JP4951157B2 - Antistatic film - Google Patents

Description

【００１７】
【化２】

【００１８】
［上記（１）、（２）式中、Ｒ_１は水素または炭素数１〜８のアルキル基であり、Ｒ_２は炭素数１〜８のアルキレン基、Ｒ_３、Ｒ_４およびＲ_５はそれぞれ独立して水素または炭素数１〜６のアルキル基、Ｘ⁻は陰イオンを表す］
また、アニオン性を示す構成単位としてはカルボン酸塩基を持つ化合物、硫酸エステル塩基を持つ化合物、スルホン酸塩基を持つ化合物、リン酸エステル塩基を持つ化合物などが挙げられるが、特にカルボン酸塩基を持つ化合物を選択すると、得られる塗布液に沈殿や凝集が生じにくい等の好ましい性質が得られる。具体的な例としては、下記の（３）式で示されるようなものが挙げられる。
【００１９】
【化３】

【００２０】
［上記（３）式中、Ｒ_１は水素または炭素数１〜８のアルキル基であり、Ｍは水素または陽イオンを表す］
またあるいは、両性高分子化合物のカチオン性基とアニオン性基は、別々の構成単位ではなく、同一の単位中にともに含まれている場合もある。この場合例えば、下記（４）式、（５）式のような化合物を例示できる。
【００２１】
【化４】

【００２２】
【化５】

【００２３】
［上記（４）、（５）式中、Ｒ_１は水素または炭素数１〜８のアルキル基であり、Ｒ_２は炭素数１〜８のアルキレン基、Ｒ_３およびＲ_４はそれぞれ独立して水素または炭素数１〜６のアルキル基、Ｒ_５は炭素数１〜４のアルキレン基、Ｘ⁻は陰イオン、Ｍは水素または陽イオンを表す］
【００２４】
本発明においては、これらの化合物を組み合わせて両性高分子化合物とすることができるが、カチオン性基とアニオン性基の含有量が大きく異なることは好ましくない。通常は、一分子内でカチオン性基１００モルに対し、アニオン性基が５０〜２００モルの間、好ましくは８０〜１２５モルの間である。両者の含有量が上記範囲を外れると、帯電防止性能が悪化したり、塗布液に沈殿や凝集が生じにくいという特性が失われたりする。
また、本発明においては、両性高分子化合物の数平均分子量は、通常は１０００以上であり、好ましくは２０００以上、さらに好ましくは５０００以上である。分子量がこの範囲より低い場合は、塗布層中から容易に除去されて経時的に性能の低下を引き起こしたり、塗布層がべたついたりするおそれがある。また、分子量が低いと耐熱安定性に劣る場合もある。
【００２５】
一方、両性高分子化合物の分子量が高すぎる場合は、塗布液の粘度が高くなりすぎて塗工性を悪化させる等の不具合を生じる場合がある。そのような不具合を生じないためには、数平均分子量が５０００００以下、好ましくは１０００００以下であることが好ましい。
本発明で用いる塗布液には、ポリエステル樹脂、アクリル樹脂およびポリウレタン樹脂の中から選択される１種以上の樹脂を含有することができる。これらの樹脂をバインダー樹脂として含有することで、得られる塗布層の強度や基材フィルムへの密着性を向上することができる。通常用いられるイオン性高分子帯電防止剤では、その種類によっては、かかるバインダー樹脂との混合安定性が悪く、使用できないことがままあった。しかし、本発明で用いる帯電防止剤はそのような欠点が改良されているため、用途に合わせて種々のバインダー樹脂の中から適したものを選択できる。
【００２６】
塗布液成分としてのポリエステル樹脂を構成する成分として、下記のような多価カルボン酸および多価ヒドロキシ化合物を例示できる。すなわち、多価カルボン酸としては、テレフタル酸、イソフタル酸、オルトフタル酸、フタル酸、４，４’−ジフェニルジカルボン酸、２，５−ナフタレンジカルボン酸、２，６−ナフタレンジカルボン酸、１，４−シクロヘキサンジカルボン酸、２−カリウムスルホテレフタル酸、５−ソジウムスルホイソフタル酸、アジピン酸、アゼライン酸、セバシン酸、ドデカンジカルボン酸、グルタル酸、コハク酸、トリメリット酸、トリメシン酸、無水トリメリット酸、無水フタル酸、ｐ−ヒドロキシ安息香酸、トリメリット酸モノカリウム塩およびそれらのエステル形成性誘導体などを用いることができ、多価ヒドロキシ化合物としては、エチレングリコール、１，２−プロピレングリコール、１，３−プロピレングリコール、１，３−プロパンジオール、１，４−ブタンジオール、１，６−ヘキサンジオール、２−メチル−１，５−ペンタンジオール、ネオペンチルグリコール、１，４−シクロヘキサンジメタノール、ｐ−キシリレングリコール、ビスフェノールＡ−エチレングリコール付加物、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、ポリプロピレングリコール、ポリテトラメチレングリコ、ールポリテトラメチレンオキシドグリコール、ジメチロールプロピオン酸、グリセリン、トリメチロールプロパン、ジメチロールエチルスルホン酸ナトリウム、ジメチロールプロピオン酸カリウムなどを用いることができる。常法の重縮合反応によってポリエステルを合成することができる。
【００２７】
なお、上記のほか、特開平１−１６５６３３号公報に記載されている、いわゆるアクリルグラフトポリエステルや、ポリエステルポリオールをイソシアネートで鎖延長したポリエステルポリウレタンなどの、ポリエステル成分を有する複合高分子も本発明で用いる塗布剤ポリエステルに含まれる。
本発明で用いる、塗布液成分としてのアクリル樹脂とは、アクリル系、メタアクリル系のモノマーに代表されるような、炭素−炭素二重結合を持つ重合性モノマーからなる重合体である。これらは、単独重合体あるいは共重合体いずれでも差し支えない。また、それら重合体と他のポリマー（例えばポリエステル、ポリウレタン等）との共重合体も含まれる。例えば、ブロック共重合体、グラフト共重合体である。あるいは、ポリエステル溶液、またはポリエステル分散液中で炭素−炭素二重結合を持つ重合性モノマーを重合して得られたポリマー（場合によってはポリマーの混合物）も含まれる。同様にポリウレタン溶液、ポリウレタン分散液中で炭素−炭素二重結合を持つ重合性モノマーを重合して得られたポリマー(場合によってはポリマーの混合物）も含まれる。同様にして他のポリマー溶液、または分散液中で炭素−炭素二重結合を持つ重合性モノマーを重合して得られたポリマー（場合によってはポリマー混合物）も含まれる。
【００２８】
上記炭素−炭素二重結合を持つ重合性モノマーとしては、特に限定はしないが、特に代表的な化合物としては、例えば以下のようなものである。
アクリル酸、メタクリル酸、クロトン酸、イタコン酸、フマル酸、マレイン酸、シトラコン酸のような各種カルボキシル基含有モノマー類、およびそれらの塩；２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシプロピル（メタ）アクリレート、４−ヒドロキシブチル（メタ）アクリレート、モノブチルヒドロキルフマレート、モノブチルヒドロキシイタコネートのような各種の水酸基含有モノマー類；メチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、ブチル（メタ）アクリレート、ラウリル（メタ）アクリレートのような各種の（メタ）アクリル酸エステル類；（メタ）アクリルアミド、ジアセトンアクリルアミド、Ｎ−メチロールアクリルアミドまたは（メタ）アクリロニトリル等のような種々の窒素含有ビニル系モノマー類。また、これらと併用して以下に示すような重合性モノマーを共重合することができる。すなわち、スチレン、α−メチルスチレン、ジビニルベンゼン、ビニルトルエンのような各種スチレン誘導体、酢酸ビニル、プロピオン酸ビニルのような各種のビニルエステル類；γ−メタクリロキシプロピルトリメトキシシラン、ビニルトリメトキシシラン、チッソ（株）製「サイラプレーンＦＭ−０７」（メタクリロイルシリコンマクロマー）等のような種々の珪素含有重合性モノマー類；燐含有ビニル系モノマー類；塩化ビニル、塩化ビリデン、フッ化ビニル、フッ化ビニリデン、トリフルオロクロルエチレン、テトラフルオロエチレン、クロロトリフルオロエチレン、ヘキサフルオロプロピレンのような各種のハロゲン化ビニル類；ブタジエンのような各種共役ジエン類。
【００２９】
塗布液成分としてのポリウレタン樹脂としては、例えば、特公昭４２−２４１９４号公報、特公昭４６−７７２０号公報、特公昭４６−１０１９３号公報、特公昭４９−３７８３９号公報、特開昭５０−１２３１９７号公報、特開昭５３−１２６０５８号公報、特開昭５４−１３８０９８号公報等に開示された公知のポリウレタンまたはそれらに準じたポリウレタンを使用することができる。
例えば、ポリイソシアネートとしては、トリレンジイソシアネート、フェニレンジイソシアネート、４，４′−ジフェニルメタンジイソシアネート、ヘキサメチレンジイソシアネート、キシリレンジイソシアネート、４，４′−ジシクロヘキシルメタンジイソシアネート、イソホロンジイソシアネート等を挙げることができる。
【００３０】
また、ポリオールとしては、ポリオキシエチレングリコール、ポリオキシプロピレングリコール、ポリオキシテトラメチレングリコール等のポリエーテルポリオール類、ポリエチレンアジペート、ポリエチレン−ブチレンアジペート、ポリカプロラクトン等のポリエステルポリオール類、アクリル系ポリオール、ひまし油等を挙げることができる。通常、分子量３００〜２０００のポリオールが使用される。特に、ポリエステルポリオールを使用すると、塗膜の透明性、上塗り剤との接着性が向上して好ましい。
また、鎖長延長剤あるいは架橋剤としては、エチレングリコール、プロピレングリコール、ブタンジオール、ジエチレングリコール、トリメチロールプロパン、ヒドラジン、エチレンジアミン、ジエチレントリアミン、４，４′−ジアミノジフェニルメタン、４，４′−ジアミノジシクロヘキシルメタン、水等を挙げることができる。
【００３１】
さらに本発明で使用する塗布液中には、必要に応じて、架橋反応性化合物を含んでいてもよい。架橋反応性化合物は主に、他の樹脂や化合物に含まれる官能基と架橋反応することで、塗布層の凝集性、表面硬度、耐擦傷性、耐溶剤性、耐水性を改良することができる。
本発明で使用する塗布液は、界面活性剤、消泡剤、塗布性改良剤、増粘剤、有機系潤滑剤、有機粒子、無機粒子、酸化防止剤、紫外線吸収剤、発泡剤、染料、顔料等の添加剤を含有していてもよい。これらの添加剤は単独で用いてもよいが、必要に応じて二種以上を併用してもよい。
本発明における塗布液は、取扱い上、作業環境上、水溶液または水分散液であることが望ましいが、水を主たる媒体としており、本発明の要旨を越えない範囲であれば、有機溶剤を含有していてもよい。
【００３２】
塗布液の固形分濃度には特に制限はないが、通常０．３〜６５重量％、好ましくは０．５〜３０重量％、さらに好ましくは１〜２０重量％である。濃度がこれらの範囲より高すぎる場合も低すぎる場合も、機能を十分に発現するために必要な厚さの塗布層を設けることが困難となることがある。
塗布層の厚さは乾燥厚さで、通常０．００３〜１．５μｍ、好ましくは０．００５〜０．５μｍ、さらに好ましくは０．０１〜０．３μｍである。塗布層の厚さが０．００３μｍ未満の場合は十分な性能が得られない恐れがあり、１．５μｍを超えるとフィルム同士のブロッキングが起こりやすくなる。
【００３３】
ポリエステルフィルムに塗布層を設ける方法として、特にポリエステルフィルムを製造する工程中で塗布液を塗布する方法が、経済性およびその特性の面から好適に採用される。例えば、未延伸フィルムに塗布した後延伸する方法、一軸延伸フィルムに塗布した後延伸する方法、二軸延伸フィルムに塗布した後延伸する方法等がある。特に、未延伸または一軸延伸フィルムに塗布液を塗布した後、テンターにおいて乾燥および延伸を同時に行う方法が経済的である。
ポリエステルフィルムに塗布液を塗布する方法としては、通常用いられる塗布方式が適用できる。例えば、１９９９年、技術情報協会発行、「コーティング技術」に示されるような、具体的には、グラビアコーター、ブレードコーター、ロッドコーター、ダイコーター、スプレイコーター、カーテンコーター等、あるいはその他の塗布技術が挙げられる。
【００３４】
【実施例】
以下に実施例を挙げて本発明をさらに詳細に説明するが、本発明はその要旨を越えない限り、以下の実施例に限定されるものではない。なお、実施例および比較例における評価方法は下記のとおりである。
【００３５】
（１）塗布液安定性
以下の実施例および比較例で用いた塗布液を、固形分濃度５ｗｔ％に調整し、栓付き硝子瓶に入れて２３℃の環境下で４８時間静置した後、目視にて液の状態を観察して以下の基準にて評価した。
○：液の外観に著しい変化が見られない。
×：液に凝集、沈殿などの異常が見られ、塗布に適さない。
【００３６】
（２）表面固有抵抗値
日本ヒューレット・パッカード社製高抵抗測定器：ＨＰ４３３９Ｂおよび測定電極：ＨＰ１６００８Ｂを使用し、２３℃，５０％ＲＨの測定雰囲気でサンプルを充分調湿後、印可電圧１００Ｖで１分後の塗布層の表面固有抵抗値を測定した。測定した値は以下の基準で評価した。
○：良好。表面固有抵抗値が１×１０^１１Ω以下。
△：普通。表面固有抵抗値が１×１０^１４Ω以下で１×１０^１１Ωより高い。
×：不良。表面固有抵抗値が１×１０^１４Ωより高い。
【００３７】
実施例および比較例において、塗布液を構成する成分として使用した化合物は、以下のとおりである。
・帯電防止剤（Ａ−１）
前記（１）式中の、Ｒ_１がメチル基、Ｒ_２がエチレン基、Ｒ_３、Ｒ_４、Ｒ_５がメチル基、Ｘ⁻が−ＣＨ_３ＯＳＯ_３ ⁻であるような化合物（ａｃ−１）、前記（３）式中のＲ_１が水素、Ｍが２−ヒドロキシエチル−トリメチルアンモニウムであるような化合物（ａａ−１）およびメチルアクリレート（ａｏ−１）を、モル比で２／２／１の割合で共重合して得られた、数平均分子量が１２，０００の化合物。
【００３８】
・帯電防止剤（Ａ−２）〜（Ａ−６）
（Ａ−１）と準する製造方法で、下記表１に示す組成を有する帯電防止剤（Ａ−２）〜（Ａ−６）を得た。
【００３９】
【表１】

ただし、表１に示した構成単位は下記表２に示す化合物を指す。
【００４０】
【表２】

【００４１】
・帯電防止剤（Ａ−７）、（Ａ−８）
以下の表３に示す化合物を帯電防止剤（Ａ−７）、（Ａ−８）とした。
【００４２】
【表３】

ただし、表３に示した構成単位は、上記の表２で示した化合物を指す。
【００４３】
・ポリエステル樹脂（Ｂ−１）
スルホン酸ナトリウム塩水分散型ポリエステル樹脂である、大日本インキ化学工業製ファインテックス
・不活性粒子（Ｓ−１）
平均粒径０．０５μｍのシリカゾル
【００４４】
実施例１
固有粘度０．６５のポリエチレンテレフタレートのチップを十分に乾燥した後、２８０〜３００℃に加熱溶融し、Ｔ字型口金よりシート状に押し出し、静電密着法を用いて表面温度４０〜５０℃の鏡面冷却ドラムに密着させながら冷却固化させて、未延伸ポリエチレンテレフタレートフィルムを作成した。このフィルムを８５℃の加熱ロール群を通過させながら長手方向に３．７倍延伸し、一軸配向フィルムとした。この一軸配向フィルムの片面に、下記表４に示すとおりの塗布液をメイヤーバーにより塗布した。そのフィルムをテンター延伸機に導き、１００℃で幅方向に４．０倍延伸し、さらに２３０℃で熱処理を施し、フィルム厚みが５０μｍの基材フィルムの上に０．０５ｇ／ｍ^２の量の塗布層を設けた積層二軸延伸配向ポリエチレンテレフタレートフィルムを得た。
【００４５】
実施例２〜６
実施例１において、塗布液の内容を下記表４に示すとおりに変更した以外は同様にして、厚みが５０μｍの基材フィルムの上に０．０５ｇ／ｍ^２の量の塗布層を設けた積層二軸延伸配向ポリエチレンテレフタレートフィルムを得、それぞれ実施例２〜実施例６とした。
【００４６】
比較例１〜２
実施例１において、塗布液の内容を下記表４に示すとおりに変更した以外は同様にして、厚みが５０μｍの基材フィルムの上に０．０５ｇ／ｍ^２の量の塗布層を設けた積層二軸延伸配向ポリエチレンテレフタレートフィルムを得、それぞれ比較例１、比較例２とした。
【００４７】
【表４】

なお、いずれの塗布液も水を主たる媒体とする水溶液または水分散液である。
【００４８】
以上にて得られたフィルムの評価特性を下記表５に示す。
【００４９】
【表５】

比較例１、比較例２は、塗布液が凝集し塗布を行うことが不能であった。
【００５０】
【発明の効果】
本発明によれば、ポリエステルフィルムに優れた帯電防止性能を持つ塗布層を設けることができ、また従来技術と異なり、その塗布層と基材フィルムの密着性を向上させるための手法に対する制限が少ないため、その工業的な利用価値は高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antistatic film. More specifically, the present invention relates to a polyester film having a coating layer excellent in antistatic performance and adhesion to a substrate film.
[0002]
[Prior art]
Biaxially stretched polyester film has excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, and transparency, so it can be used as a base film for magnetic recording media, film for plate making, and packaging. It is used for a wide range of applications including films and optical films.
However, a common problem with plastic films is that they are easily charged with static electricity. This causes problems such as poor running performance of the processed product or processed product and attracting dust around the film.
[0003]
In general, as an antistatic method for a polyester film, a method of kneading a low molecular weight anionic surfactant type compound such as an organic sulfonate, a method of depositing a metal compound, an anionic compound or a cationic compound, or a so-called There is a method of applying a conductive compound to the surface (Patent Document 1).
Although the method of kneading an anionic compound has the advantage that it can be manufactured at low cost, it has a limit in the antistatic effect. In addition, since low molecular weight compounds are used, anionic compounds gather on the surface of the polyester film due to so-called blooming, and the adhesive force between the polyester film and the overcoat layer is reduced, or the anionic compounds are transferred to the film or transport roll. Occurs. For this reason, the durability of the antistatic performance is also lowered.
[0004]
The method of vapor-depositing a metal compound has excellent antistatic properties, and in recent years the application has been expanded as a transparent conductive film, but the production cost is high and suitable for specific applications, but as a general antistatic film Is difficult to use.
The method of applying a conductive compound such as conductive carbon has an advantage that the antistatic effect is relatively good and can be manufactured at a relatively low cost, but the transparency of the film is deteriorated.
Although a method of applying a high molecular weight anionic compound as an antistatic agent to a film is an excellent method with few such disadvantages, an anionic compound exhibits high antistatic properties under high humidity, but is low There is a problem that the performance is extremely deteriorated under humidity.
[0005]
On the other hand, a method of applying a high molecular weight cationic compound to a film has been widely adopted as an antistatic method for polyester films because the deterioration of antistatic performance is relatively small even under low humidity.
However, many of these compounds have a disadvantage that they are easily removed from the film surface by abrasion or water washing because they are poor in adhesion and water resistance with the film as a substrate.
[0006]
In order to improve this defect, there is a method of introducing a binder resin as a component of the coating layer. However, many of the cationic compounds have poor compatibility and mixing stability with commonly used binder resins, so that they cannot be applied neatly or the desired performance cannot be obtained. It is a problem that agglomerates and cannot be used.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 47-21383
[Problems to be solved by the invention]
This invention is made | formed in view of the said situation, Comprising: The solution subject is providing the polyester film which has the coating layer excellent in the antistatic performance and also excellent in the adhesiveness to a base film.
[0009]
[Means for Solving the Problems]
As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by providing a coating layer using a specific type of compound as an antistatic agent, thereby completing the present invention. It came to do. That is, the gist of the present invention is a film obtained by coating a polyester film with a coating solution containing an amphoteric polymer compound, and the amphoteric polymer compound has a carboxylate as an anionic group and a cationic group. having a quaternary ammonium base as a constituent unit, a compound ratio satisfies the following formula with a cationic group and an anionic group in one molecule, a constituent unit other than the cationic structural units and anionic constituent unit, the It exists in the antistatic film characterized by containing in the range of 1 / 18-1 / 5 mol in the molar ratio among the structural units of a compound .
0.5 ≦ (amount of cationic group) / (amount of anionic group) ≦ 1.0
(In the above formula, the amount of each group is mol)
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The polyester constituting the polyester film of the present invention is a polyester obtained by polycondensation of a dicarboxylic acid component and a glycol component. Examples of these dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid, Examples of the glycol component include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like.
[0011]
Typical examples of the polyester used in the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. The polyester which copolymerized may be sufficient and may contain the other component and additive as needed.
The polyester film in the present invention may contain particles for the purpose of imparting slipperiness for easy handling. Examples of such particles include inorganic particles such as silica, calcium carbonate, magnesium carbonate, calcium phosphate, kaolin, talc, aluminum oxide, titanium oxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide. Further, organic particles such as crosslinked polymer particles and calcium oxalate, and precipitated particles during the polyester production process can be used.
[0012]
The particle size and content of the particles to be used are selected according to the use and purpose of the film, but the average particle size is usually in the range of 0.005 to 5.0 μm, preferably 0.01 to 3.0 μm. is there. If the average particle size exceeds 5.0 μm, the surface roughness of the film becomes too rough, or the particles are likely to fall off from the film surface. If the average particle size is less than 0.005 μm, the surface roughness is too small and sufficient slipperiness may not be obtained. About particle | grain content, it is 0.001 to 30.0 weight% normally with respect to polyester, Preferably it is 0.01 to 10.0 weight%. When the amount of particles increases, the mechanical properties and transparency of the film tend to be impaired, and when the amount is small, the slipperiness tends to be inferior.
[0013]
Moreover, you may add an additive other than said particle | grain as needed. Examples of such additives include an antistatic agent, a stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, an antioxidant, a dye, a pigment, a light blocking agent, and an ultraviolet absorber.
The polyester film in the present invention may have a multilayer structure as long as the requirements of the present invention are satisfied, and in that case, a layer that is not polyester may be included. In addition, the coating layer is naturally included in the concept of the present invention, whether it is provided on only one side of the film or on both sides.
[0014]
Next, the compound which is a component which comprises the coating layer of the film of this invention is described.
In the present invention, the amphoteric polymer compound used as an antistatic agent refers to a polymer compound having a group that exhibits ionization upon ionization and a group that exhibits anionic property. In this case, each of the cationic group and the anionic group is not necessarily one kind, and other components may be copolymerized.
Examples of such amphoteric polymer compounds include compounds each having a structural unit exhibiting cationic properties and a structural unit exhibiting anionic properties.
[0015]
As the structural unit exhibiting cationic properties, a unit having a quaternary ammonium base is particularly preferably selected, and specific examples include those represented by the following formulas (1) and (2).
[0016]
[Chemical 1]

[0017]
[Chemical formula 2]

[0018]
[In the above formulas (1) and (2), R ₁ is hydrogen or an alkyl group having 1 to 8 carbon atoms, R ₂ is an alkylene group having 1 to 8 carbon atoms, R ₃ , R ₄ and R ₅ are each Independently hydrogen or an alkyl group having 1 to 6 carbon atoms, X ⁻ represents an anion]
Further, examples of the anionic structural unit include a compound having a carboxylate group, a compound having a sulfate ester base, a compound having a sulfonate group, a compound having a phosphate ester base, and the like. When a compound is selected, preferable properties such as precipitation and aggregation are hardly generated in the obtained coating solution. Specific examples include those represented by the following formula (3).
[0019]
[Chemical 3]

[0020]
[In the above formula (3), R ₁ represents hydrogen or an alkyl group having 1 to 8 carbon atoms, and M represents hydrogen or a cation.]
Alternatively, the cationic group and the anionic group of the amphoteric polymer compound may be contained together in the same unit, not as separate structural units. In this case, for example, compounds such as the following formulas (4) and (5) can be exemplified.
[0021]
[Formula 4]

[0022]
[Chemical formula 5]

[0023]
[In the above formulas (4) and (5), R ₁ is hydrogen or an alkyl group having 1 to 8 carbon atoms, R ₂ is an alkylene group having 1 to 8 carbon atoms, and R ₃ and R ₄ are each independently Hydrogen or an alkyl group having 1 to 6 carbon atoms, R ₅ represents an alkylene group having 1 to 4 carbon atoms, X ⁻ represents an anion, and M represents hydrogen or a cation.]
[0024]
In the present invention, these compounds can be combined to form an amphoteric polymer compound, but it is not preferable that the contents of the cationic group and the anionic group differ greatly. Usually, the anionic group is between 50 and 200 mol, preferably between 80 and 125 mol, per 100 mol of the cationic group in one molecule. If the content of both is out of the above range, the antistatic performance is deteriorated, or the property that precipitation or aggregation hardly occurs in the coating solution is lost.
In the present invention, the number average molecular weight of the amphoteric polymer compound is usually 1000 or more, preferably 2000 or more, more preferably 5000 or more. When the molecular weight is lower than this range, it may be easily removed from the coating layer to cause deterioration in performance over time, or the coating layer may become sticky. Moreover, when the molecular weight is low, the heat stability may be inferior.
[0025]
On the other hand, if the molecular weight of the amphoteric polymer compound is too high, the viscosity of the coating solution may become too high, resulting in problems such as worsening the coatability. In order not to cause such a problem, the number average molecular weight is preferably 500,000 or less, more preferably 100,000 or less.
The coating liquid used in the present invention can contain one or more resins selected from polyester resins, acrylic resins, and polyurethane resins. By containing these resins as a binder resin, the strength of the resulting coating layer and the adhesion to the substrate film can be improved. Depending on the type of ionic polymer antistatic agent that is usually used, mixing stability with such a binder resin is poor, and it remains unusable. However, the antistatic agent used in the present invention is improved in such drawbacks, so that a suitable one can be selected from various binder resins according to the application.
[0026]
Examples of components constituting the polyester resin as the coating solution component include the following polyvalent carboxylic acids and polyvalent hydroxy compounds. That is, as polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4- Cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, trimellitic anhydride, Phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and ester-forming derivatives thereof can be used. Examples of polyvalent hydroxy compounds include ethylene glycol, 1,2-propylene glycol, 1,3 -Propylene glycol, 1,3-propane Diol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol Adducts, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ole polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, dimethylolpropionic acid Potassium etc. can be used. Polyester can be synthesized by a conventional polycondensation reaction.
[0027]
In addition to the above, composite polymers having a polyester component such as so-called acrylic graft polyester described in JP-A-1-165633 and polyester polyurethane obtained by chain-extending polyester polyol with isocyanate are also used in the present invention. Included in the coating polyester.
The acrylic resin as a coating solution component used in the present invention is a polymer composed of a polymerizable monomer having a carbon-carbon double bond, as typified by acrylic and methacrylic monomers. These may be either a homopolymer or a copolymer. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyurethane solution or polyurethane dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in another polymer solution or dispersion (in some cases, a polymer mixture) is also included.
[0028]
The polymerizable monomer having a carbon-carbon double bond is not particularly limited, but particularly typical compounds include, for example, the following.
Various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, and salts thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ) Various hydroxyl group-containing monomers such as acrylate, 4-hydroxybutyl (meth) acrylate, monobutylhydroxy fumarate, monobutylhydroxy itaconate; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) Various (meth) acrylic esters such as acrylate, butyl (meth) acrylate, lauryl (meth) acrylate; (meth) acrylamide, diacetone acrylamide, N-methylol acrylamide or (meth) acrylonitrile Various nitrogen-containing vinyl monomers such as. Further, in combination with these, polymerizable monomers as shown below can be copolymerized. Namely, various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene and vinyltoluene, various vinyl esters such as vinyl acetate and vinyl propionate; γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, Various silicon-containing polymerizable monomers such as “Silaplane FM-07” (methacryloyl silicon macromer) manufactured by Chisso Corporation; phosphorus-containing vinyl monomers; vinyl chloride, biridene chloride, vinyl fluoride, vinylidene fluoride Various vinyl halides such as trifluorochloroethylene, tetrafluoroethylene, chlorotrifluoroethylene and hexafluoropropylene; various conjugated dienes such as butadiene.
[0029]
Examples of the polyurethane resin as the coating solution component include, for example, JP-B-42-24194, JP-B-46-7720, JP-B-46-10193, JP-B-49-37839, JP-A-50-123197. Known polyurethanes disclosed in JP-A Nos. 53-126058, 54-138098, and the like, or polyurethanes based thereon can be used.
For example, examples of the polyisocyanate include tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.
[0030]
Polyols include polyether polyols such as polyoxyethylene glycol, polyoxypropylene glycol, and polyoxytetramethylene glycol, polyester polyols such as polyethylene adipate, polyethylene-butylene adipate, and polycaprolactone, acrylic polyols, castor oil, etc. Can be mentioned. Usually, a polyol having a molecular weight of 300 to 2000 is used. In particular, the use of a polyester polyol is preferable because the transparency of the coating film and the adhesiveness to the top coat are improved.
Examples of the chain extender or crosslinking agent include ethylene glycol, propylene glycol, butanediol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodicyclohexylmethane, Water etc. can be mentioned.
[0031]
Furthermore, the coating liquid used in the present invention may contain a crosslinking reactive compound as required. The cross-linking reactive compound mainly improves the cohesiveness, surface hardness, scratch resistance, solvent resistance, and water resistance of the coating layer by cross-linking reaction with functional groups contained in other resins and compounds. .
Coating liquids used in the present invention are surfactants, antifoaming agents, coating property improving agents, thickeners, organic lubricants, organic particles, inorganic particles, antioxidants, ultraviolet absorbers, foaming agents, dyes, You may contain additives, such as a pigment. These additives may be used alone or in combination of two or more as necessary.
The coating solution in the present invention is preferably an aqueous solution or an aqueous dispersion in terms of handling and working environment, but contains water as the main medium and contains an organic solvent as long as it does not exceed the gist of the present invention. It may be.
[0032]
Although there is no restriction | limiting in particular in the solid content density | concentration of a coating liquid, Usually, 0.3 to 65 weight%, Preferably it is 0.5 to 30 weight%, More preferably, it is 1 to 20 weight%. When the concentration is too high or too low than these ranges, it may be difficult to provide a coating layer having a thickness necessary for fully expressing the function.
The thickness of the coating layer is a dry thickness, and is usually 0.003 to 1.5 μm, preferably 0.005 to 0.5 μm, and more preferably 0.01 to 0.3 μm. If the thickness of the coating layer is less than 0.003 μm, sufficient performance may not be obtained, and if it exceeds 1.5 μm, blocking between films tends to occur.
[0033]
As a method of providing a coating layer on a polyester film, a method of applying a coating solution particularly in the process of producing a polyester film is preferably employed from the viewpoint of economy and characteristics. For example, there are a method of stretching after coating on an unstretched film, a method of stretching after coating on a uniaxially stretched film, a method of stretching after coating on a biaxially stretched film, and the like. In particular, it is economical to apply a coating solution to an unstretched or uniaxially stretched film and then perform drying and stretching simultaneously in a tenter.
As a method for applying the coating solution to the polyester film, a commonly used coating method can be applied. For example, as shown in “Coating Technology” issued by the Technical Information Association in 1999, specifically, gravure coaters, blade coaters, rod coaters, die coaters, spray coaters, curtain coaters, etc. Can be mentioned.
[0034]
【Example】
The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method in an Example and a comparative example is as follows.
[0035]
(1) Stability of coating solution The coating solutions used in the following examples and comparative examples were adjusted to a solid content concentration of 5 wt%, placed in a stoppered glass bottle and allowed to stand for 48 hours in an environment of 23 ° C. The state of the liquid was visually observed and evaluated according to the following criteria.
○: No significant change is observed in the appearance of the liquid.
X: Abnormalities such as aggregation and precipitation are observed in the liquid, which is not suitable for coating.
[0036]
(2) Surface resistivity value A high resistance measuring instrument manufactured by Hewlett-Packard Japan: HP4339B and measuring electrode: HP16008B were used, and the sample was sufficiently conditioned in a measurement atmosphere of 23 ° C. and 50% RH, and then 1 at an applied voltage of 100V. The surface specific resistance value of the coating layer after a minute was measured. The measured value was evaluated according to the following criteria.
○: Good. The surface resistivity is 1 × 10 ¹¹ Ω or less.
Δ: Normal. The surface resistivity is 1 × 10 ¹⁴ Ω or less and higher than 1 × 10 ¹¹ Ω.
X: Defect. The surface resistivity is higher than 1 × 10 ¹⁴ Ω.
[0037]
In the examples and comparative examples, the compounds used as components constituting the coating liquid are as follows.
・ Antistatic agent (A-1)
In the formula (1), a compound in which R ₁ is a methyl group, R ₂ is an ethylene group, R ₃ , R ₄ and R ₅ are methyl groups, and X ⁻ is —CH ₃ OSO ₃ ^— (ac-1 ), A compound (aa-1) in which R ₁ in the formula (3) is hydrogen and M is 2-hydroxyethyl-trimethylammonium and methyl acrylate (ao-1) in a molar ratio of 2/2 / A compound having a number average molecular weight of 12,000 obtained by copolymerization at a ratio of 1.
[0038]
・ Antistatic agents (A-2) to (A-6)
Antistatic agents (A-2) to (A-6) having the compositions shown in Table 1 below were obtained by a production method similar to (A-1).
[0039]
[Table 1]

However, the structural unit shown in Table 1 refers to the compound shown in Table 2 below.
[0040]
[Table 2]

[0041]
・ Antistatic agents (A-7), (A-8)
The compounds shown in Table 3 below were designated as antistatic agents (A-7) and (A-8).
[0042]
[Table 3]

However, the structural unit shown in Table 3 refers to the compound shown in Table 2 above.
[0043]
・ Polyester resin (B-1)
Fine tex and inert particles (S-1) manufactured by Dainippon Ink & Chemicals, Inc., a sodium sulfonate aqueous dispersion type polyester resin
Silica sol with an average particle size of 0.05 μm
Example 1
After sufficiently drying a polyethylene terephthalate chip having an intrinsic viscosity of 0.65, it is heated and melted to 280 to 300 ° C., extruded into a sheet form from a T-shaped die, and has a surface temperature of 40 to 50 ° C. using an electrostatic adhesion method. It was allowed to cool and solidify while closely contacting the mirror surface cooling drum to prepare an unstretched polyethylene terephthalate film. This film was stretched 3.7 times in the longitudinal direction while passing through a heating roll group at 85 ° C. to obtain a uniaxially oriented film. A coating solution as shown in Table 4 below was applied to one side of this uniaxially oriented film with a Mayer bar. The film was guided to a tenter stretching machine, stretched 4.0 times in the width direction at 100 ° C., and further subjected to heat treatment at 230 ° C., on a base film having a film thickness of 50 μm in an amount of 0.05 g / m ² . A laminated biaxially oriented polyethylene terephthalate film provided with a coating layer was obtained.
[0045]
Examples 2-6
In Example 1, except that the content of the coating solution was changed as shown in Table 4 below, a laminate in which a coating layer having an amount of 0.05 g / m ² was provided on a base film having a thickness of 50 μm Biaxially stretched and oriented polyethylene terephthalate films were obtained and designated as Examples 2 to 6, respectively.
[0046]
Comparative Examples 1-2
In Example 1, except that the content of the coating solution was changed as shown in Table 4 below, a laminate in which a coating layer having an amount of 0.05 g / m ² was provided on a base film having a thickness of 50 μm A biaxially oriented polyethylene terephthalate film was obtained, which was referred to as Comparative Example 1 and Comparative Example 2, respectively.
[0047]
[Table 4]

Each of the coating liquids is an aqueous solution or water dispersion containing water as a main medium.
[0048]
The evaluation characteristics of the film obtained above are shown in Table 5 below.
[0049]
[Table 5]

In Comparative Example 1 and Comparative Example 2, the coating solution was agglomerated and could not be applied.
[0050]
【Effect of the invention】
According to the present invention, a coating layer having excellent antistatic performance can be provided on a polyester film, and unlike the prior art, there are few restrictions on the method for improving the adhesion between the coating layer and the substrate film. Therefore, its industrial utility value is high.

Claims (3)

A film obtained by coating a polyester film with a coating solution containing an amphoteric polymer compound, the amphoteric polymer compound comprising a carboxylic acid salt as an anionic group and a quaternary ammonium base as a cationic group And the ratio of the cationic group to the anionic group in one molecule satisfies the following formula, and the structural unit other than the cationic structural unit and the anionic structural unit is a mole of the structural unit of the compound. An antistatic film comprising a ratio of 1/18 to 1/5 mol .
0.5 ≦ (amount of cationic group) / (amount of anionic group) ≦ 1.0
(In the above formula, the amount of each group is mol)   2. The antistatic film according to claim 1, wherein the coating solution contains at least one resin selected from a polyester resin, an acrylic resin, and a polyurethane resin.   The antistatic film according to claim 1, wherein the antistatic layer is dried and stretched after an aqueous coating solution is applied.