JP4244541B2 - Photothermographic imaging material with excellent charging characteristics - Google Patents

Description

【００２５】
【化４】

【００２６】
本発明の一般式（１）で表されるπ電子導電性ポリマーを添加する方法としては、微粒子分散して添加する方法が好ましい。
【００２７】
微粒子分散する方法としては、ガラスビーズやジルコニア微粒子メディアを使用するサンドミル分散法、細管から溶液を高速に噴出させて硬い板状で砕いたり、２方向からの細管の液体を衝突させて分散させる方法等が挙げられる。微粒子分散径は、水溶液中にて平均粒子径０．０１μｍ〜１０μｍの大きさが好ましく、また粒径分布が狭いことが好ましい。平均粒子径が０．０１μｍ未満では微粒子化するのに時間が掛かる等生産性が劣化することがある。また、１０μｍを越えると微粒子の粒径分布が広がり凝集が発生することがある。
【００２８】
別の添加方法としては、水、アルコール類（例えば、メタノール、エタノール、イソブチルアルコール等）、ケトン類（例えば、アセトン、メチルエチルケトン、イソブチルケトン等）、芳香族有機溶媒類（例えば、トルエン、キシレン等）等に溶解して添加することができる。
【００２９】
次に、本発明の一般式（２）で表されるフッ素系界面活性剤について説明する。
【００３０】
前記一般式（２）において、Ｒｆはフッ素原子を含有する置換基を表すが、該フッ素原子を含有する置換基としては例えば、炭素数１〜２５のアルキル基（例えば、メチル基、エチル基、ブチル基、オクチル基、ドデシル基およびオクタデシル基等）またはアルケニル基（例えば、プロペニル基、ブテニル基、ノネニル基およびドデセニル基等）等が挙げられる。
【００３１】
Ｌ₁はフッ素原子を有さない２価の連結基を表すが、該フッ素原子を有さない２価の連結基としては例えば、アルキレン基（例えば、メチレン基、エチレン基、ブチレン基等）、アルキレンオキシ基（メチレンオキシ基、エチレンオキシ基、ブチレンオキシ基等）、オキシアルキレン基（例えば、オキシメチレン基、オキシエチレン基、オキシブチレン基等）、オキシアルキレンオキシ基（例えば、オキシメチレンオキシ基、オキシエチレンオキシ基、オキシエチレンオキシエチレンオキシ基等）、フェニレン基、オキシフェニレン基、フェニルオキシ基、オキシフェニルオキシ基またはこれらの基を組み合わせた基等が挙げられる。
【００３２】
Ａはアニオン基またはその塩基を表すが、例えば、カルボン酸基またはその塩基（ナトリウム塩、カリウム塩およびリチウム塩）、スルホン酸基またはその塩基（ナトリウム塩、カリウム塩およびリチウム塩）および燐酸基またはその塩基（ナトリウム塩およびカリウム塩等）等が挙げられる。
【００３３】
Ｙはフッ素原子を有さない３価または４価の連結基を表すが、例えば、フッ素原子を有さない３価または４価の連結基で炭素原子または窒素原子を中心にして構成される原子群が挙げられる。ｐは１〜３の整数を表し、ｑは２〜３の整数を表す。
【００３４】
一般式（２）で表されるフッ素系界面活性剤は、フッ素原子を導入した炭素数１〜２５のアルキル化合物（例えば、トリフロロメチル基、ペンタフロロエチル基、パーフロロブチル基、パーフロロオクチル基およびパーフロロオクタデシル基等を有する化合物）およびアルケニル化合物（例えば、パーフロロヘキセニル基およびパーフロロノネニル基等）と、それぞれフッ素原子を導入していない３価〜６価のアルカノール化合物、水酸基を３〜４個有する芳香族化合物またはヘテロ化合物との付加反応や縮合反応によって得られた化合物（一部Ｒｆ化されたアルカノール化合物）に、更に例えば硫酸エステル化等によりアニオン基（Ａ）を導入することにより得ることができる。
【００３５】
上記３〜６価のアルカノール化合物としては、グリセリン、ペンタエリスリトール、２−メチル−２−ヒドロキシメチル１，３−プロパンジオール、２，４−ジヒドロキシ−３−ヒドロキシメチルペンテン、１，２，６−ヘキサントリオール、１，１，１−トリス（ヒドロキシメチル）プロパン、２，２−ビス（ブタノール）−３、脂肪族トリオール、テトラメチロールメタン、Ｄ−ソルビトール、キシリトール、Ｄ−マンニトール等が挙げられる。
【００３６】
また、上記水酸基を３〜４個有する芳香族化合物およびへテロ化合物としては、１，３，５−トリヒドロキシベンゼンおよび２，４，６−トリヒドロキシピリジン等が挙げられる。
【００３７】
以下に、一般式（２）で表されるフッ素系界面活性剤の好ましい具体的化合物を示す。
【００３８】
【化５】

【００３９】
【化６】

【００４０】
本発明の一般式（２）で表されるフッ素系界面活性剤を塗布液に添加する方法としては公知の添加法に従って添加することができる。即ち、メタノールやエタノール等のアルコール類、メチルエチルケトンやアセトン等のケトン類、ジメチルスルホキシドやジメチルホルムアミド等の極性溶媒等に溶解して添加することができる。又、サンドミル分散やジェットミル分散、超音波分散やホモジナイザー分散により１μｍ以下の微粒子にして水や有機溶媒に分散して添加することもできる。微粒子分散技術については多くの技術が開示されているが、これらに準じて分散することができる。一般式（２）で表されるフッ素系界面活性剤は、最外層の保護層に添加することが好ましい。
【００４１】
本発明の一般式（２）で表されるフッ素系界面活性剤の添加量は１ｍ²当たり１×１０^-8〜１×１０^-1モルが好ましく、１×１０^-5〜１×１０^-2モルが特に好ましい。前者の範囲未満では、帯電特性が得られず、前者の範囲を越えると、湿度依存性が大きく高湿下の保存性が劣化する。
（結合剤）
結合剤としては、ポリビニルアルコール誘導体（ポリアセタールを含む）、メタクリレートポリマー誘導体、アクリレートポリマー誘導体、ポリイミド誘導体、ポリアミド誘導体、フェノール樹脂誘導体、ウレタン樹脂誘導体およびポリエステル誘導体等が挙げられる。特に好ましい誘導体はポリビニルアルコール誘導体あるいは酢酸ビニル誘導体である。
（結合剤に使用する架橋剤）
結合剤は、単独で造膜することにより、下層や上層との接着を保持し、傷の付きにくい膜強度を得ることができるが、架橋剤を使用することにより更に膜接着を高めることができる。しかし、架橋反応が遅いと、写真性能が安定せず保存性が劣化する。本発明に使用される即効性で、好ましい架橋剤としてはイソシアナート基、エポキシ基、またはビニルスルホニル基のいずれかを少なくとも２個有する多官能型架橋剤、あるいはアルコキシシラン基を少なくとも１個有するアルコキシシラン化合物を挙げることができる。
【００４２】
本発明に用いられる好ましい架橋剤の具体例を下記に示す。
（Ｈ１） ヘキサメチレンジイソシアナート
（Ｈ２） ヘキサメチレンジイソシアナートの３量体
（Ｈ３） トリレンジイソシアナート
（Ｈ４） フェニレンジイソシアナート
（Ｈ５） キシリレンジイソシアナート
上記架橋剤は、水、アルコール類、ケトン類、非極性の有機溶媒類に溶解して添加してもよいし、塗布液中に固形のまま添加してもよい。添加量は、結合剤の架橋する基と当量が好ましいが、１０倍まで増量してもよいし、１０分の１以下まで減量してもよい。上記よりも少なすぎると架橋反応が進まないし、上記よりも多すぎると未反応の架橋剤が写真性を劣化させるので好ましくない。
（ハロゲン化銀粒子）
本発明の光熱写真画像形成材料に使用される感光性ハロゲン化銀は、シングルジェットもしくはダブルジェット法などの写真技術の分野で公知の方法により調製でき、例えば、アンモニア法乳剤、中性法、酸性法等のいずれかの方法でも調製できる。
【００４３】
ハロゲン化銀は、画像形成後の白濁（ヘイズ）を低く抑えるため、又、良好な画質を得るために粒子サイズが小さいものが好ましい。平均粒子サイズで通常１００ｎｍ以下、好ましくは１０ｎｍ〜６０ｎｍ、特に２０ｎｍ〜５０ｎｍが好ましい。又、ハロゲン化銀の形状としては特に制限はなく、立方体、八面体の謂ゆる正常晶や正常晶でない球状、棒状、平板状等の粒子が挙げられる。又ハロゲン化銀組成としても特に制限はなく、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。
【００４４】
ハロゲン化銀の量はハロゲン化銀及び後述の有機銀塩の総量に対し通常５０％以下であり、好ましくは２５％〜０．１％、更に好ましくは１５％〜０．１％の間である。
【００４５】
本発明の光熱写真画像形成材料に使用される感光性ハロゲン化銀は又、英国特許第１，４４７，４５４号明細書に記載されている様に、有機銀塩を調製する際にハライドイオン等のハロゲン成分を有機銀塩形成成分と共存させこれに銀イオンを注入することで有機銀塩の生成とほぼ同時に生成させることができる。
【００４６】
更に他の方法としては、予め調製された有機銀塩の溶液もしくは分散液、又は有機銀塩を含むシート材料にハロゲン化銀形成成分を作用させて、有機銀塩の一部を感光性ハロゲン化銀に変換することもできる。このようにして形成されたハロゲン化銀は有機銀塩と有効に接触しており好ましい作用を呈する。
【００４７】
これらの感光性ハロゲン化銀には、照度不軌や、階調調整のために元素周期律表の６族から１１族に属する金属、例えばＲｈ、Ｒｕ、Ｒｅ、Ｉｒ、Ｏｓ、Ｆｅ等のイオン、その錯体又は錯イオンをドープ（含有）させることができる。これらの金属イオンは金属塩をそのままハロゲン化銀に導入してもよいが、金属錯体又は錯体イオンの形でハロゲン化銀に導入できる。これらの、遷移金属錯体及び金属錯体イオンとしては、６配位錯体イオンが好ましい。
【００４８】
配位子の具体例としては、ハロゲン化物（弗化物、塩化物、臭化物及び沃化物）、シアン化物、シアナート、チオシアナート、セレノシアナート、テルロシアナート、アジド及びアコの各配位子、ニトロシル、チオニトロシル等が挙げられ、好ましくはアコ、ニトロシル及びチオニトロシル等である。アコ配位子が存在する場合には、配位子の一つ又は二つを占めることが好ましい。
【００４９】
特に好ましいドープ金属原子の具体例としては、ロジウム（Ｒｈ）、ルテニウム（Ｒｕ）、レニウム（Ｒｅ）、イリジウム（Ｉｒ）及びオスミウム（Ｏｓ）である。これらの金属錯体又は錯体イオンは一種類でもよいし、同種の金属及び異種の金属を二種以上併用してもよい。
【００５０】
これらの金属のイオン、金属錯体及び錯体イオンの含有量としては、通常ハロゲン化銀１モル当たり１×１０^-9〜１×１０^-2モルが適当であり、好ましくは１×１０^-8〜１×１０^-4モルである。過度の添加量は感度の低下や軟調化、最高濃度の低下を引き起こすので好ましくない。これらの金属のイオン又は錯体イオンを提供する化合物は、ハロゲン化銀粒子形成時に添加し、ハロゲン化銀粒子中に組み込まれることが好ましく、ハロゲン化銀粒子の調製、つまり核形成、成長、物理熟成、化学増感の前後のどの段階で添加してもよいが、特に核形成、成長、物理熟成の段階で添加するのが好ましく、更には核形成、成長の段階で添加するのが好ましく、最も好ましくは核形成の段階で添加する。添加に際しては、数回に渡って分割して添加してもよく、ハロゲン化銀粒子中に均一に含有させることもできるし、特開昭６３−２９６０３号、特開平２−３０６２３６号、同３−１６７５４５号、同４−７６５３４号、同６−１１０１４６号、同５−２７３６８３号等に記載されている様に粒子内に分布を持たせて含有させることもできる。
【００５１】
これらの金属化合物は、水或いは適当な有機溶媒（例えば、アルコール類、エーテル類、グリコール類、ケトン類、エステル類、アミド類）に溶解して添加することができるが、他にも、例えば金属化合物の粉末の水溶液もしくは金属化合物とＮａＣｌ、ＫＣｌとを一緒に溶解した水溶液を、粒子形成中の水溶性銀塩溶液又は水溶性ハライド溶液中に添加しておく方法、或いは銀塩溶液とハライド溶液が同時に混合されるとき第３の水溶液として添加し、３液同時混合の方法でハロゲン化銀粒子を調製する方法、粒子形成中に必要量の金属化合物の水溶液を反応容器に投入する方法、或いはハロゲン化銀調製時に予め金属のイオン又は錯体イオンをドープしてある別のハロゲン化銀粒子を添加して溶解させる方法等により添加することもができる。
【００５２】
上記した各種の方法によって調製される感光性ハロゲン化銀は、例えば含硫黄化合物、金化合物、白金化合物、パラジウム化合物又はこれらの組み合わせによって化学増感することができる。化学増感の方法及び手順については、例えば米国特許第４，０３６，６５０号、英国特許第１，５１８，８５０号、特開昭５１−２２４３０号、同５１−７８３１９号、同５１−８１１２４号に記載されている。
【００５３】
本発明においては、感光層側にマット剤を含有することが好ましく、熱現像後の画像の傷つき防止のために、感光材料の表面にマット剤を配することが好ましい。マット剤を感光層側の全結合剤に対し、質量比で０．５〜３０％含有することが好ましい。
【００５４】
また、支持体をはさみ感光層の反対側に非感光層を設ける場合は、非感光層側の少なくとも１層中にマット剤を含有することが好ましく、感光材料のすべり性や指紋付着防止のためにも感光材料の表面にマット剤を配することが好ましい。マット剤を感光層側の反対側の層の全結合剤に対し、質量比で０．５〜４０％含有することが好ましい。
【００５５】
本発明において用いられるマット剤の材質は、有機物及び無機物のいずれでもよい。例えば、無機物としては、スイス特許第３３０，１５８号等に記載のシリカ、有機物としては、米国特許第２，３２２，０３７号等に記載の澱粉、ベルギー特許第６２５，４５１号や英国特許第９８１，１９８号等に記載された澱粉誘導体、特公昭４４−３６４３号等に記載のポリビニルアルコール、スイス特許第３３０，１５８号等に記載のポリスチレン或いはポリメタアクリレート、米国特許第３，０７９，２５７号等に記載のポリアクリロニトリル、米国特許第３，０２２，１６９号等に記載されたポリカーボネート等の有機マット剤を用いることができる。
【００５６】
マット剤の形状は、定形、不定形どちらでもよいが、好ましくは定形で、球形が好ましく用いられる。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。
【００５７】
本発明に用いられるマット剤は、平均粒径が０．５μｍ〜１０μｍであることが好ましく、更に好ましくは１．０μｍ〜８．０μｍである。又、粒子サイズ分布の変動係数（（粒径の標準偏差）／（粒径の平均値）×１００）としては、５０％以下であることが好ましく、更に、好ましくは４０％以下であり、特に好ましくは３０％以下である。
【００５８】
本発明に用いられるマット剤の添加方法は、予め塗布液中に分散させて塗布する方法であってもよいし、塗布液を塗布した後、乾燥が終了する以前にマット剤を噴霧する方法を用いてもよい。また複数の種類のマット剤を添加する場合は、両方の方法を併用してもよい。マット剤の添加量は、マット粒子の大きさによりヘイズの問題にならないレベルで適宜決定することができるが、０．０１ｍｇ／ｍ²〜１ｇ／ｍ²が好ましい。過度の添加は、ヘイズが問題となる。
（支持体）
支持体としては、ポリエチレンテレフタレート、ポリエチレンナフタレートまたはシンジオタクチックポリスチレン等の支持体が好ましく、２軸延伸や熱固定した光学的に等方性が高く、寸法安定性のよい５０μｍ〜４００μｍの厚さのものがよい。
（画像露光）
露光方法としては、特開平９−３０４８６９号、同９−３１１４０３号および特開２０００−１０２３０号記載の方法によりレーザー露光することができる。本発明の光熱写真画像形成材料の露光においては、感光材料に付与した感色性に対し適切な光源を用いることが望ましい。例えば、感光材料を赤外光に感じ得るものとした場合は、赤外光域ならば如何なる光源にも適用可能であるが、レーザーパワーがハイパワーであることや、感光材料を透明にできる等の点から、赤外半導体レーザー（７８０ｎｍ、８２０ｎｍ）がより好ましく用いられる。
（熱現像装置）
光熱写真画像形成材料を現像する装置としては、特開平１１−６５０６７号、同１１−７２８９７号および同１１−８４６１９号記載の装置を使用することができる。
【００５９】
【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。
【００６０】
実施例１
下塗り済み写真用支持体の作製
光学濃度で０．１７０に青色着色した市販の２軸延伸熱固定済みの厚さ１７５μｍのポリエチレンテレフタレートフィルムの両面にコロナ放電処理（８Ｗ／ｍ²・分）を施し、一方の面に下記下塗り塗布液ａ−１を塗設し乾燥させて下塗りＡ−１とし、また反対側の面に下記下塗り塗布液ｂ−１を塗設し乾燥させてバック層側下塗り層Ｂ−１とした。
下塗り塗布液ａ−１
ブチルアクリレート（３０質量％）
ｔ−ブチルアクリレート（２０質量％）
スチレン（２５質量％）
２−ヒドロキシエチルアクリレート（２５質量％）
の共重合体ラテックス液（固形分３０％） ０．０８ｇ／ｍ²
ヘキサメチレン−１，６−ビス（エチレンウレア） ０．００８ｇ／ｍ²
下塗り塗布液ｂ−１
ブチルアクリレート（４０質量％）
スチレン（２０質量％）
グリシジルアクリレート（４０質量％）
の共重合体ラテックス液（固形分３０％） ０．０８ｇ／ｍ²
ヘキサメチレン−１，６−ビス（エチレンウレア） ０．００８ｇ／ｍ²
引き続き、下塗り層Ａ−１及び下塗り層Ｂ−１の上表面に、８Ｗ／ｍ²・分のコロナ放電を施し、下塗り層Ａ−１の上には、下記下塗り上層塗布液ａ−２を乾燥膜厚０．１μｍになる様に下塗り上層Ａ−２として塗設し、下塗り層Ｂ−１の上には下記下塗り上層塗布液ｂ−２を塗設した。
下塗り上層塗布液ａ−２
ゼラチン ０．４ｇ／ｍ²
シリカ粒子（平均粒子径２μｍ） ０．０１ｇ／ｍ²
下塗り上層塗布液ｂ−２
スチレンブタジエン共重合ラテックス液（固形分２０％）０．０８ｇ／ｍ²
ポリエチレングリコール（質量平均分子量９００） ０．０３６ｇ／ｍ²
シリカ粒子（平均粒子径３μｍ） ０．０１ｇ／ｍ²
感光性ハロゲン化銀乳剤Ａの調製
水９００ｍｌ中にイナートゼラチン７．５ｇ及び臭化カリウム１０ｍｇを溶解して温度３５℃、ｐＨを３．０に合わせた後、硝酸銀７４ｇを含む水溶液３７０ｍｌとこれと当量の（９８／２）のモル比の臭化カリウムと沃化カリウムを含む水溶液３７０ｍｌを、ｐＡｇ７．７に保ちながらコントロールドダブルジェット法で１０分間かけて添加した。その後４−ヒドロキシ−６−メチル−１，３，３ａ，７−テトラザインデン０．３ｇを添加しＮａＯＨでｐＨを５．０に調整して平均粒子サイズ０．０６μｍ、粒子サイズの変動係数８％、〔１００〕面比率８７％の立方体沃臭化銀粒子を得た。この乳剤にゼラチン凝集剤を用いて凝集沈降させ脱塩処理後、フェノキシエタノール０．１ｇを加え、ｐＨ５．９、ｐＡｇ７．５に調整して、感光性ハロゲン化銀乳剤Ａを得た。
粉末有機銀塩Ａ（ハロゲン化銀を含む）の調製
４７２０ｍｌの純水にベヘン酸１１１．４ｇ、アラキジン酸８３．８ｇ、ステアリン酸５４．９ｇを８０℃で溶解した。次に高速で攪拌しながら１．５Ｍの水酸化ナトリウム水溶液５４０．２ｍｌを添加し十分に攪拌した。次に、濃硝酸６．９ｍｌを加えた後、５５℃に冷却して有機酸ナトリウム溶液を得た。該有機酸ナトリウム溶液の温度を５５℃に保ったまま、上記感光性ハロゲン化銀乳剤Ａ（銀０．０３８モルを含む）と純水４５０ｍｌを添加し５分間攪拌した。次に１Ｍの硝酸銀溶液７６０．６ｍｌを２分間かけて添加し、さらに２０分攪拌し、濾過により水溶性塩類を除去し乾燥した。
光熱写真画像形成材料の作製
上記で下塗りを施した支持体上に感光層側をＡ−２になるように以下の各層を順次形成して光熱写真画像形成材料試料を作製した。尚、乾燥は各々７５℃、１分間で行った。
【００６１】
感光層面側塗布
第１層：ハレーション防止層（ＡＨ）層
結合剤ＰＢＶ−１（重合度：６００） １．２ｇ／ｍ²
染料Ｃ１ ２×１０^-5モル／ｍ²
第２層：感光層
感光層の調製は以下の組成物をメチルエチルケトン溶液に添加し、塗布液を調製した。
【００６２】

【００６３】

感光層と反対側（下塗りＢ−２）にバック層およびバック層の保護層を塗布した。
【００６４】
バック層面塗布
第１層：バック層
結合剤ＰＢＶ−１（重合度：６００） １．２ｇ／ｍ²
染料Ｃ１ ７０ｍｇ／ｍ²
第２層：バック層保護膜
セルロースアセテートブチレート ０．８ｇ／ｍ²
マット剤（ＰＭＭＡ：平均粒径３μｍ） ０．０２ｇ／ｍ²
※１：帯電防止剤（本発明のπ電子導電性ポリマー）の調製は電解酸化重合法で、ステンレスプレート（３０ｃｍ×３０ｃｍ）に１．５ボルトの電位を掛けて作製した。得られたポリマーをプレートからブレードでオンライン掻き取りを行い、得られたポリマー粉末をメチルエチルケトン溶媒中にて３ｍｍのジルコニア微粒子球を用いてサンドミルにより、表１記載の分散粒子径の粒度まで粉砕、微粒子分散した。
【００６５】
尚、帯電防止剤（本発明のπ電子導電性ポリマー）の添加量は、数平均分子量を平均重合度で除した数字をモル数とした。
【００６６】
【化７】

【００６７】
写真性能の評価
露光および現像の条件は、光熱写真画像形成材料を８１０ｎｍの半導体レーザーを有するレーザー感光計で露光し、次いで熱ドラムを用いて１２０℃で８秒間熱現像処理した。その際、露光及び現像は２５℃、相対湿度５０％に調湿した部屋で行った。得られた画像の感度とカブリを自動濃度計により評価を行った。感度はカブリより０．３高い濃度を与える露光量の比の逆数として求め、試料１０１の感度を１００とする相対感度で示す。カブリの測定は、未露光の試料を熱現像し、濃度を測定した。
帯電特性の評価
湿度１８％温度２３℃に空調された実験室内でナイロン６０％およびポリエステル４０％の繊維面と試料片（５ｃｍ×５ｃｍ）を５ｋＰａの圧力を掛けながら５回摩擦し、この摩擦した試料面を直径５ｍｍ、厚さ１００μｍの円形のポリエステル（ポリエチレンテレフタレート）細片にかざしてポリエステル細片の付着程度で評価した。
【００６８】
付着個数が細片総数の３％未満をランク５、３％〜１２％未満をランク４、１２％〜２６％未満をランク３、２６％〜６０％未満をランク２、６０％以上をランク１とした。
【００６９】
耐傷性の評価
深さ３μｍの凹凸のあるローラーで５ｋＰａの加重を掛けながら試料を擦過して傷のレベルを目視評価した。
【００７０】
傷のないレベルを５、傷が最も多いレベルを１とし、中程度で、実用的に問題ないレベルを３として評価した。
【００７１】
結果を表１に示す。
【００７２】
【表１】

【００７３】
＊比較：パーフロロオクチル−Ｎ−プロピルスルホンアミドカルボン酸ナトリウム
表１から、本発明の一般式（１）で表されるπ電子導電性ポリマーおよび一般式（２）で表されるフッ素系界面活性剤を併用した本発明の試料は、（本発明の請求項１の発明の構成）、写真特性においてカブリが低く、感度が高く、帯電特性および耐傷性のよい光熱写真画像形成材料を得ることができることがわかる。。
【００７４】
また、π電子導電性ポリマーが、電解酸化重合で調製され平均粒子径０．０１μｍ〜１０μｍであること、重合度が４〜１０００であることで特に好ましいことがわかる。
【００７５】
また、一般式（２）で表されるフッ素系界面活性剤がリチウム、ナトリウムおよびカリウム等のアルカリ金属塩であることが好ましいことがわかる。
【００７６】
【発明の効果】
本発明により、写真性能において高感度、低カブリであり、かつ帯電特性および耐傷性に優れる光熱写真画像形成材料を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photothermographic image forming material, and more particularly to a photothermographic image forming material having high sensitivity and low fog in photographic performance, and excellent charging characteristics and scratch resistance.
[0002]
[Prior art]
In recent years, there has been a strong demand for photothermographic materials that do not generate waste liquids due to wet processing in terms of environmental protection and workability in the medical and printing fields. In particular, high-resolution and clear black images can be formed by thermal development. Technology for photothermographic materials that can be used for photographic technology has been commercialized and rapidly spread. Since these photothermographic materials are usually developed at a temperature of 80 ° C. to 140 ° C., they are distinguished from conventional photosensitive materials that are liquid-developed in the range of 25 ° C. to 45 ° C. and are called photothermographic image forming materials. Yes.
[0003]
Conventionally, this type of photothermographic image forming material has a problem in that it is easily charged with static electricity due to friction and peeling, and static marks and dust that become image defects are easily attached. As a solution to this problem, inorganic fine particles such as conductive tin oxide and indium oxide have been applied between the support and the photosensitive layer. However, in this method, in order to obtain conductivity, it is necessary to contain fine particles up to a density at which the fine particles come into contact with each other. If fine particles are contained up to this density, the film strength is deteriorated. Thus, attempts have been made to solve the problem by using a tough binder, a crosslinkable hardener, or the like in order to enhance the film strength, but it has been difficult to obtain satisfactory performance.
[0004]
On the other hand, the use of an organic conductive polymer has been studied, but in any case, there is no suitable solvent for dissolving the polymer, so that it is difficult to coat, and it is easy to color due to light absorption of π electrons. It was difficult to put it to practical use due to such drawbacks. As an improvement technique for this problem, European Patent Nos. 440,957 A0 and 1031875 A1 disclose the use of a water-dispersible polythiophene compound as a dopant together with a water-soluble dopant. However, when a doping agent with weak doping ability is used or when the amount of doping agent used is small, the antistatic effect is weak and insufficient, and when a doping agent with strong doping ability is used or when a large amount of doping agent is used. The antistatic effect is strengthened when it is used, but the current situation has been that the photographic performance such as fogging, sensitivity, storage stability, light resistance or color tone is impaired. In particular, the photothermographic image-forming material contains a reducing agent and an organic silver salt as essential components in addition to the photosensitive silver halide, so that it is easy to fog, it is difficult to obtain high sensitivity, and storage stability, light resistance, and silver tone are high. Since there are problems to be improved such as easy deterioration, it is very difficult to select and use a suitable antistatic agent. As for fog, examples using disulfide compounds are disclosed as described in JP-A-57-000643, JP-A-5-341432, JP-A-11-295646, and JP-A-2000-206642. Is not enough. Further, regarding sensitivity, there is a technique using a hydrazide compound, but there is a tendency that fog is increased, which is not fully satisfied. Further, regarding silver color tone, phthalazine compounds or derivatives of phthalic acid compounds have been developed, but the storage stability is liable to deteriorate.
[0005]
[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 image forming material having high sensitivity and low fog in photographic performance, and excellent in charging characteristics and scratch resistance. .
[0006]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configurations.
[0007]
1. In a photothermographic image-forming material containing photosensitive silver halide grains, an organic silver salt, a reducing agent of the organic silver salt and a binder on a support, the π electron represented by the general formula (1) in the outermost layer A photothermographic image-forming material comprising a conductive polymer and a fluorine-based surfactant represented by the general formula (2).
[0008]
2. 2. The photothermographic image-forming material as described in 1 above, wherein the π electron conductive polymer is at least one selected from a polythiophene compound, a polypyrrole compound and a polyfuran compound.
[0009]
3. 3. The photothermographic image forming material as described in 1 or 2 above, wherein the π electron conductive polymer is fine particles having an average particle diameter of 0.01 μm to 10 μm.
[0010]
4). 4. The photothermographic image-forming material as described in any one of 1 to 3 above, wherein the polymerization degree of the π-electron conductive polymer is 4 to 1000.
[0011]
5). 5. The photothermographic image forming material according to any one of 1 to 4, wherein the anionic part of the fluorosurfactant is an alkali metal salt.
[0012]
Hereinafter, the present invention will be described in detail.
The π electron conductive polymer of the present invention is a polymer compound in which π electrons contribute to conductivity, and is distinguished from an ionic conductive compound.
[0013]
The monomer compound having π electrons, which is a raw material monomer of the π electron conductive polymer of the present invention, has at least one double bond in a linear or cyclic compound. In the present invention, a double bond is used. Cyclic monomer compounds having are preferred.
[0014]
The π-electron conductive polymer of the present invention is a monomer compound having 4 to 1000 monomer units linked by radical polymerization, electrolytic oxidation polymerization, ionic polymerization or the like.
[0015]
In the case of radical polymerization, the monomer can be dissolved or dispersed in water or an organic solvent, and a normal radical initiator can be added to carry out the polymerization at 30 ° C. to 100 ° C. for 1 hour to 72 hours. .
[0016]
In the case of electrolytic oxidation polymerization, the monomer is polymerized by dissolving the monomer in water or an organic solvent, inserting a plate electrode or a rod-like electrode into this solution system, and applying a potential usually in the range of 0.1 to 100 volts. be able to. The potential is preferably a potential corresponding to the oxidation potential of the monomer, but may be lower or higher. A potential in the range of 1/2 to 2 times the oxidation potential of the monomer is particularly preferred. The electrode is preferably a plate type having a large surface area for polymerization. The material of the electrode may be a metal, but is preferably a noble metal or stainless steel that is not easily corroded. The degree of polymerization can be controlled by the initiator concentration, the monomer concentration, the type and amount of chain transfer agent used, or the polymerization temperature and time.
[0017]
Preferable examples of the π-electron conductive polymer of the present invention polymerized as described above include a π-electron conductive polymer represented by the general formula (1).
[0018]
The π electron conductive polymer represented by the general formula (1) of the present invention will be described.
In the general formula (1), R¹And R²Represents an alkyl group, alkoxy group, amino group, alkylsulfonyl group or carbamyl group, each of which may have 1 to 25 carbon atoms, X represents a sulfur atom, a nitrogen atom or an oxygen atom, and n represents 4 to 1000. Represents an integer.
[0019]
R¹And R²Examples of the alkyl group, alkoxy group, amino group, alkylsulfonyl group or carbamyl group which may be substituted include, for example, methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, dodecyl Examples of the substituent for the alkyl group include a halogen atom such as a chlorine atom or a fluorine atom, a hydroxy group, an alkoxy group (methoxy group, ethoxy group, etc.), and the like. R¹And R²May be combined. In that case, for example, an ethylene group, a butylene group, an ethyleneoxyethylene group, or the like may be formed.
[0020]
Examples of the amino group include a methylamino group, an ethylamino group, a butylamino group, and a dimethylamino group. Examples of the carbamyl group include a methylcarbamyl group, an ethylcarbamyl group, and a butylcarbamyl group. Examples of the alkylsulfonyl group include a methylsulfonyl group, an ethylsulfonyl group, and a butylsulfonyl group. X represents a sulfur atom, an oxygen atom or a nitrogen atom, and among them, a sulfur atom is preferable.
[0021]
n represents an integer of 4 to 1000, but if it exceeds 1000, the solubility becomes difficult and the coloring becomes large, so 1000 or less is preferable, and the range of 4 to 600 is particularly preferable. If it is less than 4, the conductivity may deteriorate and the scratch resistance may deteriorate.
[0022]
As a doping agent such as a polythiophene compound which is a preferable π electron conductive polymer of the present invention, an inorganic or organic anionic compound is preferable. In particular, an additive having an anionic group used as a coating aid may be added as a doping agent without being added as a doping agent. The addition amount of the polythiophene compound is preferably in the range of 1 microgram to 10 grams per unit area of the photothermographic image forming material.
[0023]
Specific examples of the π electron conductive polymer represented by the general formula (1) of the present invention will be given below, but the present invention is not limited to these compounds.
[0024]
[Chemical 3]

[0025]
[Formula 4]

[0026]
As a method for adding the π-electron conductive polymer represented by the general formula (1) of the present invention, a method in which fine particles are dispersed and added is preferable.
[0027]
As a method of dispersing fine particles, a sand mill dispersion method using glass beads or zirconia fine particle media, a method of spraying a solution from a thin tube at high speed and crushing it into a hard plate, or a method of dispersing by colliding liquid in a thin tube from two directions Etc. The fine particle dispersion diameter is preferably an average particle diameter of 0.01 μm to 10 μm in an aqueous solution, and preferably has a narrow particle size distribution. If the average particle size is less than 0.01 μm, productivity may be deteriorated, for example, it takes time to make fine particles. On the other hand, when the particle size exceeds 10 μm, the particle size distribution of the fine particles may spread and aggregation may occur.
[0028]
Other addition methods include water, alcohols (eg, methanol, ethanol, isobutyl alcohol, etc.), ketones (eg, acetone, methyl ethyl ketone, isobutyl ketone, etc.), aromatic organic solvents (eg, toluene, xylene, etc.) It can be dissolved and added.
[0029]
Next, the fluorine-type surfactant represented by General formula (2) of this invention is demonstrated.
[0030]
In the general formula (2), Rf represents a substituent containing a fluorine atom. Examples of the substituent containing the fluorine atom include an alkyl group having 1 to 25 carbon atoms (for example, a methyl group, an ethyl group, Butyl group, octyl group, dodecyl group, octadecyl group, etc.) or alkenyl group (for example, propenyl group, butenyl group, nonenyl group, dodecenyl group, etc.).
[0031]
L₁Represents a divalent linking group having no fluorine atom. Examples of the divalent linking group having no fluorine atom include alkylene groups (eg, methylene group, ethylene group, butylene group), alkyleneoxy Group (methyleneoxy group, ethyleneoxy group, butyleneoxy group, etc.), oxyalkylene group (for example, oxymethylene group, oxyethylene group, oxybutylene group, etc.), oxyalkyleneoxy group (for example, oxymethyleneoxy group, oxyethylene) Oxy group, oxyethyleneoxyethyleneoxy group, etc.), phenylene group, oxyphenylene group, phenyloxy group, oxyphenyloxy group, or a combination of these groups.
[0032]
A represents an anionic group or a base thereof, for example, a carboxylic acid group or a base thereof (sodium salt, potassium salt and lithium salt), a sulfonic acid group or a base thereof (sodium salt, potassium salt and lithium salt) and a phosphoric acid group or Examples thereof include sodium base and potassium salt.
[0033]
Y represents a trivalent or tetravalent linking group having no fluorine atom. For example, an atom composed of a trivalent or tetravalent linking group having no fluorine atom and centering on a carbon atom or a nitrogen atom. Groups. p represents an integer of 1 to 3, and q represents an integer of 2 to 3.
[0034]
The fluorine-based surfactant represented by the general formula (2) is an alkyl compound having 1 to 25 carbon atoms into which fluorine atoms are introduced (for example, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorooctyl). Group and a compound having a perfluorooctadecyl group) and an alkenyl compound (for example, a perfluorohexenyl group and a perfluorononenyl group), a trivalent to hexavalent alkanol compound in which no fluorine atom is introduced, and a hydroxyl group, respectively. An anionic group (A) is further introduced into the compound (partially Rf-modified alkanol compound) obtained by addition reaction or condensation reaction with 3 to 4 aromatic compounds or hetero compounds by, for example, sulfate esterification. Can be obtained.
[0035]
Examples of the trivalent to hexavalent alkanol compound include glycerin, pentaerythritol, 2-methyl-2-hydroxymethyl 1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentene, and 1,2,6-hexane. Examples include triol, 1,1,1-tris (hydroxymethyl) propane, 2,2-bis (butanol) -3, aliphatic triol, tetramethylolmethane, D-sorbitol, xylitol, D-mannitol and the like.
[0036]
Examples of the aromatic compound and hetero compound having 3 to 4 hydroxyl groups include 1,3,5-trihydroxybenzene and 2,4,6-trihydroxypyridine.
[0037]
Below, the preferable specific compound of the fluorine-type surfactant represented by General formula (2) is shown.
[0038]
[Chemical formula 5]

[0039]
[Chemical 6]

[0040]
As a method for adding the fluorosurfactant represented by the general formula (2) of the present invention to the coating solution, it can be added according to a known addition method. That is, it can be dissolved and added in alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, polar solvents such as dimethyl sulfoxide and dimethylformamide. Further, fine particles of 1 μm or less can be dispersed in water or an organic solvent by sand mill dispersion, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion, and added. Many techniques for fine particle dispersion are disclosed, but they can be dispersed according to these techniques. The fluorosurfactant represented by the general formula (2) is preferably added to the outermost protective layer.
[0041]
The addition amount of the fluorosurfactant represented by the general formula (2) of the present invention is 1 m.²1 × 10 per^-8~ 1x10^-1Moles are preferred, 1 × 10^-Five~ 1x10^-2Mole is particularly preferred. If it is less than the former range, charging characteristics cannot be obtained, and if it exceeds the former range, the humidity dependence is large and the storage stability under high humidity deteriorates.
(Binder)
Examples of the binder include polyvinyl alcohol derivatives (including polyacetal), methacrylate polymer derivatives, acrylate polymer derivatives, polyimide derivatives, polyamide derivatives, phenol resin derivatives, urethane resin derivatives, and polyester derivatives. Particularly preferred derivatives are polyvinyl alcohol derivatives or vinyl acetate derivatives.
(Crosslinking agent used for binder)
By forming the binder alone, it is possible to maintain adhesion to the lower layer and the upper layer and to obtain a film strength that is difficult to be damaged, but by using a crosslinking agent, it is possible to further enhance the film adhesion. . However, when the crosslinking reaction is slow, the photographic performance is not stable and the storage stability is deteriorated. The fast-acting and preferred crosslinking agent used in the present invention is a polyfunctional crosslinking agent having at least two of an isocyanate group, an epoxy group, or a vinylsulfonyl group, or an alkoxy having at least one alkoxysilane group. Mention may be made of silane compounds.
[0042]
Specific examples of preferred crosslinking agents used in the present invention are shown below.
(H1) Hexamethylene diisocyanate
(H2) Hexamethylene diisocyanate trimer
(H3) Tolylene diisocyanate
(H4) Phenylene diisocyanate
(H5) Xylylene diisocyanate
The crosslinking agent may be added after being dissolved in water, alcohols, ketones or nonpolar organic solvents, or may be added as a solid in the coating solution. The amount added is preferably equivalent to the cross-linking group of the binder, but it may be increased up to 10 times or decreased to 1/10 or less. If it is less than the above, the crosslinking reaction will not proceed, and if it is more than the above, the unreacted crosslinking agent will deteriorate the photographic properties, which is not preferable.
(Silver halide grains)
The photosensitive silver halide used in the photothermographic image-forming material of the present invention can be prepared by a method known in the field of photographic technology such as a single jet or double jet method, for example, an ammonia method emulsion, a neutral method, an acidic method. It can be prepared by any method such as a method.
[0043]
The silver halide preferably has a small grain size in order to keep the white turbidity (haze) after image formation low and to obtain good image quality. The average particle size is usually 100 nm or less, preferably 10 nm to 60 nm, particularly 20 nm to 50 nm. Further, the shape of the silver halide is not particularly limited, and examples thereof include cubic and octahedral so-called loose normal crystals, non-normal crystals such as spheres, rods, and plates. The silver halide composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.
[0044]
The amount of silver halide is usually 50% or less, preferably 25% to 0.1%, more preferably 15% to 0.1% with respect to the total amount of silver halide and the organic silver salt described below. .
[0045]
The photosensitive silver halide used in the photothermographic image-forming material of the present invention can also be used in the preparation of an organic silver salt such as halide ions as described in British Patent 1,447,454. These halogen components can coexist with the organic silver salt-forming component and silver ions are implanted therein, whereby the organic silver salt can be formed almost simultaneously.
[0046]
As another method, a silver halide forming component is allowed to act on a solution or dispersion of an organic silver salt prepared in advance, or a sheet material containing the organic silver salt, so that a part of the organic silver salt is photosensitive halogenated. It can also be converted to silver. The silver halide thus formed is in effective contact with the organic silver salt and exhibits a preferable action.
[0047]
These photosensitive silver halides include illuminance failure, metals belonging to Groups 6 to 11 of the Periodic Table of Elements, for example, ions such as Rh, Ru, Re, Ir, Os, and Fe for gradation adjustment, The complex or complex ion can be doped (contained). Although these metal ions may introduce a metal salt into silver halide as it is, they can be introduced into silver halide in the form of a metal complex or complex ion. As these transition metal complexes and metal complex ions, hexacoordinate complex ions are preferable.
[0048]
Specific examples of the ligand include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aco ligands, nitrosyl, Examples thereof include thionitrosyl and the like, preferably aco, nitrosyl and thionitrosyl. When an acoligand is present, it preferably occupies one or two of the ligands.
[0049]
Specific examples of particularly preferable doped metal atoms are rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir), and osmium (Os). One kind of these metal complexes or complex ions may be used, or two or more kinds of the same and different metals may be used in combination.
[0050]
The content of these metal ions, metal complexes and complex ions is usually 1 × 10 5 per mole of silver halide.^-9~ 1x10^-2Molar is suitable, preferably 1 × 10^-8~ 1x10^-FourIs a mole. An excessive addition amount is not preferable because it causes a decrease in sensitivity, softening, and a decrease in the maximum concentration. The compounds providing these metal ions or complex ions are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening , May be added at any stage before or after chemical sensitization, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Preferably, it is added at the stage of nucleation. In addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains. JP-A-63-29603, JP-A-2-306236, 3 As described in JP-A Nos. 167545, 4-76534, 6-110146, 5-273683, etc., the particles can be contained with a distribution.
[0051]
These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method of adding an aqueous solution of a compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or a silver salt solution and a halide solution Are added as a third aqueous solution when they are simultaneously mixed, a method of preparing silver halide grains by a method of three-liquid simultaneous mixing, a method of charging a required amount of an aqueous solution of a metal compound into a reaction vessel during grain formation, or It may be added by a method of adding and dissolving another silver halide grain previously doped with metal ions or complex ions at the time of silver halide preparation. That.
[0052]
The photosensitive silver halide prepared by the various methods described above can be chemically sensitized with, for example, a sulfur-containing compound, a gold compound, a platinum compound, a palladium compound, or a combination thereof. Regarding the method and procedure of chemical sensitization, for example, U.S. Pat. No. 4,036,650, British Patent 1,518,850, JP-A-51-22430, 51-78319, 51-81124. It is described in.
[0053]
In the present invention, it is preferable to contain a matting agent on the photosensitive layer side, and it is preferable to dispose the matting agent on the surface of the photosensitive material in order to prevent damage to the image after heat development. The matting agent is preferably contained in a mass ratio of 0.5 to 30% with respect to the total binder on the photosensitive layer side.
[0054]
Further, when a non-photosensitive layer is provided on the opposite side of the photosensitive layer with the support interposed between them, it is preferable to contain a matting agent in at least one layer on the non-photosensitive layer side, in order to prevent slipping of the photosensitive material and fingerprint adhesion In addition, it is preferable to dispose a matting agent on the surface of the photosensitive material. It is preferable to contain the matting agent in a mass ratio of 0.5 to 40% with respect to the total binder in the layer opposite to the photosensitive layer.
[0055]
The material of the matting agent used in the present invention may be either organic or inorganic. For example, as an inorganic substance, silica described in Swiss Patent No. 330,158 or the like, as an organic substance, starch described in US Pat. No. 2,322,037 or the like, Belgian Patent No. 625,451 or British Patent No. 981 198, etc., polyvinyl alcohol described in JP-B 44-3643, etc., polystyrene or polymethacrylate described in Swiss Patent No. 330,158, etc., US Pat. No. 3,079,257 Or an organic matting agent such as polycarbonate described in U.S. Pat. No. 3,022,169.
[0056]
The shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is preferably used. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle size of the matting agent indicates the diameter converted into a spherical shape.
[0057]
The matting agent used in the present invention preferably has an average particle size of 0.5 μm to 10 μm, more preferably 1.0 μm to 8.0 μm. The coefficient of variation of the particle size distribution ((standard deviation of particle size) / (average value of particle size) × 100) is preferably 50% or less, more preferably 40% or less. Preferably it is 30% or less.
[0058]
The method for adding the matting agent used in the present invention may be a method in which the matting agent is dispersed and applied in advance in the coating solution, or a method in which the matting agent is sprayed after the coating solution is applied and before drying is completed. It may be used. When a plurality of types of matting agents are added, both methods may be used in combination. The addition amount of the matting agent can be appropriately determined at a level that does not cause a haze problem depending on the size of the matting particles, but 0.01 mg / m²~ 1g / m²Is preferred. Excessive addition causes a problem with haze.
(Support)
As the support, a support such as polyethylene terephthalate, polyethylene naphthalate or syndiotactic polystyrene is preferable, and the thickness is 50 μm to 400 μm which is biaxially stretched and heat-fixed optically isotropic and has good dimensional stability. Good thing.
(Image exposure)
As the exposure method, laser exposure can be performed by the methods described in JP-A-9-304869, JP-A-9-311403 and JP-A-2000-10230. In the exposure of the photothermographic image forming material of the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photosensitive material. For example, if the photosensitive material is sensitive to infrared light, it can be applied to any light source as long as it is in the infrared light range, but the laser power is high, the photosensitive material can be made transparent, etc. From this point, an infrared semiconductor laser (780 nm, 820 nm) is more preferably used.
(Heat development device)
As an apparatus for developing the photothermographic image forming material, apparatuses described in JP-A Nos. 11-65067, 11-72897 and 11-84619 can be used.
[0059]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this.
[0060]
Example 1
Preparation of undercoated photographic support
Corona discharge treatment (8 W / m on both sides of a commercially available biaxially stretched heat-fixed polyethylene terephthalate film with an optical density of 0.170 blue-colored)²・ Apply the following undercoat coating solution a-1 on one side and dry it to make undercoat A-1, and apply the following undercoat coating solution b-1 on the opposite side and dry it. It was set as the back layer side undercoat layer B-1.
Undercoat coating liquid a-1
Butyl acrylate (30% by mass)
t-Butyl acrylate (20% by mass)
Styrene (25% by mass)
2-Hydroxyethyl acrylate (25% by mass)
Copolymer latex liquid (solid content 30%) 0.08 g / m²
Hexamethylene-1,6-bis (ethylene urea) 0.008 g / m²
Undercoat coating liquid b-1
Butyl acrylate (40% by mass)
Styrene (20% by mass)
Glycidyl acrylate (40% by mass)
Copolymer latex liquid (solid content 30%) 0.08 g / m²
Hexamethylene-1,6-bis (ethylene urea) 0.008 g / m²
Subsequently, 8 W / m on the upper surface of the undercoat layer A-1 and the undercoat layer B-1.²・ Corona discharge was applied, and on the undercoat layer A-1, the following undercoat upper layer coating solution a-2 was applied as an undercoat upper layer A-2 so as to have a dry film thickness of 0.1 μm. The following undercoat upper layer coating solution b-2 was coated on -1.
Undercoat upper layer coating solution a-2
Gelatin 0.4g / m²
Silica particles (average particle size 2 μm) 0.01 g / m²
Undercoat upper layer coating solution b-2
Styrene butadiene copolymer latex liquid (solid content 20%) 0.08 g / m²
Polyethylene glycol (mass average molecular weight 900) 0.036 g / m²
Silica particles (average particle size 3 μm) 0.01 g / m²
Preparation of photosensitive silver halide emulsion A
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 900 ml of water and adjusting the temperature to a temperature of 35 ° C. and a pH of 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and an equivalent (98/2) mole 370 ml of an aqueous solution containing potassium bromide and potassium iodide in a ratio was added over 10 minutes by the controlled double jet method while maintaining pAg 7.7. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added and the pH was adjusted to 5.0 with NaOH to obtain an average particle size of 0.06 μm and a coefficient of variation of particle size of 8 %, [100] face ratio 87% cubic silver iodobromide grains were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant and desalted, and 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5 to obtain photosensitive silver halide emulsion A.
Preparation of powdered organic silver salt A (including silver halide)
In 4720 ml of pure water, 111.4 g of behenic acid, 83.8 g of arachidic acid, and 54.9 g of stearic acid were dissolved at 80 ° C. Next, 540.2 ml of a 1.5 M aqueous sodium hydroxide solution was added while stirring at a high speed, followed by thorough stirring. Next, after adding 6.9 ml of concentrated nitric acid, the mixture was cooled to 55 ° C. to obtain an organic acid sodium solution. While maintaining the temperature of the organic acid sodium solution at 55 ° C., the above photosensitive silver halide emulsion A (containing 0.038 mol of silver) and 450 ml of pure water were added and stirred for 5 minutes. Next, 760.6 ml of 1M silver nitrate solution was added over 2 minutes, and the mixture was further stirred for 20 minutes. Water-soluble salts were removed by filtration and dried.
Production of photothermographic imaging materials
A photothermographic image-forming material sample was prepared by sequentially forming the following layers on the support that had been primed as described above so that the photosensitive layer side would be A-2. In addition, each drying was performed at 75 ° C. for 1 minute.
[0061]
Photosensitive layer side coating
First layer: Antihalation layer (AH) layer
Binder PBV-1 (degree of polymerization: 600) 1.2 g / m²
Dye C1 2 × 10^-FiveMol / m²
Second layer: photosensitive layer
The photosensitive layer was prepared by adding the following composition to a methyl ethyl ketone solution to prepare a coating solution.
[0062]

[0063]

A back layer and a protective layer for the back layer were applied to the side opposite to the photosensitive layer (undercoat B-2).
[0064]
Back layer surface coating
First layer: Back layer
Binder PBV-1 (degree of polymerization: 600) 1.2 g / m²
Dye C1 70 mg / m²
Second layer: Back layer protective film
Cellulose acetate butyrate 0.8g / m²
Matting agent (PMMA: average particle size 3 μm) 0.02 g / m²
* 1: The antistatic agent (the π-electron conductive polymer of the present invention) was prepared by electrolytic oxidation polymerization and applying a potential of 1.5 volts to a stainless plate (30 cm × 30 cm). The obtained polymer is scraped online from the plate with a blade, and the obtained polymer powder is pulverized to a particle size of the dispersed particle size shown in Table 1 by a sand mill using a 3 mm zirconia fine particle sphere in a methyl ethyl ketone solvent. Distributed.
[0065]
The addition amount of the antistatic agent (the π electron conductive polymer of the present invention) was a number obtained by dividing the number average molecular weight by the average degree of polymerization.
[0066]
[Chemical 7]

[0067]
Evaluation of photographic performance
The exposure and development conditions were such that the photothermographic image-forming material was exposed with a laser sensitometer having a 810 nm semiconductor laser, and then thermally developed at 120 ° C. for 8 seconds using a thermal drum. At that time, exposure and development were performed in a room conditioned at 25 ° C. and a relative humidity of 50%. The sensitivity and fog of the obtained image were evaluated with an automatic densitometer. Sensitivity is obtained as the reciprocal of the ratio of the exposure amount giving a density 0.3 higher than fog, and is expressed as a relative sensitivity where the sensitivity of the sample 101 is 100. The fog was measured by thermally developing an unexposed sample and measuring the density.
Evaluation of charging characteristics
In a laboratory air-conditioned at a humidity of 18% and a temperature of 23 ° C., the fiber surface of 60% nylon and 40% polyester and a sample piece (5 cm × 5 cm) were rubbed 5 times while applying a pressure of 5 kPa. It was evaluated by the degree of adhesion of the polyester strip over a 5 mm, 100 μm thick circular polyester (polyethylene terephthalate) strip.
[0068]
Less than 3% of the total number of strips is rank 5, rank 3% to less than 12% rank 4, rank 12% to less than 26% rank 3, rank 26% to less than 60% rank 2, rank 60% or more rank 1 It was.
[0069]
Evaluation of scratch resistance
The sample was abraded while applying a load of 5 kPa with a 3 μm deep uneven roller, and the level of scratches was visually evaluated.
[0070]
The level was 5 with no scratches, 1 with the most scratches, and 3 with moderate and practically no problem.
[0071]
The results are shown in Table 1.
[0072]
[Table 1]

[0073]
* Comparison: Sodium perfluorooctyl-N-propylsulfonamide carboxylate
From Table 1, the sample of the present invention in which the π-electron conductive polymer represented by the general formula (1) of the present invention and the fluorine-based surfactant represented by the general formula (2) are used together is It can be seen that a photothermographic image forming material having low fog, high sensitivity, good charging characteristics and good scratch resistance in photographic characteristics can be obtained. .
[0074]
It can also be seen that the π-electron conductive polymer is particularly preferable when it is prepared by electrolytic oxidation polymerization and has an average particle size of 0.01 μm to 10 μm and a polymerization degree of 4 to 1000.
[0075]
Moreover, it turns out that it is preferable that the fluorine-type surfactant represented by General formula (2) is alkali metal salts, such as lithium, sodium, and potassium.
[0076]
【The invention's effect】
According to the present invention, a photothermographic image forming material having high sensitivity and low fog in photographic performance and excellent in charging characteristics and scratch resistance can be provided.

Claims (5)

In a photothermographic image-forming material containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder of the organic silver salt on a support, π electrons represented by the following general formula (1) in the outermost layer A photothermographic image-forming material comprising a conductive polymer and a fluorosurfactant represented by the following general formula (2).

(In the formula, R ¹ and R ² each represents an alkyl group, an alkoxy group, an amino group, an alkylsulfonyl group, or a carbamyl group, each of which may have 1 to 25 carbon atoms, and X represents a sulfur atom, a nitrogen atom, or an oxygen atom. Represents an atom, and n represents an integer of 4 to 1000.)

(In the formula, Rf represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group containing no fluorine atom, and Y represents a trivalent or tetravalent linking group containing no fluorine atom. A represents an anionic group or a base thereof, p represents an integer of 1 to 3, and q represents an integer of 2 or 3.) 2. The photothermographic image-forming material according to claim 1, wherein the π electron conductive polymer is at least one selected from a polythiophene compound, a polypyrrole compound, and a polyfuran compound. 3. The photothermographic image forming material according to claim 1, wherein the π electron conductive polymer is fine particles having an average particle diameter of 0.01 μm to 10 μm. The photothermographic image-forming material according to any one of claims 1 to 3, wherein the polymerization degree of the π-electron conductive polymer is 4 to 1000. The photothermographic image-forming material according to any one of claims 1 to 4, wherein the anionic part of the fluorosurfactant is an alkali metal salt.