JP2004317778A - Heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material which suppresses a variation of gradation and an increase of fog during storage of the heat developable photosensitive material before use. <P>SOLUTION: The heat developable photosensitive material includes a photosensitive layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, a contrast enhancer and a binder on a support and at least one back layer on a side of the support opposite to the photosensitive layer. The back layer contains a compound which reacts with formic acid and a fluorine-containing surfactant having a specified structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３０】
式中、Ｒ^１は水素原子、塩素原子、アルキル基、またはアリール基を表し、Ｌ^１は−Ｃ（＝Ｏ）Ｎ（Ｒ^２）−、−Ｃ（＝Ｏ）Ｏ−、−Ｎ（Ｒ^２）Ｃ（＝Ｏ）−、−ＯＣ（＝Ｏ）−を表す。Ｒ^２は水素原子、アルキル基、アリール基、またはヘテロ環基を表す。Ｌ^２はＬ^１とＲ’を結ぶ二価の連結基を表し、ｉ、ｊはそれぞれ０または１を表す。Ｈ_２Ｎ−Ｒ’−は一般式（１）の化合物を構成するＲの水素原子を一個取り去った一価の基を表す。一般式（２）においてＲ^１は水素原子またはアルキル基が好ましく、水素原子または無置換の炭素数１〜４のアルキル基が更に好ましい。最も好ましくは水素原子またはメチル基である。Ｒ^２は水素原子、無置換のアルキル基または無置換のアリール基が好ましく、水素原子または無置換のアルキル基が更に好ましい。最も好ましくは水素原子である。一般式（２）において、Ｌ^２で表される二価の連結基とは−Ｏ−、−Ｓ−、−Ｎ（Ｒ_Ｎ）−、（Ｒ_Ｎは水素原子、アルキル基、アリール基を表す）、−Ｃ（＝Ｏ）−、−Ｃ（＝Ｓ）−、−ＳＯ_２−、−ＳＯ−、−Ｐ（＝Ｏ）−、アルキレン基、アリーレン基などの基の単独またはこれらの基の組み合わせからなる基である。ここで組み合わせからなる基を具体的に示せば−アリーレン基−アルキレン基−、−アルキレン基−Ｏ−アルキレン基−、−アリーレン基−Ｏ−アルキレン基−、−アルキレン基−Ｏ−アルキレン基−Ｏ−アルキレン基−Ｏ−アリーレン基−Ｏ−、−アリーレン基−Ｏ−、−アルキレン基−Ｎ（Ｒ_Ｎ）−、−アリーレン基−Ｎ（Ｒ_Ｎ）−、−アルキレン基−Ｃ（＝Ｏ）Ｏ−、−アリーレン基−Ｃ（＝Ｏ）Ｏ−、−アルキレン基−Ｃ（＝Ｏ）Ｎ（Ｒ_Ｎ）−、−アリーレン基−Ｃ（＝Ｏ）Ｎ（Ｒ_Ｎ）−などの基が挙げられる。なおこれらの基は左右どちらから連結されていても良い。一般式（２）において、好ましいＨ_２Ｎ−Ｒ’−は、上記一般式（１）の好ましい化合物例を構成するＲの水素原子を一個取り去った一価の基を挙げることができる。
【００３１】
次に一般式（１）で表される化合物、一般式（２）で表される単量体および合成したポリマーの組成の具体例を以下に示す。但し、ギ酸と反応する化合物として本発明で用いることができるものは、これらに限定されるものではない。
【００３２】
【化２】

【００３３】
【化３】

【００３４】
【化４】

【００３５】
【化５】

【００３６】
【化６】

【００３７】
一般式（１）で表される化合物等で代表される本発明に係るギ酸と反応する化合物は、水または適当な有機溶媒、例えばアルコール類（メタノール、エタノール、プロパノール、フッ素化アルコール）、ケトン類（アセトン、メチルエチルケトン）、ジメチルホルムアミド、ジメチルスルホキシド、メチルセルソルブなどに溶解して用いることができる。また、既に良く知られている乳化分散法によって、ジブチルフタレート、トリクレジルホスフェート、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して用いることができる。あるいは固体分散法として知られている方法によって、化合物の粉末を水などの適当な溶媒中にボールミル、コロイドミル、サンドグラインダーミル、マントンゴーリン、マイクロフルイダイザーあるいは超音波によって分散し用いることができる。
【００３８】
一般式（１）で表される化合物の添加量は、銀１モルに対し１×１０^−６〜１モルが好ましく、１×１０^−６〜５×１０^−１モルがより好ましく、２×１０^−６〜４×１０^−１モルが最も好ましい。また、一般式（１）で表される構造を部分構造として含むポリマーを用いる場合、その添加量は０．１ｍｇ／ｍ^２〜２ｇ／ｍ^２が好ましく、０．２ｍｇ／ｍ^２〜１ｇ／ｍ^２がより好ましく、０．２ｍｇ／ｍ^２〜０．５ｇ／ｍ^２が最も好ましい。これらは１種のみ用いても２種以上を併用してもよい。
【００３９】
〔一般式（Ｆ）で表される界面活性剤〕
次に、前記本発明に係るギ酸と反応する化合物と併用して用いられる一般式（Ｆ）で表される界面活性剤について説明する。
【００４０】
一般式（Ｆ） Ｘ−（Ｌ）ｍ−Ｒｆ−（Ｌ’）ｍ−Ｘ’
式中、Ｒｆは少なくとも１つのフッ素原子を有する脂肪族基を表す。脂肪族基としては炭素数が１〜１８であることが好ましく、さらに炭素数が２〜１２であることが好ましく、炭素数が３〜７であることが特に好ましい。Ｌ及びＬ’は単なる結合手又は２価の連結基を表す。２価の連結基としては、スルホンアミド基、アルキレンオキサイド基、フェノキシ基、アルキレンカルボニル基が特に好ましい。ｍは０または１〜５の整数を表す。Ｘ及びＸ’は水素原子、ヒドロキシル基、アニオン性基又はカチオン性基を表す。アニオン性基としては、カルボキシル基、スルホン酸基、リン酸基が好ましく、該アニオン性基のカウンターカチオンとしては、ナトリウムイオン、カリウムイオン、リチウムイオンなどのアルカリ金属イオン、アンモニウムイオンなどが好ましい。また、カチオン性基としては、４級アルキルアンモニウム基が好ましく、該カチオン性基のカウンターアニオンとしては、ハロゲン化物イオン、ｐ−トルエンスルホン酸イオンなどが好ましい。
【００４１】
以下に、一般式（Ｆ）で表される界面活性剤の好ましい具体例を例示するが、これらに限定されるものではない。
【００４２】
Ｆ−１ （ＯＮａ）_２ＯＰ−Ｏ−Ｃ_３Ｆ_６−Ｏ−ＰＯ（ＯＮａ）_２
Ｆ−２ ＮａＣＯＯ−Ｃ_３Ｆ_６−ＣＯＯＮａ
Ｆ−３ （ＣＯＯＮａ）_２ＣＨ−Ｏ−Ｃ_３Ｆ_６−Ｏ−ＣＨ（ＣＯＯＮａ）_２
Ｆ−４（ＣＯＯＮａ）_２ＣＨＣＯＮＨ−Ｃ_３Ｆ_６−ＮＨＣＯＣＨ（ＣＯＯＮａ）_２
Ｆ−５ ＫＯＯＣ−Ｃ_３Ｆ_６−ＣＯＯＫ
Ｆ−６ ＮａＯ_３Ｓ−Ｃ_３Ｆ_６−ＳＯ_３Ｎａ
Ｆ−７ ＮａＯ_３Ｓ−Ｏ−Ｃ_３Ｆ_６−Ｏ−ＳＯ_３Ｎａ
Ｆ−８ ＮａＯ_３Ｓ−Ｃ_３Ｈ_６Ｏ−Ｃ_３Ｆ_６−ＯＣ_３Ｈ_６−ＳＯ_３Ｎａ
Ｆ−９ ＬｉＯ_３Ｓ−Ｃ_３Ｆ_６−ＳＯ_３Ｌｉ
Ｆ−１０ ＬｉＯ_３Ｓ−Ｏ−Ｃ_３Ｆ_６−Ｏ−ＳＯ_３Ｌｉ
Ｆ−１１ ＬｉＯ_３Ｓ−Ｃ_３Ｈ_６Ｏ−Ｃ_３Ｆ_６−ＯＣ_３Ｈ_６−ＳＯ_３Ｌｉ
Ｆ−１２ ＨＯ−Ｃ_３Ｆ_６−ＯＨ
Ｆ−１３ ＨＯ−Ｃ_３Ｈ_６Ｏ−Ｃ_４Ｆ_９−ＯＣ_３Ｈ_６−ＯＨ
Ｆ−１４ （Ｃ_２Ｈ_４ＯＨ）_３−Ｏ−ＨＣ_４Ｆ_８−Ｏ−Ｃ（Ｃ_２Ｈ_４ＯＨ）_３
Ｆ−１５ ＨＯ−（ＣＦ_３）_２Ｃ−ＯＨ
一般式（Ｆ）で表される界面活性剤の合成方法については、特表平１０−５００９５０号公報、同１１−５０４３６０号公報を参考にすることが出来る。
【００４３】
一般式（Ｆ）で表される界面活性剤をバック層に含有させるには、バック層を構成する非感光層のどの層に添加しても良く、メタノール等の有機溶媒に一度溶解し塗布液に添加しても良い。
【００４４】
一般式（Ｆ）で表される界面活性剤の添加量は、２０〜２００ｍｇ／ｍ^２が好ましく、特に好ましくは５０〜１５０ｍｇ／ｍ^２である。
【００４５】
次に、本発明の熱現像感光材料に一般的に用いることのできる、非感光性有機銀塩、感光性ハロゲン化銀、還元剤、硬調化剤、バインダー、支持体等について説明する。
【００４６】
〔非感光性有機銀塩〕
本発明に係る感光層には還元可能な銀源である非感光性有機銀塩（以下、単に有機銀塩ともいう）を含有しており、有機銀塩としては還元可能な銀イオン源を含有する有機酸及びヘテロ有機酸の銀塩、特に長鎖（１０〜３０、好ましくは５〜２５の炭素原子数）の脂肪族カルボン酸及び含窒素複素環カルボン酸が好ましい。配位子が、４．０〜１０．０の銀イオンに対する総安定定数を有する有機又は無機の銀塩錯体も有用である。好適な銀塩の例は、Ｒｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ第１７０２９及び２９９６３に記載されており、次のものがある。例えば、有機酸の塩（例えば、没食子酸、シュウ酸、ベヘン酸、ステアリン酸、パルミチン酸、ラウリン酸等の塩）；銀のカルボキシアルキルチオ尿素塩（例えば、１−（３−カルボキシプロピル）チオ尿素、１−（３−カルボキシプロピル）−３，３−ジメチルチオ尿素等）；アルデヒドとヒドロキシ置換芳香族カルボン酸とのポリマー反応生成物の銀錯体（例えば、ホルムアルデヒド、アセトアルデヒド、ブチルアルデヒドのようなアルデヒド類とサリチル酸、ベンジル酸３，５−ジヒドロキシ安息香酸、５，５−チオジサリチル酸のようなヒドロキシ置換酸類）；チオン類の銀塩又は錯体（例えば、３−（２−カルボキシエチル）−４−ヒドロキシメチル−４−チアゾリン−２−チオン及び３−カルボキシメチル−４−メチル−４−チアゾリン−２−チオン）；イミダゾール、ピラゾール、ウラゾール、１，２，４−チアゾール及び１Ｈ−テトラゾール、３−アミノ−５−ベンジルチオ−１，２，４−トリアゾール及びベンゾトリアゾールから選択される窒素酸と銀との錯体または塩；サッカリン、５−クロロサリチルアルドキシム等の銀塩；メルカプチド類の銀塩等が挙げられる。好ましい銀源はベヘン酸銀、アラキジン酸銀および／またはステアリン酸銀である。
【００４７】
有機銀塩は、水溶性銀化合物と銀と錯形成する化合物を混合することにより得られるが、正混合法、逆混合法、同時混合法、特開平９−１２７６４３号公報に記載されている様なコントロールドダブルジェット法等が好ましく用いられる。例えば、有機酸にアルカリ金属塩（例えば、水酸化ナトリウム、水酸化カリウムなど）を加えて有機酸アルカリ金属塩ソープ（例えば、ベヘン酸ナトリウム、アラキジン酸ナトリウムなど）を作製した後に、コントロールドダブルジェットにより、前記ソープと硝酸銀などを添加して有機銀塩の結晶を作製する。その際にハロゲン化銀粒子を混在させてもよい。
【００４８】
本発明に係る有機銀塩は、平均粒径が１μｍ以下でありかつ単分散であることが好ましい。有機銀塩の平均粒径とは、有機銀塩の粒子が例えば球状、棒状、或いは平板状の粒子の場合には、有機銀塩粒子の体積と同等な球を考えたときの直径をいう。平均粒径は好ましくは０．０１μｍ〜０．８μｍ、特に０．０５μｍ〜０．５μｍが好ましい。また単分散とは、ハロゲン化銀の場合と同義であり、好ましくは単分散度が１〜３０である。本発明においては、有機銀塩が平均粒径１μｍ以下の単分散粒子であることがより好ましく、この範囲にすることで濃度の高い画像が得られる。さらに有機銀塩は平板状粒子が全有機銀の６０％以上有することが好ましい。本発明において平板状粒子とは平均粒径と厚さの比、いわゆる下記式で表されるアスペクト比（ＡＲと略す）が３以上のものをいう。
【００４９】
ＡＲ＝平均粒径（μｍ）／厚さ（μｍ）
このような有機銀塩粒子は必要に応じバインダーや界面活性剤などと共に予備分散した後、メディア分散機または高圧ホモジナイザなどで分散粉砕することが好ましい。上記予備分散にはアンカー型、プロペラ型等の一般的攪拌機や高速回転遠心放射型攪拌機（ディゾルバ）、高速回転剪断型撹拌機（ホモミキサ）を使用することができる。また、上記メディア分散機としては、ボールミル、遊星ボールミル、振動ボールミルなどの転動ミルや、媒体攪拌ミルであるビーズミル、アトライター、その他バスケットミルなどを用いることが可能であり、高圧ホモジナイザとしては壁、プラグなどに衝突するタイプ、液を複数に分けてから高速で液同士を衝突させるタイプ、細いオリフィスを通過させるタイプなど様々なタイプを用いることができる。
【００５０】
本発明に係る有機銀塩粒子を分散する際に用いられる装置類において、該有機銀粒子が接触する部材の材質としてジルコニア、アルミナ、窒化珪素、窒化ホウ素などのセラミックス類またはダイヤモンドを用いることが好ましく、特にジルコニアを用いることが好ましい。
【００５１】
本発明に係る有機銀塩粒子は銀１ｇあたり０．０１ｍｇ〜０．５ｍｇのジルコニウムを含有することが好ましく、特に好ましくは０．０１ｍｇ〜０．３ｍｇのジルコニウムを含有する場合である。上記分散をおこなう際の、バインダー濃度、予備分散方法、分散機運転条件、分散回数などを最適化することは、本発明に用いられる有機銀塩粒子を得る方法として非常に好ましい。
【００５２】
〔感光性ハロゲン化銀〕
本発明に係る感光層に含有される感光性ハロゲン化銀は、光センサーとして機能するものである。本発明においては、画像形成後の白濁を低く抑えるため、及び良好な画質を得るために、感光性ハロゲン化銀の粒子は、平均粒子サイズが小さい方が好ましい。平均粒子サイズが、好ましくは０．０３μｍ以下、より好ましくは０．０１〜０．０３μｍの範囲である。
【００５３】
本発明の熱現像感光材料に用いる感光性ハロゲン化銀粒子は、前記有機銀塩調製時に同時に作製されるか、または前記有機銀塩調製時に該ハロゲン化銀粒子を混在させて調製することにより、有機銀塩に融着した状態でハロゲン化銀粒子を形成させて微小粒子のいわゆるｉｎ ｓｉｔｕ銀とするのが好ましい。
【００５４】
上記ハロゲン化銀粒子の平均粒子径の測定方法は、電子顕微鏡により５００００倍で撮影し、それぞれのハロゲン化銀粒子の長辺と短辺を実測し、１００個の粒子を測定し、平均したものを平均粒径とする。ここで、上記粒子サイズとは、ハロゲン化銀粒子が立方体或いは八面体のいわゆる正常晶である場合には、ハロゲン化銀粒子の稜の長さをいう。又、正常晶でない場合、例えば、球状、棒状、或いは平板状の粒子の場合には、ハロゲン化銀粒子の体積と同等な球を考えたときの直径をいう。またハロゲン化銀粒子は単分散であることが好ましい。ここでいう単分散とは、下記式で求められる単分散度が４０％以下をいう。更に好ましくは３０％以下であり、特に好ましくは０．１〜２０％となる粒子である。
【００５５】
単分散度＝（粒径の標準偏差）／（粒径の平均値）×１００
本発明に係る感光性ハロゲン化銀粒子は平均粒径０．０１〜０．０３μｍで、かつ単分散粒子であることがより好ましく、この範囲にすることで画像の粒状性も向上する。ハロゲン化銀粒子の形状については、特に制限はないが、ミラー指数〔１００〕面の占める割合が高いことが好ましく、この割合が５０％以上、更には７０％以上、特に８０％以上であることが好ましい。ミラー指数〔１００〕面の比率は、増感色素の吸着における〔１１１〕面と〔１００〕面との吸着依存性を利用したＴ．Ｔａｎｉ；Ｊ．Ｉｍａｇｉｎｇ Ｓｃｉ．，２９，１６５（１９８５）により求めることができる。
【００５６】
又、もう一つの好ましい感光性ハロゲン化銀粒子の形状は、平板粒子である。平板粒子とは、投影面積の平方根を粒径ｒμｍとして、垂直方向の厚みをｈμｍとした場合のアスペクト比＝ｒ／ｈが３以上のものをいう。その中でもアスペクト比が３〜５０が好ましい。また粒径は０．０３μｍ以下であることが好ましく、さらに０．０１〜０．０３μｍが好ましい。これらの製法は米国特許第５，２６４，３３７号、同５，３１４，７９８号、同５，３２０，９５８号等の各明細書に記載されており、容易に目的の平板状粒子を得ることができる。本発明においてこれらの平板状粒子を用いた場合、さらに画像の鮮鋭性も向上する。
【００５７】
感光性ハロゲン化銀粒子の組成としては特に制限はなく、塩化銀、塩臭化銀、塩沃臭化銀、臭化銀、沃臭化銀、沃化銀のいずれであってもよい。本発明に用いられる写真乳剤は、Ｐ．Ｇｌａｆｋｉｄｅｓ著Ｃｈｉｍｉｅ ｅｔ Ｐｈｙｓｉｑｕｅ Ｐｈｏｔｏｇｒａｐｈｉｑｕｅ（Ｐａｕｌ Ｍｏｎｔｅｌ社刊、１９６７年）、Ｇ．Ｆ．Ｄｕｆｆｉｎ著 Ｐｈｏｔｏｇｒａｐｈｉｃ Ｅｍｕｌｓｉｏｎ Ｃｈｅｍｉｓｔｒｙ（Ｔｈｅ Ｆｏｃａｌ Ｐｒｅｓｓ刊、１９６６年）、Ｖ．Ｌ．Ｚｅｌｉｋｍａｎ ｅｔ ａｌ著Ｍａｋｉｎｇ ａｎｄ Ｃｏａｔｉｎｇ Ｐｈｏｔｏｇｒａｐｈｉｃ Ｅｍｕｌｓｉｏｎ（Ｔｈｅ Ｆｏｃａｌ Ｐｒｅｓｓ刊、１９６４年）等に記載された方法を用いて調製することができる。
【００５８】
本発明に係る感光性ハロゲン化銀粒子には、照度不軌改良や改良調整のために、元素周期律表の６族から１０族に属する金属のイオン又は錯体イオンを含有することが好ましい。上記の金属としては、Ｗ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｒｕ、Ｒｈ、Ｐｄ、Ｒｅ、Ｏｓ、Ｉｒ、Ｐｔ、Ａｕが好ましい。
【００５９】
感光性ハロゲン化銀粒子は、ヌードル法、フロキュレーション法等、当業界で知られている方法の水洗により脱塩することができるが、本発明においては脱塩してもしなくてもよい。
【００６０】
本発明に係る感光性ハロゲン化銀粒子は、化学増感されていることが好ましい。好ましい化学増感法としては、当業界でよく知られているように硫黄増感法、セレン増感法、テルル増感法、金化合物や白金、パラジウム、イリジウム化合物等の貴金属増感法や還元増感法を用いることができる。
【００６１】
本発明に係る感光性ハロゲン化銀粒子及び有機銀塩の総量は、熱現像感光材料の失透を防ぐために、銀量に換算して１ｍ^２当たり０．３〜２．２ｇが好ましく、０．５ｇ〜１．５ｇがより好ましい。この範囲にすることで、硬調な画像が得られる。また銀総量に対するハロゲン化銀の量は、質量比で５０％以下、好ましくは２５％以下、更に好ましくは０．１〜１５％の間である。
【００６２】
本発明に係る感光性ハロゲン化銀粒子は３５０〜４５０μｍに光の極大吸収を有し、特に増感色素を有してなくてもよいが、必要に応じて含有させてもよい。
【００６３】
〔還元剤〕
本発明に係る還元剤は、米国特許第３，７７０，４４８号、同３，７７３，５１２号、同３，５９３，８６３号等の各明細書及びＲｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ第１７０２９及び第２９９６３等に記載されているものを使うことができる。例えば、次のものが挙げられる。
【００６４】
アミノヒドロキシシクロアルケノン化合物（例えば、２−ヒドロキシ−３−ピペリジノ−２−シクロヘキセノン）；還元剤の前駆体としてアミノレダクトン類（ｒｅｄｕｃｔｏｎｅｓ）エステル（例えば、ピペリジノヘキソースレダクトンモノアセテート）；Ｎ−ヒドロキシ尿素誘導体（例えば、Ｎ−ｐ−メチルフェニル−Ｎ−ヒドロキシ尿素）；アルデヒド又はケトンのヒドラゾン類（例えば、アントラセンアルデヒドフェニルヒドラゾン）；ホスファーアミドフェノール類；ホスファーアミドアニリン類；ポリヒドロキシベンゼン類（例えば、ヒドロキノン、ｔ−ブチル−ヒドロキノン、イソプロピルヒドロキノン及び（２，５−ジヒドロキシ−フェニル）メチルスルホン）；スルフヒドロキサム酸類（例えば、ベンゼンスルフヒドロキサム酸）；スルホンアミドアニリン類（例えば、４−（Ｎ−メタンスルホンアミド）アニリン）；２−テトラゾリルチオヒドロキノン類（例えば、２−メチル−５−（１−フェニル−５−テトラゾリルチオ）ヒドロキノン）；テトラヒドロキノキサリン類（例えば、１，２，３，４−テトラヒドロキノキサリン）；アミドオキシム類；アジン類；脂肪族カルボン酸アリールヒドラザイド類とアスコルビン酸の組み合わせ；ポリヒドロキシベンゼンとヒドロキシルアミンの組み合わせ；レダクトン及び／又はヒドラジン；ヒドロキサン酸類；アジン類とスルホンアミドフェノール類の組み合わせ；α−シアノフェニル酢酸誘導体；ビス−β−ナフトールと１，３−ジヒドロキシベンゼン誘導体の組み合わせ；５−ピラゾロン類；スルホンアミドフェノール還元剤；２−フェニルインダン−１，３−ジオン等；クロマン；１，４−ジヒドロピリジン類（例えば、２，６−ジメトキシ−３，５−ジカルボエトキシ−１，４−ジヒドロピリジン）；ビスフェノール類（例えば、ビス（２−ヒドロキシ−３−ｔ−ブチル−５−メチルフェニル）メタン、ビス（６−ヒドロキシ−ｍ−トリ）メシトール（ｍｅｓｉｔｏｌ）、２，２−ビス（４−ヒドロキシ−３−メチルフェニル）プロパン、４，４−エチリデン−ビス（２−ｔ−ブチル−６−メチルフェノール））、紫外線感応性アスコルビン酸誘導体；ヒンダードフェノール類；３−ピラゾリドン類。中でも特に好ましい還元剤は、ヒンダードフェノール類である。ヒンダードフェノール類としては、下記一般式（Ａ）で表される化合物が挙げられる。
【００６５】
【化７】

【００６６】
式中、Ｒは水素原子、又は炭素原子数１〜１０のアルキル基（例えば、−Ｃ４Ｈ９、２，４，４−トリメチルペンチル）を表し、Ｒ′及びＲ″は炭素原子数１〜５のアルキル基（例えば、メチル、エチル、ｔ−ブチル）を表す。
【００６７】
一般式（Ａ）で表される化合物の具体例を以下に示す。ただし、本発明は、以下の化合物に限定されるものではない。
【００６８】
【化８】

【００６９】
【化９】

【００７０】
前記一般式（Ａ）で表される化合物を始めとする還元剤の使用量は、好ましくは銀１モル当り１×１０^−２〜１０モル、特に１×１０^−２〜１．５モルである。この量の範囲内において、上述した還元剤は少なくとも２種併用されてもよい。
【００７１】
〔硬調化剤〕
本発明に係る硬調化剤としては、ヒドラジン化合物があり、例えば、Ｒｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ Ｉｔｅｍ ２３５１５（１９８３年１１月号、Ｐ．３４６）及びそこに引用された文献の他、米国特許第４，０８０，２０７号、同第４，２６９，９２９号、同第４，２７６，３６４号、同第４，２７８，７４８号、同第４，３８５，１０８号、同第４，４５９，３４７号、同第４，４７８，９２８号、同第４，５６０，６３８号、同第４，６８６，１６７号、同第４，９１２，０１６号、同第４，９８８，６０４号、同第４，９９４，３６５号、同第５，０４１，３５５号、同第５，１０４，７６９号、英国特許第２，０１１，３９１Ｂ号、欧州特許第２１７，３１０号、同第３０１，７９９号、同第３５６，８９８号、特開昭６０−１７９７３４号、同６１−１７０７３３号、同６１−２７０７４４号、同６２−１７８２４６号、同６２−２７０９４８号、同６３−２９７５１号、同６３−３２５３８号、同６３−１０４０４７号、同６３−１２１８３８号、同６３−１２９３３７号、同６３−２２３７４４号、同６３−２３４２４４号、同６３−２３４２４５号、同６３−２３４２４６号、同６３−２９４５５２号、同６３−３０６４３８号、同６４−１０２３３号、特開平１−９０４３９号、同１−１００５３０号、同１−１０５９４１号、同１−１０５９４３号、同１−２７６１２８号、同１−２８０７４７号、同１−２８３５４８号、同１−２８３５４９号、同１−２８５９４０号、同２−２５４１号、同２−７７０５７号、同２−１３９５３８号、同２−１９６２３４号、同２−１９６２３５号、同２−１９８４４０号、同２−１９８４４１号、同２−１９８４４２号、同２−２２００４２号、同２−２２１９５３号、同２−２２１９５４号、同２−２８５３４２号、同２−２８５３４３号、同２−２８９８４３号、同２−３０２７５０号、同２−３０４５５０号、同３−３７６４２号、同３−５４５４９号、同３−１２５１３４号、同３−１８４０３９号、同３−２４００３６号、同３−２４００３７号、同３−２５９２４０号、同３−２８００３８号、同３−２８２５３６号、同４−５１１４３号、同４−５６８４２号、同４−８４１３４号、同２−２３０２３３号、同４−９６０５３号、同４−２１６５４４号、同５−４５７６１号、同５−４５７６２号、同５−４５７６３号、同５−４５７６４号、同５−４５７６５号、同６−２８９５２４号、同９−１６０１６４号等の各公報ないしは明細書に記載されたものを挙げることができる。
【００７２】
この他にも、特公平６−７７１３８号公報に記載の（化１）で表される化合物で、具体的には同公報３頁、４頁に記載された化合物、特公平６−９３０８２号公報に記載された一般式（１）で表される化合物で具体的には同公報８頁〜１８頁に記載の１〜３８の化合物、特開平６−２３０４９号公報に記載の一般式（４）、（５）及び（６）で表される化合物で、具体的には同公報２５頁、２６頁に記載の化合物４−１〜４−１０、２８頁〜３６頁に記載の化合物５−１〜５−４２、及び３９頁、４０頁に記載の化合物６−１〜６−７、特開平６−２８９５２０号公報に記載の一般式（１）及び（２）で表される化合物で、具体的には同公報５頁から７頁に記載の化合物１−１）〜１−１７）及び２−１）、特開平６−３１３９３６号公報に記載の（化２）及び（化３）で表される化合物で具体的には同公報６頁から１９頁に記載の化合物、特開平６−３１３９５１号公報に記載の（化１）で表される化合物で、具体的には同公報３頁から５頁に記載された化合物、特開平７−５６１０号公報に記載の一般式（Ｉ）で表される化合物で、具体的には同公報の５頁から１０頁に記載の化合物Ｉ−１〜Ｉ−３８、特開平７−７７７８３号公報に記載の一般式（ＩＩ）で表される化合物で、具体的には同公報１０頁〜２７頁に記載の化合物ＩＩ−１〜ＩＩ−１０２、特開平７−１０４４２６号公報に記載の一般式（Ｈ）及び一般式（Ｈａ）で表される化合物で、具体的には同公報８頁〜１５頁に記載の化合物Ｈ−１〜Ｈ−４４に記載されたもの等を用いることができる。
【００７３】
さらにその他の硬調化剤としては特開平１１−３１６４３７号公報の３３頁から５３頁に記載の化合物であり、さらに好ましくは特開平１２−２９８３２７号公報の２１頁から１４頁に記載の下記化合物である。
【００７４】
【化１０】

【００７５】
【化１１】

【００７６】
【化１２】

【００７７】
【化１３】

【００７８】
〔バインダー〕
本発明に係る感光層には、有機銀塩、感光性ハロゲン化銀、還元剤等を保持するためにバインダーが用いられている。バインダーは透明又は半透明で、一般に無色であり、天然ポリマーや合成モノ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、アラビアゴム、ポリ（ビニルアルコール）、ヒドロキシエチルセルロース、セルロースアセテート、セルロースアセテートブチレート、ポリ（ビニルピロリドン）、カゼイン、デンプン、ポリ（アクリル酸）、ポリ（メチルメタクリル酸）、ポリ（塩化ビニル）、ポリ（メタクリル酸）、コポリ（スチレン−無水マレイン酸）、コポリ（スチレン−アクリロニトリル）、コポリ（スチレン−ブタジエン）、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）、ポリ（エポキシド）類、ポリ（カーボネート）類、ポリ（ビニルアセテート）、セルロースエステル類、ポリ（アミド）類がある。本発明の熱現像感光材料に用いられるバインダーは、親水性バインダーでも、疎水性バインダーでもよいが、熱現像後のカブリを低減させるために、疎水性透明バインダーを使用することが好ましい。
【００７９】
好ましいバインダーとしては、ポリビニルブチラール、セルロースアセテート、セルロースアセテートブチレート、ポリエステル、ポリカーボネート、ポリアクリル酸、ポリウレタンなどがあげられる。その中でもポリビニルブチラール、セルロースアセテート、セルロースアセテートブチレート、ポリエステルが特に好ましく用いられる。上記のように疎水性透明バインダーを使用することが好ましいが、必要により、水可溶性樹脂又は水分散系樹脂（ラテックス）を適量併用することができる。
【００８０】
上記疎水性透明バインダーを溶解または分散するための主溶媒としては、有機溶媒が主として用いられ、例えばアルコール類（メタノール、エタノール、プロパノール）、ケトン類（アセトン、メチルエチルケトン）ジメチルホルムアミド、ジメチルスルホキシド、メチルセルソルブ等が好ましく用いられ、必要に応じて、好ましくは２０質量％以下、さらに好ましくは１０質量％以下、さらに好ましくは５質量％以下の水が含有されてもよい。
【００８１】
感光層のバインダーの含有量は熱現像の速度を速めるために１．５〜１０ｇ／ｍ^２であることが好ましい。さらに好ましくは１．７〜８ｇ／ｍ^２である。１．５ｇ／ｍ^２未満ではバインダー樹脂の種類によっては未露光部の濃度が大幅に上昇し、使用に耐えない場合がある。１０ｇ／ｍ^２を越えた場合は、バインダーの種類によっては現像性が低下して濃度が出ない場合がある。
【００８２】
これらバインダーは、感光層の表面を保護したり擦り傷を防止するために、感光層の上部に積層された保護層、感光層とは反対の面には搬送性確保や、保護層とのブロッキング防止のためにバック層とバック保護層にも使用することが出来る。
【００８３】
これらの非感光層である保護層、バック層、バック保護層に用いられるバインダーは感光層に用いられるバインダーと同じ種類でも異なった種類でもよい。尚、非感光層には、活性エネルギー線で硬化可能なエポキシ樹脂やアクリルモノマーなどを層形成バインダーとして使用しても良い。
【００８４】
〔支持体〕
本発明の熱現像感光材料に用いられる支持体としては、現像処理後に所定の光学濃度を得るため及び現像処理後の画像の変形を防ぐために、プラスチックフィルム（例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリカーボネート、ポリイミド、ナイロン、セルローストリアセテート、ポリエチレンナフタレート）であることが好ましい。その中でも好ましい支持体としては、ポリエチレンテレフタレート及びシンジオタクチック構造を有するスチレン系重合体を含むプラスチックの支持体が挙げられる。支持体の厚みとしては５０〜３００μｍ程度、好ましくは７０〜１８０μｍである。
【００８５】
また、熱処理したプラスチック支持体を用いることもできる。採用するプラスチックとしては、前記のプラスチックが挙げられる。支持体の熱処理とはこれらの支持体を製膜後、感光層、保護層が塗布されるまでの間に、支持体のガラス転移点より３０℃以上高い温度で、好ましくは３５℃以上高い温度で、更に好ましくは４０℃以上高い温度で加熱することがよい。但し、支持体の融点を超えた温度に加熱することは支持体の強度の均一性を損い、好ましくない。
【００８６】
〔その他の素材〕
本発明の熱現像感光材料は、熱現像感光材料のすべり性や指紋付着防止のため、感光層又は保護層にマット剤を含有することが好ましい。マット剤の含有量は使用している全バインダーに対し、質量比で０．５〜３０％含有することが好ましい。また、支持体を挟み感光層の反対側の非感光層のバック層、バック保護層の少なくとも１層中にマット剤を含有することが好ましい。バック層、バック保護層の全バインダーに対し、質量比で０．５〜４０％含有することが好ましい。
【００８７】
マット剤としては、下記に示す物性を満たすのであれば、定形、不定形を問わず如何なるものでも使用できる。例えば、不定形シリカ、窒化ホウ素、窒化アルミニウム、二酸化チタン、酸化マグネシウム、酸化アルミニウム、酸化カルシウム、ハイドロキシアパタイト、炭酸マグネシウム、硫酸バリウム、硫酸ストロンチウム、ポリメチルメタクリレート、ポリメチルアクリレート、ポリスチレン、ポリアクリロニトリル、セルロースアセテート、セルロースプロピオネート、シリコーン、テフロン（Ｒ）等がある。また、微粒子に滑り性を与えるためワックスやシリコーンオイルを染み込ませたものや、シランカップリング剤やチタンカップリング剤を用いて表面を修飾したものも使用できる。マット剤の大きさはマット剤の体積を球形に換算したときの直径で表される。本発明において、マット剤の粒径とはこの球形換算した直径のことを示すものとする。
【００８８】
感光層側のマット剤の平均粒径は０．５μｍ〜１０μｍであることが好ましく、更に好ましくは１．０μｍ〜８μｍである。バック層、バック保護層に使用するマット剤の平均粒径は３．０μｍ〜２０μｍであることが好ましく、更に好ましくは４．０〜１５μｍである。
【００８９】
本発明の熱現像感光材料は、感光層に必要に応じてカブリ防止剤、調色剤、増感色素、強色増感を示す物質（以下強色増感剤と略記する）など各種添加剤を添加してもよい。
【００９０】
このような、カブリ防止剤としては、米国特許第３，８７４，９４６号明細書及び同第４，７５６，９９９号明細書に開示されているような化合物、−Ｃ（Ｘ_１）（Ｘ_２）（Ｘ_３）（ここでＸ_１及びＸ_２はハロゲン原子を表し、Ｘ_３は水素またはハロゲン原子を表す）で表される置換基を少なくとも１つ備えたヘテロ環状化合物、特開平９−２８８３２８号公報、特開平９−９０５５０号公報、米国特許第５，０２８，５２３号明細書及び欧州特許第６００，５８７号、同第６０５，９８１号、同第６３１，１７６号の各明細書に開示されている化合物を適時選択して用いることが出来る。
【００９１】
現像後の銀色調を改良する目的で、感光層に添加される色調剤としてはイミド類（例えば、フタルイミド）；環状イミド類、ピラゾリン−５−オン類、及びキナゾリノン（例えば、スクシンイミド、３−フェニル−２−ピラゾリン−５−オン、１−フェニルウラゾール、キナゾリン及び２，４−チアゾリジンジオン）；ナフタールイミド類（例えば、Ｎ−ヒドロキシ−１，８−ナフタールイミド）；コバルト錯体（例えば、コバルトのヘキサミントリフルオロアセテート）、メルカプタン類（例えば、３−メルカプト−１，２，４−トリアゾール）；Ｎ−（アミノメチル）アリールジカルボキシイミド類（例えば、Ｎ−（ジメチルアミノメチル）フタルイミド）；ブロックされたピラゾール類、イソチウロニウム（ｉｓｏｔｈｉｕｒｏｎｉｕｍ）誘導体及びある種の光漂白剤の組み合わせ（例えば、Ｎ，Ｎ′−ヘキサメチレン（１−カルバモイル−３，５−ジメチルピラゾール）、１，８−（３，６−ジオキサオクタン）ビス（イソチウロニウムトリフルオロアセテート）、及び２−（トリブロモメチルスルホニル）ベンゾチアゾールの組み合わせ）；メロシアニン染料（例えば、３−エチル−５−（（３−エチル−２−ベンゾチアゾリニリデン（ベンゾチアゾリニリデン））−１−メチルエチリデン）−２−チオ−２，４−オキサゾリジンジオン）；フタラジノン、フタラジノン誘導体またはこれらの誘導体の金属塩（例えば、４−（１−ナフチル）フタラジノン、６−クロロフタラジノン、５，７−ジメチルオキシフタラジノン、及び２，３−ジヒドロ−１，４−フタラジンジオン）；フタラジノンとスルフィン酸誘導体の組み合わせ（例えば、６−クロロフタラジノン＋ベンゼンスルフィン酸ナトリウムまたは８−メチルフタラジノン＋ｐ−トリスルホン酸ナトリウム）；フタラジン＋フタル酸の組み合わせ；フタラジン（フタラジンの付加物を含む）とマレイン酸無水物、及びフタル酸、２，３−ナフタレンジカルボン酸またはｏ−フェニレン酸誘導体及びその無水物（例えば、フタル酸、４−メチルフタル酸、４−ニトロフタル酸及びテトラクロロフタル酸無水物）から選択される少なくとも１つの化合物との組み合わせ；キナゾリンジオン類、ベンズオキサジン、ナルトキサジン誘導体；ベンズオキサジン−２，４−ジオン類（例えば、１，３−ベンズオキサジン−２，４−ジオン）；ピリミジン類及び不斉−トリアジン類（例えば、２，４−ジヒドロキシピリミジン）、及びテトラアザペンタレン誘導体（例えば、３，６−ジメルカプト−１，４−ジフェニル−１Ｈ，４Ｈ−２，３ａ，５，６ａ−テトラアザペンタレン）。好ましい色調剤としては、フタラゾン、フタラジンが挙げられる。色調剤は本発明の目的を阻害しないのであれば保護層に添加しても良い。
【００９２】
増感色素としては、例えばアルゴンイオンレーザー光源に対しは、特開昭６０−１６２２４７号公報、特開平２−４８６３５号公報、米国特許第２，１６１，３３１号明細書、西独特許第９３６，０７１号明細書、特開平５−１１３８９号公報等に記載のシンプルメロシアニン類、ヘリウムネオンレーザー光源に対しては、特開昭５０−６２４２５号、同５４−１８７２６号、同５９−１０２２２９号の各公報に示された三核シアニン色素類、特開平７−２８７３３８号公報に記載されたメロシアニン類、ＬＥＤ光源及び赤外半導体レーザー光源に対しては特公昭４８−４２１７２号、同５１−９６０９号、同５５−３９８１８号、特開昭６２−２８４３４３号、特開平２−１０５１３５号の各公報に記載されたチアカルボシアニン類、赤外半導体レーザー光源に対しては特開昭５９−１９１０３２号、特開昭６０−８０８４１号の各公報に記載されたトリカルボシアニン類、特開昭５９−１９２２４２号、特開平３−６７２４２号の各公報に記載の一般式（ＩＩＩａ）、（ＩＩＩｂ）に記載された４−キノリン核を含有するジカルボシアニン類等が有利に選択される。更に赤外レーザー光源の波長が７５０ｎｍ以上更に好ましくは８００ｎｍ以上である場合このような波長域のレーザーに対応する為には、特開平４−１８２６３９号、同５−３４１４３２号、特公平６−５２３８７号、同３−１０９３１号の各公報、米国特許第５，４４１，８６６号明細書、特開平７−１３２９５号公報に記載されている増感色素が好ましく用いられる。
【００９３】
強色増感剤としてはＲＤ１７６４３、特公平９−２５５００号、同４３−４９３３号、特開昭５９−１９０３２号、同５９−１９２２４２号、特開平５−３４１４３２号等の各公報に記載されている化合物を適時選択して用いることができる。
【００９４】
本発明では、下記一般式（Ｍ）で表される複素芳香族メルカプト化合物、実質的に前記のメルカプト化合物を生成する一般式（Ｍａ）で表されるジスルフィド化合物を用いることができる。
【００９５】
一般式（Ｍ） Ａｒ−ＳＭ
一般式（Ｍａ） Ａｒ−Ｓ−Ｓ−Ａｒ
一般式（Ｍ）中、Ｍは水素原子またはアルカリ金属原子を表し、Ａｒは少なくとも１個の窒素、硫黄、酸素、セレニウムもしくはテルリウム原子を有する複素芳香環または縮合複素芳香環を表す。複素芳香環は、好ましくは、ベンズイミダゾール、ナフトイミダゾール、ベンゾチアゾール、ナフトチアゾール、ベンズオキサゾール、ナフトオキサゾール、ベンゾセレナゾール、ベンゾテルラゾール、イミダゾール、オキサゾール、ピラゾール、トリアゾール、トリアジン、ピリミジン、ピリダジン、ピラジン、ピリジン、プリン、キノリンまたはキナゾリンである。また、一般式（Ｍａ）中のＡｒは上記一般式（Ｍ）の場合と同義である。
【００９６】
上記の複素芳香環は、例えば、ハロゲン原子（例えば、Ｃｌ、Ｂｒ、Ｉ）、ヒドロキシ基、アミノ基、カルボキシル基、アルキル基（例えば、１個以上の炭素原子、好ましくは、１〜４個の炭素原子を有するもの）及びアルコキシ基（例えば、１個以上の炭素原子、好ましくは、１〜４個の炭素原子を有するもの）からなる群から選ばれる置換基を有することができる。
【００９７】
高感度にするためには強色増感剤として下記に示す有機硫黄化合物を用いることがより好ましい。
【００９８】
【化１４】

【００９９】
【化１５】

【０１００】
本発明に係る強色増感剤は有機銀塩及びハロゲン化銀粒子を含む感光層の乳剤層中に銀１モル当たり０．００１〜１．０モルの範囲で用いるのが好ましく、特に銀１モル当たり０．０１〜０．５モルの範囲にするのが好ましい。
【０１０１】
本発明に係る感光層にはヘテロ原子を含む大環状化合物を含有させることができる。ヘテロ原子として窒素原子、酸素原子、硫黄原子及びセレン原子の少なくとも１種を含む９員環以上の大環状化合物が好ましく、１２〜２４員環がより好ましく、更に好ましいのは１５〜２１員環である。代表的な化合物としては、クラウンエーテルで下記のＰｅｄｅｒｓｏｎが１９６７年に合成し、その特異な報告以来、数多く合成されているものである。これらの化合物は、Ｃ．Ｊ．Ｐｅｄｅｒｓｏｎ，Ｊｏｕｒｎａｌ ｏｆ Ａｍｅｒｉｃａｎ ｃｈｅｍｉｃａｌ ｓｏｃｉｅｔｙ ｖｏｌ，８６（２４９５），７０１７〜７０３６（１９６７），Ｇ．Ｗ．Ｇｏｋｅｌ，Ｓ．Ｈ，Ｋｏｒｚｅｎｉｏｗｓｋｉ，”Ｍａｃｒｏｃｙｃｌｉｃ ｐｏｌｙｅｔｈｒ ｓｙｎｔｈｅｓｉｓ”，Ｓｐｒｉｎｇｅｒ−Ｖｅｒｇａｌ，（１９８２）等に記載されている。
【０１０２】
本発明に係る感光層には上述した添加剤以外に例えば、界面活性剤、酸化防止剤、安定化剤、可塑剤、紫外線吸収剤、被覆助剤等を用いても良い。これらの添加剤及び上述したその他の添加剤はＲｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ Ｉｔｅｍ１７０２９（１９７８年６月ｐ．９〜１５）に記載されている化合物が好ましく用いられる。
【０１０３】
本発明においては帯電性を改良するために金属酸化物および／または導電性ポリマーなどの導電性化合物を、下引層、バック層、感光層と下引層の間の中間層など構成層中に含ませることができる。
【０１０４】
本発明に係る感光層の上部に積層される保護層は、感光層に使用するバインダーと必要に応じて添加される添加剤により構成されている。保護層に添加される添加剤としては、熱現像後の画像の傷つき防止や搬送性を確保する目的でフィラーを含有することが好ましく、フィラーを添加する場合の含有量は、層形成組成物中０．０５〜３０質量％含有することが好ましい。
【０１０５】
さらに、滑り性や帯電性を改良するために保護層には潤滑剤、帯電防止剤を含有しても良い、このような潤滑剤としては、脂肪酸、脂肪酸エステル、脂肪酸アミド、ポリオキシエチレン、ポリオキシプロピレン、（変性）シリコーンオイル、（変性）シリコーン樹脂、フッ素樹脂、フッ化カーボン、ワックス等を挙げることができ、また、帯電防止剤としては、カチオン系界面活性剤、アニオン系界面活性剤、非イオン性界面活性剤、高分子帯電防止剤、金属酸化物または導電性ポリマー等、「１１２９０の化学商品」化学工業日報社、ｐ．８７５〜８７６等に記載の化合物、米国特許第５，２４４，７７３号カラム１４〜２０に記載された化合物等を挙げることができる。
【０１０６】
保護層は単層でも良く、組成が同一あるいは異なるの複数層の層で構成しても良い。なお、保護層の膜厚は１．０〜５．０μｍが好ましい。又、感光層、支持体および保護層以外に、支持体と感光層との膜付を改良するために中間層を設置しても良く、設置する場合の中間層の厚みは通常０．０５〜２．０μｍである。
【０１０７】
本発明に係るバック層は単層でも良く、組成が同一あるいは異なるの複数層の層で構成しても良い。なお、バック層の厚みは０．１〜１０μｍが好ましい。
【０１０８】
本発明の熱現像感光材料は、感光層に通過する光の量又は波長分布を制御するために感光層と同じ側にフィルター染料層および／又は反対側にアンチハレーション染料層、いわゆるバック層を形成し、感光層には染料又は顔料を含ませても良い。
【０１０９】
本発明の熱現像感光材料の保護層には前記のバインダーやマット剤と共に、さらにポリシロキサン化合物やワックスや流動パラフィンのようなスベリ剤を含有してもよい。
【０１１０】
本発明の熱現像感光材料には、塗布助剤として各種の界面活性剤が熱現像感光材料を構成している各層に用いられ、中でもフッ素系界面活性剤が、帯電特性を改良したり、斑点状の塗布故障を防ぐために好ましく用いられる。
【０１１１】
本発明に係る感光層は複数層にしても良く、また階調の調節のため感光層の構成として高感度層／低感度層又は低感度層／高感度層にしても良い。
【０１１２】
本発明の熱現像感光材料には、Ｒｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ第１７０２９号に開示されている色調剤が使用することが可能である。
【０１１３】
本発明の熱現像感光材料には、熱現像を抑制あるいは促進させ熱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る。
【０１１４】
本発明の熱現像感光材料には、かぶり防止剤が用いられてもよく、これらの添加剤は感光層、非感光層の何れに添加してもいい。
【０１１５】
本発明の熱現像感光材料には、例えば、界面活性剤、酸化防止剤、安定化剤、可塑剤、被覆助剤等を用いても良い。これらの添加剤及び上述したその他の添加剤はＲｅｓｅａｒｃｈ Ｄｉｓｃｌｏｓｕｒｅ Ｉｔｅｍ１７０２９（１９７８年６月ｐ．９〜１５）に記載されている化合物を好ましく用いることができる。
【０１１６】
二級または三級アミノ基を有するアルコキシシラン化合物及びポリエチレンイミンを、熱現像感光材料を構成している感光層又は感光層の上部に積層された保護層と、バック層又はバック保護層とにに含有させる方法としては特に制限は無く、そのまま必要量を塗工液に添加しても良いし、必要に応じて適当な溶媒で希釈して塗工液に添加してもよい。
【０１１７】
本発明に係る感光層用の塗工液、保護層用の塗工液、および必要に応じて設置される中間層およびバック層用の塗工液は、上述した各添加剤をそれぞれ溶媒に溶解、若しくは分散して調製することが可能である。
【０１１８】
溶媒としては、有機合成化学協会編の“溶剤ポケットブック”等に示されている溶解度パラメーターの値が６．０〜１５．０の範囲のものであればよく、本発明において用いられる各層を形成する塗工液に用いる溶媒としては、例えば、ケトン類としてアセトン、イソフォロン、エチルアミルケトン、メチルエチルケトン、メチルイソブチルケトン等が挙げられる。アルコール類としてメチルアルコール、エチルアルコール、ｎ−プロピルアルコール、イソプロピルアルコール、ｎ−ブチルアルコール、イソブチルアルコール、ジアセトンアルコール、シクロヘキサノール、ベンジルアルコール等が挙げられる。グリコール類としてエチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、ヘキシレングリコール等が挙げられる。エーテルアルコール類としてエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル等が挙げられる。エーテル類としてエチルエーテル、ジオキサン、イソプロピルエーテル等が挙げられる。
【０１１９】
エステル類としては、酢酸エチル、酢酸ブチル、酢酸アミル、酢酸イソプロピル等が挙げられる。炭化水素類としてｎ−ペンタン、ｎ−ヘキサン、ｎ−ヘプタン、シクロヘキサン、ベンゼン、トルエン、キシレン等が挙げられる。塩化物類として塩化メチル、塩化メチレン、クロロホルム、ジクロロベンゼン等が挙げられるが、但し、本発明の効果を阻害しない範囲であればこれらに限定されない。
【０１２０】
また、これらの溶媒は、単独、または、数種類組合わせて使用できる。尚、画像形成材料中の上記溶媒の含有量は塗布工程後の乾燥工程等における温度条件等の条件変化によって調整でき、熱現像感光材料中に含有される残存溶媒の量は合計量で５〜１０００ｍｇ／ｍ^２が好ましく、更に好ましくは、１０〜３００ｍｇ／ｍ^２である。
【０１２１】
塗工液を形成する際に分散が必要な場合には、二本ロールミル、三本ロールミル、ボールミル、ペブルミル、コボルミル、トロンミル、サンドミル、サンドグラインダー、Ｓｑｅｇｖａｒｉアトライター、高速インペラー分散機、高速ストーンミル、高速度衝撃ミル、ディスパー、高速ミキサー、ホモジナイザ、超音波分散機、オープンニーダー、連続ニーダー等、従来から公知の分散機を適時選択してを用いることができる。
【０１２２】
上述のようにして調製した、塗工液を塗工するには、エクストルージョン方式の押し出しコータ、リバースロールコータ、グラビアロールコータ、エアドクターコータ、ブレードコータ、エアナイフコータ、スクイズコータ、含浸コータ、バーコータ、トランスファロールコータ、キスコータ、キャストコータ、スプレーコータ等の、公知の各種コータステーションを適時選択して用いることができる。これらのコータの中で、該層の厚みムラを無くすために、エクストルージョン方式の押し出しコータやリバースロールコータ等のロールコータを用いることが好ましい。
【０１２３】
各層毎に塗布乾燥を繰り返してもよいが、ウェット−オン−ウェット方式で重層塗布して乾燥させても良い。その場合、リバースロールコータ、グラビアロールコータ、エアドクターコータ、ブレードコータ、エアナイフコータ、スクイズコータ、含浸コータ、バーコータ、トランスファロールコータ、キスコータ、キャストコータ、スプレーコータ等とエクストルージョン方式の押し出しコータとの組み合わせにより塗布することができ、この様なウェット−オン−ウェット方式における重層塗布においては、下側の層が湿潤状態になったままで上側の層を塗布するので、上下層間の接着性が向上する。
【０１２４】
本発明では少なくとも感光層形成塗工液を塗工後、本発明の目的を有効に引き出すために、塗膜を乾燥させる温度が６５〜１００℃の範囲であることが好ましい。乾燥温度が６５℃よりも低い場合は、反応が不十分であるため、経時による感度の変動が起こる場合が有り、また１００℃よりも高い場合には、製造直後の熱現像感光材料自身にかぶり（着色）を生じる場合がある為好ましくない。乾燥時間は乾燥時の風量により一概に規定できないが、通常２〜３０分の範囲で乾燥させることが好ましい。乾燥温度は、塗工後直ぐに前述の温度範囲の乾燥温度で乾燥させても良いし、乾燥の際に生じる塗工液のマランゴニーや、温風の乾燥風によって生じる表面近傍が初期に乾燥してしまうことによって生じるムラ（ユズ肌）を防止する目的で、初期の乾燥温度を６５℃よりも低温で行い、その後前述の温度範囲の乾燥温度で乾燥させても良い。
【０１２５】
本発明の熱現像感光材料は、防湿層、保湿層を設けることができる。防湿層とは、水蒸気透過率が０．００５ｇ／ｍ^２以上、０．１ｇ／ｍ^２以下のものを指す。防湿に関しては水蒸気透過率は低くても何ら問題はないが、上限は０．１ｇ／ｍ^２以下でないと防湿層の効果は得られにくい。保湿層とは、吸水率が０．５％以上、１００％以下のものを指す。吸水率が０．５％以上でないと保湿の効果が出ないため低湿下での画像性能の改善が期待できず、１００％以下でないと今度は水分量が多くなり過ぎてしまい、カブリを悪化させる原因となる。防湿層および保湿層に用いられる素材としては特に制限は無い。
【０１２６】
防湿層に用いる好ましい素材としては、ポリビニルアルコール、ポリ塩化ビニリデン、ポリオレフィン、ポリフッ化エチレン、ポリフッ化塩化エチレン、ポリフッ化ビニル、ポリエチレン、ポリプロピレン、ポリスチレン、ポリエチレンテレフタレート、ポリ塩化ビニル、塩素化ポリ塩化ビニル、ポリアクリロニトリル、塩酸ゴム、塩化ビニリデン−塩化ビニル共重合物、塩化ビニリデン−アクリロニトリル共重合物、塩化ビニリデン−イソブチレン共重合物、塩化ビニル−フマル酸ジエチル共重合物などがあげられる。
【０１２７】
上記バインダーを溶解または分散するための主溶媒としては、水のほかには有機溶媒が主として用いられ、例えばアルコール類（メタノール、エタノール、プロパノール）、ケトン類（アセトン、メチルエチルケトン）ジメチルホルムアミド、ジメチルスルホキシド、メチルセルソルブ等が好ましく用いられる。
【０１２８】
保湿層に用いる好ましい素材としては、メタクリル酸メチル、セルロース系樹脂、ポリエチレン系樹脂、ポリアミド、オレフィンビニルアルコール共重合体、エチレンビニルアセテートコポリマー樹脂などがあげられる。
【０１２９】
上記バインダーを溶解または分散するための主溶媒としては前述と同様に、水のほかには有機溶媒が主として用いられ、例えばアルコール類（メタノール、エタノール、プロパノール）、ケトン類（アセトン、メチルエチルケトン）ジメチルホルムアミド、ジメチルスルホキシド、メチルセルソルブ等が好ましく用いられる。
【０１３０】
【実施例】
以下、実施例を挙げて本発明を詳細に説明するが、本発明の態様はこれに限定されない。
【０１３１】
実施例１
〈下引済みＰＥＴ支持体１の作製〉
帝人（株）製の２軸延伸熱固定済みの厚さ１２５μｍ、幅１０００ｍｍ、長さ２０００ｍのＰＥＴフィルムの両面に下記に示す条件でプラズマ処理１を施し、次いで一方の面に下記の下引塗布液ａ−１を乾燥膜厚０．８μｍになるように塗設し乾燥させて下引層Ａ−１とし、また反対側の面に下記帯電防止用の下引塗布液ｂ−１を乾燥膜厚０．８μｍになるように塗設し乾燥させて帯電防止加工下引層Ｂ−１とした。ついで、それぞれの下引層表面に下記に示す条件でプラズマ処理２を施した。
【０１３２】
《プラズマ処理１、２条件》
バッチ式の大気圧プラズマ処理装置（イーシー化学（株）製、ＡＰ−Ｉ−Ｈ−３４０）を用いて、高周波出力が４．５ｋＷ、周波数が５ｋＨｚ、処理時間が５秒及びガス条件としてアルゴン、窒素及び水素の体積比をそれぞれ９０％、５％及び５％で行った。
【０１３３】

《支持体の熱処理》
上記の下引済み支持体の下引乾燥工程において、支持体を１４０℃で加熱し、その後徐々に冷却した。その際に１×１０^５Ｐａの張力で搬送した。
【０１３４】
《バック層面側塗布》
以下の組成のバック層塗布液とバック保護層塗布液を、それぞれ塗布前に準絶対濾過精度２０μｍのフィルタを用いて濾過した後、押し出しコーターで前記作製した支持体の帯電防止加工した下引層Ｂ−１面上に、合計ウェット膜厚が３０μｍになるよう、毎分１２０ｍの速度で同時重層塗布し、下引済みＰＥＴ支持体１を得た。
【０１３５】

なお、表１において、一般式（Ｆ）で表される界面活性剤の欄における比較化合物１とは、Ｃ_８Ｆ_１７ＳＯ_３Ｌｉである。
【０１３６】
〈感光層の作製〉
《感光性ハロゲン化銀乳剤Ｂの調製》
Ａ１
フェニルカルバモイルゼラチン ８８．３ｇ
化合物（Ａ）（１０％メタノール溶液） １０ｍｌ
臭化カリウム ０．３２ｇ
水で５４２９ｍｌに仕上げる
Ｂ１
０．６７Ｍ／Ｌ硝酸銀水溶液 ２６３５ｍｌ
Ｃ１
臭化カリウム ５１．５５ｇ
沃化カリウム １．４７ｇ
水で６６０ｍｌに仕上げる
Ｄ１
臭化カリウム １５４．９ｇ
沃化カリウム ４．４１ｇ
塩化イリジウム（１％溶液） ０．９３ｍｌ
Ｅ１
０．４Ｍ／Ｌ臭化カリウム水溶液 下記銀電位制御量
Ｆ１
５６％酢酸水溶液 １６．０ｍｌ
Ｇ１
無水炭酸ナトリウム １．７２ｇ
水で１５１ｍｌに仕上げる
化合物（Ａ）：
ＨＯ（ＣＨ_２ＣＨ_２Ｏ）ｎ−［ＣＨ（ＣＨ_３）ＣＨ_２Ｏ］_１７−（ＣＨ_２ＣＨ_２Ｏ）_ｍＨ ｍ＋ｎ＝５〜７
特公昭５８−５８２８８号、同５８−５８２８９号の各公報に示される混合撹拌機を用いて溶液Ａ１に溶液Ｂ１の１／４量及び溶液Ｃ１全量を４５℃、銀電位（ｐＡｇ）を８．０９に制御しながら、同時混合法により４分４５秒を要して添加し、核形成を行った。
【０１３７】
７分間経過後、溶液Ｂ１の残り及び溶液Ｄ１の全量を、温度４５℃、ｐＡｇ８．０９に制御しながら、同時混合法により１４分１５秒かけて添加した。混合中、反応溶液のｐＨは５．６であった。
【０１３８】
５分間撹拌した後、４０℃に降温し、溶液Ｆ１を全量添加し、ハロゲン化銀乳剤を沈降させた。沈降部分２０００ｍｌを残し上澄み液を取り除き、水を１０Ｌ加え、撹拌後、再度ハロゲン化銀乳剤を沈降させた。沈降部分１５００ｍｌを残し、上澄み液を取り除き、更に水を１０Ｌ加え、撹拌後、ハロゲン化銀乳剤を沈降させた。沈降部分１５００ｍｌを残し、上澄み液を取り除いた後、溶液Ｇ１を加え、６０℃に昇温し、更に１２０分撹拌した。最後にｐＨが５．８になるように調整し、銀量１モル当たり１１６１ｇになるように水を添加して感光性ハロゲン化銀乳剤Ｂを得た。得られた感光性ハロゲン化銀乳剤Ｂのハロゲン化銀粒子は平均粒子サイズが０．０５８μｍ、粒子サイズの変動係数が１２％、［１００］面比率が９２％の立方体沃臭化銀粒子であった。
【０１３９】
《粉末有機銀塩Ｂの調製》
４７２０ｍｌの純水にベヘン酸１３０．８ｇ、アラキジン酸６７．７ｇ、ステアリン酸４３．６ｇ、パルミチン酸２．３ｇを８０℃で溶解した。次に１．５Ｍ／Ｌの水酸化ナトリウム水溶液５４０．２ｍｌを添加し濃硝酸６．９ｍｌを加えた後、５５℃に冷却して脂肪酸ナトリウム溶液を得た。上記の脂肪酸ナトリウム溶液の温度を５５℃に保ったまま、３１．７ｇの上記の感光性ハロゲン化銀乳剤Ｂと純水４６５ｍｌを添加し５分間攪拌した。
【０１４０】
次に１Ｍ／Ｌの硝酸銀溶液７０２．６ｍｌを２分間かけて添加し、１０分間攪拌し有機銀塩分散物を得た。その後、得られた有機銀塩分散物を水洗容器に移し、脱イオン水を加えて攪拌後、静置させて有機銀塩分散物を浮上分離させ、下方の水溶性塩類を除去した。その後、排水の電導度が２μＳ／ｃｍになるまで脱イオン水による水洗、排水を繰り返し、遠心脱水を実施した後、気流式乾燥機フラッシュジェットドライヤー（株式会社セイシン企業製）を用いて、乾燥機入口熱風温度７５℃の運転条件により含水率が０．１％になるまで乾燥して粉末有機銀塩Ｂを得た。この時、乾燥熱風は大気中の空気を電気ヒーターで加熱したものを使用した。なお、粉末有機銀塩Ｂの含水率測定には赤外線水分計を使用した。
【０１４１】
《予備分散液Ｂの調製》
ポリビニルブチラール粉末「Ｂｕｔｖａｒ Ｂ−７９」（Ｍｏｎｓａｎｔｏ社製）１４．５７ｇをメチルエチルケトン（以下、ＭＥＫと略す）１４５７ｇに溶解し、ＶＭＡ−ＧＥＴＺＭＡＮＮ社製「ディゾルバＤＩＳＰＥＲＭＡＴ ＣＡ−４０Ｍ型攪拌機」により攪拌しながら粉末有機銀塩Ｂの５００ｇを徐々に添加して十分に混合することにより予備分散液Ｂを調製した。
【０１４２】
《感光性乳剤分散液Ｂの調製》
予備分散液Ｂをポンプを用いてミル内滞留時間が１０分間となるように、０．５ｍｍ径のジルコニアビーズ（東レ製トレセラム）を内容積の８０％充填したメディア型分散機ＤＩＳＰＥＲＭＡＴ ＳＬ−Ｃ１２ＥＸ型（ＶＭＡ−ＧＥＴＺＭＡＮＮ社製）に供給し、ミル周速１３ｍ／ｓにて分散を行なうことにより感光性乳剤分散液Ｂを調製した。
【０１４３】
《溶液ｄの調製》
化合物Ｐの０．１ｇ、化合物Ｑの０．１ｇをメタノール１０．１ｇに溶解し溶液ｄを作製した。
【０１４４】
《増感色素液ａの調製》
２９ｍｇの増感色素１、４．５ｇの２−クロロ−安息香酸、８．４ｇの溶液ｄおよび２８０ｍｇの５−メチル−２−メルカプトベンズイミダゾールを７７．２ｍｌのＭＥＫに暗所にて溶解し増感色素液ａを調製した。
【０１４５】
《添加液ａの調製》
１０７ｇの還元剤（例示化合物Ａ−４）および４．８ｇの４−メチルフタル酸をＭＥＫ２６１ｇに溶解し添加液ａとした。
【０１４６】
《添加液ｂの調製》
１１．６ｇのかぶり防止剤２をＭＥＫ１３７ｇに溶解し添加液ｂとした。
【０１４７】
《添加液ｃの調製》
２１．７ｇのアルコキシシラン化合物：Ｃ_６Ｈ_５−ＮＨ−（ＣＨ_２）−Ｓｉ−（ＯＣＨ_３）_３と４５ｇのかぶり防止剤３を１５９ｇのＭＥＫに溶解し添加液ｃとした。
【０１４８】
《添加液ｄの調製》
１ｍ^２あたり０．１７ｇになる量のフタラジンを１ｍ^２あたり２．７３ｇになる量のＭＥＫに溶解し添加液ｄとした。
【０１４９】
《感光層塗布液Ｅ−１の調製》
前記感光性乳剤分散液Ｂ（１６４１ｇ）およびＭＥＫの５０６ｇを撹拌しながら２１℃に保温し、かぶり防止剤１（１１．２％メタノール溶液）１０．７５ｇを加え、１時間撹拌した。さらに臭化カルシウム（１１．２％メタノール溶液）１３．６ｇを添加して２０分撹拌した。続いて、溶液ｄの１．３ｇを添加して１０分間撹拌した後、増感色素液ａを添加して１時間撹拌した。その後、温度を１３℃まで降温してさらに３０分撹拌した。１３℃に保温したまま、ポリビニルブチラール「Ｂｕｔｖａｒ Ｂ−７９」（Ｍｏｎｓａｎｔｏ社製）３４９．６ｇを添加して３０分撹拌した後、５−メチル−２−メルカプトベンズイミダゾール９５ｍｇと、テトラクロロフタル酸３．５ｇを添加して３０分間撹拌した。その後１．２ｇの５−ニトロインダゾール、０．４ｇの５−ニトロベンズイミダゾール、３．０ｇの硬調化剤Ｃ−６２（ビニル化合物）及びＭＥＫ２２５ｇを添加した。更に撹拌を続けながら、添加液ａ、添加液ｂ、添加液ｄをそれぞれ１４８．６ｇづつ、添加液ｃを２２５ｇ順次添加し撹拌することにより、感光層塗布液Ｅ−１を得た。
【０１５０】
《保護層塗布液の調製》
１ｍ^２あたりＭＥＫ３０ｇを攪拌しながら、セルロースアセテートブチレート（Ｅａｓｔｍａｎ Ｃｈｅｍｉｃａｌ社製、ＣＡＢ１７１−１５）：３．５ｇ、ポリメチルメタクリル酸（ローム＆ハース社製、パラロイドＡ−２１）：１６０ｍｇ、ベンゾトリアゾール：３５ｍｇ、フッ素系界面活性剤Ｆ−１：Ｃ_８Ｆ_１７ＳＯ_３Ｌｉの２０ｍｇ、フッ素系界面活性剤Ｆ−２：Ｃ_８Ｆ_１７（ＣＨ_２ＣＨ_２Ｏ）_２２Ｃ_８Ｆ_１７の６０ｍｇを添加し溶解した。次に下記に示すマット剤分散液３．５ｇを添加して攪拌し、保護層塗布液を調製した。
【０１５１】
《マット剤分散液の調製》
１ｍ^２当たり１．７ｇのＭＥＫに平均粒径３μｍの単分散シリカ５０ｍｇを添加し、ディゾルバ型ホモジナイザにて８０００ｒｐｍで３０分間分散し、マット剤分散液を調製した。
【０１５２】
【化１６】

【０１５３】
《感光層側の塗布》
上述した下引済みＰＥＴ支持体１の上に感光層、保護層の順で塗布を行った。前記感光層塗布液Ｅ−１と保護層塗布液を絶対濾過精度２０μｍのフィルタに通して濾過した後、エクストルージョン型ダイコーターを使用し、下引済みＰＥＴ支持体１の下引層Ａ−１の上に順次各層を毎分６０ｍの速度で塗布した。
【０１５４】
感光層の塗布を行い、その８秒後に、乾燥温度７５℃、露点温度１０℃の熱風を用いて５分間乾燥後にロール状に巻き取ることにより熱現像感光材料を作製した。
【０１５５】
得られた熱現像感光材料の感光層の塗布銀量１．５ｇ／ｍ^２、表面保護層は乾燥膜厚で２．５μｍであった。
【０１５６】
《評価》
作製した各試料を２３℃、２０％ＲＨ、および２３℃、８０％ＲＨの環境で８時間放置した後に、ウエッジ露光を行い、熱現像処理後、画像評価として最大濃度（Ｄｍａｘ）、最小濃度（Ｄｍｉｎ）を測定した結果を表１に示す。
【０１５７】
尚、最大濃度（Ｄｍａｘ）、最小濃度（Ｄｍｉｎ）の評価するための露光、現像処理は各試料を２５ｃｍ×３０ｃｍに切断して７８０ｎｍの半導体レーザーを有する感光計でウェッジを介して露光した。現像はＩｍａｔｉｏｎ社製フィルムプロセッサーｍｏｄｅｌ ２７７１を用い、１２０℃、４８秒の設定で熱現像処理した。その際、露光は２３℃、５０％ＲＨに調湿した部屋で行い、現像処理はそれぞれ２３℃、２０％ＲＨ、および２３℃、８０％ＲＨの環境で行った。
【０１５８】
〈Ｄｍａｘ及びＤｍｉｎの評価〉
Ｄｍａｘ及びＤｍｉｎについては、光学濃度計（Ｘ−ｒｉｔｅ社製）を用いて熱現像処理後の各試料のＤｍａｘ部及びＤｍｉｎ部のビジュアルの濃度を測定し、以下の評価ランクにより判定した。
【０１５９】
Ｄｍａｘについては、４．０以上は合格、４．０未満は不合格と判断した。また、Ｄｍｉｎについては、０．１１未満は合格、０．１１以上は不合格と判断した。
【０１６０】
【表１】

【０１６１】
表１から本発明の試料はいずれも優れた性能を示していることがわかる。
【０１６２】
【発明の効果】
本発明により、使用前の熱現像感光材料の保存時のカブリ増加、階調変動を押さえた熱現像感光材料を提供することができた。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention has a photosensitive layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, a contrast agent and a binder on a support, and at least one layer on the side of the support opposite to the photosensitive layer. The present invention relates to a photothermographic material having a back layer.
[0002]
[Prior art]
In the field of printing plate making and medical care, wastewater from wet processing of photosensitive materials has been a problem in terms of workability.In recent years, it has been strongly desired to reduce the amount of wastewater from the viewpoint of environmental protection and space saving. It is rare. Therefore, there has been a need for a technique relating to a photothermographic material capable of performing efficient exposure with a laser image setter or a laser imager and forming a high-resolution and clear black image. As a technique for this, silver halide photosensitive materials which form a photographic image by heat treatment are known, and these are described, for example, in U.S. Pat. Nos. 3,152,904 and 3,457,075 and D.C. Morgan and B.M. "Thermal Processed Silver Systems" by Shelly, Imaging Processes and Materials, Nebulette 8th Edition, Sturge, Sturge. Walworth, A .; Shepp Edit, page 2, 1969, and the like. Such a photothermographic material contains a reducible silver source (for example, an organic silver salt), a catalytically active amount of a photocatalyst (for example, silver halide), and a reducing agent usually in a state of being dispersed in an organic binder matrix. ing. The photothermographic material is stable at room temperature, but when heated to a high temperature after exposure, generates silver by a redox reaction between a reducible silver source (acting as an oxidizing agent) and a reducing agent. This oxidation-reduction reaction is promoted by the catalytic action of the latent image generated by the exposure. The silver formed by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas and results in image formation.
[0003]
Since the photothermographic material uses an organic silver salt as a silver source, when water is present in the layer of the photothermographic material, the water dissociates silver ions from the organic silver salt and contains a reducing agent. This is known as one of the causes of increasing the fog or changing the gradation during storage of the photothermographic material after production.
[0004]
As a countermeasure against such a problem, for example, a technique of reducing the fluctuation of the developing temperature and the fluctuation of the concentration over time by keeping the amount of the residual solvent after coating constant (see Patent Document 1), an equilibrium water content at 25 ° C. and 60% RH Using a support having a water content of 2% by mass or less, and applying a coating solution having a water content of 2% by mass or less and drying the photothermographic material so that the residual solvent ratio of the photothermographic material is 2.0% by mass or less. Developed photosensitive materials (see Patent Document 2) and the like are known.
[0005]
However, these techniques are not enough to prevent an increase in fog and a change in image quality during storage of the photothermographic material before use.
[0006]
[Patent Document 1]
JP-A-6-301140
[0007]
[Patent Document 2]
JP 2000-310830 A
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photothermographic material which suppresses an increase in fog and gradation fluctuation during storage of the photothermographic material before use. .
[0009]
[Means for Solving the Problems]
The above object of the present invention can be achieved by the following means.
[0010]
(1) On a support, there is provided a photosensitive layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, a contrasting agent and a binder, and at least one layer on the opposite side of the support from the photosensitive layer. Wherein the back layer contains a compound that reacts with formic acid and a surfactant represented by the following general formula (F).
[0011]
General formula (F) X- (L)_m-Rf- (L ')_m-X '
[Wherein, Rf represents an aliphatic group having at least one fluorine atom, L and L ′ represent a simple bond or a divalent linking group, m represents 0 or an integer of 1 to 5, X and X ′ represents a hydrogen atom, a hydroxyl group, an anionic group or a cationic group. ]
(2) The photothermographic material according to (1), wherein the compound that reacts with formic acid is a compound represented by the following general formula (1).
[0012]
General formula (1) R-NH₂
[In the formula, R represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, an alkylamino group or an arylamino group, each of which may have a substituent. ]
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments and a method of the photothermographic material of the invention will be described in detail.
[0014]
The feature of the photothermographic material of the present invention is that, first, a photothermographic material having a photosensitive layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, a high contrast agent and a binder on a support, A photothermographic material having at least one back layer on the side of the support opposite to the photosensitive layer; secondly, a compound which reacts with formic acid in the back layer and the surface activity represented by the formula (F) Agent.
[0015]
It is important that the back layer simultaneously contains a compound that reacts with formic acid and a surfactant represented by the above general formula (F), whereby the fog increases during storage of the photothermographic material prior to use, and the level is reduced. Key fluctuations can be suppressed. The back layer according to the present invention may be one layer or two layers. When the back layer has two layers, the compound reacting with formic acid and the surfactant represented by the formula (F) may be the same layer or separate layers.
[0016]
(Compound that reacts with formic acid)
The compound that reacts with formic acid will be described.
[0017]
The type of the compound that reacts with formic acid is not particularly limited as long as the compound exhibits the desired effect when used in combination with the surfactant represented by Formula (F). Specifically, alcohols (eg, dodecyl alcohol, p-tert-butylphenol), alkyl halides (eg, 1,6-dibromohexane, 1-iododecane), acid anhydrides (eg, acetic anhydride, phthalic anhydride) ), Acid halides (eg, p-toluenesulfonyl chloride, benzoyl chloride), carbodiimides (eg, dicyclohexylcarbodiimide, diisopropylcarbodiimide), amines (eg, dodecylamine, p-butylaniline), hydrazines (eg, N, N- Examples thereof include dibenzylhydrazine, p-hydrazinobenzoic acid) and diazoalkanes (for example, diazomethane). Among them, a compound represented by the general formula (1) is preferable.
[0018]
General formula (1) R-NH₂
In the general formula (1), R represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, an alkylamino group or an arylamino group, each of which may have a substituent.
[0019]
The alkyl group represented by R means a linear, branched, cyclic, substituted or unsubstituted alkyl group, and an alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, for example, methyl, ethyl, n-propyl, Isopropyl, tert-butyl, n-octyl, n-decyl, n-dodecyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, 2-ethylhexyl), cycloalkyl group (preferably substituted or unsubstituted having 3 to 30 carbon atoms) A cycloalkyl group, for example, cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl), a bicycloalkyl group (preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a bicyclo having 5 to 30 carbon atoms) This is a monovalent group obtained by removing one hydrogen atom from an alkane, for example, bicyclo [1,2, ] Heptan-2-yl, bicyclo [2,2,2] octan-3-yl) encompasses such further a tricyclo structure having many cyclic structures.
[0020]
The alkenyl group represented by R means a linear, branched, or cyclic, substituted or unsubstituted alkenyl group, and is an alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, for example, vinyl, Allyl, prenyl, geranyl, oleyl), a cycloalkenyl group (preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms, that is, a monovalent obtained by removing one hydrogen atom from a cycloalkene having 3 to 30 carbon atoms) For example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl), a bicycloalkenyl group (substituted or unsubstituted bicycloalkenyl group, preferably substituted or unsubstituted having 5 to 30 carbon atoms) Bicycloalkenyl group, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkene having one double bond. . For example, bicyclo [2,2,1] hept-2-en-1-yl, bicyclo [2,2,2] oct-2-en-4-yl) also like encompass. The alkynyl group represented by R preferably represents a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, for example, ethynyl, propargyl, phenylethynyl, trimethylsilylethynyl and the like.
[0021]
The aryl group represented by R preferably represents a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (eg, phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl). The heterocyclic group represented by R is preferably a monovalent group obtained by removing one hydrogen atom from a 5- or 6-membered, substituted or unsubstituted, aromatic or non-aromatic heterocyclic compound, More preferably, a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms (for example, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl, 4-triazolyl, 2-pyridyl, 2-pyridyl, Quinolyl). The alkylamino group represented by R is preferably a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms (for example, methylamino, dimethylamino, ethylamino, tert-butylamino, dibenzylamino, dodecylamino and the like) ), And the arylamino group represented by R represents a substituted or unsubstituted arylamino group having 6 to 30 carbon atoms (eg, anilino, N-methyl-anilino, diphenylamino).
[0022]
When R has a substituent, examples of the substituent include a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a hydroxyl group, a nitro group, a carboxyl group, an alkoxy group, and an aryl group. Oxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including anilino group), acylamino group, aminocarbonylamino group, alkoxycarbonylamino group , Aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl , Alkyl and arylsulfonyl groups, acyl groups, aryloxycarbonyl groups, alkoxycarbonyl groups, carbamoyl groups, aryl and heterocyclic azo groups, imide groups, phosphino groups, phosphinyl groups, phosphinyloxy groups, phosphinylamino groups, A silyl group.
[0023]
More specifically, a halogen atom (eg, a chlorine atom, a bromine atom, an iodine atom) and an alkyl group [representing a linear, branched, or cyclic substituted or unsubstituted alkyl group. Alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, for example, methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-octyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, 2-ethylhexyl), cycloalkyl Group (preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, for example, cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl), a bicycloalkyl group (preferably substituted or unsubstituted having 5 to 30 carbon atoms). It is a substituted bicycloalkyl group, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, for example, bicyclo [1,2,2] heptane-2-yl, bicyclo [2, 2,2] octan-3-yl), and a tricyclo structure having more ring structures. . An alkyl group (for example, an alkyl group of an alkylthio group) among the substituents described below also represents an alkyl group having such a concept. ], An alkenyl group [which represents a linear, branched, or cyclic substituted or unsubstituted alkenyl group. Alkenyl groups (preferably substituted or unsubstituted alkenyl groups having 2 to 30 carbon atoms, for example, vinyl, allyl, prenyl, geranyl, oleyl), cycloalkenyl groups (preferably substituted or unsubstituted 3 to 30 carbon atoms); A cycloalkenyl group, that is, a monovalent group obtained by removing one hydrogen atom from a cycloalkene having 3 to 30 carbon atoms, for example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl), a bicycloalkenyl group (A substituted or unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom of a bicycloalkene having one double bond. For example, bicyclo [2,2,1] hept-2-en-1-yl, bicyclo [2,2,2] oct -2-en-4-yl)]], an alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, for example, ethynyl, propargyl, trimethylsilylethynyl group, an aryl group (preferably having 6 to 30 carbon atoms) 30 substituted or unsubstituted aryl groups such as phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl), heterocyclic groups (preferably 5- or 6-membered substituted or unsubstituted aromatic groups) A monovalent group obtained by removing one hydrogen atom from an aromatic or non-aromatic heterocyclic compound, and more preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms. , 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl), cyano group, hydroxyl group, nitro group, carboxy And an alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, for example, methoxy, ethoxy, isopropoxy, tert-butoxy, n-octyloxy, 2-methoxyethoxy), an aryloxy group (Preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, for example, phenoxy, 2-methylphenoxy, 4-tert-butylphenoxy, 3-nitrophenoxy, 2-tetradecanoylaminophenoxy), silyloxy Group (preferably a silyloxy group having 3 to 20 carbon atoms, for example, trimethylsilyloxy, tert-butyldimethylsilyloxy), a heterocyclic oxy group (preferably a substituted or unsubstituted heterocyclic oxy group having 2 to 30 carbon atoms) , 1-phenyltetrazol-5-oxy, 2 -Tetrahydropyranyloxy), acyloxy group (preferably formyloxy group, substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms, for example, Formyloxy, acetyloxy, pivaloyloxy, stearoyloxy, benzoyloxy, p-methoxyphenylcarbonyloxy), carbamoyloxy group (preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms, for example, N, N- Dimethylcarbamoyloxy, N, N-diethylcarbamoyloxy, morpholinocarbonyloxy, N, N-di-n-octylaminocarbonyloxy, Nn-octylcarbamoyloxy), alkoxycarbonyloxy group (preferably A substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, for example, methoxycarbonyloxy, ethoxycarbonyloxy, tert-butoxycarbonyloxy, n-octylcarbonyloxy), an aryloxycarbonyloxy group (preferably having 7 to 30 carbon atoms) 30 substituted or unsubstituted aryloxycarbonyloxy groups, for example, phenoxycarbonyloxy, p-methoxyphenoxycarbonyloxy, pn-hexadecyloxyphenoxycarbonyloxy), an amino group (preferably an amino group, having 1 carbon atom) To 30 substituted or unsubstituted alkylamino groups and substituted or unsubstituted anilino groups having 6 to 30 carbon atoms, such as amino, methylamino, dimethylamino, anilino, N-methyl-anilino, diphenylamido ), An acylamino group (preferably a formylamino group, a substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted arylcarbonylamino group having 6 to 30 carbon atoms, for example, formylamino, acetyl Amino, pivaloylamino, lauroylamino, benzoylamino, 3,4,5-tri-n-octyloxyphenylcarbonylamino), aminocarbonylamino group (preferably substituted or unsubstituted aminocarbonylamino having 1 to 30 carbon atoms, For example, carbamoylamino, N, N-dimethylaminocarbonylamino, N, N-diethylaminocarbonylamino, morpholinocarbonylamino), alkoxycarbonylamino group (preferably substituted or unsubstituted alkoxycarbonyl having 2 to 30 carbon atoms) Amino group, for example, methoxycarbonylamino, ethoxycarbonylamino, tert-butoxycarbonylamino, n-octadecyloxycarbonylamino, N-methyl-methoxycarbonylamino), aryloxycarbonylamino group (preferably having 7 to 30 carbon atoms) A substituted or unsubstituted aryloxycarbonylamino group, for example, phenoxycarbonylamino, p-chlorophenoxycarbonylamino, mn-octyloxyphenoxycarbonylamino), a sulfamoylamino group (preferably having 0 to 30 carbon atoms) Substituted or unsubstituted sulfamoylamino groups such as sulfamoylamino, N, N-dimethylaminosulfonylamino, Nn-octylaminosulfonylamino), alkyl and arylsulfonyl A mino group (preferably substituted or unsubstituted alkylsulfonylamino having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfonylamino having 6 to 30 carbon atoms, for example, methylsulfonylamino, butylsulfonylamino, phenylsulfonylamino, , 3,5-trichlorophenylsulfonylamino, p-methylphenylsulfonylamino), mercapto group, alkylthio group (preferably substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms, for example, methylthio, ethylthio, n-hexadecylthio) An arylthio group (preferably substituted or unsubstituted arylthio having 6 to 30 carbon atoms, for example, phenylthio, p-chlorophenylthio, m-methoxyphenylthio), a heterocyclic thio group (preferably substituted with 2 to 30 carbon atoms or Nothing A heterocyclic thio group, for example, 2-benzothiazolylthio, 1-phenyltetrazol-5-ylthio), a sulfamoyl group (preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms, for example, N-ethylsulfur) Famoyl, N- (3-dodecyloxypropyl) sulfamoyl, N, N-dimethylsulfamoyl, N-acetylsulfamoyl, N-benzoylsulfamoyl, N- (N'-phenylcarbamoyl) sulfamoyl), sulfo Groups, alkyl and arylsulfinyl groups (preferably a substituted or unsubstituted alkylsulfinyl group having 1 to 30 carbon atoms, a substituted or unsubstituted arylsulfinyl group having 6 to 30 carbon atoms, for example, methylsulfinyl, ethylsulfinyl, phenylsulfinyl, p-methylphenyl sulphie Yl), alkyl and arylsulfonyl groups (preferably substituted or unsubstituted alkylsulfonyl groups having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfonyl groups having 6 to 30 carbon atoms, for example, methylsulfonyl, ethylsulfonyl, phenylsulfonyl) , P-methylphenylsulfonyl), an acyl group (preferably a formyl group, a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyl group having 7 to 30 carbon atoms, for example, acetyl, Pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, pn-octyloxyphenylcarbonyl), an aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, for example, phenoxycarbonyl, o-chloro Phenoxycarbonyl, m-nitrophenoxycarbonyl, p-tert-butylphenoxycarbonyl), an alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, for example, methoxycarbonyl, ethoxycarbonyl, tert -Butoxycarbonyl, n-octadecyloxycarbonyl), carbamoyl group (preferably substituted or unsubstituted carbamoyl having 1 to 30 carbon atoms, for example, carbamoyl, N-methylcarbamoyl, N, N-dimethylcarbamoyl, N, N- Di-n-octylcarbamoyl, N- (methylsulfonyl) carbamoyl), aryl and heterocyclic azo groups (preferably substituted or unsubstituted arylazo groups having 6 to 30 carbon atoms, substituted or unsubstituted having 3 to 30 carbon atoms) F Rocyclic azo groups such as phenylazo, p-chlorophenylazo, 5-ethylthio-1,3,4-thiadiazol-2-ylazo), imide groups (preferably N-succinimide and N-phthalimido), and phosphino groups (preferably Is a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms, for example, dimethylphosphino, diphenylphosphino, methylphenoxyphosphino), a phosphinyl group (preferably substituted or unsubstituted phosphinyl having 2 to 30 carbon atoms) Groups such as phosphinyl, dioctyloxyphosphinyl, diethoxyphosphinyl), and phosphinyloxy groups (preferably substituted or unsubstituted phosphinyloxy groups having 2 to 30 carbon atoms, for example, diphenoxyphosphonyl) Finyloxy, dioctyloxyphosphinyloxy), e A sphinylamino group (preferably a substituted or unsubstituted phosphinylamino group having 2 to 30 carbon atoms, for example, dimethoxyphosphinylamino, dimethylaminophosphinylamino), a silyl group (preferably having 3 carbon atoms); To 30 substituted or unsubstituted silyl groups, for example, trimethylsilyl, tert-butyldimethylsilyl, phenyldimethylsilyl). Among the above functional groups, those having a hydrogen atom may be removed, and further substituted with the above group.
[0024]
Of the compounds represented by the general formula (1), R is more preferably an alkyl group, an alkylamino group, or an arylamino group, and even more preferably R is an alkylamino group or an arylamino group.
[0025]
It is also preferable that the compound represented by the general formula (1) has a diffusion-resistant group in a photographic coupler or the like, that is, a so-called ballast group. The ballast group specifically represents an aliphatic group, an aromatic group, or a heterocyclic group having 8 or more carbon atoms, preferably 8 to 24 carbon atoms. The aliphatic group is a substituted or unsubstituted, linear, branched, or cyclic alkyl group, alkenyl group, or alkynyl group, and is preferably an alkyl group. The aromatic group is a monocyclic or bicyclic aryl group, and specific examples include a substituted phenyl group and a substituted naphthyl group. The heterocyclic group is a 3- to 10-membered, saturated or unsaturated, substituted or unsubstituted heterocyclic ring containing at least one of N, O, and S atoms, which may be a monocyclic ring. Alternatively, a condensed ring may be formed with another aromatic ring or hetero ring. The heterocyclic ring is preferably a 5- or 6-membered aromatic heterocyclic ring, for example, those containing a pyridyl group, imidazolyl group, quinolinyl group, benzimidazolyl group, pyrimidyl group, pyrazolyl group, isoquinolinyl group, thiazolyl group, benzthiazolyl group are preferable. .
[0026]
More preferably, the ballast group of the compound represented by the general formula (1) is a substituted or unsubstituted alkyl group, aryl group, alkoxy group, acylamino group, ureido group, sulfonamide group, carbamoyl group, oxycarbonyl group. As these substituents, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an oxycarbonyl group, a carbamoyl group, an acylamino group, a sulfonamide group, a carbonyloxy group, a ureido group, a sulfamoyl group, a carboxy group, Examples thereof include a sulfo group and a group composed of a combination thereof. When the compound represented by the formula (1) has a ballast group, more preferably, R is an alkyl group, an alkylamino group, or an arylamino group, and even more preferably, R is an alkylamino group or an arylamino group. It is.
[0027]
It is also preferable that the compound represented by the general formula (1) has an acidic functional group or a salt thereof. The acidic functional group of the compound represented by the general formula (1) is preferably a functional group forming a Bronsted acid, and more preferably a functional group having a pKa value of 7 or less in water. Preferred examples of the acidic functional group in the present invention include an acidic functional group containing a carboxyl group, a sulfo group, and phosphorus, and a carboxyl group and a sulfo group are particularly preferred. When the compound represented by the general formula (1) has a salt of an acidic functional group, an alkali metal salt (eg, Na salt, K salt, etc.) or an alkaline earth metal salt (eg, Ca salt) of the acidic functional group is used. Salts, Mg salts, Ba salts, etc.), ammonium salts, phosphonium salts, and sulfonium salts. When the salt of the acidic functional group is an ammonium salt, a phosphonium salt, or a sulfonium salt, it is also preferable that the salt is an intramolecular salt. When the compound represented by the formula (1) has an acidic functional group or a salt thereof, R is preferably an alkyl group, an alkylamino group, or an arylamino group, and more preferably, R is an alkylamino group or an arylamino group. This is the case for an amino group.
[0028]
In the present invention, as the compound that reacts with formic acid, a polymer containing the structure represented by the general formula (1) as a partial structure can also be preferably used. Here, “including the structure represented by the general formula (1) as a partial structure” typically means a monovalent group obtained by removing one hydrogen atom of R constituting the compound of the general formula (1). Is included. The polymer used in the present invention is a homopolymer derived from a monomer represented by the following general formula (2) or a monomer represented by the following general formula (2) and a monomer represented by the following general formula (1) A copolymer with at least one monomer having at least one ethylene group which does not have a partial structure represented by
[0029]
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[0030]
Where R¹Represents a hydrogen atom, a chlorine atom, an alkyl group or an aryl group;¹Is -C (= O) N (R²)-, -C (= O) O-, -N (R²) Represents C (= O)-and -OC (= O)-. R²Represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. L²Is L¹And R 'represent a divalent linking group, and i and j each represent 0 or 1. H₂N-R'- represents a monovalent group obtained by removing one hydrogen atom of R constituting the compound of the general formula (1). In the general formula (2), R¹Is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms. Most preferably, it is a hydrogen atom or a methyl group. R²Is preferably a hydrogen atom, an unsubstituted alkyl group or an unsubstituted aryl group, and more preferably a hydrogen atom or an unsubstituted alkyl group. Most preferably, it is a hydrogen atom. In the general formula (2), L²And the divalent linking group represented by -O-, -S-, -N (R_N)-, (R_NRepresents a hydrogen atom, an alkyl group, or an aryl group), -C (= O)-, -C (= S)-, -SO₂—, —SO—, —P (＝ O) —, an alkylene group, an arylene group, and the like, alone or in combination. Specific examples of the group consisting of the combination include -arylene group-alkylene group-, -alkylene group-O-alkylene group-, -arylene group-O-alkylene group-, -alkylene group-O-alkylene group-O -Alkylene group -O-arylene group -O-, -arylene group -O-, -alkylene group -N (R_N)-, -Arylene group-N (R_N)-, -Alkylene group -C (= O) O-, -arylene group -C (= O) O-, -alkylene group -C (= O) N (R_N)-, -Arylene group -C (= O) N (R_N)-And the like. In addition, these groups may be connected from either side. In the general formula (2), preferred H₂N-R'- can be a monovalent group obtained by removing one hydrogen atom of R, which is a preferable example of the compound of the above general formula (1).
[0031]
Next, specific examples of the composition of the compound represented by the general formula (1), the monomer represented by the general formula (2), and the synthesized polymer are shown below. However, compounds that can be used in the present invention as compounds that react with formic acid are not limited to these.
[0032]
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[0033]
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[0034]
Embedded image

[0035]
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[0036]
Embedded image

[0037]
The compound that reacts with formic acid according to the present invention represented by the compound represented by the general formula (1) and the like includes water or a suitable organic solvent such as alcohols (methanol, ethanol, propanol, fluorinated alcohol), ketones (Acetone, methyl ethyl ketone), dimethylformamide, dimethylsulfoxide, methylcellosolve and the like. Also, by the well-known emulsification dispersion method, dibutyl phthalate, tricresyl phosphate, oil such as glyceryl triacetate or diethyl phthalate, dissolved using an auxiliary solvent such as ethyl acetate or cyclohexanone, mechanically emulsified dispersion. Can be prepared and used. Alternatively, the compound powder can be dispersed and used in a suitable solvent such as water by a ball mill, a colloid mill, a sand grinder mill, a Manton-Gaulin, a microfluidizer or an ultrasonic wave by a method known as a solid dispersion method.
[0038]
The amount of the compound represented by the general formula (1) is 1 × 10^-6１1 mol is preferred, and 1 × 10^-6~ 5 × 10^-1More preferably 2 × 10^-6~ 4 × 10^-1Molar is most preferred. When a polymer containing the structure represented by the general formula (1) as a partial structure is used, the amount of addition is 0.1 mg / m 2.²~ 2g / m²Is preferred, and 0.2 mg / m²~ 1g / m²Is more preferable, and 0.2 mg / m²~ 0.5g / m²Is most preferred. These may be used alone or in combination of two or more.
[0039]
[Surfactant represented by Formula (F)]
Next, the surfactant represented by formula (F) used in combination with the compound that reacts with formic acid according to the present invention will be described.
[0040]
General formula (F) X- (L) m-Rf- (L ') m-X'
In the formula, Rf represents an aliphatic group having at least one fluorine atom. The aliphatic group preferably has 1 to 18 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 3 to 7 carbon atoms. L and L 'represent a simple bond or a divalent linking group. As the divalent linking group, a sulfonamide group, an alkylene oxide group, a phenoxy group, and an alkylenecarbonyl group are particularly preferable. m represents 0 or an integer of 1 to 5. X and X 'represent a hydrogen atom, a hydroxyl group, an anionic group or a cationic group. The anionic group is preferably a carboxyl group, a sulfonic group, or a phosphate group, and the counter cation of the anionic group is preferably an alkali metal ion such as a sodium ion, a potassium ion, or a lithium ion, or an ammonium ion. The cationic group is preferably a quaternary alkylammonium group, and the counter anion of the cationic group is preferably a halide ion, a p-toluenesulfonic acid ion, or the like.
[0041]
Hereinafter, preferred specific examples of the surfactant represented by the general formula (F) are illustrated, but the surfactant is not limited thereto.
[0042]
F-1 (ONa)₂OP-OC₃F₆-O-PO (ONa)₂
F-2 NaCOO-C₃F₆-COONa
F-3 (COONa)₂CH-OC₃F₆-O-CH (COONa)₂
F-4 (COONa)₂CHCONH-C₃F₆-NHCOCH (COONa)₂
F-5 KOOC-C₃F₆-COOK
F-6 NaO₃SC₃F₆-SO₃Na
F-7 NaO₃S-OC₃F₆-O-SO₃Na
F-8 NaO₃SC₃H₆OC₃F₆-OC₃H₆-SO₃Na
F-9 LiO₃SC₃F₆-SO₃Li
F-10 LiO₃S-OC₃F₆-O-SO₃Li
F-11 LiO₃SC₃H₆OC₃F₆-OC₃H₆-SO₃Li
F-12 HO-C₃F₆-OH
F-13 HO-C₃H₆OC₄F₉-OC₃H₆-OH
F-14 (C₂H₄OH)₃-O-HC₄F₈-OC (C₂H₄OH)₃
F-15 HO- (CF₃)₂C-OH
With respect to the method for synthesizing the surfactant represented by the general formula (F), JP-A-10-500950 and JP-A-11-504360 can be referred to.
[0043]
In order to incorporate the surfactant represented by the general formula (F) into the back layer, the surfactant may be added to any of the non-photosensitive layers constituting the back layer. May be added.
[0044]
The amount of the surfactant represented by the general formula (F) is 20 to 200 mg / m²And particularly preferably 50 to 150 mg / m²It is.
[0045]
Next, a non-photosensitive organic silver salt, a photosensitive silver halide, a reducing agent, a high contrast agent, a binder, a support and the like which can be generally used for the photothermographic material of the present invention will be described.
[0046]
(Non-photosensitive organic silver salt)
The photosensitive layer according to the present invention contains a non-photosensitive organic silver salt which is a reducible silver source (hereinafter, also simply referred to as an organic silver salt), and the organic silver salt contains a reducible silver ion source. Silver salts of organic acids and hetero organic acids are preferred, especially long-chain (10 to 30, preferably 5 to 25 carbon atoms) aliphatic carboxylic acids and nitrogen-containing heterocyclic carboxylic acids. Organic or inorganic silver salt complexes wherein the ligand has a total stability constant for silver ions of 4.0 to 10.0 are also useful. Examples of suitable silver salts are described in Research Disclosure Nos. 17029 and 29996, and include: For example, salts of organic acids (eg, salts of gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.); carboxyalkylthiourea salts of silver (eg, 1- (3-carboxypropyl) thiourea , 1- (3-carboxypropyl) -3,3-dimethylthiourea); silver complexes of polymer reaction products of aldehydes with hydroxy-substituted aromatic carboxylic acids (for example, aldehydes such as formaldehyde, acetaldehyde, butyraldehyde) And hydroxy-substituted acids such as salicylic acid, benzylic acid 3,5-dihydroxybenzoic acid, and 5,5-thiodisalicylic acid); silver salts or complexes of thiones (for example, 3- (2-carboxyethyl) -4-hydroxy) Methyl-4-thiazoline-2-thione and 3-carboxymethyl-4-methyl-4-thio Zoline-2-thione); a nitrogen acid selected from imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole; Complexes or salts with silver; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptides. Preferred silver sources are silver behenate, silver arachidate and / or silver stearate.
[0047]
The organic silver salt can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver, and is described in Japanese Patent Application Laid-Open No. 9-127643, a forward mixing method, a reverse mixing method, a simultaneous mixing method. A controlled double jet method or the like is preferably used. For example, after adding an alkali metal salt (eg, sodium hydroxide, potassium hydroxide, etc.) to an organic acid to produce an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate, etc.), a controlled double jet Thus, the above-mentioned soap and silver nitrate are added to produce organic silver salt crystals. At that time, silver halide grains may be mixed.
[0048]
The organic silver salt according to the invention preferably has an average particle size of 1 μm or less and is monodispersed. The average particle size of the organic silver salt refers to the diameter of a sphere equivalent to the volume of the organic silver salt particles when the organic silver salt particles are, for example, spherical, rod-shaped, or tabular particles. The average particle size is preferably 0.01 μm to 0.8 μm, particularly preferably 0.05 μm to 0.5 μm. The monodispersion has the same meaning as that of silver halide, and preferably has a monodispersity of 1 to 30. In the present invention, the organic silver salt is more preferably monodisperse particles having an average particle diameter of 1 μm or less. By setting the content in this range, an image having a high density can be obtained. Further, the organic silver salt preferably has tabular grains having 60% or more of the total organic silver. In the present invention, the tabular grains refer to those having an aspect ratio (abbreviated as AR) of 3 or more, which is a ratio between an average particle diameter and a thickness, which is represented by the following formula.
[0049]
AR = average particle size (μm) / thickness (μm)
It is preferable that such organic silver salt particles are preliminarily dispersed together with a binder, a surfactant and the like, if necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. For the preliminary dispersion, a general stirrer such as an anchor type or a propeller type, a high-speed rotation centrifugal radiation type stirrer (dissolver), and a high-speed rotation shear type stirrer (homomixer) can be used. Further, as the media dispersing machine, a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill as a medium stirring mill, an attritor, and other basket mills can be used. Various types can be used, such as a type that collides with a plug or the like, a type in which liquids are divided into a plurality of pieces and then collides with each other at high speed, and a type in which a thin orifice passes.
[0050]
In the apparatus used for dispersing the organic silver salt particles according to the present invention, it is preferable to use ceramics or diamond such as zirconia, alumina, silicon nitride, and boron nitride as a material of a member with which the organic silver particles are in contact. It is particularly preferable to use zirconia.
[0051]
The organic silver salt particles according to the invention preferably contain 0.01 mg to 0.5 mg of zirconium per gram of silver, particularly preferably 0.01 mg to 0.3 mg of zirconium. It is very preferable to optimize the binder concentration, the preliminary dispersion method, the operating conditions of the disperser, the number of times of dispersion, and the like in performing the above dispersion, as a method for obtaining the organic silver salt particles used in the present invention.
[0052]
(Photosensitive silver halide)
The photosensitive silver halide contained in the photosensitive layer according to the invention functions as an optical sensor. In the present invention, the photosensitive silver halide grains preferably have a small average grain size in order to suppress white turbidity after image formation and obtain good image quality. The average particle size is preferably 0.03 μm or less, more preferably in the range of 0.01 to 0.03 μm.
[0053]
The photosensitive silver halide grains used in the photothermographic material of the present invention are prepared at the same time as the preparation of the organic silver salt, or prepared by mixing the silver halide grains during the preparation of the organic silver salt, It is preferable to form silver halide grains in a state of being fused to the organic silver salt to obtain fine grains, so-called in-situ silver.
[0054]
The method for measuring the average grain size of the silver halide grains is as follows: an image is taken at a magnification of 50,000 with an electron microscope, the long side and the short side of each silver halide grain are measured, and 100 grains are measured and averaged. Is the average particle size. Here, the above grain size refers to the length of the edge of the silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. In the case of non-normal crystals, for example, in the case of spherical, rod-shaped, or tabular grains, it refers to the diameter of a sphere equivalent to the volume of silver halide grains. Further, the silver halide grains are preferably monodispersed. The term “monodispersion” as used herein means that the degree of monodispersion determined by the following equation is 40% or less. The particle size is more preferably 30% or less, particularly preferably 0.1 to 20%.
[0055]
Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100
The photosensitive silver halide grains according to the present invention preferably have an average particle diameter of 0.01 to 0.03 μm and are more preferably monodisperse grains. By setting the average particle diameter in this range, the graininess of an image is also improved. The shape of the silver halide grains is not particularly limited, but the proportion occupied by the Miller index [100] plane is preferably high, and this proportion is 50% or more, more preferably 70% or more, especially 80% or more. Is preferred. The ratio of the Miller index [100] plane is determined by T.M. using the dependence of the adsorption of the sensitizing dye on the [111] plane and the [100] plane. Tani; Imaging Sci. , 29, 165 (1985).
[0056]
Another preferred shape of the photosensitive silver halide grains is tabular grains. Tabular grains are those having an aspect ratio = r / h of 3 or more when the square root of the projected area is r μm and the vertical thickness is h μm. Among them, the aspect ratio is preferably 3 to 50. The particle size is preferably 0.03 μm or less, and more preferably 0.01 to 0.03 μm. These production methods are described in U.S. Pat. Nos. 5,264,337, 5,314,798, and 5,320,958, and can easily obtain desired tabular grains. Can be. When these tabular grains are used in the invention, the sharpness of an image is further improved.
[0057]
The composition of the photosensitive silver halide grains is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. The photographic emulsion used in the present invention is P.I. Chimie et Physique Photographique (Paul Montel, 1967) by Glafkides; F. Duffin, Photographic Emulsion Chemistry (published by The Focal Press, 1966); L. It can be prepared by the method described in Making and Coating Photographic Emulsion by Zelikman et al (published by The Focal Press, 1964).
[0058]
The photosensitive silver halide grains according to the present invention preferably contain an ion or complex ion of a metal belonging to Group 6 to Group 10 of the Periodic Table of the Elements for the purpose of improving and adjusting the illuminance failure. As the above metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable.
[0059]
The photosensitive silver halide grains can be desalted by washing with water by a method known in the art such as a noodle method or a flocculation method, but may or may not be desalted in the present invention.
[0060]
The photosensitive silver halide grains according to the present invention are preferably chemically sensitized. Preferred chemical sensitization methods include sulfur sensitization, selenium sensitization, tellurium sensitization, and noble metal sensitization such as gold compounds, platinum, palladium, and iridium compounds as well known in the art. A sensitization method can be used.
[0061]
The total amount of the photosensitive silver halide grains and the organic silver salt according to the present invention is 1 m in terms of silver in order to prevent devitrification of the photothermographic material.²The amount is preferably 0.3 to 2.2 g, more preferably 0.5 g to 1.5 g. With this range, a high-contrast image can be obtained. The amount of silver halide relative to the total amount of silver is 50% or less by mass, preferably 25% or less, more preferably 0.1 to 15%.
[0062]
The photosensitive silver halide grains according to the present invention have a maximum absorption of light at 350 to 450 μm, and need not particularly have a sensitizing dye, but may contain a sensitizing dye as needed.
[0063]
(Reducing agent)
The reducing agent according to the present invention is described in U.S. Pat. Nos. 3,770,448, 3,773,512, 3,593,863, etc., and Research Disclosure Nos. 17029 and 29963. You can use what you have. For example, the following are mentioned.
[0064]
Aminohydroxycycloalkenones (eg, 2-hydroxy-3-piperidino-2-cyclohexenone); aminoreductones esters (eg, piperidinohexose reductone monoacetate) as precursors of reducing agents; N- Hydroxyurea derivatives (e.g., Np-methylphenyl-N-hydroxyurea); hydrazones of aldehydes or ketones (e.g., anthracenaldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (E.g., hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (e.g., benzenesulfoxy) Sulfonamidoanilines (e.g., 4- (N-methanesulfonamido) aniline); 2-tetrazolylthiohydroquinones (e.g., 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone) Tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline); amide oximes; azines; combinations of aliphatic carboxylic acid arylhydrazides and ascorbic acid; combinations of polyhydroxybenzene and hydroxylamine; And / or hydrazine; hydroxanoic acids; combinations of azines and sulfonamidophenols; α-cyanophenylacetic acid derivatives; combinations of bis-β-naphthol and 1,3-dihydroxybenzene derivatives; 5-pyrazolones; Nol reducing agent; 2-phenylindane-1,3-dione and the like; chroman; 1,4-dihydropyridines (for example, 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine); bisphenols (Eg, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol, 2,2-bis (4-hydroxy-3-methyl) Phenyl) propane, 4,4-ethylidene-bis (2-t-butyl-6-methylphenol)), an ultraviolet-sensitive ascorbic acid derivative; a hindered phenol; a 3-pyrazolidone. Among them, particularly preferred reducing agents are hindered phenols. Examples of hindered phenols include compounds represented by the following general formula (A).
[0065]
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[0066]
In the formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms (for example, -C4H9, 2,4,4-trimethylpentyl), and R 'and R "are alkyl groups having 1 to 5 carbon atoms. Represents a group (eg, methyl, ethyl, t-butyl).
[0067]
Specific examples of the compound represented by the general formula (A) are shown below. However, the present invention is not limited to the following compounds.
[0068]
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[0069]
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[0070]
The amount of the reducing agent including the compound represented by the general formula (A) is preferably 1 × 10 5 per mol of silver.^-2-10 mol, especially 1 × 10^-2１．５1.5 mol. Within this range, at least two of the above-mentioned reducing agents may be used in combination.
[0071]
(High contrast agent)
Examples of the contrast agent according to the present invention include hydrazine compounds. For example, Research Disclosure Item 23515 (November 1983, P. 346) and references cited therein, as well as U.S. Pat. No. 4,080,207 No. 4,269,929, No. 4,276,364, No. 4,278,748, No. 4,385,108, No. 4,459,347, No. 4 No. 4,478,928, No. 4,560,638, No. 4,686,167, No. 4,912,016, No. 4,988,604, No. 4,994,365. Nos. 5,041,355 and 5,104,769, British Patent No. 2,011,391B, European Patent Nos. 217,310, 301,799, and 356,898. , JP Nos. 0-179834, 61-170733, 61-270744, 62-178246, 62-270948, 63-29751, 63-32538, 63-104407, 63-10447 No. 121838, No. 63-129337, No. 63-223744, No. 63-234244, No. 63-234245, No. 63-234246, No. 63-294552, No. 63-306438, No. 64-10233 JP-A-1-90439, JP-A-1-100530, JP-A-1-105941, JP-A-1-105943, JP-A-1-276128, JP-A-1-280747, JP-A-1-283548, JP-A-1-283549, 1-285940, 2-2541, 2-77057, 2-139538, 2- No. 96234, No. 2-196235, No. 2-198440, No. 2-198441, No. 2-198442, No. 2-2220042, No. 2-2211953, No. 2-221954, No. 2-285342 No. 2-285343, No. 2-289843, No. 2-302750, No. 2-304550, No. 3-376542, No. 3-54549, No. 3-125134, No. 3-184039, No. Nos. 3-240036, 3-240037, 3-259240, 3-280038, 3-282536, 4-511143, 4-56842, 4-84134, 2- 230233, 4-96053, 4-216544, 5-45761, 5-45762, 5-45763, 5-45 No. 764, No. 5-45765, No. 6-289524, No. 9-160164, etc., or those described in the specification or the like.
[0072]
Other than these, compounds represented by (Chemical Formula 1) described in JP-B-6-77138, specifically, compounds described on pages 3 and 4 of the same publication, and JP-B-6-93082 Specific examples of the compound represented by the general formula (1) described in the above (1) to (8) on pages 8 to 18 and the general formula (4) described in JP-A-6-23049. , (5) and (6), specifically, Compounds 4-1 to 4-10 described on pages 25 and 26 and Compound 5-1 described on pages 28 to 36 of the same publication. Compounds 6-1 to 6-7 described on pages 39 and 40, and compounds represented by general formulas (1) and (2) described in JP-A-6-289520. Specifically, compounds 1-1) to 1-17) and 2-1) described on pages 5 to 7 of the same publication, and JP-A-6-313936 are described. The compounds represented by (Chemical Formula 2) and (Chemical Formula 3) described above, specifically, the compounds described on pages 6 to 19 of the same publication, and represented by (Chemical Formula 1) described in JP-A-6-313951. Specifically, compounds described on pages 3 to 5 of the same publication, compounds represented by the general formula (I) described in JP-A-7-5610, and Compounds I-1 to I-38 described on pages 5 to 10 and compounds represented by general formula (II) described in JP-A-7-77783, specifically, pages 10 to 27 of the same publication And compounds represented by the general formula (H) and the general formula (Ha) described in JP-A-7-104426. The compounds described in Compounds H-1 to H-44 described on page 30 can be used.
[0073]
Still other toning agents are compounds described on pages 33 to 53 of JP-A-11-31637, more preferably the following compounds described on pages 21 to 14 of JP-A-12-298327. is there.
[0074]
Embedded image

[0075]
Embedded image

[0076]
Embedded image

[0077]
Embedded image

[0078]
〔binder〕
In the photosensitive layer according to the present invention, a binder is used for holding an organic silver salt, a photosensitive silver halide, a reducing agent and the like. The binder is transparent or translucent, generally colorless, and includes natural polymers and synthetic monopolymers and copolymers, and other film-forming media such as: gelatin, gum arabic, poly (vinyl alcohol), hydroxyethylcellulose, cellulose acetate, cellulose acetate. Butyrate, poly (vinylpyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene-maleic anhydride), copoly (styrene) -Acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (e.g., poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly ( PVC Isopropylidene), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and polyamides. The binder used in the photothermographic material of the present invention may be either a hydrophilic binder or a hydrophobic binder, but it is preferable to use a hydrophobic transparent binder in order to reduce fog after thermal development.
[0079]
Preferred binders include polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, polyester, polycarbonate, polyacrylic acid, polyurethane and the like. Among them, polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, and polyester are particularly preferably used. It is preferable to use a hydrophobic transparent binder as described above, but if necessary, an appropriate amount of a water-soluble resin or a water-dispersed resin (latex) can be used in combination.
[0080]
As a main solvent for dissolving or dispersing the hydrophobic transparent binder, an organic solvent is mainly used, for example, alcohols (methanol, ethanol, propanol), ketones (acetone, methyl ethyl ketone) dimethylformamide, dimethyl sulfoxide, methylcell Solvent or the like is preferably used, and if necessary, water of preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less may be contained.
[0081]
The content of the binder in the photosensitive layer is 1.5 to 10 g / m2 in order to increase the speed of thermal development.²It is preferable that More preferably, 1.7 to 8 g / m²It is. 1.5g / m²If it is less than 3, depending on the type of the binder resin, the density of the unexposed portion will increase significantly, and may not be usable. 10g / m²If the ratio exceeds the range, the developability may be reduced and the density may not be obtained depending on the type of the binder.
[0082]
These binders are used to protect the surface of the photosensitive layer and prevent abrasion, so that the protective layer is laminated on top of the photosensitive layer. Therefore, it can also be used as a back layer and a back protective layer.
[0083]
The binder used for the protective layer, the back layer, and the back protective layer, which are the non-photosensitive layers, may be the same as or different from the binder used for the photosensitive layer. For the non-photosensitive layer, an epoxy resin or an acrylic monomer curable by an active energy ray may be used as a layer forming binder.
[0084]
(Support)
The support used in the photothermographic material of the present invention may be a plastic film (for example, polyethylene terephthalate (PET), polycarbonate, or the like) in order to obtain a predetermined optical density after development processing and to prevent deformation of an image after development processing. Polyimide, nylon, cellulose triacetate, polyethylene naphthalate) are preferred. Among them, preferred supports include plastic supports containing polyethylene terephthalate and a styrene polymer having a syndiotactic structure. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.
[0085]
Alternatively, a heat-treated plastic support may be used. The plastics to be used include the above-mentioned plastics. The heat treatment of the support means a temperature at which the support is formed at a temperature higher than the glass transition point of the support by at least 30 ° C., preferably at least 35 ° C., before the photosensitive layer and the protective layer are applied. It is more preferable to heat at a temperature higher by 40 ° C. or more. However, heating to a temperature exceeding the melting point of the support impairs the uniformity of strength of the support and is not preferred.
[0086]
[Other materials]
The photothermographic material of the present invention preferably contains a matting agent in the photosensitive layer or the protective layer in order to prevent the photothermographic material from slipping and preventing the adhesion of fingerprints. The content of the matting agent is preferably 0.5 to 30% by mass based on all binders used. Further, it is preferable that a matting agent is contained in at least one of the back layer and the back protective layer of the non-photosensitive layer opposite to the photosensitive layer with the support interposed therebetween. It is preferable to contain the binder in the back layer and the back protective layer in a weight ratio of 0.5 to 40% based on all binders.
[0087]
As the matting agent, any material can be used irrespective of the regular or irregular shape as long as it satisfies the following physical properties. For example, amorphous silica, boron nitride, aluminum nitride, titanium dioxide, magnesium oxide, aluminum oxide, calcium oxide, hydroxyapatite, magnesium carbonate, barium sulfate, strontium sulfate, polymethyl methacrylate, polymethyl acrylate, polystyrene, polyacrylonitrile, cellulose There are acetate, cellulose propionate, silicone, Teflon (R) and the like. Further, a fine particle impregnated with wax or silicone oil to give a slipperiness to the fine particles, or a fine particle whose surface is modified with a silane coupling agent or a titanium coupling agent can be used. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a spherical shape. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere.
[0088]
The average particle size of the matting agent on the photosensitive layer side is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 8 μm. The average particle size of the matting agent used for the back layer and the back protective layer is preferably from 3.0 μm to 20 μm, more preferably from 4.0 to 15 μm.
[0089]
The photothermographic material of the present invention may contain various additives such as an antifoggant, a toning agent, a sensitizing dye, and a substance exhibiting supersensitization (hereinafter abbreviated as supersensitizer) in the photosensitive layer. May be added.
[0090]
Such antifoggants include compounds such as the compounds disclosed in U.S. Pat. Nos. 3,874,946 and 4,756,999, and -C (X₁) (X₂) (X₃) (Where X₁And X₂Represents a halogen atom, X₃Represents a hydrogen atom or a halogen atom), a heterocyclic compound having at least one substituent represented by JP-A-9-288328, JP-A-9-90550, and US Pat. No. 5,028,523. And the compounds disclosed in European Patent Nos. 600,587, 605,981 and 631,176 can be selected and used as appropriate.
[0091]
For the purpose of improving the silver tone after development, toning agents added to the photosensitive layer include imides (eg, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (eg, succinimide, 3-phenyl) -2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione); naphthalimides (for example, N-hydroxy-1,8-naphthalimide); cobalt complexes (for example, hexaminetriamine of cobalt) Fluoroacetates), mercaptans (eg, 3-mercapto-1,2,4-triazole); N- (aminomethyl) aryldicarboximides (eg, N- (dimethylaminomethyl) phthalimide); blocked pyrazoles , Isothiuronium ) Combinations of derivatives and certain photobleaches (eg, N, N'-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiocyanate) A combination of uronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole; a merocyanine dye (e.g., 3-ethyl-5-((3-ethyl-2-benzothiazolinylidene (benzothiazolyne) Nylidene))-1-methylethylidene) -2-thio-2,4-oxazolidinedione); phthalazinone, a phthalazinone derivative or a metal salt of these derivatives (eg, 4- (1-naphthyl) phthalazinone, 6-chlorophthala Dinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedi A combination of phthalazinone and a sulfinic acid derivative (for example, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); a combination of phthalazine + phthalic acid; phthalazine (addition of phthalazine) Phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and their anhydrides (e.g., phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid) Acid anhydrides); quinazolinediones, benzoxazines, naltoxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione) ); Pyrimidines and asymmetric- Triazines (eg, 2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (eg, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene ). Preferred toning agents include phthalazone and phthalazine. The color toning agent may be added to the protective layer as long as the object of the present invention is not hindered.
[0092]
As sensitizing dyes, for example, for an argon ion laser light source, JP-A-60-162247, JP-A-2-48635, U.S. Pat. No. 2,161,331, West German Patent 936,071 JP-A-50-62425, JP-A-54-18726, and JP-A-59-102229 disclose simple merocyanines and helium neon laser light sources described in JP-A-5-11389 and JP-A-5-11389. For the trinuclear cyanine dyes described in JP-A-7-287338, the merocyanines described in JP-A-7-287338, the LED light source and the infrared semiconductor laser light source, JP-B-48-42172, JP-B-51-9609, and Thiacarbocyanines described in JP-A-55-39818, JP-A-62-284343 and JP-A-2-105135; Examples of the conductor laser light source include tricarbocyanines described in JP-A-59-19032 and JP-A-60-80841, and JP-A-59-192242 and JP-A-3-67242. Dicarbocyanines containing a 4-quinoline nucleus described in the general formulas (IIIa) and (IIIb) described in the gazettes are advantageously selected. Further, when the wavelength of the infrared laser light source is 750 nm or more, more preferably 800 nm or more. In order to cope with a laser in such a wavelength range, Japanese Patent Application Laid-Open Nos. 4-182439 and 5-341432, and JP-B-6-52387. And sensitizing dyes described in JP-A Nos. 3-10931, U.S. Pat. No. 5,441,866, and JP-A-7-13295 are preferably used.
[0093]
Examples of supersensitizers include RD17643, JP-B-9-25500, JP-B43-4933, JP-A-59-19032, JP-A-59-192242, and JP-A-5-341432. Compounds can be selected and used at appropriate times.
[0094]
In the present invention, a heteroaromatic mercapto compound represented by the following general formula (M) and a disulfide compound represented by the general formula (Ma) that substantially produces the above-mentioned mercapto compound can be used.
[0095]
General formula (M) Ar-SM
General formula (Ma) Ar-SS-Ar
In the general formula (M), M represents a hydrogen atom or an alkali metal atom, and Ar represents a heteroaromatic ring or a condensed heteroaromatic ring having at least one nitrogen, sulfur, oxygen, selenium or tellurium atom. The heteroaromatic ring is preferably benzimidazole, naphthymidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, Pyridine, purine, quinoline or quinazoline. Ar in the general formula (Ma) has the same meaning as that in the general formula (M).
[0096]
The heteroaromatic ring includes, for example, a halogen atom (eg, Cl, Br, I), a hydroxy group, an amino group, a carboxyl group, an alkyl group (eg, one or more carbon atoms, preferably 1 to 4 carbon atoms). It can have a substituent selected from the group consisting of those having carbon atoms and alkoxy groups (for example, those having one or more carbon atoms, preferably those having 1 to 4 carbon atoms).
[0097]
In order to increase the sensitivity, it is more preferable to use an organic sulfur compound shown below as a supersensitizer.
[0098]
Embedded image

[0099]
Embedded image

[0100]
The supersensitizer according to the present invention is preferably used in the emulsion layer of the photosensitive layer containing the organic silver salt and the silver halide grains in an amount of 0.001 to 1.0 mol per mol of silver, particularly preferably 1 mol of silver. It is preferred to be in the range of 0.01 to 0.5 mole per mole.
[0101]
The photosensitive layer according to the present invention can contain a macrocyclic compound containing a hetero atom. A 9 or more-membered macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a hetero atom is preferable, a 12 to 24 membered ring is more preferable, and a 15 to 21 membered ring is more preferable. is there. As a typical compound, the following compound was synthesized by Pederson as a crown ether in 1967, and many compounds have been synthesized since its unique report. These compounds are C.I. J. Pederson, Journal of American chemical society vol. 86 (2495), 7017-7036 (1967); W. Gokel, S.M. H. Korzeniowski, "Macrocyclic polyether synthesis", Springer-Vergal, (1982) and the like.
[0102]
In the photosensitive layer according to the present invention, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, a coating aid and the like may be used in addition to the additives described above. As these additives and the other additives described above, compounds described in Research Disclosure Item 17029 (pp. 9-15, June 1978) are preferably used.
[0103]
In the present invention, a conductive compound such as a metal oxide and / or a conductive polymer is added to a constituent layer such as an undercoat layer, a back layer, or an intermediate layer between the photosensitive layer and the undercoat layer in order to improve the chargeability. Can be included.
[0104]
The protective layer laminated on the photosensitive layer according to the present invention is composed of a binder used for the photosensitive layer and additives optionally added. As an additive added to the protective layer, it is preferable to contain a filler for the purpose of preventing damage to the image after thermal development and ensuring transportability, and the content of the filler when the filler is added is preferably in the layer forming composition. It is preferably contained in an amount of 0.05 to 30% by mass.
[0105]
Further, the protective layer may contain a lubricant and an antistatic agent in order to improve slipperiness and chargeability. Examples of such a lubricant include fatty acids, fatty acid esters, fatty acid amides, polyoxyethylene, and polyoxyethylene. Examples include oxypropylene, (modified) silicone oil, (modified) silicone resin, fluororesin, carbon fluoride, wax, and the like. As the antistatic agent, a cationic surfactant, an anionic surfactant, Nonionic surfactants, polymeric antistatic agents, metal oxides, conductive polymers, and the like, such as "11290 Chemical Products", Chemical Daily, p. Compounds described in 875 to 876 and the like, compounds described in U.S. Pat. No. 5,244,773, columns 14 to 20, and the like can be mentioned.
[0106]
The protective layer may be a single layer or a plurality of layers having the same or different compositions. In addition, the thickness of the protective layer is preferably 1.0 to 5.0 μm. Further, in addition to the photosensitive layer, the support and the protective layer, an intermediate layer may be provided in order to improve the film formation between the support and the photosensitive layer. 2.0 μm.
[0107]
The back layer according to the present invention may be a single layer or a plurality of layers having the same or different compositions. In addition, the thickness of the back layer is preferably 0.1 to 10 μm.
[0108]
The photothermographic material of the present invention has a filter dye layer on the same side as the photosensitive layer and / or an antihalation dye layer, a so-called back layer, on the opposite side to control the amount or wavelength distribution of light passing through the photosensitive layer. The photosensitive layer may contain a dye or a pigment.
[0109]
The protective layer of the photothermographic material of the present invention may further contain a slip agent such as a polysiloxane compound, wax or liquid paraffin, in addition to the binder and the matting agent.
[0110]
In the photothermographic material of the present invention, various surfactants are used as coating aids in each layer constituting the photothermographic material, and among them, fluorine-based surfactants improve the charging characteristics, It is preferably used in order to prevent a coating failure of the shape.
[0111]
The photosensitive layer according to the present invention may be composed of a plurality of layers, or may be composed of a high-sensitivity layer / low-sensitivity layer or a low-sensitivity layer / high-sensitivity layer for adjusting the gradation.
[0112]
In the photothermographic material of the present invention, the color toning agents disclosed in Research Disclosure No. 17029 can be used.
[0113]
In the photothermographic material of the present invention, to control thermal development by suppressing or promoting thermal development, to improve spectral sensitization efficiency, to improve the storage stability before and after development, such as a mercapto compound, a disulfide compound, A thione compound can be contained.
[0114]
An antifoggant may be used in the photothermographic material of the present invention, and these additives may be added to either the photosensitive layer or the non-photosensitive layer.
[0115]
The photothermographic material of the invention may contain, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, a coating aid, and the like. As these additives and the other additives described above, compounds described in Research Disclosure Item 17029 (pp. 9 to 15, June 1978) can be preferably used.
[0116]
An alkoxysilane compound having a secondary or tertiary amino group and polyethyleneimine are added to a photosensitive layer constituting the photothermographic material or a protective layer laminated on the photosensitive layer, and a back layer or a back protective layer. There is no particular limitation on the method of adding the compound, and the necessary amount may be added to the coating solution as it is, or may be diluted with an appropriate solvent and added to the coating solution as needed.
[0117]
The coating solution for the photosensitive layer according to the present invention, the coating solution for the protective layer, and the coating solution for the intermediate layer and the back layer, which are installed as necessary, dissolve each of the additives described above in a solvent. Alternatively, it can be prepared by dispersion.
[0118]
The solvent may be any solvent having a solubility parameter value in the range of 6.0 to 15.0 shown in "Solvent Pocket Book" edited by The Society of Synthetic Organic Chemistry of Japan. Examples of the solvent used for the coating liquid include acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, and methyl isobutyl ketone as ketones. Examples of the alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol. Glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, hexylene glycol and the like. Examples of ether alcohols include ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and the like. Examples of ethers include ethyl ether, dioxane, and isopropyl ether.
[0119]
Examples of the esters include ethyl acetate, butyl acetate, amyl acetate, and isopropyl acetate. Examples of the hydrocarbons include n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene, xylene and the like. Examples of the chlorides include methyl chloride, methylene chloride, chloroform, dichlorobenzene, and the like, but are not limited thereto as long as the effects of the present invention are not impaired.
[0120]
These solvents can be used alone or in combination of several kinds. The content of the solvent in the image forming material can be adjusted by changing conditions such as temperature conditions in a drying step after the coating step, and the total amount of the residual solvent contained in the photothermographic material is 5 to 5. 1000mg / m²Is more preferable, and more preferably, 10 to 300 mg / m²It is.
[0121]
When dispersion is necessary when forming a coating liquid, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a kobol mill, a tron mill, a sand mill, a sand grinder, a Sqegvari attritor, a high-speed impeller disperser, a high-speed stone mill, A conventionally known dispersing machine such as a high-speed impact mill, a disper, a high-speed mixer, a homogenizer, an ultrasonic dispersing machine, an open kneader, a continuous kneader, or the like can be appropriately selected and used.
[0122]
To apply the coating solution prepared as described above, an extrusion-type extrusion coater, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater Various known coater stations such as a transfer roll coater, a kiss coater, a cast coater, and a spray coater can be appropriately selected and used. Among these coaters, it is preferable to use a roll coater such as an extrusion extrusion coater or a reverse roll coater in order to eliminate thickness unevenness of the layer.
[0123]
The coating and drying may be repeated for each layer, or may be performed by multi-layer coating by a wet-on-wet method and dried. In this case, a reverse roll coater, a gravure roll coater, an air doctor coater, a blade coater, an air knife coater, a squeeze coater, an impregnation coater, a bar coater, a transfer roll coater, a kiss coater, a cast coater, a spray coater, etc. and an extrusion type extrusion coater are used. In the multi-layer coating in such a wet-on-wet method, the upper layer is applied while the lower layer remains wet, so that the adhesiveness between the upper and lower layers is improved. .
[0124]
In the present invention, the temperature at which the coating film is dried is preferably in the range of 65 to 100 ° C. in order to effectively bring out the purpose of the present invention after coating the photosensitive layer forming coating liquid. When the drying temperature is lower than 65 ° C., the reaction is insufficient and the sensitivity may fluctuate over time. When the drying temperature is higher than 100 ° C., the photothermographic material itself immediately after production is fogged. (Coloring) may occur, which is not preferable. The drying time cannot be specified unconditionally depending on the air volume at the time of drying, but it is usually preferable to dry in the range of 2 to 30 minutes. The drying temperature may be dried at a drying temperature in the above-mentioned temperature range immediately after coating, or the Marangoni of the coating liquid generated at the time of drying, or the vicinity of the surface generated by the drying air of the hot air is initially dried. For the purpose of preventing unevenness (yuzu skin) caused by the occurrence, drying may be performed at an initial drying temperature lower than 65 ° C., and thereafter, drying may be performed at a drying temperature in the above-described temperature range.
[0125]
The photothermographic material of the invention may have a moisture-proof layer and a moisture-retaining layer. The moisture-proof layer has a water vapor transmission rate of 0.005 g / m.²0.1 g / m or more²Refers to: Regarding moisture proof, there is no problem even if the water vapor transmission rate is low, but the upper limit is 0.1 g / m.²Otherwise, the effect of the moisture-proof layer is difficult to obtain. The moisturizing layer refers to a layer having a water absorption of 0.5% or more and 100% or less. If the water absorption is not 0.5% or more, no moisturizing effect can be obtained, so that improvement of the image performance under low humidity cannot be expected. If it is not 100% or less, the water content becomes too large and the fog worsens. Cause. The material used for the moisture-proof layer and the moisture-retaining layer is not particularly limited.
[0126]
Preferred materials used for the moisture-proof layer include polyvinyl alcohol, polyvinylidene chloride, polyolefin, polyfluorinated ethylene, polyfluoroethylene chloride, polyvinyl fluoride, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, chlorinated polyvinyl chloride, Examples thereof include polyacrylonitrile, rubber hydrochloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride-isobutylene copolymer, and vinyl chloride-diethyl fumarate copolymer.
[0127]
As a main solvent for dissolving or dispersing the binder, an organic solvent is mainly used in addition to water, for example, alcohols (methanol, ethanol, propanol), ketones (acetone, methyl ethyl ketone) dimethylformamide, dimethyl sulfoxide, Methyl cellosolve and the like are preferably used.
[0128]
Preferred materials used for the moisturizing layer include methyl methacrylate, cellulose resin, polyethylene resin, polyamide, olefin vinyl alcohol copolymer, ethylene vinyl acetate copolymer resin, and the like.
[0129]
As a main solvent for dissolving or dispersing the binder, an organic solvent is mainly used in addition to water, as described above. For example, alcohols (methanol, ethanol, propanol), ketones (acetone, methyl ethyl ketone) dimethylformamide , Dimethylsulfoxide, methylcellosolve and the like are preferably used.
[0130]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto.
[0131]
Example 1
<Preparation of Subbed PET Support 1>
Plasma treatment 1 is performed on both sides of a PET film having a thickness of 125 μm, a width of 1000 mm, and a length of 2000 m which has been biaxially stretched and heat-fixed by Teijin Limited under the following conditions, and then the following undercoating is applied to one surface The solution a-1 was applied to a dry film thickness of 0.8 μm and dried to form an undercoat layer A-1, and the following antistatic undercoat coating solution b-1 on the opposite side was dried. Coating was performed so as to have a thickness of 0.8 μm, and the coating was dried to obtain an antistatic subbing layer B-1. Next, the surface of each undercoat layer was subjected to plasma treatment 2 under the following conditions.
[0132]
<< Plasma treatment 1 and 2 conditions >>
Using a batch type atmospheric pressure plasma processing apparatus (AP-I-H-340, manufactured by EC Chemical Co., Ltd.), high-frequency output was 4.5 kW, frequency was 5 kHz, processing time was 5 seconds, and argon was used as a gas condition. The runs were performed at 90%, 5% and 5% by volume of nitrogen and hydrogen, respectively.
[0133]

《Heat treatment of support》
In the undercoat drying step of the undercoated support described above, the support was heated at 140 ° C. and then gradually cooled. 1 × 10⁵It was transported at a tension of Pa.
[0134]
《Coating on back layer side》
The back layer coating solution and the back protective layer coating solution having the following compositions were respectively filtered using a filter having a quasi-absolute filtration accuracy of 20 μm before coating, and then subjected to an antistatic treatment of the support prepared by an extrusion coater. On the B-1 surface, simultaneous multi-layer coating was performed at a rate of 120 m / min so that the total wet film thickness became 30 μm, and a subbed PET support 1 was obtained.
[0135]

In Table 1, the comparative compound 1 in the column of the surfactant represented by the general formula (F) refers to C₈F₁₇SO₃Li.
[0136]
<Preparation of photosensitive layer>
<< Preparation of photosensitive silver halide emulsion B >>
A1
Phenylcarbamoyl gelatin 88.3g
Compound (A) (10% methanol solution) 10 ml
Potassium bromide 0.32g
Finish to 5429ml with water
B1
0.67M / L silver nitrate aqueous solution 2635ml
C1
Potassium bromide 51.55 g
1.47 g of potassium iodide
Finish to 660ml with water
D1
Potassium bromide 154.9g
4.41 g of potassium iodide
0.93 ml of iridium chloride (1% solution)
E1
0.4M / L potassium bromide aqueous solution The following silver potential control amount
F1
56% acetic acid aqueous solution 16.0 ml
G1
1.72 g of anhydrous sodium carbonate
Finish to 151ml with water
Compound (A):
HO (CH₂CH₂O) n- [CH (CH₃) CH₂O]₁₇− (CH₂CH₂O)_mH m + n = 5-7
Using a mixing stirrer disclosed in JP-B-58-58288 and JP-B-58-58289, 1/4 of the solution B1 and the total amount of the solution C1 were added to the solution A1 at 45 ° C., and the silver potential (pAg) was 8. While controlling to 09, the addition was performed by a simultaneous mixing method in 4 minutes and 45 seconds to form nuclei.
[0137]
After a lapse of 7 minutes, the remainder of the solution B1 and the entire amount of the solution D1 were added over 14 minutes and 15 seconds by a double jet method while controlling the temperature at 45 ° C. and the pAg at 8.09. During the mixing, the pH of the reaction solution was 5.6.
[0138]
After stirring for 5 minutes, the temperature was lowered to 40 ° C., and the whole amount of the solution F1 was added to precipitate a silver halide emulsion. The supernatant liquid was removed, leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The supernatant was removed except for the sedimented portion of 1500 ml, and 10 L of water was further added. After stirring, the silver halide emulsion was sedimented. After removing the supernatant liquid leaving 1500 ml of the sedimented portion, the solution G1 was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount became 1161 g per mole of silver, whereby photosensitive silver halide emulsion B was obtained. The silver halide grains of the resulting photosensitive silver halide emulsion B are cubic silver iodobromide grains having an average grain size of 0.058 μm, a coefficient of variation in grain size of 12%, and a [100] face ratio of 92%. Was.
[0139]
<< Preparation of powdered organic silver salt B >>
130.8 g of behenic acid, 67.7 g of arachidic acid, 43.6 g of stearic acid and 2.3 g of palmitic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 M / L aqueous sodium hydroxide solution was added, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a fatty acid sodium solution. While maintaining the temperature of the above-mentioned sodium fatty acid solution at 55 ° C., 31.7 g of the above-mentioned photosensitive silver halide emulsion B and 465 ml of pure water were added and stirred for 5 minutes.
[0140]
Next, 702.6 ml of a 1 M / L silver nitrate solution was added over 2 minutes and stirred for 10 minutes to obtain an organic silver salt dispersion. Thereafter, the obtained organic silver salt dispersion was transferred to a water washing container, deionized water was added thereto, and the mixture was stirred and allowed to stand. Then, the organic silver salt dispersion was floated and separated, and the lower water-soluble salts were removed. After that, washing with deionized water and draining are repeated until the conductivity of the waste water becomes 2 μS / cm, and centrifugal dehydration is performed. Drying was performed until the water content became 0.1% under the operating conditions of an inlet hot air temperature of 75 ° C. to obtain a powdered organic silver salt B. At this time, the dry hot air used was heated air in the atmosphere with an electric heater. An infrared moisture meter was used for measuring the water content of the powdered organic silver salt B.
[0141]
<< Preparation of Preliminary Dispersion B >>
14.57 g of polyvinyl butyral powder “Butvar B-79” (manufactured by Monsanto) is dissolved in 1457 g of methyl ethyl ketone (hereinafter abbreviated as MEK), and the powder is stirred with a “Dissolver DISPERMAT CA-40M Model Stirrer” manufactured by VMA-GETZMANN. Preliminary dispersion liquid B was prepared by gradually adding 500 g of organic silver salt B and mixing well.
[0142]
<< Preparation of photosensitive emulsion dispersion B >>
Dispersmat SL-C12EX media disperser filled with zirconia beads (Toray Torayceram) having a diameter of 0.5 mm and having an inner volume of 80% so that the pre-dispersion liquid B is kept in the mill for 10 minutes using a pump. (Manufactured by VMA-GETZMANN) and dispersed at a mill peripheral speed of 13 m / s to prepare a photosensitive emulsion dispersion B.
[0143]
<< Preparation of Solution d >>
A solution d was prepared by dissolving 0.1 g of the compound P and 0.1 g of the compound Q in 10.1 g of methanol.
[0144]
<< Preparation of Sensitizing Dye Liquid a >>
29 mg of sensitizing dye 1, 4.5 g of 2-chloro-benzoic acid, 8.4 g of solution d and 280 mg of 5-methyl-2-mercaptobenzimidazole were dissolved and dissolved in 77.2 ml of MEK in the dark. Dye-sensitive solution a was prepared.
[0145]
<< Preparation of additive liquid a >>
107 g of a reducing agent (exemplified compound A-4) and 4.8 g of 4-methylphthalic acid were dissolved in 261 g of MEK to prepare an additive solution a.
[0146]
<< Preparation of additive liquid b >>
11.6 g of the antifoggant 2 was dissolved in 137 g of MEK to prepare an additive liquid b.
[0147]
<< Preparation of additive liquid c >>
21.7 g of alkoxysilane compound: C₆H₅-NH- (CH₂) -Si- (OCH₃)₃And 45 g of the antifoggant 3 were dissolved in 159 g of MEK to obtain an additive liquid c.
[0148]
<< Preparation of additive liquid d >>
1m²Phthalazine in an amount of 0.17g per 1m²The solution was dissolved in MEK in an amount of 2.73 g per solution to obtain an additive liquid d.
[0149]
<< Preparation of photosensitive layer coating solution E-1 >>
The photosensitive emulsion dispersion B (1641 g) and 506 g of MEK were kept at 21 ° C. while stirring, 10.75 g of antifoggant 1 (11.2% methanol solution) was added, and the mixture was stirred for 1 hour. Further, 13.6 g of calcium bromide (11.2% methanol solution) was added and stirred for 20 minutes. Subsequently, after adding 1.3 g of the solution d and stirring for 10 minutes, the sensitizing dye solution a was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes. While keeping the temperature at 13 ° C., 349.6 g of polyvinyl butyral “Butvar B-79” (manufactured by Monsanto) was added, and the mixture was stirred for 30 minutes. Then, 95 mg of 5-methyl-2-mercaptobenzimidazole and 95 mg of tetrachlorophthalic acid 3 were added. 0.5 g was added and stirred for 30 minutes. Thereafter, 1.2 g of 5-nitroindazole, 0.4 g of 5-nitrobenzimidazole, 3.0 g of a toning agent C-62 (vinyl compound) and 225 g of MEK were added. While further stirring, 148.6 g of each of the additional liquid a, the additional liquid b, and the additional liquid d, and 225 g of the additional liquid c were sequentially added and stirred to obtain a photosensitive layer coating liquid E-1.
[0150]
<< Preparation of protective layer coating solution >>
1m²While stirring 30 g of MEK per unit, 3.5 g of cellulose acetate butyrate (manufactured by Eastman Chemical Company, CAB171-15): 3.5 g, polymethylmethacrylic acid (manufactured by Rohm & Haas Company, paraloid A-21): 160 mg, benzotriazole: 35 mg, Fluorosurfactant F-1: C₈F₁₇SO₃20 mg of Li, fluorinated surfactant F-2: C₈F₁₇(CH₂CH₂O)₂₂C₈F₁₇Was added and dissolved. Next, 3.5 g of the following matting agent dispersion was added and stirred to prepare a protective layer coating solution.
[0151]
<< Preparation of matting agent dispersion >>
1m²To 1.7 g of MEK, 50 mg of monodispersed silica having an average particle size of 3 μm was added, and dispersed with a dissolver-type homogenizer at 8000 rpm for 30 minutes to prepare a matting agent dispersion.
[0152]
Embedded image

[0153]
《Coating on photosensitive layer side》
The photosensitive layer and the protective layer were applied in this order on the undercoated PET support 1 described above. The photosensitive layer coating solution E-1 and the protective layer coating solution were filtered through a filter having an absolute filtration accuracy of 20 μm, and then, using an extrusion die coater, a subbing layer A-1 of the subbed PET support 1. Each layer was sequentially coated on the film at a speed of 60 m / min.
[0154]
The photosensitive layer was coated, 8 seconds later, dried with hot air at a drying temperature of 75 ° C. and a dew point of 10 ° C. for 5 minutes, and then wound up in a roll to obtain a photothermographic material.
[0155]
The coated silver amount of the photosensitive layer of the obtained photothermographic material is 1.5 g / m2.²The dry thickness of the surface protective layer was 2.5 μm.
[0156]
《Evaluation》
After leaving each of the prepared samples in an environment of 23 ° C., 20% RH, and 23 ° C., 80% RH for 8 hours, wedge exposure was performed, and after thermal development processing, maximum density (Dmax) and minimum density (Dmax) were evaluated as image evaluation Dmin) are shown in Table 1.
[0157]
In the exposure and development processes for evaluating the maximum density (Dmax) and the minimum density (Dmin), each sample was cut into 25 cm × 30 cm and exposed through a wedge using a sensitometer having a 780 nm semiconductor laser. Development was carried out using a film processor model 2771 manufactured by Imation Co., Ltd. at 120 ° C. for 48 seconds. At that time, exposure was performed in a room conditioned at 23 ° C. and 50% RH, and development processing was performed in an environment of 23 ° C., 20% RH, and 23 ° C., 80% RH, respectively.
[0158]
<Evaluation of Dmax and Dmin>
For Dmax and Dmin, visual densities of the Dmax part and the Dmin part of each sample after the heat development were measured using an optical densitometer (manufactured by X-rite), and were evaluated according to the following evaluation ranks.
[0159]
Regarding Dmax, a value of 4.0 or more was judged as acceptable, and a value of less than 4.0 was judged as unacceptable. Regarding Dmin, it was determined that the pass was less than 0.11 and the reject was not more than 0.11.
[0160]
[Table 1]

[0161]
Table 1 shows that all the samples of the present invention exhibited excellent performance.
[0162]
【The invention's effect】
According to the present invention, it has been possible to provide a photothermographic material which suppresses an increase in fog and a change in gradation during storage of the photothermographic material before use.

Claims (2)

A support having a photosensitive layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, a contrasting agent and a binder, and at least one back layer on the side of the support opposite to the photosensitive layer. In the photothermographic material having
A photothermographic material, wherein the back layer contains a compound that reacts with formic acid and a surfactant represented by the following general formula (F).
General formula (F) X- (L) _m -Rf- (L ') _m -X'
[Wherein, Rf represents an aliphatic group having at least one fluorine atom, L and L ′ represent a simple bond or a divalent linking group, m represents 0 or an integer of 1 to 5, X and X ′ represents a hydrogen atom, a hydroxyl group, an anionic group or a cationic group. ] The photothermographic material according to claim 1, wherein the compound that reacts with formic acid is a compound represented by the following general formula (1).
General formula (1) R-NH ₂
[In the formula, R represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, an alkylamino group or an arylamino group, each of which may have a substituent. ]