JP4050624B2 - Thermal recording material - Google Patents

Description

【００１４】
また、該感熱記録層中に、補助増感剤として、一般式（２）で表される飽和脂肪酸モノアミドを含有することを特徴とする前記記載の感熱記録材料である。
【化４】

（式中、Ｒ₁は炭素数１１〜２１のアルキル基を示す。）
【００１５】
【発明の実施の形態】
本発明の内容を更に具体的に説明する。
支持体上に電子供与性である通常無色ないし淡色である染料前駆体と、加熱時反応して該染料前駆体を発色させる電子受容性化合物とを含有する感熱記録層を設けた感熱記録材料において、該感熱記録層中に該電子受容性化合物として、一般式（１）で表されるウレアウレタン化合物を用いることにより、他の電子受容性化合物を用いた場合と比較して、画像部の保存安定性が改善されるが、高い熱応答性、ならびに発色濃度は得られない。
しかし、本発明の感熱記録材料は、上記の一般式（１）で表されるウレアウレタン化合物に４−ヒドロキシ−４’−メチルジフェニルスルホンを併用することによって、該電子受容性化合物の画像部の保存安定性を損なうことなく、高い熱応答性、ならびに発色濃度が得られる。該電子受容性化合物と、４−ヒドロキシ−４’−メチルジフェニルスルホンの含有量質量比は、該電子受容性化合物１質量部に対して１〜２０質量部程度が好ましく、さらに好ましくは、５〜１０質量部程度である。
【００１６】
また、本発明の感熱記録材料は、該感熱記録層中に、補助増感剤として、上記の一般式（２）で表される飽和脂肪酸モノアミドを用いる。これによって、発色感度が著しく向上する。
【００１７】
本発明における感熱記録層に用いられる電子受容性化合物である上記の一般式（１）で表されるウレアウレタン化合物の具体的な例としては、４、４’−ビス［（４−メチル−３−フェノキシカルボニルアミノフェニル）ウレイド］ジフェニルスルホン、４、４’−ビス［（２−メチル−５−フェノキシカルボニルアミノフェニル）ウレイド］ジフェニルスルホン、［４−（２−メチル−５−フェノキシカルボニルアミノフェニル）−４’−（４−メチル−３−フェノキシカルボニルアミノフェニル）ウレイド］ジフェニルスルホンなどを挙げることができるが、本発明に係わるウレアウレタン化合物は、これに限定されるものではなく、また、これらのウレアウレタン化合物は必要に応じて単独、または２種以上併用して使用することができる。
【００１８】
本発明における感熱記録層に用いられる補助増感剤である上記一般式（２）で表される飽和脂肪酸モノアミドの具体的な例としては、ラウリン酸アミド、ミリスチン酸アミド、パルミチン酸アミド、ステアリン酸アミド、アラギン酸アミド、べへニン酸アミドなどを挙げることができるが、本発明に係わる飽和脂肪酸モノアミドは、これに限定されるものではなく、また、これらの飽和脂肪酸モノアミドは必要に応じて単独、または２種以上併用して使用することができる。
【００１９】
本発明の感熱記録材料は、一般に支持体上に電子供与性の通常無色ないし淡色の染料前駆体、及び本発明の電子受容性化合物である共反応体を主成分とし、これらをバインダーなどに分散した後、支持体上に塗工して感熱記録層を設け、熱ヘッド、熱ペン、レーザー光などで加熱することにより、染料前駆体、電子受容性化合物が瞬時反応し記録画像が得られるものである。上記感熱記録層には顔料、増感剤、バインダー、酸化防止剤、及びスティッキング防止剤などが必要に応じて添加される。
【００２０】
本発明の感熱記録材料に用いられる染料前駆体としては、一般に感圧記録材料、または感熱記録材料に用いられているものに代表されるが、これらに制限されることはない。
【００２１】
このような染料前駆体の具体的な例を挙げれば、次の通りである。
（１）トリアリールメタン系化合物：３，３−ビス（４−ジメチルアミノフェニル）−６−ジメチルアミノフタリド（クリスタルバイオレットラクトン）、３，３−ビス（４−ジメチルアミノフェニル）フタリド、３−（４−ジメ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−（４−ジメチルアミノフェニル）−３−（２−メチルインドール−３−イル）フタリド、３−（４−ジメチルアミノフェニル）−３−（２−フェニルインドール−３−イル）フタリド、３，３−ビス（１，２−ジメチルインドール−３−イル）−５−ジメチルアミノフタリド、３，３−ビス（１，２−ジメチルインドール−３−イル）−６−ジメチルアミノフタリド、３，３−ビス（９−エチルカルバゾール−３−イル）−５−ジメチルアミノフタリド、３，３−ビス（２−フェニルインドール−３−イル）−５−ジメチルアミノフタリド、３−（４−ジメチルアミノフェニル）−３−（１−メチルピロール−２−イル）−６−ジメチルアミノフタリドなど、
【００２２】
（２）ジフェニルメタン系化合物：４，４’−ビス（ジメチルアミノフェニル）ベンズヒドリルベンジルエーテル、Ｎ−クロロフェニルロイコオーラミン、Ｎ−２，４，５−トリクロロフェニルロイコオーラミンなど、
【００２３】
（３）キサンテン系化合物：ローダミンＢアニリノラクタム、ローダミンＢ−４−クロロアニリノラクタム、３−ジエチルアミノ−７−ジベンジルアミノフルオラン、３−ジエチルアミノ−７−オクチルアミノフルオラン、３−ジエチルアミノ−７−フェニルフルオラン、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−６−クロロ−７−メチルフルオラン、３−ジエチルアミノ−７−（３，４−ジクロロアニリノ）フルオラン、３−ジエチルアミノ−７−（２−クロロアニリノ）フルオラン、３−ジエチルアミノ−６−メチル−７−アニリノフルオラン、３−ジブチルアミノ−６−メチル−７−アニリノフルオラン、３−ジペンチルアミノ−６−メチル−７−アニリノフルオラン、３−ピペリジノ−６−メチル−７−アニリノフルオラン、３−（Ｎ−エチル−Ｎ−トリル）アミノ−６−メチル−７−フェネチルフルオラン、３−ジエチルアミノ−７−（４−ニトロアニリノ）フルオラン、３−（Ｎ−メチル−Ｎ−プロピル）アミノ−６−メチル−７−アニリノフルオラン、３−（Ｎ−エチル−Ｎ−イソアミル）アミノ−６−メチル−７−アニリノフルオラン、３−（Ｎ−メチル−Ｎ−シクロヘキシル）アミノ−６−メチル−７−アニリノフルオラン、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−アニリノフルオラン、３−ジエチルアミノ−６−メチル−７−（３−トルイジノ）フルオランなど、
【００２４】
（４）チアジン系化合物：ベンゾイルロイコメチレンブルー、４−ニトロベンゾイルロイコメチレンブルーなど、
【００２５】
（５）スピロ系化合物：３−メチルスピロジナフトピラン、３−エチルスピロジナフトピラン、３，３’−ジクロロスピロジナフトピラン、３−ベンジルスピロジナフトピラン、３−メチルナフト−（３−メトキシベンゾ）スピロピラン、３−プロピルスピロベンゾピランなどを挙げることができる。またこれらの染料前駆体は必要に応じて単独、もしくは２種以上混合して使用することができる。
【００２６】
本発明の感熱記録材料を構成する感熱記録層に含まれる発色成分の分散液は、発色成分を構成する化合物を乾式粉砕して分散媒中に分散する方法、または発色成分を構成する化合物を分散媒に混入し湿式粉砕する方法などにより得られる。
【００２７】
該分散液中の発色成分を構成する化合物の粒径は、通常７μｍ以下であり、０．１〜５μｍが好ましく、特に０．１〜２μｍの範囲が好ましい。平均粒子径が７μｍを超える場合には、光散乱が起こりやすく、感熱記録層の透明度が損なわれると共に、発色画像を得るためのエネルギーがより多く必要となる。
【００２８】
本発明では、本発明の効果を阻害しない限り、従来公知の増感剤を使用することが可能である。この場合、６０℃〜１８０℃の融点を有するものが好ましく、特に、８０℃〜１４０℃の融点を持つものがより好ましい。具体的な例を挙げれば、次の通りである。
Ｎ−ヒドロキシメチルステアリン酸アミド、Ｎ−ステアリルステアリン酸アミド、エチレンビスステアリン酸アミド、オレイン酸アミド、メチレンビス水添牛脂脂肪酸アミド、リシノール酸アミドなどの脂肪酸アミド類、パラフィンワックス、マイクロクリスタリンワックス、ポリエチレンワックス、カルナバワックスなどの合成、および天然ワックス類、Ｎ−ステアリル尿素などの脂肪族尿素化合物、ビス（４−メトキシフェニル）エーテル、２，２’−ビス（４−メトキシフェノキシ）ジエチルエーテル、１，２−ビス（３−メチルフェノキシ）エタン、１，２−ジフェノキシエタン、１，２−ビス（フェノキシメチル）ベンゼン、ナフチルエーテル誘導体、アントリルエーテル誘導体、脂肪族エーテルなどのエーテル化合物、アジピン酸ジフェニル、シュウ酸ジベンジル、シュウ酸ジ（４−クロルベンジル）、シュウ酸ジ（４−メチルベンジル）、炭酸ジフェニル、テレフタル酸ジメチル、テレフタル酸ジベンジル、ベンゼンスルホン酸フェニル、４−アセチルアセトフェノンなどのエステル化合物、３−ターフェニル、４−ベンジルビフェニル、４−アセチルビフェニル、４−アリルオキシビフェニルなどのビフェニル誘導体、ビス（４−アリルオキシフェニル）スルホン、アセト酢酸アニリド、４−メチルアセチルアニリド、脂肪酸アニリド類などの熱可融性化合物が挙げられるが、これらに限定されるものではなく、また必要に応じて単独、もしくは２種以上混合して使用することができる。
【００２９】
その他本発明の感熱記録材料の感熱記録層には、顔料として、ケイソウ土、タルク、カオリン、焼成カオリン、炭酸カルシウム 、炭酸マグネシウム、酸化チタン、酸化亜鉛、酸化ケイ素、水酸化アルミニウム、尿素−ホルマリン樹脂などの無機、ならびに有機顔料を用いることができる。その中でも特に、炭酸カルシウム、酸化ケイ素、水酸化アルミニウムが好ましく用いられる。
【００３０】
本発明の感熱記録材料に用いられる樹脂としては、デンプン類、ヒドロキシメチルセルロース、ヒドロキシエチルセルロース、メチルセルロース、エチルセルロース、カルボキシメチルセルロースなどのセルロース誘導体、ゼラチン、カゼイン、キトサン、ポリビニルアルコール、変性ポリビニルアルコール、アルギン酸ソーダ、ポリビニルピロリドン、ポリアクリルアミド、ポリアクリル酸ソーダ、アクリル酸アミド／アクリル酸エステル共重合体、アクリル酸アミド／アクリル酸エステル／メタクリル酸３元共重合体、ポリアクリル酸のアルカリ塩、ポリマレイン酸のアルカリ塩、スチレン／無水マレイン酸共重合体のアルカリ塩、エチレン／無水マレイン酸共重合体のアルカリ塩、イソブチレン／無水マレイン酸共重合体のアルカリ塩などの水溶性樹脂、ポリ酢酸ビニル、ポリウレタン、ポリアクリル酸エステル、スチレン−ブタジエン共重合体、アクリロニトリル／ブタジエン共重合体、アクリル酸メチル／ブタジエン共重合体、アクリロニトリル／ブタジエン／スチレン三元共重合体、ポリ酢酸ビニル、酢酸ビニル／アクリル酸エステル共重合体、エチレン／酢酸ビニル共重合体、ポリアクリル酸エステル、スチレン／アクリル酸エステル共重合体、ポリウレタンなどの水分散性樹脂が挙げられる。
【００３１】
その他の添加剤としては、加熱印字ヘッドの摩耗防止、またはスティッキング防止などの目的でステアリン酸亜鉛、ステアリン酸カルシウムなどの高級脂肪酸金属塩、パラフィン、酸化パラフィン、ポリエチレン、酸化ポリエチレンなどのワックス類、また、ジオクチルスルホコハク酸ナトリウムなどの分散剤、ベンゾフェノン系、ベンゾトリアゾール系などの紫外線吸収剤、さらにはアニオン性、ノニオン性の高分子量のものを含む界面活性剤、蛍光染料、消泡剤などを必要に応じて添加することができる。
【００３２】
感熱記録層の塗工量は、通常染料前駆体の塗工量で０．１〜２ｇ／ｍ²が適当である。上記の範囲でより優れた熱応答性と記録画像が得られる。
【００３３】
本発明の感熱記録材料は、必要に応じて支持体と感熱記録層の間に単層あるいは複数層の顔料あるいは樹脂からなるアンダーコート層を１層以上設けることができる。本発明における感熱記録材料がアンダーコート層を設けたものである場合、そのアンダーコート層の塗工量は、１〜３０ｇ／ｍ²が好ましく、３〜２０ｇ／ｍ²がより好ましい。
【００３４】
アンダーコート層の顔料としては、一般的には焼成カオリンが用いられるが、それ以外にもケイソウ土、タルク、カオリン、重質炭酸カルシウム、沈降炭酸カルシウム、炭酸マグネシウム、酸化亜鉛、酸化アルミニウム、水酸化アルミニウム、水酸化マグネシウム、二酸化チタン、硫酸バリウム、硫酸亜鉛、非晶質シリカ、非晶質ケイ酸カルシウム、コロイダルシリカ等の無機顔料、メラミン樹脂フィラー、尿素−ホルマリン樹脂フィラー、ポリエチレンパウダー、ナイロンパウダー、有機中空粒子、有機椀型粒子、貫通孔を有する有機粒子等の有機顔料を用いることができる。
【００３５】
アンダーコート層の樹脂としては、通常の塗工で用いられる種々の水溶性樹脂または水分散性樹脂を用いることができる。具体例についてはすでに述べた。
【００３６】
本発明の感熱記録材料は、感熱記録層を設けた後、さらにその上に水溶性樹脂または水分散性樹脂を主成分とする保護層を１層以上設けて、画像保存性を向上させることができる。保護層の乾燥塗工量は０．２〜１０ｇ／ｍ²が好ましく、０．５〜５ｇ／ｍ²がより好ましい。
【００３７】
保護層の水溶性樹脂または水分散性樹脂としては、従来公知の水溶性高分子または水分散性樹脂から適宜選択される。具体例についてはすでに述べた。また、電子線、紫外線により皮膜を形成する樹脂を使用してもよい。
【００３８】
保護層には、記録走行性、筆記性等を向上させる目的で、顔料を含有させることが可能である。顔料の具体例としては、ケイソウ土、タルク、カオリン、焼成カオリン、重質炭酸カルシウム、沈降炭酸カルシウム、炭酸マグネシウム、酸化亜鉛、酸化アルミニウム、水酸化アルミニウム、水酸化マグネシウム、二酸化チタン、硫酸バリウム、硫酸亜鉛、非晶質シリカ、非晶質ケイ酸カルシウム、コロイダルシリカ等の無機顔料、メラミン樹脂フィラー、尿素−ホルマリン樹脂フィラー、ポリエチレンパウダー、ナイロンパウダー等の有機顔料を使用することができる。
【００３９】
また、保護層には、ヘッド摩耗防止、スティッキング防止等記録走行性向上の目的から、ステアリン酸亜鉛、ステアリン酸カルシウム等の高級脂肪酸金属塩、ステアリン酸アミド等の高級脂肪酸アミド、パラフィン、ポリエチレンワックス、酸化ポリエチレン、カットワックスなどの滑剤が必要に応じて添加される。
【００４０】
さらに、感熱記録層が設けられている面と反対側の面に、電気的、光学的、磁気的に情報が記録可能な材料を含んでもよい。また、感熱記録層が設けられている面と反対側の面に、インクジェットプリンター適性を有するインク受理層や、ブロッキング防止、カール防止、帯電防止を目的としたバックコート層を設けることもできる。
【００４１】
感熱記録層、保護層、アンダーコート層、またはバックコート層の形成方法は、特に限定されるものではなく、従来公知の技術に従って形成することができる。具体的な例としては、エアナイフ塗工、ロッドブレード塗工、バー塗工、ブレード塗工、グラビア塗工、カーテン塗工、Ｅバー塗工などの方法により塗工液を塗工し、乾燥により感熱記録層、保護層、アンダーコート層、またはバックコート層を形成させることができる。
【００４２】
また、平版、凸版、フレキソ、グラビア、スクリーン、ホットメルトなどの方式による各種印刷機などによって各層を形成しても良い。
【００４３】
また、必要に応じて、アンダーコート層塗工後、感熱記録層塗工後、または保護層塗工後、スーパーカレンダー処理をし、画質を向上させることもできる。
【００４４】
なお、本発明に使用される支持体としては、紙が主として用いられるが、不織布、プラスチックフィルム、合成紙、金属箔など、あるいはこれらを組み合わせた複合シートを任意に用いることができる。
【００４５】
【実施例】
次に、本発明を実施例により、さらに詳細に説明する。ただし、これらに限定されるものではない。なお、以下に示す「部」、ならびに「％」は、特に断らない限りそれぞれ「質量部」、「質量％」を示し、塗工量は絶乾塗工量である。
【００４６】
実施例１
下塗り層用塗液の調製
焼成カオリン１００部、固形分濃度５０％のスチレン／ブタシエン系ラテックス２４部、固形分濃度２０％のリン酸エステル化澱粉３０部、および水２００部からなる組成物を混合攪拌して下塗り層用の塗液を得た。
【００４７】
感熱記録層用塗液の調製
＜分散液Ａ＞
３−ジブチルアミノ−６−メチル−７−アニリノフルオラン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が１μｍになるまで粉砕し分散液Ａを得た。
【００４８】
＜分散液Ｂ＞
４、４’−ビス［（４−メチル−３−フェノキシカルボニルアミノフェニル）ウレイド］ジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｃを得た。
【００４９】
＜分散液Ｃ＞
４−ヒドロキシ−４’−メチルジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｂを得た。
【００５０】
＜分散液Ｄ＞
１，２−ビス（３−メチルフェノキシ）エタン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が１μｍになるまで粉砕し分散液Ｄを得た。
【００５１】
＜分散液Ｅ＞
非晶質シリカ２００ｇを０．５％ポリアクリル酸ナトリウム塩水溶液８００ｇ中に分散し、ホモミキサーで１０分間撹拌し分散液Ｄを得た。
【００５２】
＜分散液Ｆ＞
水酸化アルミニウム２００ｇを０．５％ポリアクリル酸ナトリウム塩水溶液８００ｇ中に分散し、ホモミキサーで１０分間撹拌し分散液Ｄを得た。
【００５３】
上記の分散液を用い、各々の素材を下記に示す割合で混合し、感熱記録層用塗液濃度が１５％水溶液になるように添加水を加え、充分撹拌して感熱記録層用塗液を調製した。
分散液Ａ ４０部
分散液Ｂ １０部
分散液Ｃ ７０部
分散液Ｄ ２０部
分散液Ｅ ６０部
分散液Ｆ ６０部
４０％ステアリン酸亜鉛分散液 １０部
１０％完全鹸化ＰＶＡ水溶液 ４０部
【００５４】
感熱記録材料の作製
坪量６０ｇ／ｍ²の上質の中性紙の片面に、下塗り層用塗液の固形分塗抹量が１０ｇ／ｍ²、感熱記録層用塗液の固形分塗抹量が染料前駆体の塗工量で０．３ｇ／ｍ²となるように順次塗布乾燥して下塗り層、感熱記録層を形成して感熱記録材料を作製した。
【００５５】
実施例２
実施例１の感熱記録層用塗液の調製において、３０％ステアリン酸アミド分散液を３０部加えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００５６】
実施例３
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から１３部に変更し、分散液Ｃの添加量を７０部から６７部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００５７】
実施例４
実施例３の感熱記録層用塗液の調製において、３０％ステアリン酸アミド分散液を３０部加えた以外は、実施例３と同様にして感熱記録材料を作製した。
【００５８】
実施例５
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から８部に変更し、分散液Ｃの添加量を７０部から７２部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００５９】
実施例６
実施例５の感熱記録層用塗液の調製において、３０％ステアリン酸アミド分散液を３０部加えた以外は、実施例５と同様にして感熱記録材料を作製した。
【００６０】
実施例７
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から４部に変更し、分散液Ｃの添加量を７０部から７６部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００６１】
実施例８
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から４０部に変更し、さらに分散液Ｃの添加量を７０部から４０部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００６２】
実施例９
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から６０部に変更し、さらに分散液Ｃの添加量を７０部から２０部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００６３】
実施例１０
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から２部に変更し、さらに分散液Ｃの添加量を７０部から７８部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００６４】
比較例１
実施例１の感熱記録層用塗液の調製において、分散液Ｂの添加量を１０部から８０部に変更し、かつ、分散液Ｃを加えなかった以外は、実施例１と同様にして感熱記録材料を作製した。
【００６５】
比較例２
実施例１の感熱記録層用塗液の調製において、分散液Ｂを加えず、かつ、分散液Ｃの添加量を７０部から８０部に変更した以外は、実施例１と同様にして感熱記録材料を作製した。
【００６６】
比較例３
＜分散液Ｇ＞
２、２−ビス（４−ヒドロキシフェニル）プロパン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｇを得た。
【００６７】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｇに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００６８】
比較例４
＜分散液Ｈ＞
４−ヒドロキシ−４’−イソプロポキシジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｈを得た。
【００６９】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｈに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００７０】
比較例５
＜分散液Ｉ＞
ビス（３−アリル−４−ヒドロキシフェニル）スルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｉを得た。
【００７１】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｉに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００７２】
比較例６
＜分散液Ｊ＞
２、４’−ジヒドロキシジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｊを得た。
【００７３】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｊに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００７４】
比較例７
＜分散液Ｋ＞
４、４’−ジヒドロキシジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｋを得た。
【００７５】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｋに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００７６】
比較例８
＜分散液Ｌ＞
４、４’−ジクロロジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｌを得た。
【００７７】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｌに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００７８】
比較例９
＜分散液Ｍ＞
４−ヒドロキシ−４’−プロポキシジフェニルスルホン２００ｇを１０％スルホン基変性ポリビニルアルコール水溶液２００ｇ、水６００ｇの混合物中に分散し、ビーズミルで平均粒子径が０．７μｍになるまで粉砕し分散液Ｍを得た。
【００７９】
実施例１の感熱記録層用塗液の調製において、分散液Ｃを分散液Ｍに置き換えた以外は、実施例１と同様にして感熱記録材料を作製した。
【００８０】
以上の実施例１〜１０、比較例１〜９で作製した感熱記録材料を感熱記録層塗工面のベック平滑度が３００〜８００秒になるようにカレンダー処理した後、以下の評価に供した。評価結果を表１に示す。
【００８１】
［熱応答性］
大倉電機製ファクシミリ試験機ＴＨ−ＰＭＤを用いて印字テストを行った。ドット密度８ドット／ｍｍ、ヘッド抵抗１６８５Ωのサーマルヘッドを使用し、ヘッド電圧２１Ｖ、パルス幅１．０ｍｓｅｃで通電して印字し、発色濃度をマクベスＲＤ−９１８型反射濃度計（ビジュアルフィルター）で測定した。記録部は数値の大きい方が熱応答性に優れる。また、地肌部は数値が小さいほど地肌カブリが少ないことを示す。
【００８２】
画像部の保存特性の評価は、耐可塑剤性試験、耐水性試験ならびに耐酒性試験で行った。
【００８３】
［耐可塑剤性試験］
熱応答性特性の評価で用いたパルス幅１．０ｍｓｅｃで印字した印字画像と、未印字の地肌に軟質塩ビシートを密着させ、４０℃の条件下に２４時間保存した後の濃度をマクベスＲＤ−９１８型反射濃度計（ビジュアルフィルター）で測定した。記録部の数値が大きいほど耐可塑剤画像保存性に優れる。
【００８４】
［耐水性試験］
熱応答性特性の評価で用いたパルス幅１．０ｍｓｅｃで印字した感熱記録材料を２０℃の水道水に２４時間浸漬した後、印字画像の濃度をマクベスＲＤ−９１８型反射濃度計（ビジュアルフィルター）で測定した。記録画像の数値が大きいほど耐水画像保存性に優れる。
【００８５】
［耐酒性試験］
熱応答性特性の評価で用いたパルス幅１．０ｍｓｅｃで印字した感熱記録材料を２０℃の日本酒に２４時間浸漬した後、印字画像の濃度をマクベスＲＤ−９１８型反射濃度計（ビジュアルフィルター）で測定した。記録画像の数値が大きいほど耐酒画像保存性に優れる。
【００８６】
【表１】

【００８７】
上記表１から明らかなごとく、支持体上に電子供与性の通常無色ないし淡色の染料前駆体と、加熱時反応して該染料前駆体を発色させる電子受容性化合物とを含有する感熱記録層を設けた感熱記録材料において、該感熱記録層中に該電子受容性化合物として、一般式（１）で表されるウレアウレタン化合物を含有する実施例１〜１０は、該電子受容性化合物を含有しない比較例２と比較して、画像部の保存安定性が著しく向上しているのが判る。
【００８８】
また、実施例１〜１０は、本発明における感熱記録層に用いられる４−ヒドロキシ−４’−メチルジフェニルスルホンを含有することから、４−ヒドロキシ−４’−メチルジフェニルスルホンを含有しない比較例１と比べて熱応答性が著しく向上しているのが判る。
【００８９】
また、支持体上に電子供与性の通常無色ないし淡色の染料前駆体と、加熱時反応して該染料前駆体を発色させる電子受容性化合物とを含有する感熱記録層を設けた感熱記録材料において、該感熱記録層中に該電子受容性化合物として、一般式（１）で表されるウレアウレタン化合物に加えて、４−ヒドロキシ−４’−メチルジフェニルスルホン以外の他の電子受容性化合物を含有する比較例３〜９は、実施例１〜１０と比較して、熱応答性は遜色ない程に優れるが、画像部の保存安定性が実施例１〜１０より劣る。
【００９０】
【発明の効果】
支持体上に電子受容性の通常無色ないし淡色の染料前駆体と、加熱時反応して該染料前駆体を発色させる電子受容性化合物とを含有する感熱記録層を設けた感熱記録材料において、感熱記録層中に電子受容性化合物として、一般式（１）で表されるウレアウレタン化合物を用い、該電子受容性化合物と４−ヒドロキシ−４’−メチルジフェニルスルホンを併用することで、該電子受容性化合物の画像部の保存安定性を損なうことなく、熱応答性、ならびに発色濃度が改善される。該電子受容性化合物と、４−ヒドロキシ−４’−メチルジフェニルスルホンの含有量質量比は、該電子受容性化合物１質量部に対して１〜２０質量部程度が好ましく、さらに好ましくは、５〜１０質量部程度である。
また、本発明の感熱記録材料は、該感熱記録層中に、補助増感剤として、一般式（２）で表される飽和脂肪酸モノアミドを用いることによって、発色感度が著しく向上する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-sensitive recording material, and relates to a heat-sensitive recording material excellent in recording sensitivity, image storage stability, and background fog resistance.
[0002]
[Prior art]
A heat-sensitive recording material is generally a support provided with a heat-sensitive recording layer comprising, as a main component, an electron-donating usually colorless or light-colored dye precursor and an electron-accepting developer. By heating with a pen, laser light, etc., the dye precursor and the developer react instantaneously to obtain a recorded image. A recording device for recording on such a heat-sensitive recording material is advantageous in that it is relatively inexpensive, compact, easy to maintain, and free from noise. It is used in a wide range of fields as a recording medium for facsimiles, printers, computer terminals, labels, ticket vending machines, and the like.
[0003]
Particularly in recent years, heat-sensitive recording materials have also been used for financial-related recording papers such as receipts for gas, water, electricity charges, etc., ATM usage statements for financial institutions, and various receipts.
[0004]
As the uses and demands of heat-sensitive recording materials expand in a variety of ways, high thermal responsiveness and storage stability of image portions have been demanded.
[0005]
However, the heat-sensitive recording material obtains a recorded image by heating. When high sensitivity, that is, thermal responsiveness is realized, the recorded image deteriorates when exposed to high temperature, high humidity, or both for a long time. Or the discoloration of the uncolored portion, that is, the background fogging becomes large. Due to the deterioration of the recorded image and the background fogging, the contrast between the image portion and the background is lost. Therefore, it is desired to develop a heat-sensitive recording material having high thermal responsiveness, color density, little background fogging, and excellent image storage stability.
[0006]
As a means for obtaining a heat-sensitive recording material having high thermal responsiveness and color development density with little background fogging and excellent image storage stability, a urea urethane compound is used as an electron-accepting compound in the heat-sensitive recording layer. In addition, various electron accepting compounds and sensitizers are used in combination, and heat-sensitive recording materials, such as diphenylsulfone derivatives (see, for example, Patent Document 1), diphenylsulfonic acid derivatives (for example, Patent Document 2, 3), a sulfonamide derivative or a combination of a diphenylsulfone derivative and a diphenylsulfonic acid derivative (for example, see Patent Document 4).
[0007]
However, the urea urethane compound described in the publication has a problem of low color sensitivity even when used alone as an electron-accepting compound or in combination with other electron-accepting compounds. Is done.
[0008]
In order to improve the thermal responsiveness of the thermosensitive recording material, it contains, as main components, an electron-donating usually colorless or light-colored dye precursor and an electron-accepting compound that reacts when heated to develop the dye precursor. A heat-sensitive recording material provided with a heat-sensitive recording layer, wherein the heat-sensitive recording layer contains 4-hydroxy-4′-methyldiphenylsulfone as the electron-accepting compound (for example, Patent Document 5). Although a high thermal response and color density can be obtained, a thermosensitive recording material excellent in storage stability of the image area has not yet been obtained.
[0009]
In order to improve the thermal responsiveness of the heat-sensitive recording material, various sensitizers are added as necessary in addition to the diphenyl sulfone derivative and the sulfonamide derivative. When the sensitizer is melted by the transferred thermal energy, it has the effect of accelerating the color reaction by dissolving or encapsulating the nearby dye precursor and the electron accepting compound. Increasing the thermal responsiveness or compatibility with the dye precursor and the electron accepting compound is one means for increasing the sensitivity of the thermosensitive recording material.
[0010]
As this technique, waxes (for example, refer to Patent Document 6), nitrogen-containing compounds, carboxylic acid esters and the like (for example, refer to Patent Document 7), naphthol derivatives (for example, refer to Patent Document 8), naphthoic acid derivatives ( For example, refer to Patent Document 9), benzoic acid ester derivatives (for example, refer to Patent Document 10), parabenzylbiphenyl (for example, refer to Patent Document 11), and diphenoxyethanes (for example, refer to Patent Document 12). Examples of addition are disclosed. However, heat-sensitive recording materials produced by these disclosed methods are still insufficient in color density and thermal response at low temperatures.
[0011]
[Patent Document 1]
JP 2001-1646 A
[Patent Document 2]
JP 2001-341424 A
[Patent Document 3]
JP 2002-178645 A
[Patent Document 4]
JP 2002-178646 A
[Patent Document 5]
Japanese Unexamined Patent Publication No. 57-210886
[Patent Document 6]
Japanese Patent Laid-Open No. 48-19231
[Patent Document 7]
JP 49-34842 A
[Patent Document 8]
JP-A-57-64593
[Patent Document 9]
JP 57-64592 A
[Patent Document 10]
JP-A-57-148688
[Patent Document 11]
JP 60-122193 A
[Patent Document 12]
JP-A-60-56588
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a heat-sensitive recording material excellent in color density, storage stability, and background fog resistance of a recording portion.
[0013]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have invented the heat-sensitive recording material of the present invention that can solve the above-mentioned problems.
That is, the heat-sensitive recording material of the present invention comprises a heat-sensitive recording layer containing, as main components, an electron-donating usually colorless or light-colored dye precursor and an electron-accepting compound that reacts when heated to develop the color of the dye precursor. In the heat-sensitive recording material, the urea-containing urethane compound represented by the general formula (1) is contained as the electron-accepting compound in the heat-sensitive recording layer, and 4-hydroxy-4′-methyldiphenyl sulfone is contained. It is a heat-sensitive recording material characterized by containing.
[Chemical Formula 3]

[0014]
The thermosensitive recording material according to the above, wherein the thermosensitive recording layer contains a saturated fatty acid monoamide represented by the general formula (2) as an auxiliary sensitizer.
[Formula 4]

(Wherein R₁Represents an alkyl group having 11 to 21 carbon atoms. )
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The contents of the present invention will be described more specifically.
In a heat-sensitive recording material provided with a heat-sensitive recording layer comprising, on a support, an electron-donating dye precursor that is usually colorless or light-colored, and an electron-accepting compound that reacts when heated to develop a color of the dye precursor By using the urea urethane compound represented by the general formula (1) as the electron-accepting compound in the thermosensitive recording layer, the image area can be preserved as compared with the case of using another electron-accepting compound. Although stability is improved, high thermal responsiveness and color density cannot be obtained.
However, the heat-sensitive recording material of the present invention uses 4-hydroxy-4′-methyldiphenyl sulfone in combination with the urea urethane compound represented by the above general formula (1), so that the image portion of the electron-accepting compound can be used. High thermal response and color density can be obtained without impairing storage stability. The content mass ratio of the electron accepting compound and 4-hydroxy-4′-methyldiphenyl sulfone is preferably about 1 to 20 parts by mass, more preferably 5 to 5 parts by mass with respect to 1 part by mass of the electron accepting compound. About 10 parts by mass.
[0016]
The heat-sensitive recording material of the present invention uses a saturated fatty acid monoamide represented by the above general formula (2) as an auxiliary sensitizer in the heat-sensitive recording layer. Thereby, the color development sensitivity is remarkably improved.
[0017]
Specific examples of the urea urethane compound represented by the above general formula (1), which is an electron accepting compound used in the heat-sensitive recording layer in the present invention, include 4,4′-bis [(4-methyl-3 -Phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4,4'-bis [(2-methyl-5-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, [4- (2-methyl-5-phenoxycarbonylaminophenyl) -4 '-(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, and the like, but the urea urethane compound according to the present invention is not limited thereto, and these Urea urethane compounds can be used alone or in combination of two or more as required. That.
[0018]
Specific examples of the saturated fatty acid monoamide represented by the general formula (2), which is an auxiliary sensitizer used in the heat-sensitive recording layer in the present invention, include lauric acid amide, myristic acid amide, palmitic acid amide, and stearic acid. Examples thereof include amides, araginic acid amides and behenic acid amides, but the saturated fatty acid monoamides according to the present invention are not limited thereto, and these saturated fatty acid monoamides may be used alone as necessary. Or two or more types can be used in combination.
[0019]
The heat-sensitive recording material of the present invention generally comprises, on a support, an electron-donating usually colorless or light-colored dye precursor and a coreactant that is the electron-accepting compound of the present invention as a main component, and these are dispersed in a binder or the like. After that, a thermal recording layer is provided by coating on a support and heated with a thermal head, thermal pen, laser beam, etc., so that a dye precursor and an electron accepting compound react instantaneously to obtain a recorded image It is. A pigment, a sensitizer, a binder, an antioxidant, an anti-sticking agent, and the like are added to the heat-sensitive recording layer as necessary.
[0020]
The dye precursors used in the heat-sensitive recording material of the present invention are typically represented by pressure-sensitive recording materials or those used in heat-sensitive recording materials, but are not limited thereto.
[0021]
Specific examples of such dye precursors are as follows.
(1) Triarylmethane compounds: 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (4-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (4-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (4-Dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3 -Bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl)- -Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrol-2-yl ) -6-dimethylaminophthalide, etc.
[0022]
(2) Diphenylmethane compounds: 4,4'-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine, etc.
[0023]
(3) Xanthene compounds: rhodamine B anilinolactam, rhodamine B-4-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino- 7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino -7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl- 7-anilinofluorane, 3-piperidino-6-methyl-7-a Linofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3- (N-methyl-N-propyl) amino -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6 -Methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (3-toluidino ) Fluoran etc.
[0024]
(4) Thiazine compounds: benzoyl leucomethylene blue, 4-nitrobenzoyl leucomethylene blue, etc.
[0025]
(5) Spiro compounds: 3-methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3′-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphthylpyrans (3-methoxy) Benzo) spiropyran, 3-propyl spirobenzopyran and the like. These dye precursors can be used alone or in admixture of two or more as required.
[0026]
The color developing component dispersion contained in the thermosensitive recording layer constituting the thermosensitive recording material of the present invention is a method of dry pulverizing the compound constituting the color developing component and dispersing it in a dispersion medium, or dispersing the compound constituting the color developing component. It is obtained by a method of mixing in a medium and performing wet grinding.
[0027]
The particle size of the compound constituting the color forming component in the dispersion is usually 7 μm or less, preferably 0.1 to 5 μm, particularly preferably 0.1 to 2 μm. When the average particle diameter exceeds 7 μm, light scattering tends to occur, the transparency of the heat-sensitive recording layer is impaired, and more energy is required to obtain a color image.
[0028]
In the present invention, conventionally known sensitizers can be used as long as the effects of the present invention are not impaired. In this case, those having a melting point of 60 ° C. to 180 ° C. are preferred, and those having a melting point of 80 ° C. to 140 ° C. are particularly preferred. A specific example is as follows.
Fatty acid amides such as N-hydroxymethyl stearic acid amide, N-stearyl stearic acid amide, ethylene bis stearic acid amide, oleic acid amide, methylene bis hydrogenated tallow fatty acid amide, ricinoleic acid amide, paraffin wax, microcrystalline wax, polyethylene wax , Synthesis of carnauba wax and the like, and natural waxes, aliphatic urea compounds such as N-stearyl urea, bis (4-methoxyphenyl) ether, 2,2′-bis (4-methoxyphenoxy) diethyl ether, 1,2 -Ether compounds such as bis (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1,2-bis (phenoxymethyl) benzene, naphthyl ether derivatives, anthryl ether derivatives, aliphatic ethers, adipine Ester compounds such as diphenyl, dibenzyl oxalate, di (4-chlorobenzyl) oxalate, di (4-methylbenzyl) oxalate, diphenyl carbonate, dimethyl terephthalate, dibenzyl terephthalate, phenyl benzenesulfonate, 4-acetylacetophenone Biphenyl derivatives such as 3-terphenyl, 4-benzylbiphenyl, 4-acetylbiphenyl, 4-allyloxybiphenyl, bis (4-allyloxyphenyl) sulfone, acetoacetanilide, 4-methylacetylanilide, fatty acid anilides, etc. However, the present invention is not limited to these, and may be used alone or in combination of two or more as required.
[0029]
Other In the heat-sensitive recording layer of the heat-sensitive recording material of the present invention, as a pigment, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin Inorganic as well as organic pigments can be used. Of these, calcium carbonate, silicon oxide, and aluminum hydroxide are particularly preferably used.
[0030]
Examples of the resin used in the heat-sensitive recording material of the present invention include starches, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, chitosan, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinyl Pyrrolidone, polyacrylamide, polyacrylic acid soda, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, Alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, alkali salt of isobutylene / maleic anhydride copolymer Any water-soluble resin, polyvinyl acetate, polyurethane, polyacrylate, styrene-butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene terpolymer, Examples thereof include water-dispersible resins such as polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic acid ester, styrene / acrylic acid ester copolymer, and polyurethane.
[0031]
Other additives include higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene and polyethylene oxide for the purpose of preventing wear of the heated print head or preventing sticking, Dispersants such as sodium dioctylsulfosuccinate, UV absorbers such as benzophenone and benzotriazole, and surfactants including anionic and nonionic high molecular weight, fluorescent dyes, antifoaming agents, etc. as required Can be added.
[0032]
The coating amount of the thermosensitive recording layer is usually 0.1 to 2 g / m in terms of the coating amount of the dye precursor.²Is appropriate. Within the above range, better thermal responsiveness and recorded images can be obtained.
[0033]
In the heat-sensitive recording material of the present invention, if necessary, one or more undercoat layers made of a single layer or a plurality of layers of pigments or resins can be provided between the support and the heat-sensitive recording layer. When the heat-sensitive recording material in the present invention is provided with an undercoat layer, the coating amount of the undercoat layer is 1 to 30 g / m.²Is preferably 3 to 20 g / m.²Is more preferable.
[0034]
In general, calcined kaolin is used as a pigment for the undercoat layer, but diatomaceous earth, talc, kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, and hydroxide are also used. Inorganic pigments such as aluminum, magnesium hydroxide, titanium dioxide, barium sulfate, zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, melamine resin filler, urea-formalin resin filler, polyethylene powder, nylon powder, Organic pigments such as organic hollow particles, organic cage particles, and organic particles having through-holes can be used.
[0035]
As the resin for the undercoat layer, various water-soluble resins or water-dispersible resins used in normal coating can be used. Specific examples have already been mentioned.
[0036]
In the heat-sensitive recording material of the present invention, after providing a heat-sensitive recording layer, one or more protective layers mainly composed of a water-soluble resin or a water-dispersible resin are further provided thereon to improve image storage stability. it can. The dry coating amount of the protective layer is 0.2 to 10 g / m.²Is preferably 0.5 to 5 g / m²Is more preferable.
[0037]
The water-soluble resin or water-dispersible resin for the protective layer is appropriately selected from conventionally known water-soluble polymers or water-dispersible resins. Specific examples have already been mentioned. Moreover, you may use resin which forms a film | membrane with an electron beam and an ultraviolet-ray.
[0038]
The protective layer can contain a pigment for the purpose of improving the recording running property, writing property and the like. Specific examples of pigments include diatomaceous earth, talc, kaolin, calcined kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, sulfuric acid Inorganic pigments such as zinc, amorphous silica, amorphous calcium silicate, and colloidal silica, and organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder, and nylon powder can be used.
[0039]
The protective layer has a higher fatty acid metal salt such as zinc stearate and calcium stearate, a higher fatty acid amide such as stearic acid amide, paraffin, polyethylene wax, oxidation for the purpose of improving the recording running properties such as head wear prevention and sticking prevention. A lubricant such as polyethylene and cut wax is added as necessary.
[0040]
Further, the surface opposite to the surface on which the thermosensitive recording layer is provided may include a material capable of recording information electrically, optically, and magnetically. Further, an ink receiving layer having ink jet printer suitability and a backcoat layer for preventing blocking, curling and antistatic can be provided on the surface opposite to the surface on which the heat-sensitive recording layer is provided.
[0041]
The method for forming the heat-sensitive recording layer, protective layer, undercoat layer, or backcoat layer is not particularly limited, and can be formed according to a conventionally known technique. As specific examples, the coating liquid is applied by a method such as air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, E-bar coating, etc. A thermosensitive recording layer, a protective layer, an undercoat layer, or a backcoat layer can be formed.
[0042]
In addition, each layer may be formed by various printing machines such as a lithographic plate, a relief plate, a flexo, a gravure, a screen, and a hot melt.
[0043]
Further, if necessary, after applying the undercoat layer, after applying the heat-sensitive recording layer, or after applying the protective layer, a super calender treatment can be performed to improve the image quality.
[0044]
As the support used in the present invention, paper is mainly used. However, a nonwoven fabric, a plastic film, a synthetic paper, a metal foil, or a composite sheet obtained by combining these can be arbitrarily used.
[0045]
【Example】
Next, the present invention will be described in more detail with reference to examples. However, it is not limited to these. The “parts” and “%” shown below represent “parts by mass” and “mass%”, respectively, unless otherwise specified, and the coating amount is an absolutely dry coating amount.
[0046]
Example 1
Preparation of coating solution for undercoat layer
A composition comprising 100 parts of calcined kaolin, 24 parts of a 50% solid content styrene / butaciene latex, 30 parts of a phosphate esterified starch with a solid content concentration of 20%, and 200 parts of water is mixed and stirred for the undercoat layer. A coating solution was obtained.
[0047]
Preparation of thermal recording layer coating liquid
<Dispersion A>
200 g of 3-dibutylamino-6-methyl-7-anilinofluorane is dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size becomes 1 μm. A was obtained.
[0048]
<Dispersion B>
200 g of 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone was dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was measured by a bead mill. Dispersion C was obtained by pulverizing to 0.7 μm.
[0049]
<Dispersion C>
200 g of 4-hydroxy-4′-methyldiphenylsulfone is dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size becomes 0.7 μm to obtain a dispersion B. It was.
[0050]
<Dispersion D>
Dispersion D was obtained by dispersing 200 g of 1,2-bis (3-methylphenoxy) ethane in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a bead mill until the average particle size became 1 μm. It was.
[0051]
<Dispersion E>
200 g of amorphous silica was dispersed in 800 g of 0.5% sodium polyacrylate aqueous solution and stirred for 10 minutes with a homomixer to obtain dispersion D.
[0052]
<Dispersion F>
200 g of aluminum hydroxide was dispersed in 800 g of a 0.5% sodium polyacrylate aqueous solution and stirred with a homomixer for 10 minutes to obtain dispersion D.
[0053]
  Using the above dispersion, mix each material in the ratio shown below,Recording layer coating solutionAdd the added water so that the concentration is 15% aqueous solution, stir well and heat sensitive recording layerforA coating solution was prepared.
Dispersion A 40 parts
Dispersion B 10 parts
Dispersion C 70 parts
Dispersion D 20 parts
Dispersion E 60 parts
Dispersion F 60 parts
10 parts of 40% zinc stearate dispersion
40 parts of 10% fully saponified PVA aqueous solution
[0054]
Production of thermal recording materials
Basis weight 60g / m²The solid coating amount of the coating solution for the undercoat layer is 10 g / m on one side of high-quality neutral paper²The solid coating amount of the thermal recording layer coating solution is 0.3 g / m in terms of the coating amount of the dye precursor.²In order to form a heat-sensitive recording material, an undercoat layer and a heat-sensitive recording layer were formed.
[0055]
Example 2
A thermosensitive recording material was prepared in the same manner as in Example 1 except that 30 parts of a 30% stearamide dispersion was added in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0056]
Example 3
In the preparation of the thermosensitive recording layer coating liquid of Example 1, the amount of dispersion B added was changed from 10 parts to 13 parts, and the amount of dispersion C added was changed from 70 parts to 67 parts. In the same manner as in No. 1, a heat-sensitive recording material was produced.
[0057]
Example 4
A thermosensitive recording material was prepared in the same manner as in Example 3, except that 30 parts of a 30% stearamide dispersion was added in the preparation of the thermosensitive recording layer coating liquid of Example 3.
[0058]
Example 5
In the preparation of the heat-sensitive recording layer coating solution of Example 1, the addition amount of dispersion B was changed from 10 parts to 8 parts, and the addition amount of dispersion liquid C was changed from 70 parts to 72 parts. In the same manner as in No. 1, a heat-sensitive recording material was produced.
[0059]
Example 6
A thermosensitive recording material was produced in the same manner as in Example 5 except that 30 parts of 30% stearamide dispersion was added in the preparation of the thermosensitive recording layer coating liquid of Example 5.
[0060]
Example 7
In the preparation of the heat-sensitive recording layer coating solution of Example 1, the amount of dispersion B added was changed from 10 parts to 4 parts, and the amount of dispersion C added was changed from 70 parts to 76 parts. In the same manner as in No. 1, a heat-sensitive recording material was produced.
[0061]
Example 8
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the amount of dispersion B added was changed from 10 parts to 40 parts, and the amount of dispersion C added was changed from 70 parts to 40 parts. A thermosensitive recording material was prepared in the same manner as in Example 1.
[0062]
Example 9
In the preparation of the thermosensitive recording layer coating liquid of Example 1, except that the amount of dispersion B added was changed from 10 parts to 60 parts and the amount of dispersion C added was changed from 70 parts to 20 parts. A thermosensitive recording material was prepared in the same manner as in Example 1.
[0063]
Example 10
In the preparation of the thermal recording layer coating liquid of Example 1, the amount of dispersion B added was changed from 10 parts to 2 parts, and the amount of dispersion C added was changed from 70 parts to 78 parts. A thermosensitive recording material was prepared in the same manner as in Example 1.
[0064]
Comparative Example 1
In the preparation of the thermal recording layer coating liquid of Example 1, the thermal sensitivity was changed in the same manner as in Example 1 except that the amount of dispersion B was changed from 10 parts to 80 parts and no dispersion C was added. A recording material was prepared.
[0065]
Comparative Example 2
In the preparation of the thermal recording layer coating liquid of Example 1, thermal recording was performed in the same manner as in Example 1 except that Dispersion B was not added and the amount of dispersion C was changed from 70 parts to 80 parts. The material was made.
[0066]
Comparative Example 3
<Dispersion G>
Dispersion G was prepared by dispersing 200 g of 2,2-bis (4-hydroxyphenyl) propane in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water and pulverizing with a bead mill until the average particle size became 0.7 μm. Got.
[0067]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion G in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0068]
Comparative Example 4
<Dispersion H>
Disperse the dispersion H by dispersing 200 g of 4-hydroxy-4′-isopropoxydiphenylsulfone in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a bead mill until the average particle size becomes 0.7 μm. Obtained.
[0069]
A thermosensitive recording material was prepared in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion H in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0070]
Comparative Example 5
<Dispersion I>
Dispersion I was obtained by dispersing 200 g of bis (3-allyl-4-hydroxyphenyl) sulfone in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a bead mill until the average particle size became 0.7 μm. Got.
[0071]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion I in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0072]
Comparative Example 6
<Dispersion J>
200 g of 2,4′-dihydroxydiphenylsulfone was dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size became 0.7 μm to obtain a dispersion J.
[0073]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion J in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0074]
Comparative Example 7
<Dispersion K>
200 g of 4,4'-dihydroxydiphenylsulfone was dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size became 0.7 μm, whereby dispersion K was obtained.
[0075]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion K in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0076]
Comparative Example 8
<Dispersion L>
200 g of 4,4′-dichlorodiphenylsulfone was dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size became 0.7 μm, whereby dispersion L was obtained.
[0077]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion L in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0078]
Comparative Example 9
<Dispersion M>
200 g of 4-hydroxy-4′-propoxydiphenylsulfone is dispersed in a mixture of 200 g of a 10% sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size becomes 0.7 μm to obtain a dispersion M. It was.
[0079]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the dispersion C was replaced with the dispersion M in the preparation of the thermosensitive recording layer coating liquid of Example 1.
[0080]
The heat-sensitive recording materials prepared in Examples 1 to 10 and Comparative Examples 1 to 9 were calendered so that the Beck smoothness of the heat-sensitive recording layer coated surface was 300 to 800 seconds, and then subjected to the following evaluation. The evaluation results are shown in Table 1.
[0081]
[Thermal response]
  A printing test was performed using a facsimile testing machine TH-PMD manufactured by Okura Electric. Using a thermal head with a dot density of 8 dots / mm and a head resistance of 1685 Ω, printing was carried out with a head voltage of 21 V and a pulse width of 1.0 msec, and the color density was measured with a Macbeth RD-918 type reflection densitometer (visual filter). did.The recording partThe larger the value, the better the thermal response.The background portion indicates that the smaller the numerical value, the less the background fog.
[0082]
The storage characteristics of the image area were evaluated by a plasticizer resistance test, a water resistance test, and a liquor resistance test.
[0083]
[Plasticizer resistance test]
  The printed image printed with a pulse width of 1.0 msec used in the evaluation of the thermal response characteristics and the soft PVC sheet in close contact with the unprinted ground, and the concentration after storing for 24 hours under the condition of 40 ° C., Macbeth RD- Measured with a 918 reflection densitometer (visual filter). RecordPartThe larger the value, the better the plasticizer image storage stability.Ru.
[0084]
[Water resistance test]
A thermal recording material printed with a pulse width of 1.0 msec used in the evaluation of thermal response characteristics was immersed in tap water at 20 ° C. for 24 hours, and then the density of the printed image was measured by Macbeth RD-918 reflection densitometer (visual filter). Measured with The larger the numerical value of the recorded image, the better the water-resistant image storage stability.
[0085]
[Liquor resistance test]
After the thermal recording material printed with a pulse width of 1.0 msec used in the evaluation of thermal response characteristics was immersed in sake at 20 ° C. for 24 hours, the density of the printed image was measured with a Macbeth RD-918 reflection densitometer (visual filter). It was measured. The larger the numerical value of the recorded image, the better the storage stability of the liquor image.
[0086]
[Table 1]

[0087]
As is apparent from Table 1 above, a thermosensitive recording layer containing an electron donating usually colorless or light color dye precursor on a support and an electron accepting compound that reacts when heated to cause the dye precursor to develop a color. In the provided thermosensitive recording material, Examples 1 to 10 containing the urea urethane compound represented by the general formula (1) as the electron accepting compound in the thermosensitive recording layer do not contain the electron accepting compound. It can be seen that the storage stability of the image area is remarkably improved as compared with Comparative Example 2.
[0088]
Moreover, since Examples 1-10 contain 4-hydroxy-4'-methyldiphenyl sulfone used for the heat-sensitive recording layer in the present invention, Comparative Example 1 does not contain 4-hydroxy-4'-methyldiphenyl sulfone. It can be seen that the thermal responsiveness is remarkably improved as compared with FIG.
[0089]
Further, in a thermosensitive recording material provided with a thermosensitive recording layer containing an electron-donating usually colorless or light-colored dye precursor on a support and an electron-accepting compound that reacts upon heating to develop the dye precursor. In addition to the urea urethane compound represented by the general formula (1), the electron-sensitive compound other than 4-hydroxy-4′-methyldiphenylsulfone is contained in the heat-sensitive recording layer as the electron-accepting compound. Comparative Examples 3 to 9 are superior to Examples 1 to 10 in thermal response, but the storage stability of the image area is inferior to those in Examples 1 to 10.
[0090]
【The invention's effect】
A heat-sensitive recording material comprising a heat-sensitive recording layer comprising an electron-accepting usually colorless or light-colored dye precursor on a support and an electron-accepting compound that reacts upon heating to develop the dye precursor. By using a urea urethane compound represented by the general formula (1) as an electron-accepting compound in the recording layer and using the electron-accepting compound in combination with 4-hydroxy-4′-methyldiphenylsulfone, the electron-accepting compound is used. The thermal response and the color density are improved without impairing the storage stability of the image portion of the functional compound. The content mass ratio of the electron accepting compound and 4-hydroxy-4′-methyldiphenyl sulfone is preferably about 1 to 20 parts by mass, more preferably 5 to 5 parts by mass with respect to 1 part by mass of the electron accepting compound. About 10 parts by mass.
In the heat-sensitive recording material of the present invention, the color development sensitivity is remarkably improved by using the saturated fatty acid monoamide represented by the general formula (2) as an auxiliary sensitizer in the heat-sensitive recording layer.

Claims (2)

Thermosensitive recording comprising a thermosensitive recording layer comprising, as a main component, an electron-donating usually colorless or light-colored dye precursor on a support and an electron-accepting compound that reacts upon heating to develop the dye precursor. In the material, the thermosensitive recording layer contains a urea urethane compound represented by the general formula (1) as the electron-accepting compound, and further contains 4-hydroxy-4′-methyldiphenylsulfone. Thermal recording material.

2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer contains a saturated fatty acid monoamide represented by the general formula (2) as an auxiliary sensitizer.

(In the formula, R ₁ represents an alkyl group having 11 to 21 carbon atoms.)