JP3849810B2 - Reversible thermochromic recording material and reversible thermochromic recording medium - Google Patents

Description

【０００８】
（式中Ｒは、Ｃ₃以上のアルキル基である）
２． 発消色制御ポリマーがガラス転移温度が６０℃以下である、１項に記載された可逆性熱変色記録材料。
３． １項または２項に記載された可逆性熱変色記録材料からなる可逆性熱変色記録層を支持体上に設けてなる可逆性熱変色記録媒体。
４． 可逆性熱変色記録層および支持体の間に、密着性を向上するアンダーコート層を設けてなる、３項に記載された可逆性熱変色記録媒体。
５． 可逆性熱変色記録層上に保護層を設けてなる、３項または４項に記載された可逆性熱変色記録媒体。
６． 保護層が透明なポリマーよりなる、５項に記載された可逆性熱変色記録媒体。
７． 可逆性熱変色記録媒体中に着色剤を含有してなる、３項ないし６項のいずれか１項に記載された可逆性熱変色記録媒体。
８． 可逆性熱変色記録材料からなる単独色もしくは複数色の可逆性熱変色記録層が、支持体上に所定の文字や図形もしくはパターン状に形成されてなる、３項ないし７項のいずれか１項に記載された可逆性熱変色記録媒体。
９． 可逆性熱変色記録材料からなる単独色もしくは複数色の可逆性熱変色記録層が、予め所定の文字や図形もしくはパターンを形成した支持体上の全部または一部分に積層して形成されてなる、３項ないし７項のいずれか１項に記載された可逆性熱変色記録媒体。」
である。
【０００９】
本発明の可逆性熱変色記録材料は、ヒステリシス性を有しているところに大きな特徴がある。
本発明の記録材料は初期無色の状態から加熱されると無色の状態で昇温し、発色温度域に到達すると発色する。そして温度を下げると発色状態のまま冷却され、初期無色の状態であった例えば室温に到達しても発色状態が保持され直ちに消色することはない。消色するには消色温度まで加熱して最初の発色経路に戻す必要がある。すなわち発色状態になったものを消色状態にするためには発色温度よりも低温側にある消色温度域に加熱して冷却することにより初期消色状態とすることができる。
つまり無色から発色にいたる経路と、発色から無色にいたる経路が異なっており、ヒステリシス性を有している。
このようなヒステリシス性があるので発色した記録を保存することが出来るのである。
勿論化合物と組成により消色温度と発色温度および変色経路における発色開始温度と発色飽和温度の温度巾等に差異はあるが、本発明の記録材料は全てヒステリシス性を有するところに特徴があり、明瞭な記録を得ることができる。
【００１０】
本発明に用いる電子供与性呈色性化合物は感圧・感熱色素として用いられる無色または淡色の色素であり、トリフェニルメタンフタリド系色素、フルオラン系色素、インドリルフタリド系色素、スピロピラン系色素、ローダミンラクタム系色素、トリフェニルメタン系色索、アザフタリド系色素とアゾメチン系色素等がある。以下に具体的なものを例示するが、発消色制御ポリマーと常に相溶しているものであればよく、これらに限定されるものではない。
３−ジエチルアミノ−６−メチル−７−フェニルアミノフルオラン、３−ジエチルアミノ−７−（２−クロロフェニル）アミノフルオラン、３−ジエチルアミノ−７−（２−ブロモフェニル）アミノフルオラン、３−ジエチルアミノ−６−メチル−７−クロロフルオラン、３−ジエチルアミノ−６−メチル−７−（３−トリフルオロメチルフェニル）アミノフルオラン、３−ジエチルアミノ−７−クロロフルオラン、３−ジエチルアミノ−７−ブロモフルオラン、３−ジエチルアミノ−７−ピペリジノフルオラン、３−ジエチルアミノ−７−（Ｎ−エチル−Ｎ−フェニル）アミノフルオラン、３−ジエチルアミノ−７，８−ベンゾフルオラン、３−ジエチルアミノ−６−クロロ−７−（２，３−ジシクロヘキシルフェニル）アミノフルオラン、３−ジエチルアミノ−６−クロロ−７−フェニルアミノフルオラン、３−ジエチルアミノ−６−メチル−７−（２，４−ジメチルフェニル）アミノフルオラン、３−ジエチルアミノ−６−クロロ−７−（３−トリフルオロメチルフェニル）アミノフルオラン、３−ジエチルアミノ−６−メチル−７−フェニルアミノフルオラン、３−ジエチルアミノ−７−（３−トリフルオロメチルフェニル）アミノフルオラン、３−ジプロピルアミノ−７−クロロフルオラン、３−ジエチルアミノ−６−メチル−７−（３−トリクロロメチルフェニル）アミノフルオラン、３−ジエチルアミノ−７−（２−メトキシカルボニルフェニル）アミノフルオラン、３−ジアリルアミノ−７，８−べンゾフルオラン、３−ジエチルアミノ−５−クロロ−７−（Ｎ−α−フェニルエチル）アミノフルオラン、３−ジエチルアミノ−５−メチル−７−（Ｎ−フェニルエチル）アミノフルオラン、３−ジエチルアミノ−５−メチル−７−ジベンジルアミノフルオラン、３−ジエチルアミノ−７−メドキシフルオラン、３−ジエチルアミノ−６−ジエチルアミノフルオラン、３−ジエチルアミノ−７−（ｐ−トルイジノ）フルオラン、３−ジエチルアミノ−５−クロロ−７−｛Ｎ−ベンジル−Ｎ−（トリフルオロメチルフェニル）｝アミノフルオラン、３−ジブチルアミノ−７−（２−クロロフェニル）アミノフルオラン、３−ジエチルアミノ−７−アセトアミノフルオラン、３−ジブチルアミノ−６−クロロ−７−エトキシエチルアミノフルオラン、３−ジブチルアミノ−７−（２−フルオロフェニル）アミノフルオラン、３−ジブチルアミノ−７，８−ベンゾフルオラン、３−シクロヘキシルアミノ−６−クロロフルオラン、３−ジブチルアミノ−６−メチル−７−フェニルアミノフルオラン、３−ジメチルアミノ−５，７−ジメチルフルオラン、３−シクロヘキシルアミノ−６−クロロフルオラン、３−シクロヘキシルアミノ−６−ブロモフルオラン、３−シクロヘキシルアミノ−６−クロロ−７−（２−クロロフェニル）アミノフルオラン、３−（Ｎ−メチル−Ｎ−シクロヘキシル）アミノ−７，８−ベンゾフルオラン、３−（Ｎ−エチル−Ｎ−ｎ−オクチル）アミノ−７，８−ベンゾフルオラン、３−（Ｎ−エチル−Ｎ−ｉ−アミル）アミノ−７，８−ベンゾフルオラン、３−（Ｎ−エチル−Ｎ−ｉ−アミル）アミノ−７−クロロフルオラン、３−（Ｎ−メチル−Ｎ−シクロヘキシル）アミノ−６−メチル−７−（３−トリフルオロメチルフェニル）アミノフルオラン、３−（Ｎ−メチル−Ｎ−ｉ−プロピル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−ベンジル−Ｎ−シクロヘキシル）アミノ−５，６−ベンゾ−７−（４−ブロモナフチル）アミノフルオラン、３−（Ｎ−ｉ−ブチル−Ｎ−メチル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−エチル−Ｎ−ｉ−アミル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−エチル−Ｎ−ヘキシル）アミノ−７−フェニルアミノフルオラン、３−（Ｎ−ｎ−アミル−Ｎ−メチル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−メチル−Ｎ−シクロヘキシル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−メチル−Ｎ−ｎ−プロピル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−ｎ−プロピル−Ｎ−ｉ−プロピル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−エチル−Ｎ−Ｓｅｃ−ブチル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−エチル−Ｎ−ｎ−アミル）アミノ−６−メチル−７−フェニルメチルフルオラン、３−ジ−ｎ−オクチルアミノ−７−（４−クロロフェニル）アミノフルオラン、３−ｎ−オクチルアミノ−７−（４−クロロフェニル）アミノフルオラン、３−（Ｎ−ｎ−ブチル−Ｎ−ｎ−アミル）アミノ−７−（４−アセチル−フェニル）アミノフルオラン、３−ｎ−オクチルアミノ−７−（４−クロロフェニル）アミノフルオラン、３−ｎ−セチルアミノ−７−（４−クロロフェニル）アミノフルオラン、３−ピロリジノ−６−メチル−７−フェニルアミノフルオラン、３−ピロリジノ−７−｛ビス（４−クロロフェニル）メチル｝アミノフルオラン、３−モルホリノ−７−｛Ｎ−プロピル−Ｎ−（４−トリフルオロメチルフェニル）｝アミノフルオラン、３−ピロリジノ−６−クロロ−７−フェニルアミノフルオラン、３−ピロリジノ−６−メチル−７−（３−トリフルオロメチルフェニル）アミノフルオラン、３−モルホリノ−７−｛Ｎ−プロピル−Ｎ−（３−トリフルオロフェニル）｝アミノフルオラン、３−（Ｎ−エチル−Ｎ−エトキシエチル）アミノ−７，８−ベンゾフルオラン、３−｛Ｎ−エチル−Ｎ−（２−エトキシプロピル）｝アミノ−６−メチル−７−フェニルアミノフルオラン、３−（Ｎ−エチル−Ｎ−テトラヒドロフルフリル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−
（Ｎ−メチル−Ｎ−フェニル）アミノ−７−アミノフルオラン、３−（Ｎ−メチル−Ｎ−フェニル）アミノ−７−Ｎ−メチルアミノフルオラン、３−（Ｎ−メチル−Ｎ−フェニル）アミノ−７−ジメチルアミノフルオラン、３−（Ｎ−メチル−Ｎ−フェニル）アミノ−７−ジプロピルアミノフルオラン、３−（Ｎ−エチル−Ｎ−フェニル）−６−メチル−７−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノフルオラン、３−（Ｎ−エチル−Ｎ−フェニル）アミノ−７−ジメチルアミノフルオラン、３−（Ｎ−エチル−Ｎ−フェニル）アミノ−７−ジプロピルアミノフルオラン、３−（Ｎ−エチル−Ｎ−フェニル）アミノ−７−アミノフルオラン、３−（Ｎ−フェニル−Ｎ−プロピル）アミノ−７−アミノフルオラン、３−（Ｎ−エチル−Ｎ−フェニル）アミノ−７−Ｎ−メチルアミノフルオラン、３−（Ｎ−プロピル−Ｎ−フェニル）アミノ−７−Ｎ−メチルアミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−５−メトキシ−７−ジベンジルアミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−６−ｔ−ブチル−７−（４−メチルフェニル）アミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−７−（２−メトキシベンゾイル）アミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−７−アセチルアミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−７−ジベンジルアミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−７−ジエチルアミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−７−エチルアミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−メチルフェニル）｝アミノ−７−アミノフルオラン、３−（Ｎ−メチル−Ｎ−フェニル）アミノ−６−メチル−７−フェニルアミノフルオラン、３−（３−トリフルオロメチルフェニル）アミノ−６−ジエチルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−６−メチル−７−フェニルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−（Ｎ−メチル−Ｎ−フェニル）アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−（α−フェニルエチル）アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−ブチルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−ジベンジルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−｛ビスー（４−メチルベンジル）｝アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−ベンゾイルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−５−メチル−７−ジベンジルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−５−クロロ−７−ジベンジルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−６−メチルフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−５−メトキシフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７，８−ベンゾフルオラン、３−｛Ｎ−プロピル−Ｎ−（４−メチルフェニル）｝アミノ−６−メチル−７−｛Ｎ−エメル−Ｎ−（４−メチルフェニル）｝アミノフルオラン、３−｛Ｎ−プロピル−Ｎ−（４−メチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−エチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−エチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−メチルフェニル）｝アミノ−７−ジエチルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−エチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−プロピル−Ｎ−（４−エチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−メチル−Ｎ−（２，４−ジメチルフェニル）｝アミノ−７−ベンジルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（２，４−ジメチルフェニル）｝−７−アミノフルオラン、３−｛Ｎ−メチル−Ｎ−（２，４−ジメチルフェニル）｝アミノ−７−メチルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（２，４−ジメチルフェニル）｝アミノ−７−エチルアミノフルオラン、３−｛Ｎ−エチル−Ｎ−（２，４−ジメチルフェニル）｝アミノ−７−ベンジルアミノフルオラン、３−｛Ｎ−プロピル−Ｎ−（２，４−ジメチルフェニル）｝アミノ−７−アミノフルオラン、３−｛Ｎ−メチル−Ｎ−（４−クロロフェニル）｝アミノ−アミノフルオラン、３−｛Ｎ−エチル−Ｎ−（４−クロロフェニル）｝アミノ−７−アミノフルオラン、３−
｛Ｎ−プロピル−Ｎ−（４−クロロフェニル）｝アミノ−７−アミノフルオラン、３−シクロヘキシルアミノ−７−ブロモアミノフルオラン、２，７−ジクロロ−３−ｎ−ブチルアミノ−６−メチルフルオラン、３−ジ−ｎ−ブチルアミノ−６，７−ブチレンフルオラン、３−アミノ−５−メチルフルオラン、２−メチル−３−アミノ−６−メチル−７−メチルフルオラン、
１，３，３−トリメチルインドリノ−６′−ニトロベンゾピリロスピラン、１，３，３−トリメチルインドリノ−６′−ニトロ−８′−メトキシベンゾピリロスピラン、１，３，３−トリメチルインドリノ−６′−ブロモベンゾピリロスピラン、１，３，３−トリメチルインドリノ−８′−メトキシベンゾピリロスピラン、１，３，３−トリメチルインドリノ−ベンゾピリロスピラン、１，３，３−トリメチルインドリノーβ−ナフトピリロスピラン、
トリス（４−ジメチルアミノフェニル）メタン−２−カルボキシレート（ＣＶＬ）、ビス（４−ジメチルアミノフェニル）フェニルメタン−２−カルボキシレート（ＭＧＬ）、ビス（４−ジメチルアミノフェニル）−（４−クロロ）フェニルメタン−２−カルボキシレート、ビス（４−ジメチルアミノフェニル）−（４−ジエチルアミノ）フェニルメタン−２−カルボキシレート、ビス（４−ジブチルアミノフェニル）フェニルメタン−２−カルボキシレート、｛２−ヒドロキシ−（４−ジエチルアミノ）フェニル｝−（２−メトキシ−５−メチルフェニル）フェニルメタン−２−カルボキシレート、｛２−ヒドロキシ−（４−ジメトキシアミノ）フェニル｝−（２−ヒドロキシ−５−クロロフェニル）フェニルメタン−２−カルボキシレート、（４−ジメチルアミノフェニル）−（２−ヒドロキシ−４−クロロ−５−メトキシフェニル）フェニルメタン−２−カルボキシレート、３−｛２−エトキシ−（４−ジエチルアミノ）フェニル｝−３−（２−メチル−１−エチルインドール−３−イル）−４−アザフタリド、３−｛２−エトキシ−（４−ジエチルアミノ）フェニル｝−３−（２−メチル−１−ｎ−オクチルインドール−３−イル）−４−アザフタリド、３，３−ビス（２−メチル−１−エチルインドール−３−イル）フタリド、３−｛２−メトキシ−（４−ジエチルアミノ）フェニル｝−３−（２−メチル−１−エチルインドール−３−イル）−フタリド、３−｛２−メチル−（４−ジエチルアミノ）フェニル｝−３−（１，２−ジメチルインドール−３−イル）−フタリド、３，３−ビス（２−メチル−１−オクチルインドール−３−イル）フタリド、ローダミンアニリノラクタム、ローダミン−２−クロロアニリノラクタム、ローダミン−４−クロロアニリノラクタム、ビス｛２−メチル−（４−ジメチルアミノ）フェニル｝−｛（２，５−ジメチルアミノ）フェニル｝メタン。
【００１１】
本発明に用いる電子受容性フェノール化合物の好ましい例としては、融点が７０℃以上のものである。融点が７０℃以下の電子受容性フェノール化合物とガラス転移温度が６０℃付近の発消色制御ポリマーを用いた場合、消色温度域に加熱されたときに電子受容性フェノール化合物の融解が起こり始め、結果として消色が起こりにくくなる傾向が見られる。このため、７０℃以上の電子受容性フェノール化合物を用いるのが好ましい。電子受容性フェノール化合物の具体例を示すと、没食子酸のエステルが好ましく、より具体的には、
没食子酸ｎ−プロピル、
没食子酸ｎ−ブチル、
没食子酸ｉ−アミル、
没食子酸ラウリル、
没食子酸セチル、
没食子酸ミリスチル、
没食子酸ステアリル、
没食子酸ベヘニル等が挙げられる。しかし、これらに限定されることはない。
本発明に用いる発消色制御ポリマーは、発消色制御の点から、電子供与性呈色性化合物と常に相溶し、かつ、前記電子受容性フェノール化合物と、相溶、非相溶の変化を起こすことができるポリマーである必要がある。さらに、該ポリマーは、電子受容性フェノール化合物との関係において、そのガラス転移温度が発消色に関与する。発消色制御ポリマーのガラス転移温度が高いと、消色が起こりにくくなり、低いと消色のコントロールがしやすくなる。この結果から、発消色制御ポリマーのガラス転移温度は６０℃以下が好適である。すなわち、６０℃を越えるガラス転移温度であると消色時における電子受容性フェノール化合物との非相溶の状態がとりにくくなる。すなわち、発消色制御ポリマーが硬い状態であるため相分離を起こしにくくなり、消色しにくくなるか、消色に時間がかかる。発色に関しては、発消色制御ポリマーのガラス転移温度の影響を比較的受けないが、ガラス転移温度が６０℃を越えると発色のレスポンスとコントラストが悪くなる傾向がある。このことから６０℃以下のガラス転移温度を持つポリマーを用いることが好ましい。
【００１２】
また、本発明に用いる発消色制御ポリマーは電子受容性フェノール化合物と特定条件で明確に相溶、非相溶する点、つまり良好な発消色の制御の点から、スチレン系ポリマーとジエン系ポリマーが好ましい。以上より、本発明に用いる発消色制御ポリマーを例示すると、スチレン系ポリマーとジエン系ポリマーが好ましく、具体的には、スチレン−ブタジエンコポリマー、スチレン−イソプレン−スチレンコポリマー、スチレン−アクリルエステルコポリマー、ブタジエンポリマー、スチレン−エチレン−ブタジエン−スチレンコポリマー等が挙げられる。
【００１３】
本発明における発消色制御ポリマー：電子受容性フェノール化合物：電子供与性呈色性化合物の配合比は重量比で、１：０．１〜０．６：０．０１〜０．０９が好ましい。電子受容性フェノール化合物の割合がこれを越えると発消色に必要な相溶、非相溶をとらせるコントロールが難しくなり、加熱発色状態の記録材料を冷却しても、発色状態を保持できなくなる傾向がみられる。即ち、発消色制御ポリマー、電子受容性フェノール化合物及び電子供与性呈色性化合物の３成分が完全に相溶できず、非相溶部分の電子受容性フェノール化合物の影響で、大部分が非相溶となり、その結果、冷却時の発色濃度が下がってしまうため好ましくない。また、割合がこれを下回ると実用上十分な発色濃度が得られず、結果としてコントラストが落ち、記録材料として用いるのに不適となるため好ましくない。また、電子供与性呈色性化合物の割合がこれを越えると、電子供与性呈色性化合物によっては、常に相溶状態をとることができないものも出てくる恐れがあり、その結果電子受容性フェノール化合物が発消色制御ポリマーとの間で、相溶、非相溶の変化を起こしても、常に電子供与性呈色性化合物と反応できるため、消色が起こり難くなり、消色時のベース濃度が高くなるため、結果としてコントラストが悪くなるため好ましくない。逆にこれを下回ると、電子受容性フェノール化合物の割合が少なくなった場合と同様に十分な発色濃度が得られないので好ましくない。また、前記電子受容性フェノール化合物：電子供与性呈色性化合物の配合比は重量比で１：０．１〜０．９の範囲であることが特に好ましい。電子受容性フェノール化合物の割合が多くなると、冷却時の発色濃度が低くなる傾向がみられ、また、電子受容性フェノール化合物の割合が少なくなると、発色濃度が得られなかったり、コントラストが悪くなる傾向があるため好ましくない。
これらの配合比について検討した結果から、それぞれの関係は、以下の通りである。即ち、発消色制御ポリマーおよび電子受容性フェノール化合物の配合比は、発色濃度と、消色速度に影響する。発消色制御ポリマーおよび電子供与性呈色性化合物の配合比は、発色濃度とベース濃度に影響する。電子受容性フェノール化合物および電子供与性呈色性化合物の配合比は、発色濃度と、コントラストに影響することが明らかとなった。従って、前記のように配合比の限定なしには、実用性のある記録材料は得られず、配合比を限定することは、所望の記録材料を作成する上で必要である。本発明における発消色の機構は、特に、発消色制御ポリマーと、電子受容性フェノール化合物の相溶と非相溶から起こっているため、発消色制御ポリマーおよび電子受容性フェノール化合物の配合比の限定が重要である。
【００１４】
本発明の可逆性熱変色記録媒体は前記記録材料を支持体上に層状に配置してなり、支持体としては、透明、半透明または不透明なポリマーフイルムあるいはシート、合成紙および加工紙、ガラス板、金属板等が用いられ、支持体上に直接記録層を設けるか、支持体上に支持体と記録層の密着性を向上させるため一旦アンダーコート層を施し、その上に記録層を設けてもよい。このようなアンダーコート層は密着性の向上の他、断熱性等を付与する効果もある。また、記録媒体の表面とサーマルヘッドとの融着防止、記録層の耐擦過性の向上、記録層の酸化防止、有害気体等による記録層の汚染防止のために、記録媒体の表面に透明な保護層を設けてもよい。前記保護層は無機物の蒸着やポリマー溶液等のコーティングにより形成するか、あるいはポリマーフイルムの積層によって形成することができる。ポリマーフイルムを積層するために、記録層との間に粘着層あるいは接着層を設けてもよい。
【００１５】
本発明の可逆性熱変色記録材料を用いる可逆性熱変色記録媒体は、着色剤を記録層中または、記録層以外の層、例えば、支持体、アンダーコート層、保護層、接着または粘着層の中に存在させ、着色剤の色と、着色剤と発色状態の電子供与性呈色性化合物の混ざった色との有色から有色への変化を行わせることができる。ここで用いることのできる着色剤の種類および添加量は、記録層中に存在させる場合には、電子受容性フェノール化合物と電子供与性呈色性化合物の発色反応を阻害せず、かつ、発消色制御ポリマーと電子受容性フェノール化合物の相溶と非相溶の変化を阻害しないものである必要があり、そのような要件を満たすものであれば使用できる。また、記録層以外に存在する場合も含めると、著しいコントラストの低下を起こすような添加は好ましくない。同様に、記録材料保護のため、紫外線吸収剤等の添加剤を加えてもよい。
本発明の可逆性熱変色記録材料を支持体上に所定の文字、図形もしくはパターン状に形成して可逆性熱変色記録媒体として用いることができる。即ち、該記録層が、発色温度域に加熱されることにより、記録層の一部もしくは全部が発色または変色し、記録または表示が可能となる。この時、記録層は、単独色の発色の他に、異なる色に発色する可逆性熱変色記録材料を、ストライプ状、マトリックス状など種々な模様に塗り分けて形成すれば、複数色の発色が可能となる。
さらに、本発明の可逆性熱変色記録材料は、発色状態が下地を隠蔽する能力を有する。したがって、支持体上に、予め所定の文字、図形もしくはパターンを形成し、その上に前記記録層を積層した形で用いることもできる。該記録層を、発色温度域または、消色温度域に加熱することで、該記録層の一部または全部が、発色または消色または変色し、支持体上の文字、図形もしくはパターンの一部または全部が、隠蔽または透視されて可逆的な記録または表示が可能となる。また、記録層と支持体の両方に、所定の文字、図形、パターンを形成し、組み合わせて用いることもできる。
また、本発明でいう記録材料は表示材料も包含した用語である。
【００１６】
【発明の実施の形態】
次に本発明がどのように実施されるのか実施の形態を作用とともに説明する。
本発明の可逆性熱変色記録材料は、発消色制御ポリマー：電子受容性フェノール化合物：電子供与性呈色性化合物を重量比で１：０．１〜０．６：０．０１〜０．０９の割合で揮発性有機溶媒に溶解して混合溶液とすることにより製造することができる。またエマルジョン重合して形成した発消色制御ポリマーエマルジョンに電子受容性フェノール化合物と電子供与性呈色性化合物を分散して製造することもできる。この混合液を支持体に塗布、乾燥すれば可逆性熱変色記録媒体を製造することができる。
【００１７】
本発明の可逆性熱変色記録材料は、発色状態を維持する時間を任意に制御することができる。すなわち、発色状態を１ヶ月以上の長期間維持することもできれば数十分で消色させることもできる。発色状態の維持時間の制御は電子受容性フェノール化合物と発消色制御ポリマーの組み合わせ及び、その配合比を選択することにより可能となる。
例えば、没食子酸エステル（ｎ−プロピル、ｎ−ブチル、ｉ−アミル、ステアリル、セチル、ラウリル等のエステル）とスチレン−ブタジエンコポリマーまたはスチレン−（メタ）アクリルエステルコポリマーを組み合わせて用いたときには、発色した可逆性熱変色記録材料は室温において１ヶ月以上に亘り発色状態を維持することが可能である。また、没食子酸エステルとスチレン−イソプレン−スチレンコポリマーを組み合わせて用いたときには、発色した可逆性熱変色記録材料は室温放置数十分で消色状態にすることができる。
【００１８】
本発明の可逆性熱変色記録材料は、支持体上に層状に配置した記録媒体として使用することができるので、混合液を溶液として形成する場合使用する有機溶媒は発消色反応に関与しない溶剤が好適であり、もし反応に関与する溶剤を使用する場合は発色反応時には系から揮発して除去されるものである必要がある。
支持体に設ける記録材層は乾燥膜で膜厚１μｍ〜３０μｍが好ましく、２μｍ〜６μｍがより好ましい。
本発明の記録媒体は熱転写プリンター等により発色させて記録を表示することができ、また消色温度の熱風を吹きつけること等により消色することが出来る。
【００１９】
つぎに本発明の作用の面から実施形態を説明する。本発明可逆性熱変色記録材料はヒステリシスを示し、室温で消色状態の組成物を加熱して発色させて室温まで冷却しても消色しない。
電子供与性呈色性化合物、電子受容性フェノール化合物と発消色制御ポリマーの有機溶媒溶液から有機溶媒を蒸発除去して得られた本発明の熱記録材料の発色と消色の現象を図１に示す。図１において、消色状態Ａのものを加熱し、ＢとＣを経てＤ（Ｄ付近またはそれ以上の温度を発色温度域という）に到達すると、熱記録材料中の電子供与性呈色性化合物、電子受容性フェノール化合物と発消色制御ポリマーは相溶状態となって発色し、これを室温まで冷却したとき消色状態Ａから発色状態Ｄに至る経路とは異なる経路であるＤからＥを辿り、発色状態が維持される。次にＥ状態の熱記録材料をＢとＣの間の温度（この近傍の温度領域を消色温度域という）に加熱しＥ状態からＢ、Ｃ状態となると、電子受容性フェノール化合物は発消色制御ポリマーと非相溶状態となって、反応し発色状態であった電子供与性呈色性化合物との結合が切れて熱記録材料は消色状態となる。これを室温に冷却したときＥ状態に戻らずＡ状態となり消色状態は維持されており、経時的にも安定である。
このように反応が異なる経路を通って可逆となるヒステリシスを示すところに大きな特徴がある。
この現象を電子供与性呈色性化合物としてクリスタルバイオレットラクトン
（以下ＣＶＬ）、電子受容性フェノール化合物として没食子酸ステアリルと発消色制御ポリマーとしてスチレン−ブタジエンコポリマーの均質溶液から溶剤を蒸発除去して作製した本発明の一例の可逆性熱変色記録材料［Ｘ］、ＣＶＬとスチレン−ブタジエンコポリマーの均質溶液から溶剤を蒸発除去した材料［Ｙ］、没食子酸ステアリルとスチレン−ブタジエンコポリマーの均質溶液から溶剤を蒸発除去して作製した材料［Ｚ］の各々について示差走査熱分析（以下ＤＳＣ）により、熱的に解析した資料に基づいてさらに詳しく説明する。ＤＳＣ測定は、セイコー電子工業株式会社製ＤＳＣ−ＳＳＣ５８０型を用い、昇温速度５℃／分にて行った。
【００２０】
図２ラインａは、前記熱記録材料［Ｘ］を発色温度域である１２０℃に加熱した後に室温まで冷却し、発色状態にある試料を用いて、図２ラインｂは、前記熱記録材料［Ｘ］を消色温度域である６０℃に加熱した後に室温まで冷却し、消色状態にある試料を用いて夫々ＤＳＣ測定をおこなった結果である。吸熱ピーク２−１と吸熱ピーク２−１１は、ポリマーの非晶状態への変化に伴うものであり、吸熱ピーク２−２、２−３と２−４は、エネルギー的に若干差異のある発色状態が混在している熱記録材料に伴うものであり、吸熱ピーク２−１２、２−１４も同じ状態のエネルギー的に若干差異のある発色状態が混在している熱記録材料に伴うものである。吸熱ピーク２−１５は、昇温過程で未だＣＶＬとの反応に関与していない没食子酸ステアリルの融解に伴うものである。すなわち、図２ラインｂの吸熱ピーク２−１５は、消色状態において、没食子酸ステアリルが非相溶状態となって分離独立して存在することを示している。一方、図２ラインａでは、２−１５に相当する吸熱ピークが存在していない。非相溶状態の没食子酸ステアリルが試料中に存在すれば、融点近傍の１００℃付近に２−１５に相当する吸熱ピークが発生するものと思われるが、その点に吸熱ピークが存在しないことは、測定に供した発色状態の試料［Ｘ］は、ＣＶＬ、没食子酸ステアリルとスチレン−ブタジエンコポリマーの３成分が相溶状態となっていることを示している。
【００２１】
図３に材料［Ｙ］を消色温度域の６０℃まで加熱した後、室温まで冷却した試料のＤＳＣ測定を行った結果を、図４には材料［Ｙ］を発色温度域の１２０℃まで加熱した後、室温まで冷却したＤＳＣ測定の結果をそれぞれ示した。図３と図４に見られる吸熱ピーク３−１と４−１は、ポリマーが非晶状態になるときの吸熱であり、両者にほとんど差が見られないことから、発色状態または消色状態のいずれの状態でも発消色制御ポリマーに電子供与性呈色性化合物が均質に溶解していることを示唆するものである。
【００２２】
図５は材料［Ｚ］を消色温度域の７０℃まで加熱した後、室温に冷却した試料を用いＤＳＣ測定を行った結果を示したものである。吸熱ピーク５−１は発消色制御ポリマーが非晶状態になることによるものであり、図２および図３、図４に比較してブロードな吸熱ピークとなっており、広い温度範囲の吸熱が起きているのは電子受容性フェノール化合物の影響によるもの、すなわち、非相溶状態で存在するためである。また、吸熱ピーク５−２は非相溶状態で存在する電子受容性フェノール化合物が溶解することに伴うものである。なお、吸熱ピークが現れる温度は、共存する物質の影響を受けて、若干ずれることがある。
【００２３】
以上のＤＳＣ測定の結果を総合すれば、発消色制御ポリマーと電子供与性呈色性化合物の混合物は、室温〜消色温度域〜発色温度域に亘って常に相溶状態である。したがって、本発明においても、発消色制御ポリマーに常に相溶状態をとれる電子供与性呈色性化合物を選択しなければならず、好ましい組み合わせとすることが必要となる。また、電子受容性フェノール化合物は発色温度域で溶解し、発消色制御ポリマーと相溶することにより、常に相溶状態である上記呈色性化合物と反応して発色する。このものを室温に冷却すると、相溶状態が保持されたままとなり、発色した状態が維持できる。反応に関与している電子受容性フェノール化合物は室温から消色温度域に加熱されたときに発消色制御ポリマーと非相溶の状態となり、前記呈色性化合物との結合が切れて消色する。これを室温に戻したときにも非相溶の状態が維持されるため、安定な消色を保つことができる。
【００２４】
次に、消色状態において、電子受容性フェノール化合物と発消色制御ポリマーとの結晶状態を明らかにするためＸ線回折測定を行った。
前記可逆性熱変色記録材料［Ｘ］の消色状態におけるＸ線回折測定結果を図６に示した。スチレン−ブタジエンコポリマーのＸ線回折測定を図７に、没食子酸ステアリルのＸ線回折測定結果を図８に示した。
図８において、没食子酸ステアリルは２θ／ｄｅｇ．２〜２５に結晶化ピークが幾つか認められ、特に２θ／ｄｅｇ．２〜７の間に大きな結晶化ピークが存在する。図７において、スチレン−ブタジエンコポリマーは２θ／ｄｅｇ．２３付近に比較的小さい結晶化ピーク７−２が認められる。
一方、図６において、可逆性熱変色記録材料［Ｘ］の消色状態のものは、６−１と６−２として示す小さいピークであるが、６−２はスチレン−ブタジエンコポリマーの結晶化に基づくものである。６−１は没食子酸ステアリルに基づく物であり、没食子酸ステアリルは殆ど結晶化していないと推定できる。
以上に述べたように本発明は、発消色制御ポリマー、電子受容性フェノール化合物、電子供与性呈色性化合物の関係、特に発消色制御ポリマーと電子受容性フェノール化合物との相溶、非相溶の可逆的変化によって発色と消色が可逆的に行われる。電子受容性フェノール化合物のポリマーとの非相溶の状態は、該フェノール化合物が結晶状態であっても非晶状態であってもよく、特定の状態でポリマーから分離することにとらわれることはない。すなわち、図２−ａにおいて該フェノール化合物の結晶化による発熱ピークが観察されない。また、図６のＸ線回折の測定結果から該フェノール化合物の明確な結晶化のピークが認められないことから、該フェノール化合物の長鎖アルキル基の凝集結晶化による消色とは異なることは明らかである。
【００２５】
【実施例】
以下に実施例を挙げて説明する。
【００２６】
実施例１
スチレン−ブタジエンコポリマー ２０重量部
（商品名 「アスマー」、旭化成工業株式会社製、Ｔｇ＝−６０℃）
没食子酸ステアリル １０重量部
クリスタルバイオレットラクトン（以下ＣＶＬ） １重量部
上記組成物を１７０重量部のテトラヒドロフラン（以下ＴＨＦ）に溶解し、可逆性熱変色記録材料の溶液を作製した。この溶液を１１０μｍの厚さのポリプロピレン製合成紙（商品名 「ユポＦＢＤ＃１１０」、王子油化株式会社製）にワイヤーバーを用いて塗布した後、１００℃に加熱乾燥することにより、青紫色に発色した厚さ４μｍの可逆性熱変色記録材料からなる記録層を設け、記録媒体を作製した。この記録媒体を６０℃に加熱し、室温（２０℃）まで冷却したところ、青紫色の発色が消え、ベースの合成紙の発色状態に近い白色となった。この媒体を１２０℃へ加熱後、室温まで冷却し、その後、６０℃へ加熱後、室温まで冷却する操作を繰り返したところ、発色と消色を可逆的に行うことができた。この時の発色状態と消色状態の光学濃度をマクベス濃度計ＲＤ−９１５を用いて測定したところ、発色状態で１．５２、消色状態で０．１４のＯＤ値を示し、優れた記録媒体が得られた。以下、ＯＤ値測定は、同機を用いた。
【００２７】
実施例２
スチレン−ブタジエンコポリマー ２０重量部
没食子酸ステアリル １０重量部
ＣＶＬ １重量部
上記組成物をメチルエチルケトン（略名ＭＥＫ）とトルエン１：１の混合溶媒１７０重量部に溶解し、可逆性熱変色記録材料の溶液を作製した。この溶液を１１０μｍの厚さのポリプロピレン製合成紙にワイヤーバーを用いて塗布した。これを１２０℃に加熱乾燥することにより、青紫色に発色した厚さ４μｍの可逆性熱変色記録材料からなる記録層を設けた。前記の記録層上に５％メチルセルロース（商品名 「メトローズＳＭ−２５」、信越化学工業株式会社製）水溶液をワイヤーバーを用いて塗布した後、加熱乾燥して厚さ２μｍの中間層を形成した。この中間層の上にＵＶ硬化型エポキシ樹脂（商品名 「アデカオプトマーＫＲ５１０）」、旭電化工業株式会社製）をワイヤーバーを用いて塗布した後、４００Ｗ水銀灯を用いて厚さ２μｍの硬化皮膜を形成し、保護層付き記録媒体を作製した。この記録媒体を熱転写プリンタ（商品名 「ＰＣ−ＰＲ１５０ｎ」、日本電気株式会社製）を用いて画像を形成し、その後、この記録媒体を６５℃に設定したゴム製ヒートロールの間を通過させて画像を消去した。その時の発色状態と消色状態の光学濃度を測定したところ、ＯＤ値は発色状態で１．５０、消色状態で０．１６であった。また、上記条件と同様な発色・消色の操作を繰り返し３０サイクル実施したが、プリンタのサーマルヘッドと記録媒体の保護層表面が融着することもなく、またＯＤ値にも大きな変化は生じなかった。
【００２８】
実施例３
１００μｍの厚さのポリエチレンテレフタレート（ＰＥＴシート）に５％メチルセルロース水溶液をワイヤーバーを用いて塗布、加熱乾燥して厚さ２μｍのアンダーコート層を形成した。次に、
スチレン−ブタジエンコポリマー ２０重量部
没食子酸ステアリル １０重量部
ＣＶＬ １重量部
上記組成物をＭＥＫとトルエン１：１の混合溶媒１７０重量部に溶解し、可逆性熱変色記録材料の溶液（Ａ溶液）を作製した。次に、
スチレン−ブタジエンコポリマー ２０重量部
没食子酸ステアリル １０重量部
ローダミンＢラクタム １重量部
をＭＥＫとトルエン１：１の混合溶媒１７０重量部に溶解し、可逆性熱変色記録材料の溶液（Ｂ溶液）を作製し。
前記アンダーコート層を設けたＰＥＴシート上に、グラビア版を用い８ｍｍ幅のストライプとなるようにＡ溶液とＢ溶液を塗り分け、加熱乾燥して、厚さ４μｍの可逆性熱変色記録材料よりなるストライプ模様状に青紫色および赤色に発色可能な記録層を設けた記録媒体を作製した。
前記の記録媒体上に、５％メチルセルロース水溶液をワイヤーバーを用いて塗布、乾燥して厚さ２μｍの中間層を形成し、さらに前記中間層の上にＵＶ硬化型エポキシ樹脂をワイヤーバーを用いて塗布した後、４００Ｗ水銀灯を用いて厚さ２μｍの硬化皮膜を形成し、保護層付き記録媒体を作製した。
前記熱転写プリンタを用いて、記録媒体を２色発色させることができた。また、８０℃程度のドライヤーの熱風を用いて消色ずることができた。
【００２９】
実施例４〜２１
表１の配合例４〜２１の組成物を各々ＴＨＦ１７０重量部に溶解させ、可逆性熱変色記録材料の溶液を作製し、ポリプロピレン製合成紙にワイヤーバーを用いて塗布した後、加熱乾燥して合成紙上に可逆性熱変色記録材料からなる記録層を形成した。さらに、記録層の上に５％メチルセルロース水溶液をワイヤーバーを用いて塗布した後、加熱乾燥して厚さ２μｍの中間層を形成し、さらに前記中間層の上にＵＶ硬化型エポキシ樹脂をワイヤーバーを用いて塗布した後、４００Ｗ水銀灯を用いて厚さ２μｍの硬化皮膜を形成し、保護層付き記録媒体を作製した。いずれの例においても、前記熱転写プリンタを用いて画像を形成することができた。また、７５℃に設定したゴム製ヒートロールの間を通過させて画像を消去することができた。また、この発色、消色は繰り返して行うことができた。表２に各実施例の発色状態および消色状態の光学濃度測定値を示した。
【００３０】
【表１】

【００３１】
（註）
ＣＶＬ：山田化学株式会社製、クリスタルバイオレットラクトン（青紫）
ＮＣ−ＢＫ：保土ケ谷化学工業株式会社製、フルオラン系ロイコ染料（黒）
ＡＰＴ：山田化学株式会社製、フルオラン系ロイコ染料（緑）
ＯＲ−５５：山田化学株式会社製、フルオラン系ロイコ染料（橙）
ＮＢＰ−１：山本化成株式会社製、アザフタリド系ロイコ染料（青）
ＮＣＹ−２［１］：保土ケ谷化学工業株式会社製、アゾメチン系ロイコ染科
（黄）
ＴＨ−１０７：保土ケ谷化学工業株式会社製、フルオラン系ロイコ染料（黒）
スチレン−ブタジエンコポリマー：商品名「アスマー」、旭化成工業株式会社製、Ｔｇ＝−６０℃
スチレン−アクリルエステルコポリマー：商品名「ハイマーＴＢ−１０００Ｆ」、三洋化成工業株式会社製、Ｔｇ＝５８℃
ブタジエンポリマー：商品名「ＲＢ−８２０」、日本合成ゴム工業株式会社製、Ｔｇ＝−１２℃
スチレン−イソプレン−スチレンコポリマー；商品名「ＳＩＳ−５０００」、日本合成ゴム工業株式会社製、Ｔｇ＝−７０℃
スチレン−エチレン−ブタジエン−スチレンコポリマー：商品名「クレイトンＧ−１６５０」、シェルジャパン株式会社製、Ｔｇ＝−４２℃
塩化ビニル−酢酸ビニルコポリマー：商品名「デンカビニル１０００Ａ」、電気化学工業株式会社製、Ｔｇ＝６５℃
ポリ（ｐ−ビニルフェノール）：商品名「マルカリンカーＭＢ」、丸善石油化学株式会社製、Ｔｇ＝１４７℃
ポリメチルメタクリレート：商品名「ダイヤナールＢＲ−７７」、三菱レイヨン株式会社製、Ｔｇ＝８０℃
【００３２】
【表２】

【００３３】
比較例１〜１０、１３
表３の配合例２３〜３２および表１の配合例２２の組成物を各々ＴＨＦ１７０重量部に溶解し、この溶液を１１０μｍの厚さのポリプロピレン製合成紙にワイヤーバーを用いて塗布した。これを１２０℃に加熱乾燥することによって、厚さ４μｍの記録層を設けた。 前記の記録層に５％メチルセルロース水溶液をワイヤーバーを用いて塗布した後、加熱乾燥して厚さ２μｍの中間層を形成した。この中間層の上に、ＵＶ硬化型エポキシ樹脂をワイヤーバーを用いて塗布した後、４００Ｗ水銀灯を用いて厚さ２μｍの硬化皮膜を形成し、保護層付き記録媒体を作製した。この記録媒体を用いて実施例２と同様にして得られる発色濃度および消色濃度を測定し、表４に示した。
【００３４】
比較例１１
エポキシ樹脂 １８．６重量部
（商品名 「アデカレジンＥＰ−４０００」、旭電化工業株式会社製）
トリエチレンテトラミン １．４重量部
没食子酸ステアリル １０ 重量部
ＣＶＬ １ 重量部
上記組成物をトルエン１８０重量部に溶解し、この溶液を１１０μｍの厚さのポリプロピレン製合成紙にワイヤーバーを用いて塗布した。そして、これを８０℃に加熱乾燥し溶剤除去後、８０℃で２４時間加熱硬化を行い、厚さ４μｍの記録層を設けた。以後、比較例１〜１０と同様な方法で保護層を作製した。この記録媒体を用いて実施例２と同様にして得られる発色濃度および消色濃度を測定し、表４に示した。
【００３５】
比較例１２
ポリオール ６．４重量部
（商品名 「タケラックＵ−２５」７５％酢酸ブチル溶液、武田薬品工業株式会社製）
ポリイソシアネート １３．６重量部
（商品名 「タケネートＤ−１１０Ｎ」７５％酢酸エチル溶液、武田薬品工業株式会社製）
没食子酸ステアリル １０ 重量部
ＣＶＬ １ 重量部
上記組成物をＭＥＫ１４５重量部に溶解し、この溶液を１１０μｍの厚さのポリプロピレン製合成紙にワイヤーバーを用いて塗布した。そして、これを８０℃に加熱乾燥し溶剤除去後、８０℃で２４時間加熱硬化を行い、厚さ４μｍの記録層を設けた。以後、比較例１〜１０と同様な方法で保護層付き記録媒体をを作製した。この記録媒体を用いて実施例２と同様にして得られる発色濃度および消色濃度を測定し、表４に示した。
前記比較例１１、１２で得た記録材料を熱転写プリンタを用いて印字したが発色しなかった。
【００３６】
【表３】

【００３７】
（註） 表中の略号は表１と同じである。
【００３８】
【表４】

【００３９】
前記実施例１１と比較例１、４及び６の比較の結果により、前記発消色制御ポリマー及び、電子受容性フェノール化合物の配合比の臨界点が、適切であることがわかる。また、実施例１、４及び９と比較例２、３、５及び８の比較の結果より、発消色制御ポリマー及び、電子供与性呈色性化合物の配合比の臨界点が適切であることがわかる。比較例１３においては、発消色制御ポリマーのガラス転移温度が６０℃を越えるため、該ポリマーと電子受容性フェノール化合物の消色するための非相溶の変化が起こりにくくなり、消色時の濃度に影響していることがわかる。 また、比較例７及び１０で得た記録媒体は殆ど発色しなかった。比較例８、及び、９で得た記録媒体は発色濃度は十分であったが、消色時の濃度が大きく全く実用に適していなかった。配合比以外で満足しない結果となった理由としては、比較例７においては、長鎖の飽和カルボン酸では、電子供与性呈色性化合物と相溶せず反応できないためであり、比較例１０、１１及び１２においては、発消色制御ポリマーとなるはずであったポリマーの官能基が発色阻害を起こしているためである。比較例９においては、発消色制御ポリマー中の官能基と電子供与性呈色性化合物が常に反応できる状態にあるためである。
【００４０】
【発明の効果】
本発明は発色と消色を繰り返しても材料の劣化がなく使用ずることができる効果が奏せられ、画像のコントラストも良好であり、所望の記録保持ができる利点がある。
【図面の簡単な説明】
【図１】可逆性熱変色記録材料の温度と発色濃度の関係を表わす説明図である。
【図２】発色状態および消色状態の可逆性熱変色記録材利のＤＳＣチャートである。
【図３】６０℃まで加熱した後、室温に冷却したＣＶＬとスチレン−ブタジエンコポリマーの均質材料のＤＳＣチャートである。
【図４】１２０℃まで加熱した後、室温に冷却したＣＶＬとスチレン−ブタジエンコポリマーの均質材料のＤＳＣチャートである。
【図５】７０℃まで加熱した後、室温に冷却した没食子酸ステアリルとスチレン−ブタジエンコポリマーの均質材料のＤＳＣチャートである。
【図６】可逆性熱変色記録材料の消色状態におけるＸ線回折チャートである。
【図７】没食子酸ステアリルのＸ線回折チャートである。
【図８】スチレン−ブタジエンコポリマーのＸ線回折チャートである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reversible thermochromic recording material and a reversible thermochromic recording medium. More specifically, a reversible thermochromic recording material comprising at least a color development / erasing control polymer, an electron accepting phenol compound, and an electron donating color developing compound, and a reversible thermochromic recording medium using the recording material, Supports reversible thermochromic recording materials that can be reversibly and repeatedly developed and decolored by heating to a temperature range and a color erasing temperature range lower than the color development temperature range, and layers made of this recording material. The present invention relates to a reversible thermochromic recording medium provided in a body shape.
[0002]
[Prior art]
It is well known that colorless or light-colored electron-donating color-forming compounds react irreversibly with an electron-donating compound. Recording paper that applies this principle includes pressure-sensitive paper and heat-sensitive paper. The pressure-sensitive paper includes a base paper coated with a leuco dye solution, which is an electron-donating color-forming compound, in a microcapsule and coated with a binder. In addition, using a base paper coated with an electro-receptive compound such as bisphenol A together with a binder or the like, the microcapsules are destroyed by external pressure, and the electron-donating compound and the electron-accepting compound are melt-reacted. There are things that make use of coloring. Thermal paper is a paper coated with fine powders such as leuco dye, bisphenol A, sensitizer, and storage stabilizer together with a binder, which utilizes the fact that it is colored by the heat supplied from the head of the thermal printer. is there. For example, there is Japanese Patent Publication No. 43-7600.
However, in the pressure sensitive paper and the thermal paper having the above-described configuration, the recording of the used recording paper is not erased and reused as the recording paper again. In recent years, from the viewpoint of saving resources or from the viewpoint of convenience, vigorous technical development has been carried out to thermally and reversibly perform coloring and erasing.
For example, a thermochromic composition using a leuco dye which is an electron donating color developing compound and phenol which is an electron accepting compound is described in, for example, US Pat. No. 3,560,229.
[0003]
In addition, (a) an electron-donating color-forming compound, (b) an electron-accepting compound, and (c) a reaction temperature adjusting solvent, the color is selected with the component (a), and the color density with the component (b) A reversible thermochromic composition in which the color temperature is determined by the component (c) and a composition containing the composition in microcapsules are disclosed in, for example, Japanese Patent Publication Nos. 51-44706 and 51-44707. Gazette, and Japanese Patent Publication No. 51-44708. JP-A-58-191190, JP-A-60-257289, JP-B-4-30355, JP-B-4-30916 disclose an electron-donating color-forming compound, gallic acid or phlorog. A reversible recording medium is disclosed in which a recording layer comprising an electron-accepting compound such as lucinol and a binder such as cellulose acetate is provided on a substrate, an image is formed with heat, and the image can be erased with water or water vapor. However, since these recording media erase images with water or water vapor, the formed images are easily affected by moisture and moisture, and there is a problem in image stability.
Japanese Patent Application Laid-Open No. 63-315287 discloses a solution comprising a compound having a lactone ring as an electron-donating color-forming compound and an alkylphenol liquid at room temperature as an electron-accepting compound without using a binder. In addition, a material is disclosed that is used by being encapsulated in microcapsules and reversibly developing decolorization and color development by heating and cooling. Contrary to the reversible thermochromic recording material of the present invention, this is colorless and transparent when heated, and loses fluidity when cooled and develops color. However, since there is no hysteresis property, recording cannot be held, and it is not suitable as a recording medium.
Also, a proposal for a reversible thermosensitive recording material comprising a leuco dye, an amphoteric compound having a functional group that reacts with the dye to develop or decolor, and a polymer binder is disclosed in JP-A-5-254244. Japanese Laid-Open Patent Publication No. 5-262632, Japanese Laid-Open Patent Publication No. 6-48028, Japanese Laid-Open Patent Publication No. 2-188293, Japanese Laid-Open Patent Publication No. 2-188294, International Publication No. WO90 / 11898, Japanese Laid-Open Patent Publication No. 4-46986, Japanese Laid-Open Patent Publication No. Hei 4- No. 303680, JP-A-4-50289, JP-A-4-50290, JP-A-5-177931, and the like. More specifically, Japanese Patent Application Laid-Open No. 5-254244 discloses an amphoteric compound having a functional group relating to color development or decoloration, which is a complex of gallic acid and 3-methoxypropylamine, crystal violet lactone, and polyvinyl alcohol binder. A heat-sensitive recording material is disclosed. International Publication No. WO 90/11898 discloses a thermosensitive recording material comprising a compound having at least one of a phenolic hydroxyl group or a carboxyl group and having an amino group as a functional group, crystal violet lactone and a methacrylic resin binder. ing. Japanese Patent Application Laid-Open No. 6-210954 discloses a leuco dye and a phenolic electron accepting compound that reversibly changes the leuco dye between a colored state and a decolored state, such as 4'-hydroxy-n-heptaneanilide. There is disclosed a reversible thermosensitive material comprising: However, these reversible thermosensitive recording materials are difficult to control the temperature of color development and color erasing because the color development and color erasing operations occur competitively, and have poor image contrast. There was a problem that the material was deteriorated and the number of repeated use was reduced.
Japanese Patent Application Laid-Open No. 5-124360 discloses a combination of an electron-donating color-forming compound and an electron-accepting compound selected from an organic phosphoric acid compound having a long-chain alkyl group, an aliphatic carboxylic acid compound, and a phenol compound. Thus, a means for selecting a reversible thermochromic composition is disclosed. When this composition is heated to a color development temperature range, both compounds melt and react to cause the color-forming compound to open and color, and by rapidly cooling it, the color development state can be maintained even at room temperature. Yes. When the colored composition is heated to a decoloring temperature range lower than the coloring temperature range, the long-chain alkyl group of the electron-accepting compound aggregates, and the electron-accepting compound becomes a single crystal, which It is presumed that it will be separated and as a result decolored. That is, in the relationship between the electron-donating color-forming compound and the electron-accepting compound, the colored state is maintained by solidifying the two compounds while they are reacted, and the electron-accepting compound is thermally It is said that it separates and crystallizes under conditions to form a single crystal and maintain a decolored state. However, in the reversible thermochromic recording material using this principle, the electron-accepting compounds that can be used are limited to those having a long-chain alkyl group. In addition, when such a color forming composition is used as a recording medium or a display medium, in many cases, a recording layer comprising the composition and a polymer binder is formed on a support. Further, since the decoloring characteristics are greatly affected by the polymer binder, a practical product cannot be obtained without limitation of the polymer binder. In addition, there is a drawback that the decolorization property is not good.
[0004]
[Problems to be solved by the invention]
The present invention relates to a special color-decoloration control polymer in a heat-sensitive recording material that uses an electron-donating color-forming compound and an electron-accepting compound and can be reversibly developed and decolored by heating to a coloring temperature and a decoloring temperature. By specifying the proportion of each component, the above problems were solved, and a color density state with a practical density was obtained by heating to the color temperature range, and when the color state was cooled to room temperature, Or reversible heat that can be maintained for a desired period of time and can be erased by heating to a decoloring temperature range lower than the coloring temperature range, and has a good decoloring property and can maintain a stable decoloring state over time. Discoloration recording material and reversible thermochromic recording medium using the same.
[0005]
[Means for Solving the Problems]
In order to obtain the reversible thermochromic recording material, as a result of various studies, the inventors have retained an electron-donating color-forming compound and an electron-accepting compound in a polymer matrix. Thus, the inventors have found that the desired reversible thermochromic recording material can be obtained by controlling the color-forming compound and the electron-accepting compound in a compatible state or an incompatible state. That is, it has been clarified that the problem can be solved by developing a matrix polymer that retains the electron-donating color-forming compound and the electron-accepting compound and controls the compatible state of both.
As a result of intensive studies on many combinations of electron donating color-forming compounds, electron accepting compounds and color-decoloring / controlling polymers, the present inventors have used phenolic compounds as electron-accepting compounds and developed color-decoloring / controlling polymers: When the weight ratio of the electron-accepting phenol compound to the electron-donating compound is 1: 0.1 to 0.6: 0.01 to 0.09, the electron-accepting phenol compound has a color development temperature range. For example, when heated to 90 ° C. or higher, it is compatible with the polymer, reacts with the electron-donating coloring compound that is in a compatible state regardless of the temperature range, exhibits a colored state, and is cooled to room temperature. In addition, when the colored state is heated to a decoloring temperature range, for example, 40 ° C. to 70 ° C., the electron-accepting phenol compound becomes incompatible with the polymer. So Cut the bond between the electron-donating coloring compound that was in reaction conditions with the, decolored state can be obtained, decolored state has completed the present invention can be maintained even when cooled to room temperature.
[0006]
  The present invention
“1. A reversible thermochromic recording material that can be repeatedly developed and decolored by heating to a coloring temperature and a decoloring temperature, comprising at least a.Shown by the following general formulaAn electron-accepting phenol compound and b. An electron donating color developing compound and c. It has a temperature range that is always compatible with the electron-donating colorimetric compound and a temperature range that is incompatible with the electron-accepting phenol compound, andSaidHas a glass transition temperature below the melting point of the electron-accepting phenol compoundOne or more selected from styrene-butadiene copolymer, styrene-isoprene-styrene copolymer, styrene-acrylic ester copolymer, butadiene polymer, styrene-ethylene-butadiene-styrene copolymer,It consists of a color development / decoloration control polymer, and the mixing ratio of the color development / decoloration control polymer: electron-accepting phenol compound: electron-donating color-forming compound is 1: 0.1-0.6: 0.01- A reversible thermochromic recording material having a decolorization temperature range of 0.09 and a temperature range lower than the color development temperature range.
[0007]
[Chemical 2]

[0008]
(Where R is C_ThreeThese are the above alkyl groups)
2. 2. The reversible thermochromic recording material according to item 1, wherein the color-decoloration controlling polymer has a glass transition temperature of 60 ° C. or lower.
3. 1 itemOr 2 termsA reversible thermochromic recording medium comprising a reversible thermochromic recording layer comprising the reversible thermochromic recording material described in 1 above on a support.
4. An undercoat layer for improving adhesion is provided between the reversible thermochromic recording layer and the support.3The reversible thermochromic recording medium described in the item.
5. A protective layer is provided on the reversible thermochromic recording layer.3Term or4The reversible thermochromic recording medium described in the item.
6. The protective layer is made of a transparent polymer,5The reversible thermochromic recording medium described in the item.
7. A colorant is contained in the reversible thermochromic recording medium,3Term or6The reversible thermochromic recording medium described in any one of the items.
8. A single color or a plurality of reversible thermochromic recording layers made of a reversible thermochromic recording material is formed on a support in a predetermined character, figure or pattern.3Term or7The reversible thermochromic recording medium described in any one of the items.
9. A reversible thermochromic recording material composed of a reversible thermochromic recording material is formed by laminating all or part of a reversible thermochromic recording layer of a single color or a plurality of colors on a support on which predetermined characters, figures or patterns are formed in advance.3Term or7The reversible thermochromic recording medium described in any one of the items. "
It is.
[0009]
The reversible thermochromic recording material of the present invention has a great feature in that it has hysteresis.
When the recording material of the present invention is heated from the initial colorless state, the temperature rises in the colorless state, and when the temperature reaches the color development temperature range, the color is developed. When the temperature is lowered, the colored state is cooled and the initial colorless state is maintained. For example, even when the temperature reaches room temperature, the colored state is maintained and the color is not immediately erased. In order to erase the color, it is necessary to return to the first color development path by heating to the temperature of the color erase. That is, in order to change the color developed state to the color erased state, it can be brought into the initial color erased state by heating and cooling to a color erase temperature range lower than the color developing temperature.
In other words, the path from colorless to colored and the path from colored to colorless are different and have hysteresis.
Because of such hysteresis, it is possible to store a colored record.
Of course, there are differences in the temperature range of the color erasing temperature and the color development temperature, the color development start temperature and the color development saturation temperature in the color change route depending on the compound and composition, but all the recording materials of the present invention are characterized in that they have a hysteresis property and are clearly Record can be obtained.
[0010]
The electron-donating color-forming compound used in the present invention is a colorless or light-colored dye used as a pressure-sensitive / heat-sensitive dye, such as triphenylmethane phthalide dye, fluoran dye, indolyl phthalide dye, and spiropyran dye. , Rhodamine lactam dyes, triphenylmethane dyes, azaphthalide dyes and azomethine dyes. Specific examples will be given below, but it is not limited to these as long as they are always compatible with the color-decoloration / controlling polymer.
3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-chlorophenyl) aminofluorane, 3-diethylamino-7- (2-bromophenyl) aminofluorane, 3-diethylamino- 6-methyl-7-chlorofluorane, 3-diethylamino-6-methyl-7- (3-trifluoromethylphenyl) aminofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluor Oran, 3-diethylamino-7-piperidinofluorane, 3-diethylamino-7- (N-ethyl-N-phenyl) aminofluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylamino-6 -Chloro-7- (2,3-dicyclohexylphenyl) aminofluorane 3-diethylamino-6-chloro-7-phenylaminofluorane, 3-diethylamino-6-methyl-7- (2,4-dimethylphenyl) aminofluorane, 3-diethylamino-6-chloro-7- (3- Trifluoromethylphenyl) aminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (3-trifluoromethylphenyl) aminofluorane, 3-dipropylamino-7- Chlorofluorane, 3-diethylamino-6-methyl-7- (3-trichloromethylphenyl) aminofluorane, 3-diethylamino-7- (2-methoxycarbonylphenyl) aminofluorane, 3-diallylamino-7,8 -Benzofluorane, 3-diethylamino-5-chloro-7- (N-α -Phenylethyl) aminofluorane, 3-diethylamino-5-methyl-7- (N-phenylethyl) aminofluorane, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-7- Medoxyfluorane, 3-diethylamino-6-diethylaminofluorane, 3-diethylamino-7- (p-toluidino) fluorane, 3-diethylamino-5-chloro-7- {N-benzyl-N- (trifluoromethylphenyl) )} Aminofluorane, 3-dibutylamino-7- (2-chlorophenyl) aminofluorane, 3-diethylamino-7-acetaminofluorane, 3-dibutylamino-6-chloro-7-ethoxyethylaminofluorane, 3-Dibutylamino-7- (2-fluorophenyl) aminophen Oran, 3-dibutylamino-7,8-benzofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-dimethylamino-5,7 -Dimethylfluorane, 3-cyclohexylamino-6-chlorofluorane, 3-cyclohexylamino-6-bromofluorane, 3-cyclohexylamino-6-chloro-7- (2-chlorophenyl) aminofluorane, 3- ( N-methyl-N-cyclohexyl) amino-7,8-benzofluorane, 3- (N-ethyl-Nn-octyl) amino-7,8-benzofluorane, 3- (N-ethyl-N- i-amyl) amino-7,8-benzofluorane, 3- (N-ethyl-Ni-amyl) amino-7-chlorofluorane, -(N-methyl-N-cyclohexyl) amino-6-methyl-7- (3-trifluoromethylphenyl) aminofluorane, 3- (N-methyl-Ni-propyl) amino-6-methyl-7 -Phenylaminofluorane, 3- (N-benzyl-N-cyclohexyl) amino-5,6-benzo-7- (4-bromonaphthyl) aminofluorane, 3- (Ni-butyl-N-methyl) Amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Ni-amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-hexyl) Amino-7-phenylaminofluorane, 3- (Nn-amyl-N-methyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-methyl-N-cyclohexyl) Amino-6-methyl-7-phenylaminofluorane, 3- (N-methyl-Nn-propyl) amino-6-methyl-7-phenylaminofluorane, 3- (Nn-propyl-N- i-propyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-Sec-butyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl- N-n-amyl) amino-6-methyl-7-phenylmethylfluorane, 3-di-n-octylamino-7- (4-chlorophenyl) aminofluorane, 3-n-octylamino-7- (4 -Chlorophenyl) aminofluorane, 3- (Nn-butyl-Nn-amyl) amino-7- (4-acetyl-phenyl) aminofluorane, 3-n-octylamino-7- (4 Chlorophenyl) aminofluorane, 3-n-cetylamino-7- (4-chlorophenyl) aminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-7- {bis (4-chlorophenyl) ) Methyl} aminofluorane, 3-morpholino-7- {N-propyl-N- (4-trifluoromethylphenyl)} aminofluorane, 3-pyrrolidino-6-chloro-7-phenylaminofluorane, 3- Pyrrolidino-6-methyl-7- (3-trifluoromethylphenyl) aminofluorane, 3-morpholino-7- {N-propyl-N- (3-trifluorophenyl)} aminofluorane, 3- (N- Ethyl-N-ethoxyethyl) amino-7,8-benzofluorane, 3- {N-ethyl-N- (2-ethoxy) Propyl)} amino-6-methyl-7-phenylamino fluoran, 3- (N-ethyl--N- tetrahydrofurfuryl) amino-6-methyl-7-phenylamino fluoran, 3-
(N-methyl-N-phenyl) amino-7-aminofluorane, 3- (N-methyl-N-phenyl) amino-7-N-methylaminofluorane, 3- (N-methyl-N-phenyl) Amino-7-dimethylaminofluorane, 3- (N-methyl-N-phenyl) amino-7-dipropylaminofluorane, 3- (N-ethyl-N-phenyl) -6-methyl-7- {N -Ethyl-N- (4-methylphenyl)} aminofluorane, 3- (N-ethyl-N-phenyl) amino-7-dimethylaminofluorane, 3- (N-ethyl-N-phenyl) amino-7 -Dipropylaminofluorane, 3- (N-ethyl-N-phenyl) amino-7-aminofluorane, 3- (N-phenyl-N-propyl) amino-7-aminofluorane, 3- (N- ethyl N-phenyl) amino-7-N-methylaminofluorane, 3- (N-propyl-N-phenyl) amino-7-N-methylaminofluorane, 3- {N-methyl-N- (4-methyl) Phenyl)} amino-5-methoxy-7-dibenzylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-6-tert-butyl-7- (4-methylphenyl) amino Fluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-7- (2-methoxybenzoyl) aminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino -7-acetylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-7-dibenzylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} Ami -7-diethylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-7-ethylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino- 7-aminofluorane, 3- (N-methyl-N-phenyl) amino-6-methyl-7-phenylaminofluorane, 3- (3-trifluoromethylphenyl) amino-6-diethylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-6-methyl-7-phenylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7- (N- Methyl-N-phenyl) aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7- (α-phenylethyl) aminofluorane, 3- {N-ethyl-N (4-Methylphenyl)} amino-7-aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7-butylaminofluorane, 3- {N-ethyl-N- ( 4-methylphenyl)} amino-7-dibenzylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7- {bis (4-methylbenzyl)} aminofluorane, 3 -{N-ethyl-N- (4-methylphenyl)} amino-7-benzoylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-5-methyl-7-dibenzyl Aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-5-chloro-7-dibenzylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino 6-methylfluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-5-methoxyfluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7, 8-benzofluorane, 3- {N-propyl-N- (4-methylphenyl)} amino-6-methyl-7- {N-emer-N- (4-methylphenyl)} aminofluorane, 3- {N-propyl-N- (4-methylphenyl)} amino-7-aminofluorane, 3- {N-ethyl-N- (4-ethylphenyl)} amino-7-aminofluorane, 3- {N -Methyl-N- (4-ethylphenyl)} amino-7-aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7-diethylaminofluorane, 3- {N-ethyl -N- (4-ethylpheny L)} amino-7-aminofluorane, 3- {N-propyl-N- (4-ethylphenyl)} amino-7-aminofluorane, 3- {N-methyl-N- (2,4-dimethyl) Phenyl)} amino-7-benzylaminofluorane, 3- {N-ethyl-N- (2,4-dimethylphenyl)}-7-aminofluorane, 3- {N-methyl-N- (2,4 -Dimethylphenyl)} amino-7-methylaminofluorane, 3- {N-ethyl-N- (2,4-dimethylphenyl)} amino-7-ethylaminofluorane, 3- {N-ethyl-N- (2,4-Dimethylphenyl)} amino-7-benzylaminofluorane, 3- {N-propyl-N- (2,4-dimethylphenyl)} amino-7-aminofluorane, 3- {N-methyl -N- (4-Chloroph Yl)} amino - aminofluoran, 3- {N-ethyl--N- (4- chlorophenyl)} amino-7-amino fluoran, 3-
{N-propyl-N- (4-chlorophenyl)} amino-7-aminofluorane, 3-cyclohexylamino-7-bromoaminofluorane, 2,7-dichloro-3-n-butylamino-6-methylfluor Orane, 3-di-n-butylamino-6,7-butylenefluorane, 3-amino-5-methylfluorane, 2-methyl-3-amino-6-methyl-7-methylfluorane,
1,3,3-trimethylindolino-6'-nitrobenzopyrospirane, 1,3,3-trimethylindolino-6'-nitro-8'-methoxybenzopyrrirospirane, 1,3,3-trimethyl Indolino-6'-bromobenzopyrospirane, 1,3,3-trimethylindolino-8'-methoxybenzopyrospirane, 1,3,3-trimethylindolino-benzopyrispirane, 1,3,3 3-trimethylindolino β-naphthopyrrirospirane,
Tris (4-dimethylaminophenyl) methane-2-carboxylate (CVL), bis (4-dimethylaminophenyl) phenylmethane-2-carboxylate (MGL), bis (4-dimethylaminophenyl)-(4-chloro ) Phenylmethane-2-carboxylate, bis (4-dimethylaminophenyl)-(4-diethylamino) phenylmethane-2-carboxylate, bis (4-dibutylaminophenyl) phenylmethane-2-carboxylate, {2- Hydroxy- (4-diethylamino) phenyl}-(2-methoxy-5-methylphenyl) phenylmethane-2-carboxylate, {2-hydroxy- (4-dimethoxyamino) phenyl}-(2-hydroxy-5-chlorophenyl) ) Phenylmethane-2-carboxylate , (4-dimethylaminophenyl)-(2-hydroxy-4-chloro-5-methoxyphenyl) phenylmethane-2-carboxylate, 3- {2-ethoxy- (4-diethylamino) phenyl} -3- (2 -Methyl-1-ethylindol-3-yl) -4-azaphthalide, 3- {2-ethoxy- (4-diethylamino) phenyl} -3- (2-methyl-1-n-octylindol-3-yl) -4-azaphthalide, 3,3-bis (2-methyl-1-ethylindol-3-yl) phthalide, 3- {2-methoxy- (4-diethylamino) phenyl} -3- (2-methyl-1- Ethylindol-3-yl) -phthalide, 3- {2-methyl- (4-diethylamino) phenyl} -3- (1,2-dimethylindol-3-yl) -phthalate 3,3-bis (2-methyl-1-octylindol-3-yl) phthalide, rhodamine anilinolactam, rhodamine-2-chloroanilinolactam, rhodamine-4-chloroanilinolactam, bis {2- Methyl- (4-dimethylamino) phenyl}-{(2,5-dimethylamino) phenyl} methane.
[0011]
Preferable examples of the electron-accepting phenol compound used in the present invention are those having a melting point of 70 ° C. or higher. When an electron-accepting phenol compound having a melting point of 70 ° C. or less and a color-decoloration controlling polymer having a glass transition temperature of around 60 ° C. are used, the electron-accepting phenol compound starts to melt when heated to the decoloring temperature range. As a result, there is a tendency that decoloration hardly occurs. For this reason, it is preferable to use an electron-accepting phenol compound of 70 ° C. or higher. When a specific example of an electron-accepting phenol compound is shown, an ester of gallic acid is preferable, more specifically,
N-propyl gallate,
N-butyl gallate,
I-amyl gallate,
Lauryl gallate,
Cetyl gallate,
Myristyl gallate,
Stearyl gallate,
Examples include behenyl gallate. However, it is not limited to these.
The color development / decoloration control polymer used in the present invention is always compatible with the electron donating color developing compound from the viewpoint of color development / decoloration control, and is compatible with the electron accepting phenol compound and changes in compatibility with the electron accepting phenol compound. It must be a polymer that can cause Further, the glass transition temperature of the polymer is involved in color development and decoloration in relation to the electron-accepting phenol compound. If the glass transition temperature of the color-decoloration controlling polymer is high, decoloring is difficult to occur, and if it is low, decoloring is easily controlled. From this result, the glass transition temperature of the color development / decoloration control polymer is preferably 60 ° C. or less. That is, when the glass transition temperature exceeds 60 ° C., it becomes difficult to take an incompatible state with the electron-accepting phenol compound at the time of decoloring. That is, since the color-decoloration controlling polymer is in a hard state, it is difficult to cause phase separation, and it becomes difficult to decolorize or it takes time to decolorize. The color development is relatively unaffected by the glass transition temperature of the color development / decoloration control polymer, but when the glass transition temperature exceeds 60 ° C., the color development response and contrast tend to deteriorate. Therefore, it is preferable to use a polymer having a glass transition temperature of 60 ° C. or lower.
[0012]
  In addition, the color development / decoloration control polymer used in the present invention is clearly compatible or incompatible with the electron-accepting phenol compound under specific conditions, that is, from the viewpoint of good color development control, a styrenic polymer and a diene type polymer. Polymers are preferred. From the above, exemplifying the color development / decoloration control polymer used in the present invention is preferably a styrene polymer and a diene polymer, specifically,Styrene-butadiene copolymer, styrene-isoprene-styrene copolymer, styrene-acrylic ester copolymer, butadiene polymer, styrene-ethylene-butadiene-styrene copolymerEtc.
[0013]
In the present invention, the mixing ratio of the color development / decoloration control polymer: electron-accepting phenol compound: electron-donating color-forming compound is a weight ratio of 1: 0.1 to 0.6: 0.01 to 0.09. If the ratio of the electron-accepting phenol compound exceeds this, it becomes difficult to control the compatibility and incompatibility necessary for color development and decolorization, and the colored state cannot be maintained even when the recording material in the heated colored state is cooled. There is a trend. That is, the three components of the color-decoloration controlling polymer, the electron-accepting phenol compound, and the electron-donating color-forming compound are not completely compatible with each other. As a result, the color density at the time of cooling is lowered. On the other hand, if the ratio is lower than this, a practically sufficient color density cannot be obtained, and as a result, the contrast is lowered, which is not preferable for use as a recording material. In addition, if the ratio of the electron-donating color-forming compound exceeds this, some electron-donating color-forming compounds may not always be compatible with each other, and as a result, electron accepting properties may be generated. Even if the phenolic compound changes compatibility or incompatibility with the color-decoloration controlling polymer, it can always react with the electron-donating color-forming compound, so that decoloration is difficult to occur. Since the base density is high, the resulting contrast is not preferable. On the other hand, if the ratio is lower than this, it is not preferable because a sufficient color density cannot be obtained as in the case where the ratio of the electron-accepting phenol compound is decreased. Further, the blending ratio of the electron-accepting phenol compound to the electron-donating color-forming compound is particularly preferably in the range of 1: 0.1 to 0.9 by weight. When the proportion of the electron-accepting phenol compound is increased, the color density during cooling tends to be lowered, and when the proportion of the electron-accepting phenol compound is decreased, the color density is not obtained or the contrast tends to be deteriorated. This is not preferable.
From the results of studying these blending ratios, the respective relationships are as follows. That is, the blending ratio of the color development / erasing control polymer and the electron-accepting phenol compound affects the color density and the color erasing speed. The mixing ratio of the color development / erasing control polymer and the electron donating color-forming compound affects the color density and the base density. It has been clarified that the compounding ratio of the electron-accepting phenol compound and the electron-donating color-forming compound affects the color density and contrast. Therefore, a practical recording material cannot be obtained without limitation of the blending ratio as described above, and it is necessary to limit the blending ratio in producing a desired recording material. The mechanism of color development / decoloration in the present invention is caused particularly by the compatibility / incompatibility of the color development / decoloration control polymer and the electron-accepting phenol compound. Limiting the ratio is important.
[0014]
The reversible thermochromic recording medium of the present invention comprises the recording material arranged in a layer on a support, and the support includes a transparent, translucent or opaque polymer film or sheet, synthetic paper and processed paper, glass plate In addition, a metal plate or the like is used, and a recording layer is directly provided on the support, or an undercoat layer is once provided on the support to improve adhesion between the support and the recording layer, and a recording layer is provided thereon. Also good. Such an undercoat layer has the effect of imparting heat insulation and the like in addition to improving adhesion. In addition, the surface of the recording medium is transparent on the surface of the recording medium in order to prevent fusion between the surface of the recording medium and the thermal head, to improve the scratch resistance of the recording layer, to prevent oxidation of the recording layer, and to prevent contamination of the recording layer by harmful gases. A protective layer may be provided. The protective layer can be formed by vapor deposition of an inorganic material or coating with a polymer solution or the like, or can be formed by laminating polymer films. In order to laminate the polymer film, an adhesive layer or an adhesive layer may be provided between the recording layer and the recording layer.
[0015]
The reversible thermochromic recording medium using the reversible thermochromic recording material of the present invention comprises a colorant in a recording layer or a layer other than the recording layer, for example, a support, an undercoat layer, a protective layer, an adhesive or an adhesive layer. It is possible to change the color of the colorant and the color of the colorant mixed with the electron-donating color-forming compound in a colored state from color to color. The type and amount of the colorant that can be used here, when present in the recording layer, do not inhibit the color reaction between the electron-accepting phenol compound and the electron-donating color-forming compound, and It is necessary that the color control polymer and the electron-accepting phenol compound do not hinder the change in compatibility and incompatibility, and any material that satisfies such requirements can be used. In addition, when a layer other than the recording layer is included, it is not preferable to add such a material that causes a significant decrease in contrast. Similarly, an additive such as an ultraviolet absorber may be added to protect the recording material.
The reversible thermochromic recording material of the present invention can be used as a reversible thermochromic recording medium by forming a predetermined character, figure or pattern on a support. That is, when the recording layer is heated to the color development temperature range, part or all of the recording layer is colored or discolored, and recording or display becomes possible. At this time, if the recording layer is formed by applying a reversible thermochromic recording material that develops different colors in addition to a single color to a different pattern such as a stripe or matrix, multiple colors can be developed. It becomes possible.
Furthermore, the reversible thermochromic recording material of the present invention has the ability of the colored state to hide the ground. Therefore, a predetermined character, figure or pattern can be formed on the support in advance, and the recording layer can be laminated thereon. By heating the recording layer to a coloring temperature range or a decoloring temperature range, a part or all of the recording layer is colored, decolored or discolored, and a part of characters, figures or patterns on the support Alternatively, the whole can be concealed or seen through to enable reversible recording or display. In addition, predetermined characters, figures, and patterns can be formed on both the recording layer and the support and used in combination.
The recording material as used in the present invention is a term including a display material.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, the embodiment of the present invention will be described together with the operation.
The reversible thermochromic recording material of the present invention comprises a color development control polymer: an electron accepting phenol compound: an electron donating color developing compound in a weight ratio of 1: 0.1 to 0.6: 0.01 to 0.00. It can manufacture by melt | dissolving in a volatile organic solvent in the ratio of 09, and making it a mixed solution. It can also be produced by dispersing an electron-accepting phenol compound and an electron-donating color developing compound in a color-decoloration controlling polymer emulsion formed by emulsion polymerization. A reversible thermochromic recording medium can be produced by applying this mixed solution to a support and drying.
[0017]
The reversible thermochromic recording material of the present invention can arbitrarily control the time for maintaining the colored state. That is, the color development state can be maintained for a long period of one month or longer, or the color can be erased by several tens of minutes. The control of the color development state can be controlled by selecting the combination of the electron-accepting phenol compound and the color-decoloration controlling polymer and the blending ratio thereof.
For example, when gallic acid esters (esters such as n-propyl, n-butyl, i-amyl, stearyl, cetyl, lauryl, etc.) and styrene-butadiene copolymer or styrene- (meth) acrylic ester copolymer were used in combination, the color developed. The reversible thermochromic recording material can maintain a colored state for more than one month at room temperature. In addition, when a gallic acid ester and a styrene-isoprene-styrene copolymer are used in combination, the reversible thermochromic recording material that has developed color can be brought to a decolored state by leaving it at room temperature.
[0018]
Since the reversible thermochromic recording material of the present invention can be used as a recording medium arranged in a layer on a support, the organic solvent used when forming a mixed solution as a solution is a solvent that does not participate in the color-decoloration reaction. In the case of using a solvent involved in the reaction, it is necessary to volatilize and remove it from the system during the color development reaction.
The recording material layer provided on the support is a dry film having a thickness of preferably 1 μm to 30 μm, more preferably 2 μm to 6 μm.
The recording medium of the present invention can be colored by a thermal transfer printer or the like to display the recording, and can be decolored by blowing hot air at a decoloring temperature.
[0019]
Next, an embodiment will be described from the aspect of the operation of the present invention. The reversible thermochromic recording material of the present invention exhibits hysteresis and does not lose color even when the composition in a decolored state is heated to develop a color and is cooled to room temperature.
FIG. 1 shows the color development and color erasing phenomena of the thermal recording material of the present invention obtained by evaporating and removing an organic solvent from an organic solvent solution of an electron donating color developing compound, an electron accepting phenol compound and a color development / decoloration control polymer. Shown in In FIG. 1, when the material in the decolored state A is heated and reaches D (the temperature in the vicinity of D or higher is referred to as a color development temperature range) via B and C, the electron donating color-forming compound in the thermal recording material The electron-accepting phenol compound and the color-decoloration controlling polymer are in a compatible state and develop color, and when this is cooled to room temperature, the route from the color-degraded state A to the color-formed state D is different from D to E. The color development state is maintained. Next, when the thermal recording material in the E state is heated to a temperature between B and C (the temperature range in the vicinity thereof is referred to as a decoloring temperature range) and changes from the E state to the B and C states, the electron-accepting phenol compound is extinguished. It becomes incompatible with the color control polymer, reacts with the electron donating color-forming compound that is in a colored state, and the thermal recording material becomes decolored. When this is cooled to room temperature, it does not return to the E state but becomes the A state and the decolored state is maintained and is stable over time.
Thus, there is a great feature in that the reaction shows a hysteresis that is reversible through different paths.
Crystal violet lactone as an electron donating color developing compound
(Hereinafter referred to as CVL), an example of the reversible thermochromic recording material of the present invention produced by evaporating and removing a solvent from a homogeneous solution of stearyl gallate as an electron-accepting phenol compound and a styrene-butadiene copolymer as a color-decoloration controlling polymer [X The difference between the material [Y] obtained by evaporating and removing the solvent from the homogeneous solution of CVL and styrene-butadiene copolymer, and the material [Z] produced by evaporating and removing the solvent from the homogeneous solution of stearyl gallate and styrene-butadiene copolymer. This will be described in more detail based on a thermally analyzed data by scanning thermal analysis (hereinafter referred to as DSC). The DSC measurement was performed using a DSC-SSC580 model manufactured by Seiko Denshi Kogyo Co., Ltd. at a temperature rising rate of 5 ° C./min.
[0020]
FIG. 2 line a shows a case where the thermal recording material [X] is heated to 120 ° C. which is a color development temperature range and then cooled to room temperature, and a sample in a color development state is used. X] is a result obtained by heating DSC to 60 ° C. which is a decoloring temperature range, cooling to room temperature, and performing DSC measurement using a sample in a decoloring state. The endothermic peak 2-1 and the endothermic peak 2-11 are associated with the change of the polymer to an amorphous state, and the endothermic peaks 2-2, 2-3, and 2-4 are slightly different in terms of energy. This is associated with the thermal recording material in which the states are mixed, and the endothermic peaks 2-12 and 2-14 are also associated with the thermal recording material in which the coloring states having slightly different energies in the same state are mixed. . The endothermic peak 2-15 is associated with the melting of stearyl gallate that is not yet involved in the reaction with CVL in the temperature rising process. That is, the endothermic peak 2-15 in FIG. 2 line b indicates that in the decolored state, stearyl gallate is in an incompatible state and exists independently. On the other hand, in FIG. 2 line a, there is no endothermic peak corresponding to 2-15. If incompatible stearyl gallate is present in the sample, an endothermic peak corresponding to 2-15 appears to occur near 100 ° C. near the melting point, but no endothermic peak exists at that point. The colored sample [X] used for the measurement shows that the three components CVL, stearyl gallate and styrene-butadiene copolymer are in a compatible state.
[0021]
FIG. 3 shows the result of DSC measurement of the sample [Y] heated to 60 ° C. in the decoloring temperature range and then cooled to room temperature. FIG. 4 shows the material [Y] up to 120 ° C. in the color development temperature range. The results of DSC measurement after heating and cooling to room temperature are shown. The endothermic peaks 3-1 and 4-1 shown in FIGS. 3 and 4 are endotherms when the polymer is in an amorphous state, and since there is almost no difference between them, the colored or decolored state is observed. In any state, this suggests that the electron-donating color-forming compound is homogeneously dissolved in the color-decoloration controlling polymer.
[0022]
FIG. 5 shows the results of DSC measurement using a sample [Z] heated to 70 ° C. in the decoloring temperature range and then cooled to room temperature. The endothermic peak 5-1 is due to the amorphous state of the color development / decoloration control polymer, which is a broad endothermic peak as compared to FIGS. 2, 3 and 4, and the endotherm in a wide temperature range. It is caused by the influence of the electron-accepting phenol compound, that is, it exists in an incompatible state. Further, the endothermic peak 5-2 is accompanied by the dissolution of the electron-accepting phenol compound existing in an incompatible state. Note that the temperature at which the endothermic peak appears may be slightly shifted due to the influence of coexisting substances.
[0023]
Summing up the results of the above DSC measurement, the mixture of the color development / decoloration control polymer and the electron donating color developing compound is always in a compatible state from room temperature to the color erasing temperature range to the color development temperature range. Therefore, also in the present invention, it is necessary to select an electron-donating color-forming compound that is always compatible with the color-decoloration controlling polymer, and it is necessary to make a preferable combination. In addition, the electron-accepting phenol compound is dissolved in the color development temperature range and is compatible with the color-decoloration controlling polymer, so that it always reacts with the color-forming compound in a compatible state and develops color. When this product is cooled to room temperature, the compatible state is maintained and the colored state can be maintained. When the electron-accepting phenolic compound involved in the reaction is heated from room temperature to the decoloring temperature range, it becomes incompatible with the color-decoloration controlling polymer, and the bond with the color-developing compound is broken, resulting in decoloration. To do. Even when this is returned to room temperature, the incompatible state is maintained, so that stable decoloring can be maintained.
[0024]
Next, in the decolored state, X-ray diffraction measurement was performed in order to clarify the crystal state of the electron-accepting phenol compound and the color-decoloring control polymer.
The X-ray diffraction measurement result of the reversible thermochromic recording material [X] in the decolored state is shown in FIG. FIG. 7 shows the X-ray diffraction measurement of the styrene-butadiene copolymer, and FIG. 8 shows the X-ray diffraction measurement result of stearyl gallate.
In FIG. 8, stearyl gallate is 2θ / deg. 2 to 25, some crystallization peaks are observed, especially 2θ / deg. There is a large crystallization peak between 2-7. In FIG. 7, the styrene-butadiene copolymer is 2θ / deg. A relatively small crystallization peak 7-2 is observed near 23.
On the other hand, in FIG. 6, the reversible thermochromic recording material [X] in the decolored state has small peaks indicated as 6-1 and 6-2, but 6-2 indicates crystallization of the styrene-butadiene copolymer. Is based. 6-1 is based on stearyl gallate, and it can be estimated that stearyl gallate is hardly crystallized.
As described above, the present invention relates to the relationship between the color development / decoloration control polymer, the electron accepting phenol compound, and the electron donating color developing compound, particularly the compatibility between the color development / decoloration control polymer and the electron accepting phenol compound. Coloring and decoloring are reversibly performed by reversible change of compatibility. The state in which the electron-accepting phenol compound is incompatible with the polymer may be in a crystalline state or an amorphous state, and is not limited to being separated from the polymer in a specific state. That is, no exothermic peak due to crystallization of the phenol compound is observed in FIG. Further, from the measurement result of X-ray diffraction in FIG. 6, since the clear crystallization peak of the phenol compound is not recognized, it is clear that the phenol compound is different from the decoloration due to the aggregation crystallization of the long chain alkyl group. It is.
[0025]
【Example】
Hereinafter, an example will be described.
[0026]
Example 1
20 parts by weight of styrene-butadiene copolymer
(Product name “Asmer”, manufactured by Asahi Kasei Kogyo Co., Ltd., Tg = −60 ° C.)
10 parts by weight of stearyl gallate
1 part by weight of crystal violet lactone (hereinafter CVL)
The above composition was dissolved in 170 parts by weight of tetrahydrofuran (hereinafter THF) to prepare a reversible thermochromic recording material solution. This solution was applied to a polypropylene synthetic paper having a thickness of 110 μm (trade name “YUPO FBD # 110”, manufactured by Oji Yuka Co., Ltd.) using a wire bar, and then heated and dried at 100 ° C. A recording layer made of a reversible thermochromic recording material having a thickness of 4 μm and colored was provided to prepare a recording medium. When this recording medium was heated to 60 ° C. and cooled to room temperature (20 ° C.), the blue-purple color disappeared and the white color close to that of the base synthetic paper was obtained. When this medium was heated to 120 ° C., cooled to room temperature, and then heated to 60 ° C. and then cooled to room temperature, coloring and decoloring could be performed reversibly. The optical density of the colored state and the decolored state at this time was measured using a Macbeth densitometer RD-915, and showed an OD value of 1.52 in the colored state and 0.14 in the decolored state. was gotten. Hereinafter, the same machine was used for OD value measurement.
[0027]
Example 2
20 parts by weight of styrene-butadiene copolymer
10 parts by weight of stearyl gallate
1 part by weight of CVL
The above composition was dissolved in 170 parts by weight of a mixed solvent of methyl ethyl ketone (abbreviation MEK) and toluene 1: 1 to prepare a reversible thermochromic recording material solution. This solution was applied to a polypropylene synthetic paper having a thickness of 110 μm using a wire bar. This was heated and dried at 120 ° C. to provide a recording layer made of a reversible thermochromic recording material having a thickness of 4 μm and colored blue-violet. A 5% methylcellulose (trade name “Metroses SM-25”, manufactured by Shin-Etsu Chemical Co., Ltd.) aqueous solution was applied onto the recording layer using a wire bar, and then dried by heating to form an intermediate layer having a thickness of 2 μm. . On this intermediate layer, a UV curable epoxy resin (trade name “ADEKA OPTMER KR510”, manufactured by Asahi Denka Kogyo Co., Ltd.) was applied using a wire bar, and then a cured film having a thickness of 2 μm using a 400 W mercury lamp. To prepare a recording medium with a protective layer. An image is formed on this recording medium using a thermal transfer printer (trade name “PC-PR150n”, manufactured by NEC Corporation), and then this recording medium is passed between rubber heat rolls set at 65 ° C. The image has been erased. When the optical density of the colored state and the decolored state at that time was measured, the OD value was 1.50 in the colored state and 0.16 in the decolored state. In addition, the same coloring and erasing operations as those described above were repeated for 30 cycles, but the thermal head of the printer and the protective layer surface of the recording medium were not fused, and the OD value did not change significantly. It was.
[0028]
Example 3
A polyethylene terephthalate (PET sheet) with a thickness of 100 μm was coated with a 5% methylcellulose aqueous solution using a wire bar and dried by heating to form an undercoat layer with a thickness of 2 μm. next,
20 parts by weight of styrene-butadiene copolymer
10 parts by weight of stearyl gallate
1 part by weight of CVL
The above composition was dissolved in 170 parts by weight of a mixed solvent of MEK and toluene 1: 1 to prepare a reversible thermochromic recording material solution (solution A). next,
20 parts by weight of styrene-butadiene copolymer
10 parts by weight of stearyl gallate
Rhodamine B lactam 1 part by weight
Was dissolved in 170 parts by weight of a mixed solvent of MEK and toluene 1: 1 to prepare a solution (B solution) of a reversible thermochromic recording material.
A PET sheet provided with the undercoat layer is made of a reversible thermochromic recording material having a thickness of 4 μm by separately coating the A solution and the B solution using a gravure plate so as to form a stripe having a width of 8 mm, followed by heating and drying. A recording medium provided with a recording layer capable of coloring blue-purple and red in a stripe pattern was produced.
A 5% methylcellulose aqueous solution is applied onto the recording medium using a wire bar and dried to form an intermediate layer having a thickness of 2 μm, and a UV curable epoxy resin is further formed on the intermediate layer using a wire bar. After coating, a cured film having a thickness of 2 μm was formed using a 400 W mercury lamp, and a recording medium with a protective layer was produced.
Using the thermal transfer printer, the recording medium could be colored in two colors. Further, it was possible to erase the color using hot air from a dryer at about 80 ° C.
[0029]
Example 4 to21
  Formulation Example 4 in Table 121Each of the above compositions was dissolved in 170 parts by weight of THF to prepare a solution of reversible thermochromic recording material, applied to polypropylene synthetic paper using a wire bar, and then dried by heating to reversible thermochromic recording on synthetic paper. A recording layer made of the material was formed. Further, a 5% methylcellulose aqueous solution was applied onto the recording layer using a wire bar, and then heated and dried to form an intermediate layer having a thickness of 2 μm. Further, a UV curable epoxy resin was applied on the intermediate layer to the wire bar. Then, a cured film having a thickness of 2 μm was formed using a 400 W mercury lamp to produce a recording medium with a protective layer. In any of the examples, an image could be formed using the thermal transfer printer. Further, the image could be erased by passing between rubber heat rolls set at 75 ° C. Further, this color development and color erasing could be repeated. Table 2 shows the measured optical density values in the colored state and the decolored state of each example.
[0030]
[Table 1]

[0031]
(註)
CVL: Yamada Chemical Co., Ltd., crystal violet lactone (blue purple)
NC-BK: Hodogaya Chemical Co., Ltd., fluoran leuco dye (black)
APT: Yamada Chemical Co., Ltd., fluoran leuco dye (green)
OR-55: manufactured by Yamada Chemical Co., Ltd., fluoran leuco dye (orange)
NBP-1: Yamamoto Kasei Co., Ltd., azaphthalide leuco dye (blue)
NCY-2 [1]: Hodogaya Chemical Co., Ltd., azomethine leuco dye
(yellow)
TH-107: Hodogaya Chemical Co., Ltd., fluoran leuco dye (black)
Styrene-butadiene copolymer: trade name “Asmer”, manufactured by Asahi Kasei Corporation, Tg = −60 ° C.
Styrene-acrylic ester copolymer: Trade name “Hymer TB-1000F”, manufactured by Sanyo Chemical Industries, Ltd., Tg = 58 ° C.
Butadiene polymer: Trade name “RB-820”, manufactured by Nippon Synthetic Rubber Industry Co., Ltd., Tg = −12 ° C.
Styrene-isoprene-styrene copolymer; trade name “SIS-5000”, manufactured by Nippon Synthetic Rubber Industry Co., Ltd., Tg = −70 ° C.
Styrene-ethylene-butadiene-styrene copolymer: trade name “Clayton G-1650”, manufactured by Shell Japan, Tg = −42 ° C.
Vinyl chloride-vinyl acetate copolymer: Trade name “Denka Vinyl 1000A”, manufactured by Denki Kagaku Kogyo Co., Ltd., Tg = 65 ° C.
Poly (p-vinylphenol): Trade name “Marcalinker MB”, manufactured by Maruzen Petrochemical Co., Ltd., Tg = 147 ° C.
Polymethylmethacrylate: trade name “Dianar BR-77”, manufactured by Mitsubishi Rayon Co., Ltd., Tg = 80 ° C.
[0032]
[Table 2]

[0033]
Comparative Examples 1-10, 13
  Formulation examples 23 to 32 in Table 3And Formulation Example 22 in Table 1Each of the above compositions was dissolved in 170 parts by weight of THF, and this solution was applied to a synthetic paper made of polypropylene having a thickness of 110 μm using a wire bar. This was heated and dried at 120 ° C. to provide a recording layer having a thickness of 4 μm. A 5% methylcellulose aqueous solution was applied to the recording layer using a wire bar and then dried by heating to form an intermediate layer having a thickness of 2 μm. On this intermediate layer, a UV curable epoxy resin was applied using a wire bar, and then a cured film having a thickness of 2 μm was formed using a 400 W mercury lamp, to produce a recording medium with a protective layer. Using this recording medium, the color density and decoloring density obtained in the same manner as in Example 2 were measured and are shown in Table 4.
[0034]
Comparative Example 11
18.6 parts by weight of epoxy resin
(Product name “ADEKA RESIN EP-4000”, manufactured by Asahi Denka Kogyo Co., Ltd.)
1.4 parts by weight of triethylenetetramine
10 parts by weight of stearyl gallate
1 part by weight of CVL
The above composition was dissolved in 180 parts by weight of toluene, and this solution was applied to a polypropylene synthetic paper having a thickness of 110 μm using a wire bar. Then, this was heated and dried at 80 ° C. to remove the solvent, and then heated and cured at 80 ° C. for 24 hours to provide a recording layer having a thickness of 4 μm. Thereafter, a protective layer was produced in the same manner as in Comparative Examples 1-10. Using this recording medium, the color density and decoloring density obtained in the same manner as in Example 2 were measured and are shown in Table 4.
[0035]
Comparative Example 12
6.4 parts by weight of polyol
(Brand name "Takelac U-25" 75% butyl acetate solution, manufactured by Takeda Pharmaceutical Company Limited)
13.6 parts by weight of polyisocyanate
(Brand name "Takenate D-110N" 75% ethyl acetate solution, manufactured by Takeda Pharmaceutical Company Limited)
10 parts by weight of stearyl gallate
1 part by weight of CVL
The above composition was dissolved in 145 parts by weight of MEK, and this solution was applied to a polypropylene synthetic paper having a thickness of 110 μm using a wire bar. Then, this was heated and dried at 80 ° C. to remove the solvent, and then heated and cured at 80 ° C. for 24 hours to provide a recording layer having a thickness of 4 μm. Thereafter, a recording medium with a protective layer was produced in the same manner as in Comparative Examples 1 to 10. Using this recording medium, the color density and decoloring density obtained in the same manner as in Example 2 were measured and are shown in Table 4.
The recording materials obtained in Comparative Examples 11 and 12 were printed using a thermal transfer printer, but no color was developed.
[0036]
[Table 3]

[0037]
(Ii) Abbreviations in the table are the same as those in Table 1.
[0038]
[Table 4]

[0039]
  From the results of the comparison between Example 11 and Comparative Examples 1, 4 and 6, it can be seen that the critical point of the mixing ratio of the color-decoloration controlling polymer and the electron-accepting phenol compound is appropriate. In addition, from the results of comparison between Examples 1, 4 and 9 and Comparative Examples 2, 3, 5 and 8, the critical point of the blending ratio of the color-decoloration controlling polymer and the electron donating color-forming compound is appropriate. I understand.Comparative Example 13, The glass transition temperature of the color-decoloration controlling polymer exceeds 60 ° C., so that incompatible change for decoloring of the polymer and the electron-accepting phenol compound hardly occurs, and the concentration at the time of decoloration is affected. is doingUnderstand. Further, the recording media obtained in Comparative Examples 7 and 10 hardly developed color. The recording media obtained in Comparative Examples 8 and 9 had a sufficient color density, but the density at the time of decoloration was large and was not suitable for practical use. The reason why the result other than the blending ratio was not satisfactory is that in Comparative Example 7, the long-chain saturated carboxylic acid is incompatible with the electron-donating color-forming compound and cannot react. Comparative Example 10, In 11 and 12, the functional group of the polymer that was supposed to be the color development / decoloration control polymer causes color development inhibition. This is because, in Comparative Example 9, the functional group in the color development / decoloration controlling polymer and the electron donating color-forming compound are in a state where they can always react.
[0040]
【The invention's effect】
The present invention has an advantage that even if coloring and erasing are repeated, the material can be used without deterioration, the image contrast is good, and desired recording and holding can be achieved.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the relationship between the temperature and color density of a reversible thermochromic recording material.
FIG. 2 is a DSC chart of a reversible thermochromic recording material in a colored state and a decolored state.
FIG. 3 is a DSC chart of a homogeneous material of CVL and styrene-butadiene copolymer heated to 60 ° C. and then cooled to room temperature.
FIG. 4 is a DSC chart of a homogeneous material of CVL and styrene-butadiene copolymer heated to 120 ° C. and then cooled to room temperature.
FIG. 5 is a DSC chart of a homogeneous material of stearyl gallate and styrene-butadiene copolymer heated to 70 ° C. and then cooled to room temperature.
FIG. 6 is an X-ray diffraction chart in a decolored state of a reversible thermochromic recording material.
FIG. 7 is an X-ray diffraction chart of stearyl gallate.
FIG. 8 is an X-ray diffraction chart of a styrene-butadiene copolymer.

Claims (9)

A reversible thermochromic recording material capable of repeating color development and color erasing by heating to a color development temperature and a color erasing temperature, comprising at least a. An electron-accepting phenol compound represented by the following general formula; and b. An electron donating color developing compound and c. Always compatible to the electron-donating coloring compound, it has a temperature range that does not compatible with the temperature range which is compatible to the electron-accepting phenol compound, the following glass transition temperature of the melting point of the electron-accepting phenol compound And comprising one or more color-decoloration controlling polymers selected from styrene-butadiene copolymer, styrene-isoprene-styrene copolymer, styrene-acrylic ester copolymer, butadiene polymer, styrene-ethylene-butadiene-styrene copolymer , The mixing ratio of the color-decoloration-controlling polymer: electron-accepting phenol compound: electron-donating color-forming compound is 1: 0.1 to 0.6: 0.01 to 0.09 in terms of weight ratio. A reversible thermochromic recording material characterized in that the temperature range is lower than the color development temperature range.

(Wherein R is an alkyl group of C ₃ or more)   The reversible thermochromic recording material according to claim 1, wherein the color-decoloration controlling polymer has a glass transition temperature of 60 ° C or lower. A reversible thermochromic recording medium comprising a support and a reversible thermochromic recording layer comprising the reversible thermochromic recording material according to claim 1 or 2 . The reversible thermochromic recording medium according to claim 3 , wherein an undercoat layer for improving adhesion is provided between the reversible thermochromic recording layer and the support. The reversible thermochromic recording medium according to claim 3 or 4 , wherein a protective layer is provided on the reversible thermochromic recording layer. The reversible thermochromic recording medium according to claim 5 , wherein the protective layer is made of a transparent polymer. The reversible thermochromic recording medium according to any one of claims 3 to 6 , comprising a colorant in the reversible thermochromic recording medium. Alone color consisting reversible thermochromic recording material or a plurality of colors of reversible thermochromic recording layer becomes formed in a predetermined character or a figure or a pattern on a support, any one of claims 3 to 7 2. A reversible thermochromic recording medium described in 1. The reversible thermochromic recording material made of a reversible thermochromic recording material is formed by laminating all or part of a reversible thermochromic recording layer of a single color or a plurality of colors on a support on which predetermined characters, figures or patterns are formed in advance. Item 8. The reversible thermochromic recording medium according to any one of Items 3 to 7 .

Images