JP4110732B2 - Photothermographic material and image recording method - Google Patents

Description

【００７８】
【化２】

【００７９】
現像後の銀色調を改良する目的で添加される色調剤としてはイミド類（例えば、フタルイミド）；環状イミド類、ピラゾリン−５−オン類、及びキナゾリノン（例えば、スクシンイミド、３−フェニル−２−ピラゾリン−５−オン、１−フェニルウラゾール、キナゾリン及び２，４−チアゾリジンジオン）；ナフタールイミド類（例えば、Ｎ−ヒドロキシ−１，８−ナフタールイミド）；コバルト錯体（例えば、コバルトのヘキサミントリフルオロアセテート）、メルカプタン類（例えば、３−メルカプト−１，２，４−トリアゾール）；Ｎ−（アミノメチル）アリールジカルボキシイミド類（例えば、Ｎ−（ジメチルアミノメチル）フタルイミド）；ブロックされたピラゾール類（例えば、Ｎ，Ｎ′−ヘキサメチレンビス（１−カルバモイル−３，５−ジメチルピラゾール））、イソチウロニウム（ｉｓｏｔｈｉｕｒｏｎｉｕｍ）誘導体及びある種の光漂白剤の組み合わせ（例えば１，８−（３，６−ジオキサオクタン）ビス（イソチウロニウムトリフルオロアセテート）及び２−（トリブロモメチルスルホニル）ベンゾチアゾールの組み合わせ）；メロシアニン染料（例えば、３−エチル−５−（（３−エチル−２−ベンゾチアゾリニリデン）−１−メチルエチリデン）−２−チオ−２，４−オキサゾリジンジオン）；フタラジノン、フタラジノン誘導体またはこれらの誘導体の金属塩（例えば、４−（１−ナフチル）フタラジノン、６−クロロフタラジノン、５，７−ジメチルオキシフタラジノン、及び２，３−ジヒドロ−１，４−フタラジンジオン）；フタラジノンとスルフィン酸誘導体の組み合わせ（例えば、６−クロロフタラジノンとベンゼンスルフィン酸ナトリウムまたは８−メチルフタラジノンとｐ−トリスルホン酸ナトリウム）；フタラジンとフタル酸の組み合わせ；フタラジン（フタラジンの付加物を含む）とマレイン酸無水物、及びフタル酸、２，３−ナフタレンジカルボン酸またはｏ−フェニレン酸誘導体及びその無水物（例えば、フタル酸、４−メチルフタル酸、４−ニトロフタル酸及びテトラクロロフタル酸無水物）から選択される少なくとも１つの化合物との組み合わせ；キナゾリンジオン類、ベンズオキサジン、ナルトキサジン誘導体；ベンズオキサジン−２，４−ジオン類（例えば、１，３−ベンズオキサジン−２，４−ジオン）；ピリミジン類及び不斉トリアジン類（例えば、２，４−ジヒドロキシピリミジン）、及びテトラアザペンタレン誘導体（例えば、３，６−ジメルカプト−１，４−ジフェニル−１Ｈ，４Ｈ−２，３ａ，５，６ａ−テトラアザペンタレン）。好ましい色調剤としては、フタラジノン、フタラジンが挙げられる。
【００８０】
なお、色調剤は本発明の目的を阻害しないのであれば後述する保護層に添加しても良い。
【００８１】
また、増感色素としては、例えばアルゴンイオンレーザー光源に対しは、特開昭６０−１６２２４７号、特開平２−４８６３５号、米国特許第２，１６１，３３１号、西独特許第９３６，０７１号、特願平３−１８９５３２号等に記載のシンプルメロシアニン類、ヘリウムネオンレーザー光源に対しては、特開昭５０−６２４２５号、同５４−１８７２６号、同５９−１０２２２９号に示された三核シアニン色素類、特願平６−１０３２７２号に記載されたメロシアニン類、ＬＥＤ光源及び赤外半導体レーザー光源に対しては特公昭４８−４２１７２号、同５１−９６０９号、同５５−３９８１８号、特開昭６２−２８４３４３号、特開平２−１０５１３５号に記載されたチアカルボシアニン類、赤外半導体レーザー光源に対しては特開昭５９−１９１０３２号、特開昭６０−８０８４１号に記載されたトリカルボシアニン類、特開昭５９−１９２２４２号、特開平３−６７２４２号の一般式（IIIａ）、（IIIｂ）に記載された４−キノリン核を含有するジカルボシアニン類等が有利に選択される。更に赤外レーザー光源の波長が７５０ｎｍ以上更に好ましくは８００ｎｍ以上である場合、このような波長域のレーザーに対応する為には、特開平４−１８２６３９号、同５−３４１４３２号、特公平６−５２３８７号、同３−１０９３１号、米国特許第５，４４１，８６６号、特開平７−１３２９５号等に記載されている増感色素が好ましく用いられる。
【００８２】
また、強色増感剤としてはＲＤ１７６４３、特公平９−２５５００号、同４３−４９３３号、特開昭５９−１９０３２号、同５９−１９２２４２号、特開平５−３４１４３２号等に記載されている化合物を適宜選択して用いることができ、本発明では、下記一般式（Ｍ）で表される複素芳香族メルカプト化合物、実質的に前記の複素芳香族メルカプト化合物を生成する一般式（Ｍａ）で表されるジスルフィド化合物を用いることができる。
【００８３】
一般式（Ｍ） Ａｒ−ＳＭ
一般式（Ｍａ） Ａｒ−Ｓ−Ｓ−Ａｒ
一般式（Ｍ）中、Ｍは水素原子又はアルカリ金属原子を表し、Ａｒは１個以上の窒素、硫黄、酸素、セレニウムもしくはテルリウム原子を有する複素芳香環又は縮合複素芳香環を表す。複素芳香環は、好ましくは、ベンズイミダゾール、ナフトイミダゾール、ベンゾチアゾール、ナフトチアゾール、ベンズオキサゾール、ナフトオキサゾール、ベンゾセレナゾール、ベンゾテルラゾール、イミダゾール、オキサゾール、ピラゾール、トリアゾール、トリアジン、ピリミジン、ピリダジン、ピラジン、ピリジン、プリン、キノリン又はキナゾリンである。また、一般式（Ｍａ）中のＡｒは上記一般式（Ｍ）の場合と同義である。
【００８４】
上記の複素芳香環は、例えば、ハロゲン原子（例えば、Ｃｌ、Ｂｒ、Ｉ）、ヒドロキシ基、アミノ基、カルボキシル基、アルキル基（例えば、１個以上の炭素原子、好ましくは、１〜４個の炭素原子を有するもの）及びアルコキシ基（例えば、１個以上の炭素原子、好ましくは、１〜４個の炭素原子を有するもの）からなる群から選ばれる置換基を有することができる。
【００８５】
さらに本発明において、高感度にするためには強色増感剤として下記に示すチウロニウム化合物を用いることがより好ましい。
【００８６】
【化３】

【００８７】
【化４】

【００８８】
強色増感剤は有機銀塩及びハロゲン化銀粒子を含む乳剤層中に銀１モル当たり０．００１〜１．０モルの範囲で用いるのが好ましく、特に銀１モル当たり０．０１〜０．５モルの範囲にするのが好ましい。
【００８９】
本発明の感光層にはヘテロ原子を含む大環状化合物を含有させることができる。ヘテロ原子として窒素原子、酸素原子、硫黄原子及びセレン原子の少なくとも１種を含む９員環以上の大環状化合物が好ましく、１２〜２４員環がより好ましく、更に好ましいのは１５〜２１員環である。
【００９０】
代表的な化合物としてはクラウンエーテルがあり、Ｃ．Ｊ．Ｐｅｄｅｒｓｏｎが１９６７年に合成し、その特異な報告以来、数多く合成されているものである。これらの化合物は、Ｃ．Ｊ．Ｐｅｄｅｒｓｏｎ，Ｊｏｕｒｎａｌ ｏｆ Ａｍｅｒｉｃａｎ ｃｈｅｍｉｃａｌ ｓｏｃｉｅｔｙ ｖｏｌ，８６（２４９５），７０１７〜７０３６（１９６７）、Ｇ．Ｗ．Ｇｏｋｅｌ，Ｓ．Ｈ，Ｋｏｒｚｅｎｉｏｗｓｋｉ，Ｍａｃｒｏｃｙｃｌｉｃ ｐｏｌｙｅｔｈｒ ｓｙｎｔｈｅｓｉｓ，Ｓｐｒｉｎｇｅｒ−Ｖｅｒｇａｌ，（１９８２）等に詳細に記載されている。
【００９１】
本発明の画像形成層には上述した添加剤以外に例えば、界面活性剤、酸化防止剤、安定化剤、可塑剤、紫外線吸収剤、被覆助剤等を用いても良い。これらの添加剤はＲｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ Ｉｔｅｍ１７０２９（１９７８年６月ｐ．９〜１５）に記載されている化合物を、本発明の目的を阻害しない範囲で適宜選択して用いることができる。
【００９２】
また、画像形成層のバインダー樹脂が活性水素を有する場合には、従来から公知の多官能イソシアネート化合物、アルコキシシラン化合物、アルコキシチタン化合物等の金属アルコキシド部分を複数個分子内に有する金属アルコキシドなどの架橋剤を添加して膜強度を向上させても良い。
【００９３】
本発明において、画像形成層は単層でも良く、組成が同一あるいは異なる複数の層で構成しても良い。なお、画像形成層の膜厚は通常１０〜３０μｍである。
【００９４】
好ましい態様の熱現像感光材料に用いられる保護層としては、上述のバッキング層および／または画像形成層で記載したバインダー樹脂と必要に応じて添加される添加剤により構成され、保護層のバインダー樹脂はバッキング層および／または画像形成層で記載したバインダー樹脂を適宜選択して用いることができる。
【００９５】
保護層に添加される添加剤としては、熱現像後の画像の傷つき防止や搬送性を確保する目的でフィラーを含有することが好ましく、フィラーを添加する場合の含有量は、層形成組成物中０．０５〜３０質量％含有することが好ましい。
【００９６】
本発明に用いられるフィラーとしては、バッキング層で用いられるフィラーを適時選択して用いることができる。
【００９７】
さらに、滑り性や帯電性を改良するために保護層には潤滑剤、帯電防止剤を含有しても良く、これらの化合物としては、バッキング層で用いられる潤滑剤と帯電防止剤を適時選択して用いることができる。
【００９８】
さらに、バッキング層、画像形成層と同様に、本発明の目的を阻害しない範囲で、保護層のバインダー樹脂が水酸基あるいは活性水素を有する場合には、従来から公知の多官能イソシアネート化合物、アルコキシシラン化合物、アルコキシチタン化合物等の金属アルコキシドの部分を複数個分子内に有する金属アルコキシドなどの架橋剤を添加して膜強度を向上させても良い。
【００９９】
これら添加剤の添加量は、保護層形成成分の０．０１〜２０質量％程度が好ましく、更に好ましくは、０．０５〜１０質量％である。
【０１００】
本発明において、保護層は単層でも良く、組成が同一あるいは異なるの複数層の層で構成しても良い。なお、保護層の膜厚は通常１．０〜５．０μｍである。
【０１０１】
本発明では、上述の画像形成層、支持体および保護層以外に、支持体と画像形成層との膜付を改良するために中間層を設置しても良く、設置する場合の中間層の厚みは通常０．０５〜２．０μｍである。
【０１０２】
ところで、後述する画像露光で用いられるイメージャで扱う画像信号はデジタル信号であるために、画像形成層側から見た場合に正像あるいは逆像として画像露光することも可能である。このことは、言い換えれば、シャーカステン上で熱現像後の熱現像感光材料を観察する際に、画像形成面側から観察することもできるし、バッキング層面から観察することもできるということになる。
【０１０３】
一方、好ましい態様では、支持体とバッキング層に含有される染料の各層の単位膜厚当りの濃度は、バッキング層の方が高濃度になる。そのため、シャーカステン面とバッキング層面とを対面させるか否かで、観察する人によっては若干の色味の違う場合が有り、この現象は特に、逆像露光しシャーカステン上の画像をバッキング層面から観察する場合に多く現れる。これは、単位膜厚当たりの染料濃度が高いバッキング層が、観察者に対して最も近い所に有るためと考えられるがはっきりした原因は判っていない。
【０１０４】
これらの課題点を解決するために、本発明の第１の態様として、熱現像感光材料を形成する支持体、バッキング層および画像形成層に同一の染料を含有させることを特徴としており、支持体、バッキング層および画像形成層は第一の態様で記載した組成物で構成することができる。また、バッキング層および画像形成層に必須成分として添加される染料は、第一の態様の支持体の記載で詳述した染料を指し、該染料は支持体で添加される染料と同一であれば特に制限はなく用いることができる。
【０１０５】
なお、支持体に用いる染料を複数種用いる場合には、バッキング層、画像形成層に添加する染料も支持体に用いたものと同種の染料を用い、且つ染料の質量比率も同じに設定される。
【０１０６】
さらに第１の態様においては、染料を含有した支持体の透過濃度をＴｓ２、染料を含有した画像形成層の透過濃度をＴｉ２、染料を含有したバッキング層の透過濃度をＴｂ２としたとき、Ｔｓ２、Ｔｉ２およびＴｂ２の関係が０．１０≦Ｔｓ２／（Ｔｉ２＋Ｔｂ２）≦４．００である。Ｔｉ２およびＴｂ２はそれぞれ０．００よりは大きい数値となるが、実技的には０．１２０を越えない値である。
【０１０７】
Ｔｓ２、Ｔｉ２およびＴｂ２の関係が０．１０≦Ｔｓ２／（Ｔｉ２＋Ｔｂ２）≦４．００にあることにより、好ましい態様で記載したように、支持体製膜時の染料劣化を低減させることができる。
【０１０８】
第１の態様では、Ｔｉ２およびＴｂ２が０．００ではないことが必須であり、通常、Ｔｉ２の値としては０．０２０以上にすることが好ましい。またＴｉ２は０．２００以下が好ましく、実技的には０．１２０以内である。また、Ｔｉ２とＴｂ２の比率としては０．０７≦Ｔｂ２／Ｔｉ２≦７．１８、さらには０．１０≦Ｔｂ２／Ｔｉ２≦５．００の範囲にするのが好ましい。
【０１０９】
本発明の第２の態様として、熱現像感光材料を形成する支持体、画像形成層、保護層およびバッキング層に同一の染料を含有させることを特徴としており、支持体、画像形成層、保護層およびバッキング層は好ましい態様で記載した組成物で構成することができる。また、画像形成層、保護層およびバッキング層に必須成分として添加される染料は、好ましい態様の支持体の記載で詳述した染料を指し、該染料は支持体で添加される染料と同一であれば特に制限はなく用いることができる。
【０１１０】
なお、支持体に用いる染料を複数種用いる場合には、画像形成層、保護層およびバッキング層に添加する染料も支持体に用いたものと同種の染料を用い、且つ染料の質量比率も同じに設定される。
【０１１１】
さらに第２の態様は、染料を含有した支持体の透過濃度をＴｓ３、染料を含有した画像形成層の透過濃度をＴｉ３、染料を含有した画像形成層の透過濃度をＴｐ３、染料を含有したバッキング層の透過濃度をＴｂ３としたとき、Ｔｓ３、Ｔｉ３、Ｔｐ３およびＴｂ３の関係が０．１０≦Ｔｓ３／（Ｔｉ３＋Ｔｐ３＋Ｔｂ３）≦４．００であることが好ましい。
【０１１２】
本発明の第２の態様においても、前述の第１の態様同様に０．１０≦Ｔｓ３／（Ｔｉ３＋Ｔｐ３＋Ｔｂ３）≦４．００の関係にあることにより、支持体製膜時の染料劣化を低減させることができる。
【０１１３】
第２の態様では、Ｔｉ３、Ｔｐ３およびＴｂ３が０．００ではないことが必須であり、通常、Ｔｉ３＋Ｔｐ３の値としては０．０２０以上にすることが好ましく、また０．２００以下が好ましく、実技的には０．１２０以内である。また、Ｔｉ３＋Ｔｐ３とＴｂ３の比率としては０．０７≦Ｔｂ３／（Ｔｉ３＋Ｔｐ３）≦７．１８、さらには０．１０≦Ｔｂ３／（Ｔｉ３＋Ｔｐ３）≦５．００の範囲にするのが好ましい。
【０１１４】
一方、後述する熱現像時に加熱ドラムと保護層とを接触させる場合には、保護層形成組成物中の染料比率が多い場合には、加温時の層自体の染料保持力が不足し、染料の種類によっては保護層表面にブリードあるいはドラム表面に転写してしまう場合がある。そのため、染料、バインダー樹脂および添加される各種添加剤の種類により一概に規定することはできないが、保護層に含有する染料は通常層形成組成物中０．０１〜２．０質量％、さらには０．０５〜１．０質量％の範囲にするのが好ましい。
【０１１５】
前述したように、本発明の第１の態様あるいは第２の態様で示した関係にすることで、シャーカステン上の画像をバッキング層面から目視観察する場合に、未露光部の色調の変化の少ない画像を得ることができる。
【０１１６】
好ましい態様、本発明の第１の態様および第２の態様で用いられる支持体は、公知の方法を用いて製造することができる。本発明において好ましい支持体であるポリエステルフィルムについて具体的に説明すると、まず十分乾燥されたポリエステルペレットを公知の溶融押出機に供給し、さらに本発明で必須である染料および必要応じて添加される各種添加剤を添加して十分混錬し、必要に応じて選ばれたフィルターを通過させた後、Ｔ型口金により、回転する金属製キャスティングドラム上にシート状に押し出し、冷却固化せしめて無配向状態のフィルムを得る。もしくは未乾燥ペレットをベント式押出機に供給し同様にして無配向状態のフィルムを得る。また、この無配向状態のフィルムのエッジ部の最大厚み（Ａ）と幅方向中央部の厚み（Ｂ）との比（Ａ／Ｂ）は、２．０〜６．０の範囲に制御することが好ましい。この場合、長手方向延伸工程での、蛇行、幅変動、延伸むら、破断頻度を効果的に抑えることが出来る。
【０１１７】
なお、支持体を成形する際に用いる十分乾燥されたポリエステルペレットは、リサイクルされた染料の入っていないポリエステルペレット、感光材料あるいは熱現像感光材料に用いられていた青色に着色されたポリエステルペレットを含んでいる。
【０１１８】
上述のようにして得られた無配向状態のポリエステルフィルムを縦横二軸に延伸する。ここで言う縦とはフィルム長手方向を意味し、横とは幅方向を意味する。この縦横二軸延伸は逐次二軸方式、もしくは同時二軸方式により行われる。逐次二軸方式ではロールの周速差を利用して縦方向に延伸し、特に限定されるものではないがステンターを用いて横方向に延伸する。縦方向と横方向の延伸の順序は特に限定されるものではない。また、同時二軸方式では同時二軸テンターを用いて延伸する。この縦横二軸延伸における延伸温度は、ポリエステルのガラス転移温度（Ｔｇ）〜（Ｔｇ）＋６０℃の範囲であり、より好ましい延伸温度は（Ｔｇ）＋１５℃〜（Ｔｇ）＋４５℃の範囲である。延伸倍率は逐次二軸方式、同時二軸方式ともにフィルム長手方向と幅方向の合計延伸倍率が１．５倍〜８倍の範囲、より好ましくは２．５倍〜６倍の範囲である。尚、ここで言う合計延伸倍率とは長手方向倍率×幅方向倍率である。
【０１１９】
また、好ましい態様、本発明の第１の態様および第２の態様で設置されるバッキング層、画像形成層、保護層およびおよび必要に応じて設置される中間層等は、上述で述べた成分を、それぞれ溶媒に溶解若しくは分散して塗工液を調製する。
【０１２０】
溶媒としては、有機合成化学協会編の“溶剤ポケットブック”等に示されている溶解度パラメーターの値が６．０〜１５．０の範囲のものであればよく、本発明において用いられる各層を形成する塗工液に用いる溶媒としては、例えば、ケトン類としてアセトン、イソフォロン、エチルアミルケトン、メチルエチルケトン、メチルイソブチルケトン等が挙げられる。アルコール類としてメチルアルコール、エチルアルコール、ｎ−プロピルアルコール、イソプロピルアルコール、ｎ−ブチルアルコール、イソブチルアルコール、ジアセトンアルコール、シクロヘキサノール、ベンジルアルコール等が挙げられる。グリコール類としてエチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、ヘキシレングリコール等が挙げられる。エーテルアルコール類としてエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル等が挙げられる。エーテル類としてエチルエーテル、ジオキサン、イソプロピルエーテル等が挙げられる。
【０１２１】
エステル類としては、酢酸エチル、酢酸ブチル、酢酸アミル、酢酸イソプロピル等が挙げられる。炭化水素類としてｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、シクロヘキサン、ベンゼン、トルエン、キシレン等が挙げられる。塩化物類として塩化メチル、塩化メチレン、クロロホルム、ジクロロベンゼン等が挙げられるが、但し、本発明の効果を阻害しない範囲であればこれらに限定されない。
【０１２２】
また、これらの溶媒は、単独、または、数種類組合わせて使用できる。尚、画像形成材料中の上記溶媒の含有量は塗布工程後の乾燥工程等における温度条件等の条件変化によって調整できるが、熱現像感光材料中に含有される残存溶媒の量は合計量で５〜１０００ｍｇ／ｍ²が好ましく、更に好ましくは、１０〜３００ｍｇ／ｍ²である。
【０１２３】
塗工液を形成する際に分散が必要な場合には、二本ロールミル、三本ロールミル、ボールミル、ペブルミル、コボルミル、トロンミル、サンドミル、サンドグラインダー、Ｓｑｅｇｖａｒｉアトライター、高速インペラー分散機、高速ストーンミル、高速度衝撃ミル、ディスパー、高速ミキサー、ホモジナイザ、超音波分散機、オープンニーダー、連続ニーダー等、従来から公知の分散機を適宜選択してを用いることができる。
【０１２４】
上述のようにして調製した、塗工液を塗工するには、エクストルージョン方式の押し出しコータ、リバースロールコータ、グラビアロールコータ、エアドクターコータ、ブレードコータ、エアナイフコータ、スクイズコータ、含浸コータ、バーコータ、トランスファロールコータ、キスコータ、キャストコータ、スプレーコータ等の、公知の各種コータステーションを適時選択して用いることができる。これらのコータの中で、該層の厚みムラを無くすために、エクストルージョン方式の押し出しコータやリバースロールコータ等のロールコータを用いることが好ましい。
【０１２５】
又、保護層を塗工するには場合には、画像形成層がダメージを受けないものであれば特に制限はないが、保護層形成塗工液に用いられる溶媒が、画像形成層を溶解する可能性がある場合には、上述したコータステーションの中で、エクストルージョン方式の押し出しコータ、グラビアロールコータ、バーコータ等を使用することができる。尚、これらの中でグラビアロールコータ、バーコータ等接触する塗工方法を用いる場合には、搬送方向に対して、グラビアロールやバーの回転方向は順転でもリバースでも良く、また順転の場合には等速でも、周速差を設けても良い。
【０１２６】
更に、上述のように各層毎に塗布乾燥を繰り返してもよいが、ウェット−オン−ウェット方式で重層塗布して乾燥させても良い。その場合、リバースロールコータ、グラビアロールコータ、エアドクターコータ、ブレードコータ、エアナイフコータ、スクイズコータ、含浸コータ、バーコータ、トランスファロールコータ、キスコータ、キャストコータ、スプレーコータ等とエクストルージョン方式の押し出しコータとの組み合わせにより塗布することができ、この様なウェット−オン−ウェット方式における重層塗布においては、下側の層が湿潤状態になったままで上側の層を塗布するので、上下層間の接着性が向上する。
【０１２７】
次に、上述の熱現像感光材料の好適な画像記録方法について詳述する。
本発明の画像記録方法としては、露光面とレーザ光のなす角度、レーザの波長、使用するレーザの数により三つの態様に大別され、それらを単独で行っても良いし、二種以上の態様を組み合わせても良く、このような画像形成方法にすることで干渉縞のない鮮明な画像を得ることができる。
【０１２８】
本発明の画像記録方法における第１の態様としては、熱現像感光材料の露光面とレーザ光のなす角が実質的に垂直になることがないレーザ光を用いて、走査露光により画像を形成することを特徴としている。このように、入射角を垂直からずらすことにより、仮に層間界面での反射光が発生した場合においても、画像形成層に達する光路差が大きくなることから、レーザ光の光路での散乱や減衰が生じて干渉縞が発生しにくくなる。なお、ここで、「実質的に垂直になることがない」とはレーザ走査中に最も垂直に近い角度として好ましくは５５度以上８８度以下、より好ましくは６０度以上８６度以下、更に好ましくは６５度以上８４度以下であることをいう。
【０１２９】
また、本発明の画像記録方法における第２の態様としては、露光波長が単一でない縦マルチレーザを用いて、走査露光により画像を形成することを特徴としている。このような、波長に幅を有する縦マルチレーザ光で走査すると縦単一モードの走査レーザ光に比べ、干渉縞の発生が低減される。なお、ここで言う縦マルチとは、露光波長が単一でないことを意味し、通常露光波長の分布が５ｎｍ以上、好ましくは１０ｎｍ以上になるとよい。露光波長の分布の上限には特に制限はないが、通常６０ｎｍ程度である。
【０１３０】
さらに、本発明の画像記録方法における第３の態様としては、２本以上のレーザを用いて、走査露光により画像を形成することを特徴としている。
【０１３１】
このような複数本のレーザを利用した画像記録方法としては、高解像度化、高速化の要求から１回の走査で複数ラインずつ画像を書き込むレーザプリンタやデジタル複写機の画像書込み手段で使用されている技術であり、例えば特開昭６０−１６６９１６号公報等により知られている。これは、光源ユニットから放射されたレーザ光をポリゴンミラーで偏向走査し、ｆθレンズ等を介して感光体上に結像する方法であり、これはレーザイメ−ジャなどと原理的に同じレーザ走査光学装置である。
【０１３２】
レーザプリンタやデジタル複写機の画像書込み手段における感光体上へのレーザ光の結像は、１回の走査で複数ラインずつ画像を書き込むという用途から、一つのレーザ光の結像位置から１ライン分ずらした位置に次のレーザ光の結像位置がある。具体的には、二つの光ビームは互いに副走査方向に像面上で数１０μｍオーダーの間隔で近接しており、印字密度が４００ｄｐｉ（本発明においては、１インチ即ち、２．５４ｃｍ当たりに１ドットの印字密度のことをｄｐｉ（ドットパーインチ）と定義する）で２ビームの副走査方向ピッチは６３．５μｍ、６００ｄｐｉで４２．３μｍである。このような、副走査方向に解像度分ずらした方法とは異なり、本発明では同一の場所に２本以上のレーザを入射角を変え露光面に集光させ画像形成することを特徴としている。この際の、通常の１本のレーザ（波長λ〔ｎｍ〕）で書き込む場合の露光面での露光エネルギーがＥである場合に、露光に使用するＮ本のレーザが同一波長（波長λ〔ｎｍ〕）、同一露光エネルギー（Ｅｎ）とした場合、０．９×Ｅ≦Ｅｎ×Ｎ≦１．１×Ｅの範囲にするのが好ましい。このようにすることにより、露光面ではエネルギーは確保されるが、それぞれのレーザ光の画像形成層への反射は、レーザの露光エネルギーが低いため低減され、ひいては干渉縞の発生が押えられる。
【０１３３】
なお、上述では複数本のレーザの波長をλと同一のものを使用したが、波長の異なるものを用いても良い。この場合、λ〔ｎｍ〕に対して（λ−３０）＜λ１、λ２、・・・・・λｎ≦（λ＋３０）の範囲にするのが好ましい。
【０１３４】
さらに、上述した第１、第２および第３の態様の画像記録方法において、走査露光に用いるレーザとしては、一般によく知られている、ルビーレーザ、ＹＡＧレーザ、ガラスレーザ等の固体レーザ；Ｈｅ−Ｎｅレーザ、Ａｒイオンレーザ、Ｋｒイオンレーザ、ＣＯ₂レーザ、ＣＯレーザ、Ｈｅ−Ｃｄレーザ、Ｎ₂レーザ、エキシマーレーザ等の気体レーザ；ＩｎＧａＰレーザ、ＡｌＧａＡｓレーザ、ＧａＡｓＰレーザ、ＩｎＧａＡｓレーザ、ＩｎＡｓＰレーザ、ＣｄＳｎＰ₂レーザ、ＧａＳｂレーザ等の半導体レーザ；化学レーザ、色素レーザ等を用途に併せて適宜選択して使用できるが、これらの中でもメンテナンスや光源の大きさの問題から、波長が７００〜１２００ｎｍの半導体レーザを用いるのが好ましい。
【０１３５】
なお、レーザ・イメージャやレーザ・イメージセッタで使用されるレーザにおいて、熱現像感光材料を走査するときの該材料露光面でのビームスポット径は、一般に短軸径として５〜７５μｍ、長軸径として５〜１００μｍの範囲であり、レーザ光走査速度は熱現像感光材料固有のレーザ発振波長における感度とレーザパワーによって、熱現像感光材料毎に最適な値に設定することができる。
【０１３６】
【実施例】
以下、本発明を実施例によって詳細に説明するが、本発明はこれらにより限定されない。尚、文中の％は特に断りのない限り質量％を表す。
【０１３７】
参考例
〈熱現像感光材料の作製〉
下記に示す方法で、バッキング層形成塗工液を調製した。
【０１３８】
（バッキング層形成塗工液の調製）
メチルエチルケトン８３ｇに攪拌しながら、酢酸酪酸セルロース（イーストマンケミカル社製、ＣＡＢ３８１−２０）８．４２ｇ、ポリエステル樹脂（東洋紡績（株）製、バイロン２８０）０．４５ｇを添加し溶解した。この溶解した液に１．０３ｇの赤外染料１を添加した。
【０１３９】
別途、メタノール４．３２ｇにＦ系界面活性剤（旭硝子（株）製、サーフロンＳ−３８１（有効成分７０％））０．６４ｇとＦ系界面活性剤（大日本インキ工業（株）製、メガファッグＦ１２０Ｋ）０．２３ｇを溶解させ、赤外染料１の入った溶液に、Ｆ系界面活性剤溶液を添加して、前記赤外染料１が完全に溶解するまで充分に攪拌を行った。最後にメチルエチルケトンに１％の濃度でディゾルバ型ホモジナイザにて分散したシリカ（Ｗ．Ｒ．グレース社製、サイロイド６４Ｘ６０００）を７．５ｇ、およびメチルエチルケトンに０．７０％の濃度で溶解した青色着色染料（Ｃ．Ｉ．Ｓｏｌｖｅｎｔ Ｂｌｕｅ ９７、λｍａｘ＝６３０ｎｍ：キシレン）を順次添加、攪拌しバッキング層形成塗工液を調製した。
【０１４０】
別途、新規なポリエチレンテレフタレートペレットを溶融させ、この中に青色着色染料としてＣ．Ｉ．Ｓｏｌｖｅｎｔ Ｂｌｕｅ ９７を添加して、２０分間充分に溶融混錬した後、公知の製膜方法で表１の様な透過濃度Ｔｓ１［コニカ（株）製、ＰＤＡ−６５：小数点以下３桁、ビジュアル濃度を測定］となるように、厚さ１７５μｍの２軸延伸ポリエチレンテレフタレートフィルムを製膜し１０種のポリエチレンテレフタレートフィルム支持体を作製した。
【０１４１】
これらの支持体の片面をコロナ放電処理（８Ｗ／ｍ²・分）を施した後、上述のバッキング層形成塗工液を、コロナ放電処理面に乾燥膜厚が３．５ｇ／ｍ²になるように押し出しコータにて塗工した後、乾燥させ表１の透過濃度の青色着色染料を含有するバッキング層をそれぞれ形成し１０種の、バッキング層を形成したポリエチレンテレフタレートフィルム支持体を得た。尚、染料の量は仕上がりの熱現像感光材料の透過濃度が０．１９９±０．０２の範囲内にはいるように調整し、青色着色染料を含有したバッキング層の透過濃度Ｔｂ１は、支持体とバッキング層を合わせた透過濃度から支持体の透過濃度を差し引いた値とした。
【０１４２】
また、下記に示す方法で、画像形成層形成塗工液および保護層形成塗工液を別々に調製した。
【０１４３】
（画像形成層形成塗工液の調製）
水９００ｍｌ中に平均分子量１０万のオセインゼラチン７．５ｇ及び臭化カリウム１０ｍｇを溶解して温度３５℃、ｐＨを３．０に合わせた後、硝酸銀７４ｇを含む水溶液３７０ｍｌと（９８／２）のモル比の臭化カリウムと沃化カリウムを硝酸銀と等モル及び塩化イリジウムを銀１モル当たり１×１０^-4モル含む水溶液３７０ｍｌを、ｐＡｇ７．７に保ちながらコントロールドダブルジェット法で１０分間かけて添加した。その後４−ヒドロキシ−６−メチル−１，３，３ａ，７−テトラザインデン０．３ｇを添加しＮａＯＨでｐＨを５に調整して平均粒子サイズ０．０６μｍ、粒子サイズの変動係数１２％、（１００）面比率８７％の立方体沃臭化銀粒子を得た。この乳剤をゼラチン凝集剤を用いて凝集沈降させ脱塩処理した後、フェノキシエタノール０．１ｇを加え、ｐＨ５．９、ｐＡｇ７．５に調整して、感光性ハロゲン化銀乳剤１を得た。
【０１４４】
別途、４７２０ｍｌの純水にベヘン酸１１１．４ｇ、アラキジン酸８３．８ｇ、ステアリン酸５４．９ｇを８０℃で溶解した。次に高速で攪拌しながら１．５Ｍの水酸化ナトリウム水溶液５４０．２ｍｌを添加し濃硝酸６．９ｍｌを加えた後、５５℃に冷却して脂肪酸ナトリウム溶液を得た。
【０１４５】
調製した脂肪酸ナトリウム溶液の温度を５５℃に保ったまま、感光性ハロゲン化銀乳剤１（銀０．０３８モルを含む）と純水４５０ｍｌを添加し５分間攪拌した。次に１Ｍの硝酸銀溶液７６０．６ｍｌを２分間かけて添加し、さらに２０分攪拌し、濾過により水溶性塩類を除去した。その後、濾液の電導度が２μＳ／ｃｍになるまで脱イオン水による水洗、濾過を繰り返し、遠心脱水を実施した後、３７℃にて質量減がなくなるまで温風乾燥を行い、粉末有機銀塩Ａを得た。
【０１４６】
次いで、ポリビニルブチラール樹脂（積水化学工業（株）製、エスレックＢＬ−５Ｚ）１４．５７ｇをメチルエチルケトン１４５７ｇに溶解し、ディゾルバ型ホモジナイザにて攪拌しながら、調製した５００ｇの粉末有機銀塩Ａを徐々に添加して十分に混合した。その後粒子径１ｍｍ径のジルコニアビーズ（東レ（株）製）を８０％充填したメディア分散機（Ｇｅｔｔｚｍａｎｎ社製）にて周速１３ｍ、ミル内滞留時間０．５分間にて分散を行ない感光性乳剤分散液を調製した。
【０１４７】
さらに、感光性乳剤分散液５０ｇ及びメチルエチルケトン１０．０ｇを混合し攪拌しながら１８℃に保温し、かぶり防止剤１のメタノール溶液（１１．２％）を０．３２０ｇを加え１時間攪拌した。更に臭化カルシウムのメタノール溶液（１１．２％）０．２１２ｇを添加して２０分攪拌し、次いで、別途メタノール１０．０ｇに、１．００ｇのジベンゾ−１８−クラウン−６と０．３１ｇの酢酸カリウムを溶解させた溶液を０．３４３ｇ添加して１０分間撹拌した。次に、下記の色素溶液１を４．３９５ｇ添加して５０分間攪拌した後、０．０３８０ｇのチウロニウム化合物（例示化合物２−７）を添加し１０分間撹拌させた後に、温度を１３℃まで低下させ更に６０分攪拌した。
【０１４８】
（色素溶液１）
赤外増感色素１ ０．００８６ｇ
安息香酸誘導体１ ２．４７６ｇ
メチルエチルケトン ２５．００ｇ
この、色素溶液を添加した溶液を１３℃に保温したまま、ポリビニルブチラール樹脂（積水化学工業（株）製、エスレックＢＬ−５Ｚ）１３．２９ｇとテトラクロロフタル酸０．３０４ｇを順次添加し、充分撹拌溶解させた。
【０１４９】
この溶液に、別途メチルエチルケトンにそれぞれ溶解させた以下の添加物溶液１、２、３、４をそれぞれ２．２６１ｇ、１３．５４３ｇ、３．４９１ｇ、４．５９７ｇを順次撹拌しながら撹拌し画像形成層形成塗工液を調製した。
【０１５０】

【０１５１】
【化５】

【０１５２】
（保護層形成塗工液の調製）
メチルエチルケトン８６．５ｇに攪拌しながら、１０．０５ｇの酢酸酪酸セルロース（イーストマンケミカル社製、ＣＡＢ１７１−１５）、ベンゾトリアゾール０．０２５ｇ、フッ素系活性剤（旭硝子（株）製、サーフロンＫＨ４０）０．１０ｇを添加し溶解した。
【０１５３】
別途、固形分１５％で酢酸酪酸セルロース（イーストマンケミカル社製、ＣＡＢ１７１−１５）をメチルエチルケトンに溶解させた５５．０ｇの溶液に、シリカ（富士シリシア化学（株）製、サイリシア３２０）を５．０ｇ添加して、ジルコニアビーズを充填したメディア分散機で分散し、シリカ分散液を調製した。次いで、上述のベンゾトリアゾールを溶解した樹脂溶液を撹拌しながら、シリカ分散液３．０ｇを添加した後、超音波分散し保護層形成塗工液を調製した。
【０１５４】
次いで、前記バッキング層を形成した厚さ１７５μｍの２軸延伸ポリエチレンテレフタレートフィルムのバッキング層とは反対面にそれぞれコロナ放電処理（８Ｗ／ｍ²・分）を施し、このコロナ放電処理面上に、上述の方法で調製した画像形成層形成塗工液と保護層形成塗工液を押し出しコータを用いて重層塗工後、７０℃の温風で乾燥させ熱現像感光材料１〜１０を作製した。なお、乾燥後の膜厚は画像形成層が２１．０±１．５ｇ／ｍ²、保護層が２．３５±０．１５ｇ／ｍ²となるように調整した。
【０１５５】
〈画像記録方法および画像の評価〉
上述の熱現像感光材料１〜１０を遮光下、室温１２０時間保存したものを用いて、それぞれの材料の保護層面側から、高周波重畳にて波長８００ｎｍ〜８２０ｎｍの縦マルチモード化された半導体レーザを露光源とした露光機により、露光量を変化させレーザ走査による露光を行い、続けてヒートドラムを有する自動現像機を用いて、熱現像感光材料の保護層とドラム表面が接触するようにして、１２６℃で１３秒熱現像処理し画像形成を行った。
【０１５６】
得られた露光・熱現像処理された熱現像感光材料各試料を画像色調、未露光部の色調と画像部の色調を画像目視での官能評価によりそれぞれ下記の基準で評価した。得られた結果を表１に示す。
【０１５７】
（画像色調）
透過濃度を濃度計（Ｘ−Ｒｉｔｅ社製、カラー透過濃度計３１０Ｔ）で測定し、Ｖｉｓｕａｌ濃度で未露光部分よりも＋１．０高い濃度を与える濃度［Ｖ１］とその際のＢｌｕｅ濃度［Ｂ１］の比Ｂ１／Ｖ１で評価した。なお、未露光部＋１．０となるＶｉｓｕａｌ濃度は、濃度が未露光部＋０．７〜＋１．２となる濃度の間を少なくとも３点以上測定し回帰直線により求め、対応するＢｌｕｅ濃度は、Ｖｉｓｕａｌ濃度に対応するＢｌｕｅ濃度の回帰直線とＶｉｓｕａｌ濃度が未露光部＋１．０となる点から算出した。
【０１５８】
（官能評価）
輝度１００００カンデラ／ｍ²のシャーカステン上で画像を保護層面から目視観察し、未露光部の色調と画像部の色調を下記の基準で評価した。なお、十分では無かった場合は「赤みがある」、若しくは「黄色みがある」という回答であった。
【０１５９】
未露光部色調：医療の画像形成材料あるいはシステムを開発している１００人に目視観察してもらい色調として十分か否かを判断してもらった。
【０１６０】
４‥‥‥９５％以上のひとが十分と回答
３‥‥‥９０％以上、９５％未満のひとが十分と回答
２‥‥‥８０％以上、９０％未満のひとが十分と回答
１‥‥‥十分と答えたひとが８０％未満
画像部色調：透過濃度０．３〜３．０のウェッジパターンを医療の画像形成材料あるいはシステムを開発している１００人に目視観察してもらい黒色画像の色調として十分か否かを判断してもらった。
【０１６１】
４‥‥‥９５％以上のひとが十分と回答
３‥‥‥９０％以上、９５％未満のひとが十分と回答
２‥‥‥８０％以上、９０％未満のひとが十分と回答
１‥‥‥十分と答えたひとが８０％未満
【０１６２】
【表１】

【０１６３】
実施例１
〈熱現像感光材料の作製〉
バッキング層付きの厚さ１７５μｍのポリエチレンテレフタレートフィルム支持体を実施例１と同様の方法で作製した。なお、作製した支持体およびバッキング層の透過濃度を表２に示す。バッキング層の透過濃度は参考例と同様に青色着色染料の添加量を調整した。支持体および作製したバッキング層の透過濃度を表２に示す。
【０１６４】
また、参考例と同様な方法で、色素溶液１まで添加した画像形成層形成塗工液を調製し、この溶液を１３℃に保温したまま、ポリビニルブチラール樹脂（積水化学工業（株）製、エスレックＢＬ−５Ｚ）１３．２９ｇとテトラクロロフタル酸０．３０４ｇを順次添加し充分撹拌溶解させた。
【０１６５】
この溶液に、別途メチルエチルケトンに０．７０％の濃度で溶解した青色着色染料（Ｃ．Ｉ．Ｓｏｌｖｅｎｔ Ｂｌｕｅ ９７）を添加した後、メチルエチルケトンにそれぞれ溶解させた参考例の添加物溶液１、２、３、４をそれぞれ２．２６１ｇ、１３．５４３ｇ、３．４９１ｇ、４．５９７ｇを順次撹拌しながら撹拌し画像形成層形成塗工液を調製した。
【０１６６】
次いで、前記バッキング層付きポリエチレンテレフタレートフィルム支持体のバッキング層とは反対面をコロナ放電処理（８Ｗ／ｍ²・分）を施し、このコロナ放電処理面上に、上述の方法で調製した画像形成層形成塗工液と参考例の保護層形成塗工液を押し出しコータを用いて重層塗工後、７０℃の温風で乾燥させ熱現像感光材料１１〜２２を作製した（画像形成層形成塗工液の青色着色染料の量を調整し画像形成層の透過濃度を調整した）。なお、乾燥後の膜厚は画像形成層が２１．０±１．５ｇ／ｍ²、保護層が２．３５±０．１５ｇ／ｍ²となるように調製した。熱現像感光材料各試料の画像形成層の透過濃度Ｔｉ２を支持体およびバッキング層の透過濃度とともに表２に示した。
【０１６７】
なお、青色着色染料を含有した画像形成層の透過濃度Ｔｉ２は、未処理のポリエチレンテレフタレートフィルム上に保護層のみを塗布・乾燥した際の透過濃度、上述の画像形成層形成塗工液と参考例の保護層形成塗工液を押し出しコータを用いて、前述の保護層のみを塗布したポリエチレンテレフタレートフィルム上重層塗布・乾燥させた際の透過濃度との差し引きから求めた。
【０１６８】
次いで、上述の熱現像感光材料各試料を参考例と同様の方法で画像形成し、得られた露光・熱現像処理された試料の画像色調について参考例と同じ基準で、又未露光部色調と画像部色調について画像目視での官能評価をそれぞれ下記の基準で評価した。得られた結果を表２に示す。
【０１６９】
（官能評価）
輝度１００００カンデラ／ｍ²のシャーカステン上で画像を保護層面とバッキング層面から目視観察し、未露光部の色調と画像部の色調を下記の基準で評価した。なお、十分では無かった場合は「赤みがある」、若しくは「黄色みがある」という回答であった。
【０１７０】
未露光部色調：医療の画像形成材料あるいはシステムを開発している１００人に目視観察してもらい色調として十分か否かを判断してもらった。
【０１７１】
４‥‥‥９５％以上のひとが十分と回答
３‥‥‥９０％以上、９５％未満のひとが十分と回答
２‥‥‥８０％以上、９０％未満のひとが十分と回答
１‥‥‥十分と答えたひとが８０％未満
画像部色調：透過濃度０．３〜３．０のウェッジパターンを医療の画像形成材料あるいはシステムを開発している１００人に目視観察してもらい黒色画像の色調として十分か否かを判断してもらった。
【０１７２】
４‥‥‥９５％以上のひとが十分と回答
３‥‥‥９０％以上、９５％未満のひとが十分と回答
２‥‥‥８０％以上、９０％未満のひとが十分と回答
１‥‥‥十分と答えたひとが８０％未満
【０１７３】
【表２】

【０１７４】
実施例２
〈熱現像感光材料の作製〉
バッキング層付きの厚さ１７５μｍのポリエチレンテレフタレートフィルム支持体を参考例と同様の方法で作製した。なお、作製した支持体およびバッキング層の透過濃度を表３に示す。
【０１７５】
また、実施例１と同様な方法で、青色着色染料を含有する画像形成層形成塗工液を調製し、別途、参考例の超音波分散して調製した保護層形成塗工液に、別途メチルエチルケトンに０．７０％の濃度で溶解した青色着色染料（Ｃ．Ｉ．Ｓｏｌｖｅｎｔ Ｂｌｕｅ ９７）を添加し、十分に撹拌した後、再度超音波分散して保護層形成塗工液を調製した。
【０１７６】
次いで、作製したバッキング層付きの厚さ１７５μｍの２軸延伸ポリエチレンテレフタレートフィルムのバッキング層とは反対面にコロナ放電処理（８Ｗ／ｍ²・分）を施し、このコロナ放電処理面上に、実施例１と同様の方法で調製した画像形成層形成塗工液と上述の方法で青色着色染料を添加し調製した保護層形成塗工液を押し出しコータを用いて重層塗工後、７０℃の温風で乾燥させ熱現像感光材料を作製した。なお、乾燥後の膜厚は画像形成層が２１．０±１．５ｇ／ｍ²、保護層が２．３５±０．１５ｇ／ｍ²となるように調整した。また画像形成層および保護層の透過濃度はそれぞれの塗工液の青色着色染料の添加量を変えることで調整した。この様にして作製した熱現像感光材料２３〜３４について保護層、画像形成層の透過濃度を前記の支持体およびバッキング層の透過濃度とともに表３に示した。
【０１７７】
なお、青色着色染料を含有した保護層の透過濃度Ｔｐ３は、未処理ポリエチレンテレフタレートフィルム上に保護層のみを塗布・乾燥した際の透過濃度を測定し、また、画像形成層の透過濃度Ｔｉ３は、本実施例で作製した熱現像感光材料の透過濃度から、前述の保護層のみの透過濃度と２軸延伸ポリエチレンテレフタレートフィルム上にバッキング層を積層したものの透過濃度の差し引きから求めた。
【０１７８】
次いで、上述の熱現像感光材料各試料を参考例と同様の方法で画像形成し、得られた露光・熱現像処理された画像の色調を参考例と同じ基準で、目視での未露光部色調、画像部色調についての官能評価を実施例１と同じ基準で評価した。得られた結果を表３に示す。
【０１７９】
【表３】

【０１８０】
実施例３
参考例の熱現像感光材料１、３〜８および１０で用いた支持体を製膜する際に、青色着色染料と新規なポリエチレンテレフタレートペレットの溶融混錬時間を３倍にした以外は、参考例と同様に熱現像感光材料を作製し熱現像感光材料３５〜４２を得た。
【０１８１】
この熱現像感光材料各試料を参考例と同様の方法で画像形成し、得られた露光・熱現像処理された画像の色調、未露光部色調および画像部色調を目視での官能評価により参考例と同じ基準で評価した。得られた結果を表４に示す。
【０１８２】
【表４】

【０１８３】
実施例４
支持体を製膜する際に使用するポリエチレンテレフタレートペレットを、表５に示す割合で新規なポリエチレンテレフタレートペレットに混合して一度フィルムにした透過濃度で０．１６０のポリエチレンテレフタレートフィルムを再ペレット化し使用した以外は、参考例と同様にして熱現像感光材料４３〜５１を作製した。
【０１８４】
この熱現像感光材料各試料を参考例と同様の方法で画像形成し、得られた露光・熱現像処理された画像の色調および未露光部色調および画像部色調を目視での官能評価により参考例と同じ基準で評価した。得られた結果を表５に示す。
【０１８５】
【表５】

【０１８６】
実施例５
参考例及び実施例１〜４において作製した熱現像感光材料から、表６に示す熱現像感光材料を下記の画像記録方法で画像露光した以外は、参考例と同様の自動現像機を用いて、１２２℃で１６秒熱現像処理し画像形成を行った。得られた各試料につき画像の干渉縞を下記の基準で官能評価と濃度測定（ΔＤ）により評価した。得られた結果を表６に示す。なお、露光量を参考例での保護層表面での露光エネルギーと同一となるように調整した。
【０１８７】
〈画像記録方法１〉
熱現像感光材料の保護層面側から、波長８２０ｎｍ半導体レーザを露光源とした露光機によりレーザ走査による露光を与えた。この際に、熱現像感光材料の露光面と露光レーザ光の角度を９０度に設定し、画像露光した。
【０１８８】
〈画像記録方法２〉
熱現像感光材料の保護層面側から、波長８２０ｎｍ半導体レーザを露光源とした露光機によりレーザ走査による露光を与えた。この際に、熱現像感光材料の露光面と露光レーザ光の角度を７０度として画像露光した。
【０１８９】
〈画像記録方法３〉
熱現像感光材料の保護層面側から、高周波重畳にて波長８００ｎｍ〜８２０ｎｍの縦マルチモード化された半導体レーザを露光源とした露光機によりレーザ走査による露光を与えた。この際に、熱現像感光材料の露光面と露光レーザ光の角度を９０度として画像露光した。
【０１９０】
〈画像記録方法４〉
熱現像感光材料の保護層面側から、２個の波長８２０ｎｍ半導体レーザを露光源とし、同時に発光させた２本のレーザ光をポリゴンミラーで偏向走査し、ｆθレンズを介して熱現像感光材料上に集光させるようにした露光機を用いてレーザ走査による露光を与えた。この際に、熱現像感光材料の露光面と露光レーザ光の角度を１本のレーザ光を８５度、他方を９５度として画像露光した。なお、各々のレーザ光の露光面でのエネルギー強度は同一とし、またエネルギー強度はそれぞれ画像記録方法１の強度の１／２とした。
【０１９１】
（官能評価）
透過濃度が１．８０±０．１５となるように露光・熱現像処理された画像を、輝度１００００カンデラ／ｍ²のシャーカステン上に試料を置き、干渉縞の発生の程度を以下に示すようにランク付けして、官能評価した。
【０１９２】
４：干渉縞が認められない。
３：ごく僅かに干渉縞が認められる。
【０１９３】
２：部分的にはっきりと干渉縞が認められる。
１：全面にはっきりと干渉縞が認められる。
【０１９４】
（濃度測定（ΔＤ））
スリット開口部を絞れる濃度計を用いて画像部の濃度を走査測定することにより、干渉縞パターンがはっきりしている場合には、明るい縞と暗い縞との間の透過濃度の差として定量的に評価することが出来る。そこで、透過濃度が１．８０±０．１５となるように露光・熱現像処理された画像を、マイクロデンシトメータ（コニカ（株）製、コニカマイクロデンシトメータＰＤＭ−７タイプＢＲ）で測定間隔２５μｍ、測定長さ２０ｍｍで５箇所測定（全測定点数４０００点）し、上記記載の官能評価を濃度の差ΔＤと関連づけした。ΔＤが小さいほど、干渉縞の発生がすくないことを表す。
【０１９５】
ΔＤ＝（測定点中最大濃度）−（測定点中最小濃度）
【０１９６】
【表６】

【０１９７】
【発明の効果】
熱現像感光材料の未露光部および画像部の色調が優れ、且つ支持体のリサイクル性に優れた熱現像感光材料およびその熱現像感光材料を用いた好適な画像記録方法を提供することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photothermographic material, a method for producing the photosensitive material, and an image recording method.
[0002]
[Prior art]
Conventionally, in the medical and printing plate making fields, waste liquids resulting from wet processing of image forming materials have been a problem in terms of workability. In recent years, the amount of waste processing liquids has been strongly reduced from the viewpoint of environmental conservation and space saving. It is desired.
[0003]
Therefore, there is a need for a technology related to photothermographic materials for photographic technology that can be efficiently exposed with a laser imager or laser image setter, and can form a clear black image with high resolution. Such photothermographic materials are disclosed, for example, in U.S. Pat. Nos. 3,152,904, 3,457,075 (D. Morgan and B. Shely) or D.M. H. “Thermally Processed Silver Systems” by Klosterboer (Imaging Processes and Materials) Nevlett 8th Edition, Sturge As described in Walworth, A. Shepp, 279, 1989), the support contains an organic silver salt, photosensitive silver halide grains, and a reducing agent. There are known heat-developable photosensitive materials. Since this photothermographic material does not use any solution processing chemicals, it is possible to provide a user with a simpler system that does not damage the environment.
[0004]
By the way, in a photothermographic material for medical use, a support colored in blue is often used. As such a blue colorant, molecularly dispersible organic dyes are widely used in order to ensure transparency.
[0005]
However, when the organic dye is kneaded at the time of forming the support, it is necessary to melt and knead it with the support forming resin, so that the dye itself is required to have high heat resistance. However, it may be kept at a high temperature for a long time due to troubles such as a manufacturing process. In such a case, the dye may be partially denatured by heat, and the color tone of the support may be changed. In addition, since the dye cannot be uniformly dispersed unless it is sufficiently melted and kneaded with the support forming resin, even if a predetermined amount of dye is added at the time of manufacture, the transmission density of the support is different, In some cases, a change in color tone due to partial aggregation was observed.
[0006]
On the other hand, in recent years, there has been a demand for recycling of the support from the viewpoint of environmental problems. However, there is a situation where wet-type photosensitive materials and photothermographic materials are mixed, and there is no support for blue-colored supports. Due to the presence of colored supports, the current situation is that sufficient measures have not yet been taken regarding the recycling of the supports.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is a photothermographic material excellent in color tone of unexposed areas and image areas, and excellent in recyclability of the support, and heat development thereof. An object is to provide a suitable image recording method using a photosensitive material.
[0008]
[Means for Solving the Problems]
  The object of the present invention is as follows.(1)~(8)Achieved by.Reference numerals 1 to 11 are items for reference.
  (1) In a photothermographic material in which an image forming layer containing at least an organic silver salt, a photosensitive silver halide, a reducing agent, and a protective layer are laminated in this order on a support, the surface opposite to the image forming layer A photothermographic material, comprising the same dye having λmax at 600 to 650 nm in the support, the image forming layer, and the backing layer.
  (2) The transmission density measured by the visual density of the support containing the dye was Ts2, and the transmission density measured by the visual density of the image forming layer containing the dye was measured by the visual density of Ti2, the backing layer containing the dye. The photothermographic material according to (1), wherein 0.10 ≦ Ts2 / (Ti2 + Tb2) ≦ 4.00 when the transmission density is Tb2.
  (3) In the photothermographic material in which at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on the support, the surface opposite to the image forming layer A photothermographic material comprising a backing layer, and the support, the image forming layer, the protective layer, and the backing layer containing the same dye having λmax of 600 to 650 nm.
  (4) The transmission density measured by the visual density of the support containing the dye was Ts3, the transmission density measured by the visual density of the image forming layer containing the dye was measured by the visual density of Ti3, and the protective layer containing the dye. The above (3), wherein the transmission density is Tp3 and the transmission density measured by the visual density of the backing layer containing the dye is Tb3, and 0.10 ≦ Ts3 / (Ti3 + Tp3 + Tb3) ≦ 4.00 The photothermographic material described in 1.
  (5) Scanning exposure using a laser in which the angle formed by the exposure surface and the laser beam is not substantially perpendicular to the photothermographic material described in any one of (1) to (4). An image recording method.
  (6) An image recording method, wherein the photothermographic material according to any one of (1) to (4) is subjected to scanning exposure using a vertical multilaser having a non-single exposure wavelength. .
  (7) An image recording method, wherein the photothermographic material according to any one of (1) to (4) is subjected to scanning exposure using two or more lasers.
  (8) The image recording method described in any one of (5) to (7) above, wherein the wavelength of the laser used for scanning exposure is in the range of 700 to 1200 nm.
[0009]
1. In a photothermographic material in which at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on a support, a backing layer is formed on the surface opposite to the image forming layer. A photothermographic material, comprising the same dye in the support and the backing layer.
[0010]
2. 2. The above-mentioned item 1, wherein the transmission density of the support containing the dye is Ts1, and the transmission density of the backing layer containing the dye is Tb1, 0.10 ≦ Ts1 / Tb1 ≦ 5.00. Photothermographic material.
[0011]
3. In a photothermographic material in which at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on a support, a backing layer is formed on the surface opposite to the image forming layer. A photothermographic material comprising the same dye in the support, the image forming layer and the backing layer.
[0012]
4). When the transmission density of the support containing the dye is Ts2, the transmission density of the image-forming layer containing the dye is Ti2, and the transmission density of the backing layer containing the dye is Tb2, 0.10 ≦ Ts2 / (Ti2 + Tb2) 4. The photothermographic material according to 3 above, wherein ≦ 4.00.
[0013]
5. In a photothermographic material in which at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on a support, a backing layer is formed on the surface opposite to the image forming layer. A photothermographic material comprising the same dye in the support, the image forming layer, the protective layer and the backing layer.
[0014]
6). The transmission density of the support containing the dye was Ts3, the transmission density of the image-forming layer containing the dye was Ti3, the transmission density of the protective layer containing the dye was Tp3, and the transmission density of the backing layer containing the dye was Tb3. 5. The photothermographic material according to 5, wherein 0.10 ≦ Ts3 / (Ti3 + Tp3 + Tb3) ≦ 4.00.
[0015]
7. 7. The photothermographic material according to any one of 1 to 6, wherein the dye has [lambda] max at 600 to 650 nm.
[0016]
8). The photothermographic material described in any one of 1 to 7 above is subjected to scanning exposure using a laser in which an angle formed by an exposure surface and a laser beam is not substantially perpendicular. Image recording method.
[0017]
9. 8. An image recording method, wherein the photothermographic material described in any one of 1 to 7 above is subjected to scanning exposure using a vertical multi-laser having a single exposure wavelength.
[0018]
10. 8. An image recording method, wherein the photothermographic material described in any one of 1 to 7 above is subjected to scanning exposure using two or more lasers.
[0019]
11. The image recording method described in any one of 8 to 10 above, wherein the wavelength of the laser used for scanning exposure is in the range of 700 to 1200 nm.
[0020]
The photothermographic material of the present invention will be described below.
In the photothermographic material of the present invention, at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on a support, and further opposite to the image forming layer. It is composed of a backing layer installed on the surface.
[0021]
Among them, in the present invention, the same dye as the dye contained in the support is contained in the specific layer, the transmission density of the support colored with the dye, and the transmission density of the specific layer colored with the dye. There are three types of modes depending on the position of the layer to be colored with the dye. Each mode will be described in detail below.
[0022]
  preferableAs an embodiment, the same dye is contained in the support and the backing layer forming the photothermographic material.
[0023]
  preferableExamples of the resin for forming the support used in the embodiment include acrylic resin, polyester, polycarbonate, polyarylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, nylon, aromatic polyamide, polyether ether ketone, polysulfone, poly Examples include resin films such as ether sulfone, polyimide, polyether imide, and triacetyl cellulose, and resin films obtained by laminating two or more layers of the resin.
[0024]
In the image recording method described below, the support according to the present invention is preferably developed in the form of a latent image and then developed with heat to form an image. As the resin, polyester, polycarbonate, polyarylate, polyether ether ketone, and triacetyl cellulose are preferable, and polyester that has been biaxially stretched and annealed therein is more preferable from the viewpoint of versatility and / or cost.
[0025]
The polyester described above will be described in more detail. The polyester referred to here is a polymer compound having an ester bond in the molecular main chain, and is a polymer obtained by condensation polymerization from a diol and a dicarboxylic acid. Dicarboxylic acids are typified by terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid and the like, and diols are ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane. It is represented by dimethanol. In the present invention, in particular, polyethylene terephthalate (PET) or a copolymer thereof, polybutylene naphthalate (PBN) or a copolymer thereof, polybutylene terephthalate (PBT) or a copolymer thereof, and polyethylene naphthalate (PEN) and Such copolymers are preferably used. The repeating unit of these polyesters is preferably 100 or more, particularly 150 or more, and the intrinsic viscosity is preferably 0.6 dl / g or more, more preferably 0.7 d1 / g or more. In such cases, the film-forming stability is excellent and preferable. Of course, these polyesters include known additives such as lubricants, stabilizers, antioxidants, viscosity modifiers, antistatic agents, colorants, and A pigment or the like can be arbitrarily blended.
[0026]
The thickness of the support is usually about 120 to 500 μm, more preferably 150 to 250 μm.
[0027]
Since the present invention is used for medical imaging, the support contains a blue dye.
As such dyes, Disperse dyes, Cationic dyes, Basic dyes, Acid dyes, Reactive dyes, Direct dyes, Vat dyes, Azoic dyes, Modern dyes, Union dyes, Solvent dyes, etc. may be appropriately selected and used. Among these, Solvent dyes are preferable from the viewpoints of uniform dispersibility during melt kneading at the time of forming the support and dye solubility when preparing a coating liquid for forming a backing layer described later. In order to prevent sublimation during melt-kneading and to reduce dye alteration during kneading as much as possible, a thermal stability of 250 ° C. or higher is preferable, and a resin used as a support is extruded. When it is necessary to raise the temperature of the extruder to 300 ° C., a temperature of 280 ° C. or higher is more preferable.
[0028]
The thermal stability here can be determined by the following method. That is, after dissolving and kneading the dye for 30 minutes in polystyrene (number average molecular weight 100,000) heat-melted at 200 ± 20 ° C. so that the dye concentration becomes 1%, the test piece 1 (reference product) having a thickness of 3 mm is formed by injection molding. ). Separately, the same dye was dissolved and kneaded in polystyrene that was heat-melted at 250 ° C. so that the dye concentration would be 1%, and the test piece 2 having a thickness of 3 mm was similarly produced by injection molding. The spectral absorptions 1 and 2 are measured, the absorbances Ab1 and Ab2 at λmax are obtained, and the ratio is calculated as Ab2 / Ab1. A dye having this value of 0.95 or more was regarded as having thermal stability at 250 ° C.
[0029]
Specific examples of Solvent dyes that are stable even at 280 ° C. or higher as described above are described in detail in Color Index. I. Solvent Blue 80, C.I. I. Solvent Blue 82, C.I. I. Solvent Blue 83, C.I. I. Solvent Blue 84, C.I. I. Solvent Blue 85, C.I. I. Solvent Blue 86, C.I. I. Solvent Blue 87, C.I. I. Solvent Blue 90, C.I. I. Solvent Blue 91, C.I. I. Solvent Blue 92, C.I. I. Solvent Blue 93, C.I. I. Solvent Blue 94, C.I. I. Solvent Blue 95, C.I. I. Solvent Blue 97, C.I. I. Solvent Blue 101, C.I. I. Solvent Blue 102, C.I. I. Solvent Blue 104, C.I. I. Solvent Blue 105, C.I. I. Solvent Blue 106, C.I. I. Solvent Blue 108, C.I. I. Solvent Blue 109, C.I. I. SolventBlue 110, C.I. I. Solvent Blue 121, C.I. I. Solvent Blue 130, C.I. I. Solvent Blue 132 and the like. These may be used alone or in combination of two or more dyes.
[0030]
Moreover, the dye which has absorption (lambda) max in 600-650 nm is more preferable from the objective of coloring in blue among the above-mentioned dyes.
[0031]
  preferableThe backing layer of the embodiment is composed of a binder resin for holding the dye and various additives added as necessary, in addition to the same dye as the support which is an essential component.
[0032]
As specific dyes, the dyes used in the aforementioned support can be appropriately selected and used. In addition, when using multiple types of dye used for a support body, the dye added to a backing layer uses the same kind of dye as what was used for the support body, and the ratio of dye is also set to the same.
[0033]
In addition, as a binder resin for holding a dye, a conventionally used transparent or translucent binder resin can be selected and used as appropriate, and as such a binder resin, for example, polyvinyl formal, Polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, cellulose resins such as nitrocellulose and cellulose acetate butyrate, styrene resins such as polystyrene, styrene-acrylonitrile copolymer, styrene-acrylonitrile-acrylic rubber copolymer, poly Examples include vinyl chloride resins such as vinyl chloride and vinyl chloride-vinyl acetate copolymer, acrylic resins such as polymethyl methacrylate, polyester, polyurethane, polycarbonate, polyarylate, epoxy resin, phenoxy resin, etc. Are further may be used epoxy group-containing compound was assumed to be cured with active energy ray, an acrylic group-containing compound such as a layer forming binder resin. In addition, these binder resins may be used alone or in combination of two or more resins.
[0034]
Moreover, when the above-mentioned binder resin has a hydroxyl group, a crosslinking agent such as a metal alkoxide having a plurality of metal alkoxide moieties in the molecule such as a conventionally known polyfunctional isocyanate compound, alkoxysilane compound, alkoxytitanium compound, etc. It may be added and cross-linked.
[0035]
As other various additives, it is preferable to contain a filler for the purpose of preventing pickup failure in the apparatus and ensuring transportability, and the content when the filler is added is 0.05 in the backing layer forming composition. It is preferable to contain -30 mass%.
[0036]
Such fillers include SiO₂TiO₂, BaSO_Four, ZnS, MgCO_Three, CaCO_Three, ZnO, CuO, CaO, WS₂, MoS₂, MgO, SnO₂, Al₂O_Three, Α-Fe₂O_Three, Α-FeO₂H, SiC, CeO₂, Y₂O_Three, ZrO₂, MoC, BC, WC, BN, SiN, andalusite, sillimanite, mullite, aluminum borate, titanium carbide, corundum, artificial diamond, garnet, garnet, quartzite, triboli, diatomaceous earth, smectite, dolomite, ITO, ATO, etc. Inorganic compounds, polyethylene resin particles, fluororesin particles, guanamine resin particles, acrylic resin particles, silicon resin particles, melamine resin particles, and other organic compounds can be used. Further, the property may be nonporous or porous. In addition, it is preferable that the average particle diameter of a filler is 0.01 micrometer-20 micrometers (in the case of a needle shape, it is a short axis diameter), More preferably, they are 0.05 micrometer-10.0 micrometers.
[0037]
Furthermore, the backing layer may contain a lubricant and an antistatic agent in order to improve slipperiness and chargeability. Examples of such lubricants include fatty acids, fatty acid esters, fatty acid amides, polyoxyethylene, polyoxyethylene, Examples thereof include oxypropylene, (modified) silicone oil, (modified) silicone resin, (modified) fluorine compound, (modified) fluorine resin, carbon fluoride, and wax. Antistatic agents include cationic surfactants, anionic surfactants, nonionic surfactants, polymer antistatic agents, metal oxides or conductive polymers, etc. Nipposha, p. 875-876 etc., the compound described in US Patent No. 5,244,773 columns 14-20, etc. can be mentioned. Furthermore, for the purpose of preventing halation, a compound having absorption in the oscillation wavelength region of a laser described in detail in an image recording method described later may be contained as an antihalation agent.
[0038]
The thickness of the backing layer is usually about 0.5 to 10 μm, and more preferably 1.0 to 8 μm. Further, the backing layer may be formed of a single layer or a plurality of layers having different compositions.
[0039]
Furthermore, an antistatic layer is provided between the support and the backing layer for the purpose of preventing the antistatic, and the support surface on which the backing layer is laminated in order to improve adhesion and applicability, as long as the effects of the present invention are not impaired. The surface may be modified using a known surface modification technique such as corona discharge treatment, plasma treatment, anchor coating treatment, or the like.
[0040]
  preferableIn the aspect, when the transmission density of the support containing the dye described above is Ts1, and the transmission density of the backing layer containing the dye is Tb2, the ratio of Ts1 and Tb1 is 0.05 ≦ Ts1 / Tb1 ≦ 5. In the range of .00Is preferred. In addition, the transmission density here is a visual density measured by a transmission densitometer (manufactured by Konica Corporation, PDA-65: three digits after the decimal point).
[0041]
In addition to the dye, in addition to the dye, various additives that are added as necessary, as well as the binder resin in addition to the dye in the backing layer, are involved in the absorption of the entire visible light. Various additives added as needed are mentioned.
[0042]
In general, it cannot be generally defined by the resin or film forming process for forming the support, but the transmission density of the support is usually 0.004 to 0.007 when the film is formed with only the resin. In addition, the transmission density of the backing layer cannot be generally defined by the type of binder resin of the layer, the preparation method of the coating liquid, and the coating / drying method, but is usually in the range of 0.001 to 0.005. .
[0043]
  In addition, since the combined transmission density of the support and the backing layer is in the range of 0.150 to 0.175,preferableThe transmission density of the support colored blue with the dye in the embodiment is 0.014 to 0.146.
[0044]
In order to suppress the deterioration of the dye during the formation of the support, that is, the melt kneading, which is one object of the present invention, it is preferable to suppress the contribution ratio of the dye as low as possible. However, considering the recyclability of the support from the aspect of environmental problems in recent years, since the blue-colored support currently used is more than the clear support containing no dye, the permeation density is 0. In order to suppress the deterioration of the dye during melt kneading as much as possible, the ratio of the transmission density of the support to the total transmission density should be 80% or less, and more preferably 70% or less. Is preferred.
[0045]
Next, an image forming layer containing an organic silver salt, photosensitive silver halide, and a reducing agent as essential components will be described in detail.
[0046]
The photosensitive silver halide, which is an essential component in the image forming layer of the present invention, preferably has a small average grain size in order to suppress white turbidity after image formation and to obtain good image quality, and the average grain size is 0. 0.1 μm or less, more preferably 0.01 μm to 0.1 μm, and particularly preferably 0.02 μm to 0.08 μm. The particle size here refers to the diameter (equivalent circle diameter) of a circle having the same area as each particle image observed with an electron microscope. The particle size can be obtained, for example, by magnifying the particle with an electron microscope from 10,000 times to 70,000 times and measuring the particle diameter on the print or the projected area (the number of measured particles is There are 1000 or more indiscriminately). The silver halide is preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. The particles are more preferably 30% or less, and particularly preferably 20% or less.
[0047]
Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100
The shape of the photosensitive silver halide grains is not particularly limited, but the ratio occupied by the Miller index [100] plane is preferably high, and this ratio is 50% or more, further 70% or more, particularly 80% or more. Preferably there is. The ratio of the Miller index [100] plane is determined by T.T. based on the adsorption dependency of the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. 29, 165 (1985).
[0048]
Another preferred form of photosensitive silver halide is tabular grain. The tabular grains referred to here are those having an aspect ratio = r / h of 3 or more when the square root of the projected area is the grain size r μm and the thickness in the vertical direction is h μm. Among them, the aspect ratio is preferably 3 or more and 50 or less. The particle size is preferably 0.1 μm or less, more preferably 0.01 μm to 0.08 μm. These are described in US Pat. Nos. 5,264,337, 5,314,798, 5,320,958, etc., and the desired tabular grains can be easily obtained.
[0049]
The photosensitive halogen composition is not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide. The emulsion used in the present invention is P.I. Chifie et Physique Photographic (published by Paul Montel, 1967) by Glafkides. F. Duffin's Photographic Emission Chemistry (published by The Focal Press, 1966), V.C. L. It can be prepared using a method described in Making and Coating Photographic Emulsion (published by The Focal Press, 1964) by Zelikman et al.
[0050]
The photosensitive silver halide according to the present invention preferably contains a metal ion belonging to Groups 6 to 11 of the periodic table. As the metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable.
[0051]
These metal ions can be introduced into the silver halide in the form of metal complexes or metal complex ions. As these metal complex ions, hexacoordinate metal complex ions represented by the following general formula are preferable.
[0052]
General formula [ML₆]^m
In the formula, M represents a transition metal selected from Group 6 to 11 elements of the periodic table, L represents a ligand, and m represents 0,-, 2-, 3- or 4-. Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aco. A ligand, nitrosyl, thionitrosyl and the like can be mentioned, and ako, nitrosyl, thionitrosyl and the like are preferable. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.
[0053]
M is preferably rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) or osmium (Os). Specific examples of transition metal complex ions containing these include [RhCl₆]^3-, [RuCl₆]^3-, [ReCl₆]^3-, [RuBr₆]^3-, [OsCl₆]^3-, [IrCl₆]^Four-, [Ru (NO) Cl_Five]^2-, [RuBr_Four(H₂O)]^2-, [Ru (NO) (H₂O) Cl_Four]^-, [RhCl_Five(H₂O)]^2-, [Re (NO) Cl_Five]^2-, [Re (NO) (CN)_Five]^2-, [Re (NO) Cl (CN)_Four]^2-, [Rh (NO)₂Cl_Four]^-, [Rh (NO) (H₂O) Cl_Four]^-, [Ru (NO) (CN)_Five]^2-, [Fe (CN)₆]^3-, [Rh (NS) Cl_Five]^2-, [Os (NO) Cl_Five]^2-, [Cr (NO) Cl_Five]^2-, [Re (NO) Cl_Five]^-, [Os (NS) Cl_Four(TeCN)]^2-, [Ru (NS) Cl_Five]^2-, [Re (NS) Cl_Four(SeCN)]^2-, [Os (NS) Cl (SCN)_Four]^2-, [Ir (NO) Cl_Five]^2-, [Ir (NS) Cl_Five]^2-Etc.
[0054]
One kind of metal ion or metal complex ion described above may be used, or two or more kinds of the same kind of metal and different kinds of metals may be used in combination. The content of these metal ions or metal complex ions is generally 1 × 10 5 per mole of silver halide.^-9~ 1x10^-2Molar is suitable, preferably 1 × 10^-8~ 1x10^-FourIs a mole.
[0055]
The compounds providing these metals are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening, chemical sensitization Although it may be added at any stage before or after, it is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably nucleation. Add in stages.
[0056]
In addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains. JP-A-63-29603, JP-A-2-306236, 3 As described in JP-A Nos. 167545, 4-76534, 6-110146, 5-273683, etc., the particles can be contained with a distribution. Preferably, a distribution can be provided inside the particles.
[0057]
These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble silver salt solution or water-soluble halide solution during particle formation, or the silver salt solution and the halide solution are mixed simultaneously. When adding a third aqueous solution, a method of preparing silver halide grains by a method of simultaneous mixing of three liquids, a method of introducing an aqueous solution of a required amount of a metal compound into a reaction vessel during grain formation, or a silver halide preparation There is a method of adding and dissolving another silver halide grain which has been previously doped with metal ions or complex ions. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble halide solution.
[0058]
When added to the particle surface, a necessary amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particle, during or after physical ripening, or at the time of chemical ripening.
[0059]
In the present invention, the photosensitive silver halide grains may or may not be desalted after grain formation. However, when desalting is performed, methods known in the art such as a noodle method and a flocculation method are used. It can be desalted by washing with water.
[0060]
The silver halide grains used in the present invention are preferably chemically sensitized. As a preferable chemical sensitization method, a sulfur sensitization method, a selenium sensitization method and a tellurium sensitization method can be used as is well known in the art. Further, noble metal sensitization methods such as gold compounds, platinum, palladium, iridium compounds and reduction sensitization methods can be used.
[0061]
Known compounds can be used as the compounds preferably used in the above-described sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, and compounds described in JP-A-7-128768 can be used. . Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Te. A compound having a bond, tellurocarboxylic acid salts, Te-organyltellurocarboxylic acid esters, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond, Te heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium and the like can be used.
[0062]
Examples of the compound preferably used for the noble metal sensitization include chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, US Pat. No. 2,448,060, and British Patent 618,061. Etc. can preferably be used.
[0063]
Specific examples of compounds used for the reduction sensitization include ascorbic acid and thiourea dioxide, such as stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, and polyamine compounds. Can do. Further, reduction sensitization can be performed by ripening the emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower. Further, reduction sensitization can be performed by introducing a single addition portion of silver ions during grain formation.
[0064]
The organic silver salt contained in the image forming layer of the present invention is a reducible silver source, and is an organic acid containing a reducible silver ion source. Examples of the organic acid used in the present invention include aliphatic carboxylic acid, carbocyclic carboxylic acid, heterocyclic carboxylic acid, heterocyclic compound and the like, but particularly long chain (10-30, preferably 15-25). The aliphatic carboxylic acid having the number of carbon atoms) and the heterocyclic carboxylic acid having a nitrogen-containing heterocyclic ring are preferably used. Also useful are organic silver salt complexes in which the ligand has a total stability constant for silver ions of 4.0-10.0.
[0065]
Examples of such organic acid silver salts are described in Research Disclosure Nos. 17029 and 29963. Of these, silver salts of fatty acids are preferably used, and silver behenate, silver arachidate, and silver stearate are particularly preferably used.
[0066]
The aforementioned organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound that forms a salt with silver (or complex formation), and a normal mixing method, a reverse mixing method, a simultaneous mixing method, and the like are preferably used. . It is also possible to use a controlled double jet method as described in JP-A-9-127643.
[0067]
In the present invention, the organic silver salt preferably has an average particle size of 1 μm or less and is monodispersed. The average particle diameter of the organic silver salt refers to the diameter when a sphere equivalent to the volume of the organic silver salt particle is considered when the organic silver salt particle is, for example, a spherical, rod-like, or tabular particle. The average particle diameter is preferably 0.01 μm to 0.8 μm, particularly preferably 0.05 μm to 0.5 μm. Moreover, monodispersion is synonymous with the case of silver halide, Preferably monodispersion degree is 1 to 30%. In the present invention, the organic silver salt is more preferably monodisperse particles having an average particle size of 1 μm or less, and an image having a high density can be obtained by setting the content within this range. Further, the organic silver salt preferably has tabular grains having 60% or more of the total organic silver. In the present invention, the tabular grains are those having an average grain diameter / thickness ratio, that is, an aspect ratio (abbreviated as AR) represented by the following formula of 3 or more.
[0068]
AR = average particle diameter (μm) / thickness (μm)
Such organic silver salt particles are preferably preliminarily dispersed together with a binder or a surfactant as necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. For the preliminary dispersion, a general stirrer such as an anchor type or a propeller type, a high-speed rotating centrifugal radiation type stirrer (dissolver), or a high-speed rotating shear type stirrer (homomixer) can be used. In addition, as the media dispersing machine, a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill that is a medium agitation mill, an attritor, and other basket mills can be used, and a wall as a high-pressure homogenizer. Various types can be used, such as a type that collides with a plug or the like, a type in which liquids are collided at a high speed after dividing the liquid, and a type in which a thin orifice is passed.
[0069]
In the apparatus used when dispersing the organic silver particles used in the present invention, ceramics such as zirconia, alumina, silicon nitride, boron nitride, or diamond is used as the material of the member in contact with the organic silver salt particles. It is particularly preferable to use zirconia.
[0070]
The organic silver salt particles used in the present invention preferably contain 0.01 mg to 0.5 mg of Zr per gram of silver, and particularly preferably contain 0.01 mg to 0.3 mg of Zr. Optimizing the binder concentration, pre-dispersing method, disperser operating conditions, number of times of dispersion, and the like at the time of the dispersion is very preferable as a method for obtaining organic silver salt particles used in the present invention.
[0071]
As the reducing agent contained in the image forming layer of the present invention, those known in the art can be used, for example, phenols, polyphenols having two or more phenol groups, naphthols, bisphenols. Naphthols, polyhydroxybenzenes having 2 or more hydroxyl groups, polyhydroxynaphthalenes having 2 or more hydroxyl groups, ascorbic acids, 3-pyrazolidones, pyrazolin-5-ones, pyrazolines, phenylenediamines, hydroxyl Examples include amines, hydroquinone monoethers, hydrooxamic acids, hydrazides, amide oximes, and N-hydroxyureas.
[0072]
Among the reducing agents described above, when an aliphatic carboxylic acid silver salt is used as the organic silver salt, preferred reducing agents include polyphenols in which two or more phenol groups are linked by an alkylene group or sulfur, particularly phenol groups. Phenol in which an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a t-butyl group, a cyclohexyl group, etc.) or an acyl group (for example, an acetyl group, a propionyl group, etc.) is substituted at at least one position adjacent to the hydroxy substitution position Polyphenols in which two or more of the groups are linked by an alkylene group or sulfur, such as 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane, 1,1-bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, 1,1-bis (2-hydroxy-3) 5-di-t-butylphenyl) methane, 2-hydroxy-3-t-butyl-5-methylphenyl- (2-hydroxy-5-methylphenyl) methane, 6,6'-benzylidene-bis (2,4 -Di-t-butylphenol), 6,6'-benzylidene-bis (2-t-butyl-4-methylphenol), 6,6'-benzylidene-bis (2,4-dimethylphenol), 1,1- Bis (2-hydroxy-3,5-dimethylphenyl) -2-methylpropane, 1,1,5,5-tetrakis (2-hydroxy-3,5-dimethylphenyl) -2,4-ethylpentane, 2, U.S. Pat. Nos. 3,589 such as 2-bis (4-hydroxy-3,5-dimethylphenyl) propane and 2,2-bis (4-hydroxy-3,5-di-t-butylphenyl) propane No. 903, No. 4,021,249 or British Patent No. 1,486,148 and JP-A-51-51933, No. 50-36110, No. 50-116023, No. 52-84727. Or polyphenol compounds described in JP-B-51-35727, bisnaphthols described in US Pat. No. 3,672,904, such as 2,2′-dihydroxy-1,1′-binaphthyl, 6,6'-dibromo-2,2'-dihydroxy-1,1'-binaphthyl, 6,6'-dinitro-2,2'-dihydroxy-1,1'-binaphthyl, bis (2-hydroxy-1- Naphthyl) methane, 4,4'-dimethoxy-1,1'-dihydroxy-2,2'-binaphthyl and the like, and further described in U.S. Pat. No. 3,801,321. Examples of such sulfonamidophenols or sulfonamidonaphthols include 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfonamidophenol, 4-benzenesulfonamidonaphthol and the like. be able to.
[0073]
The amount of the reducing agent contained in the image-forming layer of the present invention varies depending on the type of organic silver salt, reducing agent, and other additives, but is generally 0.05 mol to 10 mol per mol of organic silver salt. The molar amount is preferably 0.1 to 3 mol. In addition, within the range of this amount, two or more of the reducing agents described above may be used in combination.
[0074]
Furthermore, in the present invention, a binder resin is used for the image forming layer in order to retain the above-described essential components. As such a binder resin, the binder resin described in detail in the above backing layer can be selected and used in a timely manner as long as the object of the present invention is not impaired. However, since it is necessary to disperse and hold the organic silver salt compound described above with a binder resin, a resin having a hydroxyl group, a carboxyl group or a salt thereof, or a sulfonic acid or a salt thereof in the molecule is preferable, and a polyvinyl acetal resin, cellulose Resins, phenoxy resins, and modified vinyl chloride resins, modified polyesters, modified polyurethanes, modified epoxy resins, modified acrylic resins, and the like having the above functional groups introduced, are used alone. Alternatively, two or more resins may be used in combination.
[0075]
Further, in the image forming layer of the present invention, an antifoggant, a toning agent, a sensitizing dye, and a substance exhibiting supersensitization (hereinafter referred to as supersensitizer) in addition to the essential components and binder resin described above. Various additives such as “abbreviated”) may be added.
[0076]
Such antifogging agents are disclosed in JP-B-54-44212, JP-A-51-9694, JP-A-55-140833, US Pat. Nos. 3,874,946 and 4,756,999. A compound as disclosed, -C (X₁) (X₂) (X_Three) (Where X₁And X₂Represents a halogen atom and X_ThreeRepresents a hydrogen or halogen atom), heterocyclic compounds having at least one substituent represented by JP-A-9-288328, JP-A-9-90550, US Pat. No. 5,028,523 and European Patent 600 , 587, 605, 981, 631, 176, and the like, and tribromoacetyl compounds exemplified below may be used alone or in combination of two or more.
[0077]
[Chemical 1]

[0078]
[Chemical 2]

[0079]
Toning agents added for the purpose of improving the silver tone after development include imides (for example, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (for example, succinimide, 3-phenyl-2-pyrazolin) -5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione); naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, hexamine trifluoroacetate of cobalt), Mercaptans (eg, 3-mercapto-1,2,4-triazole); N- (aminomethyl) aryl dicarboximides (eg, N- (dimethylaminomethyl) phthalimide); blocked pyrazoles (eg, N, N′-hexamethylenebis (1-carbamoy -3,5-dimethylpyrazole)), isothiuronium derivatives and certain photobleaching combinations (eg 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2 -(Tribromomethylsulfonyl) benzothiazole combination); Merocyanine dyes (eg 3-ethyl-5-((3-ethyl-2-benzothiazolinylidene) -1-methylethylidene) -2-thio-2 , 4-oxazolidinedione); phthalazinone, phthalazinone derivatives or metal salts of these derivatives (eg, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3 -Dihydro-1,4-phthalazinedione); phthalazinone and sulfur Combinations of phosphonic acid derivatives (eg 6-chlorophthalazinone and sodium benzenesulfinate or 8-methylphthalazinone and sodium p-trisulfonate); combinations of phthalazine and phthalic acid; phthalazine (including phthalazine adduct) ) And maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and anhydrides thereof (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride) Quinazolinediones, benzoxazines, naltoxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione); pyrimidines And asymmetric triazines (eg 2,4 -Dihydroxypyrimidine) and tetraazapentalene derivatives (for example, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene). Preferable toning agents include phthalazinone and phthalazine.
[0080]
In addition, as long as the objective of this invention is not impaired, you may add a color toner to the protective layer mentioned later.
[0081]
As the sensitizing dye, for example, for an argon ion laser light source, JP-A-60-162247, JP-A-2-48635, US Pat. No. 2,161,331, West German Patent 936,071, For the simple merocyanines and helium neon laser light sources described in Japanese Patent Application No. 3-189532, etc., trinuclear cyanines disclosed in JP-A Nos. 50-62425, 54-18726, and 59-102229 are disclosed. For dyes, merocyanines described in Japanese Patent Application No. 6-103272, LED light sources and infrared semiconductor laser light sources, Japanese Patent Publication Nos. 48-42172, 51-9609, 55-39818, JP JP-A-5-284343 and thiacarbocyanines described in JP-A-2-105135 and infrared semiconductor laser light sources No. -191032, Tricarbocyanines described in JP-A-60-80841, JP-A-59-192242, JP-A-3-67242, general formulas (IIIa) and (IIIb) described in 4- Dicarbocyanines and the like containing a quinoline nucleus are advantageously selected. Further, when the wavelength of the infrared laser light source is 750 nm or more, more preferably 800 nm or more, in order to cope with the laser in such a wavelength range, JP-A-4-18239, JP-A-5-341432, JP-B-6-6 Nos. 52387, 3-10931, U.S. Pat. No. 5,441,866, and JP-A-7-13295 are preferably used.
[0082]
Supersensitizers are described in RD17643, JP-B-9-25500, JP-A-43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. A compound can be appropriately selected and used. In the present invention, the heteroaromatic mercapto compound represented by the following general formula (M), which is a general formula (Ma) that substantially produces the above heteroaromatic mercapto compound, The disulfide compounds represented can be used.
[0083]
Formula (M) Ar-SM
Formula (Ma) Ar-SS-Ar
In general formula (M), M represents a hydrogen atom or an alkali metal atom, and Ar represents a heteroaromatic ring or condensed heteroaromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. The heteroaromatic ring is preferably benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, pyrazine, Pyridine, purine, quinoline or quinazoline. Ar in the general formula (Ma) has the same meaning as in the general formula (M).
[0084]
The heteroaromatic ring includes, for example, a halogen atom (for example, Cl, Br, I), a hydroxy group, an amino group, a carboxyl group, and an alkyl group (for example, one or more carbon atoms, preferably 1 to 4 carbon atoms). And a substituent selected from the group consisting of an alkoxy group (for example, one having 1 or more carbon atoms, preferably 1 to 4 carbon atoms).
[0085]
Furthermore, in the present invention, in order to achieve high sensitivity, it is more preferable to use the following thyronium compound as a supersensitizer.
[0086]
[Chemical Formula 3]

[0087]
[Formula 4]

[0088]
The supersensitizer is preferably used in an emulsion layer containing an organic silver salt and silver halide grains in the range of 0.001 to 1.0 mol per mol of silver, particularly 0.01 to 0 per mol of silver. The range is preferably 5 mol.
[0089]
The photosensitive layer of the present invention can contain a macrocyclic compound containing a hetero atom. A 9-membered or larger macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a heteroatom is preferred, a 12-24 membered ring is more preferred, and a 15-21 membered ring is still more preferred. is there.
[0090]
Representative compounds include crown ethers and C.I. J. et al. It was synthesized by Pederson in 1967 and has been synthesized many times since its unique report. These compounds are C.I. J. et al. Pederson, Journal of American chemical society vol, 86 (2495), 7017-7036 (1967), G.P. W. Gokel, S.M. H, Korzenowski, Macrocyclic polyethr synthesis, Springer-Vergal, (1982) and the like.
[0091]
In addition to the additives described above, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids and the like may be used in the image forming layer of the present invention. As these additives, the compounds described in Research Disclosure Item 17029 (June 1978, p. 9-15) can be appropriately selected and used within a range not impairing the object of the present invention.
[0092]
In addition, when the binder resin of the image forming layer has active hydrogen, cross-linking such as metal alkoxide having a plurality of metal alkoxide moieties in the molecule such as conventionally known polyfunctional isocyanate compounds, alkoxysilane compounds, and alkoxytitanium compounds. An agent may be added to improve the film strength.
[0093]
In the present invention, the image forming layer may be a single layer or a plurality of layers having the same or different compositions. The film thickness of the image forming layer is usually 10 to 30 μm.
[0094]
  preferableThe protective layer used in the photothermographic material of the aspect is composed of the binder resin described in the above-mentioned backing layer and / or image forming layer and an additive added as necessary, and the binder resin of the protective layer is a backing layer. The binder resin described in the layer and / or the image forming layer can be appropriately selected and used.
[0095]
As an additive to be added to the protective layer, it is preferable to contain a filler for the purpose of ensuring damage prevention and transportability of the image after heat development, and the content when the filler is added is in the layer forming composition. It is preferable to contain 0.05-30 mass%.
[0096]
As the filler used in the present invention, a filler used in the backing layer can be selected and used as appropriate.
[0097]
In addition, the protective layer may contain a lubricant and an antistatic agent in order to improve slipperiness and chargeability. As these compounds, a lubricant and an antistatic agent used in the backing layer are selected as appropriate. Can be used.
[0098]
Further, as in the case of the backing layer and the image forming layer, when the binder resin of the protective layer has a hydroxyl group or active hydrogen within the range not impairing the object of the present invention, a conventionally known polyfunctional isocyanate compound or alkoxysilane compound is used. Further, a film strength may be improved by adding a crosslinking agent such as a metal alkoxide having a plurality of metal alkoxide moieties in the molecule such as an alkoxytitanium compound.
[0099]
The amount of these additives added is preferably about 0.01 to 20% by mass, more preferably 0.05 to 10% by mass of the protective layer forming component.
[0100]
In the present invention, the protective layer may be a single layer or may be composed of a plurality of layers having the same or different composition. In addition, the film thickness of a protective layer is 1.0-5.0 micrometers normally.
[0101]
In the present invention, in addition to the above-mentioned image forming layer, support and protective layer, an intermediate layer may be provided in order to improve film attachment between the support and the image forming layer, and the thickness of the intermediate layer in the case of installation Is usually 0.05 to 2.0 μm.
[0102]
Incidentally, since an image signal handled by an imager used in image exposure described later is a digital signal, it is possible to perform image exposure as a normal image or a reverse image when viewed from the image forming layer side. In other words, when observing the photothermographic material after heat development on the Schaukasten, it can be observed from the image forming surface side or from the backing layer surface.
[0103]
  on the other hand,preferableIn the embodiment, the density per unit film thickness of each layer of the dye contained in the support and the backing layer is higher in the backing layer. Therefore, depending on whether or not the Schaukasten surface and the backing layer surface face each other, there may be a slight difference in color depending on the person who observes. Many cases appear. This is considered to be because the backing layer having a high dye concentration per unit film thickness is located closest to the observer, but the clear cause is not known.
[0104]
  In order to solve these problems, the first aspect of the present invention.1In the present invention, the same dye is contained in the support, backing layer and image forming layer forming the photothermographic material, and the support, backing layer and image forming layer are described in the first embodiment. It can be composed of a composition. Further, the dye added as an essential component to the backing layer and the image forming layer refers to the dye described in detail in the description of the support of the first aspect, and if the dye is the same as the dye added in the support There is no restriction in particular, and it can be used.
[0105]
When a plurality of dyes used for the support are used, the dye added to the backing layer and the image forming layer is the same dye used for the support, and the mass ratio of the dye is set to be the same. .
[0106]
  In addition1Aspect ofInWhen the transmission density of the support containing the dye is Ts2, the transmission density of the image-forming layer containing the dye is Ti2, and the transmission density of the backing layer containing the dye is Tb2, the relationship between Ts2, Ti2 and Tb2 is 0.10 ≦ Ts2 / (Ti2 + Tb2) ≦ 4.00TheTi2 and Tb2 are values larger than 0.00, but are practically values not exceeding 0.120.
[0107]
  By the relationship between Ts2, Ti2 and Tb2 being 0.10 ≦ Ts2 / (Ti2 + Tb2) ≦ 4.00,preferableAs described in the embodiment, it is possible to reduce dye deterioration during film formation of the support.
[0108]
  First1In this aspect, it is essential that Ti2 and Tb2 are not 0.00, and it is usually preferable that the value of Ti2 is 0.020 or more. Ti2 is preferably 0.200 or less, and practically within 0.120. The ratio between Ti2 and Tb2 is preferably 0.07 ≦ Tb2 / Ti2 ≦ 7.18, and more preferably 0.10 ≦ Tb2 / Ti2 ≦ 5.00.
[0109]
  First of the present invention2As an aspect of the invention, the support, image forming layer, protective layer and backing layer forming the photothermographic material are characterized by containing the same dye, and the support, image forming layer, protective layer and backing layer arepreferableIt can be comprised with the composition described in the aspect. The dye added as an essential component to the image forming layer, protective layer and backing layer ispreferableIt refers to the dye detailed in the description of the support of the embodiment, and the dye can be used without any particular limitation as long as it is the same as the dye added in the support.
[0110]
In the case where a plurality of dyes used for the support are used, the same dyes as those used for the support are used for the image forming layer, the protective layer and the backing layer, and the dye mass ratio is the same. Is set.
[0111]
  In addition2In the embodiment, the transmission density of the support containing the dye is Ts3, the transmission density of the image forming layer containing the dye is Ti3, the transmission density of the image forming layer containing the dye is Tp3, and the transmission density of the backing layer containing the dye is When the concentration is Tb3, the relationship among Ts3, Ti3, Tp3, and Tb3 is preferably 0.10 ≦ Ts3 / (Ti3 + Tp3 + Tb3) ≦ 4.00.
[0112]
  First of the present invention2In the above aspect, the aforementioned first1In the same manner as in the embodiment, the relationship of 0.10 ≦ Ts3 / (Ti3 + Tp3 + Tb3) ≦ 4.00 can reduce dye deterioration during film formation of the support.
[0113]
  First2In this aspect, it is essential that Ti3, Tp3, and Tb3 are not 0.00. Usually, the value of Ti3 + Tp3 is preferably 0.020 or more, more preferably 0.200 or less, and practically It is within 0.120. The ratio of Ti3 + Tp3 and Tb3 is preferably in the range of 0.07 ≦ Tb3 / (Ti3 + Tp3) ≦ 7.18, and further 0.10 ≦ Tb3 / (Ti3 + Tp3) ≦ 5.00.
[0114]
On the other hand, when the heating drum and the protective layer are brought into contact with each other at the time of thermal development described later, when the dye ratio in the protective layer forming composition is large, the dye holding power of the layer itself at the time of heating is insufficient, Depending on the type, there are cases where the surface of the protective layer is transferred to the bleed or drum surface. Therefore, it cannot be generally defined by the type of the dye, binder resin and various additives to be added, but the dye contained in the protective layer is usually 0.01 to 2.0% by mass in the layer forming composition, It is preferable to make it into the range of 0.05-1.0 mass%.
[0115]
  As mentioned above, the present invention1Aspect or number2With the relationship shown in the above aspect, when the image on the schacus ten is visually observed from the backing layer surface, an image with little change in the color tone of the unexposed portion can be obtained.
[0116]
  preferableEmbodiment,Of the present inventionFirst1Aspects and number2The support used in the embodiment can be produced using a known method. The polyester film which is a preferable support in the present invention will be described in detail. First, sufficiently dried polyester pellets are supplied to a known melt extruder, and further, dyes essential for the present invention and various kinds added as necessary Add the additive, knead well, pass through the filter selected as necessary, then extruded into a sheet shape on a rotating metal casting drum by a T-type die, cooled and solidified, non-oriented state Get the film. Alternatively, undried pellets are supplied to a vented extruder to obtain a non-oriented film in the same manner. Moreover, the ratio (A / B) of the maximum thickness (A) of the edge portion of the film in the non-oriented state and the thickness (B) of the central portion in the width direction is controlled within a range of 2.0 to 6.0. Is preferred. In this case, meandering, width fluctuation, stretching unevenness, and breaking frequency can be effectively suppressed in the longitudinal stretching step.
[0117]
The sufficiently dried polyester pellets used for forming the support include polyester pellets that do not contain recycled dyes, and blue-colored polyester pellets used in photosensitive materials or photothermographic materials. It is out.
[0118]
The non-oriented polyester film obtained as described above is stretched biaxially and vertically. The term “vertical” as used herein means the film longitudinal direction, and the term “lateral” means the width direction. This longitudinal and transverse biaxial stretching is performed by a sequential biaxial method or a simultaneous biaxial method. In the sequential biaxial method, the roll is stretched in the longitudinal direction using the difference in the peripheral speed of the roll, and although it is not particularly limited, it is stretched in the transverse direction using a stenter. The order of stretching in the machine direction and the transverse direction is not particularly limited. In the simultaneous biaxial method, stretching is performed using a simultaneous biaxial tenter. The stretching temperature in the longitudinal and lateral biaxial stretching is in the range of the glass transition temperature (Tg) to (Tg) + 60 ° C. of the polyester, and the more preferable stretching temperature is in the range of (Tg) + 15 ° C. to (Tg) + 45 ° C. The stretching ratio is such that the total stretching ratio in the film longitudinal direction and the width direction is in the range of 1.5 to 8 times, more preferably in the range of 2.5 to 6 times in both the sequential biaxial system and the simultaneous biaxial system. In addition, the total draw ratio said here is longitudinal direction magnification x width direction magnification.
[0119]
  Also,preferableEmbodiment,Of the present inventionFirst1Aspects and number2The backing layer, the image forming layer, the protective layer, and the intermediate layer, etc., which are installed as necessary, are prepared by dissolving or dispersing the components described above in a solvent, respectively, to prepare a coating solution. .
[0120]
Any solvent may be used as long as the solubility parameter shown in the “Solvent Pocket Book” edited by the Synthetic Organic Chemistry Association is in the range of 6.0 to 15.0, and each layer used in the present invention is formed. Examples of the solvent used in the coating liquid include acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, and methyl isobutyl ketone as ketones. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and hexylene glycol. Examples of ether alcohols include ethylene glycol monomethyl ether and diethylene glycol monoethyl ether. Examples of ethers include ethyl ether, dioxane, isopropyl ether and the like.
[0121]
Examples of the esters include ethyl acetate, butyl acetate, amyl acetate, isopropyl acetate and the like. Examples of hydrocarbons include n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene, xylene and the like. Examples of the chlorides include methyl chloride, methylene chloride, chloroform, dichlorobenzene and the like, but not limited thereto as long as the effects of the present invention are not impaired.
[0122]
These solvents can be used alone or in combination of several kinds. The content of the solvent in the image forming material can be adjusted by changing conditions such as temperature conditions in the drying step after the coating step, but the total amount of the residual solvent contained in the photothermographic material is 5%. ~ 1000mg / m²Is more preferable, and more preferably 10 to 300 mg / m.²It is.
[0123]
When dispersion is required when forming the coating liquid, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a cobol mill, a tron mill, a sand mill, a sand grinder, a Sqgvari attritor, a high-speed impeller disperser, a high-speed stone mill, A conventionally known disperser such as a high speed impact mill, a disper, a high speed mixer, a homogenizer, an ultrasonic disperser, an open kneader, or a continuous kneader can be appropriately selected and used.
[0124]
To apply the coating liquid prepared as described above, an extrusion type extrusion coater, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater Various known coater stations such as a transfer roll coater, a kiss coater, a cast coater, and a spray coater can be appropriately selected and used. Among these coaters, it is preferable to use a roll coater such as an extrusion type extrusion coater or a reverse roll coater in order to eliminate unevenness in the thickness of the layer.
[0125]
In addition, when the protective layer is applied, there is no particular limitation as long as the image forming layer is not damaged, but the solvent used in the protective layer forming coating solution dissolves the image forming layer. If possible, an extrusion-type extrusion coater, gravure roll coater, bar coater or the like can be used in the above-described coater station. Of these, when a coating method such as a gravure roll coater or bar coater is used, the rotation direction of the gravure roll or bar may be forward or reverse with respect to the transport direction. May have a constant speed or a peripheral speed difference.
[0126]
Further, as described above, the coating and drying may be repeated for each layer, but the layers may be applied and dried by a wet-on-wet method. In that case, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater, transfer roll coater, kiss coater, cast coater, spray coater, etc. and extrusion type extrusion coater In such a wet-on-wet multi-layer coating, the upper layer is applied while the lower layer is in a wet state, so that the adhesion between the upper and lower layers is improved. .
[0127]
Next, a suitable image recording method for the above-mentioned photothermographic material will be described in detail.
The image recording method of the present invention is roughly divided into three modes depending on the angle formed by the exposure surface and the laser beam, the wavelength of the laser, and the number of lasers used, and these may be performed alone or in combination of two or more. The modes may be combined, and by using such an image forming method, a clear image without interference fringes can be obtained.
[0128]
As a first aspect of the image recording method of the present invention, an image is formed by scanning exposure using laser light in which the angle formed by the exposure surface of the photothermographic material and the laser light is not substantially perpendicular. It is characterized by that. In this way, by shifting the incident angle from the vertical, even if reflected light at the interlayer interface is generated, the optical path difference reaching the image forming layer becomes large, so that the scattering and attenuation of the laser light in the optical path is reduced. It occurs and interference fringes are less likely to occur. Here, “substantially not perpendicular” means that the angle that is closest to the vertical during laser scanning is preferably 55 ° to 88 °, more preferably 60 ° to 86 °, and still more preferably. It means 65 degrees or more and 84 degrees or less.
[0129]
The second aspect of the image recording method of the present invention is characterized in that an image is formed by scanning exposure using a vertical multi-laser having a non-single exposure wavelength. When scanning with such a vertical multi-laser beam having a width in wavelength, the generation of interference fringes is reduced as compared with a scanning laser beam of a vertical single mode. The term “vertical multi” as used herein means that the exposure wavelength is not single, and the normal exposure wavelength distribution is 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.
[0130]
Furthermore, as a third aspect of the image recording method of the present invention, an image is formed by scanning exposure using two or more lasers.
[0131]
As such an image recording method using a plurality of lasers, it is used in an image writing unit of a laser printer or a digital copying machine which writes an image line by line in one scan in response to a demand for high resolution and high speed. This technique is known, for example, from Japanese Patent Laid-Open No. 60-166916. This is a method in which laser light emitted from a light source unit is deflected and scanned by a polygon mirror and imaged on a photoconductor via an fθ lens or the like. This is in principle the same laser scanning optics as a laser imager. Device.
[0132]
The image formation of laser light on the photoconductor in the image writing means of a laser printer or digital copying machine is for one line from the image formation position of one laser light for the purpose of writing an image by a plurality of lines in one scan. The next laser beam imaging position is at the shifted position. Specifically, the two light beams are close to each other in the sub-scanning direction on the image plane with an interval of the order of several tens of μm, and the print density is 400 dpi (in the present invention, 1 inch per inch, that is, 1 per 2.54 cm). The dot printing density is defined as dpi (dot per inch), and the sub-scanning direction pitch of the two beams is 63.5 μm, and 600 dpi is 42.3 μm. Unlike the method of shifting the resolution in the sub-scanning direction as described above, the present invention is characterized in that two or more lasers are converged on the exposure surface by changing the incident angle at the same place to form an image. In this case, when the exposure energy on the exposure surface when writing with one ordinary laser (wavelength λ [nm]) is E, N lasers used for exposure have the same wavelength (wavelength λ [nm] ]), The same exposure energy (En) is preferably in the range of 0.9 × E ≦ En × N ≦ 1.1 × E. By doing so, energy is secured on the exposure surface, but the reflection of each laser beam to the image forming layer is reduced because the exposure energy of the laser is low, and thus the generation of interference fringes is suppressed.
[0133]
In the above description, a plurality of lasers having the same wavelength as λ are used. However, lasers having different wavelengths may be used. In this case, it is preferable that (λ−30) <λ1, λ2,...
[0134]
Furthermore, in the image recording methods of the first, second, and third modes described above, solid-state lasers such as ruby lasers, YAG lasers, and glass lasers that are generally well-known as lasers used for scanning exposure; He— Ne laser, Ar ion laser, Kr ion laser, CO₂Laser, CO laser, He-Cd laser, N₂Gas laser such as laser and excimer laser; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP₂Lasers, semiconductor lasers such as GaSb lasers; chemical lasers, dye lasers, etc. can be appropriately selected and used according to the application. Among these, semiconductor lasers having a wavelength of 700 to 1200 nm are used due to maintenance and light source size problems. It is preferable to use it.
[0135]
In a laser used in a laser imager or a laser image setter, the beam spot diameter on the material exposure surface when scanning a photothermographic material is generally 5 to 75 μm as a short axis diameter and as a long axis diameter. The laser beam scanning speed can be set to an optimum value for each photothermographic material depending on the sensitivity and laser power at the laser oscillation wavelength inherent to the photothermographic material.
[0136]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these. In addition,% in a sentence represents the mass% unless there is particular notice.
[0137]
  referenceExample
  <Preparation of photothermographic material>
  A backing layer forming coating solution was prepared by the method described below.
[0138]
(Preparation of backing layer forming coating solution)
While stirring to 83 g of methyl ethyl ketone, 8.42 g of cellulose acetate butyrate (manufactured by Eastman Chemical Co., CAB381-20) and 0.45 g of polyester resin (manufactured by Toyobo Co., Ltd., Byron 280) were added and dissolved. 1.03 g of infrared dye 1 was added to the dissolved liquid.
[0139]
Separately, 4.34 g of methanol and 0.64 g of F-based surfactant (Asahi Glass Co., Ltd., Surflon S-381 (active ingredient 70%)) and F-based surfactant (Dainippon Ink Industries, Megafag) F120K) 0.23 g was dissolved, the F-based surfactant solution was added to the solution containing the infrared dye 1, and the mixture was sufficiently stirred until the infrared dye 1 was completely dissolved. Finally, 7.5 g of silica dispersed by a dissolver type homogenizer at a concentration of 1% in methyl ethyl ketone (Pyrroid 64 × 6000, manufactured by WR Grace), and a blue coloring dye dissolved in methyl ethyl ketone at a concentration of 0.70% ( CI Solvent Blue 97, λmax = 630 nm: xylene) was sequentially added and stirred to prepare a coating solution for forming a backing layer.
[0140]
Separately, a new polyethylene terephthalate pellet was melted, and C.I. I. Solvent Blue 97 was added and melted and kneaded for 20 minutes. Then, permeation density Ts1 as shown in Table 1 by a known film forming method [manufactured by Konica Corporation, PDA-65: 3 digits after the decimal point, visual density Was measured, and a biaxially stretched polyethylene terephthalate film having a thickness of 175 μm was formed to prepare 10 types of polyethylene terephthalate film supports.
[0141]
One side of these supports is subjected to corona discharge treatment (8 W / m²Min)), the above-mentioned coating solution for forming the backing layer is applied to the corona discharge treated surface with a dry film thickness of 3.5 g / m.²After coating with an extrusion coater so as to form a backing layer containing a blue colored dye having a transmission density shown in Table 1, 10 types of polyethylene terephthalate film supports each having a backing layer were obtained. . The amount of the dye is adjusted so that the transmission density of the finished photothermographic material is within the range of 0.199 ± 0.02, and the transmission density Tb1 of the backing layer containing the blue coloring dye is The transmission density of the support was subtracted from the transmission density of the backing layer and the backing layer.
[0142]
Moreover, the image forming layer forming coating solution and the protective layer forming coating solution were separately prepared by the method shown below.
[0143]
(Preparation of image forming layer forming coating solution)
After dissolving 7.5 g of ossein gelatin having an average molecular weight of 100,000 and 10 mg of potassium bromide in 900 ml of water, adjusting the temperature to 35 ° C. and pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate (98/2) The molar ratio of potassium bromide and potassium iodide is equimolar to silver nitrate and iridium chloride is 1 × 10 5 per mole of silver.^-FourWhile maintaining a pAg of 7.7, 370 ml of a molar aqueous solution was added over 10 minutes by the controlled double jet method. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added and the pH was adjusted to 5 with NaOH to obtain an average particle size of 0.06 μm, a particle size variation coefficient of 12%, Cubic silver iodobromide grains having a (100) face ratio of 87% were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant and desalted, and then 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5 to obtain photosensitive silver halide emulsion 1.
[0144]
Separately, 111.4 g of behenic acid, 83.8 g of arachidic acid, and 54.9 g of stearic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 M aqueous sodium hydroxide solution was added while stirring at high speed, and 6.9 ml of concentrated nitric acid was added, followed by cooling to 55 ° C. to obtain a sodium fatty acid solution.
[0145]
While maintaining the temperature of the prepared fatty acid sodium solution at 55 ° C., photosensitive silver halide emulsion 1 (containing 0.038 mol of silver) and 450 ml of pure water were added and stirred for 5 minutes. Next, 760.6 ml of 1M silver nitrate solution was added over 2 minutes, stirred for another 20 minutes, and water-soluble salts were removed by filtration. Thereafter, washing with deionized water and filtration are repeated until the electric conductivity of the filtrate reaches 2 μS / cm, centrifugal dehydration is performed, and then hot air drying is performed at 37 ° C. until there is no mass loss. Got.
[0146]
Subsequently, 14.57 g of polyvinyl butyral resin (Sekisui Chemical Co., Ltd., ESREC BL-5Z) was dissolved in 1457 g of methyl ethyl ketone, and while stirring with a dissolver type homogenizer, 500 g of the prepared powdered organic silver salt A was gradually added. Added and mixed well. Thereafter, the dispersion was carried out at a peripheral speed of 13 m and a residence time in the mill of 0.5 minutes with a media dispersing machine (Gettzmann) filled with 80% zirconia beads having a particle diameter of 1 mm (manufactured by Toray Industries, Inc.). A dispersion was prepared.
[0147]
Further, 50 g of the photosensitive emulsion dispersion and 10.0 g of methyl ethyl ketone were mixed and kept at 18 ° C. while stirring, 0.320 g of a methanol solution (11.2%) of the antifoggant 1 was added and stirred for 1 hour. Further, 0.212 g of a methanol solution of calcium bromide (11.2%) was added and stirred for 20 minutes, and then 10.0 g of methanol was separately added to 10.0 g of methanol and 1.00 g of dibenzo-18-crown-6. 0.343 g of a solution in which potassium acetate was dissolved was added and stirred for 10 minutes. Next, 4.395 g of the following dye solution 1 was added and stirred for 50 minutes, then 0.0380 g of a thuronium compound (Exemplary Compound 2-7) was added and stirred for 10 minutes, and then the temperature was lowered to 13 ° C. The mixture was further stirred for 60 minutes.
[0148]
(Dye solution 1)
Infrared sensitizing dye 1 0.0086 g
Benzoic acid derivative 1 2.476 g
Methyl ethyl ketone 25.00g
While keeping the solution containing the dye solution at 13 ° C., 13.29 g of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., ESREC BL-5Z) and 0.304 g of tetrachlorophthalic acid were sequentially added. The mixture was dissolved with stirring.
[0149]
In this solution, 2.261 g, 13.543 g, 3.491 g, and 4.597 g of the following additive solutions separately dissolved in methyl ethyl ketone were respectively stirred while being sequentially stirred to form an image forming layer. A forming coating solution was prepared.
[0150]

[0151]
[Chemical formula 5]

[0152]
(Preparation of protective layer forming coating solution)
While stirring to 86.5 g of methyl ethyl ketone, 10.05 g of cellulose acetate butyrate (manufactured by Eastman Chemical Co., CAB171-15), 0.025 g of benzotriazole, fluorine-based activator (manufactured by Asahi Glass Co., Ltd., Surflon KH40) 10 g was added and dissolved.
[0153]
Separately, 55.0 g of a solution of cellulose acetate butyrate (CAB171-15, manufactured by Eastman Chemical Co., Ltd.) having a solid content of 15% was dissolved in methyl ethyl ketone, and silica (Fuji Silysia Chemical Co., Ltd., Silicia 320) was added. 0 g was added and dispersed with a media disperser filled with zirconia beads to prepare a silica dispersion. Next, while stirring the resin solution in which the above-mentioned benzotriazole was dissolved, 3.0 g of silica dispersion was added, and then ultrasonically dispersed to prepare a protective layer forming coating solution.
[0154]
Next, a corona discharge treatment (8 W / m) was performed on the opposite surface of the biaxially stretched polyethylene terephthalate film having a thickness of 175 μm on which the backing layer was formed.²・ After this, the image forming layer forming coating solution and the protective layer forming coating solution prepared by the above method are extruded onto the corona discharge treated surface, followed by multilayer coating using a coater, and warm air at 70 ° C. Then, photothermographic materials 1 to 10 were prepared. The film thickness after drying is 21.0 ± 1.5 g / m for the image forming layer.²The protective layer is 2.35 ± 0.15 g / m²It adjusted so that it might become.
[0155]
<Image recording method and image evaluation>
Using the above-mentioned photothermographic materials 1 to 10 stored at room temperature for 120 hours under light shielding, a semiconductor laser having a wavelength of 800 nm to 820 nm converted into a longitudinal multimode from the protective layer surface side of each material is formed. Using an exposure machine as an exposure source, changing the exposure amount and performing exposure by laser scanning, using an automatic developing machine having a heat drum, so that the protective layer of the photothermographic material and the drum surface are in contact with each other, An image was formed by heat development at 126 ° C. for 13 seconds.
[0156]
Each sample of the obtained photothermographic material subjected to the exposure / heat development treatment was evaluated for image color tone, and the color tone of the unexposed portion and the color tone of the image portion based on the following criteria by sensory evaluation of the image. The obtained results are shown in Table 1.
[0157]
(Image color tone)
The transmission density was measured with a densitometer (manufactured by X-Rite, color transmission densitometer 310T), and the density [V1] giving a density that is +1.0 higher than the unexposed portion at the Visual density and the Blue density [B1] at that time The ratio B1 / V1 was evaluated. In addition, the Visual density | concentration used as an unexposed part +1.0 measures at least 3 or more points between density | concentrations where a density | concentration becomes + unexposed part + 0.7- + 1.2, and calculates | requires the corresponding Blue density | concentration with Visual line The calculation was performed from the regression line of the blue density corresponding to the density and the point at which the visual density becomes the unexposed area + 1.0.
[0158]
(sensory evaluation)
Luminance 10,000 candela / m²The image was visually observed from the surface of the protective layer and the color tone of the unexposed area and the color tone of the image area were evaluated according to the following criteria. If it was not enough, the answer was “There is redness” or “Yellowness”.
[0159]
Unexposed portion color tone: 100 people developing medical image forming materials or systems were visually inspected to determine whether the color tone was sufficient.
[0160]
4 ... 95% or more respondents are enough
3 ... 90% or more and less than 95% responded that enough
2 ... 80% or more and less than 90% are enough
1 ... Less than 80% of respondents
Image part color tone: 100 people developing a medical image forming material or system visually observe a wedge pattern having a transmission density of 0.3 to 3.0 to determine whether or not it is sufficient as a color tone of a black image. received.
[0161]
4 ... 95% or more respondents are enough
3 ... 90% or more and less than 95% responded that enough
2 ... 80% or more and less than 90% are enough
1 ... Less than 80% of respondents
[0162]
[Table 1]

[0163]
  Example1
  <Preparation of photothermographic material>
  A 175 μm thick polyethylene terephthalate film support with a backing layer was prepared in the same manner as in Example 1. In addition, Table 2 shows the transmission density of the produced support and backing layer. The transmission density of the backing layer isReference examples andSimilarly, the amount of blue coloring dye added was adjusted. Table 2 shows the transmission density of the support and the produced backing layer.
[0164]
  Also,Reference examples andIn the same manner, an image-forming layer-forming coating solution containing up to the dye solution 1 was prepared, and this solution was kept at 13 ° C., and a polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., ESREC BL-5Z) 13 .29 g and tetrachlorophthalic acid 0.304 g were sequentially added and sufficiently dissolved by stirring.
[0165]
  To this solution, a blue colored dye (CI Solvent Blue 97) separately dissolved in methyl ethyl ketone at a concentration of 0.70% was added and then dissolved in methyl ethyl ketone.Reference exampleThe additive solutions 1, 2, 3, and 4 were stirred while sequentially stirring 2.261 g, 13.543 g, 3.491 g, and 4.597 g, respectively, to prepare an image forming layer forming coating solution.
[0166]
  Next, the surface opposite to the backing layer of the polyethylene terephthalate film support with the backing layer was subjected to corona discharge treatment (8 W / m²And the image forming layer forming coating solution prepared by the above-described method on the corona discharge-treated surfaceReference exampleThe protective layer-forming coating solution was extruded and coated with a coater, and then dried with hot air at 70 ° C. to produce photothermographic materials 11 to 22 (the amount of the blue coloring dye in the image-forming layer-forming coating solution) The transmission density of the image forming layer was adjusted). The film thickness after drying is 21.0 ± 1.5 g / m for the image forming layer.²The protective layer is 2.35 ± 0.15 g / m²It prepared so that it might become. The transmission density Ti2 of the image forming layer of each photothermographic material is shown in Table 2 together with the transmission density of the support and the backing layer.
[0167]
  The transmission density Ti2 of the image forming layer containing the blue coloring dye is the transmission density when only the protective layer is applied and dried on an untreated polyethylene terephthalate film, and the above-mentioned image forming layer forming coating liquid.Reference exampleThe protective layer-forming coating solution was obtained from an extrusion coater and subtracted from the transmission density when the above-mentioned multilayer coating on a polyethylene terephthalate film coated with only the protective layer was applied and dried.
[0168]
  Next, each sample of the above-mentioned photothermographic material is prepared.Reference examples andAbout the image tone of the sample that was imaged in the same way and obtained and heat-developed.Reference examples andThe sensory evaluation by visual observation of the unexposed portion color tone and the image portion color tone was evaluated according to the following criteria based on the same criteria. The obtained results are shown in Table 2.
[0169]
(sensory evaluation)
Luminance 10,000 candela / m²The image was visually observed from the surface of the protective layer and the backing layer, and the color tone of the unexposed portion and the color tone of the image portion were evaluated according to the following criteria. If it was not enough, the answer was “There is redness” or “Yellowness”.
[0170]
Unexposed portion color tone: 100 people developing medical image forming materials or systems were visually inspected to determine whether the color tone was sufficient.
[0171]
4 ... 95% or more respondents are enough
3 ... 90% or more and less than 95% responded that enough
2 ... 80% or more and less than 90% are enough
1 ... Less than 80% of respondents
Image part color tone: 100 people developing a medical image forming material or system visually observe a wedge pattern having a transmission density of 0.3 to 3.0 to determine whether or not it is sufficient as a color tone of a black image. received.
[0172]
4 ... 95% or more respondents are enough
3 ... 90% or more and less than 95% responded that enough
2 ... 80% or more and less than 90% are enough
1 ... Less than 80% of respondents
[0173]
[Table 2]

[0174]
  Example2
  <Preparation of photothermographic material>
  175 μm thick polyethylene terephthalate film support with backing layerReference examples andThe same method was used. In addition, Table 3 shows the transmission density of the produced support and backing layer.
[0175]
  Examples1In the same manner as above, prepare an image forming layer forming coating solution containing a blue coloring dye, separately,Reference exampleA blue coloring dye (CI Solvent Blue 97) dissolved separately in methyl ethyl ketone at a concentration of 0.70% was added to the protective layer-forming coating solution prepared by ultrasonic dispersion, and after sufficient stirring, again A protective layer forming coating solution was prepared by ultrasonic dispersion.
[0176]
  Next, a corona discharge treatment (8 W / m) was performed on the surface opposite to the backing layer of the 175 μm-thick biaxially stretched polyethylene terephthalate film with the backing layer.²On the surface treated with corona discharge.1The coating solution for forming an image forming layer prepared by the same method as above and the coating solution for forming a protective layer prepared by adding a blue coloring dye by the above-mentioned method are extruded by multilayer coating using a coater, and then heated with 70 ° C hot air A photothermographic material was prepared by drying. The film thickness after drying is 21.0 ± 1.5 g / m for the image forming layer.²The protective layer is 2.35 ± 0.15 g / m²It adjusted so that it might become. The transmission density of the image forming layer and the protective layer was adjusted by changing the amount of blue coloring dye added to each coating solution. Table 3 shows the transmission densities of the protective layer and the image forming layer of the photothermographic materials 23 to 34 thus prepared, together with the transmission densities of the support and the backing layer.
[0177]
The transmission density Tp3 of the protective layer containing the blue coloring dye was measured by measuring the transmission density when only the protective layer was applied and dried on the untreated polyethylene terephthalate film, and the transmission density Ti3 of the image forming layer was From the transmission density of the photothermographic material prepared in this example, the transmission density of only the protective layer described above and the transmission density of the biaxially stretched polyethylene terephthalate film laminated on the backing layer were obtained.
[0178]
  Next, each sample of the above-mentioned photothermographic material is prepared.Reference examples andForm the image in the same way, and adjust the color tone of the resulting exposed and heat-developed image.Reference examples andExample of sensory evaluation of visually unexposed color tone and image color tone based on the same criteria1Was evaluated according to the same criteria. The obtained results are shown in Table 3.
[0179]
[Table 3]

[0180]
  Example3
  Reference exampleWhen forming the support used in the photothermographic materials 1, 3 to 8 and 10, except that the melt kneading time of the blue colored dye and the novel polyethylene terephthalate pellet was tripled,Reference examples andSimilarly, a photothermographic material was prepared, and photothermographic materials 35 to 42 were obtained.
[0181]
  Each sample of this photothermographic materialReference examples andThe color tone, unexposed color tone and image color tone of the exposed and heat-developed image obtained by the same method are visually evaluated by sensory evaluation.Reference examples andEvaluation was based on the same criteria. The results obtained are shown in Table 4.
[0182]
[Table 4]

[0183]
  Example4
  Polyethylene terephthalate pellets used when forming the support were mixed with new polyethylene terephthalate pellets in the proportions shown in Table 5 and once made into a film, a 0.160 polyethylene terephthalate film was re-pelletized and used. except,Reference examples andSimilarly, photothermographic materials 43 to 51 were produced.
[0184]
  Each sample of this photothermographic materialReference examples andImage formation by the same method, and the color tone, unexposed color tone and image color tone of the obtained exposed and heat-developed image were visually evaluated by sensory evaluation.Reference examples andEvaluation was based on the same criteria. The results obtained are shown in Table 5.
[0185]
[Table 5]

[0186]
  Example5
  Reference examples andExample 14Except that the photothermographic material shown in Table 6 was subjected to image exposure by the following image recording method from the photothermographic material prepared in 1.Reference examples andUsing the same automatic developing machine, heat development was performed at 122 ° C. for 16 seconds to form an image. For each of the obtained samples, the interference fringes of the image were evaluated by sensory evaluation and density measurement (ΔD) according to the following criteria. The results obtained are shown in Table 6. In addition, exposure amountIn reference exampleThe exposure energy on the surface of the protective layer was adjusted to be the same.
[0187]
<Image recording method 1>
From the protective layer surface side of the photothermographic material, exposure by laser scanning was given by an exposure machine using a semiconductor laser having a wavelength of 820 nm as an exposure source. At this time, the angle of the exposure surface of the photothermographic material and the exposure laser beam was set to 90 degrees, and image exposure was performed.
[0188]
<Image recording method 2>
From the protective layer surface side of the photothermographic material, exposure by laser scanning was given by an exposure machine using a semiconductor laser having a wavelength of 820 nm as an exposure source. At this time, the image exposure was performed with the angle of the exposure surface of the photothermographic material and the exposure laser light set to 70 degrees.
[0189]
<Image recording method 3>
From the surface of the protective layer surface of the photothermographic material, exposure by laser scanning was given by an exposure machine using a semiconductor laser having a longitudinal multimode wavelength of 800 nm to 820 nm by high frequency superposition as an exposure source. At this time, the image exposure was performed with the angle of the exposure surface of the photothermographic material and the exposure laser beam being 90 degrees.
[0190]
<Image recording method 4>
From the side of the protective layer surface of the photothermographic material, two laser beams having a wavelength of 820 nm are used as exposure sources, and two laser beams emitted simultaneously are deflected and scanned by a polygon mirror, and then applied to the photothermographic material via an fθ lens. Exposure by laser scanning was given using an exposure machine that focused light. At this time, image exposure was performed with the angle of the exposure surface of the photothermographic material and the exposure laser beam set to 85 ° for one laser beam and 95 ° for the other. The energy intensity of each laser beam on the exposed surface was the same, and the energy intensity was ½ that of the image recording method 1, respectively.
[0191]
(sensory evaluation)
An image that has been exposed and heat-developed so that the transmission density is 1.80 ± 0.15 has a luminance of 10000 candela / m.²Samples were placed on the Schaukasten, and the degree of occurrence of interference fringes was ranked as shown below, and sensory evaluation was performed.
[0192]
4: No interference fringes are observed.
3: Interference fringes are slightly observed.
[0193]
2: Interference fringes are clearly observed partially.
1: Interference fringes are clearly observed on the entire surface.
[0194]
(Density measurement (ΔD))
If the interference fringe pattern is clear by scanning and measuring the density of the image area using a densitometer that can squeeze the slit opening, it is quantitatively expressed as the difference in transmission density between the bright and dark stripes. Can be evaluated. Therefore, an image that has been exposed and heat-developed so that the transmission density is 1.80 ± 0.15 is measured with a microdensitometer (Konica Microdensitometer PDM-7 type BR). Measurements were made at 5 locations (total number of measurement points: 4000) at an interval of 25 μm and a measurement length of 20 mm, and the sensory evaluation described above was correlated with the concentration difference ΔD. The smaller ΔD, the less interference fringes are generated.
[0195]
ΔD = (maximum concentration at measurement point) − (minimum concentration at measurement point)
[0196]
[Table 6]

[0197]
【The invention's effect】
It was possible to provide a photothermographic material excellent in the color tone of the unexposed part and the image part of the photothermographic material and excellent in recyclability of the support and a suitable image recording method using the photothermographic material. .

Claims (8)

In a photothermographic material in which at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on a support, a backing layer is formed on the surface opposite to the image forming layer. A photothermographic material comprising the same dye having λmax of 600 to 650 nm in the support , the image forming layer and the backing layer. Transmission density measured by visual density of the support containing dye, Ts 2 , transmission density measured by visual density of image-forming layer containing dye, Ti 2, transmission density measured by visual density of backing layer containing dye , Where Tb 2 is 0.10 ≦ Ts 2 / ( Ti 2 + Tb 2 ) ≦ 4 . 2. The photothermographic material according to claim 1, wherein the photothermographic material is 00. In a photothermographic material in which at least an organic silver salt, a photosensitive silver halide, an image forming layer containing a reducing agent, and a protective layer are laminated in this order on a support, a backing layer is formed on the surface opposite to the image forming layer. A photothermographic material comprising the same dye having λmax of 600 to 650 nm in the support, the image forming layer , the protective layer and the backing layer. Transmission density measured by visual density of the support containing dye, Ts 3 , transmission density measured by visual density of the image-forming layer containing dye, Ti 3 , transmission measured by visual density of the protective layer containing dye wherein the Tp3 concentrations, the transmission density measured at the visual density of the backing layer containing a dye is taken as Tb 3, 0.10 ≦ Ts 3 / (Ti 3 + Tp3 + Tb 3) is ≦ 4.00 The photothermographic material according to claim 3.   Scanning exposure is performed on the photothermographic material according to any one of claims 1 to 4 using a laser in which an angle formed by an exposure surface and a laser beam is not substantially perpendicular. Image recording method. An image recording method, wherein the photothermographic material according to any one of claims 1 to 4 is subjected to scanning exposure using a vertical multi-laser having a non-single exposure wavelength. 5. An image recording method, wherein the photothermographic material according to any one of claims 1 to 4 is subjected to scanning exposure using two or more lasers. The image recording method according to claim 5, wherein the wavelength of the laser used for scanning exposure is in the range of 700 to 1200 nm .