For example, in FIGS. 4, 6, etc., the set temperature of the upstream heating means 24 is made lower than the set temperature of the downstream heating means 24 in the traveling direction of the belt-like flexible support 12. By setting in this way, drying unevenness can be further suppressed.
[0053]
Similarly, the structure which changes the preset temperature of the cooling means of the dryer 18 with the running direction of a strip | belt-shaped flexible support body can also be taken. In FIG. 4, FIG. 6, etc., the set temperature of the cooling means of the upstream dryer 18 in the traveling direction of the belt-like flexible support 12 is made different from the set temperature of the downstream cooling means. 4 and 6 are combined with a configuration in which a plurality of condensing plates 20, 20, 20 are disposed and the distance between the condensing plate 20 and the strip-shaped flexible support 12 is changed stepwise. ing.
[0054]
In addition, various modes such as a configuration in which the set temperature of the heating units 24, 24 is changed stepwise, a configuration in which the set temperature of the cooling unit of the dryer 18 is changed stepwise, or a combination of these can be adopted.
[0055]
It should be noted that conventional members are used for the feeding device, the guide roller 22, the winding device, etc. used in the coating / drying line 10 incorporating the drying device to which the coating film drying method and apparatus of the present invention is applied. These descriptions are omitted.
[0056]
According to the coating film drying apparatus of the present invention described in detail above, the coating film can be efficiently and uniformly dried while suppressing unevenness occurring in the coating film immediately after coating. In addition, the layout of the coating and drying process is not greatly changed, and further, the physical properties of the coating liquid and the type of solvent are not restricted, so that the coating liquid prescription means can be designed flexibly.
[0057]
That is, for example, by simply adding a dryer for condensing and recovering the solvent between the coating unit of the coating / drying apparatus including the existing ventilation drying apparatus and the ventilation drying apparatus, the configuration similar to that of the apparatus of the present invention can be obtained. As a result, the device can be modified at low cost.
[0058]
Further, the coating film drying apparatus of the present invention is effective in energy saving and cost reduction. That is, since the solvent other than water cannot be released into the atmosphere as it is in the evaporation gas generated in the coating / drying line, the evaporation gas needs to be liquefied and recovered, and a solvent gas recovery facility for that purpose is required. However, in the coating / drying line 10, the solvent can be directly recovered in a liquid state by a dryer that condenses and recovers a part of the coating liquid, so that the load on the solvent gas recovery facility can be reduced.
[0059]
When the coating film drying apparatus of the present invention is used in combination with a ventilation drying apparatus, the blower equipment for blowing wind can be greatly reduced. Therefore, costs such as air conditioning equipment costs can be greatly reduced, and the equipment can be made very compact.
[0060]
Further, it was found that when the coating film drying apparatus of the present invention was used, extremely uniform drying was possible in the initial stage of drying, and the following unexpected effects were obtained. That is, in the conventional ventilation drying apparatus, since the influence that disturbs the coating film cannot be completely suppressed, the flow is generated in the coating film. However, when the apparatus of the present invention is used, the flow can be prevented, and It has been found that the polymer and particle network structure in the coating film formed during drying can be formed very finely and uniformly.
[0061]
As a result, the coating film is not only dried uniformly, but also the structure of the coating film becomes finer. For example, in the case of an optical film, a new additional function can be added.
[0062]
Moreover, it can be said that the drying apparatus of the coating film of this invention is very suitable for the drying of the functional film | membrane containing a nanoparticle etc., for example.
[0063]
Even when the coating film drying apparatus of the present invention is applied to a coating solution in which a solid content such as a polymer or particles is dissolved or dispersed, the same effect can be obtained. Rather, in a system containing particles or the like, the occurrence of drying unevenness greatly affects the dispersion distribution of particles in the coating film. Therefore, it is preferable to use this system in this system.
[0064]
【Example】
[Example 1]
A dryer 18 for condensing and recovering the solvent in the coating liquid is disposed in the coating layer drying process in the optical compensation sheet production line shown in FIG. 9 to provide a suitable dryer for producing the optical compensation sheet. The structure and solvent condensation and recovery conditions were studied.
[0065]
As shown in FIG. 9, the optical compensation sheet production line is performed, for example, by the following steps.
1) Delivery process 50 of the transparent film 12;
2) A forming step 52 of an alignment film forming resin layer in which a coating liquid containing an alignment film forming resin is applied to the surface of the transparent film and dried;
3) A rubbing step 54 in which an alignment film is formed on the transparent film by applying a rubbing treatment to the surface of the resin layer on the transparent film having the alignment film forming resin layer formed on the surface;
4) A liquid crystal discotic compound coating step 16 in which a coating liquid containing a liquid crystal discotic compound is coated on the alignment film;
5) A drying step 18 of drying the coating film and evaporating the solvent in the coating film;
6) A liquid crystal layer forming step 58 for heating the coating film to a discotic nematic phase forming temperature to form a discotic nematic phase liquid crystal layer;
7) The liquid crystal layer is solidified (that is, solidified by rapid cooling after the liquid crystal layer is formed, or when a liquid crystal discotic compound having a crosslinkable functional group is used, the liquid crystal layer is irradiated with light (or heated). Crosslinking) step 60;
8) A winding step 24 for winding the transparent film on which the alignment film and the liquid crystal layer are formed.
[0066]
In FIG. 9, 62 indicates a drying zone, 64 indicates an inspection device, 66 indicates a protective film, 68 indicates a laminating machine, and 70 indicates a slow dust facility.
[0067]
As shown in FIG. 3, the method for producing the optical compensation sheet was continuously performed continuously from the step of feeding the long transparent film to the step of winding up the obtained optical compensation sheet. On one side of a long film of triacetylcellulose (Fujitack, manufactured by Fuji Photo Film Co., Ltd., thickness: 100 μm, width: 500 mm), a long-chain alkyl-modified poval (MP-203, manufactured by Kuraray Co., Ltd.) ) A 5 wt% solution was applied and dried at 90 ° C. for 4 minutes, followed by rubbing to form an alignment film forming resin layer having a thickness of 2.0 μm. The conveyance speed of the film was 20 m / min.
[0068]
The triacetyl cellulose film has (nx−ny) × d, where nx and ny are the refractive indexes in two orthogonal directions in the film plane, nz is the refractive index in the thickness direction, and d is the thickness of the film. = 16 nm, {(nx-ny) / 2-nz} × d = 75 nm. The alignment layer forming resin layer was formed using a coating / drying apparatus.
[0069]
Subsequently, the surface of the resin layer was rubbed while the film having the obtained resin layer was continuously conveyed at 20 m / min. In the rubbing treatment, the rubbing roller was rotated at 300 rpm, and then the resulting alignment film was dedusted.
[0070]
Next, the weight of the discotic compound TE-8 (3) and the weight of TE-8 (5) is transferred onto the alignment film while continuously transporting the obtained film having the alignment film at a speed of 20 m / min. A 10% by weight methyl ethyl ketone solution (coating solution) of a mixture obtained by adding 1% by weight of a photopolymerization initiator (Irgacure 907, manufactured by Nippon Ciba Geigy Co., Ltd.) to the above mixture in a ratio of 4: 1 by With a coating machine, the coating speed is 20 m / min and the coating amount is 5 cc / m. ² And then passed through a drying and heating zone. Air was sent to the drying zone, and the heating zone was adjusted to 130 ° C. After 3 seconds from coating, it entered the drying zone, and after 3 seconds, it entered the heating zone. The heating zone passed in about 3 minutes.
[0071]
Subsequently, the alignment film and the liquid crystal layer were applied, and the surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp while the film was continuously conveyed at 20 m / min. That is, the film that passed through the heating zone was irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) to crosslink the liquid crystal layer.
[0072]
The test was performed under the above-described process under six conditions. The conditions and results are described below.
[0073]
(Test 1)
The heater temperature was 85 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condenser plate 20 of the dryer 18 was 3 mm.
[0074]
As a result, a travel distance of 6 m was required to completely dry the coating film. There was no problem in coating film quality.
[0075]
(Test 2)
The heater temperature was 85 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 0.5 mm.
[0076]
As a result, a travel distance of 1 m was required to dry the coating film. In the coating film, uneven drying occurred in the width direction, and alignment failure occurred.
[0077]
(Test 3)
The heater temperature was 85 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The condenser plate 20 was divided into three zones. The three condenser plates 20 were all arranged with an inclination angle of 5 degrees so that the downstream side in the running direction was separated from the coating film. The distance between the surface of the coating film and the surface of the condensing plate 20 of the dryer 18 was 3 mm, 1.5 mm, and 0.5 mm, respectively, toward the downstream side in the traveling direction of the three condensing plates 20.
[0078]
As a result, a travel distance of 1.8 m was required to completely dry the coating film. There was no problem in coating film quality. That is, under these conditions, it was possible to achieve both shortening of the process length and good coating film quality.
[0079]
(Test 4)
The heater temperature was 60 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 1 mm.
[0080]
As a result, a travel distance of 5 m was required to completely dry the coating film. There was no problem in coating film quality.
[0081]
(Test 5)
The heater temperature was 60 ° C. and the condenser plate temperature was 15 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 1 mm.
[0082]
As a result, a travel distance of 2 m was required to completely dry the coating film. In the coating film, uneven drying occurred in the width direction, and alignment failure occurred.
[0083]
(Test 6)
The heater temperature was 60 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The condenser plate 20 was divided into three zones. Moreover, the condensing plate temperature of the three condensing plates 20 was 25 degreeC, 20 degreeC, and 15 degreeC, respectively toward the downstream of the running direction. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 1 mm.
[0084]
As a result, a travel distance of 0.8 m was required to completely dry the coating film. There was no problem in coating film quality. That is, under these conditions, it was possible to achieve both shortening of the process length and good coating film quality.
[0085]
[Example 2]
In the drying process after the undercoat coating in the photosensitive cellulose acetate film production line, a dryer for condensing and recovering the solvent in the coating liquid in the present invention is disposed, and a conventional ventilation drying type dryer is disposed. The case was compared.
[0086]
In the production line using the dryer of the present invention shown in FIG. 10, the cellulose acetate dope is cast from the casting die onto the casting drum surface, and the film formed thereby is peeled off by the peeling roller. It is dried with hot air while traveling between the rolls in the pre-drying step.
[0087]
Next, an undercoat for a photographic light-sensitive material is applied and further dried with a dryer 18. When the residual solvent becomes about 10% or less, it is guided to a width regulating device (not shown), stretched in the width direction by 2 to 6%, and further cooled in a tension state and then wound up.
[0088]
The condenser plate 20 of the dryer 18 was divided into two zones. Further, the two condensing plates 20 were arranged at an inclination angle such that the downstream side in the traveling direction was separated from the coating film. The distance between the surface of the coating film and the surface of the condensing plate 20 of the dryer 18 is 0.8 mm on the inlet side of the condensing plate 20 on the upstream side and 2 mm on the outlet side toward the downstream side in the traveling direction. The plate 20 was 0.8 mm on the inlet side and 2 mm on the outlet side.
[0089]
Further, the length of the upstream condenser plate 20 was 2 m, and the length of the downstream condenser plate 20 was 4 m. The set temperature of the condenser plate 20 was 15 ° C. for all.
[0090]
The surface quality of the manufactured product was good.
[0091]
In the production line using the conventional ventilation drying type dryer shown in FIG. 11, the apparatus of the undercoat coating drying process is a normal ventilation drying type dryer. The other parts of the production line are the same as those shown in FIG.
[0092]
The surface properties of the manufactured product were poor due to uneven drying in the undercoat.
[0093]
[Example 3]
Example in which drying means in combination with drying / condensing dryer (front stage side) and ventilation drying means (rear stage side) is disposed in the drying process of the photothermographic material production line, and conventional ventilation drying type This was compared with a comparative example in which only the drying means was provided.
[0094]
A coating solution for the photothermographic material to be coated on the belt-like flexible support was prepared as follows.
[0095]
1) Preparation of silver halide grains
After dissolving 22 g of phthalated gelatin and 30 mg of potassium bromide in 700 ml of water and adjusting the pH to 5 at a temperature of 35 ° C., 159 ml of an aqueous solution containing 18.6 g of silver nitrate, 92 ml of potassium bromide and potassium iodide were added. An aqueous solution containing a molar ratio of 8 was added over 10 minutes by the control double jet method while maintaining pAg 7.7. Next, a control double jet method is used while maintaining 476 ml of an aqueous solution containing 55.4 g of silver nitrate, 10.5 μmol / liter of dipotassium hexachloroiridate, and an aqueous solution pAg7.7 containing 1 mol / liter of potassium bromide. Added over 30 minutes. Thereafter, the pH is lowered to agglomerate and precipitate for desalting treatment, 0.11 g of phenoxyethanol is added to adjust the pH to 5.9, pAg 8.2, silver iodobromide grains (iodine content core 8 mol%, average 2 mol%) And cubic grains having an average size of 0.05 μm, a projected area variation coefficient of 8%, and a (100) plane ratio of 90%).
[0096]
The silver halide grains thus obtained were heated to 60 ° C. and 85 μmol of sodium thiosulfate per mole of silver and 11 μmol and 15 μmol of 2,3,4,5,6 pentafluorophenyldiphenylphosphine selenide. A tellurium compound, 3.6 μmol of chloroauric acid, and 280 μmol of thiocyanic acid were added and ripened for 120 minutes, and then rapidly cooled to 30 ° C. to obtain a silver halide emulsion.
[0097]
2) Preparation of organic acid silver emulsion
1.3 g of stearic acid, 0.5 g of arachidic acid, 8.5 g of behenic acid, and 300 ml of distilled water were mixed at 90 ° C. for 40 minutes, and 31.1 ml of 1N sodium hydroxide aqueous solution was stirred for 15 minutes while stirring vigorously. The temperature was raised to 30 ° C. Next, 7 ml of 1N phosphoric acid aqueous solution is added, 0.012 g of N-bromosuccinimide is added while stirring more vigorously, and the silver halide amount of the silver halide grains prepared in advance becomes 2.5 mmol. Was added as follows. Further, 25 ml of 1N aqueous silver nitrate solution was added over 25 minutes, and stirring was continued for 90 minutes. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water until the conductivity of the filtrate became 30 μS · cm. 37 g of a 1.2% by weight butyl acetate solution of polyvinyl acetate was added to the solid content thus obtained and stirred. The stirring was stopped and the mixture was allowed to stand to separate into an oil layer and an aqueous layer, and the aqueous layer was removed together with the contained salt An oil layer was obtained. Next, 20 g of a 2.5 wt% 2-butanone solution of polyvinyl butyral was added to the oil layer and stirred. Further, 0.1 mmol of pyridinium perbromide and 0.18 mmol of calcium bromide dihydrate were added together with 0.7 g of methanol, and then 40 g of 2-butanone and 7.8 g of polyvinyl tyral were added to form a homogenizer. To obtain an organic acid silver salt emulsion (acicular grains having an average minor axis of 0.04 μm, an average major axis of 1 μm, and a variation coefficient of 30%).
[0098]
3) Preparation of emulsion layer coating solution
Each chemical | medical agent was added to the organic acid silver salt obtained above so that it might become the following quantity per 1 mol of silver. 10 mg sodium phenylthiosulfonate at 25 ° C., 68 mg dye 1, 30 mg dye 2, 2-mercapto-5-methylbenzimidazole 2 g, 4-chlorobenzophenone-2-carboxylic acid 21.5 g, 2-butanone 580 g, 220 g of dimethylformamide was added with stirring and left for 3 hours. Subsequently, 8 g of 5-tribromomethylsulfonyl-2-methylthiadiazole, 6 g of 2-tribromomethylsulfonylbenzothiazole, 5 g of 4,6-ditrichloromethyl-2-phenyltriazine, 2 g of a disulfide compound, 1,1-bis (2 -Hydroxy-3,5-dimethylphenyl) -3,5,5 trimethylhexane 160 g, tetrachlorophthalic acid 5 g, 1.1 g of fluorosurfactant, 2-butanone 590 g, methyl isobutyl ketone 10 g added with stirring did.
[0099]
The emulsion layer coating solution prepared as described above was tinted with a blue dye and a 175 μm polyethylene terephthalate support (band-like flexible support) had 2.3 g / cm of silver. ² It applied so that it might become. Then, after application, in the case of Examples, it was dried with a condensing / collecting dryer (front side) and ventilation drying means (back side), and then irradiated with ultraviolet rays to obtain a photothermographic material. On the other hand, in the case of the comparative example, the coating film was dried only with a ventilation drying type dryer, and then irradiated with ultraviolet rays to obtain a photothermographic material.
[0100]
The surface quality of the product produced by the method of the example was good. On the other hand, the surface property of the product manufactured by the method of the comparative example was poor due to the influence of wind unevenness.
[0101]
[Example 4]
In the drying process of the hard coat film production line, an example in which a drying means combining a dryer that condenses and collects (front stage side) and a ventilation drying means (rear stage side) is disposed, and a conventional ventilation drying type This was compared with a comparative example in which only the drying means was provided.
[0102]
A hard coat coating solution to be applied to the belt-like flexible support was prepared as follows.
1) Preparation of inorganic particle dispersion (M-1)
The following reagents were blended in the following blending amounts in a ceramic-coated container to prepare a mixed solution.
[0103]
・ Cyclohexane… 337g
・ Phosphate group-containing methacrylate (PM-2: Nippon Kayaku) ... 31g
Alumina (AKP-G015: manufactured by Sumitomo Chemical Co., Ltd., particle size 15 nm) ... 92 g
The obtained mixture was finely dispersed in a sand mill (1/4 G sand mill) at 1600 rpm for 10 hours. As a medium, 1400 g of 1 mmφ zirconia beads was used. After dispersion, zirconia beads were separated to obtain a surface-modified inorganic particle dispersion (M-1).
[0104]
2) Preparation of coating solution for active energy ray cured layer
97 g of methanol, 163 g of isopropanol, and 163 g of methyl isobutyl ketone were added to 116 g of 43 wt% cyclohexane dispersion (M-1) of the surface-treated alumina fine particles. 200 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) was added to this mixed solution and dissolved. Further, 7.5 g of a photopolymerization initiator (Irgacure 184, manufactured by Ciba Geigy) was added and dissolved. The mixture was stirred for 30 minutes and then filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating solution for an active energy ray cured layer.
[0105]
3) After the band-like flexible support (base film) was subjected to glow discharge treatment, the coating solution for active energy ray cured layer containing alumina was applied by a wire bar coating means so that the dry film thickness was 8 μm. And after application | coating, after drying with the dryer (front stage side) and ventilation drying means (back stage side) which condense and collect | recover in the case of an Example, the ultraviolet-ray irradiation was performed and the hardened layer was obtained. On the other hand, in the case of the comparative example, the coating film was dried only by a ventilation drying type dryer, and then irradiated with ultraviolet rays to obtain a cured layer.
[0106]
Next, in the drying process of the production line of the thick hard coat film, an example in which drying means that combines a dryer that condenses and collects (front stage side) and ventilation drying means (rear stage side) is disposed, and conventional This was compared with a comparative example in which only a ventilation drying type drying means was provided.
[0107]
A thick film hard coat coating solution to be applied to the belt-like flexible support was prepared as follows.
[0108]
1) Preparation of ring-opening polymerizable group-containing compound (K-1)
After stirring 275 ml of methyl ethyl ketone (MEK) at 60 ° C. for 1 hour under a nitrogen stream, a total amount of 0.5 g of a polymerization initiator (V-65: manufactured by Wako Pure Chemical Industries) dissolved in 8.3 ml of MEK was added. A polymerization initiator addition solution was prepared. Thereafter, 50 g of glycidyl methacrylate was added dropwise over 2 hours, and after completion of the addition, the prepared polymerization initiator addition solution was added and reacted for 2 hours. Thereafter, the reaction was carried out at a reaction temperature of 80 ° C. for 2 hours, and after completion of the reaction, it was cooled to room temperature. The obtained reaction solution was added dropwise to 10 liters of hexane over 1 hour, and the precipitate was dried under reduced pressure at 35 ° C. for 8 hours to obtain a ring-opening polymerizable group-containing compound (K-1).
[0109]
2) Preparation of curable composition
75 parts of trimethylolpropane triacrylate (ethylenically unsaturated group-containing compound), 25 parts of the prepared ring-opening polymerizable group-containing compound (K-1), a radical polymerization initiator (Irgacure 184, manufactured by Ciba Geigy) Then, a cationic polymerization initiator (UVI-6990: Union Carbide Japan Co., Ltd.) was dissolved in 40 parts of a methyl isobutyl ketone / methyl ethyl ketone (1/5) mixed solution and stirred for 30 minutes to obtain a curable composition. In addition, the polymerization initiator added 2.9 weight% of radical polymerization initiators and cationic polymerization initiators with respect to the total mass of the ethylenically unsaturated group-containing compound and the ring-opening polymerizable group-containing compound.
[0110]
3) As a transparent belt-like flexible support (transparent substrate film), a polyethylene terephthalate film having a thickness of 188 μm was subjected to glow discharge treatment, and then the prepared curable composition was applied by an extrusion type coating method. Then, after application, in the case of the examples, after drying with a dryer to be condensed / recovered (front stage side) and ventilation drying means (back stage side), UV irradiation is performed and heating is further performed at 120 ° C. for 10 minutes. A membrane hard coat film was obtained. On the other hand, in the case of the comparative example, the coating film was dried only with a ventilation drying type dryer, then irradiated with ultraviolet light, and further heated at 120 ° C. for 10 minutes to obtain a thick hard coat film. Drying is performed at 120 ° C. for 2 minutes, and ultraviolet irradiation is 750 mj / cm. ² It went on condition of.
[0111]
The surface quality of the product produced by the method of the example was good. On the other hand, the surface texture of the product manufactured by the method of the comparative example caused a thickness unevenness that seems to be an influence of wind unevenness and became defective.
[0112]
【The invention's effect】
According to the coating film drying method and apparatus of the present invention, drying occurs immediately after coating on a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support. The coating film can be dried uniformly while suppressing unevenness.
[0113]
In addition, the layout of the coating and drying process is not greatly changed, and further, the physical properties of the coating liquid and the type of solvent are not restricted, so that the coating liquid prescription means can be designed flexibly. It is also effective for energy saving and cost reduction.
[0114]
Furthermore, the flow in the coating film can be prevented, and the structure of the polymer and particle network in the coating film formed during drying can be formed very finely and uniformly.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an example of a coating / drying line 10 incorporating a drying apparatus to which a coating film drying method and apparatus of the present invention are applied.
FIG. 2 is a conceptual diagram showing another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention is applied.
FIG. 3 is a conceptual diagram showing still another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention are applied.
FIG. 4 is a conceptual diagram showing still another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention are applied.
FIG. 5 is a conceptual diagram showing still another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention are applied.
6 is a conceptual diagram showing still another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention is applied. FIG.
FIG. 7 is a conceptual diagram showing still another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention are applied.
FIG. 8 is a conceptual diagram showing still another example of a coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus of the present invention are applied.
FIG. 9 is a conceptual diagram showing an example in which the coating film drying apparatus of the present invention is applied to an optical compensation sheet production line.
FIG. 10 is a conceptual diagram showing an example in which the coating film drying apparatus of the present invention is applied to a photosensitive cellulose acetate film production line.
FIG. 11 is a conceptual diagram showing an example in which a conventional drying type dryer is applied to a photosensitive cellulose acetate film production line.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Application | coating / drying line, 12 ... Strip | belt-shaped flexible support body, 16 ... Application | coating means, 18 ... Dryer, 20 ... Condensing plate, 22 ... Guide roller, 24 ... Heating means, 28 ... Partition plate

Claims

In the method for drying a coating film, a coating liquid is applied to a traveling belt-like flexible support by a coating means, and a dryer for condensing and collecting the solvent in the coating liquid is disposed at a traveling position immediately after coating.
The dryer is provided with a condensing plate that is a plate- like member at a predetermined distance from the strip-shaped flexible support, and the condensing plate is inclined at a predetermined angle toward the running direction of the strip-shaped flexible support. And a distance between the condensing plate and the strip-shaped flexible support is changed in a taper shape in the running direction of the strip-shaped flexible support .

A plurality of condensing plates are disposed in the dryer along the traveling direction of the belt-like flexible support, and the condensing plates are disposed apart from each other or a partition plate is disposed between the condensing plates. 2. A method for drying a coating film according to 1 .

The method for drying a coating film according to claim 1 or 2, wherein the coating solution contains 3% by mass or more of an organic solvent.

The method for drying a coating film according to any one of claims 1 to 3 , wherein a distance between the coating means and the dryer is 5 m or less.

The method for drying a coating film according to any one of claims 1 to 4 , wherein a distance between the coating unit and the dryer is 0.7 m or less.

Running speed of the belt-shaped flexible support, the coating film according to any one of claims 1 to 5 band-shaped flexible support is a speed reaching the dryer within 30 seconds after coating by the coating unit Drying method.

The coating film according to any one of claims 1 to 6 , wherein a running speed of the belt-like flexible support is a speed at which the belt-like flexible support reaches the dryer within 20 seconds after coating by the coating means. Drying method.

The drying method of the coating film according to claim 1 to 7 the thickness of the coating film is 0.001～0.08Mm.

The drying method of the coating film according to any one of the band-shaped flexible support according to claim 1-8 traveling speed is 1 to 100 m / min of.

The drying method of the coating film according to any one of the band-shaped flexible support according to claim 1-9 traveling speed is 5～80M / min of.

The drying method of the coating film in any one of Claims 1-10 which has arrange | positioned the cooling means to the said dryer.

The method for drying a coating film according to any one of claims 1 to 11 , wherein heating means is disposed on the opposite side of the dryer with the belt-like flexible support interposed therebetween.

The drying method of the coating film of Claim 12 which used the heating roll for the said heating means.

The method for drying a coating film according to claim 12 , wherein an infrared heater or a microwave heating unit is used as the heating unit.

The drying method of the coating film according to any one of claims 1-14 distance between the surface and the surface of the dryer of the coating film is 0.01～200Mm.

The drying method of the coating film according to any one of claims 1 to 15 the distance between the surface and the surface of the dryer of the coating film is 0.01～100Mm.

The drying method of the coating film in any one of Claims 12-16 which changes the preset temperature of the said heating means with the running direction of a strip | belt-shaped flexible support body.

The drying method of the coating film in any one of Claims 11-17 which changes the preset temperature of the cooling means of the said dryer with the running direction of a strip | belt-shaped flexible support body.

The method for drying a coating film according to claim 17 , wherein the set temperature of the heating means is changed stepwise.

The method for drying a coating film according to claim 18 , wherein the set temperature of the cooling means of the dryer is changed stepwise.

In an apparatus for drying a coating film, which is disposed in a subsequent stage following the coating means for coating the coating liquid on the traveling belt-like flexible support, and which condenses and recovers the solvent in the coated coating liquid.
The dryer is provided with a condensing plate that is a plate- like member at a predetermined distance from the strip-shaped flexible support, and the condensing plate is inclined at a predetermined angle toward the running direction of the strip-shaped flexible support. And a distance between the condensing plate and the belt-like flexible support is variable in a taper shape in the running direction of the belt-like flexible support .

Heating means is disposed on the opposite side of the dryer across the belt-like flexible support, and the set temperature of the heating means can be changed in the running direction of the belt-like flexible support. The coating film drying apparatus according to claim 21 .

Wherein the dryer are arranged cooling means, the drying apparatus of the coating film according to by that claim 21 or 22 so set temperature can be changed in the traveling direction of the belt-shaped flexible support of said cooling means .