JP3765271B2 - Release film with ceramic sheet - Google Patents

Description

【０１１８】
ここで、Ｚ＝ｆ（ｘ、ｙ）は、上記直交座標軸上の位置（ｘ、ｙ）におけるフィルム表面の高さＺを表す関数を意味し、Ｌx=５００、Ｌy=１５０である。
【０１１９】
また、Ｓλａは三次元空間平均波長であり、前記表面粗さ曲線の振幅を意味する。すなわち、中心面平均表面粗さが同じであれば、突起が急峻なほどＳλａは小さくなる。
【０１２０】
突起数ＰＣは、微分干渉顕微鏡（ニコン社製）を用いてアルミニウム蒸着したフィルムを最終倍率１６０倍で写真を撮り、透明なＯＨＰシートに突起をトレースして、ニレコ社製イメージアナライザー（Luzex IID）で、フィルム０．１２ｍｍ²に相当する面積を画像処理し、前記面積内の突起の個数を算出した。
【０１２１】
（７）剥離したセラミックシート面の平滑性
セラミックシート付き離型フィルムを５ｃｍ巾にカットし、セラミックシート層面にポリエステル粘着テープ（日東電工社製、ニットー３１Ｂ）を貼り、ピール法（剥離速度：５００ｍｍ／分、Ｔ型剥離）によりセラミックシート層を離型フィルムから剥離し、剥離したセラミックシート面を、微分干渉顕微鏡（ニコン社製）で２００倍で観察し、表面凹凸のないものを〇、表面凹凸のあるものを×とした。
【０１２２】
（８）セラミックシートのピンホール
セラミックシート付き離型フィルムを巾１００ｍｍ、長さ１ｍに切断した。トレーザートレース台（コクヨ社製）に、上面がセラミックシート面となるように前記セラミックシート付き離型フィルムを置き、下面から光をあてセラミックシート面から光が漏れる箇所の数を目視で数え、１ｍ²当たりの個数に換算し小数第１位の桁を四捨五入した。
○：１０個／ｍ²以下
△：２０〜５０個／ｍ²
×：６０個以上／ｍ²
【０１２３】
（実施例１）
撹拌装置、分縮器、原料仕込口及び生成物取り出し口を設けた２段の完全混合器よりなる連続エステル化反応装置を用い、その第一エステル化反応缶のエステル化反応生成物が存在する系へ、テレフタル酸に対するエチレングリコールのモル比率１．７に調整し、かつ三酸化アンチモンをアンチモン原子としてテレフタル酸単位あたり２８９ｐｐｍを含むエチレングリコールスラリーを連続的に供給した。
【０１２４】
同時にテレフタル酸のエチレングリコールスラリー供給口とは、別の供給口より、酢酸マグネシウム四水塩のエチレングリコール溶液を反応缶内を通過する反応生成物中のポリエステル単位ユニット当たりそれぞれＭｇ原子として１００ｐｐｍとなるように連続的に供給し、常圧にて平均滞留時間４．５時間、温度２５５℃で反応させた。
【０１２５】
この反応生成物を連続的に系外に取り出して、第２エステル化反応缶に供給した。第２エステル化反応缶内を通過する反応生成物中のポリエステルユニットに対して、０．５重量部のエチレングリコール、トリメチルホスフェイトのエチレングリコール溶液をＰ（リン）原子として６４ｐｐｍ、及び平均粒子径Ｄ₅₀（島津製作所製、ＳＡ−ＣＰ３）が０．９μｍで、Ｄ₅₀／Ｄ₅が０．４である炭酸カルシウムのエチレングリコールスラリーに１００ｇ／Ｌのトリポリリン酸ナトリウムの水溶液をＮａ原子としてスラリー中の炭酸カルシウムとして２５００ｐｐｍとなるようにそれぞれ別個の供給口より連続的に供給し、常圧にて平均滞留時間５時間、温度２６０℃で反応させた。
【０１２６】
該エステル化反応生成物を撹拌装置、分縮器、原料仕込口及び生成物取り出し口を設けた２段の連続重縮合反応装置に連続的に供給して重縮合を行い、固有粘度０．６２ｄｌ／ｇのポリエステルを得た。
【０１２７】
該ポリマーを２９０℃で溶融押し出しし、９０℃で縦方向に３．５倍、１３０℃で横方向に３．５倍延伸した後、２２０℃で熱処理して厚さ３８μｍの二軸延伸ポリエステルフィルムを製造し、ロール状に巻き取った。
【０１２８】
次に紫外線カチオン硬化型シリコーンレジン（東芝シリコン社製、ＵＶ９３１５）を溶剤（ノルマルヘキサン）中に樹脂固形分濃度が２重量％となるように分散し、シリコーンレジン１００重量部に対し、１重量部のビス（アルキルフェニル）ヨードニウムヘキサフルオロアンチモネートを硬化触媒として添加し、シリコーン樹脂を含む塗布液を作成した。
【０１２９】
厚さ３８μｍの上記二軸延伸ポリエステルフィルムロールを巻き出し、ワイヤーバーにて、上記シリコーン樹脂を含む塗布液をフィルムの片面に塗布し、１００℃×３０秒で乾燥後、紫外線照射装置で紫外線照射（３００ｍＪ／ｃｍ²）し、離型フィルム（シリコーン離型層の乾燥後の塗布量０．１０ｇ／ｍ²）を製造し、ロール状に巻き取った。
【０１３０】
また、溶剤（トルエン／エタノール＝５０／５０：重量比）中にセラミック粒子（平均一次粒子径が０．６μｍのチタン酸バリウム（ＢａＴｉＯ₃）、富士チタン社製）１００重量部を混合し、粒径１．５ｍｍのジルコニアビーズ（充填量：スラリーに対し２００重量％）とともにボールミルで２４時間分散した。次いで、バインダー（ポリビニルブチラール、積水化学工業社製）１０重量部及び可塑剤（ポリエチレングリコール）をセラミック粉末とバインダーの総量に対し２重量％混合し、ボールミルで２４時間分散し、さらにフィルター（孔径３μｍ）で濾過処理を行い、ペースト状のセラミックスラリーを得た。
【０１３１】
前記の離型フィルムロールを巻き出し、上記セラミックスラリーをドクターブレード法により離型フィルムの離型層面に塗布し、１２０℃で１分間乾燥して、厚みが３μｍのセラミックシート層（セラミック粒子／バインダー＝１００／１０：重量比）を積層したセラミックシート付き離型フィルムを得た。
【０１３２】
（実施例２）
熱硬化型シリコーンレジン（信越化学社製、ＫＳ８３０）を溶剤（トルエン）中に樹脂固形分濃度が３重量％となるように分散し、シリコーンレジン１００重量部に対し、１重量部の白金触媒を添加してシリコーン樹脂を含む塗布液を作成した。この塗布液を、ワイヤーバーにて実施例１の二軸延伸ポリエステルフィルムの片面に塗布し、１４０℃×３０秒で乾燥し、乾燥後の塗布量が０．０５ｇ／ｍ²の離型層を有する離型フィルムを製造し、ロール状に巻き取った。さらに、実施例１と同様にしてセラミックシート付き離型フィルムを得た。
【０１３３】
（実施例３）
実施例１において、炭酸カルシウム粒子の代わりに、平均粒子径Ｄ₅₀が２．４７μｍのシリカ粒子をポリエステルに６０ｐｐｍ含有させた以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１３４】
（比較例１）
実施例２において、離型層の乾燥後の塗布量を０．５ｇ／ｍ²としたこと以外は実施例２と同様にして、セラミックシート付き離型フィルムを得た。
【０１３５】
（比較例２）
実施例３において、セラミックシート層の厚みを２μｍにした以外は、実施例３と同様にして、セラミックシート付き離型フィルムを得た。
実施例１〜３及び比較例１、２で得られたセラミックシート付き離型フィルムの評価結果を表１に示す。
【０１３６】
【表１】

【０１３７】
実施例１、２、３は、それぞれセラミックシート表面のダイナミック硬度（Ａ）と離型層表面のダイナミック硬度（Ｂ）との関係が｜Ａ−Ｂ｜≦２０であり、セラミックシートの剥離不良は見られず、離型層の十点平均粗さＳＲｚは、セラミックシートの厚みの１／２以下であり、ピンホール欠点は発生しなかった。
【０１３８】
それに対し、比較例１は、ダイナミック硬度差｜Ａ−Ｂ｜が２０より大きく、セラミックの剥離不良が見られた。
【０１３９】
比較例２は、｜Ａ−Ｂ｜≦２０であったが、上記ＳＲｚがセラミックシートの厚みの１／２より大きく、セラミックシートにピンホール欠点が発生した。
【０１４０】
（実施例４）
二軸延伸ポリエチレンテレフタレートフィルムを次の方法で得た。エステル化反応缶を昇温し、２００℃に到達した時点で、テレフタル酸を８６．４重量部及びエチレングリコールを６４．４重量部からなるスラリーを仕込み、撹拌しながら触媒として三酸化アンチモンを０．０３重量部及び酢酸マグネシウム４水和物０．０８８重量部、トリエチルアミンを０．１６重量部添加した。次いで、加圧昇温を行いゲージ圧３．５ｋｇ／ｃｍ²、２４０℃の条件で、加圧エステル化反応を行った。その後、エステル化反応缶内を常圧に戻し、リン酸トリメチル０．０４０重量部添加した。さらに、２６０℃に昇温し、リン酸トリメチルを添加した。
【０１４１】
１５分後、得られたエステル化反応生成物を重縮合反応缶に移送し、２８０℃の減圧下で重縮合反応を行った。重縮合反応終了後、９５％カット径が２８μｍのナイロンフィルター（日本精線社製）で濾過処理を行い、固有粘度が０．６２ｄｌ／ｇのポリエチレンテレフタレートを得た。
【０１４２】
このポリエチレンテレフタレートを１３５℃で６時間減圧乾燥（１Ｔｏｒｒ）した後、押し出し機に供給し、約２８０℃でシート状に溶融押し出しして、表面温度２０℃に保った金属ロール上で急冷固化し、厚さ５３２μｍの未延伸ポリエステルフィルムを得た。この溶融押し出し工程で、溶融樹脂の異物除去用濾剤として濾材粒子サイズ（初期濾過効率９５％）が１５μｍのステンレス製焼結濾材を用いた。
【０１４３】
次に、この未延伸フィルムを加熱されたロール群及びＩＲヒーターで、１００℃に加熱し、その後周速差のあるロール群で長手方向に３．５倍延伸して一軸延伸ポリエステルフィルムを得た。引き続いて、ポリエステル共重合体（東洋紡績社製、ＭＤ１２００）５重量部、平均一次粒径０．０５μｍの二酸化珪素（ＳｉＯ₂）をポリエステル共重合体の重量に対して２５０００ｐｐｍ、水４７．５重量部、イソプロピルアルコール４７．５重量部からなる塗布液を前記一軸延伸フィルムの片面にコートし、７０℃の熱風で乾燥し、次いでフィルムの端部をクリップで把持して１３０℃に加熱された熱風ゾーンに導き、乾燥後巾方向に４．０倍に延伸し、その後２２０℃で熱処理し、厚さ３８μｍの片面に塗布層を有する二軸延伸ポリエステルフィルムを得た。
【０１４４】
カチオン型高分子帯電防止剤（商品名ケミスタット６３００Ｈ：三洋化成工業社製）０．２重量部、ポリエチレンワックス（商品名ハイテックＥ６０００：東邦化学工業社製）０．１重量部、メタノール５０重量部、水４９．７重量部を混合して塗布液を調整し、これを上記の方法により得られた片面に塗布層を有する二軸延伸ポリエチレンテレフタレートフィルム（厚み３８μｍ）のコート層上にワイヤーバーで、乾燥後の塗布量が０．０８ｇ／ｍ²となるように塗布し、９０℃×３０秒間熱風乾燥機中で乾燥した。
【０１４５】
次に、紫外線カチオン硬化型シリコーンレジン（東芝シリコン社製 ＵＶ９３１５）を溶剤（ノルマルヘキサン）中に樹脂固形分濃度が２重量％となるように分散し、シリコーンレジン１００重量部に対し、１重量部のビス（アルキルフェニル）ヨードニウムヘキサフルオロアンチモネートを硬化触媒として添加し、シリコーン樹脂を含む塗布液を作成した。厚さ３８μｍの上記帯電防止性ポリエステルフィルムの帯電防止層とは反対側の表面にワイヤーバーにて、上記シリコーン樹脂を含む塗布液を塗布し、１００℃×３０秒で乾燥後、紫外線照射装置で紫外線照射（３００ｍＪ／ｃｍ²）し、帯電防止層を有する離型フィルム（離型層の乾燥後塗布量：０．１０ｇ／ｍ²）を得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１４６】
（実施例５）
実施例４の帯電防止性ポリエステルフィルムの帯電防止層とは反対側の表面に熱硬化型シリコーンレジン（信越化学社製、ＫＳ８３０）を溶剤（トルエン）中に樹脂固形分濃度が３重量％となるように分散し、シリコーンレジン１００重量部に対し、１重量部の白金触媒を添加してシリコーン樹脂を含む塗布液を作成し、ワイヤーバーにて、フィルムの片面に塗布し、１４０℃×３０秒で乾燥し、離型帯電防止フィルム（シリコーン離型層の乾燥後塗布量０．０５ｇ／ｍ²）を得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１４７】
（実施例６）
紫外線照射量を５００ｍＪ／ｃｍ²となるようにした以外は、実施例４と同様にして、帯電防止層を有する離型フィルムを得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１４８】
（実施例７）
光透過型粒度分布測定装置（島津製作所製，ＳＡ−ＣＰ３）で測定した平均粒子径が０．６μｍの炭酸カルシウム粒子（丸尾カルシウム社製）をエチレングリコール中に仕込み、さらに９５％カット径が３０μｍのビスコースレーヨン製フィルターで濾過処理を行い、炭酸カルシウム粒子のエチレングリコールスラリーを得た。
【０１４９】
次に、エステル化反応缶を昇温し、２００℃に到達した時点で、テレフタル酸を８６．４重量部及びエチレングリコールを６４．４重量部からなるスラリーを仕込み、撹拌しながら触媒として三酸化アンチモンを０．０３重量部及び酢酸マグネシウム４水和物を０．０８８重量部、トリエチルアミンを０．１６重量部添加した。
【０１５０】
次いで、加圧昇温を行いゲージ圧３．５ｋｇ／ｃｍ²、２４０℃の条件で、加圧エステル化反応を行った。その後、エステル化反応缶内を常圧に戻し、リン酸トリメチル０．０４０重量部を添加した。さらに、２６０℃に昇温し、リン酸トリメチルを添加した１５分後に、上記炭酸カルシウム粒子のエチレングリコールスラリーを、生成ポリエステルに対し、１０００ｐｐｍとなるよう添加した。１５分後、得られたエステル化反応生成物を重縮合反応缶に移送し、２８０℃の減圧下で重縮合反応を行った。
【０１５１】
重縮合反応終了後、９５％カット径が２８μｍのナスロンフィルター（日本精線（株）製）で濾過処理を行い、固有粘度が０．６２ｄｌ／ｇの炭酸カルシウム粒子を含有するポリエチレンテレフタレートペレット（Ｂ）を得た。
【０１５２】
上記の炭酸カルシウム粒子を含有するポリエチレンテレフタレートペレット（Ｂ）と実施例４と同様の粒子を含有しないポリエチレンテレフタレートのペレット（Ａ）を１３５℃で６時間減圧乾燥（３Ｔｏｒｒ）した後、押し出し機１、押し出し機２にそれぞれ供給し、２８５℃で溶解した。
【０１５３】
この２つのポリマーを、それぞれステンレス焼結体の濾材（公称濾過精度：１０μｍ粒子９５％カット）で濾過し、矩形積層部を備えた２層合流ブロックにて、積層し、口金よりシート状にして押し出した後、静電印加キャスト法を用いて表面温度３０℃のキャスティングドラムに巻きつけて冷却固化し、未延伸フィルムを作った。この未延伸フィルムを加熱されたロール群とＩＲヒーターで１００℃に加熱し長手方向に３．５倍に延伸した。次いで、この一軸フィルムの端部をクリップで把持して１３０℃で加熱された熱風ゾーンに導き、巾方向に４．０倍に延伸し、２１０℃にて５秒間熱処理し、１３０℃で横方向に３％弛緩処理した。
【０１５４】
このようにして、炭酸カルシウム粒子１０００ｐｐｍを含有する厚み５μｍのポリエステル層の、粒子を含有していない厚み３３μｍのポリエステル層の積層二軸延伸ポリエステルフィルムを得た。
【０１５５】
次に、実施例４と同様の方法で、粒子を含有していないポリエステル層の表面に離型層を、炭酸カルシウム粒子を含有するポリエステル層の表面に帯電防止層を設けて、帯電防止層と離型層を別々の表面に有する積層二軸延伸ポリエステルフィルムを得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１５６】
（比較例３）
付加重合反応型シリコーンレジン（信越化学社製、ＫＳ８３０）を溶剤（トルエン）中に樹脂固形分濃度が３重量％となるように分散し、シリコーンレジン１００重量部に対し、１重量部の白金触媒を添加してシリコーン樹脂を含む塗布液を作成した。次に、平均粒径が１．０μｍの凝集体シリカ粒子を２００ｐｐｍ含有する、厚さ３８μｍの二軸延伸ポリエステルフィルムにワイヤーバーにて、上記シリコーン樹脂を含む塗布液をフィルムの片面に塗布し、１４０℃×３０秒で、反応硬化及び乾燥させ、離型フィルム（離型層の乾燥後塗布量：０．０５ｇ／ｍ²）を得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１５７】
（比較例４）
紫外線照射量を１００ｍJ／ｃｍ²となるようにした以外は、実施例４と同様にして、帯電防止層を有する離型フィルムを得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１５８】
（比較例５）
離型層の乾燥塗布量を０．５ｇ／ｍ²となるようにした以外は、実施例５と同様にして帯電防止層を有する離型フィルムを得た。次いで、セラミックシート層の厚みを２μｍにする以外は、実施例１と同様にして、セラミックシート付き離型フィルムを得た。
【０１５９】
実施例４〜７及び比較例３〜５で得られたセラミックシート付き離型フィルムの評価結果を表２に示す。
【０１６０】
【表２】

【０１６１】
実施例４、５、６、７は、セラミックシート表面のダイナミック硬度（Ａ）と離型層表面のダイナミック硬度（Ｂ）との関係が｜Ａ−Ｂ｜≦２０であり、ラブオフ値も５以下であり、セラミックシートの剥離不良は見られず、セラミックシートの剥離帯電は、１ｋＶ以下であり、セラミックシートと離型フィルムは、再付着することなく、簡単に剥がれ、セラミックシートの剥離面も平滑であった。
【０１６２】
それに対し、比較例３は、｜Ａ−Ｂ｜≦２０であり、ラブオフ値も５以下であり、セラミックシートの剥離不良は見られなかったが、セラミックシートの剥離帯電は、５ｋＶより大きく、セラミックシートと離型フィルムの再付着が発生した。またセラミックシートの剥離面は、シリコーン離型面の突起が転写しており、セラミックシートの厚みが薄くなったときは、厚み精度に大きな影響を与えることが予想される。
【０１６３】
比較例４は、｜Ａ−Ｂ｜＞２０であり、セラミックシートと離型層の剥離力は大きく、ラブオフ値も１０より大きかったので、離型層とポリエステルフィルムとの密着性が弱く、セラミックコート前に、離型層がコート設備の一部でこすられ、脱落したため、剥離時にセラミックシートが完全に破れた。
【０１６４】
比較例５は、｜Ａ−Ｂ｜＞２０、セラミックシートとの剥離力は大きくなり、剥離時にセラミックシートが完全に破れた。
【０１６５】
【発明の効果】
本発明のセラミックシート付き離型フィルムによれば、剥離時の剥離力が小さく、セラミックシートの製造時の剥離工程において、剥離不良のない適度の力でセラミックシートから離型フィルムの剥離除去が可能であり、また、離型面の表面凹凸をコントロールすることにより、特に薄膜セラミックシートの製造時のセラミックコート工程において、ピンホール等の欠点のない均一なセラミックシートを得ることができる。
【０１６６】
よって、本発明のセラミックシート付き離型フィルムは、セラミックシート、特に薄膜セラミックシートの製造に好適である。
【０１６７】
特に、本発明の請求項２に係るセラミックシート付き離型フィルムは、さらにポリエステルフィルムと離型層との密着性が良く、セラミックシートの製造時の剥離工程において、離型層の削れによる剥離不良をなくすことができ、セラミックシートと離型フィルムとの剥離帯電が小さいことから、いったん剥がした後に再付着するトラブルを防止することができる。また、離型面の平滑性が極めて優れているので、厚み３μｍ以下の超薄膜セラミックシートを厚み精度良く加工することが可能であり、特に超薄膜セラミックシートの製造に好適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release film with a ceramic sheet based on a polyester film, and more particularly to a release film with a ceramic sheet that is excellent in peelability and suitable for producing a thin ceramic sheet.
Furthermore, the present invention relates to a release film with a ceramic sheet suitable for producing a thin ceramic sheet having excellent peelability and smoothness and small peel charge, particularly a thickness of 3 μm or less.
[0002]
[Prior art]
A release film in which a polyester film such as polyethylene terephthalate or polyethylene naphthalate is used as a base material and a release layer is provided on the base material is generally widely used as a mount for adhesive labels, adhesive tapes and the like.
[0003]
In recent years, with the rapid spread of mobile phones, the demand for multilayer ceramic capacitors has increased. The multilayer ceramic capacitor has a characteristic of temporarily storing electricity and is an electronic component that is indispensable for an electronic circuit in order to stabilize a current. About 250 multilayer ceramic capacitors are used in mobile phones.
[0004]
When manufacturing a ceramic sheet for multilayer ceramic capacitors, a silicone resin film is applied to at least one side of a biaxially stretched polyester film that is excellent in mechanical strength, dimensional stability, heat resistance, price, etc. as a carrier film for processes. The provided release film is generally used. As such a release film having a silicone-based resin film, there are JP-A-60-141553, JP-A-3-231812, JP-B-4-59207, JP-B-6-2393, and the like. Are known.
[0005]
In recent years, in order to reduce the size and increase the capacity of a multilayer ceramic capacitor, it has been demanded that the thickness of the ceramic sheet be made thinner and laminated in multiple layers. Ceramic sheets having a thickness of about 7 to 10 μm are currently used. Moreover, the thing of thickness about 3-5 micrometers has been developed, and also the thing of thickness about 1-2 micrometers is being examined.
[0006]
However, as the thickness of the ceramic sheet is reduced, a new problem has arisen in that peeling force increases when the ceramic sheet is peeled from the release layer of the release film, resulting in frequent peeling defects. For this reason, a release film having a smaller peeling force than that of a conventional release film has been required. General-purpose release films that have been used for conventional labels, etc. are insufficient in terms of releasability for the production of thin-layer ceramic sheets, even if they have a low peel strength in their applications. There is a need for a release film with low strength.
[0007]
However, even if a release film with a small peel strength from a ceramic sheet of a specific composition is designed, the components of the ceramic sheet (type of ceramic, average particle size, type of binder, content ratio thereof, etc.) and ceramic As the thickness of the sheet changes, the peel force between the ceramic sheet and the release layer of the release film changes, so each time the release film composition of the release film that is optimal for the ceramic sheet of that specific composition is designed There was a need.
[0008]
Furthermore, as the thickness of the ceramic sheet is reduced, not only the coarse protrusions on the surface of the release layer of the release film but also the surface unevenness of the release layer has an effect on the thickness of the ceramic sheet. When the thickness is reduced, a higher level of smoothness is required for the release film as a support for the ceramic sheet.
[0009]
This is because if the surface roughness of the polyester base film, which is the support for the release film, is large, the required amount of the release agent cannot be applied to the protrusions, resulting in the original release properties of the release agent. Can not be pulled out. Also, if there are high protrusions on the surface of the release film, the convex shape of the release layer surface of the release film by the protrusions is transferred to the ceramic sheet in a concave shape, and the transferred portion is transferred to the ceramic sheet. It becomes a shape defect.
[0010]
This defect becomes apparent as the thickness of the ceramic sheet is reduced, and in particular, as the thickness of the ceramic sheet has become extremely thin as in recent years. The concave transfer marks on the ceramic sheet due to the high protrusions on the surface of the mold film cause the thickness accuracy of the ceramic sheet to be poor.
[0011]
Furthermore, when the concave transfer mark becomes strong, it does not stop at a mere dent but tends to be a pinhole penetrating, and in a severe case, the ceramic sheet may be torn at the time of peeling from the release film that is the support of the ceramic sheet. is there. Further, when a ceramic sheet having pinholes is used as a multilayer ceramic capacitor, short circuit failure or insulation resistance failure occurs, which becomes a fatal defect.
[0012]
In addition, a release layer containing a curable silicone resin as a main component is very easily charged, and also has a large peeling charge when the ceramic sheet is peeled off. For this reason, once peeled ceramic sheet is reattached to the release film, productivity is reduced, and when floating dust adheres to the release film to form a ceramic sheet, there are problems such as pinholes There is also a need for a release film that is generated and has a smaller release charge than that of a conventional release film or has a fast charge decay.
[0013]
By the way, the release layer surface of the release film on which the ceramic sheet is laminated is provided with a release layer surface of the release film in order to completely eliminate the concave transfer from the release layer of the release film to the ceramic sheet. Is preferably flat. However, when a ceramic sheet is laminated on a flat release layer surface and the ceramic sheet is peeled from the release film, there arises a problem that peeling charge becomes extremely large.
[0014]
In order to make the release layer surface flat, the polyester base film of the support is substantially free of particles usually used, and the catalyst-derived precipitates and foreign matters are removed at a high level. is required. When the polyester base film has a laminate structure of at least two layers, it is necessary to laminate a polyester film layer substantially free of particles on the surface on which the release layer is formed.
[0015]
The phrase “substantially free of particles” means that the particle content is below the detection limit when the particle content is measured by X-ray fluorescence analysis.
[0016]
A film having such an ultra-smooth surface is significantly deteriorated in handling properties such as slipperiness, rollability and blocking resistance, wear resistance, and scratch resistance.
[0017]
In JP-A-11-320524, the center line roughness of the release layer surface of the release film is set to 30 nm or less, the projection height is in the range of 0.05 to 0.3 μm, and the number is 0.4 μm or more. Although a regulated release film for molding a thin film green sheet has been disclosed, even a release film having a release layer having a surface as described above is particularly provided with a ceramic sheet layer having a thickness of 3 μm or less. When peeling from the release film, a slight protrusion shape on the release layer surface is transferred to the release surface side of the ceramic sheet layer.
[0018]
As the thickness of the ceramic sheet is further reduced, the influence of the transfer protrusion traces as described above on the thickness accuracy of the ceramic sheet increases.
[0019]
[Problems to be solved by the invention]
An object of the present invention is to provide a release film that eliminates such conventional problems and has a small peeling force during peeling and no defects such as pinholes in the ceramic sheet, particularly in the production of thin ceramic sheets. There is.
[0020]
Furthermore, another object of the present invention is to produce a stable ceramic sheet with a small peeling force at the time of peeling, particularly in the production of a thin ceramic sheet of 3 μm or less, and good adhesion between the release layer and the base sheet. Another object of the present invention is to provide a release film having a release layer that has a small peeling charge when peeling the ceramic layer from the film.
[0021]
[Means for Solving the Problems]
In the first aspect of the present invention, a release film with a ceramic sheet having a small absolute value of the difference in dynamic hardness between the surface of the ceramic sheet layer and the release layer surface of the release film is preferable in the peeling step during the production of the ceramic sheet. It has been found that a release film having a specific surface unevenness is found to exhibit a peelability and a preferable uniform coatability in a coating process during the production of a ceramic sheet.
[0022]
  That is, the first invention of the present invention is polyester.Made of filmBase filmOne sideA release layer with curable silicone resin as the main constituentBecomeRelease filmWhen,On the surface of the release layer of the release filmThe thickness is 3 μm or lessA release film with a ceramic sheet formed by laminating ceramic sheet layers,
  The base film is a polyester film having a single-layer structure containing particles in the film, or a laminated structure of at least two layers formed by laminating a particle-containing layer on the surface opposite to the release layer forming surface. A polyester film having
  The absolute value of the difference between the dynamic hardness A of the ceramic sheet layer surface and the dynamic hardness B of the release layer surface satisfies the following formula (1), and ten points in the measurement of the three-dimensional surface roughness of the release layer surface The release film with a ceramic sheet is characterized in that the relationship between the average roughness SRz (μm) and the thickness C (μm) of the ceramic sheet satisfies the following formula (2).
        | A-B | ≦ 20 (gf / μm²(1)
        SRz ≦ C / 2 (2)
[0023]
With the above configuration, the peeling force at the time of peeling is small, and in the peeling process at the time of manufacturing the ceramic sheet, the release film can be peeled and removed from the ceramic sheet with an appropriate force with no peeling failure. By controlling the surface irregularities, a uniform ceramic sheet free from defects such as pinholes can be obtained, particularly in the ceramic coating process during the production of the thin film ceramic sheet.
[0026]
  The second2According to the present invention, it has been found that by providing an antistatic layer with fast charge decay on the opposite surface of the release layer, the peeling charge between the release film and the ceramic is reduced, and the particles on the release surface of the release film are further reduced. The present inventors have found that a uniform ceramic sheet having a good thickness accuracy can be obtained by reducing the number of protrusions due to.
[0027]
  I.e.2The invention ofIn the release film with a ceramic sheet according to the first aspect of the invention, a release layer comprising a curable silicone resin as a main component on one side of a base film made of a polyester film and an antistatic layer on the other side A release film with a ceramic sheet formed by laminating a film and a ceramic sheet layer having a thickness of 3 μm or less on the surface of the release layer of the release film,
  The base film isA polyester film having a laminated structure of at least two layers, in which a polyester film layer substantially free of particles and a particle-containing layer are laminated on the surface opposite to the release layer forming surface;The antistatic layer has a ten-point average roughness SRz (μm), an average gradient SΔa, an average spatial wavelength Sλa (μm) and an area of 0.12 mm in three-dimensional surface roughness measurement.²The number of protrusions PC satisfies the following formulas (3) and (4).
          0.05 ≦ SRz ≦ 0.5 (3)
          SΔa × PC / Sλa ≧ 0.2 (4)
[0028]
With the above configuration, since the peeling charge between the ceramic sheet layer and the release layer of the release film is small, it is possible to prevent troubles that are reattached after being peeled off once. Furthermore, since the smoothness of the release surface is extremely excellent, it is possible to process an ultra-thin ceramic sheet having a thickness of 3 μm or less with high thickness accuracy, and is therefore suitable for producing a ceramic sheet, particularly an ultra-thin ceramic sheet. .
[0029]
  The second3The invention of the2Release film with ceramic sheet of the inventionInThe particle-containing layer is a coating layer mainly containing a polymer resin and particles.
[0030]
  The second4The invention of the2In the release film with a ceramic sheet of the invention, the particle-containing layer is a polyester film layer containing particles.is thereIt is characterized by that.
[0031]
  The second5The invention of the1,2nd, 3rd or 4thofIn the release film with a ceramic sheet of the invention, the particlesofIt is at least one selected from calcium carbonate particles having an average particle size of 5 μm or less, silica particles, crosslinked acrylic particles, crosslinked polystyrene particles, and benzoguanamine-based particles.
[0032]
With the above configuration, it is possible to obtain a release film that suppresses coarse protrusions and has excellent surface smoothness.
[0033]
  The second6The invention of the1,In the release film with a ceramic sheet of the second, third, fourth or fifth invention, the particlesofThe particle size distribution ratio satisfies the following formula (5), and the product of the average particle size and the particle content satisfies the following formula (6).
        0.2 ≦ D₅₀/ D_Five≦ 0.6 (5)
        150 ≦ D₅₀× E ≦ 10000 (6)
  Where D₅₀Is the particle size (μm) when the cumulative weight is 50%, D_FiveIndicates the particle diameter (μm) when the cumulative weight is 5%, and E indicates the particle content (ppm).
[0034]
  The second7The invention of the1,2nd, 3rd, 4th, 5th or 6thofIn the release film with a ceramic sheet of the present invention, the peel force measured after the release layer surface was rubbed 10 times with a friction material between the release layer and the adhesive layer of the ceramic sheet adhered to the release layer surface. The ratio (love-off value (P10 / P0)) between (P10) and the peeling force (P0) measured before friction is 10 or less.
[0035]
With the above configuration, since the release layer does not fall off from the polyester film during the ceramic processing step, the ceramic is uniformly coated, and the release film can be easily peeled off from the ceramic sheet. Can be reduced. On the other hand, if the rub-off value is too high, before the ceramic sheet layer is provided, a part of the silicone resin constituting the release layer falls off from the polyester base film, and the ceramic enters the removed part. As a result, there is a problem in that the ceramic sheet is broken at the time of peeling.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the release film with a ceramic sheet of the present invention will be described.
[0037]
The polyester constituting the polyester film used as the substrate of the present invention is not particularly limited, and a polyester resin that is generally used as a substrate for a release film can be used. Among these, a crystalline linear saturated polyester resin composed of an aromatic dicarboxylic acid component and a diol component is preferable, and examples thereof include polyethylene terephthalate, polyethylene-2-6 naphthalate, and polymethylene terephthalate.
[0038]
The polyester film used in the present invention is preferably a biaxially stretched polyester film, particularly from the viewpoint of mechanical strength, heat resistance, chemical resistance and the like.
[0039]
The manufacturing method of the polyester film in this invention is not specifically limited, The method generally used conventionally can be used. For example, the polyester is melted with an extruder, extruded into a sheet form from a T-die, and cooled and closely solidified with a rotary cooling drum while applying static electricity to obtain an unstretched sheet. Next, the unstretched film can be produced by uniaxially or biaxially stretching, followed by heat setting treatment and, if necessary, relaxation treatment. A uniaxially stretched film can be obtained by uniaxially stretching an unstretched film in the longitudinal direction or the transverse direction. Further, the biaxially stretched film is obtained by a method of sequentially biaxially stretching a uniaxially stretched film in the longitudinal direction or the transverse direction in the transverse direction or the longitudinal direction, or a method of simultaneously biaxially stretching an unstretched film in the longitudinal direction and the transverse direction. be able to.
[0040]
In this invention, it is preferable that the extending | stretching temperature at the time of extending | stretching a polyester film shall be more than the secondary transition point (Tg) of polyester and less than crystallization temperature. In the case of a biaxially stretched film, it is preferable that the stretching ratio is 1.1 to 8 times, preferably 2 to 6 times, particularly preferably 3 to 5 times in each direction.
[0041]
The thickness of the polyester film used in the present invention may be set according to the purpose of use and is not particularly limited, but is preferably 2 to 300 μm, and particularly preferably 10 to 125 μm.
[0042]
The silicone resin constituting the silicone release layer in the release film of the present invention is not particularly limited, and a curable silicone resin such as an addition reaction system, a condensation reaction system, an ultraviolet ray or an electron beam curable silicone resin is used. be able to.
[0043]
Examples of the addition reaction type silicone include those obtained by reacting polydimethylsiloxane having a vinyl group introduced at its terminal with hydrodienesiloxane using a platinum catalyst to form a three-dimensional crosslinked structure.
[0044]
Examples of the condensation reaction type silicone resin include those obtained by reacting polydimethylsiloxane having —OH group at the terminal with hydrodienesiloxane using a platinum catalyst to form a three-dimensional crosslinked structure.
[0045]
Examples of UV-curable silicone resins include those that use the same radical reaction as ordinary silicone rubber crosslinks as the most basic types, those that introduce photopolymerization by introducing unsaturated groups, and thiol addition to vinyl siloxane. Examples include those that crosslink by reaction, and those that decompose an onium salt with ultraviolet rays to generate a strong acid, thereby cleaving an epoxy group to crosslink. Since the electron beam has stronger energy than ultraviolet rays, the electron beam curable silicone resin undergoes a crosslinking reaction by radicals without using an initiator as in the ultraviolet ray curable system.
[0046]
In the release film with a ceramic sheet of the present invention, the absolute value | A−B | of the difference between the dynamic hardness A of the ceramic sheet surface laminated on the surface of the release layer and the dynamic hardness B of the release layer surface is 20 gf / μm²It is necessary to be the following, 15 gf / μm²The following is preferred. Particularly preferably 10 gf / μm²It is as follows.
[0047]
Absolute value | A−B | of the difference in dynamic hardness is 20 gf / μm²When the ceramic sheet layer is peeled from the release film, the releasability is reduced when the ceramic sheet is produced.In particular, in the case of a thin-layer ceramic sheet, the ceramic sheet is frequently broken or peeled off at the time of peeling. Problems such as a decrease in yield occur.
[0048]
By making the absolute value | A-B | of the difference of the dynamic hardness within the above range, the peeling force when peeling the ceramic sheet layer from the release film to produce the ceramic sheet is small, and the peeling is easy. Therefore, breakage of the ceramic sheet can be reduced.
[0049]
When the ceramic sheet layer is peeled from the release film to produce a ceramic sheet, the release form changes depending on the hardness of the ceramic sheet, and therefore it is necessary to change the hardness of the release layer surface of the release film.
[0050]
That is, when the ceramic sheet is hard or the thickness of the ceramic sheet is thin, since the influence of the viscosity of the ceramic sheet layer is hardly observed when the ceramic sheet layer is peeled off, the release layer of the release film It is preferable to harden the curable silicone resin which is a constituent component.
[0051]
The peeling behavior at the interface between the ceramic sheet and the release film is different from the peeling behavior at the interface between the normal adhesive sheet and the release film. That is, in the case of peeling at the interface between the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the release layer of the release film, the cohesive energy of the interface becomes dominant. On the other hand, in the case of peeling at the interface between the hard ceramic sheet and the release film, when the release layer is hard, the deformation of the release layer during peeling is small, and as a result, the peeling force is reduced. In addition, when the release layer is soft, deformation of the release layer during peeling is large, and as a result, the peeling force increases.
[0052]
Therefore, it is considered that the peeling behavior between the hard ceramic sheet and the hard release film is dominated by the interfacial shear force, not the interfacial peeling force as in the peeling between the adhesive sheet and the release film.
[0053]
The absolute value | A−B | of the dynamic hardness difference is 20 gf / μm.²In order to achieve the following, it is necessary to design the hardness of the release layer of the release film according to the hardness of the ceramic sheet layer.
[0054]
For example, when the ceramic sheet is composed of ceramic particles (barium titanate, alumina, aluminum nitride, etc.) and a binder (polyvinyl butyral, polyvinyl alcohol, etc.), the binder content ratio (weight ratio) to the ceramic particles is large. Or when the thickness of a ceramic sheet layer is thick, the hardness of the ceramic sheet at the time of laminating | stacking a ceramic sheet layer on a release film becomes small. Further, the dispersibility of the ceramic particles in the ceramic slurry also affects the hardness of the ceramic sheet. If the dispersibility of the ceramic particles at the time of mixing the ceramic slurry is insufficient, the hardness of the ceramic sheet becomes small.
[0055]
When peeling a ceramic sheet having a low hardness as described above, it is necessary to reduce the hardness of the release layer mainly composed of a curable silicone resin. For example, 1) inclusion of hydrophobic groups in the silicone resin This can be achieved by increasing the amount as much as possible, 2) reducing the content of crosslinking groups introduced into the silicone resin, or 3) using a silicone resin having a linear molecular structure. It is also effective to increase the thickness of the release layer.
[0056]
Moreover, when the content ratio (weight ratio) of the binder with respect to the ceramic particles is small, or when the thickness of the ceramic sheet layer is thin, the hardness of the ceramic sheet when the ceramic sheet layer is laminated on the release film increases.
[0057]
When peeling a ceramic sheet having a high hardness as described above, it is necessary to increase the hardness of the release layer mainly composed of a curable silicone resin. For example, inclusion of a hydrophobic group to be introduced into the silicone resin Although adjustment of the amount is necessary, it can be achieved by increasing the crosslinking density of the silicone resin by a method such as increasing the content of the crosslinking group introduced into the silicone resin.
[0058]
Also, if the thickness of the release layer containing curable silicone resin as the main component is uniform in the plane, the smaller the thickness, the greater the crosslink density even at a certain curing energy. Thus, the hardness of the release layer can be increased. Further, the hardness may be increased by increasing the mechanical strength of the base polyester film.
[0059]
Furthermore, the hardness can be controlled by the curing conditions of the release layer. For example, when an active energy ray curable silicone resin such as an ultraviolet curable type or an electron beam curable type is used as a constituent component of the release layer, the higher the temperature and irradiation amount when irradiating the active energy ray, the higher the silicone resin. The crosslink density increases, and the hardness of the release layer can be increased.
[0060]
Moreover, it is in the tendency for the adhesion durability of a mold release layer and a polyester base film to deteriorate, so that it is a mold release film with a small peeling force with a ceramic sheet layer. When the adhesion durability between the release layer and the substrate film is poor, the mold is released on the ceramic sheet manufacturing process, especially on the line where shearing force such as a driving roll is applied before the ceramic slurry is applied to the release film. The release layer of the film tends to fall off easily. In addition, when a slot die coater or a blade coater is used in the step of applying the ceramic slurry to the release film, the lip tip of the coater comes into contact with the release layer surface of the release film, thereby releasing the release film. The mold layer is easy to fall off. As a result, the peelability and smoothness of the ceramic sheet become insufficient, and the problem that the ceramic sheet is broken when the ceramic sheet is peeled easily occurs. Therefore, it is preferable that the release film has excellent adhesion durability between the release layer and the substrate film.
[0061]
Specifically, the release layer surface of the release film of the present invention preferably has a rub-off value (a measure of adhesion durability) of 10 or less, particularly preferably 5 or less. When the rub-off value exceeds 10, in the ceramic sheet manufacturing process, the release layer is likely to drop before the ceramic slurry is applied to the release layer of the release film. Therefore, if ceramic slurry is applied to the location where the release layer has fallen off, the thickness of the ceramic sheet layer will become non-uniform, and the ceramic sheet layer will likely fail to peel off at the location where the release layer has fallen off, reducing the yield. Problems occur.
[0062]
Here, the rub-off value is a parameter related to the durability of adhesion between the release layer and the polyester film of the support, and the lower the rub-off value, the better the durability of adhesion. Specifically, the peeling force between the release layer and the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is provided on the release layer surface, and the release surface of the release film is 2 N / cm.²Measured before and after 10 reciprocating frictions with a friction material under a load, and expressed as the ratio (P10 / P0) of the peel force after friction (P10) and the peel force before friction (P0) is there. A Gakushin friction Kenro tester was used as the friction tester, and a white polypropylene film was used as the friction material. The peeling force is a value measured when T-type peeling is performed at a rate of 300 mm / min using Tensilon after sticking an adhesive tape on the surface of the release layer and making a close contact with a 5 kgf pressure rubber roller.
[0063]
When the rub-off value of the release layer surface is 10 or less, that is, when the adhesion durability between the release layer and the polyester film is good, the release layer does not fall off from the polyester film. Therefore, the ceramic slurry is uniformly applied, the ceramic sheet layer can be easily peeled from the release film, and the breakage of the ceramic sheet can be reduced.
[0064]
In order to obtain a rub-off value within the above range, for example, it is necessary to complete the curing reaction or crosslinking reaction of the curable silicone resin in as short a time as possible. What is necessary is just to enlarge the energy required for hardening of a silicone resin, the addition amount of the catalyst at the time of addition reaction, etc. so that a bad effect may not arise.
[0065]
In the case of an active energy ray-curable silicone resin, it is preferable from the viewpoint of adhesion durability to increase the crosslinking density. In particular, since the ultraviolet cation curable silicone resin uses an epoxy group as a cross-linking group, the durability of adhesion to a polyester film improves as the cross-linking reaction is accelerated.
[0066]
Moreover, in order to further improve the adhesion durability between the release layer and the polyester film of the support, prior to applying the release layer coating solution to the film, the polyester film surface is subjected to anchor coating or corona treatment, A pretreatment such as a flame treatment may be performed.
[0067]
Examples of the antistatic agent constituting the antistatic layer in the release film of the present invention include an anionic antistatic agent having a functional group such as an alkyl sulfate type and an alkyl phosphate type, a quaternary ammonium salt type, and a quaternary ammonium. Examples thereof include cationic antistatic agents such as resin type and imidazoline type, nonionic antistatic agents such as sorbitan type and ether type, and amphoteric antistatic agents such as betaine type. Further, a conductive polymer such as polyaniline may be used.
[0068]
By providing the antistatic layer on the surface opposite to the release layer, the release charge can be lowered when the ceramic sheet is released from the release layer. By lowering the peeling electrification between the ceramic sheet layer and the release layer, the problem that the peeled ceramic sheet is reattached to the release film can be prevented.
[0069]
The surfactant type antistatic agent is preferably a polymer type, and more preferably a number average molecular weight of 5000 or more, particularly 50000 or more. When the number average molecular weight is less than 5,000, the adhesive force of the release layer to the base film tends to be inferior, and when this release film is wound up in a roll or superposed on a sheet, The component in the prevention layer adheres to the release layer surface of the base film, and when the secondary processing is performed on the release layer surface, peeling failure occurs, or the secondary processing causes the antistatic coating layer itself to peel off. The inside of the processing process may be contaminated, which is not preferable. Further, the antistatic performance is unstable due to peeling of the antistatic layer, which is not preferable. In order to prevent these phenomena, a wax, a silicone component, or the like may be mixed in the antistatic layer.
[0070]
In order to reduce the peeling charge between the ceramic and the silicone layer as described above, an antistatic layer can be provided on the opposite side of the silicone layer. More preferably, an antistatic layer having an excellent charge attenuation effect is preferable. Although not particularly limited, among the antistatic agents, cationic antistatic agents and conductive polymers such as polyaniline are preferable. More preferably, an antistatic agent having quaternized nitrogen is preferable. Surprisingly, the use of antistatic having excellent charge attenuation properties has the effect of reducing the peeling charge on the side of the ceramic sheet to be peeled, simply by having the antistatic layer on the opposite side of the peeled surface.
[0071]
In the present invention, the thickness of the release layer may be set according to the purpose of use, and is not particularly limited, but preferably the coating amount of the release layer after curing is 0.02 to 0.2 g / m.²The range is good. If the thickness of the release layer is smaller than the above range, the peeling performance tends to be lowered. Moreover, if larger than the said range, the hardening time required for the adhesiveness of polyester will become long, and it will become inconvenience on production. Furthermore, it becomes difficult to control the surface irregularities on the surface of the release layer, which is not preferable.
[0072]
Further, the thickness of the antistatic layer may be set according to the purpose of use and is not particularly limited, but preferably the coating amount of the antistatic layer is 0.005 to 0.5 g / m.²The range is good. If the thickness of the antistatic layer is smaller than the above range, the antistatic performance tends to deteriorate. On the other hand, if it is larger than the above range, tackiness appears in the antistatic layer, and the antistatic component is liable to be transferred or dropped off.
[0073]
The method for forming the release layer of the present invention is not particularly limited. For example, a coating liquid in which a curable silicone resin is dispersed is spread on the surface of the polyester film of the substrate by coating or the like, and the solvent is dried. After the removal, the method of reacting and curing the resin with heat is used.
[0074]
The method for forming the antistatic layer of the present invention is not particularly limited. For example, a coating solution in which an antistatic agent is dissolved is applied to the surface of the polyester film opposite to the release layer by coating or the like. A method of developing and removing the solvent by drying is used.
[0075]
Further, either the release layer or the antistatic layer may be formed first. The method for forming the release layer of the present invention is not particularly limited. For example, a coating liquid in which a curable silicone resin is dispersed is applied to the surface of the polyester film of the base material, the solvent is dried, and then the resin is heated by heat. A method of reacting and curing is used.
[0076]
As the coating method of the coating solution, any known coating method can be applied. For example, conventionally known methods such as a roll coating method such as a gravure coating method and a reverse coating method, a bar coating method such as a Mayer bar, a spray coating method, and an air knife coating method can be used.
[0077]
In the present invention, when the release layer is formed, a coating liquid containing a curable silicone resin that does not use a solvent is applied to a polyester base film, dried, and then subjected to an active energy curing reaction or a thermosetting reaction, A coating solution in which a silicone curable resin is dissolved or dispersed in a solvent is applied to a polyester base film, and after the solvent is removed by drying, an active energy curing reaction or a thermosetting reaction is performed.
[0078]
The active energy reaction curing condition or thermal curing condition of the resin and the drying condition of the solvent may be selected as appropriate depending on the type of resin used, the thickness of the release layer, the size of the release film, and the like.
[0079]
For example, when irradiating an ultraviolet curable silicone resin layer with ultraviolet rays, 100 mJ / cm²As described above, the solvent is preferably dried at 100 ° C. or lower. The amount of UV irradiation is 100mJ / cm²If it is smaller, the reaction curing of the silicone resin tends to be incomplete, resulting in heavy release (heavy release force), increased rub-off value (adhesion with the film becomes worse), and the back side of the silicone release layer There is a possibility of causing transfer (setback).
[0080]
Moreover, when the drying conditions of the solvent are higher than 100 ° C., the flatness of the film may be deteriorated.
[0081]
Further, the surface unevenness of the release surface side surface of the release film thus produced, that is, the ten-point average roughness SRz (μm) in the three-dimensional surface roughness measurement of the release layer surface and the thickness of the ceramic sheet. C (μm) needs to be in the range of the following formula (2).
SRz ≦ C / 2 (2)
[0082]
SRz on the surface of the release layer is preferably 1/5 or less, particularly preferably 1/10 or less, with respect to the thickness C of the ceramic sheet from the viewpoint of reducing pinholes in the ceramic sheet.
[0083]
The ten-point average roughness SRz of the release layer surface was measured with a three-dimensional surface roughness meter manufactured by Kosaka Laboratory.
[0084]
If the ten-point average roughness SRz (μm) of the release layer exceeds 1/2 of the thickness C (μm) of the ceramic sheet, defects such as pinholes are likely to occur in the ceramic sheet.
[0085]
The method for controlling the SRz of the release layer of the release film is arbitrary and not particularly limited. For example, a specific amount of specific particles are contained in the polyester base film or the anchor coat layer (coating layer), Depending on the thickness of the ceramic sheet layer, there may be mentioned a method of controlling the release layer of the release film to have SRz.
[0086]
As an example, a method for incorporating a specific amount of specific particles in a polyester base film will be described below.
[0087]
As the particles, inorganic particles and / or heat-resistant organic particles that are inert when added to the polyester polymerization reaction system are used. However, particles that greatly impair the transparency of the film for inspection of defects such as pinholes in ceramic sheets are not preferred.
[0088]
Examples of the inorganic particles include calcium carbonate particles, silica particles, alumina-silica composite oxide particles, and hydroxyapatite particles. Examples of the heat resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. These particles are preferably used alone or in combination. In particular, silica having a refractive index close to that of polyester is preferable in terms of transparency of the film.
[0089]
The average particle diameter of the particles is not limited as long as the above formula (2) is satisfied, but is preferably 5 μm or less, more preferably 2 μm or less, particularly preferably 2 μm or less, from the viewpoint of suppression of coarse protrusions and surface smoothness. Is 0.7 μm or less. When the thickness exceeds 5 μm, coarse protrusions are generated, and the surface smoothness is deteriorated. The lower limit value of the average particle diameter is preferably 0.01 μm.
[0090]
The particle size distribution ratio of particles (particle size distribution measuring device: SA-CP3, manufactured by Shimadzu Corporation) and the product of the average particle size and the content are expressed by the following formula (5) from the viewpoint of suppressing the number of coarse protrusions and sliding properties. And it is preferable that the range satisfies (6).
0.2 ≦ D₅₀/ D_Five≦ 0.6 (5)
150 ≦ D₅₀× E ≦ 10000 (6)
[0091]
In the formula, D₅₀Is the particle size (μm) when the cumulative weight is 50%, D_FiveIndicates the particle diameter (μm) when the cumulative weight is 5%, and E indicates the particle content (ppm).
In this case, the particle size distribution ratio (D₅₀/ D_FiveThe larger the value of), the narrower the particle size distribution width, and the particle size distribution ratio (D₅₀/ D_Five) Is preferably in the range of 0.2 to 0.6.
[0092]
Particle size distribution ratio (D₅₀/ D_Five) Is practically very difficult to produce a particle size distribution exceeding 0.6 within the practical range. Conversely, if the particle size distribution is less than 0.2, the average particle size (D₅₀) Causes problems such as insufficient slipperiness or an increase in the number of coarse protrusions.
[0093]
Further, the content E (ppm) of the particles is the average particle diameter D₅₀(Μm) must be determined in combination with E and D as shown in the equation (4).₅₀It is preferable to select the range of 150 to 10,000. If it is less than 150, the slipperiness becomes insufficient. Conversely, if it exceeds 10,000, the number of coarse protrusions increases, such being undesirable.
[0094]
For example, in the case of a thin film having a ceramic sheet layer thickness of 3 μm or less, no particles are contained in the polyester base film. When particles are contained in the polyester base film, projections are formed on the surface of the release layer, which is not preferable. If particles are not included, problems such as poor slipping between films occur. Therefore, fine surface protrusions are required on the opposite surface of the release layer surface. Fine surface protrusions must satisfy the following formulas (3) and (4).
0.05 ≦ SRz ≦ 0.5 (3)
SΔa × PC / Sλa ≧ 0.2 (4)
[0095]
Here, SRz, SΔa, and Sλa indicate ten-point average roughness (μm), average gradient, and average wavelength (μm), respectively, in the three-dimensional surface roughness measurement, and PC has an area of 0.12 mm.²The number of protrusions is shown.
[0096]
When SRz exceeds 0.5 μm, a ceramic layer is formed on the release layer, and when wound into a film roll, protrusions on the opposite surface of the release layer are transferred to the ceramic sheet, which is not preferable. If it is less than 0.05 μm, it is too smooth and practically difficult to handle. The upper limit of SRz on the surface of the antistatic layer is preferably 0.4 μm or less, more preferably 0.3 μm or less, and particularly preferably 0.25 μm or less from the viewpoint of preventing transfer to the opposite ceramic sheet surface. . In addition, the lower limit value of SRz on the surface of the antistatic layer is preferably 0.07 μm or more, particularly preferably 0.10 μm or more, from the viewpoint of handling properties.
[0097]
Next, the technical meaning of the parameter “SΔa × PC / Sλa” will be described.
[0098]
The three-dimensional center plane average roughness SRa (μm) is defined by 2π × Sλa / SΔa. Therefore, the relationship SΔa × PC / Sλa∝PC / SRa can be derived. That is, in order to increase PC / SRa, it is effective to increase PC (number of protrusions) or decrease SRa (average roughness). As a specific surface form, it is preferable that a large number of small protrusions exist rather than a large protrusion sparsely exist.
[0099]
If SΔa × PC / Sλa is less than 0.2, it may cause runnability and other film defects during the processing step. The lower limit value of SΔa × PC / Sλa is preferably 0.4 or more, and particularly preferably 0.6 or more. On the other hand, the upper limit value of SΔa × PC / Sλa is not particularly limited, but is preferably 2.0 or less from the viewpoint of transparency. If the transparency is deteriorated, it becomes difficult to detect the defect because light becomes difficult to transmit during the defect inspection such as the pinhole of the ceramic sheet.
[0100]
Fine surface protrusions can be formed by coating one side of the film with a coating solution to which inert particles are added, or by coextrusion of a thin film layer containing inert particles. The shape of the inert particles is preferably a spherical shape rather than an indefinite shape, for example, because no transfer marks of protrusions remain.
[0101]
In the present invention, the method for adding particles to the polyester film can be added at any stage in the production process of the polyester film, but it is preferably added before the initial condensation is completed.
[0102]
The method for adding particles to the polyester film production process may be added in either a slurry or powder state, but it is dispersed in the form of a slurry from the viewpoint of preventing particle scattering and improving the uniformity of supply accuracy. It is preferable to add it, and it is particularly preferable to add it as a slurry of ethylene glycol.
[0103]
The release film with a ceramic sheet can be produced, for example, by the following method.
[0104]
  First, ceramic powder such as barium titanate, alumina, aluminum nitride is mixed and dispersed in an aqueous or organic solvent, and then a polymer binder such as polymethyl methacrylate, polyvinyl acetal, polyvinyl butyral, polyvinyl alcohol, plasticizer, dispersant , Mixed and dispersed by a high-speed mixer or ball mill, then filtered (for example, a filter having a pore diameter of 3 μm), and the resulting ceramic slurry was dried on the release layer surface of the release film with a thickness of 1 to 13It can be manufactured by applying and drying to a thickness of μm. Examples of the coating method include a doctor blade method, a micro gravure roll method, a reverse roll method, a slot die coater, and a blade coater.
[0105]
Example
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The properties and physical properties used in the present invention were measured by the following methods.
[0106]
(1) Intrinsic viscosity of polyester
The polyester was dissolved in a mixed solvent of 60% by weight of phenol and 40% by weight of 1,1,2,2-tetrachloroethane, and the undissolved solid content was removed with a glass filter.
[0107]
(2) Dynamic hardness
Using a dynamic ultra-small hardness meter (Shimadzu Corporation, DUH-201-202), press the triangular crest with a load of 2 gf against the sample (ceramic sheet surface or release layer surface), and the dynamic hardness after holding for 2 seconds. It calculated | required from the following formula. In addition, the measurement was performed 10 times and those average values were used. In addition, the measurement of the dynamic hardness on the release layer surface of the release film may be performed on the release film before the ceramic sheet layer is provided, or the release is performed after the ceramic sheet layer is released after the ceramic sheet layer is provided. It may be performed on the film.
[0108]
Dynamic hardness (gf / μm²) = Α × P / D²
Here, P is the weight (gf), D is the penetration amount (μm) of the indenter into the sample, and α is a constant (115 ° triangular cone) according to the indenter shape, which is 37.838.
[0109]
(3) Love-off value
A white polypropylene film (made by Toyobo Co., Ltd., Pearl SS, thickness 35 μm), which is a friction material, and the release layer surface of the release film are superposed on each other, and a Gakushin frictional Kenro tester (manufactured by Yamaguchi Kagaku Sangyo) 2N / cm²10 reciprocating rubs were performed under the load of. Note that the friction material was replaced with a new one every time the friction was completed for one round trip.
[0110]
Next, an adhesive tape (Nitto Denko, Nitto 31B) was attached to the release layer surface of the release film before and after the friction, and was brought into close contact with a 5 kgf pressure rubber roller. After 2 hours, T-type peeling using Tensilon was performed at a speed of 300 mm / min, the peeling force between the release layer of the release film and the adhesive layer of the adhesive tape was measured, and the peeling force after friction (P10) It was shown by the ratio (P10 / P0) to the peeling force (P0) before friction, and was taken as the rub-off value. The obtained rub-off values were classified according to the following three criteria. In addition, if it is more than (triangle | delta), it can be used practically.
○: ≦ 5.0
Δ: Over 5.0 and 10.0 or less
×:> 10.0
[0111]
When measuring the rub-off value of the release layer of the release film from the release film with the ceramic sheet, the rub-off value for the release film obtained by peeling the ceramic sheet layer from the release film with the ceramic sheet with an adhesive tape. Measure.
[0112]
(4) Peelability of ceramic sheet
A release film with a ceramic sheet is cut to a width of 5 cm, a polyester adhesive tape (Nitto 31B, manufactured by Nitto Denko Corporation) is pasted on the ceramic sheet layer surface, and the ceramic sheet layer is peeled off (peeling speed: 500 mm / min, T-type peeling). Was peeled from the release film and evaluated according to the following criteria. In addition, the test was performed 5 times, and if it was (circle), it was set as the pass.
○: When the entire surface of the ceramic sheet after peeling was visually observed, the ceramic sheet was not damaged such as pinholes or tears in five tests.
Δ: When the entire surface of the ceramic sheet after peeling was visually observed, a part of the ceramic sheet was damaged even once in five tests.
X: When the ceramic sheet was torn and damaged even once in five tests when the entire surface of the ceramic sheet after peeling was visually observed
[0113]
(5) Voltage at the time of ceramic sheet peeling
The release film with a ceramic sheet obtained by laminating the ceramic sheet layer on the release layer surface of the release film obtained in the above (4) is cut to a width of 5 cm. Next, the ceramic sheet layer was peeled from the release layer surface of the release film by a peel method (peeling speed 500 mm / min, T-type peeling). The voltage on the peeled ceramic sheet side was measured at 20 ° C. in an atmosphere of 50% RH using a digital electrostatic potential measuring device (KSD-0103, manufactured by Kasuga Denki Co., Ltd.). Evaluation was made according to three criteria. In addition, (circle) was set as the pass.
○: ≤ 1 kV
Δ: Over 1 kV and below 5 kV
×:> 5kV
[0114]
(6) Three-dimensional surface roughness parameter and number of surface protrusions
Using a stylus type three-dimensional surface roughness meter (SE-3AK, manufactured by Kosaka Laboratories), the surface of the sample was measured under the conditions of a needle radius of 2 μm, a load of 30 mg, and a needle speed of 0.1 mm / second. Measured over a length of 1 mm with a cut-off value of 0.25 mm in the longitudinal direction, divided into 500 points at a pitch of 2 μm, and the height of each point is determined by a three-dimensional roughness analyzer (manufactured by Kosaka Laboratory, SPA-11) Was taken in. The same operation was performed 150 times continuously at 2 μm intervals in the width direction of the film, that is, over 0.3 mm in the width direction of the film, and the data was taken into the analyzer. Next, SRz, SΔa, and Sλa were obtained using the analyzer.
[0115]
Here, SRz is a three-dimensional ten-point average roughness, and a higher value means that a higher protrusion exists.
[0116]
SΔa is a three-dimensional average gradient of the entire film surface and is defined as follows. The cross-sectional area and the number of protrusions of the film at each level horizontal to the center plane are obtained, and the average area of the protrusion cross-section at each level is calculated and converted to an average circle radius. The ratio (gradient) of the change of the average circle radius to the change of the height is obtained by the cutting plane of each level, and each value is averaged to be SΔa.
Here, SΔa specifically refers to the height of a predetermined number of measurement points that are spaced apart at a fixed interval by the stylus type three-dimensional surface roughness meter, and these measured values are measured with the three-dimensional surface roughness. This is the value obtained by importing into the analyzer. More specifically, the obtained surface roughness curve is approximated by a sine curve, and three-dimensional data is obtained by combining the data, and the slope of the entire surface is determined from the number and height of the projections with the center plane as the reference plane. Calculated.
An orthogonal coordinate axis system consisting of an X axis and a Y axis is placed on the center plane, the axis orthogonal to the center plane is taken as the Z axis, the X axis length Lx, the Y axis length Ly, and the area Lx × Ly on the center plane = S_MFrom this extracted portion, SΔa is expressed by the following equation.
[0117]
[Expression 1]

[0118]
Here, Z = f (x, y) means a function representing the height Z of the film surface at the position (x, y) on the orthogonal coordinate axis, and Lx = 500 and Ly = 150.
[0119]
Sλa is a three-dimensional spatial average wavelength and means the amplitude of the surface roughness curve. That is, if the center surface average surface roughness is the same, Sλa becomes smaller as the protrusion becomes steeper.
[0120]
The number of protrusions PC was determined by taking a film of aluminum deposited using a differential interference microscope (Nikon) at a final magnification of 160 times, tracing the protrusions on a transparent OHP sheet, and an image analyzer (Luzex IID) manufactured by Nireco. And the film 0.12mm²The area corresponding to is image-processed, and the number of protrusions within the area is calculated.
[0121]
(7) Smoothness of the peeled ceramic sheet surface
A release film with a ceramic sheet is cut to a width of 5 cm, a polyester adhesive tape (Nitto 31B, manufactured by Nitto Denko Corporation) is pasted on the ceramic sheet layer surface, and the ceramic sheet layer is peeled off (peeling speed: 500 mm / min, T-type peeling). Was peeled from the release film, and the peeled ceramic sheet surface was observed 200 times with a differential interference microscope (Nikon Corp.).
[0122]
(8) Ceramic sheet pinhole
The release film with a ceramic sheet was cut into a width of 100 mm and a length of 1 m. Place the release film with the ceramic sheet on the tracer trace table (manufactured by KOKUYO) so that the upper surface is the ceramic sheet surface, and count the number of spots where light leaks from the ceramic sheet surface by applying light from the lower surface, 1m²Converted to the number of pieces per round and rounded off the first decimal place.
○: 10 / m²Less than
Δ: 20-50 pieces / m²
×: 60 or more / m²
[0123]
(Example 1)
There is an esterification reaction product of the first esterification reactor using a continuous esterification reactor comprising a two-stage complete mixer equipped with a stirrer, a partial condenser, a raw material charging port and a product outlet. An ethylene glycol slurry containing 289 ppm per unit of terephthalic acid with antimony trioxide as an antimony atom was continuously supplied to the system to a molar ratio of ethylene glycol to terephthalic acid of 1.7.
[0124]
At the same time, the ethylene glycol slurry supply port of terephthalic acid is 100 ppm as Mg atoms per unit of polyester in the reaction product passing through the reaction vessel through the ethylene glycol solution of magnesium acetate tetrahydrate from another supply port. Thus, the reaction was carried out at normal pressure and an average residence time of 4.5 hours at a temperature of 255 ° C.
[0125]
This reaction product was continuously taken out of the system and supplied to the second esterification reactor. With respect to the polyester unit in the reaction product passing through the second esterification reactor, 0.5 parts by weight of ethylene glycol and trimethyl phosphate in an ethylene glycol solution of 64 ppm as P (phosphorus) atoms, and an average particle size D₅₀(SA-CP3, manufactured by Shimadzu Corporation) is 0.9 μm, D₅₀/ D_FiveIs continuously supplied from a separate supply port so that an aqueous solution of sodium tripolyphosphate of 100 g / L as Na atoms becomes 2500 ppm as calcium carbonate in the slurry. The reaction was carried out at a temperature of 260 ° C. for an average residence time of 5 hours.
[0126]
The esterification reaction product is continuously supplied to a two-stage continuous polycondensation reaction apparatus provided with a stirrer, a partial condenser, a raw material charging port, and a product take-out port to perform polycondensation, and an intrinsic viscosity of 0.62 dl / G of polyester was obtained.
[0127]
The polymer was melt extruded at 290 ° C., stretched 3.5 times in the machine direction at 90 ° C. and 3.5 times in the transverse direction at 130 ° C., and then heat-treated at 220 ° C. to form a biaxially stretched polyester film having a thickness of 38 μm. Was wound up into a roll.
[0128]
Next, an ultraviolet cationic curable silicone resin (Toshiba Silicone, UV9315) is dispersed in a solvent (normal hexane) so that the resin solids concentration is 2% by weight, and 1 part by weight with respect to 100 parts by weight of the silicone resin. Bis (alkylphenyl) iodonium hexafluoroantimonate was added as a curing catalyst to prepare a coating solution containing a silicone resin.
[0129]
The biaxially stretched polyester film roll having a thickness of 38 μm is unwound, the coating liquid containing the silicone resin is applied to one side of the film with a wire bar, dried at 100 ° C. × 30 seconds, and then irradiated with ultraviolet rays using an ultraviolet irradiation device. (300mJ / cm²) And release film (coating amount after drying of silicone release layer 0.10 g / m)²) And wound up into a roll.
[0130]
Further, ceramic particles (barium titanate (BaTiO 3 having an average primary particle size of 0.6 μm) in a solvent (toluene / ethanol = 50/50: weight ratio)._Three), Fuji Titanium Co., Ltd.) was mixed with 100 parts by weight, and dispersed in a ball mill for 24 hours together with zirconia beads having a particle size of 1.5 mm (filling amount: 200% by weight based on the slurry). Next, 10 parts by weight of a binder (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) and 2% by weight of a plasticizer (polyethylene glycol) are mixed with respect to the total amount of the ceramic powder and the binder, dispersed in a ball mill for 24 hours, and further filtered (pore size 3 μm). ) To obtain a paste-like ceramic slurry.
[0131]
The release film roll is unwound, the ceramic slurry is applied to the release layer surface of the release film by a doctor blade method, dried at 120 ° C. for 1 minute, and a ceramic sheet layer (ceramic particle / binder) having a thickness of 3 μm. = 100/10: weight ratio) to obtain a release film with a ceramic sheet.
[0132]
(Example 2)
A thermosetting silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KS830) is dispersed in a solvent (toluene) so that the resin solid content concentration is 3% by weight, and 1 part by weight of a platinum catalyst is added to 100 parts by weight of the silicone resin. Add a coating solution containing silicone resinCreatedid. This coating solution was applied to one side of the biaxially stretched polyester film of Example 1 with a wire bar, dried at 140 ° C. for 30 seconds, and the coating amount after drying was 0.05 g / m.²A release film having a release layer was produced and wound into a roll. Further, a release film with a ceramic sheet was obtained in the same manner as in Example 1.
[0133]
(Example 3)
In Example 1, instead of the calcium carbonate particles, the average particle diameter D₅₀A release film with a ceramic sheet was obtained in the same manner as in Example 1 except that 60 ppm of 2.47 μm silica particles were contained in the polyester.
[0134]
(Comparative Example 1)
In Example 2, the coating amount after drying of the release layer was 0.5 g / m.²A release film with a ceramic sheet was obtained in the same manner as in Example 2 except that.
[0135]
(Comparative Example 2)
In Example 3, a release film with a ceramic sheet was obtained in the same manner as in Example 3 except that the thickness of the ceramic sheet layer was 2 μm.
Table 1 shows the evaluation results of the release films with ceramic sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2.
[0136]
[Table 1]

[0137]
In Examples 1, 2, and 3, the relationship between the dynamic hardness (A) of the ceramic sheet surface and the dynamic hardness (B) of the release layer surface is | A−B | ≦ 20. The ten-point average roughness SRz of the release layer was not more than ½ of the thickness of the ceramic sheet, and no pinhole defect occurred.
[0138]
On the other hand, in Comparative Example 1, the difference in dynamic hardness | A−B | was greater than 20, and defective ceramic peeling was observed.
[0139]
In Comparative Example 2, | A−B | ≦ 20, but the SRz was larger than ½ of the thickness of the ceramic sheet, and a pinhole defect occurred in the ceramic sheet.
[0140]
(Example 4)
A biaxially stretched polyethylene terephthalate film was obtained by the following method. When the temperature of the esterification reactor was raised to 200 ° C., a slurry comprising 86.4 parts by weight of terephthalic acid and 64.4 parts by weight of ethylene glycol was charged, and 0% of antimony trioxide was added as a catalyst while stirring. 0.03 part by weight, 0.088 part by weight of magnesium acetate tetrahydrate and 0.16 part by weight of triethylamine were added. Next, the pressure is raised and the gauge pressure is 3.5 kg / cm.²The pressure esterification reaction was carried out at 240 ° C. Thereafter, the inside of the esterification reaction can was returned to normal pressure, and 0.040 parts by weight of trimethyl phosphate was added. Further, the temperature was raised to 260 ° C., and trimethyl phosphate was added.
[0141]
After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to a polycondensation reaction under reduced pressure at 280 ° C. After completion of the polycondensation reaction, filtration was performed with a nylon filter having a 95% cut diameter of 28 μm (manufactured by Nippon Seisen Co., Ltd.) to obtain polyethylene terephthalate having an intrinsic viscosity of 0.62 dl / g.
[0142]
This polyethylene terephthalate was dried under reduced pressure at 135 ° C. for 6 hours (1 Torr), then supplied to an extruder, melted and extruded into a sheet at about 280 ° C., and rapidly cooled and solidified on a metal roll maintained at a surface temperature of 20 ° C. An unstretched polyester film having a thickness of 532 μm was obtained. In this melt extrusion step, a stainless sintered filter medium having a filter medium particle size (initial filtration efficiency of 95%) of 15 μm was used as a filter agent for removing foreign substances from the molten resin.
[0143]
Next, this unstretched film was heated to 100 ° C. with a heated roll group and an IR heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a peripheral speed difference to obtain a uniaxially stretched polyester film. . Subsequently, 5 parts by weight of a polyester copolymer (manufactured by Toyobo Co., Ltd., MD1200), silicon dioxide (SiO 2 having an average primary particle size of 0.05 μm)₂) Is coated on one side of the uniaxially stretched film with 25000 ppm based on the weight of the polyester copolymer, 47.5 parts by weight of water, and 47.5 parts by weight of isopropyl alcohol, and dried with hot air at 70 ° C. Next, the end of the film is held with a clip and guided to a hot air zone heated to 130 ° C., dried, stretched 4.0 times in the width direction, and then heat treated at 220 ° C., and a coating layer is formed on one side having a thickness of 38 μm. A biaxially stretched polyester film having was obtained.
[0144]
0.2 parts by weight of a cationic polymer antistatic agent (trade name Chemistat 6300H: manufactured by Sanyo Chemical Industries), 0.1 part by weight of polyethylene wax (trade name Hitech E6000: manufactured by Toho Chemical Co., Ltd.), 50 parts by weight of methanol, 49.7 parts by weight of water was mixed to prepare a coating solution, and this was a wire bar on the coating layer of a biaxially stretched polyethylene terephthalate film (thickness 38 μm) having a coating layer on one side obtained by the above method, The coating amount after drying is 0.08 g / m²And then dried in a hot air dryer at 90 ° C. for 30 seconds.
[0145]
Next, an ultraviolet cation curable silicone resin (UV9315 manufactured by Toshiba Silicone Co., Ltd.) is dispersed in a solvent (normal hexane) so that the resin solid content concentration is 2% by weight, and 1 part by weight with respect to 100 parts by weight of the silicone resin. Bis (alkylphenyl) iodonium hexafluoroantimonate was added as a curing catalyst to prepare a coating solution containing a silicone resin. A coating solution containing the silicone resin is applied to the surface opposite to the antistatic layer of the antistatic polyester film having a thickness of 38 μm with a wire bar, dried at 100 ° C. × 30 seconds, and then irradiated with an ultraviolet irradiation device. UV irradiation (300 mJ / cm²And a release film having an antistatic layer (the coating amount after drying of the release layer: 0.10 g / m)²) Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0146]
(Example 5)
A thermosetting silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KS830) is applied to the surface opposite to the antistatic layer of the antistatic polyester film of Example 4 in a solvent (toluene) and the resin solid content concentration becomes 3% by weight. 1 parts by weight of platinum catalyst is added to 100 parts by weight of the silicone resin to prepare a coating solution containing a silicone resin, and applied to one side of the film with a wire bar, 140 ° C. × 30 seconds. And release the release antistatic film (silicone release layer after drying 0.05 g / m²) Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0147]
(Example 6)
UV irradiation amount is 500mJ / cm²A release film having an antistatic layer was obtained in the same manner as in Example 4 except that the above was obtained. Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0148]
(Example 7)
Calcium carbonate particles (manufactured by Maruo Calcium Co., Ltd.) having an average particle size of 0.6 μm measured with a light transmission type particle size distribution measuring device (manufactured by Shimadzu Corporation, SA-CP3) are charged into ethylene glycol, and further 95% cut diameter is 30 μm A viscose rayon filter was used to obtain an ethylene glycol slurry of calcium carbonate particles.
[0149]
Next, when the temperature of the esterification reactor was raised and reached 200 ° C., a slurry consisting of 86.4 parts by weight of terephthalic acid and 64.4 parts by weight of ethylene glycol was charged, and trioxide as a catalyst while stirring. 0.03 part by weight of antimony, 0.088 part by weight of magnesium acetate tetrahydrate, and 0.16 part by weight of triethylamine were added.
[0150]
Next, the pressure is raised and the gauge pressure is 3.5 kg / cm.²The pressure esterification reaction was carried out at 240 ° C. Thereafter, the inside of the esterification reaction can was returned to normal pressure, and 0.040 parts by weight of trimethyl phosphate was added. Further, the temperature was raised to 260 ° C., and 15 minutes after addition of trimethyl phosphate, the ethylene glycol slurry of the calcium carbonate particles was added to 1000 ppm with respect to the produced polyester. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to a polycondensation reaction under reduced pressure at 280 ° C.
[0151]
After completion of the polycondensation reaction, it was filtered through a NASRON filter (manufactured by Nippon Seisen Co., Ltd.) having a 95% cut diameter of 28 μm, and polyethylene terephthalate pellets containing calcium carbonate particles having an intrinsic viscosity of 0.62 dl / g ( B) was obtained.
[0152]
The polyethylene terephthalate pellets (B) containing the calcium carbonate particles and the polyethylene terephthalate pellets (A) not containing the same particles as in Example 4 were dried under reduced pressure (3 Torr) at 135 ° C. for 6 hours, and then the extruder 1, Each was supplied to the extruder 2 and melted at 285 ° C.
[0153]
The two polymers are each filtered with a filter medium made of a sintered stainless steel (nominal filtration accuracy: 95 μm particles cut to 95%), laminated in a two-layer confluence block having a rectangular laminated portion, and formed into a sheet form from the die. After extrusion, the film was wound around a casting drum having a surface temperature of 30 ° C. by using an electrostatic application casting method and cooled and solidified to produce an unstretched film. This unstretched film was heated to 100 ° C. with a heated roll group and an IR heater and stretched 3.5 times in the longitudinal direction. Next, the end of the uniaxial film is held with a clip and guided to a hot air zone heated at 130 ° C., stretched 4.0 times in the width direction, heat-treated at 210 ° C. for 5 seconds, and transversely at 130 ° C. 3% relaxation treatment.
[0154]
In this way, a laminated biaxially stretched polyester film of a polyester layer with a thickness of 5 μm containing 1000 ppm of calcium carbonate particles and a polyester layer with a thickness of 33 μm not containing particles was obtained.
[0155]
Next, in the same manner as in Example 4, a release layer was provided on the surface of the polyester layer not containing particles, and an antistatic layer was provided on the surface of the polyester layer containing calcium carbonate particles. A laminated biaxially stretched polyester film having release layers on separate surfaces was obtained. Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0156]
(Comparative Example 3)
Addition polymerization reaction type silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KS830) is dispersed in a solvent (toluene) so that the resin solid content concentration is 3% by weight, and 1 part by weight of platinum catalyst with respect to 100 parts by weight of silicone resin. Was added to prepare a coating solution containing a silicone resin. Next, a biaxially stretched polyester film having a thickness of 38 μm containing 200 ppm of aggregate silica particles having an average particle diameter of 1.0 μm is applied to one side of the film with a wire bar using a wire bar, Reaction curing and drying at 140 ° C. × 30 seconds, release film (application amount after drying of release layer: 0.05 g / m)²) Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0157]
(Comparative Example 4)
The amount of UV irradiation is 100mJ / cm²A release film having an antistatic layer was obtained in the same manner as in Example 4 except that the above was obtained. Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0158]
(Comparative Example 5)
The dry coating amount of the release layer is 0.5 g / m²A release film having an antistatic layer was obtained in the same manner as in Example 5 except that. Next, a release film with a ceramic sheet was obtained in the same manner as in Example 1 except that the thickness of the ceramic sheet layer was 2 μm.
[0159]
Table 2 shows the evaluation results of the release films with ceramic sheets obtained in Examples 4 to 7 and Comparative Examples 3 to 5.
[0160]
[Table 2]

[0161]
In Examples 4, 5, 6, and 7, the relationship between the dynamic hardness (A) of the ceramic sheet surface and the dynamic hardness (B) of the release layer surface is | A−B | ≦ 20, and the rub-off value is 5 or less. No peeling failure of the ceramic sheet was observed, the peeling charge of the ceramic sheet was 1 kV or less, the ceramic sheet and the release film were easily peeled off without reattachment, and the peeling surface of the ceramic sheet was also smooth Met.
[0162]
On the other hand, in Comparative Example 3, | A−B | ≦ 20 and the rub-off value was 5 or less, and no peeling failure of the ceramic sheet was observed, but the peeling charge of the ceramic sheet was larger than 5 kV, Reattachment of the sheet and the release film occurred. Further, the release surface of the ceramic sheet is transferred by the protrusions on the silicone release surface, and when the thickness of the ceramic sheet is reduced, it is expected that the thickness accuracy will be greatly affected.
[0163]
In Comparative Example 4, | A-B |> 20, the peel strength between the ceramic sheet and the release layer was large, and the rub-off value was also greater than 10, so the adhesion between the release layer and the polyester film was weak, and the ceramic Before the coating, the release layer was rubbed by a part of the coating equipment and dropped off, so that the ceramic sheet was completely torn at the time of peeling.
[0164]
In Comparative Example 5, | A-B |> 20, the peeling force with the ceramic sheet was increased, and the ceramic sheet was completely torn at the time of peeling.
[0165]
【The invention's effect】
According to the release film with a ceramic sheet of the present invention, the peeling force at the time of peeling is small, and in the peeling process at the time of manufacturing the ceramic sheet, the release film can be peeled and removed from the ceramic sheet with an appropriate force with no peeling failure. In addition, by controlling the surface unevenness of the release surface, a uniform ceramic sheet free from defects such as pinholes can be obtained particularly in the ceramic coating process during the production of the thin film ceramic sheet.
[0166]
Therefore, the release film with a ceramic sheet of the present invention is suitable for producing a ceramic sheet, particularly a thin film ceramic sheet.
[0167]
  In particular, the present inventionClaim 2The release film with a ceramic sheet according to the present invention further has good adhesion between the polyester film and the release layer, and in the peeling process during the production of the ceramic sheet, it is possible to eliminate the peeling failure due to scraping of the release layer. Since the peeling charge between the film and the release film is small, it is possible to prevent troubles of re-adhering after peeling. Further, since the smoothness of the release surface is extremely excellent, it is possible to process an ultra-thin ceramic sheet having a thickness of 3 μm or less with high thickness accuracy, and it is particularly suitable for the production of an ultra-thin ceramic sheet.

Claims (7)

And one side curable silicone resin to release layer provided comprising releasing main constituent film of a base film made of polyester film, the release parting layer ceramic sheet layer having a thickness of 3μm or less on the surface of the film A release film with a ceramic sheet formed by laminating
The base film is a polyester film having a single-layer structure containing particles in the film, or a laminated structure of at least two layers formed by laminating a particle-containing layer on the surface opposite to the release layer forming surface. A polyester film having
The absolute value of the difference between the dynamic hardness A of the ceramic sheet layer surface and the dynamic hardness B of the release layer surface satisfies the following formula (1), and ten points in the measurement of the three-dimensional surface roughness of the release layer surface A release film with a ceramic sheet, wherein the relationship between the average roughness SRz (μm) and the thickness C (μm) of the ceramic sheet satisfies the following formula (2).
| A-B | ≦ 20 (gf / μm ² ) (1)
SRz ≦ C / 2 (2) A release layer comprising a curable silicone resin as a main component on one side of a base film made of a polyester film, a release film having an antistatic layer on the other side, and a release layer surface of the release film A release film with a ceramic sheet formed by laminating a ceramic sheet layer having a thickness of 3 μm or less,
The base film is a polyester film having a laminated structure of at least two layers, in which a polyester film layer containing substantially no particles and a particle-containing layer are laminated on the surface opposite to the release layer forming surface. , before Symbol antistatic layer ten-point average roughness in a three-dimensional surface roughness measurement SRz ([mu] m), the average inclination gradient Esuderutaei, mean spatial wavelength S [lambda] ([mu] m) and number of protrusions PC satisfies the following formula in an area 0.12 mm ² ( 3) and (4) release film covered ceramic sheet according to claim 1, characterized by satisfying the.
0.05 ≦ SRz ≦ 0.5 (3)
SΔa × PC / Sλa ≧ 0.2 (4) The release film with a ceramic sheet according to claim 2, wherein the particle-containing layer is a coating layer mainly containing a polymer resin and particles. Release film with a ceramic sheet according to claim 2, wherein the particle-containing layer is a polyester film layer containing particles. Average particle diameter of 5μm or less of calcium carbonate particles of the particles, silica particles, crosslinked acrylic particles, crosslinked polystyrene particles, according to claim 1, 2, 3 or, characterized in that at least one selected from benzoguanamine particles 4. A release film with a ceramic sheet according to 4 . Particle size distribution ratio of the particles satisfies the following formula (5), the product of the average particle diameter and the particle content is characterized by satisfying the following expression (6) according to claim 1, 2, 3, 4 or 5. A release film with a ceramic sheet according to 5 .
0.2 ≦ D ₅₀ / D ₅ ≦ 0.6 (5)
150 ≦ D ₅₀ × E ≦ 10000 (6)
Here, in the formula, D ₅₀ is the particle diameter (μm) when the cumulative weight is 50%, D ₅ is the particle diameter (μm) when the cumulative weight is 5%, and E is the particle content (ppm). Each is shown. The peeling force (P10) measured after the release layer surface was subjected to 10 reciprocating frictions with the friction material between the release layer and the adhesive layer of the ceramic sheet adhered to the release layer surface, and the peeling measured before the friction. force (P0) and the ratio of (Rabuofu value (P10 / P0)) is, according to claim 2, 3, 4, 5 or 6 release film covered ceramic sheet, wherein the 10 or less.