JP4221197B2 - Photothermographic material and image forming method - Google Patents

Description

【００５４】
（一般式（Ｒ）において、Ｒ¹¹およびＲ¹¹'は各々独立に炭素数１〜２０のアルキル基を表す。Ｒ¹²およびＲ¹²'は各々独立に水素原子またはベンゼン環に置換可能な置換基を表す。Ｌは−Ｓ−基または−ＣＨＲ¹³−基を表す。Ｒ¹³は水素原子または炭素数１〜２０のアルキル基を表す。Ｘ¹およびＸ¹'は各々独立に水素原子またはベンゼン環に置換可能な基を表す。）
【００５５】
一般式（Ｒ）について詳細に説明する。
Ｒ¹¹およびＲ¹¹'は各々独立に置換または無置換の炭素数１〜２０のアルキル基であり、アルキル基の置換基は特に限定されることはないが、好ましくは、アリール基、ヒドロキシ基、アルコキシ基、アリールオキシ基、アルキルチオ基、アリールチオ基、アシルアミノ基、スルホンアミド基、スルホニル基、ホスホリル基、アシル基、カルバモイル基、エステル基、ハロゲン原子等があげられる。
【００５６】
Ｒ¹²およびＲ¹²'は各々独立に水素原子またはベンゼン環に置換可能な置換基であり、Ｘ¹およびＸ¹'も各々独立に水素原子またはベンゼン環に置換可能な基を表す。それぞれベンゼン環に置換可能な基としては、好ましくはアルキル基、アリール基、ハロゲン原子、アルコキシ基、アシルアミノ基があげられる。
【００５７】
Ｌは−Ｓ−基または−ＣＨＲ¹³−基を表す。Ｒ¹³は水素原子または炭素数１〜２０のアルキル基を表し、アルキル基は置換基を有していてもよい。
Ｒ¹³の無置換のアルキル基の具体例はメチル基、エチル基、プロピル基、ブチル基、ヘプチル基、ウンデシル基、イソプロピル基、１−エチルペンチル基、２，４，４−トリメチルペンチル基などがあげられる。
アルキル基の置換基の例はＲ¹¹の置換基と同様で、ハロゲン原子、アルコキシ基、アルキルチオ基、アリールオキシ基、アリールチオ基、アシルアミノ基、スルホンアミド基、スルホニル基、ホスホリル基、オキシカルボニル基、カルバモイル基、スルファモイル基などがあげられる。
【００５８】
Ｒ¹¹およびＲ¹¹'として好ましくは炭素数３〜１５の２級または３級のアルキル基であり、具体的にはイソプロピル基、イソブチル基、ｔ−ブチル基、ｔ−アミル基、ｔ−オクチル基、シクロヘキシル基、シクロペンチル基、１−メチルシクロヘキシル基、１−メチルシクロプロピル基などがあげられる。
Ｒ¹¹およびＲ¹¹'としてより好ましくは炭素数４〜１２の３級アルキル基で、その中でもｔ−ブチル基、ｔ−アミル基、１−メチルシクロヘキシル基が更に好ましく、ｔ−ブチル基が最も好ましい。
【００５９】
Ｒ¹²およびＲ¹²'として好ましくは炭素数１〜２０のアルキル基であり、具体的にはメチル基、エチル基、プロピル基、ブチル基、イソプロピル基、ｔ−ブチル基、ｔ−アミル基、シクロヘキシル基、１−メチルシクロヘキシル基、ベンジル基、メトキシメチル基、メトキシエチル基などがあげられる。より好ましくはメチル基、エチル基、プロピル基、イソプロピル基、ｔ−ブチル基である。
Ｘ¹およびＸ¹'は、好ましくは水素原子、ハロゲン原子、アルキル基で、より好ましくは水素原子である。
【００６０】
Ｌは好ましくは−ＣＨＲ¹³−基である。
Ｒ¹³として好ましくは水素原子または炭素数１〜１５のアルキル基であり、アルキル基としてはメチル基、エチル基、プロピル基、イソプロピル基、２，４，４−トリメチルペンチル基が好ましい。Ｒ¹³として特に好ましいのは水素原子、メチル基、プロピル基またはイソプロピル基である。
【００６１】
Ｒ¹³が水素原子である場合、Ｒ¹²およびＲ¹²'は好ましくは炭素数２〜５のアルキル基であり、エチル基、プロピル基がより好ましく、エチル基が最も好ましい。
Ｒ¹³が炭素数１〜８の１級または２級のアルキル基である場合、Ｒ¹²およびＲ¹²'はメチル基が好ましい。Ｒ¹³の炭素数１〜８の１級または２級のアルキル基としてはメチル基、エチル基、プロピル基、イソプロピル基がより好ましく、メチル基、エチル基、プロピル基が更に好ましい。
Ｒ¹¹、Ｒ¹¹’、Ｒ¹²およびＲ¹²’がいずれもメチル基である場合には、Ｒ¹³は２級のアルキル基であることが好ましい。この場合Ｒ¹³の２級アルキル基としてはイソプロピル基、イソブチル基、１−エチルペンチル基が好ましく、イソプロピル基がより好ましい。
【００６２】
以下に本発明の一般式（Ｒ）で表される化合物をはじめとする本発明の還元剤の具体例を示すが、本発明はこれらに限定されるものではない。
【００６３】
【化２】

【００６４】
【化３】

【００６５】
【化４】

【００６６】
特に（Ｉ−１）〜（Ｉ−２０）に示すような化合物であることが好ましい。
【００６７】
本発明において還元剤の添加量は０．０１〜５．０ｇ／ｍ²であることが好ましく、０．１〜３．０ｇ／ｍ²であることがより好ましく、画像形成層を有する面の銀１モルに対しては５〜５０モル％含まれることが好ましく、１０〜４０モル％で含まれることがさらに好ましい。還元剤は画像形成層に含有させることが好ましい。
【００６８】
還元剤は溶液形態、乳化分散形態、固体微粒子分散物形態など、いかなる方法で塗布液に含有せしめ、感光材料に含有させてもよい。
よく知られている乳化分散法としては、ジブチルフタレート、トリクレジルフォスフェート、グリセリルトリアセテートあるいはジエチルフタレートなどのオイル、酢酸エチルやシクロヘキサノンなどの補助溶媒を用いて溶解し、機械的に乳化分散物を作製する方法が挙げられる。
【００６９】
また、固体微粒子分散法としては、還元剤の粉末を水等の適当な溶媒中にボールミル、コロイドミル、振動ボールミル、サンドミル、ジェットミル、ローラーミルあるいは超音波によって分散し、固体分散物を作成する方法が挙げられる。尚、その際に保護コロイド（例えば、ポリビニルアルコール）、界面活性剤（例えばトリイソプロピルナフタレンスルホン酸ナトリウム（３つのイソプロピル基の置換位置が異なるものの混合物）などのアニオン性界面活性剤）を用いてもよい。水分散物には防腐剤（例えばベンゾイソチアゾリノンナトリウム塩）を含有させることができる。
【００７０】
（現像促進剤の説明）
本発明の熱現像感光材料では、現像促進剤として以下の一般式（Ａ）で表されるフェノール誘導体が好ましく用いられる。
【００７１】
【化５】

【００７２】
式（Ａ）において、Ｒ¹、Ｒ²、Ｒ³、Ｘ¹¹およびＸ¹²はそれぞれ独立に水素原子、ハロゲン原子、または炭素原子、酸素原子、窒素原子、硫黄原子もしくはリン原子でベンゼン環に結合する置換基を表す。但し、Ｘ¹¹、Ｘ¹²の少なくとも一方は、−ＮＲ⁴Ｒ⁵で表される基である。
Ｒ⁴、Ｒ⁵はそれぞれ独立に水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、ヘテロ環基、あるいは−Ｃ（＝Ｏ）−Ｒ、−Ｃ（＝Ｏ）−Ｃ（＝Ｏ）−Ｒ、−ＳＯ₂−Ｒ、−ＳＯ−Ｒ、−Ｐ（＝Ｏ）（Ｒ）₂または−Ｃ（＝ＮＲ′）−Ｒで表される基である。
Ｒ、Ｒ′はそれぞれ独立に水素原子、アルキル基、アリール基、ヘテロ環基、アミノ基、アルコキシ基、アリールオキシ基から選ばれる基である。これらの置換基はそれぞれ隣接する基同士が結合して環を形成してもよい。
【００７３】
（水素結合性化合物の説明）
本発明における還元剤が芳香族性の水酸基（−ＯＨ）を有する場合、特に前述のビスフェノール類の場合には、これらの基と水素結合を形成することが可能な基を有する非還元性の化合物を併用することが好ましい。
水酸基またはアミノ基と水素結合を形成する基としては、ホスホリル基、スルホキシド基、スルホニル基、カルボニル基、アミド基、エステル基、ウレタン基、ウレイド基、３級アミノ基、含窒素芳香族基などが挙げられる。
【００７４】
その中でも好ましいのはホスホリル基、スルホキシド基、アミド基（但し、＞Ｎ−Ｈ基を持たず、＞Ｎ−Ｒa（ＲaはＨ以外の置換基）のようにブロックされている。）、ウレタン基（但し、＞Ｎ−Ｈ基を持たず、＞Ｎ−Ｒa（ＲaはＨ以外の置換基）のようにブロックされている。）、ウレイド基（但し、＞Ｎ−Ｈ基を持たず、＞Ｎ−Ｒa（ＲaはＨ以外の置換基）のようにブロックされている。）を有する化合物である。
【００７５】
本発明で、特に好ましい水素結合性の化合物は下記一般式（Ｄ）で表される化合物である。
【００７６】
【化６】

【００７７】
一般式（Ｄ）において、Ｒ²¹ないしＲ²³は各々独立にアルキル基、アリール基、アルコキシ基、アリールオキシ基、アミノ基またはヘテロ環基を表し、これらの基は無置換であっても置換基を有していてもよい。
【００７８】
Ｒ²¹ないしＲ²³が置換基を有する場合の置換基としてはハロゲン原子、アルキル基、アリール基、アルコキシ基、アミノ基、アシル基、アシルアミノ基、アルキルチオ基、アリールチオ基、スルホンアミド基、アシルオキシ基、オキシカルボニル基、カルバモイル基、スルファモイル基、スルホニル基、ホスホリル基などがあげられ、置換基として好ましいのはアルキル基またはアリール基でたとえばメチル基、エチル基、イソプロピル基、ｔ−ブチル基、ｔ−オクチル基、フェニル基、４−アルコキシフェニル基、４−アシルオキシフェニル基などがあげられる。
【００７９】
Ｒ²¹ないしＲ²³のアルキル基としては具体的にはメチル基、エチル基、ブチル基、オクチル基、ドデシル基、イソプロピル基、ｔ−ブチル基、ｔ−アミル基、ｔ−オクチル基、シクロヘキシル基、１−メチルシクロヘキシル基、ベンジル基、フェネチル基、２−フェノキシプロピル基などがあげられる。
アリール基としてはフェニル基、クレジル基、キシリル基、ナフチル基、４−ｔ−ブチルフェニル基、４−ｔ−オクチルフェニル基、４−アニシジル基、３，５−ジクロロフェニル基などが挙げられる。
【００８０】
アルコキシ基としてはメトキシ基、エトキシ基、ブトキシ基、オクチルオキシ基、２−エチルヘキシルオキシ基、３，５，５−トリメチルヘキシルオキシ基、ドデシルオキシ基、シクロヘキシルオキシ基、４−メチルシクロヘキシルオキシ基、ベンジルオキシ基等が挙げられる。
アリールオキシ基としてはフェノキシ基、クレジルオキシ基、イソプロピルフェノキシ基、４−ｔ−ブチルフェノキシ基、ナフトキシ基、ビフェニルオキシ基等が挙げられる。
アミノ基としてはジメチルアミノ基、ジエチルアミノ基、ジブチルアミノ基、ジオクチルアミノ基、Ｎ−メチル−Ｎ−ヘキシルアミノ基、ジシクロヘキシルアミノ基、ジフェニルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基等が挙げられる。
【００８１】
Ｒ²¹ないしＲ²³としてはアルキル基、アリール基、アルコキシ基、アリールオキシ基が好ましい。本発明の効果の点ではＲ²¹ないしＲ²³のうち少なくとも一つ以上がアルキル基またはアリール基であることが好ましく、二つ以上がアルキル基またはアリール基であることがより好ましい。また、安価に入手する事ができるという点ではＲ²¹ないしＲ²³が同一の基である場合が好ましい。
【００８２】
以下に本発明における一般式（Ｄ）の化合物をはじめとする水素結合性化合物の具体例を示すが、本発明はこれらに限定されるものではない。
【００８３】
【化７】

【００８４】
【化８】

【００８５】
水素結合性化合物の具体例は上述の他に特願2000-192191号、同2000-194811号に記載のものがあげられる。
本発明で使用することができる一般式（Ｄ）の化合物は、還元剤と同様に溶液形態、乳化分散形態、固体分散微粒子分散物形態で塗布液に含有せしめ、感光材料中で使用することができる。本発明の化合物は、溶液状態でフェノール性水酸基、アミノ基を有する化合物と水素結合性の錯体を形成しており、還元剤と一般式（Ｄ）の化合物との組み合わせによっては錯体として結晶状態で単離することができる。
【００８６】
このようにして単離した結晶粉体を固体分散微粒子分散物として使用することは安定した性能を得る上で特に好ましい。また、還元剤と一般式（Ｄ）の化合物を粉体で混合し、適当な分散剤を使って、サンドグラインダーミル等で分散時に錯形成させる方法も好ましく用いることができる。
【００８７】
本発明で使用することができる一般式（Ｄ）の化合物は還元剤に対して、１〜２００モル％の範囲で使用することが好ましく、より好ましくは１０〜１５０モル％の範囲で、さらに好ましくは３０〜１００モル％の範囲である。
【００８８】
（バインダーの説明）
本発明の有機銀塩含有層のバインダーはいかなるポリマーであってもよく、好適なバインダーは透明又は半透明で、一般に無色であり、天然樹脂やポリマー及びコポリマー、合成樹脂やポリマー及びコポリマー、その他フィルムを形成する媒体、例えば、ゼラチン類、ゴム類、ポリ（ビニルアルコール）類、ヒドロキシエチルセルロース類、セルロースアセテート類、セルロースアセテートブチレート類、ポリ（ビニルピロリドン）類、カゼイン、デンプン、ポリ（アクリル酸）類、ポリ（メチルメタクリル酸）類、ポリ（塩化ビニル）類、ポリ（メタクリル酸）類、スチレン−無水マレイン酸共重合体類、スチレン−アクリロニトリル共重合体類、スチレン−ブタジエン共重合体類、ポリ（ビニルアセタール）類（例えば、ポリ（ビニルホルマール）及びポリ（ビニルブチラール））、ポリ（エステル）類、ポリ（ウレタン）類、フェノキシ樹脂、ポリ（塩化ビニリデン）類、ポリ（エポキシド）類、ポリ（カーボネート）類、ポリ（酢酸ビニル）類、ポリ（オレフィン）類、セルロースエステル類、ポリ（アミド）類がある。バインダーは水又は有機溶媒またはエマルションから被覆形成してもよい。
【００８９】
本発明では、有機銀塩を含有する層に併用できるバインダーのガラス転移温度は０℃以上８０℃以下である（以下、高Ｔｇバインダーということあり）ことが好ましく、１０℃以上７０℃以下であることがより好ましく、１５℃以上６０℃以下であることが更に好ましい。
【００９０】
なお、本明細書においてＴｇは下記の式で計算した。
１／Ｔｇ＝Σ(Ｘi／Ｔｇi)
ここでは、ポリマーはｉ＝１からｎまでのｎ個のモノマー成分が共重合しているとする。Ｘiはi番目のモノマーの重量分率（ΣＸi＝１）、Ｔｇiはi番目のモノマーの単独重合体のガラス転移温度（絶対温度）である。ただしΣはｉ＝１からｎまでの和をとる。
尚、各モノマーの単独重合体ガラス転移温度の値（Ｔｇi）はPolymer Handbook (3rd Edition)(J.Brandrup, E.H.Immergut著(Wiley-Interscience、1989))の値を採用した。
【００９１】
バインダーとなるポリマーは単独種で用いてもよいし、必要に応じて２種以上を併用しても良い。また、ガラス転移温度が２０℃以上のものとガラス転移温度が２０℃未満のものを組み合わせて用いてもよい。Ｔｇの異なるポリマーを２種以上ブレンドして使用する場合には、その重量平均Ｔｇが上記の範囲にはいることが好ましい。
【００９２】
本発明においては、有機銀塩含有層が溶媒の３０質量％以上が水である塗布液を用いて塗布し、乾燥して形成される場合に、さらに有機銀塩含有層のバインダーが水系溶媒（水溶媒）に可溶または分散可能である場合に、特に２５℃６０％ＲＨでの平衡含水率が２質量％以下のポリマーのラテックスからなる場合に性能が向上する。最も好ましい形態は、イオン伝導度が２．５ｍＳ／ｃｍ以下になるように調製されたものであり、このような調製法としてポリマー合成後分離機能膜を用いて精製処理する方法が挙げられる。
【００９３】
ここでいう前記ポリマーが可溶または分散可能である水系溶媒とは、水または水に７０質量％以下の水混和性の有機溶媒を混合したものである。
水混和性の有機溶媒としては、例えば、メチルアルコール、エチルアルコール、プロピルアルコール等のアルコール系、メチルセロソルブ、エチルセロソルブ、ブチルセロソルブ等のセロソルブ系、酢酸エチル、ジメチルホルミアミドなどを挙げることができる。
【００９４】
なお、ポリマーが熱力学的に溶解しておらず、いわゆる分散状態で存在している系の場合にも、ここでは水系溶媒という言葉を使用する。
【００９５】
また「２５℃６０％ＲＨにおける平衡含水率」とは、２５℃６０％ＲＨの雰囲気下で調湿平衡にあるポリマーの重量Ｗ１と２５℃で絶乾状態にあるポリマーの重量Ｗ０を用いて以下のように表すことができる。
２５℃６０％ＲＨにおける平衡含水率＝[(Ｗ１−Ｗ０)／Ｗ０]×１００(質量％)
【００９６】
含水率の定義と測定法については、例えば高分子工学講座１４、高分子材料試験法(高分子学会編、地人書館)を参考にすることができる。
【００９７】
本発明のバインダーポリマーの２５℃６０％ＲＨにおける平衡含水率は２質量％以下であることが好ましいが、より好ましくは０．０１質量％以上１．５質量％以下、さらに好ましくは０．０２質量％以上１質量％以下が望ましい。
【００９８】
本発明においては水系溶媒に分散可能なポリマーが特に好ましい。分散状態の例としては、水不溶な疎水性ポリマーの微粒子が分散しているラテックスやポリマー分子が分子状態またはミセルを形成して分散しているものなどがあるが、いずれも好ましい。分散粒子の平均粒径は１〜５００００ｎｍ、より好ましくは５〜１０００ｎｍ程度の範囲が好ましい。分散粒子の粒径分布に関しては特に制限は無く、広い粒径分布を持つものでも単分散の粒径分布を持つものでもよい。
【００９９】
本発明において水系溶媒に分散可能なポリマーの好ましい態様としては、アクリル系ポリマー、ポリ（エステル）類、ゴム類(例えばＳＢＲ樹脂)、ポリ（ウレタン）類、ポリ（塩化ビニル）類、ポリ（酢酸ビニル）類、ポリ（塩化ビニリデン）類、ポリ（オレフィン）類等の疎水性ポリマーを好ましく用いることができる。
これらポリマーとしては直鎖のポリマーでも枝分かれしたポリマーでもまた架橋されたポリマーでもよいし、単一のモノマーが重合したいわゆるホモポリマーでもよいし、２種類以上のモノマーが重合したコポリマーでもよい。コポリマーの場合はランダムコポリマーでも、ブロックコポリマーでもよい。
これらポリマーの分子量は数平均分子量で５０００〜１００００００、好ましくは１００００〜２０００００がよい。分子量が小さすぎるものは乳剤層の力学強度が不十分であり、大きすぎるものは成膜性が悪く好ましくない。
【０１００】
＜ラテックスの合成方法＞
本発明で好ましく用いることのできる高Ｔｇポリマー微細分散物は乳化重合、分散重合、懸濁重合、など通常の重合反応により得ることができる。しかしながら写真感光材料の塗布の多くが水を媒体とし、該共重合体の様な非水溶性物質は水分散物の形態で扱われるため、塗布液調製の観点で乳化重合または分散重合が好ましく、乳化重合で合成されることが特に好ましい。
該ラテックスを使用する場合は、通常微粒子の粒径は３００ｎｍ以下で用いられる。その中でも粒径が２００ｎｍ以下であることが好ましく、１５０ｎｍ以下であることが特に好ましい。
【０１０１】
乳化重合法は、例えば、水あるいは水と水に混和しうる有機溶媒（例えばメタノール、エタノール、アセトンなど）との混合溶媒を分散媒とし、分散媒に対して５〜４０重量％のモノマー混合物と、モノマーに対して０．０５〜５重量％の重合開始剤、０．１〜２０重量％の乳化剤を用い、３０〜１００℃程度、好ましくは６０〜９０℃で３〜８時間、攪拌下重合させることにより行われる。
分散媒、モノマーの濃度、開始剤量、乳化剤量、反応温度、時間、モノマー添加方法などの条件は使用するモノマーの種類や粒子の目標粒径などを考慮し、適宜設定される。
【０１０２】
乳化重合に好ましく用いられる開始剤としては、過硫酸カリウム、過硫酸ナトリウム、過硫酸アンモニウム等の無機過酸化物、アゾビスシアノ吉草酸のナトリウム塩等のアゾニトリル化合物、２，２′−アゾビス（２−アミジノプロパン）二塩酸塩等のアゾアミジン化合物、２，２′−アゾビス〔２−（５−メチル−２−イミダゾリン−２−イル）プロパン〕塩酸塩等の環状アゾアミジン化合物、２，２′−アゾビス｛２−メチル−Ｎ−〔１，１′−ビス（ヒドロキシメチル）−２−ヒドロキシエチル〕プロピオンアミド｝等のアゾアミド化合物が挙げられる。この中でも過硫酸カリウム、過硫酸ナトリウム、過硫酸アンモニウムが特に好ましい。
【０１０３】
分散剤としてはアニオン性界面活性剤、ノニオン性界面活性剤、カチオン性界面活性剤、両性界面活性剤のいずれも用いることができるが、好ましくはアニオン性界面活性剤である。
【０１０４】
高Ｔｇラテックスは通常の乳化重合法の手法に則り、容易に合成可能である。一般的な乳化重合の方法については以下の成書に詳しい。
「合成樹脂エマルジョン（奥田平、稲垣寛編集、高分子刊行会発行(1978)）」、「合成ラテックスの応用（杉村孝明、片岡靖男、鈴木聡一、笠原啓司編集、高分子刊行会発行(1993)）」、「合成ラテックスの化学（室井宗一著、高分子刊行会発行(1970)）」。
【０１０５】
以下に高Ｔｇラテックスの合成を、具体的合成例を挙げて詳説する。
合成例１
ガラス製オートクレーブ（耐圧硝子工業（株）製TEM-V1000）にスチレン９０ｇ、アクリル酸３ｇ、蒸留水１６０g、界面活性剤（サンデットＢＬ（三洋化成（株）製））２g、を入れて窒素気流下で１時間攪拌した。その後反応容器を密閉してブタジエン７ｇを添加して６０℃まで昇温した。ここに過硫酸カリウム水溶液（５％）を１０ｇ添加して、そのまま１０時間攪拌して反応させた。反応後温度を室温まで下た後、蒸留水６０ｇを加えて３０分撹拌して乳白色液体のラテツクスｇを３２７ｇを得た。
この分散液は不揮発分３０．２質量％を含む平均粒子径７６ｎｍの微細ラテックス液であった。粒子サイズはコールター社粒子測定装置Ｎ４を用いて動的光散乱法により評価した。
【０１０６】
合成例２
冷却管と攪拌装置を取り付けた５００ｍｌ三ツ口フラスコに、界面活性剤としてドデシル硫酸ナトリウム２ｇを蒸留水２５０ｍｌに溶解した溶液を入れ、次いでスチレン８０ｇ、２−エチルヘキシルアクリレート１５ｇとアクリル酸５ｇの混合溶液を加え、窒素気流下で２００ｒｐｍの速度で攪拌した。この反応溶液を７５℃に加熱し、過硫酸カリウム０．２ｇを蒸留水１０mlに溶解した溶液を添加して２時間重合させた。さらに過硫酸カリウム０．２ｇを蒸留水１０mlに溶解した溶液を添加して２時間重合させた。
この反応液を室温まで冷却し、分画分子量１万のセルロース膜を用いて透析し、過剰な界面活性剤や無機塩類を除去した後、減圧濃縮し、濾過にて不溶分を除去して微乳濁白色の分散液３８０ｇを得た。
この分散液は不揮発分２６．３重量％を含む平均粒子径６６ｎｍの微細ラテックス液であった。
【０１０７】
本発明に用いられる他の高Ｔｇラテックスも上記の方法と同等の方法で容易に合成可能である。
【０１０８】
高Ｔｇラテックスの使用量は、感材の１ｍ²あたり１ｇから２０ｇの範囲で使用することができ、さらに好ましくは１ｇから１５ｇの範囲である。本発明の他の高Ｔｇラテックスと２種以上ブレンドして用いても良く、また本発明に含まれない他のラテックス、もしくはポリマーバインダーと併用して用いても良い。
【０１０９】
（好ましい塗布液の溶媒）
本発明において感光材料の有機銀塩含有層塗布液の溶媒（ここでは簡単のため、溶媒と分散媒をあわせて溶媒と表す。）は、水を３０質量％以上含む水系溶媒が好ましい。水以外の成分としてはメチルアルコール、エチルアルコール、イソプロピルアルコール、メチルセロソルブ、エチルセロソルブ、ジメチルホルムアミド、酢酸エチルなど任意の水混和性有機溶媒を用いてよい。塗布液の溶媒の水含有率は５０質量％以上、より好ましくは７０質量％以上が好ましい。
好ましい溶媒組成の例を挙げると、水の他、水／メチルアルコール＝９０／１０、水／メチルアルコール＝７０／３０、水／メチルアルコール／ジメチルホルムアミド＝８０／１５／５、水／メチルアルコール／エチルセロソルブ＝８５／１０／５、水／メチルアルコール／イソプロピルアルコール＝８５／１０／５などがある（数値は質量％）。
【０１１０】
（かぶり防止剤の説明）
本発明に用いることのできるカブリ防止剤、安定剤および安定剤前駆体特開平10-62899号の段落番号００７０、欧州特許公開第0803764A1号の第20頁第57行〜第21頁第７行に記載の特許のもの、特開平9-281637号、同9-329864号記載の化合物が挙げられる。
また本発明においてはカブリ防止剤として有機ポリハロゲン化物を含むことが必要である。適量のポリハロゲン化合物を含有することによって顕著な画像保存性の改良効果が得られる。
これらについては、特開平11-65021号の段落番号0111〜0112に記載の特許に開示されているものが挙げられる。特に特願平11-87297号の式（Ｐ）で表される有機ハロゲン化合物、特開平10-339934号の一般式（II）で表される有機ポリハロゲン化合物、特願平11-205330号に記載の有機ポリハロゲン化合物が好ましい。
【０１１１】
（ポリハロゲン化合物の説明）
以下、本発明で好ましい有機ポリハロゲン化合物について具体的に説明する。本発明の好ましいポリハロゲン化合物は下記一般式（Ｈ）で表される化合物である。
【０１１２】
一般式（Ｈ）
Ｑ−（Ｙ）ｎ−Ｃ（Ｚ₁）（Ｚ₂）Ｘ
【０１１３】
一般式（Ｈ）において、Ｑはアルキル基、アリール基またはヘテロ環基を表し、Ｙは−ＳＯ _２ −を表し、ｎは１を表し、Ｚ₁およびＺ₂はハロゲン原子を表し、Ｘは水素原子または電子吸引性基を表す。一般式（Ｈ）において、Ｑは好ましくはハメットの置換基定数σｐが正の値をとる電子吸引性基で置換されたフェニル基を表す。ハメットの置換基定数に関しては、Journal of Medicinal Chemistry,1973,Vol.16,No.11,1207-1216 等を参考にすることができる。
【０１１４】
このような電子吸引性基としては、例えばハロゲン原子（フッ素原子（σｐ値：０．０６）、塩素原子（σｐ値：０．２３）、臭素原子（σｐ値：０．２３）、ヨウ素原子（σｐ値：０．１８））、トリハロメチル基（トリブロモメチル（σｐ値：０．２９）、トリクロロメチル（σｐ値：０．３３）、トリフルオロメチル（σｐ値：０．５４））、シアノ基（σｐ値：０．６６）、ニトロ基（σｐ値：０．７８）、脂肪族・アリールもしくは複素環スルホニル基（例えば、メタンスルホニル（σｐ値：０．７２））、脂肪族・アリールもしくは複素環アシル基（例えば、アセチル（σｐ値：０．５０）、ベンゾイル（σｐ値：０．４３））、アルキニル基（例えば、Ｃ≡ＣＨ（σｐ値：０．２３））、脂肪族・アリールもしくは複素環オキシカルボニル基（例えば、メトキシカルボニル（σｐ値：０．４５）、フェノキシカルボニル（σｐ値：０．４４））、カルバモイル基（σｐ値：０．３６）、スルファモイル基（σｐ値：０．５７）、スルホキシド基、ヘテロ環基、ホスホリル基等があげられる。
σｐ値としては好ましくは０．２〜２．０の範囲で、より好ましくは０．４から１．０の範囲である。
【０１１５】
電子吸引性基として特に好ましいのは、カルバモイル基、アルコキシカルボニル基、アルキルスルホニル基、アルキルホスホリル基で、なかでもカルバモイル基が最も好ましい。
【０１１６】
Ｘは、好ましくは電子吸引性基であり、より好ましくはハロゲン原子、脂肪族・アリールもしくは複素環スルホニル基、脂肪族・アリールもしくは複素環アシル基、脂肪族・アリールもしくは複素環オキシカルボニル基、カルバモイル基、スルファモイル基であり、特に好ましくはハロゲン原子である。ハロゲン原子の中でも、好ましくは塩素原子、臭素原子、ヨウ素原子であり、更に好ましくは塩素原子、臭素原子であり、特に好ましくは臭素原子である。
Ｙは−ＳＯ ₂ −である。ｎは、１である。
【０１１７】
以下に本発明の一般式（Ｈ）の化合物の具体例を示すが、本発明はこれらに限定されるものではない。
【０１１８】
【化９】

【０１１９】
【化１０】

【０１２０】
本発明の一般式（Ｈ）で表される化合物は画像形成層の非感光性有機銀塩１モルあたり、１０^-3〜０．８モルの範囲で使用することが好ましく、より好ましくは１０^-3〜０．１モルの範囲で、さらに好ましくは５×１０^-3〜０．０５モルの範囲で使用することが好ましい。
特に本発明の高ヨウ化銀を用いた感材ではこのポリハロゲン化合物の添加量は重要であり、非感光性有機銀塩１モル当り５×１０^-3〜０．０３モル以下であることが特に好ましい。
本発明において、カブリ防止剤を感光材料に含有せしめる方法としては、前記還元剤の含有方法に記載の方法が挙げられ、有機ポリハロゲン化合物についても固体微粒子分散物で添加することが好ましい。
【０１２１】
（その他のカブリ防止剤）
その他のカブリ防止剤としては特開平11-65021号段落番号0113の水銀（II）塩、同号段落番号0114の安息香酸類、特開2000-206642号のサリチル酸誘導体、特開2000-221634号の式（Ｓ）で表されるホルマリンスカベンジャー化合物、特開平11-352624号の請求項９に係るトリアジン化合物、特開平6-11791号の一般式（III）で表される化合物、４−ヒドロキシ−６−メチル−１,３,３ａ,７−テトラザインデン等が挙げられる。
【０１２２】
本発明における熱現像感光材料はカブリ防止を目的としてアゾリウム塩を含有しても良い。アゾリウム塩としては、特開昭59-193447号記載の一般式（XI）で表される化合物、特公昭55-12581号記載の化合物、特開昭60-153039号記載の一般式（II）で表される化合物が挙げられる。アゾリウム塩は感光材料のいかなる部位に添加しても良いが、添加層としては感光性層を有する面の層に添加することが好ましく、有機銀塩含有層に添加することがさらに好ましい。
アゾリウム塩の添加時期としては塗布液調製のいかなる工程で行っても良く、有機銀塩含有層に添加する場合は有機銀塩調製時から塗布液調製時のいかなる工程でも良いが有機銀塩調製後から塗布直前が好ましい。アゾリウム塩の添加法としては粉末、溶液、微粒子分散物などいかなる方法で行っても良い。また、増感色素、還元剤、色調剤など他の添加物と混合した溶液として添加しても良い。
【０１２３】
本発明においてアゾリウム塩の添加量としてはいかなる量でも良いが、銀１モル当たり１×１０^-6モル以上２モル以下が好ましく、１×１０^-3モル以上０．５モル以下がさらに好ましい。
【０１２４】
本発明には現像を抑制あるいは促進させ現像を制御するため、分光増感効率を向上させるため、現像前後の保存性を向上させるためなどにメルカプト化合物、ジスルフィド化合物、チオン化合物を含有させることができ、特開平10-62899号の段落番号0067〜0069、特開平10-186572号の一般式（Ｉ）で表される化合物及びその具体例として段落番号0033〜0052、欧州特許公開第0803764A1号の第２０ページ第３６〜５６行、特願平11-273670号等に記載されている。中でもメルカプト置換複素芳香族化合物が好ましい。
【０１２５】
（色調剤の説明）
本発明の熱現像感光材料では色調剤の添加が好ましく、色調剤については、特開平10-62899号の段落番号0054〜0055、欧州特許公開第0803764A1号の第２１ページ第２３〜４８行、特開2000-356317号や特願2000-187298号に記載されており、特に、フタラジノン類（フタラジノン、フタラジノン誘導体もしくは金属塩；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−ジメトキシフタラジノンおよび２，３−ジヒドロ−１，４−フタラジンジオン）；フタラジノン類とフタル酸類（例えば、フタル酸、４−メチルフタル酸、４−ニトロフタル酸、フタル酸二アンモニウム、フタル酸ナトリウム、フタル酸カリウムおよびテトラクロロ無水フタル酸）との組合せ；フタラジン類（フタラジン、フタラジン誘導体もしくは金属塩；例えば４−(１−ナフチル)フタラジン、６−イソプロピルフタラジン、６−ｔ−ブチルフラタジン、６−クロロフタラジン、５，７−ジメトキシフタラジンおよび２，３−ジヒドロフタラジン）；フタラジン類とフタル酸類との組合せが好ましく、特に高ヨウ化銀との組み合わせにおいてはフタラジン類とフタル酸類の組合せが好ましい。
【０１２６】
好ましいフタラジン類の添加量としてはベヘン酸銀１モル当り０．０１モル以上０．３モル以下であり、さらに好ましくは０．０２モル以上０，２モル以下である。特に好ましくは０，０２モル以上０．１モル以下であることが好ましい。このフタラジン類の添加量は、本発明のヨウ化銀乳剤で問題となっている現像促進にとって重要である。適性な添加量の選択によって現像性と被りが両立できる。
【０１２７】
（その他の添加剤）
本発明の感光性層に用いることのできる可塑剤および潤滑剤については特開平11-65021号段落番号0117、超硬調画像形成のための超硬調化剤やその添加方法や量については、同号段落番号0118、特開平11-223898号段落番号0136〜0193、特願平11-87297号の式（Ｈ）、式（１）〜（３）、式（Ａ）、（Ｂ）の化合物、特願平11-91652号記載の一般式（III）〜（Ｖ）の化合物（具体的化合物：化２１〜化２４）、硬調化促進剤については特開平11-65021号段落番号0102、特開平11-223898号段落番号0194〜0195に記載されている。
【０１２８】
蟻酸や蟻酸塩を強いかぶらせ物質として用いるには、感光性ハロゲン化銀を含有する画像形成層を有する側に銀１モル当たり５ミリモル以下、さらには１ミリモル以下で含有することが好ましい。
【０１２９】
本発明の熱現像感光材料で超硬調化剤を用いる場合には五酸化二リンが水和してできる酸またはその塩を併用して用いることが好ましい。五酸化二リンが水和してできる酸またはその塩としては、メタリン酸（塩）、ピロリン酸（塩）、オルトリン酸（塩）、三リン酸（塩）、四リン酸（塩）、ヘキサメタリン酸（塩）などを挙げることができる。
特に好ましく用いられる五酸化二リンが水和してできる酸またはその塩としては、オルトリン酸（塩）、ヘキサメタリン酸（塩）を挙げることができる。具体的な塩としてはオルトリン酸ナトリウム、オルトリン酸二水素ナトリウム、ヘキサメタリン酸ナトリウム、ヘキサメタリン酸アンモニウムなどがある。
五酸化二リンが水和してできる酸またはその塩の使用量（感光材料１ｍ²あたりの塗布量）は感度やカブリなどの性能に合わせて所望の量でよいが、０．１〜５００ｍｇ／ｍ²が好ましく、０．５〜１００ｍｇ／ｍ²がより好ましい。
【０１３０】
（層構成の説明）
本発明における熱現像感光材料は画像形成層の付着防止などの目的で表面保護層を設けることができる。表面保護層は単層でもよいし、複数層であってもよい。表面保護層については、特開平11-65021号段落番号0119〜0120、特願2000-171936号に記載されている。
【０１３１】
本発明の表面保護層のバインダーとしてはゼラチンが好ましいがポリビニルアルコール（ＰＶＡ）を用いる若しくは併用することも好ましい。ゼラチンとしてはイナートゼラチン（例えば新田ゼラチン７５０）、フタル化ゼラチン（例えば新田ゼラチン８０１）など使用することができる。
【０１３２】
ＰＶＡとしては、特開2000-171936号の段落番号0009〜0020に記載のものがあげられ、完全けん化物のＰＶＡ−１０５、部分けん化物のＰＶＡ−２０５、ＰＶＡ−３３５、変性ポリビニルアルコールのＭＰ−２０３（以上、クラレ（株）製の商品名）などが好ましく挙げられる。
保護層（１層当たり）のポリビニルアルコール塗布量（支持体１ｍ²当たり）としては０．３〜４．０ｇ／ｍ²が好ましく、０．３〜２．０ｇ／ｍ²がより好ましい。
【０１３３】
特に寸法変化が問題となる印刷用途に本発明の熱現像感光材料を用いる場合には、表面保護層やバック層にポリマーラテックスを用いることが好ましい。
このようなポリマーラテックスについては「合成樹脂エマルジョン（奥田平、稲垣寛編集、高分子刊行会発行（１９７８））」、「合成ラテックスの応用（杉村孝明、片岡靖男、鈴木聡一、笠原啓司編集、高分子刊行会発行（１９９３））」、「合成ラテックスの化学（室井宗一著、高分子刊行会発行（１９７０））」などにも記載され、具体的にはメチルメタクリレート（３３．５質量％）／エチルアクリレート（５０質量％）／メタクリル酸（１６．５質量％）コポリマーのラテックス、メチルメタクリレート（４７．５質量％）／ブタジエン（４７．５質量％）／イタコン酸（５質量％）コポリマーのラテックス、エチルアクリレート（５０質量％）／メタクリル酸（５０質量％）のコポリマーのラテックス、メチルメタクリレート（５８．９質量％)／２−エチルヘキシルアクリレート（２５．４質量％）／スチレン（８．６質量％）／２−ヒドロキシエチルメタクリレート（５．１質量％）／アクリル酸（２．０質量％）コポリマーのラテックス、メチルメタクリレート（６４．０質量％）／スチレン（９．０質量％)／ブチルアクリレート（２０．０質量％）／２−ヒドロキシエチルメタクリレート（５．０質量％）／アクリル酸（２．０質量％）コポリマーのラテックスなどが挙げられる。
【０１３４】
さらに、表面保護層用のバインダーとして、特願平11-6872号明細書のポリマーラテックスの組み合わせ、特願平11-143058号明細書の段落番号0021〜0025に記載の技術、特願平11-6872号明細書の段落番号0027〜0028に記載の技術、特願平10-199626号明細書の段落番号0023〜0041に記載の技術を適用してもよい。
【０１３５】
表面保護層のポリマーラテックスの比率は全バインダーの１０質量％以上９０質量％以下が好ましく、特に２０質量％以上８０質量％以下が好ましい。
表面保護層（１層当たり）の全バインダー（水溶性ポリマー及びラテックスポリマーを含む）塗布量（支持体１ｍ²当たり）としては０．３〜５．０ｇ／ｍ²が好ましく、０．３〜２．０ｇ／ｍ²がより好ましい。
【０１３６】
本発明の画像形成層塗布液の調製温度は３０℃以上６５℃以下がよく、さらに好ましい温度は３５℃以上６０℃未満、より好ましい温度は３５℃以上５５℃以下である。また、ポリマーラテックス添加直後の画像形成層塗布液の温度が３０℃以上６５℃以下で維持されることが好ましい。
【０１３７】
本発明の画像形成層は、支持体上に一またはそれ以上の層で構成される。一層で構成する場合は有機銀塩、感光性ハロゲン化銀、熱現像剤である還元剤およびバインダーよりなり、必要により色調剤、被覆助剤および他の補助剤などの所望による追加の材料を含む。 二層以上で構成する場合は、第１画像形成層（通常は支持体に隣接した層）中に有機銀塩および感光性ハロゲン化銀を含み、第２画像形成層または両層中にいくつかの他の成分を含まなければならない。
多色感光性熱現像写真材料の構成は、各色についてこれらの二層の組合せを含んでよく、また、米国特許第4,708,928号に記載されているように単一層内に全ての成分を含んでいてもよい。多染料多色感光性熱現像写真材料の場合、各乳剤層は、一般に、米国特許第4,460,681号に記載されているように、各感光性層の間に官能性もしくは非官能性のバリアー層を使用することにより、互いに区別されて保持される。
【０１３８】
本発明の感光性層には色調改良、レーザー露光時の干渉縞発生防止、イラジエーション防止の観点から各種染料や顔料（例えばC.I.Pigment Blue 60、C.I.Pigment Blue 64、C.I.Pigment Blue 15:6）を用いることができる。これらについてはWO98/36322号、特開平10-268465号、同11-338098号等に詳細に記載されている。
【０１３９】
本発明の熱現像感光材料においては、アンチハレーション層を感光性層に対して光源から遠い側に設けることができる。
【０１４０】
熱現像感光材料は一般に、感光性層に加えて非感光性層を有する。非感光性層は、その配置から（１）感光性層の上（支持体よりも遠い側）に設けられる保護層、（２）複数の感光性層の間や感光性層と保護層の間に設けられる中間層、（３）感光性層と支持体との間に設けられる下塗り層、（４）感光性層の反対側に設けられるバック層に分類できる。フィルター層は、（１）または（２）の層として感光材料に設けられる。アンチハレーション層は、（３）または（４）の層として感光材料に設けられる。
【０１４１】
アンチハレーション層については特開平11-65021号段落番号0123〜0124、特開平11-223898号、同9-230531号、同10-36695号、同10-104779号、同11-231457号、同11-352625号、同11-352626号等に記載されている。
アンチハレーション層には、露光波長に吸収を有するアンチハレーション染料を含有する。露光波長が赤外域にある場合には赤外線吸収染料を用いればよく、その場合には可視域に吸収を有しない染料が好ましい。
可視域に吸収を有する染料を用いてハレーション防止を行う場合には、画像形成後には染料の色が実質的に残らないようにすることが好ましく、熱現像の熱により消色する手段を用いることが好ましく、特に非感光性層に熱消色染料と塩基プレカーサーとを添加してアンチハレーション層として機能させることが好ましい。
これらの技術については特開平11-231457号等に記載されている。
【０１４２】
消色染料の添加量は、染料の用途により決定する。一般には、目的とする波長で測定したときの光学濃度（吸光度）が０．１を越える量で使用する。光学濃度は、０．２〜２であることが好ましい。このような光学濃度を得るための染料の使用量は、一般に０．００１〜１ｇ／ｍ²程度である。
【０１４３】
なお、このように染料を消色すると、熱現像後の光学濃度を０．１以下に低下させることができる。二種類以上の消色染料を、熱消色型記録材料や熱現像感光材料において併用してもよい。同様に、二種類以上の塩基プレカーサーを併用してもよい。
このような消色染料と塩基プレカーサーを用いる熱消色においては、特開平11-352626号に記載のような塩基プレカーサーと混合すると融点を３℃（ｄｅｇ）以上降下させる物質（例えば、ジフェニルスルフォン、4-クロロフェニル（フェニル）スルフォン）を併用することが熱消色性等の点で好ましい。
【０１４４】
本発明においては、銀色調、画像の経時変化を改良する目的で３００〜４５０ｎｍに吸収極大を有する着色剤を添加することができる。このような着色剤は、特開昭62-210458号、同63-104046号、同63-103235号、同63-208846号、同63-306436号、同63-314535号、特開平01-61745号、特願平11-276751号などに記載されている。
このような着色剤は、通常、０．１ｍｇ／ｍ²〜１ｇ／ｍ²の範囲で添加され、添加する層としては感光性層の反対側に設けられるバック層が好ましい。
【０１４５】
本発明における熱現像感光材料は、支持体の一方の側に少なくともハロゲン化銀乳剤を含む感光性層を有し、他方の側にバック層を有する、いわゆる片面感光材料であることが好ましい。
【０１４６】
本発明において、搬送性改良のためにマット剤を添加することが好ましく、マット剤については、特開平11-65021号段落番号0126〜0127に記載されている。マット剤は感光材料１ｍ²当たりの塗布量で示した場合、好ましくは１〜４００ｍｇ／ｍ²、より好ましくは５〜３００ｍｇ／ｍ²である。
また、乳剤面のマット度は、画像部に小さな白抜けが生じ、光漏れが発生するいわゆる星屑故障が生じなければいかようでも良いが、ベック平滑度が３０秒以上２０００秒以下が好ましく、特に４０秒以上１５００秒以下が好ましい。ベック平滑度は、日本工業規格（ＪＩＳ）P8119「紙および板紙のベック試験器による平滑度試験方法」およびTAPPI標準法T479により容易に求めることができる。
【０１４７】
本発明においてバック層のマット度としてはベック平滑度が１２００秒以下１０秒以上が好ましく、８００秒以下２０秒以上が好ましく、さらに好ましくは５００秒以下４０秒以上である。
【０１４８】
本発明において、マット剤は感光材料の最外表面層もしくは最外表面層として機能する層、あるいは外表面に近い層に含有されるのが好ましく、またいわゆる保護層として作用する層に含有されることが好ましい。
【０１４９】
本発明に適用することのできるバック層については特開平11-65021号段落番号0128〜0130に記載されている。
【０１５０】
本発明の熱現像感光材料は、熱現像処理前の膜面ｐＨが７．０以下であることが好ましく、さらに好ましくは６．６以下である。その下限には特に制限はないが、３程度である。最も好ましいｐＨ範囲は４〜６．２の範囲である。
膜面ｐＨの調節はフタル酸誘導体などの有機酸や硫酸などの不揮発性の酸、アンモニアなどの揮発性の塩基を用いることが、膜面ｐＨを低減させるという観点から好ましい。特にアンモニアは揮発しやすく、塗布する工程や熱現像される前に除去できることから低膜面ｐＨを達成する上で好ましい。
また、水酸化ナトリウムや水酸化カリウム、水酸化リチウム等の不揮発性の塩基とアンモニアを併用することも好ましく用いられる。なお、膜面ｐＨの測定方法は、特願平11-87297号明細書の段落番号０１２３に記載されている。
【０１５１】
本発明の感光性層、保護層、バック層など各層には硬膜剤を用いても良い。硬膜剤の例としてはT.H.James著“THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION”(Macmillan Publishing Co., Inc.刊、1977年刊)77頁から87頁に記載の各方法があり、クロムみょうばん、２,４−ジクロロ−６−ヒドロキシ−ｓ−トリアジンナトリウム塩、Ｎ,Ｎ−エチレンビス（ビニルスルフォンアセトアミド）、Ｎ,Ｎ−プロピレンビス（ビニルスルフォンアセトアミド）の他、同書７８頁など記載の多価金属イオン、米国特許4,281,060号、特開平6-208193号などのポリイソシアネート類、米国特許4,791,042号などのエポキシ化合物類、特開昭62-89048号などのビニルスルホン系化合物類が好ましく用いられる。
【０１５２】
硬膜剤は溶液として添加され、この溶液の保護層塗布液中への添加時期は、塗布する１８０分前から直前、好ましくは６０分前から１０秒前であるが、混合方法及び混合条件については本発明の効果が十分に現れる限りにおいては特に制限はない。
具体的な混合方法としては添加流量とコーターへの送液量から計算した平均滞留時間を所望の時間となるようにしたタンクでの混合する方法やN.Harnby、M.F.Edwards、A.W.Nienow著、高橋幸司訳“液体混合技術”(日刊工業新聞社刊、1989年)の第８章などに記載されているスタチックミキサーなどを使用する方法がある。
【０１５３】
本発明に適用できる界面活性剤については特開平11-65021号段落番号0132、溶剤については同号段落番号0133、支持体については同号段落番号0134、帯電防止又は導電層については同号段落番号0135、カラー画像を得る方法については同号段落番号0136に、滑り剤については特開平11-84573号段落番号0061〜0064や特願平11-106881号段落番号0049〜0062記載されている。
【０１５４】
透明支持体は二軸延伸時にフィルム中に残存する内部歪みを緩和させ、熱現像処理中に発生する熱収縮歪みをなくすために、１３０〜１８５℃の温度範囲で熱処理を施したポリエステル、特にポリエチレンテレフタレートが好ましく用いられる。
医療用の熱現像感光材料の場合、透明支持体は青色染料（例えば、特開平8-240877号実施例記載の染料-1）で着色されていてもよいし、無着色でもよい。
【０１５５】
支持体には、特開平11-84574号の水溶性ポリエステル、同10-186565号のスチレンブタジエン共重合体、特開2000-39684号や特願平11-106881号段落番号0063〜0080の塩化ビニリデン共重合体などの下塗り技術を適用することが好ましい。また、帯電防止層若しくは下塗りについて特開昭56-143430号、同56-143431号、同58-62646号、同56-120519号、特開平11-84573号の段落番号0040〜0051、米国特許第5,575,957号、特開平11-223898号の段落番号0078〜0084に記載の技術を適用することができる。
【０１５６】
熱現像感光材料は、モノシート型（受像材料のような他のシートを使用せずに、熱現像感光材料上に画像を形成できる型）であることが好ましい。
【０１５７】
熱現像感光材料には、さらに、酸化防止剤、安定化剤、可塑剤、紫外線吸収剤あるいは被覆助剤を添加してもよい。各種の添加剤は、感光性層あるいは非感光性層のいずれかに添加する。それらについてWO98/36322号、EP803764A1号、特開平10-186567号、同10-18568号等を参考にすることができる。
【０１５８】
本発明における熱現像感光材料はいかなる方法で塗布されても良い。具体的には、エクストルージョンコーティング、スライドコーティング、カーテンコーティング、浸漬コーティング、ナイフコーティング、フローコーティング、または米国特許第2,681,294号に記載の種類のホッパーを用いる押出コーティングを含む種々のコーティング操作が用いられ、Stephen F. Kistler、Petert M. Schweizer著“LIQUID FILM COATING”(CHAPMAN & HALL社刊、1997年)399頁から536頁記載のエクストルージョンコーティング、またはスライドコーティング好ましく用いられ、特に好ましくはスライドコーティングが用いられる。スライドコーティングに使用されるスライドコーターの形状の例は同書427頁のFigure 11b.1にある。また、所望により同書399頁から536頁記載の方法、米国特許第2,761,791号および英国特許第837,095号に記載の方法により２層またはそれ以上の層を同時に被覆することができる。
【０１５９】
本発明における有機銀塩含有層塗布液は、いわゆるチキソトロピー流体であることが好ましい。この技術については特開平11-52509号を参考にすることができる。
本発明における有機銀塩含有層塗布液は剪断速度０．１Ｓ^-1における粘度は４００ｍＰａ・ｓ以上１０００００ｍＰａ・ｓ以下が好ましく、さらに好ましくは５００ｍＰａ・s以上２００００ｍＰａ・ｓ以下である。
また、剪断速度１０００Ｓ^-1においては１ｍＰａ・ｓ以上２００ｍＰａ・ｓ以下が好ましく、さらに好ましくは５ｍＰａ・ｓ以上８０ｍＰａ・ｓ以下である。
【０１６０】
本発明の熱現像感光材料は成膜性を向上させるために塗布、乾燥直後に加熱処理をすることが好ましい。加熱処理の温度は膜面温度で６０℃〜１００℃の範囲が好ましく、加熱時間は１秒〜６０秒の範囲が好ましい。より好ましい範囲は膜面温度が７０℃〜９０℃、加熱時間が２秒〜１０秒の範囲である。本発明の好ましい加熱処理の方法は特開２００２−１０７８７２号に記載されている。
【０１６１】
本発明の熱現像感光材料に用いることのできる技術としては、EP803764A1号、EP883022A1号、WO98/36322号、特開昭56-62648号、同58-62644号、特開平9-43766、同9-281637、同9-297367号、同9-304869号、同9-311405号、同9-329865号、同10-10669号、同10-62899号、同10-69023号、同10-186568号、同10-90823号、同10-171063号、同10-186565号、同10-186567号、同10-186569号〜同10-186572号、同10-197974号、同10-197982号、同10-197983号、同10-197985号〜同10-197987号、同10-207001号、同10-207004号、同10-221807号、同10-282601号、同10-288823号、同10-288824号、同10-307365号、同10-312038号、同10-339934号、同11-7100号、同11-15105号、同11-24200号、同11-24201号、同11-30832号、同11-84574号、同11-65021号、同11-109547号、同11-125880号、同11-129629号、同11-133536号〜同11-133539号、同11-133542号、同11-133543号、同11-223898号、同11-352627号、同11-305377号、同11-305378号、同11-305384号、同11-305380号、同11-316435号、同11-327076号、同11-338096号、同11-338098号、同11-338099号、同11-343420号、特願2000-187298号、同2000-10229号、同2000-47345号、同2000-206642号、同2000-98530号、同2000-98531号、同2000-112059号、同2000-112060号、同2000-112104号、同2000-112064号、同2000-171936号も挙げられる。
【０１６２】
（包装材料の説明）
本発明の感光材料は生保存時の写真性能の変動を押さえるため、もしくはカール、巻癖などを改良するために、酸素透過率および／または水分透過率の低い包装材料で包装することが好ましい。該酸素透過率および／または水分透過率の低い包装材料の具体例としては、たとえば特開平８−２５４７９３号。特開２０００−２０６６５３号明細書に記載されている包装材料である。
【０１６３】
（熱現像の説明）
本発明の熱現像感光材料はいかなる方法で現像されても良いが、通常イメージワイズに露光した熱現像感光材料を昇温して現像される。好ましい現像温度としては８０〜２５０℃であり、さらに好ましくは１００〜１４０℃である。特に１１０〜１３０℃の現像温度で現像される条件において本発明の効果は顕著に発現する。さらに好ましくは１１５℃以上１３０以下である。
現像温度１１０℃以下では本発明で用いられる高ヨウ化銀乳剤は、従来知られている高臭化銀乳剤と同程度の現像進行性を示す。しかしながら現像温度を１１０℃以上に上げると従来の高ヨウ化銀乳剤を用いた感光材料は、高臭化銀乳剤に比べて著しい現像進行性の悪化を伴うものであったが、本発明では、このような現像条件下においても好ましい現像進行性を確保することができる。
現像時間としては１〜６０秒が好ましく、５〜３０秒がさらに好ましく、１０〜２０秒が特に好ましい。
【０１６４】
熱現像の方式としてはプレートヒーター方式が好ましい。プレートヒーター方式による熱現像方式とは特開平11-133572号に記載の方法が好ましく、潜像を形成した熱現像感光材料を熱現像部にて加熱手段に接触させることにより可視像を得る熱現像装置であって、前記加熱手段がプレートヒータからなり、かつ前記プレートヒータの一方の面に沿って複数個の押えローラが対向配設され、前記押えローラと前記プレートヒータとの間に前記熱現像感光材料を通過させて熱現像を行うことを特徴とする熱現像装置である。プレートヒータを２〜６段に分けて先端部については１〜１０℃程度温度を下げることが好ましい。
このような方法は特開昭54-30032号にも記載されており、熱現像感光材料に含有している水分や有機溶媒を系外に除外させることができ、また、急激に熱現像感光材料が加熱されることでの熱現像感光材料の支持体形状の変化を押さえることもできる。
【０１６５】
本発明の感光材料は、露光光源としてレーザー光が好ましい。本発明で好ましく用いられる高ヨウ化銀乳剤は、従来その感度が低くて問題であった。しかし本発明の高ヨウ化銀乳剤は、レーザー光の様な高照度な光で露光することにより少ないエネルギーで画像記録できることが分かった。このような強い光で短時間に書き込むことによって目標の感度を達成することができる。
【０１６６】
特に最高濃度を出すような露光量を与える場合、感光材料表面の好ましい照度は０．１Ｗ／ｍｍ²以上１００Ｗ／ｍｍ²以下であるような照度で露光することが好ましい。より好ましくは０．５Ｗ／ｍｍ²以上５０Ｗ／ｍｍ²以下である。さらに好ましくは１Ｗ／ｍｍ²以上５０Ｗ／ｍｍ²以下であることが好ましい。
【０１６７】
本発明によるレーザー光としては、ガスレーザー(Ａｒ⁺、Ｈｅ−Ｎｅ)、ＹＡＧレーザー、色素レーザー、半導体レーザーなどが好ましい。また、半導体レーザーと第２高調波発生素子などを用いることもできる。好ましくは赤〜赤外発光のガス若しくは半導体レーザーである。好ましいレーザー光の波長は６００ｎｍ以上９００ｎｍ以下である。特に好ましくは６２０ｎｍ以上８５０ｎｍ以下である。
レーザー光は高周波重畳などの方法によって縦マルチに発振している事も好ましく用いられる。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。
【０１６８】
露光部及び熱現像部を備えた医療用のレーザーイメージャーとしては富士メディカルドライレーザーイメージャーＦＭ−ＤＰＬを挙げることができる。ＦＭ−ＤＰＬに関しては、Fuji Medical Review No.8,page 39〜55に記載されており、それらの技術は本発明の熱現像感光材料のレーザーイメージャーとして適用することは言うまでもない。また、ＤＩＣＯＭ規格に適応したネットワークシステムとして富士メディカルシステムが提案した「ＡＤ network」の中でのレーザーイメージャー用の熱現像感光材料としても適用することができる。
【０１６９】
本発明の熱現像感光材料は、銀画像による黒白画像を形成し、医療診断用の熱現像感光材料、工業写真用熱現像感光材料、印刷用熱現像感光材料、ＣＯＭ用の熱現像感光材料として使用されることが好ましい。
【０１７０】
【実施例】
以下、本発明を実施例によって具体的に説明するが、本発明はこれらに限定されるものではない。
【０１７１】
実施例１
（ＰＥＴ支持体の作成）
テレフタル酸とエチレングリコールを用い、常法に従い固有粘度IV＝０．６６（フェノール／テトラクロルエタン＝６／４（重量比）中２５℃で測定）のＰＥＴを得た。これをペレット化した後１３０℃で４時間乾燥し、３００℃で溶融後Ｔ型ダイから押し出して急冷し、熱固定後の膜厚が１７５μｍになるような厚みの未延伸フィルムを作成した。
【０１７２】
これを、周速の異なるロールを用い３．３倍に縦延伸、ついでテンターで４．５倍に横延伸を実施した。この時の温度はそれぞれ、１１０℃、１３０℃であった。この後、２４０℃で２０秒間熱固定後、これと同じ温度で横方向に４％緩和した。この後テンターのチャック部をスリットした後、両端にナール加工を行い、４ｋｇ／ｃｍ²で巻き取り、厚み１７５μｍのロールを得た。
【０１７３】
（表面コロナ処理）
ピラー社製ソリッドステートコロナ処理機６ＫＶＡモデルを用い、支持体の両面を室温下において２０ｍ／分で処理した。この時の電流、電圧の読み取り値から、支持体には０．３７５ｋＶ・Ａ・分／ｍ²の処理がなされていることがわかった。この時の処理周波数は９．６ｋＨｚ、電極と誘電体ロールのギャップクリアランスは１．６ｍｍであった。
【０１７４】
（下塗り支持体の作成）
（１）下塗層塗布液の作成
処方▲１▼（感光層側下塗り層用）
高松油脂(株)製ペスレジンA-520(30質量％溶液) 59ｇ
ポリエチレングリコールモノノニルフェニルエーテル
(平均エチレンオキシド数＝8.5) 10質量％溶液 5.4ｇ
綜研化学(株)製 MP-1000(ポリマー微粒子、平均粒径0.4μm) 0.91g
蒸留水 935ml
【０１７５】
処方▲２▼（バック面第１層用）
スチレン−ブタジエン共重合体ラテックス 158ｇ
（固形分40質量％、スチレン／ブタジエン重量比＝68/32）
２，４−ジクロロ−６−ヒドロキシ−Ｓ−
トリアジンナトリウム塩 ８質量％水溶液 20g
ラウリルベンゼンスルホン酸ナトリウムの１質量％水溶液 10ml
蒸留水 854ml
【０１７６】
処方▲３▼（バック面側第２層用）
SnO₂/SbO (9/1質量比、平均粒径0.038μm、17質量％分散物） 84ｇ
ゼラチン(10質量%水溶液) 89.2ｇ
信越化学(株)製 メトローズTC-5(2質量%水溶液) 8.6g
綜研化学(株)製 MP-1000 0.01g
ドデシルベンゼンスルホン酸ナトリウムの１質量％水溶液 10ml
NaOH(1質量%) 6ml
プロキセル（ＩＣＩ社製） 1ml
蒸留水 805ml
【０１７７】
(下塗り支持体の作成)
上記厚さ１７５μｍの２軸延伸ポリエチレンテレフタレート支持体の両面それぞれに、上記コロナ放電処理を施した後、片面（感光性層面）に上記下塗り塗布液処方▲１▼をワイヤーバーでウエット塗布量が６．６ｍｌ／ｍ²（片面当たり）になるように塗布して１８０℃で５分間乾燥し、ついでこの裏面（バック面）に上記下塗り塗布液処方▲２▼をワイヤーバーでウエット塗布量が５．７ｍｌ／ｍ²になるように塗布して１８０℃で５分間乾燥し、更に裏面（バック面）に上記下塗り塗布液処方▲３▼をワイヤーバーでウエット塗布量が７．７ｍｌ／ｍ²になるように塗布して１８０℃で６分間乾燥して下塗り支持体を作成した。
【０１７８】
（バック面塗布液の調製）
（塩基プレカーサーの固体微粒子分散液（a）の調製）
塩基プレカーサー化合物１１を６４ｇ、ジフェニルスルフォンを２８ｇおよび花王（株）製界面活性剤デモールＮ １０ｇを蒸留水２２０ｍｌと混合し、混合液をサンドミル（１／４ Gallonサンドグラインダーミル、アイメックス（株）製）を用いてビーズ分散し、平均粒子径０．２μｍの塩基プレカーサー化合物の固体微粒子分散液（ａ）を得た。
【０１７９】
（染料固体微粒子分散液の調製）
シアニン染料化合物１３を９．６ｇおよびｐ−ドデシルベンゼンスルフォン酸ナトリウム５．８ｇを蒸留水３０５ｍｌと混合し、混合液をサンドミル（１／４ Gallonサンドグラインダーミル、アイメックス（株）製）を用いてビーズ分散して平均粒子径０．２μｍの染料固体微粒子分散液を得た。
【０１８０】
（ハレーション防止層塗布液の調製）
ゼラチン１７ｇ、ポリアクリルアミド９．６ｇ、上記塩基プレカーサーの固体微粒子分散液（（ａ）７０ｇ、上記染料固体微粒子分散液５６ｇ、単分散ポリメチルメタクリレート微粒子（平均粒子サイズ８μｍ、粒径標準偏差０．４）１．５ｇ、ベンゾイソチアゾリノン０．０３ｇ、ポリエチレンスルフォン酸ナトリウム２．２ｇ、青色染料化合物１４を０．２ｇ、黄色染料化合物１５を３．９ｇ、水を８４４ｍｌ混合し、ハレーション防止層塗布液を調製した。
【０１８１】
（バック面保護層塗布液の調製）
容器を４０℃に保温し、ゼラチン５０ｇ、ポリスチレンスルフォン酸ナトリウム０．２ｇ、Ｎ,Ｎ−エチレンビス（ビニルスルフォンアセトアミド）２．４ｇ、t-オクチルフェノキシエトキシエタンスルフォン酸ナトリウム１ｇ、ベンゾイソチアゾリノン３０ｍｇ、フッ素系界面活性剤（Ｆ−１：Ｎ−パーフルオロオクチルスルフォニル−Ｎ−プロピルアラニンカリウム塩）３７ｍｇ、フッ素系界面活性剤（Ｆ−２：ポリエチレングリコールモノ（Ｎ−パーフルオロオクチルスルホニル−Ｎ−プロピル−２−アミノエチル）エーテル[エチレンオキサイド平均重合度１５]）０．１５ｇ、フッ素系界面活性剤（Ｆ−３）６４ｍｇ、フッ素系界面活性剤（Ｆ−４）３２ｍｇ、アクリル酸／エチルアクリレート共重合体（共重合重量比５／９５）８．８ｇ、エアロゾールＯＴ（アメリカンサイアナミド社製）０．６ｇ、流動パラフィン乳化物を流動パラフィンとして１．８ｇ、水を９５０ｍｌ混合してバック面保護層塗布液とした。
【０１８２】
（ハロゲン化銀乳剤の調製）
≪ハロゲン化銀乳剤１の調製≫
蒸留水１４２０ｍｌに１質量％ヨウ化カリウム溶液４．３ｍｌを加え、さらに０．５ｍｏｌ／Ｌ濃度の硫酸を３．５ｍｌ、フタル化ゼラチン３６．７ｇを添加した液をステンレス製反応壺中で攪拌しながら、４２℃に液温を保ち、硝酸銀２２．２２ｇに蒸留水を加え１９５．６ｍｌに希釈した溶液Ａとヨウ化カリウム２１．８ｇを蒸留水にて容量２１８ｍｌに希釈した溶液Ｂを一定流量で９分間かけて全量添加した。その後、３．５質量％の過酸化水素水溶液を１０ｍｌ添加し、さらにベンツイミダゾールの１０質量％水溶液を１０．８ｍｌ添加した。
【０１８３】
さらに、硝酸銀５１．８６ｇに蒸留水を加えて３１７．５ｍｌに希釈した溶液Ｃとヨウ化カリウム６０ｇを蒸留水にて容量６００ｍｌに希釈した溶液Ｄを、溶液Ｃは一定流量で１２０分間かけて全量添加し、溶液ＤはｐＡｇを８．１に維持しながらコントロールドダブルジェット法で添加した。銀１モルあたり１×１０^-4モルになるよう六塩化イリジウム（III）酸カリウム塩を溶液Ｃおよび溶液Ｄを添加しはじめてから１０分後に全量添加した。また、
溶液Ｃの添加終了の５秒後に六シアン化鉄（II）カリウム水溶液を銀1モル当たり３×１０^-4モル全量添加した。０．５ｍｏｌ／Ｌ濃度の硫酸を用いてｐＨを３．８に調整し、攪拌を止め、沈降／脱塩／水洗工程をおこなった。１ｍｏｌ／Ｌ濃度の水酸化ナトリウムを用いてｐＨ５．９に調整し、ｐＡｇ８．０のハロゲン化銀分散物を作成した。
【０１８４】
上記ハロゲン化銀分散物を攪拌しながら３８℃に維持して、０．３４質量％の１,２−ベンゾイソチアゾリン−３−オンのメタノール溶液を５ｍｌ加え、４０分後に分光増感色素Ａと増感色素Ｂのモル比で１：１のメタノール溶液を銀1モル当たり増感色素ＡとＢの合計として１．２×１０^-3モル加え、１分後に４７℃に昇温した。
昇温の２０分後にベンゼンチオスルフォン酸ナトリウムをメタノール溶液で銀１モルに対して７．６×１０^-5モル加え、さらに５分後にテルル増感剤Ｂをメタノール溶液で銀１モル当たり２．９×１０^-4モル加えて９１分間熟成した。
Ｎ，Ｎ'−ジヒドロキシ−Ｎ"−ジエチルメラミンの０．８質量％メタノール溶液１．３ｍｌを加え、さらに４分後に、５−メチル−２−メルカプトベンヅイミダゾールをメタノール溶液で銀１モル当たり４．８×１０^-3モル及び１−フェニル−２−ヘプチル−５−メルカプト−１,３,４−トリアゾールをメタノール溶液で銀１モルに対して５．４×１０^-3モルおよび１−（３−メチルウレイド）−５−メルカプトテトラゾールナトリウム塩を水溶液で銀１モルに対して８．５×１０^-3モル添加して、ハロゲン化銀乳剤１を作成した。
【０１８５】
調製できたハロゲン化銀乳剤中の粒子は、平均球相当径０．０４０μｍ、球相当径の変動係数７８％の純ヨウ化銀粒子であった。粒子サイズ等は、電子顕微鏡を用い１０００個の粒子の平均から求めた。
【０１８６】
≪塗布液用混合乳剤Ａの調製≫
ハロゲン化銀乳剤１を溶解し、ベンゾチアゾリウムヨーダイドを１質量％水溶液にて銀１モル当たり７×１０^-3モル添加した。さらに塗布液用混合乳剤１ｋｇあたりハロゲン化銀の含有量が銀として３８．２ｇとなるように加水し、塗布液用混合乳剤１ｋｇあたり０．３４ｇとなるように１−（３−メチルウレイド）−５−メルカプトテトラゾールナトリウム塩を添加した。
【０１８７】
≪脂肪酸銀（有機銀塩）分散物の調製≫
ヘンケル社製ベヘン酸（製品名Edenor C22-85R）８７．６Ｋｇ、蒸留水４２３Ｌ、５ｍｏｌ／Ｌ濃度のＮａＯＨ水溶液４９．２Ｌ、tert−ブタノール１２０Ｌを混合し、７５℃にて１時間攪拌し反応させ、ベヘン酸ナトリウム溶液を得た。別に、硝酸銀４０．４ｋｇの水溶液２０６．２Ｌ（ｐＨ４．０）を用意し、１０℃にて保温した。６３５Ｌの蒸留水と３０Ｌのtert−ブタノールを入れた反応容器を３０℃に保温し、十分に撹拌しながら先のベヘン酸ナトリウム溶液の全量と硝酸銀水溶液の全量を流量一定でそれぞれ９３分１５秒と９０分かけて添加した。
このとき、硝酸銀水溶液添加開始後１１分間は硝酸銀水溶液のみが添加されるようにし、そのあとベヘン酸ナトリウム溶液を添加開始し、硝酸銀水溶液の添加終了後１４分１５秒間はベヘン酸ナトリウム溶液のみが添加されるようにした。
【０１８８】
このとき、反応容器内の温度は３０℃とし、液温度が一定になるように外温コントロールした。また、ベヘン酸ナトリウム溶液の添加系の配管は、２重管の外側に温水を循環させる事により保温し、添加ノズル先端の出口の液温度が７５℃になるよう調製した。また、硝酸銀水溶液の添加系の配管は、２重管の外側に冷水を循環させることにより保温した。ベヘン酸ナトリウム溶液の添加位置と硝酸銀水溶液の添加位置は撹拌軸を中心として対称的な配置とし、また反応液に接触しないような高さに調製した。
【０１８９】
ベヘン酸ナトリウム溶液を添加終了後、そのままの温度で２０分間撹拌放置し、３０分かけて３５℃に昇温し、その後２１０分熟成を行った。熟成終了後直ちに、遠心濾過で固形分を濾別し、固形分を濾過水の伝導度が３０μＳ／ｃｍになるまで水洗した。こうして脂肪酸銀塩を得た。得られた固形分は、乾燥させないでウエットケーキとして保管した。
【０１９０】
得られたベヘン酸銀粒子の形態を電子顕微鏡撮影により評価したところ、平均値でａ＝０．１４μｍ、ｂ＝０．４μｍ、ｃ＝０．６μｍ、平均アスペクト比５．２、平均球相当径０．５２μｍ、球相当径の変動係数１５％のりん片状の結晶であった。（ａ,ｂ,ｃは本文の規定）
【０１９１】
乾燥固形分２６０Ｋｇ相当のウエットケーキに対し、ポリビニルアルコール（商品名：ＰＶＡ−２１７）１９．３Ｋｇおよび水を添加し、全体量を１０００Ｋｇとしてからディゾルバー羽根でスラリー化し、更にパイプラインミキサー（みづほ工業製：ＰＭ−１０型）で予備分散した。
【０１９２】
次に予備分散済みの原液を分散機（商品名：マイクロフルイダイザーＭ−６１０、マイクロフルイデックス・インターナショナル・コーポレーション製、Ｚ型インタラクションチャンバー使用）の圧力を１２６０ｋｇ／ｃｍ²に調節して、三回処理し、ベヘン酸銀分散物を得た。冷却操作は蛇管式熱交換器をインタラクションチャンバーの前後に各々装着し、冷媒の温度を調節することで１８℃の分散温度に設定した。
【０１９３】
（還元剤分散物の調製）
≪還元剤錯体−３分散物の調製≫
還元剤錯体−３（２,２'−メチレンビス−(４−エチル−６−tert−ブチルフェノール）とトリフェニルホスフィンオキシドの１：１錯体）１０Ｋｇ、トリフェニルホスフィンオキシド０．１２Ｋｇおよび変性ポリビニルアルコール（クラレ（株）製、ポバールＭＰ２０３）の１０質量％水溶液１６Ｋｇに、水７．２Ｋｇを添加して、良く混合してスラリーとした。このスラリーをダイアフラムポンプで送液し、平均直径０．５ｍｍのジルコニアビーズを充填した横型サンドミル（ＵＶＭ−２：アイメックス（株）製）にて４時間３０分分散したのち、ベンゾイソチアゾリノンナトリウム塩０．２ｇと水を加えて還元剤の濃度が２５質量％になるように調製し、還元剤錯体−３分散物を得た。
こうして得た還元剤錯体分散物に含まれる還元剤錯体粒子はメジアン径０．４６μｍ、最大粒子径１．６μｍ以下であった。得られた還元剤錯体分散物は孔径３．０μｍのポリプロピレン製フィルターにてろ過を行い、ゴミ等の異物を除去して収納した。
【０１９４】
（ポリハロゲン化合物の調製）
≪有機ポリハロゲン化合物−２分散物の調製≫
有機ポリハロゲン化合物−２（トリブロモメタンスルホニルベンゼン）１０Ｋｇと変性ポリビニルアルコール（クラレ（株）製ポバールＭＰ２０３）の２０質量％水溶液１０Ｋｇと、トリイソプロピルナフタレンスルホン酸ナトリウムの２０質量％水溶液０．４Ｋｇと、水１４Ｋｇを添加して、良く混合してスラリーとした。
このスラリーをダイアフラムポンプで送液し、平均直径０．５ｍｍのジルコニアビーズを充填した横型サンドミル（ＵＶＭ−２：アイメックス（株）製）にて５時間分散したのち、ベンゾイソチアゾリノンナトリウム塩０．２ｇと水を加えて有機ポリハロゲン化合物の濃度が２６質量％になるように調製し、有機ポリハロゲン化合物−２分散物を得た。
こうして得たポリハロゲン化合物分散物に含まれる有機ポリハロゲン化合物粒子はメジアン径０．４１μｍ、最大粒子径２．０μｍ以下であった。得られた有機ポリハロゲン化合物分散物は孔径１０．０μｍのポリプロピレン製フィルターにてろ過を行い、ゴミ等の異物を除去して収納した。
【０１９５】
≪有機ポリハロゲン化合物−３分散物の調製≫
有機ポリハロゲン化合物−３（Ｎ−ブチル−３−トリブロモメタンスルホニルベンズアミド）１０Ｋｇと変性ポリビニルアルコール（クラレ（株）製ポバールＭＰ２０３）の１０質量％水溶液２０Ｋｇと、トリイソプロピルナフタレンスルホン酸ナトリウムの２０質量％水溶液０．４Ｋｇと、水８Ｋｇを添加して、良く混合してスラリーとした。
このスラリーをダイアフラムポンプで送液し、平均直径０．５ｍｍのジルコニアビーズを充填した横型サンドミル（ＵＶＭ−２：アイメックス（株）製）にて５時間分散したのち、ベンゾイソチアゾリノンナトリウム塩０．２ｇと水を加えて有機ポリハロゲン化合物の濃度が２５質量％になるように調製した。この分散液を４０℃で５時間加温し、有機ポリハロゲン化合物−３分散物を得た。
こうして得たポリハロゲン化合物分散物に含まれる有機ポリハロゲン化合物粒子はメジアン径０．３６μｍ、最大粒子径１．５μｍ以下であった。得られた有機ポリハロゲン化合物分散物は孔径３．０μｍのポリプロピレン製フィルターにてろ過を行い、ゴミ等の異物を除去して収納した。
【０１９６】
≪フタラジン化合物−１溶液の調製≫
８Ｋｇのクラレ（株）製変性ポリビニルアルコールＭＰ２０３を水１７４．５７Ｋｇに溶解し、次いでトリイソプロピルナフタレンスルホン酸ナトリウムの２０質量％水溶液３．１５Ｋｇとフタラジン化合物−１（６−イソプロピルフタラジン）の７０質量％水溶液１４．２８Ｋｇを添加し、フタラジン化合物−１の５質量％溶液を調製した。
【０１９７】
≪メルカプト化合物−１水溶液の調製≫
メルカプト化合物−１（１−（３−スルホフェニル）−５−メルカプトテトラゾールナトリウム塩）７ｇを水９９３ｇに溶解し、０．７質量％の水溶液とした。
【０１９８】
≪顔料−１分散物の調製≫
C.I.Pigment Blue ６０を６４ｇと花王（株）製デモールＮを６．４ｇに水２５０ｇを添加し良く混合してスラリーとした。平均直径０．５ｍｍのジルコニアビーズ８００ｇを用意してスラリーと一緒にベッセルに入れ、分散機（１／４Ｇサンドグラインダーミル：アイメックス（株）製）にて２５時間分散し、顔料−１分散物を得た。
こうして得た顔料分散物に含まれる顔料粒子は平均粒径０．２１μｍであった。
【０１９９】
≪ＳＢＲラテックス液の調製≫
Ｔｇ＝２３℃のＳＢＲラテックスは以下により調整した。
前記の高Ｔｇラテックス合成例と同様にして、重合開始剤として過硫酸アンモニウム、乳化剤としてアニオン界面活性剤を使用し、スチレン７０．５質量、ブタジエン２６．５質量およびアクリル酸３質量を乳化重合させた後、８０℃で８時間エージングを行った。
その後４０℃まで冷却し、アンモニア水によりｐＨ７．０とし、さらに三洋化成（株）製サンデットＢＬを０．２２％になるように添加した。次に５％水酸化ナトリウム水溶液を添加しｐＨ８．３とし、さらにアンモニア水によりｐＨ８．４になるように調整した。このとき使用したＮａ⁺イオンとＮＨ₄ ⁺イオンのモル比は１：２．３であった。
さらに、この液１Ｋｇ対してベンゾイソチアゾリンノンナトリウム塩７％水溶液を０．１５ｍｌ添加しＳＢＲラテックス液を調製した。
【０２００】
（ＳＢＲラテックス：-St(70.5)-Bu(26.5)-AA(3)-のラテックス） Ｔｇ２３℃平均粒径０．１μｍ、濃度４３質量％、２５℃６０%ＲＨにおける平衡含水率０．６質量％、イオン伝導度４．２ｍＳ／ｃｍ（イオン伝導度の測定は東亜電波工業(株)製伝導度計ＣＭ−３０Ｓ使用し、ラテックス原液（４３質量％）を２５℃にて測定)、ｐＨ８．４
Ｔｇの異なるＳＢＲラテックスはスチレン、ブタジエンの比率を適宜変更し、同様の方法により調整した。
【０２０１】
≪乳剤層（感光性層）塗布液−１の調製≫
上記で得た脂肪酸銀分散物１０００ｇ、水１０４ｍｌ、顔料−１分散物３０ｇ、有機ポリハロゲン化合物−２分散物６．３ｇ、有機ポリハロゲン化合物−３分散物２０．７ｇ、フタラジン化合物−１溶液１７３ｇ、ＳＢＲラテックス（Ｔｇ：２３℃）液１０８２ｇ、還元剤錯体−３分散物２５８ｇ、メルカプト化合物−１溶液９ｇを順次添加し、塗布直前にハロゲン化銀混合乳剤Ａの有機銀塩に対する量が表１の様になるように添加し、良く混合した乳剤層塗布液をそのままコーティングダイへ送液し、塗布した。
【０２０２】
≪乳剤面中間層塗布液の調製≫
ポリビニルアルコールＰＶＡ−２０５（クラレ（株）製）の１０質量％水溶液７７２ｇ、顔料−１分散物５．３ｇ、メチルメタクリレート／スチレン／ブチルアクリレート／ヒドロキシエチルメタクリレート／アクリル酸共重合体（共重合重量比６４／９／２０／５／２）ラテックス２７．５質量％液２２６ｇにエアロゾールＯＴ（アメリカンサイアナミド社製）の５質量％水溶液を２ｍｌ、フタル酸二アンモニウム塩の２０質量％水溶液を１０．５ｍｌ、総量８８０ｇになるように水を加え、ｐＨが７．５になるようにＮａＯＨで調整して中間層塗布液とし、１０ｍｌ／ｍ²になるようにコーティングダイへ送液した。
塗布液の粘度はＢ型粘度計４０℃（Ｎｏ．１ローター、６０ｒｐｍ）で６５[ｍＰａ・ｓ]であった。
【０２０３】
≪乳剤面保護層第１層塗布液の調製≫
イナートゼラチン６４ｇを水に溶解し、メチルメタクリレート／スチレン／ブチルアクリレート／ヒドロキシエチルメタクリレート／アクリル酸共重合体（共重合重量比６４／９／２０／５／２）ラテックス２７．５質量％液８０ｇ、フタル酸の１０質量％メタノール溶液を２３ｍｌ、４−メチルフタル酸の１０質量％水溶液２３ｍｌ、０．５ｍｏｌ／Ｌ濃度の硫酸を２８ｍｌ、エアロゾールＯＴ（アメリカンサイアナミド社製）の５質量％水溶液を５ｍｌ、フェノキシエタノール０．５ｇ、ベンゾイソチアゾリノン０．１ｇを加え、総量７５０ｇになるように水を加えて塗布液とし、４質量％のクロムみょうばん２６ｍｌを塗布直前にスタチックミキサーで混合したものを１８．６ｍｌ／ｍ²になるようにコーティングダイへ送液した。
塗布液の粘度はＢ型粘度計４０℃（Ｎｏ.１ローター、６０ｒｐｍ）で２０[ｍＰａ・ｓ]であった。
【０２０４】
≪乳剤面保護層第２層塗布液の調製≫
イナートゼラチン８０ｇを水に溶解し、メチルメタクリレート／スチレン／ブチルアクリレート／ヒドロキシエチルメタクリレート／アクリル酸共重合体（共重合重量比６４／９／２０／５／２）ラテックス２７．５質量％液１０２ｇ、フッ素系界面活性剤（Ｆ−１：Ｎ−パーフルオロオクチルスルフォニル−Ｎ−プロピルアラニンカリウム塩）の５質量％溶液を３．２ｍｌ、フッ素系界面活性剤（Ｆ−２：ポリエチレングリコールモノ(Ｎ−パーフルオロオクチルスルホニル−Ｎ−プロピル−２−アミノエチル)エーテル[エチレンオキシド平均重合度＝１５]）の２質量％水溶液を３２ｍｌ、エアロゾールＯＴ（アメリカンサイアナミド社製）の５質量％溶液を２３ｍｌ、ポリメチルメタクリレート微粒子（平均粒径０．７μｍ）４ｇ、ポリメチルメタクリレート微粒子（平均粒径４．５μｍ）２１ｇ、４−メチルフタル酸１．６ｇ、フタル酸４．８ｇ、０．５ｍｏｌ／Ｌ濃度の硫酸４４ｍｌ、ベンゾイソチアゾリノン１０ｍｌに総量６５０ｇとなるよう水を添加して、４質量％のクロムみょうばんと０．６７質量％のフタル酸を含有する水溶液４４５ｍｌを塗布直前にスタチックミキサーで混合したものを表面保護層塗布液とし、８．３ｍｌ／ｍ²になるようにコーティングダイへ送液した。
塗布液の粘度はＢ型粘度計４０℃（Ｎｏ.１ローター,６０ｒｐｍ）で１９[ｍＰａ・ｓ]であった。
【０２０５】
≪熱現像感光材料−１の作成≫
上記下塗り支持体のバック面側に、ハレーション防止層塗布液を固体微粒子染料の固形分塗布量が０．０４ｇ／ｍ²となるように、またバック面保護層塗布液をゼラチン塗布量が１．７ｇ／ｍ²となるように同時重層塗布し、乾燥し、バック層を作成した。
【０２０６】
バック面と反対の面に下塗り面から乳剤層、中間層、保護層第１層、保護層第２層の順番でスライドビード塗布方式にて同時重層塗布し、熱現像感光材料の試料を作成した。このとき、乳剤層と中間層は３５℃に、保護層第一層は３６℃に、保護層第一層は３７℃に温度調整した。
乳剤層の各化合物の塗布量（ｇ／ｍ²）は以下の通りである。
【０２０７】
ベヘン酸銀 ６．１９
顔料(C.I.Pigment Blue 60) ０．０３６
ポリハロゲン化合物−２ ０．０４
ポリハロゲン化合物−３ ０．１２
フタラジン化合物−１ ０．２１
ＳＢＲラテックス １１．１
還元剤錯体−３ １．５４
メルカプト化合物−１ ０．００２
ハロゲン化銀（Ａｇとして） 表１に記載の量
【０２０８】
塗布乾燥条件は以下のとおりである。
塗布はスピード１６０ｍ／ｍｉｎで行い、コーティングダイ先端と支持体との間隙を０．１０〜０．３０ｍｍとし、減圧室の圧力を大気圧に対して１９６〜８８２Ｐａ低く設定した。支持体は塗布前にイオン風にて除電した。
引き続くチリングゾーンにて、乾球温度１０〜２０℃の風にて塗布液を冷却した後、無接触型搬送して、つるまき式無接触型乾燥装置にて、乾球温度２３〜４５℃、湿球温度１５〜２１℃の乾燥風で乾燥させた。
乾燥後、２５℃で湿度４０〜６０％ＲＨで調湿した後、膜面を７０〜９０℃になるように加熱した。加熱後、膜面を２５℃まで冷却した。
【０２０９】
作製された熱現像感光材料のマット度はベック平滑度で感光性層面側が５５０秒、バック面が１３０秒であった。また、感光層面側の膜面のｐＨを測定したところ６．０であった。
【０２１０】
以下に本発明の実施例で用いた化合物の化学構造を示す。
【０２１１】
【化１１】

【０２１２】
【化１２】

【０２１３】
【化１３】

【０２１４】
【化１４】

【０２１５】
【化１５】

【０２１６】
得られた試料は半切サイズに切断し、２５℃５０％の環境下で以下の包装材料に包装し、２週間常温下で保管した後、以下の評価を行った。
（包装材料）
ＰＥＴ １０μｍ／ＰＥ １２μｍ／アルミ箔９μｍ／Ｎｙ １５μｍ／カーボン３％を含むポリエチレン５０μｍ
酸素透過率：０ｍｌ／ａｔｍ・ｍ²・２５℃・ｄａｙ、水分透過率：０ｇ／ａｔｍ・ｍ²・２５℃・ｄａｙ
【０２１７】
実施例２
実施例１と同様にして、ただしハロゲン化銀乳剤１の代わりにその粒子形成時の温度を変化させることによって表１記載の様に粒子サイズを変化させたハロゲン化銀乳剤２〜６を作製した。同様に、使用するヨウ化カリウムの一部を臭化カリウムに変更し、量を調節し添加するハロゲン組成を変更することによって表１記載の様なハロゲン組成の異なる乳剤７、８を作製した。
これらハロゲン化銀乳剤１〜８を使用して、実施例１と同様にただしハロゲン化銀の塗布量を変化させることによって表１に記載の様な熱現像感光材料２〜１４を作製した。
【０２１８】
（写真性能の評価）
試料は富士メディカルドライレーザーイメージャーＦＭ−ＤＰＬを改造し露光・現像処理を行った。
露光は、ＦＭ−ＤＰＬ搭載の最大６０ｍＷ（IIIＢ）出力の６６０ｎｍ半導体レーザーを１００μｍ＊１００μｍに絞って感材を照射した。レーザーの露光量を段階的に変化させて露光を行った。
現像は、ＦＭ−ＤＰＬの熱現像部を用いて、４枚のパネルヒーターの温度を１１２℃−１１９℃−１２１℃−１２１℃に設定して行った。現像時間は２４秒とした。現像進行性の評価においては、搬送速度を変化させることによって熱現像時間を変化させた。
露光・現像後に得られた画像の評価は、Macbeth濃度計により濃度測定を行い、露光量に対する濃度の特性曲線を作成した。
現像処理後サンプルにおいて、レーザーが露光されていない部分の濃度をＤｍｉｎとし、また最高露光量で露光した部分の濃度をＤｍａｘとした。またＤｍｉｎ＋１．０の濃度を得る露光量の逆数を感度とし、基準感材に対して表記した。
【０２１９】
熱現機の搬送速度を変化させることによって現像時間が１６秒となるように現像処理を行い特性曲線を作成した。２４秒現像のときと同様に、Ｄｍｉｎ＋１．０の濃度を得るために必要な露光量の逆数を感度とした。２４秒現像の時の感度と１６秒現像の時の感度から、以下の式によって算出される値を現像進行性として評価した。
【０２２０】
現像進行性＝Ｌｏｇ（２４秒感度／１６秒感度）
【０２２１】
値が大きい方が現像性が遅く処理時間の変化に対して安定でないことになる。より値が小さい方が好ましい。
【０２２２】
（プリントアウト性能の評価） 条件１
処理後のサンプルを３０℃７０％の環境下に設置し、１０００ルクスの照度の蛍光灯下で３日間放置した。処理前に対する被り部分の濃度の増加をプリントアウト性能とした。
【０２２３】
（プリントアウト性能の評価） 条件２
条件１と同様にして、ただし２５℃７０％の環境下３００ルクスの照度の蛍光灯下で１０日間放置をした。このときの被りの上昇をプリントアウト性能とした。
この様にして試料１〜１４を評価した結果を表１に示す。
【０２２４】
【表１】

【０２２５】
この結果から明らかなように、本発明の試料はプリントアウト性能に優れ、かつ現像進行性とＤｍａｘ性能に優れて好ましいことが分かる。本発明の高ヨウ化銀乳剤はそのサイズを９０ｎｍ以下とすることによってこの性能を達成できる。また、有機銀塩に対する高ヨウ化銀乳剤の添加モル数も少ない方がより好ましいことが分かる。
【０２２６】
実施例３
実施例１、２のようにハロゲン化銀を塗布の前に混合する方法に対して、有機銀塩をコンバージョンする方法でも本発明の効果は達成されることを示す。
【０２２７】
＜コンバージョン法による高ヨウ化銀乳剤を含有した感材の作製＞
実施例１と同様に、ただし≪乳剤層（感光性層）塗布液−１の調製≫において、ハロゲン化銀乳剤Ａを添加する代わりにＫＩ溶液を添加することによって脂肪酸銀のコンバージョンを行い、ハロゲン化銀１モル当たり、乳剤１と同量の増感色素Ａ、Ｂ及び５−メチル−２−メルカプトベンヅイミダゾールを添加した以外は同様にして熱現象感光材料を作製した。
添加するＫＩの量を変化させることによって試料１５、１６、１７を作成した。
この様にして作製した試料１５〜１７と、実施例２の試料２，４，８を実施例２と同様にして評価を行った。結果を表２に示す。
【０２２８】
【表２】

【０２２９】
この様にコンバージョン法によって作製した試料でも同様に本発明の現像促進の効果は得られる。ただしコンバージョン法ではその感度が低い。本発明の高ヨウ化銀乳剤は有機銀塩の存在しないところで作製することがより好ましい。
【０２３０】
実施例４
次に本発明の高ヨウ化銀乳剤はレーザー露光の様な高照度の露光に対して特に好ましいことを示す。
実施例２のＦＭ−ＤＰＬによる露光は照度を測定したところ最高出力部で４Ｗ／ｍｍ²であった。一方、光源としてキセノン光源を用い、光露光によってステップウェッジを介して露光を行った。照度を測定したところ３ｍＷ／ｍｍ²であった。露光時間を調節して必要な濃度が得られるように露光した。
実施例２の試料４、１２についてそれぞれ２つの条件で露光し感度をもとめた。感度はそれぞれのサンプルのレーザー露光での感度を１００として、Ｄｍｉｎ＋１．０の濃度を得るために必要な光量（＝照度×時間）の逆数で表した。結果を表３に示す。
【０２３１】
【表３】

【０２３２】
この例から分かる様に本発明の高ヨウ化銀乳剤を使用した感材は、レーザー露光の様な高照度露光に対して特に感度が優れていることが分かる。
【０２３３】
実施例５
本発明においては、ポリハロゲン化合物は必須である。その効果を示す。
実施例１と同様にしてただしハロゲン化銀乳剤１とハロゲン化銀乳剤８を用いて、また有機ポリハロゲン化銀化合物２、３の比率は同じまま表４に記載の様に添加量を変化させて試料２０〜２５を作製した。
得られたサンプルを実施例２に記載の方法でＤｍｉｎ、Ｄｍａｘ、プリントアウト条件１、条件２を調べた。結果を表４に示す。
【０２３４】
【表４】

【０２３５】
表４から明らかなように本発明の高ヨウ化銀乳剤の特徴はポリハロゲン化銀化合物が存在するところで顕著に現れる。また表４よりヨウ化銀含量の少ない比較例の感材のプリントアウト性能をポリハロゲン化合物の増量で改良しようと試みても、各種環境条件においてプリントアウトが良好な状況を作り出すことは難しいことが分かる。
本発明の高ヨウ化銀乳剤はこの様なプリントアウトの起こる環境（温湿度・光照度）が変化しても良好な結果が得られる。
【０２３６】
実施例６
レーザー光を高周波重畳によって縦マルチモードで発振させて実施例２と同様の実験を行った。実施例２と同様に好ましい結果が得られた。
【０２３７】
実施例７
実施例２の試料４と同様にして、ただし乳剤１の代わりに乳剤４と乳剤３を８：２で混合したものを用いて熱現像感光材料２６を作製した。実施例２と同様に評価を行った結果、好ましい結果が得られた。
【０２３８】
実施例８
実施例２の試料３と同様にして、ただし還元剤錯体の代わりに以下の化合物を使用することによって熱現像感光材料を作製した。
【０２３９】
≪還元剤−５分散物の調製≫
還元剤−５（２,２'−メチレンビス−(４−メチル−６−tert−ブチルフェノール)）１０Ｋｇと変性ポリビニルアルコール（クラレ（株）製、ポバールＭＰ２０３）の１０質量％水溶液２０Ｋｇに、水６Ｋｇを添加して、良く混合してスラリーとした。
このスラリーをダイアフラムポンプで送液し、平均直径０．５ｍｍのジルコニアビーズを充填した横型サンドミル（ＵＶＭ−２：アイメックス（株）製）にて３時間３０分分散したのち、ベンゾイソチアゾリノンナトリウム塩０．２ｇと水を加えて還元剤の濃度が２５質量％になるように調製し、還元剤−５分散物を得た。
こうして得た還元剤分散物に含まれる還元剤粒子はメジアン径０．３８μｍ、最大粒子径１．５μｍ以下であった。得られた還元剤分散物は孔径３．０μｍのポリプロピレン製フィルターにてろ過を行い、ゴミ等の異物を除去して収納した。
【０２４０】
≪水素結合性化合物−２分散物の調製≫
水素結合性化合物−２（トリ（４−ｔ−ブチルフェニル）ホスフィンオキシド）１０Ｋｇと変性ポリビニルアルコール（クラレ（株)製、ポバールＭＰ２０３）の１０質量％水溶液２０Ｋｇに、水１０Ｋｇを添加して、良く混合してスラリーとした。
このスラリーをダイアフラムポンプで送液し、平均直径０．５ｍｍのジルコニアビーズを充填した横型サンドミル（ＵＶＭ−２：アイメックス（株）製）にて３時間３０分分散したのち、ベンゾイソチアゾリノンナトリウム塩０．２ｇと水を加えて還元剤の濃度が２２質量％になるように調製し、水素結合性化合物−２分散物を得た。
こうして得た還元剤分散物に含まれる還元剤粒子はメジアン径０．３５μｍ、最大粒子径１．５μｍ以下であった。得られた水素結合性化合物分散物は孔径３．０μｍのポリプロピレン製フィルターにてろ過を行い、ゴミ等の異物を除去して収納した。
【０２４１】
≪熱現像感光材料２７の作成≫
実施例２の試料３と同様にして、ただし還元剤−３の代わりに還元剤−５と水素結合性化合物−２を用いることによって熱現像感光材料２７を作製した。乳剤層の各化合物の塗布量（ｇ／ｍ²）は以下の通りである。
【０２４２】
ベヘン酸銀 ６．１９
還元剤−５ ０．７６
水素結合性化合物２ ０．５９
顔料(C.I.Pigment Blue 60) ０．０３２
ポリハロゲン化合物−２ ０．０４
ポリハロゲン化合物−３ ０．１２
フタラジン化合物−１ ０．２１
ＳＢＲラテックス １１．１
メルカプト化合物−１ ０．００２
ハロゲン化銀（Ａｇとして） ０．１４５
【０２４３】
実施例２と同様に評価を行った結果好ましい化合物が得られた。
【０２４４】
実施例９
実施例８の還元剤−５の代わりに、還元剤−２の化合物を用いて同様に分散物を作成し熱現像感光材料２８を作製した。
熱現像機の搬送速度を変更して熱現像時間１４秒で現像処理を行った結果、好ましい感度・階調が得られた。
【０２４５】
実施例１０
本発明の感光材料１〜５、９、１３および１４を用いて写真性能の評価を行った。写真性能の評価は実施例２と同様にして、ただし４枚あるヒーターの設定温度を全て１０８℃に設定したこと以外は同様にして評価を行った。結果を表５に示す。
【０２４６】
【表５】

【０２４７】
表５から明らかなように本発明の高ヨウ化銀を用いた感光材料の現像進行性は、１０８℃のような低温現像では高臭化銀を用いた感光材料より良好である。表１（現像温度１１２〜１２１℃）から分かるように、現像温度を１１０℃以上とすると高臭化銀を用い感光材料に比べて顕著な現像抑制（現像進行性の悪化）が起こるが（試料１０〜１２と１３、１４とを参照）、しかし、本発明の感光材料（試料１〜５など）は、このような条件でも、好ましい現像進行性を得ることができ、高感度で現像処理安定性に優れている。
【０２４８】
【発明の効果】
本発明により、高感度で現像処理安定性に優れ、かつ処理後の光画像保存性に優れた熱現像感光材料を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photothermographic material. In particular, the present invention relates to a highly sensitive photosensitive material having improved image storage stability after development processing.
[0002]
[Prior art]
In recent years, in the medical field, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental protection and space saving. Therefore, photosensitive heat for medical diagnosis and photographic technology that can be efficiently exposed by a laser image setter or laser imager and can form a clear black image having high resolution and sharpness. There is a need for techniques relating to developed photographic materials. These photosensitive photothermographic materials can eliminate the use of solution processing chemicals and supply customers with a simpler heat development processing system that does not damage the environment.
[0003]
Although there is a similar requirement in the field of general image forming materials, medical images are required to have high image quality with excellent sharpness and graininess because they are required to be finely drawn, and are cooled from the viewpoint of ease of diagnosis. There is a feature that a black tone image is preferred. At present, various hard copy systems using pigments and dyes such as inkjet printers and electrophotography are distributed as general image forming systems. However, there is no satisfactory output system for medical images.
[0004]
On the other hand, thermal imaging systems using organic silver salts are disclosed in, for example, the specifications of U.S. Pat. Nos. 3,152,904 and 3,457,075 and B.I. "Thermally Processed Silver Systems" by Shely (Imaging Processes and Materials Neblette 8th Edition, Sturge, V. Walworth (Walworth, A. Shepp, edited, page 2, 1996).
In particular, the photothermographic material generally contains a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), and a color tone that controls the color tone of silver if necessary. And a photosensitive layer dispersed in a binder matrix. The photothermographic material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure, and is blackened by an oxidation-reduction reaction between silver halide or a reducible silver salt (functioning as an oxidizing agent) and a reducing agent. Form a silver image. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, a black silver image is formed in the exposure area. Such a photothermographic material is disclosed in many documents including US Pat. No. 2910377 and Japanese Patent Publication No. 43-4924, and Fuji Medical Dry Imager FM- as a medical image forming system using the photothermographic material. DPL was released.
[0005]
In such an image forming system using an organic silver salt, since there is no fixing step, image storage stability after development processing, in particular, deterioration of printout when exposed to light has been a serious problem. US Pat. No. 6,143,488, EP0922995 discloses a method using AgI formed by converting an organic silver salt as a means for improving the printout. However, the method of converting an organic silver salt as disclosed herein with iodine cannot obtain sufficient sensitivity, and it is difficult to construct an actual system.
Other sensitive materials using AgI are described in WO97-48014, WO48015, US-6165705, JP-A-8-297345, Japanese Patent No. 2785129, etc. It was not resistant to practical use as a laser exposure sensitive material.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a photothermographic material having high sensitivity, excellent development processing stability, and excellent optical image storage stability after processing.
[0007]
[Means for Solving the Problems]
As a result of diligent studies to solve the above-mentioned problems, the present inventor has produced a preferable photothermographic material exhibiting the desired effect by using an organic polyhalogen compound and a specific photosensitive silver halide. As a result, the present invention has been solved.
That is, the present invention is as follows.
[0008]
(1) At least one selected from photosensitive silver halide, non-photosensitive organic silver salt having a behenic acid content of 50 mol% to 100%, a hindered phenol reducing agent, and a bisphenol reducing agent on the support. In a photothermographic material of the type that contains a thermal developer and a binder and is not heat-treated immediately before use, the photosensitive material comprisesIt is represented by the following general formula (H)An organic polyhalogen compound is contained, and the photosensitive silver halide contains a silver halide having a silver iodide content of 40 mol% to 100 mol% and an average grain size of 5 nm to 90 nm. A photothermographic material.
However, the photothermographic material does not contain a combination of a component that oxidizes free silver and a component that photooxidizes a reduced product of the component.
  General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In the general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, and Y represents —SO. ₂ -, N represents 1, Z ₁ And Z ₂ Represents a halogen atom, and X represents a hydrogen atom or an electron-withdrawing group.
[0009]
(2The silver halide content of the silver halide is 70 mol% or more and 100 mol% or less,(1)The photothermographic material according to the description.
(3The silver halide content of the silver halide is 90 mol% or more and 100 mol% or less (1)Or (2)The photothermographic material described in 1.
[0010]
(4) (1) to (31) The photothermographic material, wherein the silver halide has an average grain size of 5 nm to 70 nm.
(5) (1) to (42) the photothermographic material, wherein the silver halide is formed in the absence of a non-photosensitive organic silver salt.
[0011]
(6) (1) to (52) the photothermographic material, wherein the silver halide coating amount is 12 mol% or less based on 1 mol of the non-photosensitive organic silver salt.
(7) Said (6The photothermographic material is characterized in that the silver halide coating amount is 9 mol% or less with respect to 1 mol of the non-photosensitive organic silver salt.
(8) Said (6), Wherein the silver halide coating amount is 0.5 mol% or more and 7 mol% or less with respect to 1 mol of the non-photosensitive organic silver salt.
(9) Said (6) ~ (82) the photothermographic material, wherein the photothermographic material is thermally developed at a development temperature of 110 ° C. or higher and 130 ° C. or lower.
[0012]
(10(1) to (1) above, wherein the silver halide is spectrally sensitized so as to have a spectral sensitivity peak at a wavelength of 600 nm to 900 nm.9) A photothermographic material.
(11) (1) to (10An image forming method comprising exposing and recording the photothermographic material according to claim 1 with a semiconductor laser.
(12) Said (11), The laser exposure illuminance is 0.1 W / mm²An image forming method as described above.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
[0014]
(Description of silver halide)
It is important that the photosensitive silver halide used in the present invention is a silver halide having a high silver iodide content of 40 mol% or more and 100 mol% or less. The remaining 60 mol% is not particularly limited and can be selected from silver chloride and silver bromide, but silver bromide is particularly preferred.
By using such a high silver iodide emulsion, it is possible to design a preferable photothermographic material in which the image storability after development processing, in particular, the increase in fog due to light irradiation is extremely small.
A more preferable silver iodide content is 70 mol% or more and 100 mol% or less, and further preferably 80 mol% or more and 100 mol% or less. In particular, 90 mol% or more and 100 mol% or less is preferable from the viewpoint of optical image storage stability after processing.
[0015]
The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can be preferably used. A preferable structure is a 2- to 5-fold structure, and more preferably 2- to 5-fold core / shell particles can be used. A core high silver iodide structure or a shell high silver iodide structure can also be preferably used. A technique for localizing silver bromide on the surface of the grains can also be preferably used.
[0016]
The average grain size of the high silver iodide emulsion used in the present invention needs to be 5 nm or more and 90 nm or less. Larger silver halide sizes increase the amount of silver halide coating required to achieve the required maximum density.
The inventor of the present invention preferably uses a silver iodide emulsion preferably used in the present invention when the coating amount is large, the development is remarkably suppressed and the sensitivity is lowered and the density stability with respect to the development time is deteriorated. Then, it was found that the maximum density could not be obtained in a predetermined development time. On the other hand, it has been found that if the coating amount is limited, it has sufficient developability while being silver iodide. Thus, in order to achieve a sufficient maximum optical density with silver iodide, the size of the silver halide grains needs to be sufficiently small.
[0017]
The average grain size of silver halide is preferably 5 nm to 70 nm, more preferably 5 nm to 55 nm. Especially preferably, it is 10 nm or more and 45 nm or less.
The average grain size here means the average of the diameters when converted to a sphere having the same volume as the volume of the silver halide grains.
[0018]
The coating amount of such silver halide grains is preferably 0.5 mol% or more and 15 mol% or less, more preferably 0.5 mol% or more and 12 mol% or less with respect to 1 mol of organic acid silver described later. Further, it is more preferably 0.5 mol% or more and 9 mol% or less, and further preferably 0.5 mol% or more and 7 mol% or less. It is particularly preferable to set the coating amount of silver halide to a small amount such as 1 mol% or more and 7 mol% or less, and further 0.5 mol% or more and 5 mol% or less.
In order to suppress the remarkable development suppression by the high silver iodide emulsion found by the present inventor, it is extremely important to reduce the coating amount of silver halide in this way. In order to obtain a sufficient maximum optical density (Dmax) even if the amount of silver halide applied is small, it is important that the silver halide grain size is sufficiently small.
[0019]
Methods for forming photosensitive silver halide are well known in the art, for example, the methods described in Research Disclosure June 1978, No. 17029, and U.S. Pat.No. 3,700,458 can be used, Specifically, a method is used in which a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound to gelatin or another polymer solution, and then mixed with an organic silver salt. In addition, the method described in paragraph Nos. 0217 to 0224 of JP-A No. 11-119374, and the methods described in Japanese Patent Application Nos. 11-98708 and 2000-42336 are also preferable.
[0020]
Examples of the shape of silver halide grains include cubes, octahedrons, tabular grains, spherical grains, rod-shaped grains, and potato-shaped grains. The high silver iodide emulsion of the present invention has a complicated form. As a preferred form, for example, bonded particles as shown in P164-Fig1 of R.L.JENKINS et al. J of Phot. Sci. Vol28 (1980) are preferably used. Tabular grains as shown in Fig. 1 are also preferably used. Grains with rounded corners of silver halide grains can also be preferably used.
[0021]
The surface index (Miller index) of the outer surface of the photosensitive silver halide grain is not particularly limited, but the proportion of the [100] surface that has high spectral sensitization efficiency when adsorbed by the spectral sensitizing dye is high. preferable. The ratio is preferably 50% or more, more preferably 65% or more, and still more preferably 80% or more.
The ratio of the Miller index [100] plane is calculated by T. Tani; J. Imaging Sci., 29, 165 (1985) using the adsorption dependence of [111] plane and [100] plane in adsorption of sensitizing dye. It can be determined by the method described.
[0022]
In the present invention, silver halide grains in which a hexacyano metal complex is present on the outermost surface of the grains are preferred. As hexacyano metal complexes, [Fe (CN)₆]^Four-, [Fe (CN)₆]^3-, [Ru (CN)₆]^Four-, [Os (CN)₆]^Four-, [Co (CN)₆]^3-, [Rh (CN)₆]^3-, [Ir (CN)₆]^3-, [Cr (CN)₆]^3-, [Re (CN)₆]^3-Etc. In the present invention, a hexacyano Fe complex is preferred.
[0023]
The hexacyano metal complex is present in the form of ions in aqueous solution, so the counter cation is not important, but it is easy to mix with water and is suitable for precipitation of silver halide emulsions. Sodium ion, potassium ion, rubidium It is preferable to use alkali metal ions such as ions, cesium ions, and lithium ions, ammonium ions, and alkylammonium ions (for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetra (n-butyl) ammonium ion).
[0024]
In addition to water, the hexacyano metal complex is miscible with a mixed solvent or gelatin with an appropriate organic solvent miscible with water (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.). Can be added.
[0025]
The amount of hexacyano metal complex added is 1 × 10 5 per mole of silver.^-Five1 x 10 moles or more^-2Or less, more preferably 1 × 10^-Four1 x 10 moles or more^-3It is below the mole.
[0026]
In order for the hexacyano metal complex to be present on the outermost surface of the silver halide grain, the chalcogen sensitization of sulfur sensitization, selenium sensitization and tellurium sensitization is completed after the addition of the aqueous silver nitrate solution used for grain formation. It is added directly before the completion of the preparation step before the chemical sensitization step for performing noble metal sensitization such as sensitization and gold sensitization, during the washing step, during the dispersion step, or before the chemical sensitization step. In order to prevent the silver halide fine grains from growing, it is preferable to add the hexacyano metal complex immediately after the grain formation, and it is preferable to add it before the completion of the preparation step.
[0027]
The addition of the hexacyano metal complex may be started after adding 96% by mass of the total amount of silver nitrate to be added to form grains, more preferably starting after adding 98% by mass, The addition of 99% by mass is particularly preferable.
[0028]
When these hexacyanometal complexes are added after the addition of the aqueous silver nitrate solution just before the completion of grain formation, they can be adsorbed on the outermost surface of the silver halide grains, and most of them form slightly soluble salts with silver ions on the grain surface. To do.
Since this silver salt of hexacyanoiron (II) is a less soluble salt than AgI, it is possible to prevent re-dissolution by fine particles and to produce silver halide fine particles having a small particle size. .
[0029]
The photosensitive silver halide grain of the present invention can contain a metal or metal complex of Group 8 to Group 10 of the Periodic Table (showing Groups 1 to 18). As the central metal of the group 8 to group 10 metal or metal complex of the periodic table, rhodium, ruthenium and iridium are preferable. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination.
The preferred content is 1 x 10 per mole of silver.^-9From mole to 1 × 10^-3A molar range is preferred. These heavy metals and metal complexes and methods for adding them are described in JP-A-7-225449, JP-A-11-65021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240.
[0030]
Further, metal atoms that can be contained in the silver halide grains used in the present invention (for example, [Fe (CN)₆]^Four-), Desalting methods and chemical sensitization methods for silver halide emulsions, paragraph numbers 0046 to 0050 of JP-A-11-84574, paragraph numbers 0025 to 0031 of JP-A-11-65021, paragraph number 0242 of JP-A-11-119374 ~ 0250.
[0031]
Various gelatins can be used as the gelatin contained in the photosensitive silver halide emulsion used in the present invention. In order to satisfactorily maintain the dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution, it is preferable to use low molecular weight gelatin having a molecular weight of 500 to 60000. These low molecular weight gelatins may be used at the time of particle formation or dispersion after desalting, but are preferably used at the time of dispersion after desalting.
[0032]
As a sensitizing dye that can be applied to the present invention, it can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and has a spectral sensitivity suitable for the spectral characteristics of the exposure light source. The dye can be advantageously selected.
The light-sensitive material of the present invention is particularly preferably spectrally sensitized so as to have a spectral sensitivity peak at 600 nm or more and 900 nm or less.
[0033]
As for the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A-11-65021, compounds represented by general formula (II) of JP-A-10-186572, and general formula (I of JP-A-11-119374) And dyes described in paragraph No. 0106, U.S. Pat. Nos. 5,510,236 and 3,871,887, Example 5, dyes disclosed in JP-A-2-96131 and JP-A-59-48753, European Patent Publication No. 074364A1, page 19, line 38 to page 20, line 35, Japanese Patent Application No. 2000-86865, Japanese Patent Application No. 2000-102560, Japanese Patent Application No. 2000-205399, and the like. These sensitizing dyes may be used alone or in combination of two or more.
In the present invention, the time when the sensitizing dye is added to the silver halide emulsion is preferably the time from the desalting step to the coating, and more preferably the time from the desalting to the start of chemical ripening.
[0034]
The addition amount of the sensitizing dye in the present invention can be set to a desired amount in accordance with the sensitivity and fogging performance.^-6~ 1 mol is preferred, more preferably 10^-Four-10^-1Is a mole.
[0035]
In the present invention, a supersensitizer can be used to improve spectral sensitization efficiency. Supersensitizers used in the present invention include European Patent Publication No. 587,338, U.S. Pat.Nos. 3,877,943, 4,873,184, JP-A-5-341432, 11-109547, 10-111543, etc. And the compounds described.
[0036]
The photosensitive silver halide grain in the present invention is preferably chemically sensitized by sulfur sensitizing method, selenium sensitizing method or tellurium sensitizing method. As the compound preferably used in the sulfur sensitization method, selenium sensitization method and tellurium sensitization method, known compounds, for example, compounds described in JP-A-7-128768 and the like can be used. In the present invention, tellurium sensitization is particularly preferred. The compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, and the general formulas (II), (III), (IV) described in JP-A-5-313284 The compound shown by is more preferable.
[0037]
In the present invention, chemical sensitization can be performed at any time after particle formation and before coating. After desalting, (1) before spectral sensitization, (2) simultaneously with spectral sensitization, (3) spectral After sensitization, there may be (4) immediately before application. In particular, it is preferably performed after spectral sensitization.
[0038]
The amount of sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains used, chemical ripening conditions, etc., but is 10 per mol of silver halide.^-8-10^-2Moles, preferably 10^-7-10^-3Use moles. The conditions for chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is about 40 to 95 ° C.
A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method described in European Patent Publication No. 293,917.
[0039]
The light-sensitive silver halide emulsion in the light-sensitive material used in the present invention may be one kind or two or more kinds (for example, those having different average grain sizes, different halogen compositions, different crystal habits, chemical increase). Those with different feeling conditions) may be used in combination. The gradation can be adjusted by using a plurality of types of photosensitive silver halides having different sensitivities.
As technologies related to these, JP-A-57-119341, 53-106125, 47-3929, 48-55730, 46-5187, 50-73627, 57-150841, etc. Can be mentioned. The sensitivity difference is preferably 0.2 log E or more for each emulsion.
[0040]
The high silver iodide of the present invention is particularly preferably formed in the absence of a non-photosensitive organic silver salt. In some cases, sufficient sensitivity cannot be achieved by the method of forming silver halide by adding a halogenating agent to the organic silver salt.
Thus, in the absence of the non-photosensitive organic silver salt, the mixing method and mixing conditions of the silver halide and the non-photosensitive organic silver salt are as follows. Mixing with a stirrer, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc., or mixing photosensitive silver halide prepared at any timing during the preparation of organic silver salt Examples of the preparation method are listed. In any method, the effects of the present invention can be preferably obtained.
[0041]
The preferred addition timing of the silver halide of the present invention to the image forming layer coating solution is from 180 minutes before coating to immediately before, preferably from 60 minutes to 10 seconds before coating. There is no particular limitation as long as the effect is sufficiently exhibited.
Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid delivered to the coater is the desired time, and by N. Harnby, MFEdwards, AWNienow, Takahashi There is a method of using a static mixer or the like described in Chapter 8 of “Liquid mixing technology” (published by Nikkan Kogyo Shimbun, 1989).
[0042]
(Description of organic silver salt)
The organic silver salt that can be used in the present invention is relatively stable to light, but at 80 ° C. or in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a thermal developer. It is a silver salt that forms a silver image when heated further. The organic silver salt may be any organic material containing a source capable of reducing silver ions.
Regarding such non-photosensitive organic silver salt, paragraph numbers 0048 to 0049 of JP-A No. 10-62899, page 18 line 24 to page 19 line 37 of European Patent Publication No. 080864A1, European Patent Publication No. 0962812A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, and the like. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids (having 10 to 30, preferably 15 to 28 carbon atoms) are preferred.
[0043]
  Preferable examples of the organic silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and a mixture thereof. In the present inventionAn organic acid silver having a silver behenate content of 50 mol% to 100 mol% is used.In particular, the silver behenate content is preferably 75 mol% or more and 98 mol% or less.
[0044]
The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be a needle shape, a rod shape, a flat plate shape, or a flake shape.
In the present invention, scaly organic silver salts are preferred. In the present specification, the scaly organic silver salt is defined as follows. The organic silver salt is observed with an electron microscope, the shape of the organic silver salt particle is approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped are defined as a, b, and c from the shortest side (even though c is the same as b) Good)), and calculate with the shorter numbers a and b, and find x as follows.
x = b / a
[0045]
In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, particles satisfying the relationship of x (average) ≧ 1.5 are defined as flakes. Preferably, 30 ≧ x (average) ≧ 1.5, more preferably 20 ≧ x (average) ≧ 2.0. Incidentally, the needle shape is 1 ≦ x (average) <1.5.
[0046]
In the flake shaped particle, a can be regarded as a thickness of a tabular particle having a main plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.23 μm, more preferably 0.1 μm or more and 0.20 μm or less. The average of c / b is preferably 1 or more and 6 or less, more preferably 1.05 or more and 4 or less, further preferably 1.1 or more and 3 or less, and particularly preferably 1.1 or more and 2 or less.
[0047]
The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion is preferably 100% or less, more preferably 80% or less, and even more preferably 50% of the value obtained by dividing the standard deviation of the lengths of the short and long axes by the short and long axes. Indicates the following. The method for measuring the shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion.
As another method for measuring monodispersity, there is a method for obtaining the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (variation coefficient) of the value divided by the volume weighted average diameter is preferably 100% or less, more Preferably it is 80% or less, More preferably, it is 50% or less. As a measuring method, for example, it is obtained from the particle size (volume weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to the temporal change of the fluctuation of the scattered light. Can do.
[0048]
Known methods and the like can be applied to the production and dispersion method of the organic silver salt used in the present invention. For example, Japanese Patent Application Laid-Open No. 10-62899, European Patent Publication No. 0803683A1, European Patent Publication No. 0962812A1, Japanese Patent Application Laid-Open No. 11-349591, Japanese Patent Application Laid-Open No. 2000-7683, Japanese Patent Application No. 2000-72711, Japanese Patent Application No. 11-348228- No. 30, No. 11-203413, No. 2000-90093, No. 2000-195621, No. 2000-191226, No. 2000-213813, No. 2000-214155, No. 2000-191226, etc. be able to.
[0049]
In the present invention, a photosensitive material can be produced by mixing an organic silver salt aqueous dispersion and a photosensitive silver halide aqueous dispersion. When mixing, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver halide aqueous dispersions is a method preferably used for adjusting photographic characteristics.
[0050]
The organic silver salt of the present invention can be used in a desired amount, but the amount of silver is 0.1 to 5 g / m.²Is more preferable, and more preferably 1 to 3 g / m.²It is. Particularly preferably 1.2 to 2.5 g / m²It is.
[0051]
(Description of thermal developer)
The photothermographic material of the present invention contains a heat developer. Examples of the thermal developer include a reducing agent for organic silver salt.
The reducing agent for the organic silver salt may be any substance (preferably an organic substance) that reduces silver ions to metallic silver. Such a reducing agent is described in paragraph Nos. 0043 to 0045 of JP-A No. 11-65021 and page 7 line 34 to page 18 line 12 of European Patent Publication No. 0080374A1.
[0052]
In the present invention, the reducing agent is preferably a hindered phenol reducing agent or a bisphenol reducing agent, and more preferably a compound represented by the following general formula (R).
[0053]
[Chemical 1]

[0054]
(In the general formula (R), R¹¹And R¹¹Each independently represents an alkyl group having 1 to 20 carbon atoms. R¹²And R¹²Each independently represents a hydrogen atom or a substituent that can be substituted on the benzene ring. L is a -S- group or -CHR.¹³-Represents a group. R¹³Represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. X¹And X¹Each independently represents a hydrogen atom or a group capable of substituting for a benzene ring. )
[0055]
The general formula (R) will be described in detail.
R¹¹And R¹¹Each independently represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and the substituent of the alkyl group is not particularly limited, but is preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group. Group, alkylthio group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, acyl group, carbamoyl group, ester group, halogen atom and the like.
[0056]
R¹²And R¹²'Are each independently a hydrogen atom or a substituent capable of substituting for a benzene ring;¹And X¹Each 'also independently represents a hydrogen atom or a group that can be substituted on the benzene ring. Preferred examples of each group that can be substituted on the benzene ring include an alkyl group, an aryl group, a halogen atom, an alkoxy group, and an acylamino group.
[0057]
L is a -S- group or -CHR.¹³-Represents a group. R¹³Represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a substituent.
R¹³Specific examples of the unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a heptyl group, an undecyl group, an isopropyl group, a 1-ethylpentyl group, and a 2,4,4-trimethylpentyl group. .
Examples of substituents for alkyl groups are R¹¹In the same manner as the above substituent, a halogen atom, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group, an oxycarbonyl group, a carbamoyl group, a sulfamoyl group and the like can be mentioned.
[0058]
R¹¹And R¹¹'Is preferably a secondary or tertiary alkyl group having 3 to 15 carbon atoms, specifically, isopropyl group, isobutyl group, t-butyl group, t-amyl group, t-octyl group, cyclohexyl group, cyclopentyl. Group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like.
R¹¹And R¹¹'Is more preferably a tertiary alkyl group having 4 to 12 carbon atoms, among which a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferable, and a t-butyl group is most preferable.
[0059]
R¹²And R¹²'Is preferably an alkyl group having 1 to 20 carbon atoms, specifically, methyl group, ethyl group, propyl group, butyl group, isopropyl group, t-butyl group, t-amyl group, cyclohexyl group, 1-methyl group. Examples include cyclohexyl group, benzyl group, methoxymethyl group, methoxyethyl group and the like. More preferred are methyl group, ethyl group, propyl group, isopropyl group and t-butyl group.
X¹And X¹'Is preferably a hydrogen atom, a halogen atom or an alkyl group, more preferably a hydrogen atom.
[0060]
L is preferably -CHR¹³-Group.
R¹³Is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and the alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4,4-trimethylpentyl group. R¹³Particularly preferred is a hydrogen atom, a methyl group, a propyl group or an isopropyl group.
[0061]
R¹³R is a hydrogen atom, R¹²And R¹²'Is preferably an alkyl group having 2 to 5 carbon atoms, more preferably an ethyl group or a propyl group, and most preferably an ethyl group.
R¹³Is a primary or secondary alkyl group having 1 to 8 carbon atoms, R¹²And R¹²'Is preferably a methyl group. R¹³The primary or secondary alkyl group having 1 to 8 carbon atoms is preferably a methyl group, an ethyl group, a propyl group or an isopropyl group, more preferably a methyl group, an ethyl group or a propyl group.
R¹¹, R¹¹', R¹²And R¹²When both ′ are methyl groups, R¹³Is preferably a secondary alkyl group. In this case R¹³As the secondary alkyl group, isopropyl group, isobutyl group, and 1-ethylpentyl group are preferable, and isopropyl group is more preferable.
[0062]
Although the specific example of the reducing agent of this invention including the compound represented by general formula (R) of this invention below is shown, this invention is not limited to these.
[0063]
[Chemical formula 2]

[0064]
[Chemical 3]

[0065]
[Formula 4]

[0066]
Particularly preferred are compounds as shown in (I-1) to (I-20).
[0067]
In the present invention, the reducing agent is added in an amount of 0.01 to 5.0 g / m.²Is preferably 0.1 to 3.0 g / m.²More preferably, it is contained in an amount of 5 to 50 mol%, more preferably 10 to 40 mol%, based on 1 mol of silver on the surface having the image forming layer. The reducing agent is preferably contained in the image forming layer.
[0068]
The reducing agent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.
Well-known emulsifying dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. The method of producing is mentioned.
[0069]
In addition, as a solid fine particle dispersion method, a reducing agent powder is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to create a solid dispersion. A method is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. The aqueous dispersion can contain a preservative (eg, benzoisothiazolinone sodium salt).
[0070]
(Description of development accelerator)
In the photothermographic material of the present invention, a phenol derivative represented by the following general formula (A) is preferably used as a development accelerator.
[0071]
[Chemical formula 5]

[0072]
In formula (A), R¹, R², R^Three, X¹¹And X¹²Each independently represents a hydrogen atom, a halogen atom, or a substituent bonded to the benzene ring by a carbon atom, oxygen atom, nitrogen atom, sulfur atom or phosphorus atom. However, X¹¹, X¹²At least one of -NR^FourR^FiveIt is group represented by these.
R^Four, R^FiveEach independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, or —C (═O) —R, —C (═O) —C (═O) —R, —SO₂-R, -SO-R, -P (= O) (R)₂Or it is group represented by -C (= NR ')-R.
R and R ′ are each independently a group selected from a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, an amino group, an alkoxy group, and an aryloxy group. These substituents may be bonded to each other to form a ring.
[0073]
(Description of hydrogen bonding compound)
When the reducing agent in the present invention has an aromatic hydroxyl group (—OH), particularly in the case of the aforementioned bisphenols, a non-reducing compound having a group capable of forming a hydrogen bond with these groups It is preferable to use together.
Examples of the group that forms a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Can be mentioned.
[0074]
Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (however, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a urethane group. (However, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a ureido group (however, it has no> N—H group,> N-Ra (Ra is a substituent other than H).)
[0075]
In the present invention, a particularly preferred hydrogen bonding compound is a compound represented by the following general formula (D).
[0076]
[Chemical 6]

[0077]
In general formula (D), R^{twenty one}Or R^{twenty three}Each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group, and these groups may be unsubstituted or may have a substituent.
[0078]
R^{twenty one}Or R^{twenty three}In the case where has a substituent, the substituent is a halogen atom, alkyl group, aryl group, alkoxy group, amino group, acyl group, acylamino group, alkylthio group, arylthio group, sulfonamido group, acyloxy group, oxycarbonyl group, carbamoyl Group, sulfamoyl group, sulfonyl group, phosphoryl group and the like. Preferred as substituents are alkyl groups or aryl groups such as methyl group, ethyl group, isopropyl group, t-butyl group, t-octyl group, phenyl group, 4-alkoxyphenyl group, 4-acyloxyphenyl group and the like can be mentioned.
[0079]
R^{twenty one}Or R^{twenty three}Specific examples of the alkyl group include methyl group, ethyl group, butyl group, octyl group, dodecyl group, isopropyl group, t-butyl group, t-amyl group, t-octyl group, cyclohexyl group, and 1-methylcyclohexyl group. Benzyl group, phenethyl group, 2-phenoxypropyl group, and the like.
Examples of the aryl group include a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-t-butylphenyl group, a 4-t-octylphenyl group, a 4-anisidyl group, and a 3,5-dichlorophenyl group.
[0080]
Alkoxy groups include methoxy, ethoxy, butoxy, octyloxy, 2-ethylhexyloxy, 3,5,5-trimethylhexyloxy, dodecyloxy, cyclohexyloxy, 4-methylcyclohexyloxy, benzyl An oxy group etc. are mentioned.
Examples of the aryloxy group include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, and a biphenyloxy group.
Examples of the amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, and an N-methyl-N-phenylamino group. .
[0081]
R^{twenty one}Or R^{twenty three}Are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In terms of the effect of the present invention, R^{twenty one}Or R^{twenty three}Of these, at least one is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. In addition, R can be obtained at low cost.^{twenty one}Or R^{twenty three}Are preferably the same group.
[0082]
Specific examples of the hydrogen bonding compound including the compound of the general formula (D) in the present invention are shown below, but the present invention is not limited thereto.
[0083]
[Chemical 7]

[0084]
[Chemical 8]

[0085]
Specific examples of the hydrogen bonding compound include those described in Japanese Patent Application Nos. 2000-192191 and 2000-194811 in addition to those described above.
The compound of the general formula (D) that can be used in the present invention can be used in a light-sensitive material after being contained in a coating solution in the form of a solution, an emulsified dispersion, or a solid dispersed fine particle dispersion, in the same manner as the reducing agent. it can. The compound of the present invention forms a hydrogen-bonding complex with a compound having a phenolic hydroxyl group or an amino group in a solution state. Depending on the combination of the reducing agent and the compound of the general formula (D), It can be isolated.
[0086]
The use of the crystal powder isolated in this way as a solid dispersed fine particle dispersion is particularly preferable for obtaining stable performance. Further, a method in which a reducing agent and a compound of the general formula (D) are mixed as a powder and complexed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can be preferably used.
[0087]
The compound of the general formula (D) that can be used in the present invention is preferably used in the range of 1 to 200 mol%, more preferably in the range of 10 to 150 mol%, more preferably relative to the reducing agent. Is in the range of 30 to 100 mol%.
[0088]
(Description of binder)
The binder of the organic silver salt-containing layer of the present invention may be any polymer, suitable binders are transparent or translucent and generally colorless, natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, other films Forming media such as gelatins, rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) , Poly (methyl methacrylic acid) s, poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, Poly (vinyl acetal) s (eg, poly (vinyl acetal) Marl) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s , Poly (olefin) s, cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.
[0089]
In the present invention, the glass transition temperature of the binder that can be used in combination with the layer containing the organic silver salt is preferably 0 ° C. or higher and 80 ° C. or lower (hereinafter sometimes referred to as a high Tg binder), and is preferably 10 ° C. or higher and 70 ° C. or lower. It is more preferable that the temperature is 15 ° C. or higher and 60 ° C. or lower.
[0090]
In this specification, Tg was calculated by the following formula.
1 / Tg = Σ (Xi / Tgi)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. Xi is the weight fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, Σ is the sum from i = 1 to n.
The homopolymer glass transition temperature (Tgi) of each monomer is the value of Polymer Handbook (3rd Edition) (J. Brandrup, E.H. Immergut (Wiley-Interscience, 1989)).
[0091]
The polymer used as the binder may be used alone or in combination of two or more as required. Further, a glass transition temperature of 20 ° C. or higher and a glass transition temperature of less than 20 ° C. may be used in combination. When two or more kinds of polymers having different Tg are blended, the weight average Tg is preferably within the above range.
[0092]
In the present invention, when the organic silver salt-containing layer is formed using a coating solution in which 30% by mass or more of the solvent is water and dried, the binder of the organic silver salt-containing layer is further added to an aqueous solvent ( When it is soluble or dispersible in an aqueous solvent), the performance is improved particularly when it is made of a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. The most preferable form is one prepared so that the ionic conductivity is 2.5 mS / cm or less, and as such a preparation method, there is a method of performing purification treatment using a separation functional membrane after polymer synthesis.
[0093]
The aqueous solvent in which the polymer is soluble or dispersible here is a mixture of water or water and 70% by mass or less of a water-miscible organic solvent.
Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol, cellosolvs such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, ethyl acetate and dimethylformamide.
[0094]
In the case of a system in which the polymer is not dissolved thermodynamically and exists in a so-called dispersed state, the term aqueous solvent is used here.
[0095]
The “equilibrium moisture content at 25 ° C. and 60% RH” is the following using the weight W1 of the polymer in the humidity-controlled equilibrium under the atmosphere of 25 ° C. and 60% RH and the weight W0 of the polymer in the dry state at 25 ° C. It can be expressed as
Equilibrium moisture content at 25 ° C. and 60% RH = [(W1-W0) / W0] × 100 (mass%)
[0096]
For the definition and measurement method of the moisture content, for example, Polymer Engineering Course 14, Polymer Materials Testing Method (Edited by Polymer Society, Jinshokan) can be referred to.
[0097]
The equilibrium moisture content at 25 ° C. and 60% RH of the binder polymer of the present invention is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and further preferably 0.02% by mass. % To 1% by mass is desirable.
[0098]
In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state include latex in which fine particles of water-insoluble hydrophobic polymer are dispersed and polymer molecules dispersed in a molecular state or forming micelles, and all are preferable. The average particle size of the dispersed particles is preferably 1 to 50000 nm, more preferably about 5 to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.
[0099]
In the present invention, preferred examples of the polymer dispersible in the aqueous solvent include acrylic polymers, poly (esters), rubbers (for example, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (acetic acid). Hydrophobic polymers such as vinyl), poly (vinylidene chloride) and poly (olefin) can be preferably used.
These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer.
These polymers have a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 200,000. When the molecular weight is too small, the mechanical strength of the emulsion layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable.
[0100]
<Latex synthesis method>
The high Tg polymer fine dispersion which can be preferably used in the present invention can be obtained by a usual polymerization reaction such as emulsion polymerization, dispersion polymerization, suspension polymerization and the like. However, since most of the coating of the photographic light-sensitive material uses water as a medium and water-insoluble substances such as the copolymer are handled in the form of an aqueous dispersion, emulsion polymerization or dispersion polymerization is preferable from the viewpoint of coating solution preparation, It is particularly preferable to synthesize by emulsion polymerization.
When the latex is used, the fine particles usually have a particle size of 300 nm or less. Among these, the particle size is preferably 200 nm or less, and particularly preferably 150 nm or less.
[0101]
The emulsion polymerization method uses, for example, water or a mixed solvent of water and an organic solvent miscible with water (for example, methanol, ethanol, acetone, etc.) as a dispersion medium, and a monomer mixture of 5 to 40% by weight with respect to the dispersion medium. The polymerization is carried out with stirring at 0.05 to 5% by weight of the polymerization initiator and 0.1 to 20% by weight of the emulsifier and about 30 to 100 ° C., preferably 60 to 90 ° C. for 3 to 8 hours. Is done.
Conditions such as the dispersion medium, monomer concentration, initiator amount, emulsifier amount, reaction temperature, time, monomer addition method, and the like are appropriately set in consideration of the type of monomer used and the target particle size of the particles.
[0102]
Initiators preferably used for emulsion polymerization include inorganic peroxides such as potassium persulfate, sodium persulfate and ammonium persulfate, azonitrile compounds such as sodium salt of azobiscyanovaleric acid, 2,2′-azobis (2-amidinopropane) ) Azoamidine compounds such as dihydrochloride, cyclic azoamidine compounds such as 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] hydrochloride, 2,2′-azobis {2- And azoamide compounds such as methyl-N- [1,1′-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}. Among these, potassium persulfate, sodium persulfate, and ammonium persulfate are particularly preferable.
[0103]
As the dispersant, any of an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant can be used, and an anionic surfactant is preferable.
[0104]
The high Tg latex can be easily synthesized according to the usual emulsion polymerization method. A general emulsion polymerization method is described in detail in the following book.
"Synthetic Resin Emulsions (Hiraku Okuda, Hiroshi Inagaki, Published by Polymer Press (1978))", "Application of Synthetic Latex (Takaaki Sugimura, Tatsuo Kataoka, Junichi Suzuki, Keiji Kasahara, Published by Koshihara Press (1993)) ”,“ Synthetic Latex Chemistry (Muroichi Muroi, published by Kobunshi Shuppankai (1970)) ”.
[0105]
The synthesis of high Tg latex will be described in detail below with specific synthesis examples.
Synthesis example 1
Styrene 90 g, acrylic acid 3 g, distilled water 160 g, and surfactant (Sandet BL (manufactured by Sanyo Kasei Co., Ltd.)) 2 g are placed in a glass autoclave (TEM-V1000 manufactured by Pressure Glass Co., Ltd.) under a nitrogen stream. For 1 hour. Thereafter, the reaction vessel was sealed, 7 g of butadiene was added, and the temperature was raised to 60 ° C. 10 g of an aqueous potassium persulfate solution (5%) was added thereto, and the mixture was allowed to react with stirring for 10 hours. After the reaction, the temperature was lowered to room temperature, and 60 g of distilled water was added and stirred for 30 minutes to obtain 327 g of latex g of milky white liquid.
This dispersion was a fine latex liquid having a non-volatile content of 30.2% by mass and an average particle diameter of 76 nm. The particle size was evaluated by a dynamic light scattering method using a particle measuring apparatus N4 manufactured by Coulter.
[0106]
Synthesis example 2
A 500 ml three-necked flask equipped with a condenser and a stirrer is charged with a solution obtained by dissolving 2 g of sodium dodecyl sulfate as a surfactant in 250 ml of distilled water, and then a mixed solution of 80 g of styrene, 15 g of 2-ethylhexyl acrylate and 5 g of acrylic acid is added. The mixture was stirred at a rate of 200 rpm under a nitrogen stream. This reaction solution was heated to 75 ° C., and a solution prepared by dissolving 0.2 g of potassium persulfate in 10 ml of distilled water was added and polymerized for 2 hours. Further, a solution prepared by dissolving 0.2 g of potassium persulfate in 10 ml of distilled water was added and polymerized for 2 hours.
The reaction solution is cooled to room temperature, dialyzed using a cellulose membrane having a molecular weight cut off of 10,000, excess surfactant and inorganic salts are removed, concentrated under reduced pressure, and insoluble matter is removed by filtration to remove fine particles. 380 g of a milky white dispersion was obtained.
This dispersion was a fine latex liquid having an average particle diameter of 66 nm and containing 26.3% by weight of a nonvolatile content.
[0107]
Other high Tg latex used in the present invention can be easily synthesized by the same method as described above.
[0108]
The amount of high Tg latex used is 1 m of the sensitive material.²It can be used in the range of 1 to 20 g per unit, more preferably in the range of 1 to 15 g. It may be used by blending with two or more kinds of other high Tg latex of the present invention, or may be used in combination with other latex or polymer binder not included in the present invention.
[0109]
(Preferable solvent for coating solution)
In the present invention, the solvent of the organic silver salt-containing layer coating solution of the light-sensitive material (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is preferably an aqueous solvent containing 30% by mass or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent of the coating solution is preferably 50% by mass or more, more preferably 70% by mass or more.
Examples of preferred solvent compositions include water, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / Ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, etc. (numerical values are mass%).
[0110]
(Description of antifogging agent)
Antifoggants, stabilizers and stabilizer precursors that can be used in the present invention, paragraph No. 0070 of JP-A-10-62899, page 20 line 57 to page 21 line 7 of European Patent Publication No. 0808374A1 And the compounds described in JP-A-9-281637 and 9-329864.
In the present invention, it is necessary to contain an organic polyhalide as an antifoggant. By containing an appropriate amount of the polyhalogen compound, a remarkable effect of improving the image storage stability can be obtained.
As these, those disclosed in the patents described in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021 can be mentioned. In particular, organic halogen compounds represented by the formula (P) in Japanese Patent Application No. 11-87297, organic polyhalogen compounds represented by the general formula (II) in Japanese Patent Application Laid-Open No. 10-339934, and Japanese Patent Application No. 11-205330 The organic polyhalogen compounds described are preferred.
[0111]
(Description of polyhalogen compounds)
Hereinafter, the organic polyhalogen compound preferable in the present invention will be specifically described. A preferred polyhalogen compound of the present invention is a compound represented by the following general formula (H).
[0112]
General formula (H)
Q- (Y) n-C (Z₁) (Z₂) X
[0113]
  In the general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, and Y represents-SO ₂ −Where n is1Represents Z₁And Z₂Represents a halogen atom, and X represents a hydrogen atom or an electron-withdrawing group. In the general formula (H), Q preferably represents a phenyl group substituted with an electron-withdrawing group having a positive Hammett's substituent constant σp. Regarding the Hammett's substituent constant, Journal of Medicinal Chemistry, 1973, Vol. 16, No. 11, 1207-1216, etc. can be referred to.
[0114]
Examples of such electron-withdrawing groups include halogen atoms (fluorine atoms (σp value: 0.06), chlorine atoms (σp value: 0.23), bromine atoms (σp value: 0.23), iodine atoms ( σp value: 0.18)), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp value: 0.54)), cyano Group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σp value: 0.72)), aliphatic / aryl or Heterocyclic acyl groups (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), alkynyl groups (for example, C≡CH (σp value: 0.23)), aliphatic / aryl Or heterocyclic oxycarbo Group (for example, methoxycarbonyl (σp value: 0.45), phenoxycarbonyl (σp value: 0.44)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), Examples thereof include a sulfoxide group, a heterocyclic group, and a phosphoryl group.
The σp value is preferably in the range of 0.2 to 2.0, more preferably in the range of 0.4 to 1.0.
[0115]
Particularly preferred as an electron-withdrawing group is a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group, or an alkylphosphoryl group, with a carbamoyl group being most preferred.
[0116]
  X is preferably an electron-withdrawing group, more preferably a halogen atom, aliphatic / aryl or heterocyclic sulfonyl group, aliphatic / aryl or heterocyclic acyl group, aliphatic / aryl or heterocyclic oxycarbonyl group, carbamoyl A sulfamoyl group, particularly preferably a halogen atom. Among the halogen atoms, a chlorine atom, a bromine atom and an iodine atom are preferable, a chlorine atom and a bromine atom are more preferable, and a bromine atom is particularly preferable.
  Y is-SO ₂ −It is. n is1It is.
[0117]
Although the specific example of the compound of general formula (H) of this invention is shown below, this invention is not limited to these.
[0118]
[Chemical 9]

[0119]
[Chemical Formula 10]

[0120]
The compound represented by the general formula (H) of the present invention is 10 per mole of the non-photosensitive organic silver salt of the image forming layer.^-3It is preferable to use in the range of ~ 0.8 mol, more preferably 10^-3In the range of ~ 0.1 mol, more preferably 5 × 10^-3It is preferable to use in the range of ˜0.05 mol.
Particularly in the light-sensitive material using high silver iodide of the present invention, the addition amount of this polyhalogen compound is important, and 5 × 10 5 per mole of non-photosensitive organic silver salt.^-3It is especially preferable that it is -0.03 mol or less.
In the present invention, the antifoggant is added to the light-sensitive material by the method described in the method for containing a reducing agent, and the organic polyhalogen compound is also preferably added as a solid fine particle dispersion.
[0121]
(Other antifoggants)
Examples of other antifoggants include mercury (II) salts of paragraph No. 0113 of JP-A-11-65021, benzoic acids of paragraph No. 0114 of the same, salicylic acid derivatives of JP-A-2000-206642, and formulas of JP-A-2000-221634 A formalin scavenger compound represented by (S), a triazine compound according to claim 9 of JP-A-11-352624, a compound represented by formula (III) of JP-A-61-11791, 4-hydroxy-6-6 And methyl-1,3,3a, 7-tetrazaindene and the like.
[0122]
The photothermographic material in the invention may contain an azolium salt for the purpose of fog prevention. Examples of the azolium salt include compounds represented by general formula (XI) described in JP-A-59-193447, compounds described in JP-B-55-12581, and general formula (II) described in JP-A-60-153039. And the compounds represented. The azolium salt may be added to any part of the photosensitive material, but the addition layer is preferably added to the layer having the photosensitive layer, and more preferably to the organic silver salt-containing layer.
The azolium salt may be added at any step in the coating solution preparation. When added to the organic silver salt-containing layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. To immediately before coating. The azolium salt may be added by any method such as powder, solution, fine particle dispersion. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent.
[0123]
In the present invention, any amount of the azolium salt may be added, but 1 × 10 10 per silver mole.^-6Preferred is 1 mol or more and 2 mol or less.^-3More preferably, it is more than mol and less than 0.5 mol.
[0124]
In the present invention, a mercapto compound, a disulfide compound, and a thione compound can be contained in order to suppress or promote development to control development, to improve spectral sensitization efficiency, and to improve storage stability before and after development. JP-A-10-62899, paragraphs 0067 to 0069, JP-A-10-186572, the compound represented by the general formula (I) and specific examples thereof, paragraphs 0033 to 0052, and EP 080364A1 20 pages, lines 36 to 56, and Japanese Patent Application No. 11-273670. Of these, mercapto-substituted heteroaromatic compounds are preferred.
[0125]
(Description of color preparation)
In the photothermographic material of the present invention, it is preferable to add a color toning agent. For the color toning agent, paragraph numbers 0054 to 0055 of JP-A-10-62899, page 21 lines 23 to 48 of European Patent Publication No. 0803684A1, No. 2000-356317 and Japanese Patent Application No. 2000-187298. In particular, phthalazinones (phthalazinone, phthalazinone derivatives or metal salts; for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5, 7 -Dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione); phthalazinones and phthalic acids (eg phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, diammonium phthalate, sodium phthalate) , Potassium phthalate and tetrachlorophthalic anhydride); phthalazines (phthalazine, phthalazine derivatives or metal salts; 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6-t-butylphthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine and 2,3-dihydrophthalazine); phthalazines and phthalates A combination with acids is preferable, and a combination with phthalazines and phthalic acids is particularly preferable in combination with high silver iodide.
[0126]
The amount of phthalazine added is preferably 0.01 mol or more and 0.3 mol or less, more preferably 0.02 mol or more and 0.2 mol or less, per mol of silver behenate. Particularly preferably, the amount is from 0.02 mol to 0.1 mol. The amount of the phthalazine added is important for the acceleration of development which is a problem in the silver iodide emulsion of the present invention. By selecting an appropriate addition amount, both developability and covering can be achieved.
[0127]
(Other additives)
Regarding the plasticizer and lubricant that can be used in the photosensitive layer of the present invention, paragraph No. 0117 of JP-A No. 11-65021, the ultrahigh contrast agent for ultrahigh contrast image formation, and the addition method and amount thereof are the same. Paragraph No. 0118, Japanese Patent Application Laid-Open No. 11-223898, Paragraph Nos. 0136 to 0193, Japanese Patent Application No. 11-87297, compounds of formula (H), formulas (1) to (3), formulas (A) and (B), JP-A No. 11-65021, paragraph No. 0102, JP-A No. 11-91652, compounds of general formulas (III) to (V) (specific compounds: Chemical formulas 21 to 24), and contrast accelerators described in Japanese Patent Application No. 11-91652 -223898 paragraph number 0194-0195.
[0128]
In order to use formic acid or formate as a strong fogging substance, it is preferably contained in an amount of 5 mmol or less, more preferably 1 mmol or less per mol of silver on the side having an image forming layer containing photosensitive silver halide.
[0129]
When the ultrahigh contrast agent is used in the photothermographic material of the present invention, it is preferable to use an acid formed by hydrating diphosphorus pentoxide or a salt thereof in combination. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametalin An acid (salt) etc. can be mentioned.
Examples of the acid or salt thereof formed by hydrating diphosphorus pentoxide particularly preferably include orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific examples of the salt include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate.
Amount of acid or salt thereof formed by hydration of diphosphorus pentoxide (1m photosensitive material)²The coating amount per unit) may be a desired amount according to the performance such as sensitivity and fog, but 0.1 to 500 mg / m²Is preferably 0.5 to 100 mg / m²Is more preferable.
[0130]
(Explanation of layer structure)
In the photothermographic material of the invention, a surface protective layer can be provided for the purpose of preventing adhesion of the image forming layer. The surface protective layer may be a single layer or a plurality of layers. The surface protective layer is described in JP-A No. 11-65021, paragraph numbers 0119 to 0120 and Japanese Patent Application No. 2000-171936.
[0131]
As the binder for the surface protective layer of the present invention, gelatin is preferable, but it is also preferable to use polyvinyl alcohol (PVA) or a combination thereof. As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801), and the like can be used.
[0132]
Examples of PVA include those described in paragraph Nos. 0009 to 0020 of JP-A No. 2000-171936. Completely saponified PVA-105, partially saponified PVA-205, PVA-335, and modified polyvinyl alcohol MP- Preferred is 203 (trade name, manufactured by Kuraray Co., Ltd.).
Polyvinyl alcohol coating amount of protective layer (per layer) (support 1m²Per unit) as 0.3 to 4.0 g / m²Is preferable, 0.3 to 2.0 g / m²Is more preferable.
[0133]
In particular, when the photothermographic material of the present invention is used for printing applications in which dimensional change is a problem, it is preferable to use a polymer latex for the surface protective layer or the back layer.
For such polymer latex, “Synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Publishing (1978))”, “Application of synthetic latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara, Takashi "Molecular Publications (1993))" and "Synthetic Latex Chemistry (Muroichi Muroi, published by High Polymers Publication (1970))", specifically, methyl methacrylate (33.5% by mass) / Ethyl acrylate (50 wt%) / methacrylic acid (16.5 wt%) copolymer latex, methyl methacrylate (47.5 wt%) / butadiene (47.5 wt%) / itaconic acid (5 wt%) copolymer Latex, latex of ethyl acrylate (50% by weight) / methacrylic acid (50% by weight) copolymer, methyl methacrylate ( 8.9 mass%) / 2-ethylhexyl acrylate (25.4 mass%) / styrene (8.6 mass%) / 2-hydroxyethyl methacrylate (5.1 mass%) / acrylic acid (2.0 mass%) Latex of copolymer, methyl methacrylate (64.0% by mass) / styrene (9.0% by mass) / butyl acrylate (20.0% by mass) / 2-hydroxyethyl methacrylate (5.0% by mass) / acrylic acid (2 0.0% by weight) copolymer latex and the like.
[0134]
Further, as a binder for the surface protective layer, a combination of polymer latex described in Japanese Patent Application No. 11-6872 and the technique described in Paragraph Nos. 0021 to 0025 of Japanese Patent Application No. 11-143058, The technique described in paragraph Nos. 0027 to 0028 of the specification of 6872 and the technique described in paragraph Nos. 0023 to 0041 of the specification of Japanese Patent Application No. 10-199626 may be applied.
[0135]
The ratio of the polymer latex in the surface protective layer is preferably 10% by mass or more and 90% by mass or less, and particularly preferably 20% by mass or more and 80% by mass or less of the total binder.
Total binder (including water-soluble polymer and latex polymer) coating amount of surface protective layer (per layer) (support 1m)²As per) 0.3 to 5.0 g / m²Is preferable, 0.3 to 2.0 g / m²Is more preferable.
[0136]
The preparation temperature of the image forming layer coating solution of the present invention is preferably from 30 ° C. to 65 ° C., more preferably from 35 ° C. to less than 60 ° C., and more preferably from 35 ° C. to 55 ° C. Moreover, it is preferable that the temperature of the image forming layer coating liquid immediately after the addition of the polymer latex is maintained at 30 ° C. or higher and 65 ° C. or lower.
[0137]
The image forming layer of the present invention is composed of one or more layers on a support. When it is composed of one layer, it consists of an organic silver salt, photosensitive silver halide, a reducing agent which is a thermal developer, and a binder, and optionally contains additional materials such as toning agents, coating aids and other auxiliary agents. . In the case of two or more layers, an organic silver salt and a light-sensitive silver halide are contained in the first image forming layer (usually a layer adjacent to the support), and some in the second image forming layer or both layers. Must contain other ingredients.
The construction of a multicolor photosensitive photothermographic material may include a combination of these two layers for each color and includes all components in a single layer as described in US Pat. No. 4,708,928. Also good. In the case of a multi-dye multicolor photosensitive photothermographic material, each emulsion layer generally has a functional or non-functional barrier layer between each photosensitive layer as described in U.S. Pat.No. 4,460,681. By using, they are kept distinguished from each other.
[0138]
Various dyes and pigments (for example, CIPigment Blue 60, CIPigment Blue 64, and CIPigment Blue 15: 6) are used for the photosensitive layer of the present invention from the viewpoints of improving color tone, preventing interference fringes during laser exposure, and preventing irradiation. Can be used. These are described in detail in WO98 / 36322, JP-A-10-268465, JP-A-11-338098 and the like.
[0139]
In the photothermographic material of the present invention, the antihalation layer can be provided on the side far from the light source with respect to the photosensitive layer.
[0140]
The photothermographic material generally has a non-photosensitive layer in addition to the photosensitive layer. The non-photosensitive layer includes (1) a protective layer provided on the photosensitive layer (on the side farther from the support), and (2) a plurality of photosensitive layers or between the photosensitive layer and the protective layer. (3) an undercoat layer provided between the photosensitive layer and the support, and (4) a back layer provided on the opposite side of the photosensitive layer. The filter layer is provided on the photosensitive material as the layer (1) or (2). The antihalation layer is provided on the photosensitive material as the layer (3) or (4).
[0141]
For the antihalation layer, paragraphs 0123 to 0124 of JP-A-11-65021, JP-A-11-223898, 9-230531, 10-36695, 10-104779, 11-231457, 11 -352625, 11-352626, etc.
The antihalation layer contains an antihalation dye having absorption at the exposure wavelength. When the exposure wavelength is in the infrared region, an infrared absorbing dye may be used, and in that case, a dye having no absorption in the visible region is preferable.
When antihalation is performed using a dye having absorption in the visible range, it is preferable that substantially no dye color remains after image formation, and a means for decoloring by the heat of heat development is used. In particular, it is preferable to add a thermally decolorable dye and a base precursor to the non-photosensitive layer to function as an antihalation layer.
These techniques are described in JP-A-11-231457 and the like.
[0142]
The amount of decoloring dye added is determined by the use of the dye. In general, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably 0.2-2. The amount of dye used to obtain such an optical density is generally 0.001 to 1 g / m.²Degree.
[0143]
When the dye is decolored in this way, the optical density after heat development can be reduced to 0.1 or less. Two or more kinds of decoloring dyes may be used in combination in a heat decoloring type recording material or a photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.
In the thermal decoloration using such decoloring dye and base precursor, a substance (for example, diphenylsulfone, which lowers the melting point by 3 ° C. (deg) or more when mixed with a base precursor as described in JP-A-11-352626). 4-Chlorophenyl (phenyl) sulfone) is preferably used in view of thermal decoloring properties.
[0144]
In the present invention, a colorant having an absorption maximum at 300 to 450 nm can be added for the purpose of improving the silver color tone and the temporal change of the image. Such colorants are disclosed in JP-A Nos. 62-210458, 63-104046, 63-103235, 63-208846, 63-306436, 63-314535, and JP-A-01-61745. And Japanese Patent Application No. 11-276751.
Such colorants are typically 0.1 mg / m²~ 1g / m²The back layer provided on the opposite side of the photosensitive layer is preferable as the layer to be added in the range of.
[0145]
The photothermographic material in the invention is preferably a so-called single-sided photosensitive material having a photosensitive layer containing at least a silver halide emulsion on one side of a support and a back layer on the other side.
[0146]
In the present invention, it is preferable to add a matting agent for improving transportability, and the matting agent is described in paragraph Nos. 0126 to 0127 of JP-A No. 11-65021. Matting agent is photosensitive material 1m²When expressed in a coating amount per unit, preferably 1 to 400 mg / m², More preferably 5 to 300 mg / m²It is.
Further, the matte degree of the emulsion surface may be any as long as a so-called stardust failure in which small white spots occur in the image area and light leakage occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less. It is preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness can be easily obtained by Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479.
[0147]
In the present invention, the matte degree of the back layer is preferably a Beck smoothness of 1200 seconds or less and 10 seconds or more, preferably 800 seconds or less and 20 seconds or more, and more preferably 500 seconds or less and 40 seconds or more.
[0148]
In the present invention, the matting agent is preferably contained in the outermost surface layer of the photosensitive material, the layer functioning as the outermost surface layer, or a layer close to the outer surface, and is contained in a layer acting as a so-called protective layer. It is preferable.
[0149]
The back layer applicable to the present invention is described in paragraph numbers 0128 to 0130 of JP-A No. 11-65021.
[0150]
The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less, more preferably 6.6 or less before heat development. The lower limit is not particularly limited, but is about 3. The most preferred pH range is in the range of 4 to 6.2.
The film surface pH is preferably adjusted using an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, or a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is volatile and is preferable for achieving a low film surface pH because it can be removed before the coating process or heat development.
In addition, it is also preferable to use ammonia in combination with a nonvolatile base such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. The method for measuring the film surface pH is described in paragraph No. 0123 of Japanese Patent Application No. 11-87297.
[0151]
A hardener may be used for each layer such as the photosensitive layer, protective layer, and back layer of the present invention. Examples of hardeners are THJames' “THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION” (Macmillan Publishing Co., Inc., published in 1977), each of the methods described on pages 77 to 87. , 4-dichloro-6-hydroxy-s-triazine sodium salt, N, N-ethylenebis (vinylsulfonacetamide), N, N-propylenebis (vinylsulfonacetamide) and polyvalent metals described on page 78 of the same book Ions, polyisocyanates such as US Pat. No. 4,281,060 and JP-A-6-208193, epoxy compounds such as US Pat. No. 4,791,042, and vinyl sulfone compounds such as JP-A 62-89048 are preferably used.
[0152]
The hardening agent is added as a solution, and the addition time of this solution into the protective layer coating solution is from 180 minutes before to immediately before application, preferably from 60 minutes to 10 seconds before application. As long as the effects of the present invention are sufficiently exhibited, there is no particular limitation.
Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid delivered to the coater is the desired time, and by N. Harnby, MFEdwards, AWNienow, Takahashi There is a method of using a static mixer or the like described in Chapter 8 of the translation of Koji “Liquid Mixing Technology” (published by Nikkan Kogyo Shimbun, 1989).
[0153]
JP-A-11-65021 paragraph number 0132 for surfactants applicable to the present invention, paragraph number 0133 for solvents, paragraph number 0134 for supports, paragraph number for antistatic or conductive layers The method for obtaining a color image is described in paragraph No. 0136 of the same publication, and the slip agent is described in paragraph Nos. 0061 to 0064 of JP-A No. 11-84573 and paragraph Nos. 0049 to 0062 of Japanese Patent Application No. 11-106881.
[0154]
The transparent support is a polyester, particularly polyethylene, which has been heat-treated in a temperature range of 130 to 185 ° C. in order to relieve internal strain remaining in the film during biaxial stretching and to eliminate thermal shrinkage strain generated during heat development. Terephthalate is preferably used.
In the case of a photothermographic material for medical use, the transparent support may be colored with a blue dye (for example, dye-1 described in Examples of JP-A-8-240877) or may be uncolored.
[0155]
Examples of the support include water-soluble polyesters disclosed in JP-A-11-84574, styrene-butadiene copolymers described in JP-A-10-186565, and vinylidene chloride described in JP-A-2000-39684 and JP-A-11-106881, paragraphs 0063 to 0080. It is preferable to apply an undercoating technique such as a copolymer. Further, regarding the antistatic layer or the undercoat, JP-A-56-143430, JP-A-56-143431, JP-A-58-62646, JP-A-56-120519, JP-A-11-84573, paragraphs 0040 to 0051, U.S. Pat. The techniques described in paragraph Nos. 0078 to 0084 of 5,575,957 and JP-A-11-223898 can be applied.
[0156]
The photothermographic material is preferably a mono-sheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material).
[0157]
An antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, or a coating aid may be further added to the photothermographic material. Various additives are added to either the photosensitive layer or the non-photosensitive layer. For these, reference can be made to WO98 / 36322, EP803764A1, JP-A-10-186567, 10-18568 and the like.
[0158]
The photothermographic material in the invention may be applied by any method. Specifically, various coating operations are used, including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in U.S. Pat. Stephen F. Kistler, Petert M. Schweizer “LIQUID FILM COATING” (CHAPMAN & HALL, 1997) pages 399 to 536, preferably used for extrusion coating or slide coating, particularly preferably used for slide coating It is done. An example of the shape of the slide coater used for slide coating is shown in Figure 11b.1 on page 427 of the same book. If desired, two or more layers can be simultaneously coated by the method described in pages 399 to 536 of the same document, the method described in US Pat. No. 2,761,791 and British Patent No. 837,095.
[0159]
The organic silver salt-containing layer coating solution in the present invention is preferably a so-called thixotropic fluid. Regarding this technique, JP-A-11-52509 can be referred to.
The organic silver salt-containing layer coating solution in the present invention has a shear rate of 0.1 S.^-1The viscosity is preferably 400 mPa · s or more and 100,000 mPa · s or less, more preferably 500 mPa · s or more and 20000 mPa · s or less.
Also, shear rate 1000S^-1Is preferably 1 mPa · s or more and 200 mPa · s or less, and more preferably 5 mPa · s or more and 80 mPa · s or less.
[0160]
The photothermographic material of the present invention is preferably subjected to a heat treatment immediately after coating and drying in order to improve film formability. The temperature of the heat treatment is preferably in the range of 60 ° C. to 100 ° C. as the film surface temperature, and the heating time is preferably in the range of 1 second to 60 seconds. A more preferable range is a film surface temperature of 70 ° C. to 90 ° C. and a heating time of 2 seconds to 10 seconds. A preferable heat treatment method of the present invention is described in JP-A No. 2002-107872.
[0161]
Techniques that can be used for the photothermographic material of the present invention include EP803764A1, EP883022A1, WO98 / 36322, JP 56-62648, 58-62644, JP 9-43766, and 9- 281637, 9-297367, 9-304869, 9-311405, 9-329865, 10-10669, 10-62899, 10-69023, 10-186568, 10-90823, 10-171063, 10-186565, 10-186567, 10-186569 to 10-186572, 10-197974, 10-197982, 10 -197983, 10-197985 to 10-197987, 10-207001, 10-207004, 10-221807, 10-282601, 10-288823, 10-288823, 10-288824 10-307365, 10-312038, 10-339934, 11-7100, 11-15105, 11-24200, 11-24201, 11-30832, 11-84574, 11-65021, 11-109547, 11-125880, 11-129629, 11-133536 to 11-133539, 11-133542, 11 -133543, 11-223898, 11-352627, 11-305377, 11-305378, 11-305384, 11-305380, 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11- No. 343420, No. 2000-187298, No. 2000-10229, No. 2000-47345, No. 2000-206642, No. 2000-98530, No. 2000-98531, No. 2000-112059, No. 2000-112060 No., 2000-112104, 2000-112064, 2000-171936.
[0162]
(Description of packaging materials)
The light-sensitive material of the present invention is preferably packaged with a packaging material having low oxygen permeability and / or moisture permeability in order to suppress fluctuations in photographic performance during raw storage or to improve curling, curling, and the like. Specific examples of the packaging material having a low oxygen permeability and / or moisture permeability are disclosed in, for example, JP-A-8-254793. This is a packaging material described in JP-A-2000-206653.
[0163]
(Explanation of heat development)
The photothermographic material of the present invention may be developed by any method, but is usually developed by raising the temperature of the photothermographic material exposed imagewise. The preferred development temperature is 80 to 250 ° C, more preferably 100 to 140 ° C. In particular, the effect of the present invention is remarkably exhibited under the development condition at a development temperature of 110 to 130 ° C. More preferably, it is 115 degreeC or more and 130 or less.
At a development temperature of 110 ° C. or less, the high silver iodide emulsion used in the present invention exhibits a development progress comparable to that of conventionally known high silver bromide emulsions. However, when the development temperature is raised to 110 ° C. or higher, the conventional light-sensitive material using a high silver iodide emulsion is accompanied by a remarkable deterioration in development progress as compared with a high silver bromide emulsion. Development progress can be ensured even under various development conditions.
The development time is preferably 1 to 60 seconds, more preferably 5 to 30 seconds, and particularly preferably 10 to 20 seconds.
[0164]
A plate heater method is preferred as the heat development method. The heat development method using the plate heater method is preferably the method described in JP-A-11-133572. The heat development photosensitive material having a latent image formed thereon is brought into contact with the heating means in the heat development section to obtain a visible image. In the developing device, the heating unit includes a plate heater, and a plurality of press rollers are disposed to face each other along one surface of the plate heater, and the heat is interposed between the press roller and the plate heater. A thermal development apparatus that performs thermal development by passing a development photosensitive material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature about 1 to 10 ° C. at the tip.
Such a method is also described in JP-A-54-30032, which can exclude moisture and organic solvents contained in the photothermographic material out of the system, and can be rapidly developed in the photothermographic material. It is also possible to suppress changes in the shape of the support of the photothermographic material due to heating of the photothermographic material.
[0165]
The light-sensitive material of the present invention is preferably a laser beam as an exposure light source. High silver iodide emulsions preferably used in the present invention have been problematic because of their low sensitivity. However, it has been found that the high silver iodide emulsion of the present invention can record an image with less energy when exposed to light having a high illuminance such as a laser beam. The target sensitivity can be achieved by writing with such strong light in a short time.
[0166]
In particular, when an exposure amount giving the maximum density is given, the preferable illuminance on the surface of the photosensitive material is 0.1 W / mm.²100W / mm or more²It is preferable to expose with the illuminance as follows. More preferably 0.5 W / mm²50W / mm or more²It is as follows. More preferably 1 W / mm²50W / mm or more²The following is preferable.
[0167]
As the laser light according to the present invention, a gas laser (Ar⁺, He-Ne), YAG laser, dye laser, semiconductor laser and the like are preferable. A semiconductor laser and a second harmonic generation element can also be used. Red to infrared emission gas or semiconductor laser is preferable. A preferable wavelength of the laser beam is 600 nm or more and 900 nm or less. Particularly preferably, it is 620 nm or more and 850 nm or less.
It is also preferable that the laser light oscillates vertically in a multi-frequency manner such as high frequency superposition. The vertical multi means that the exposure wavelength is not single, and the exposure wavelength distribution is usually 5 nm or more, preferably 10 nm or more.
[0168]
As a medical laser imager provided with an exposure part and a heat development part, Fuji Medical Dry Laser Imager FM-DPL can be mentioned. FM-DPL is described in Fuji Medical Review No. 8, pages 39 to 55, and it goes without saying that these techniques are applied as a laser imager of the photothermographic material of the present invention. Further, it can also be applied as a photothermographic material for a laser imager in an “AD network” proposed by Fuji Medical System as a network system adapted to the DICOM standard.
[0169]
The photothermographic material of the present invention forms a black and white image by a silver image, and is used as a photothermographic material for medical diagnosis, a photothermographic material for industrial photography, a photothermographic material for printing, and a photothermographic material for COM. It is preferably used.
[0170]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
[0171]
Example 1
(Preparation of PET support)
PET having an intrinsic viscosity of IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (weight ratio) at 25 ° C.) was obtained using terephthalic acid and ethylene glycol according to a conventional method. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die and quenched, and an unstretched film having a thickness of 175 μm after heat setting was prepared.
[0172]
This was longitudinally stretched 3.3 times using rolls having different peripheral speeds and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Then, after heat setting at 240 ° C. for 20 seconds, the film was relaxed by 4% in the lateral direction at the same temperature. Then, after slitting the chuck part of the tenter, knurling is performed on both ends, and 4 kg / cm.²And a roll having a thickness of 175 μm was obtained.
[0173]
(Surface corona treatment)
Using a solid state corona treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, the support is 0.375 kV · A · min / m.²It was found that the process was done. The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.
[0174]
(Create an undercoat support)
(1) Preparation of undercoat layer coating solution
Formulation (1) (for the undercoat layer on the photosensitive layer side)
59g pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Polyethylene glycol monononyl phenyl ether
(Average number of ethylene oxide = 8.5) 10% by mass solution 5.4g
MP-1000 (polymer fine particles, average particle size 0.4μm) 0.91g by Soken Chemical Co., Ltd.
935ml distilled water
[0175]
Formulation (2) (for back layer 1st layer)
Styrene-butadiene copolymer latex 158g
(Solid content 40% by mass, styrene / butadiene weight ratio = 68/32)
2,4-dichloro-6-hydroxy-S-
Triazine sodium salt 8% by weight aqueous solution 20g
10% 1% by weight aqueous solution of sodium laurylbenzenesulfonate
Distilled water 854ml
[0176]
Formula (3) (Back side 2nd layer)
SnO₂/ SbO (9/1 mass ratio, average particle size 0.038μm, 17 mass% dispersion) 84g
Gelatin (10 mass% aqueous solution) 89.2g
Metrows TC-5 (2% by weight aqueous solution) manufactured by Shin-Etsu Chemical Co., Ltd.8.6g
MP-1000 0.01g manufactured by Soken Chemical Co., Ltd.
10% 1% by weight aqueous solution of sodium dodecylbenzenesulfonate
NaOH (1% by mass) 6ml
Proxel (made by ICI) 1ml
805ml of distilled water
[0177]
(Preparation of undercoat support)
After both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm are subjected to the corona discharge treatment, the undercoat coating solution formulation {circle around (1)} is applied to one surface (photosensitive layer surface) with a wire bar. .6ml / m²(Per side) and dried at 180 ° C. for 5 minutes, and then the undercoat coating liquid formulation (2) is applied to the back side (back side) with a wire bar at a wet coating amount of 5.7 ml / m.²And then dried at 180 ° C. for 5 minutes. Further, the undercoat coating liquid formulation (3) is applied to the back surface (back surface) with a wire bar so that the wet coating amount is 7.7 ml / m.²And then dried at 180 ° C. for 6 minutes to prepare an undercoat support.
[0178]
(Preparation of back surface coating solution)
(Preparation of solid fine particle dispersion (a) of base precursor)
64 g of the base precursor compound 11, 28 g of diphenylsulfone and 10 g of the surfactant demole N manufactured by Kao Co., Ltd. were mixed with 220 ml of distilled water, and the mixture was mixed with a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.). To obtain a solid fine particle dispersion (a) of a base precursor compound having an average particle size of 0.2 μm.
[0179]
(Preparation of dye solid fine particle dispersion)
9.6 g of cyanine dye compound 13 and 5.8 g of sodium p-dodecylbenzenesulfonate are mixed with 305 ml of distilled water, and the mixture is beaded using a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.). Dispersion gave a dye solid fine particle dispersion having an average particle size of 0.2 μm.
[0180]
(Preparation of antihalation layer coating solution)
Gelatin 17 g, polyacrylamide 9.6 g, solid fine particle dispersion of the above-mentioned precursor ((a) 70 g, dye solid fine particle dispersion 56 g, monodispersed polymethyl methacrylate fine particles (average particle size 8 μm, particle size standard deviation 0.4) ) 1.5g, benzoisothiazolinone 0.03g, sodium polyethylene sulfonate 2.2g, blue dye compound 14 0.2g, yellow dye compound 15 3.9g, water 844ml mixed, antihalation layer coating solution Was prepared.
[0181]
(Preparation of back surface protective layer coating solution)
The container is kept at 40 ° C., 50 g of gelatin, 0.2 g of sodium polystyrenesulfonate, 2.4 g of N, N-ethylenebis (vinylsulfonacetamide), 1 g of sodium t-octylphenoxyethoxyethanesulfonate, 30 mg of benzoisothiazolinone , Fluorine-based surfactant (F-1: N-perfluorooctylsulfonyl-N-propylalanine potassium salt) 37 mg, fluorine-based surfactant (F-2: polyethylene glycol mono (N-perfluorooctylsulfonyl-N-) Propyl-2-aminoethyl) ether [ethylene oxide average polymerization degree 15]) 0.15 g, fluorosurfactant (F-3) 64 mg, fluorosurfactant (F-4) 32 mg, acrylic acid / ethyl acrylate Copolymer (copolymerization weight ratio 5/95) 8. g, Aerosol OT (manufactured by American Cyanamid Co.) 0.6 g, and the back surface protective layer coating liquid was 950ml mixing 1.8g, water and liquid paraffin emulsion as liquid paraffin.
[0182]
(Preparation of silver halide emulsion)
<< Preparation of silver halide emulsion 1 >>
To a solution of 1420 ml of distilled water was added 4.3 ml of a 1% by weight potassium iodide solution, and a solution containing 3.5 ml of 0.5 mol / L sulfuric acid and 36.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 42 ° C., a solution A in which distilled water was diluted to 22.56 g of silver nitrate and diluted to 195.6 ml and solution B in which 21.8 g of potassium iodide was diluted with distilled water to a volume of 218 ml were added at a constant flow rate. The whole amount was added over 9 minutes. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and further 10.8 ml of a 10% by mass aqueous solution of benzimidazole was added.
[0183]
Further, Solution C obtained by diluting 51.86 g of silver nitrate to 317.5 ml and diluting Solution I obtained by diluting 60 g of potassium iodide to a volume of 600 ml with distilled water was completely added over 120 minutes at a constant flow rate. Solution D was added by the controlled double jet method while maintaining pAg at 8.1. 1 x 10 per mole of silver^-FourThe total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so as to have a molarity. Also,
5 seconds after the end of the addition of solution C, an aqueous solution of potassium iron (II) hexacyanide was added at 3 × 10 5 per mol of silver.^-FourThe whole molar amount was added. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 8.0.
[0184]
While maintaining the silver halide dispersion at 38 ° C. with stirring, 5 ml of a methanol solution of 0.34% by mass of 1,2-benzisothiazolin-3-one was added, and after 40 minutes, the sensitizing dye A and the sensitizing dye A were increased. A methanol solution of 1: 1 in the molar ratio of dye B is 1.2 × 10 as the sum of sensitizing dyes A and B per mole of silver.^-3Mole was added and the temperature was raised to 47 ° C. after 1 minute.
20 minutes after the temperature rise, sodium benzenethiosulfonate was 7.6 × 10 6 in 1 mol of silver with a methanol solution.^-Five5 minutes later, tellurium sensitizer B was added in methanol solution to 2.9 × 10 6 per mole of silver.^-FourMole was added and aged for 91 minutes.
1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added, and after 4 minutes, 5-methyl-2-mercaptoben ヅ imidazole was added to the methanol solution at 4 per mole of silver. .8x10^-3Mole and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in a methanol solution at 5.4 × 10 5 per mole of silver^-3Mole and 1- (3-Methylureido) -5-mercaptotetrazole sodium salt in aqueous solution at 8.5 × 10 5 per mole of silver^-3A silver halide emulsion 1 was prepared by adding a molar amount.
[0185]
The grains in the prepared silver halide emulsion were pure silver iodide grains having an average sphere equivalent diameter of 0.040 μm and a sphere equivalent diameter variation coefficient of 78%. The particle size and the like were determined from an average of 1000 particles using an electron microscope.
[0186]
<< Preparation of mixed emulsion A for coating liquid >>
The silver halide emulsion 1 was dissolved, and benzothiazolium iodide was dissolved in a 1% by mass aqueous solution at 7 × 10 5 per mol of silver.^-3Mole was added. Further, 1- (3-methylureido)-was added so that the silver halide content per kg of the mixed emulsion for coating solution was 38.2 g as silver, and 0.34 g per kg of the mixed emulsion for coating solution. 5-mercaptotetrazole sodium salt was added.
[0187]
≪Preparation of fatty acid silver (organic silver salt) dispersion≫
Henkel behenic acid (product name Edenor C22-85R) 87.6Kg, distilled water 423L, 5mol / L NaOH aqueous solution 49.2L, tert-butanol 120L are mixed and stirred at 75 ° C for 1 hour to react. A sodium behenate solution was obtained. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of tert-butanol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution and the total amount of silver nitrate aqueous solution were 93 minutes and 15 seconds at a constant flow rate, respectively. Added over 90 minutes.
At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution, only the sodium behenate solution is added for 14 minutes and 15 seconds. It was made to be.
[0188]
At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The pipe of the addition system for the sodium behenate solution was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically around the stirring axis, and were adjusted so as not to contact the reaction solution.
[0189]
After completion of the addition of the sodium behenate solution, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.
[0190]
When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, average sphere equivalent diameter. It was a flake-like crystal having a variation coefficient of 15% for a sphere equivalent diameter of 0.52 μm. (A, b, and c are the provisions of the text)
[0191]
19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg, and the whole amount is set to 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.). : PM-10 type).
[0192]
Next, the pre-dispersed stock solution is subjected to a pressure of 1260 kg / cm of a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber).²And was treated three times to obtain a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.
[0193]
(Preparation of reducing agent dispersion)
<< Preparation of Reducing Agent Complex-3 Dispersion >>
Reducing agent complex-3 (1,2′-methylenebis- (4-ethyl-6-tert-butylphenol) and triphenylphosphine oxide 1: 1 complex) 10 kg, triphenylphosphine oxide 0.12 kg and modified polyvinyl alcohol (Kuraray) 7.2 kg of water was added to 16 kg of a 10 mass% aqueous solution of Poval MP203, manufactured by Co., Ltd., and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 4 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Corporation) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% by mass to obtain a reducing agent complex-3 dispersion.
The reducing agent complex particles contained in the reducing agent complex dispersion thus obtained had a median diameter of 0.46 μm and a maximum particle diameter of 1.6 μm or less. The obtained reducing agent complex dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign matters such as dust and stored.
[0194]
(Preparation of polyhalogen compound)
<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of organic polyhalogen compound-2 (tribromomethanesulfonylbenzene), 10 kg of 20 wt% aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of 20 wt% aqueous solution of sodium triisopropylnaphthalenesulfonate, Then, 14 kg of water was added and mixed well to obtain a slurry.
This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 26% by mass to obtain an organic polyhalogen compound-2 dispersion.
The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust and stored.
[0195]
<< Preparation of organic polyhalogen compound-3 dispersion >>
10 kg of organic polyhalogen compound-3 (N-butyl-3-tribromomethanesulfonylbenzamide), 20 kg of 10 wt% aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and 20 wt% of sodium triisopropylnaphthalenesulfonate A 0.4% aqueous solution and 8 kg of water were added and mixed well to obtain a slurry.
This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 25% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-3 dispersion.
The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.36 μm and a maximum particle diameter of 1.5 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
[0196]
<< Preparation of Phthalazine Compound-1 Solution >>
8 kg of modified polyvinyl alcohol MP203 manufactured by Kuraray Co., Ltd. was dissolved in 174.57 kg of water, and then 3.15 kg of a 20 wt% aqueous solution of sodium triisopropylnaphthalenesulfonate and 70 wt% of phthalazine compound-1 (6-isopropylphthalazine). % Aqueous solution 14.28 kg was added to prepare a 5 mass% solution of phthalazine compound-1.
[0197]
≪Preparation of mercapto compound-1 aqueous solution≫
7 g of mercapto compound-1 (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to obtain a 0.7% by mass aqueous solution.
[0198]
<< Preparation of Pigment-1 Dispersion >>
A slurry was prepared by adding 250 g of water to 64 g of C.I. Pigment Blue 60 and 6.4 g of Kamo Corp. demole N and mixing well. Prepare 800 g of zirconia beads having an average diameter of 0.5 mm, put them in a vessel together with the slurry, and disperse with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.) for 25 hours. Obtained.
The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.
[0199]
≪Preparation of SBR latex liquid≫
The SBR latex with Tg = 23 ° C. was prepared as follows.
In the same manner as in the above high Tg latex synthesis example, ammonium persulfate was used as a polymerization initiator, an anionic surfactant was used as an emulsifier, and 70.5 mass of styrene, 26.5 mass of butadiene and 3 mass of acrylic acid were emulsion-polymerized. Thereafter, aging was performed at 80 ° C. for 8 hours.
Thereafter, the mixture was cooled to 40 ° C., adjusted to pH 7.0 with aqueous ammonia, and Sandet BL manufactured by Sanyo Chemical Co., Ltd. was further added to 0.22%. Next, 5% aqueous sodium hydroxide solution was added to adjust the pH to 8.3, and further adjusted to pH 8.4 with aqueous ammonia. Na used at this time⁺Ion and NH_Four ⁺The molar ratio of ions was 1: 2.3.
Further, 0.15 ml of 7% aqueous solution of benzoisothiazoline non sodium salt was added to 1 kg of this liquid to prepare an SBR latex liquid.
[0200]
(SBR latex: Latex of -St (70.5) -Bu (26.5) -AA (3)-) Tg 23 ° C. average particle size 0.1 μm, concentration 43% by mass, equilibrium water content 0.6% at 25 ° C. 60% RH %, Ion conductivity 4.2 mS / cm (Ion conductivity is measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd., latex stock solution (43% by mass) measured at 25 ° C.), pH 8. 4
SBR latexes having different Tg were adjusted in the same manner by appropriately changing the ratio of styrene and butadiene.
[0201]
<< Preparation of emulsion layer (photosensitive layer) coating liquid-1 >>
1000 g of fatty acid silver dispersion obtained above, 104 ml of water, 30 g of pigment-1 dispersion, 6.3 g of organic polyhalogen compound-2 dispersion, 20.7 g of organic polyhalogen compound-3 dispersion, 173 g of phthalazine compound-1 solution , SBR latex (Tg: 23 ° C.) 1082 g, reducing agent complex-3 dispersion 258 g, mercapto compound-1 solution 9 g were sequentially added.Organic silver saltThe emulsion layer coating solution was added to the coating die as it was, and applied to the coating die.
[0202]
<Preparation of emulsion surface intermediate layer coating solution>
772 g of 10% by weight aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 5.3 g of pigment-1 dispersion, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio) 64/9/20/5/2) 226 g of a 27.5% by weight latex solution, 2 ml of a 5% by weight aqueous solution of aerosol OT (manufactured by American Cyanamid Co., Ltd.), and 10% by weight of a 20% by weight aqueous solution of diammonium phthalate salt Water was added to a total volume of 880 g and adjusted to a pH of 7.5 with NaOH to obtain an intermediate layer coating solution of 10 ml / m²Then, the solution was fed to the coating die.
The viscosity of the coating solution was 65 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).
[0203]
<< Preparation of emulsion surface protective layer first layer coating liquid >>
Inert gelatin (64 g) is dissolved in water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio 64/9/20/5/2) 27.5% by weight latex 80 g, 23 ml of a 10% by weight methanol solution of phthalic acid, 23 ml of a 10% by weight aqueous solution of 4-methylphthalic acid, 28 ml of sulfuric acid having a concentration of 0.5 mol / L, and a 5% by weight aqueous solution of Aerosol OT (American Cyanamid Co., Ltd.) Add 5 ml, 0.5 g phenoxyethanol, 0.1 g benzoisothiazolinone, add water to make a total amount of 750 g, and use 26 ml of 4% by weight chromium alum mixed with a static mixer just before coating. 18.6 ml / m²Then, the solution was fed to the coating die.
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).
[0204]
<Preparation of emulsion surface protective layer second layer coating solution>
Inert gelatin (80 g) is dissolved in water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio 64/9/20/5/2) 27.5% by weight of latex 102 g, 3.2 ml of a 5% by mass solution of a fluorosurfactant (F-1: N-perfluorooctylsulfonyl-N-propylalanine potassium salt), a fluorosurfactant (F-2: polyethylene glycol mono (N- Perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [ethylene oxide average polymerization degree = 15]) 2% by mass aqueous solution 32 ml, aerosol OT (manufactured by American Cyanamid Co., Ltd.) 5% mass solution 23 ml , 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm), Water was added to a total amount of 650 g in 21 g of dimethacrylate fine particles (average particle size: 4.5 μm), 1.6 g of 4-methylphthalic acid, 4.8 g of phthalic acid, 44 ml of 0.5 mol / L sulfuric acid, and 10 ml of benzoisothiazolinone. The solution obtained by adding 445 ml of an aqueous solution containing 4% by mass of chromium alum and 0.67% by mass of phthalic acid with a static mixer immediately before coating was used as the surface protective layer coating solution, 8.3 ml / m²Then, the solution was fed to the coating die.
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).
[0205]
<< Preparation of photothermographic material-1 >>
The anti-halation layer coating solution is applied to the back surface side of the undercoat support so that the solid content coating amount of the solid fine particle dye is 0.04 g / m.²In addition, the back surface protective layer coating solution has a gelatin coating amount of 1.7 g / m.²Then, a simultaneous multilayer coating was applied and dried to form a back layer.
[0206]
A photothermographic material sample was prepared on the surface opposite to the back surface by simultaneous multilayer coating by the slide bead coating method in the order of the emulsion layer, the intermediate layer, the protective layer first layer, and the protective layer second layer from the undercoat surface. . At this time, the emulsion layer and the intermediate layer were adjusted to 35 ° C., the protective layer first layer was adjusted to 36 ° C., and the protective layer first layer was adjusted to 37 ° C.
Coating amount of each compound in the emulsion layer (g / m²) Is as follows.
[0207]
Silver behenate 6.19
Pigment (C.I.Pigment Blue 60) 0.036
Polyhalogen compound-2 0.04
Polyhalogen compound-3 0.12
Phthalazine Compound-1 0.21
SBR latex 11.1
Reducing agent complex-3 1.54
Mercapto Compound-1 0.002
Silver halide (as Ag) Amounts listed in Table 1
[0208]
The coating and drying conditions are as follows.
The coating was performed at a speed of 160 m / min, the gap between the coating die tip and the support was set to 0.10 to 0.30 mm, and the pressure in the decompression chamber was set to be 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with an ion wind before coating.
In the subsequent chilling zone, after cooling the coating solution with a wind at a dry bulb temperature of 10 to 20 ° C., it is transported in a non-contact type, and is dried at a dry bulb temperature of 23 to 45 ° C. It dried with the dry wind of the wet bulb temperature 15-21 degreeC.
After drying, the humidity was adjusted at 25 ° C. and humidity of 40 to 60% RH, and then the film surface was heated to 70 to 90 ° C. After heating, the film surface was cooled to 25 ° C.
[0209]
The photothermographic material thus prepared had a Beck smoothness of 550 seconds on the photosensitive layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0.
[0210]
The chemical structures of the compounds used in the examples of the present invention are shown below.
[0211]
Embedded image

[0212]
Embedded image

[0213]
Embedded image

[0214]
Embedded image

[0215]
Embedded image

[0216]
The obtained samples were cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50%, stored at room temperature for 2 weeks, and then evaluated as follows.
(Packaging material)
PET 10 μm / PE 12 μm / Aluminum foil 9 μm / Ny 15 μm / Polyethylene 50% containing carbon 3%
Oxygen permeability: 0 ml / atm · m²・ 25 ℃ ・ day, moisture permeability: 0g / atm ・ m²・ 25 ℃ ・ day
[0217]
Example 2
In the same manner as in Example 1, except that silver halide emulsion 1 was used instead of silver halide emulsion 1, silver halide emulsions 2 to 6 having different grain sizes were prepared as shown in Table 1 by changing the temperature at the time of grain formation. . Similarly, emulsions 7 and 8 having different halogen compositions as shown in Table 1 were prepared by changing a part of potassium iodide to be used to potassium bromide, changing the amount and changing the added halogen composition.
Using these silver halide emulsions 1-8, photothermographic materials 2-14 as shown in Table 1 were prepared in the same manner as in Example 1 except that the coating amount of silver halide was changed.
[0218]
(Evaluation of photographic performance)
The sample was modified by Fuji Medical Dry Laser Imager FM-DPL and exposed and developed.
The exposure was performed by irradiating the light-sensitive material with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB) mounted on FM-DPL being reduced to 100 μm * 100 μm. The exposure was performed by changing the exposure amount of the laser stepwise.
Development was carried out using FM-DPL thermal development sections with the temperature of the four panel heaters set to 112 ° C-119 ° C-121 ° C-121 ° C. The development time was 24 seconds. In the evaluation of development progress, the thermal development time was changed by changing the conveyance speed.
Evaluation of the image obtained after exposure and development was performed by measuring the density with a Macbeth densitometer, and creating a density characteristic curve with respect to the exposure amount.
In the post-development sample, the density of the part not exposed to the laser was Dmin, and the density of the part exposed at the maximum exposure was Dmax. Further, the reciprocal of the exposure amount for obtaining a density of Dmin + 1.0 was defined as sensitivity, and expressed with respect to the reference photosensitive material.
[0219]
A development curve was created by changing the conveying speed of the thermal machine so that the development time was 16 seconds. As in the case of 24-second development, the sensitivity was the reciprocal of the exposure amount necessary to obtain a density of Dmin + 1.0. A value calculated by the following formula was evaluated as development progress from the sensitivity at 24 seconds development and the sensitivity at 16 seconds development.
[0220]
Development progress = Log (24 sec sensitivity / 16 sec sensitivity)
[0221]
Larger values indicate slower developability and are less stable with respect to changes in processing time. A smaller value is preferred.
[0222]
(Evaluation of printout performance) Condition 1
The treated sample was placed in an environment of 30 ° C. and 70%, and left for 3 days under a fluorescent lamp with an illuminance of 1000 lux. The increase in the density of the covered portion with respect to that before the treatment was defined as the printout performance.
[0223]
(Evaluation of printout performance) Condition 2
In the same manner as in condition 1, except that it was left for 10 days under a fluorescent lamp with an illuminance of 300 lux in an environment of 25 ° C. and 70%. The increase in the covering at this time was defined as the printout performance.
The results of evaluating samples 1 to 14 in this way are shown in Table 1.
[0224]
[Table 1]

[0225]
As is apparent from the results, it can be seen that the sample of the present invention is excellent in printout performance and excellent in development progress and Dmax performance. The high silver iodide emulsion of the present invention can achieve this performance by setting its size to 90 nm or less. It can also be seen that it is more preferable that the number of moles of the high silver iodide emulsion added to the organic silver salt is smaller.
[0226]
Example 3
It shows that the effect of the present invention can be achieved even by a method of converting an organic silver salt in contrast to the method of mixing silver halide before coating as in Examples 1 and 2.
[0227]
<Preparation of light-sensitive material containing high silver iodide emulsion by conversion method>
As in Example 1, except that, in << Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution-1 >>, instead of adding silver halide emulsion A, conversion of fatty acid silver was carried out by adding a KI solution, A photothermographic material was prepared in the same manner except that the same amount of sensitizing dyes A and B and 5-methyl-2-mercaptobenzimidazole as in Emulsion 1 were added per mole of silver halide.
Samples 15, 16, and 17 were prepared by changing the amount of KI added.
The samples 15 to 17 thus prepared and the samples 2, 4 and 8 of Example 2 were evaluated in the same manner as in Example 2. The results are shown in Table 2.
[0228]
[Table 2]

[0229]
In this way, the development acceleration effect of the present invention can be obtained even with a sample prepared by the conversion method. However, the sensitivity is low in the conversion method. The high silver iodide emulsion of the present invention is more preferably prepared in the absence of an organic silver salt.
[0230]
Example 4
Next, it is shown that the high silver iodide emulsion of the present invention is particularly preferable for exposure with high illuminance such as laser exposure.
The exposure by FM-DPL in Example 2 was 4 W / mm at the maximum output when the illuminance was measured.²Met. On the other hand, a xenon light source was used as a light source, and exposure was performed through a step wedge by light exposure. When the illuminance was measured, 3 mW / mm²Met. Exposure was performed so that the required density was obtained by adjusting the exposure time.
Samples 4 and 12 of Example 2 were each exposed under two conditions to determine sensitivity. Sensitivity was expressed as the reciprocal of the amount of light (= illuminance × time) required to obtain a density of Dmin + 1.0, where 100 was the sensitivity of each sample in laser exposure. The results are shown in Table 3.
[0231]
[Table 3]

[0232]
As can be seen from this example, it can be seen that the light-sensitive material using the high silver iodide emulsion of the present invention is particularly sensitive to high illumination exposure such as laser exposure.
[0233]
Example 5
In the present invention, a polyhalogen compound is essential. The effect is shown.
As in Example 1, except that the silver halide emulsion 1 and the silver halide emulsion 8 were used, and the ratios of the organic polysilver halide compounds 2 and 3 were kept the same, as shown in Table 4, and the addition amount was changed. Samples 20 to 25 were prepared.
The obtained sample was examined for Dmin, Dmax, printout condition 1 and condition 2 by the method described in Example 2. The results are shown in Table 4.
[0234]
[Table 4]

[0235]
As is apparent from Table 4, the characteristics of the high silver iodide emulsion of the present invention remarkably appear in the presence of the polysilver halide compound. Moreover, even if it tries to improve the printout performance of the photosensitive material of the comparative example with a small silver iodide content from Table 4 by increasing the amount of the polyhalogen compound, it is difficult to create a good printout situation in various environmental conditions. I understand.
The high silver iodide emulsion of the present invention can give good results even when the environment (temperature / humidity / light illuminance) in which such printout occurs changes.
[0236]
Example 6
A laser beam was oscillated in a longitudinal multimode by high-frequency superposition, and the same experiment as in Example 2 was performed. Similar results as in Example 2 were obtained.
[0237]
Example 7
A photothermographic material 26 was prepared in the same manner as Sample 4 in Example 2, except that emulsion 4 and emulsion 3 were mixed at 8: 2 instead of emulsion 1. As a result of evaluating in the same manner as in Example 2, favorable results were obtained.
[0238]
Example 8
A photothermographic material was prepared in the same manner as in Sample 3 of Example 2, except that the following compounds were used in place of the reducing agent complex.
[0239]
<< Preparation of Reducing Agent-5 Dispersion >>
10 kg of reducing agent-5 (2,2′-methylenebis- (4-methyl-6-tert-butylphenol)) and 20 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) were added with 6 kg of water. Add and mix well to make a slurry.
This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% by mass to obtain a reducing agent-5 dispersion.
The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.38 μm and a maximum particle diameter of 1.5 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
[0240]
<< Preparation of hydrogen bonding compound-2 dispersion >>
Add 10 kg of water to 10 kg of a 10% aqueous solution of hydrogen bonding compound-2 (tri (4-t-butylphenyl) phosphine oxide) and denatured polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203). Mix to make a slurry.
This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 22% by mass to obtain a hydrogen bonding compound-2 dispersion.
The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.35 μm and a maximum particle diameter of 1.5 μm or less. The obtained hydrogen bonding compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
[0241]
<< Creation of photothermographic material 27 >>
A photothermographic material 27 was prepared in the same manner as in Sample 3 of Example 2, except that reducing agent-5 and hydrogen bonding compound-2 were used instead of reducing agent-3. Coating amount of each compound in the emulsion layer (g / m²) Is as follows.
[0242]
Silver behenate 6.19
Reducing agent-5 0.76
Hydrogen bonding compound 2 0.59
Pigment (C.I.Pigment Blue 60) 0.032
Polyhalogen compound-2 0.04
Polyhalogen compound-3 0.12
Phthalazine Compound-1 0.21
SBR latex 11.1
Mercapto Compound-1 0.002
Silver halide (as Ag) 0.145
[0243]
As a result of evaluation in the same manner as in Example 2, a preferable compound was obtained.
[0244]
Example 9
A photothermographic material 28 was prepared in the same manner by using the compound of reducing agent-2 instead of the reducing agent-5 of Example 8 to prepare a dispersion.
As a result of changing the conveying speed of the heat developing machine and performing the developing process with a heat developing time of 14 seconds, preferable sensitivity and gradation were obtained.
[0245]
Example 10
The photographic performance was evaluated using the photosensitive materials 1 to 5, 9, 13, and 14 of the present invention. Evaluation of photographic performance was performed in the same manner as in Example 2, except that the set temperatures of the four heaters were all set to 108 ° C. The results are shown in Table 5.
[0246]
[Table 5]

[0247]
As is apparent from Table 5, the development progress of the light-sensitive material using the high silver iodide of the present invention is better than that of the light-sensitive material using high silver bromide at low temperature development such as 108 ° C. As can be seen from Table 1 (development temperature of 112 to 121 ° C.), when the development temperature is 110 ° C. or higher, high silver bromide is used and remarkable development suppression (deterioration of development progress) occurs compared to the photosensitive material (Sample 10 to 10). 12 and 13, 14), however, the photosensitive material of the present invention (samples 1 to 5 and the like) can obtain preferable development progress even under such conditions, and has high sensitivity and stability in development processing. Are better.
[0248]
【The invention's effect】
According to the present invention, it is possible to provide a photothermographic material having high sensitivity, excellent development processing stability and excellent optical image storage stability after processing.

Claims (12)

At least one selected from photosensitive silver halide, non-photosensitive organic silver salt having a silver behenate content of 50 mol% to 100%, a hindered phenol reducing agent and a bisphenol reducing agent on the support. In a photothermographic material of the type that contains a heat developer and a binder and is not heat-treated immediately before use, the photosensitive material contains an organic polyhalogen compound represented by the following general formula (H) , and the photosensitivity A photothermographic material comprising silver halide having a silver iodide content of 40 mol% to 100 mol% and an average grain size of 5 nm to 90 nm as silver halide. However, the photothermographic material does not contain a combination of a component that oxidizes free silver and a component that photooxidizes a reduced product of the component.
General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In the general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, Y represents —SO ₂ —, n represents ₁ , Z ₁ and Z ₂ represent a halogen atom, and X represents hydrogen. Represents an atomic or electron withdrawing group. The photothermographic material of claim 1, wherein the silver iodide content of the silver halide is not more than 100 mol% to 70 mol%. 3. The photothermographic material according to claim 1, wherein the silver iodide content of the silver halide is 90 mol% or more and 100 mol% or less. In any one of claims 1 to 3, the photothermographic material, wherein the average particle size of the silver halide is 5nm or more 70nm or less. In any of the claims 1-4, the photothermographic material characterized in that said silver halide is one that was formed in the absence status of the non-photosensitive organic silver salt. In any one of claims 1 to 5, heat-developable photosensitive material, wherein the coating amount of the silver halide is not more than 15 mol% 0.5 mol% or more of the non-photosensitive organic silver salt 1 mole . 7. The photothermographic material according to claim 6 , wherein the silver halide coating amount is 0.5 mol% or more and 12 mol% or less with respect to 1 mol of the non-photosensitive organic silver salt. 7. The photothermographic material according to claim 6 , wherein the silver halide coating amount is 0.5 mol% or more and 7 mol% or less with respect to 1 mol of the non-photosensitive organic silver salt. In any of the claims 6-8, photothermographic material characterized in that the photothermographic material is thermally developed in the developing temperature 110 ° C. or higher 130 ° C. or less. The photothermographic material according to any one of claims 1 to 9, characterized in that said silver halide is spectrally sensitized to have a spectral sensitivity peak at a wavelength of 600nm or more 900nm or less. Image forming method comprising exposing and recording the photothermographic material according to any one of claims 1 to 10 in a semiconductor laser. 12. The image forming method according to claim 11, wherein the exposure illuminance of the laser is 0.1 W / mm ² or more.