JP2004002874A - Titanyloxyphthalocyanine crystal, its preparation method and electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide new titanyloxyphthalocyanine crystals and these preparation method and to provide an electrophotographic photoreceptor which is highly sensitive to light in the region of near infrared and gives a highly qualified image by using the crystals. <P>SOLUTION: The new titanyloxyphthalocyanine crystal having a X-ray spectrum shown in Figure 1 is obtained by that, after amorphous titanyloxyphthalocyanine is dispersed and pulverized into an aqueous solution of an ionic material by using mechanical force, a water insoluble organic solvent is added thereto, the titanyloxyphthalocyanine dispersed in an aqueous phase is moved to the phase of the water insoluble organic solvent under removing water by using mechanical force, and this new titanyloxyphthalocyanine crystalis obtained by removing the water insoluble organic solvent, obtaining also the new titanyloxyphthalocyanine having a specific crystal lattice constant. The photoreceptor is produced by using these crystals as electric charge generators. <P>COPYRIGHT: (C)2004,JPO

Description

［式（Ｉ）中、Ｘ^１，Ｘ^２，Ｘ^３およびＸ^４はそれぞれＣｌまたはＢｒのいずれかを示し、ｎ，ｍ，ｌおよびｋはそれぞれ０ないし４のいずれかの整数を示す。］
図１は、このようなチタニルオキシフタロシアニン結晶のＸ線回折スペクトルの一例を示す線図である。
また、上記一般式（Ｉ）で表され、結晶格子定数（誤差範囲±１％）が、ａ＝１６．３０５８Å，ｂ＝２３．０７８Å，ｃ＝８．７１５５Å，α＝１０１．３５２°，β＝２３．０７８°，γ＝１１７．５３０°であるチタニルオキシフタロシアニン結晶によって解決される。
【００１８】
上述のようなチタニルオキシフタロシアニン結晶は、図５に示すような光吸収スペクトルを有する。図５には、比較のためにα型チタニルオキシフタロシアニンおよびＩ型チタニルオキシフタロシアニンの光吸収スペクトルも示してあるが、この発明のものはＩ型に比して紫外線波長領域から近赤外線波長領域まで光吸収能が非常に優れており、また、α型と比較しても優れており、波長８２０ｎｍ以上の領域にまで強い吸収能を有する。従って、この発明のチタニルオキシフタロシアニン結晶を電荷発生材として用いることにより、半導体レーザー光のような近赤外域の波長光に最適な感光体を得ることができる。
【００１９】
また、この発明のチタニルオキシフタロシアニン結晶は電荷発生層用塗布液中で非常に安定であり、凝集，沈殿，結晶成長が起きにくく、分散安定性に優れている。従って、電荷発生層の塗布に際して、凝集した粗大電荷発生材の存在や電荷発生材の分散の不均一に起因する微視的な層の不均一は発生せず、また、塗布液が経時的に安定しているので安定した品質の層を得るために経時的に塗布条件を変えることも必要でなくなり、感光体の製造が容易となる。また、得られる感光体の画像においても、画像ノイズや画像ムラの発生はなくなる。
また、上記の第二の課題は、非晶質チタニルオキシフタロシアニンをイオン性物質を溶解した水溶液に５０℃以下で機械的力の存在下で分散，微粒子化した後、この系に非水溶性有機溶媒を加え、機械的力の存在下、水系に分散したチタニルオキシフタロシアニンを水分を除去しながら非水溶性有機溶媒系に移行させた後非水溶性有機溶媒を除去する製法を採ることにより解決される。前記イオン性物質を溶解した水溶液の温度は３０℃以下とすることがより好ましく、また、機械的力としては歪力，剪断力，衝撃力などの挙げられる。
【００２０】
この発明の上記のチタニルオキシフタロシアニン結晶は、Ｘ線回折スペクトルにおける最大回折ピークの現れるブラッグ角による分類によれば、特開平５−３２０１６７号公報に開示されたもの（前述の第四分類）に似ているものの、明瞭な回折ピークが現れるブラッグ角７．２２°，１１．４°，１３．４°，１４．８８°および１８．８°が特開平５−３２０１６７号公報記載の許容誤差（２θ±０．２°）を考慮にいれても一致しないことから全く別物であり、新規な結晶であるといえる。さらに、Ｘ線構造解析の結果、その結晶格子定数がａ＝１６．３０５８Å，ｂ＝２３．０７８Å，ｃ＝８．７１５５Å，α＝１０１．３５２°，β＝２３．０７８°，γ＝１１７．５３０°である三斜晶系の結晶形であることが判ったが、このような結晶格子定数は従来知られているチタニルオキシフタロシアニンの結晶形の結晶格子定数とは全く異なるものであり、新規な結晶であるといえる。
【００２１】
また、第三の課題は、上記記載のＸ線回折スペクトルを有する結晶形のチタニルオキシフタロシアニンを電荷発生材として含む電子写真感光体とすることにより解決される。また、上記記載の結晶格子定数を有する結晶形のチタニルオキシフタロシアニンを電荷発生材として含む電子写真感光体とすることにより解決される。
また、第四の課題は、電荷輸送層に電荷輸送材としてヒドラゾン系化合物を用いることによって解決される。ヒドラゾン系化合物としては、下記一般式（ＩＩ）に示される化合物が好適である。
【００２２】
【化５】

［式（ＩＩ）中、Ｒ^１，Ｒ^２，Ｒ^３およびＲ^４はそれぞれ置換されてもよいアルキル基，アラルキル基，アリール基のいずれかを示し、Ｒ^５は水素原子，ハロゲン原子，アルキル基，アルコキシ基のいずれかを示す。また、Ｒ^１とＲ^２が結合して環を形成してもよく、Ｒ^１とＲ^２のどちらか一方とＲ^５が結合して環を形成してもよい。］
また、第四の課題は、電荷輸送層に電荷輸送材としてジスチリル系化合物を用いることによっても解決される。ジスチリル系化合物としては、下記一般式（ＩＩＩ）で表される化合物が好適である。
【００２３】
【化６】

［式（ＩＩＩ）中、Ｒ^１，Ｒ^２，Ｒ^３およびＲ^４はそれぞれ置換されてもよいアリール基またはアルキル基のいずれかを示し、Ｒ^５およびＲ^６はそれぞれ水素原子，アルキル基，アルコキシ基のいずれかを示し、Ａｒは置換されてもよいアリール基または芳香族複素環基のいずれかを示す。］
電荷発生層の電荷発生材として上述のようなチタニルフタロシアニン結晶を用い、電荷輸送層の電荷輸送材として上述のようなヒドラゾン系化合物またはジスチリル系化合物を用いることにより、電気特性に優れ、より高感度で、繰り返し使用においても安定した電気特性，画像品質を維持できる感光体を得ることができる。
【００２４】
また、第五の課題は、導電性基体上に下引き層が設けられ、その上にこの発明に係わる電荷発生層と電荷輸送層を積層した感光層を備えてなる電子写真感光体において、下引き層がメラミン樹脂と芳香族カルボン酸および／または芳香族カルボン酸無水物のいずれかとこれらに固定されたヨウ素を主要成分として含む硬化膜である感光体とすることによって解決される。または、下引き層がメラミン樹脂と芳香族カルボン酸および／または芳香族カルボン酸塩のいずれかとこれらに固定されたヨウ素を主要成分として含む硬化膜である感光体とすることによって解決される。
【００２５】
このようにヨウ素を加えて固定した硬化膜を下引き層とすることで、単にメラミン樹脂を芳香族カルボン酸および／または芳香族カルボン酸無水物のうちのいずれか，あるいは，芳香族カルボン酸および／または芳香族カルボン酸塩のうちのいずれかで硬化させた膜を下引き層とする場合に比して、導電性基体表面を十分に被覆しその上に電荷発生層を成膜ムラなく密着性良く良好に塗布形成することができるように、極めて厚く，例えば，１０μｍ〜２０μｍの膜厚に形成しても、残留電位が低く、繰り返し使用時においても帯電位の低下や残留電位の上昇などの不具合が発生せず、さらに、大幅な環境変化においても電気特性，画像特性の変動が少ない優れた感光体を得ることができる。その理由は現在まだ明らかではないが、例えば、ナイロン６に８０％〜１００％もの多量のヨウ素を加えた付加体が極めて電気抵抗が小さいことは知られており（Ｊ．ｏｆ　Ｍａｔ．Ｓｃｉ．，２１（１９８６）ｐ６０４〜６１０）、これらの系以外にも、ポリビニルアルコール，ポリテトラヒドロフラン，リアクリロニトリルが同様にヨウ素と付加体を作り、導電性が得られることが知られている。しかし、上述のように、メラミン樹脂に芳香族カルボン酸および／または芳香族カルボン酸無水物のうちのいずれか，あるいは，芳香族カルボン酸および／または芳香族カルボン酸塩のうちのいずれかを配合し、これにヨウ素を加えて固定した硬化膜は、ヨウ素を少量加えるだけで良好な導電性が得られ、しかも環境が大幅に変化しても変動が少ないことは知られていなかった。本発明者らはこの点に着目して、このような硬化膜を下引き層とし、上述の新規なチタニルオキシフタロシアニンを電荷発生材として組み合わせることにより、下引き層として極めて有効に機能することを見出したのである。
【００２６】
【発明の実施の形態】
この発明のチタニルオキシフタロシアニン結晶の製法を例示的に説明する。
まず、例えばｏ−フタロジニトリルやアミノイミノイソインドレニンもしくはアルコキシイミノイソインドレニンとチタン化合物をα−クロロナフタレンなどの不活性高沸点溶媒中で反応させる。反応温度は１６０℃〜３００℃で行われるが、通常は１６０℃〜２６０℃が好ましい。
ここで、チタン化合物としては、四塩化チタン，三塩化チタン，四臭化チタンなどのハロゲン化チタンやアルコキシチタンを用いることができるが、四塩化チタンがコストの点で好ましい。しかし、四塩化チタン（ＴｉＣｌ_４）などのハロゲン化チタンを反応試薬として用いた場合には、反応は下記の反応式に従い、第一段階で不活性高沸点溶媒中での反応でジクロロチタニウムフタロシアニン（ＰｃＴｉＣｌ_２）が生成し、第二段階でこれを加水分解することによりチタニルオキシフタロシアニン（ＰｃＴｉ＝Ｏ）が得られる。ここでＰｃはフタロシアニンを表す。
【００２７】
【化７】

以下、チタン化合物としてハロゲン化チタンを用いた場合について、製法をさらに詳細に説明する。
反応に用いられる不活性高沸点溶媒としては、ジクロロベンゼン，トリクロロベンゼン，α−クロロナフタレン，β−クロロナフタレン，ジフェニルエーテル，α−メチルナフタレン，メトキシナフタレン，ジフェニルエタン，エチレングリコールジアルキルエーテル，キノリンなどの反応に不活性な高沸点有機溶媒が挙げられる。
【００２８】
反応温度は通常１６０℃〜３００℃，好ましくは１８０℃〜２５０℃である。反応後、生成したジクロロチタニウムフタロシアニンを濾別し、反応に用いた溶媒で洗浄し、反応時に生成した不純物や未反応の原料を除く。
次に、メタノール，エタノール，イソプロピルアルコールなどのアルコール類、テトラヒドロフラン，ジオキサンなどのエーテル類、ジメチルホルムアミド，Ｎ−メチル−２−ピロリドンなどのアミド類、スルホラン、ジメチルスルホキシド、モルホリン、ピリジン、などの電子供与性の溶媒で処理することが好ましい。
【００２９】
次に、このジクロロチタニウムフタロシアニンを水溶液中で加熱処理することにより、加水分解されて、チタニルオキシフタロシアニンが得られる。このようにして得られたチタニルオキシフタロシアニンは、さらに、高純度に精製することが好ましい。精製法としては、洗浄法，再結晶法，ソックスレーなどの抽出法，および熱懸濁法などがある。また、昇華精製なども可能である。精製法は、これらに限られるものではなく、未反応物，反応副生物および不純物を除去できでればいずれでもよい。
次に、このチタニルオキシフタロシアニンを温度５℃以下で濃硫酸に分散もしくは溶解させた後、この液を室温以下の大量の水に注ぐ。析出したチタニルオキシフタロシアニンを濾別し、十分な水で中性になるまで洗浄した後、乾燥する。このようにして得られたチタニルオキシフタロシアニンのＸ線回折スペクトルは明瞭なピークを示さない結晶化度の低い非晶質に近いものである。
【００３０】
次に、このようにして得られたチタニルオキシフタロシアニンをイオン性物質を溶解した水溶液に温度５０℃以下，好ましくは３０℃以下で歪力，剪断力，衝撃力などの機械的力の存在下で分散，微粒子化する。次に、この系に非水溶性有機溶媒を加え、機械的力の存在下、水系に分散したチタニルオキシフタロシアニンを水分を除去しながら非水溶媒系に移行させる。次に、このようにして得られたチタニルオキシフタロシアニンのペーストを、用いた有機溶媒を溶かすメタノール，アセトンなどの親水性溶媒で洗浄した後、水でイオン性物質を除去した後、乾燥することによって、この発明の分散性に優れ、さらに電子写真特性に優れたチタニルオキシフタロシアニン結晶が得られる。
【００３１】
用いられるイオン性物質としては、水に溶けた場合イオンとなり水に導電性を付与するものであればよい。従って、有機化合物，無機化合物いずれでも差し支えない。無機化合物としては、食塩，ぼう硝，ケイ酸ソーダ，塩化カリウムなどが挙げられる。有機化合物としては、カルボン酸化合物や４級化されたアミン化合物などが挙げられる。しかし、経済性，精製の容易さなどの点を考慮すると、無機化合物が好ましい。
また、非水溶性有機溶媒としては、直鎖脂肪族炭化水素，分枝脂肪族炭化水素，環状炭化水素，もしくは芳香族炭化水素が選ばれる。これらの化合物は置換基を有してもよい。置換基としては、ニトロ基やハロゲン基が好ましい。
【００３２】
また、この発明における機械的力を与える装置としては、アトライター，ボールミル，ハイスピードミキサー，バンバリーミキサー，スペックミキサー，ロールミル，３本ロール，ナノマイザー，スタンプミル，遊星ミル，振動ミル，ニーダーなどが挙げられる。また、必要とあれば、分散メディアとして、ガラスビーズ，スチールビーズ，ジルコニアビーズ，アルミナボール，ジルコニアボール，フリント石などを用いてもよい。
図７は、このようにして得られたチタニルオキシフタロシアニン結晶を電荷発生材として用いる，この発明に係わる感光体の一実施例の模式的断面図で、導電性基体１上に、下引き層２を介して電荷発生層４と電荷輸送層５とが積層された感光層３が設けられた，いわゆる機能分離積層型の構成の感光体である。下引き層２は、基体からの電荷キャリアの注入の抑制，感光層の成膜ムラの防止や接着性の向上などの目的で、必要に応じて設けられるものである。
【００３３】
導電性基体は、材質的には導電性が付与された材料であればよく、素材的には種々のものが用いられる。また、形状についても板状，シート状，円筒状などいずれでもよく、特に限定されるものではない。例えば、アルミニウム，バナジウム，ニッケル，銅，亜鉛，パラジウム，インジウム，すず，白金，ステンレス鋼，クロム，真鍮などの金属ドラムや金属シート、これらの金属を蒸着またはラミネートしたプラスチックシート、導電性材料を導電性プラスチックやプラスチックに分散させた材料からなるプラスチックドラムやプラスチックシートなどが使用される。
【００３４】
下引き層としては、メラミン樹脂と芳香族カルボン酸および／または芳香族カルボン酸無水物のうちのいずれか，メラミン樹脂と芳香族カルボン酸および／または芳香族カルボン酸塩のうちのいずれかの一種類，あるいは二種類以上の混合物とこれらに固定されたヨウ素を主要成分として含む硬化膜が好適である。
この発明に係わるメラミン樹脂とは、メラミンをホルムアルデヒドと反応させてメチロール化合物とし、さらにアルコールによりブチルエーテル化したものである。また、芳香族カルボン酸，芳香族カルボン酸無水物，芳香族カルボン酸塩とは、テレフタル酸，イソフタル酸，無水フタル酸，トリメリット酸，ピロメリット酸，無水ピロメリット酸，ナフタレンカルボン酸，安息香酸，およびこれらのアンモニウム塩，硫酸塩などである。これらは、一種類，あるいは二種類以上組み合わせて混合して用いてもよい。
【００３５】
メラミン樹脂に対して加えられる芳香族カルボン酸の総量は、メラミン樹脂１００重量部に対して５重量部〜１００重量部が好ましい。添加量が５重量部未満であると膜の硬化の度合いが低下して、電荷発生層を塗布する際に膜の膨潤，溶解などの不具合が発生し、１００重量部を超えると塗布液のポットライフが短くなるので好ましくない。
また、下引き層には塗布膜のタレを防止するため、また、基体からの反射光に起因する画像上の干渉縞を防止するため、フィラーを添加してもよい。フィラーとしては酸化チタン，酸化アルミニウム，カオリン，タルク，酸化ケイ素などが用いられる。
【００３６】
下引き層は、上述のような硬化膜が非常に好適であるが、これらの硬化膜に限られるものではなく、従来から知られているアルマイトなどの金属酸化物からなる層や、ナイロン６，ナイロン６６，ナイロン１１，ナイロン６１０，共重合ナイロン，アルコキシメチル化ナイロンなどのポリアミド、カゼイン、ポリビニルアルコール、エチレン−アクリル酸共重合体、ゼラチン、ポリビニルブチラールなどの皮膜形成性高分子樹脂からなる層や、酸化亜鉛，酸化チタン，酸化アルミニウムなどの金属酸化物、窒化ケイ素、炭化ケイ素、カーボンブラックなどの導電性，半導電性もしくは誘電性の粒子を分散した樹脂からなる層でもよい。
【００３７】
電荷発生層は、電荷発生材を結着材とともに溶媒に分散，溶解させた塗液を塗布して形成される。電荷発生材は、この発明のチタニルオキシフタロシアニン結晶が好適であるが、これに限られることはなく、他の電荷発生材を併用してもよい。併用できる電荷発生材としては、各種結晶形の無金属フタロシアニン、フタロシアニン骨格の中心金属が鉄，コバルト，ニッケル，アルミニウム，ケイ素，銅，チタン，バナジウム，インジウム，ガリウム，ゲルマニウム，マグネシウムなどの各種金属フタロシアニン、ビスアゾ，トリアゾ系化合物、アントラキノン系化合物、ペリレン系化合物、ペリノン系化合物、アズレニウム塩系化合物、スクアリウム塩系化合物、ピロロピロール系化合物などが挙げられる。また、この発明において好適に用いられる結着剤は、疏水性で、かつ、高い電気絶縁性のフィルム形成性高分子重合体あるいは共重合体である。具体的には、フェノール樹脂，ポリエステル樹脂，酢酸ビニル樹脂，ポリカーボネート樹脂，ポリペプチド樹脂，セルロース系樹脂，ポリビニルピロリドン，ポリエチレンオキサイド，ポリ塩化ビニル樹脂，ポリ塩化ビニリデン樹脂，ポリスチレン樹脂，ポリビニールアセテート，スチレン−ブタジエン共重合体，塩化ビニリデン−アクリロニトリル共重合体，塩化ビニル−酢酸ビニル共重合体，塩化ビニル−酢酸ビニル−無水マレイン酸共重合体，シリコン−アルキッド樹脂，フェノール−ホルムアルデヒド樹脂，スチレン−アルキッド樹脂，ポリビニルアルコール，アクリル系共重合体樹脂，メタクリル系共重合体樹脂，シリコーン樹脂，メタアクリロニトリル系共重合体樹脂，ポリビニルブチラール，ポリ塩化ビニリデン樹脂などが挙げられる。これらは単独または２種以上混合して用いられる。電荷発生層の膜厚は０．０１μｍ〜５μｍとされる。
【００３８】
電荷輸送層は、正孔輸送能を有する物質を含んでなる層である。正孔輸送材としては、ヒドラゾン系化合物，または，ジスチリル系化合物が用いられる。ヒドラゾン系化合物としては、前記一般式（ＩＩ）で示される化合物が好適である。その代表的な具体例を下記に示す。
【００３９】
【化８】

【００４０】
【化９】

【００４１】
【化１０】

【００４２】
【化１１】

また、ジスチリル系化合物としては、前記一般式（ＩＩＩ）で示される化合物が好適である。その代表的な具体例を下記に示す。
【００４３】
【化１２】

【００４４】
【化１３】

【００４５】
【化１４】

【００４６】
【化１５】

【００４７】
【化１６】

【００４８】
【化１７】

【００４９】
【化１８】

【００５０】
【化１９】

【００５１】
【化２０】

【００５２】
【化２１】

【００５３】
【化２２】

【００５４】
【化２３】

【００５５】
【化２４】

【００５６】
【化２５】

【００５７】
【化２６】

【００５８】
【化２７】

しかしながら、使用できる正孔輸送材は上述の化合物に限られるものではなく、従来から知られている種々の物質を用いることが可能である。例えば、米国特許第４１５０９８７号明細書，米国特許第４２７８７４７号明細書，西ドイツ特許公開明細書第２９３９４８３号，英国特許公開明細書第２０３４４９３号，ヨーロッパ特許公開明細書第１３１７２号などに記載されているようなヒドラゾン系化合物、特開昭４９−１０５５３６号公報に記載されているようなピラゾリン系化合物、特開昭５４−１１２６３７号公報，米国特許第３１８９４４号明細書に記載されているようなオキサジアゾール系化合物、特開昭５０−３１７３３号公報に参照されているようなスチリル化合物、米国特許第３５６７４５０号明細書，特公昭４９−３５７０２号公報，西ドイツ国特許第１１１０５１８号明細書，米国特許第３１８０７０３号明細書，米国特許第３２４０５９７号明細書，米国特許第３６５８５２０号明細書，米国特許第４２３２１０３号明細書，米国特許第４１７５９６１号明細書，米国特許第４０１２３７６号明細書，特開昭５５−１４４２５０号公報，特開昭５６−１１９１３２号公報，特公昭３９−２７５７７号公報に記載されているようなアリールアミン化合物、米国特許第３５４２５４６号明細書に記載されているようなオキサゾール系化合物、米国特許第３１８０７２９号明細書，特開昭４９−１０５５３６号公報に記載されているようなピラゾリンやピラゾロン系化合物、米国特許第３６１５４０２号明細書，米国特許第３８２０９８９号明細書，米国特許第３５４２５４４号明細書，特公昭４５−５５５号公報，特公昭５１−１０９８３号公報に記載されているようなポリアリールアルカン系化合物、特公昭３４−１０９６６号公報に記載されているようなポリビニルカルバゾールおよびその誘導体、特開昭５０−８５３３７号公報に記載されているようなＮ−アクリルアミドメチルカルバゾールの重合体、特開昭５０−９３４３２号公報に記載されているような６−ビニルインドロ（２，３−６）キノキサリンポリマー、特公昭４３−１８６７４号公報，特公昭４３−１９１９２号公報に記載されているようなビニル重合体、特開昭５６−９０８８３号公報，特開昭５６−１６１５５０号公報に記載されているようなトリフェニルメタンポリマー、特公昭４３−１９１９３号公報に記載されているようなスチレン共重合体やポリアセナフテン，ポリインデン，アセナフチレンとスチレンの共重合体、特公昭５６−１３９４０号公報に記載されているようなホルムアルデヒド系縮合樹脂などの化合物が挙げられる。これらの正孔輸送材は、それ自体が皮膜形成性を有する場合にはその溶液を塗布して電荷輸送層を形成してもよいが、低分子化合物でそれ自体では皮膜形成性を有しない場合には成膜性のある樹脂とともに溶解した溶液を塗布して電荷輸送層を形成する。電荷輸送層の膜厚は５μｍ〜４０μｍとされる。
【００５９】
さらに、上記の感光層には、感度の向上や残留電位の減少、あるいは繰り返し使用時の特性の変動を低減する目的で、必要に応じて、電子受容性物質を含有させることができる。このような電子受容性物質としては、例えば、無水琥珀酸，無水マレイン酸，ジブロム無水琥珀酸，無水フタル酸，３−ニトロ無水フタル酸，４−ニトロ無水フタル酸，無水ピロメリット酸，ピロメリット酸，トリメリット酸，無水トリメリット酸，フタルイミド，４−ニトロフタルイミド，テトラシアノエチレン，テトラシアノキノジメタン，クロラニル，ブロマニル，ｏ−ニトロ安息香酸などの電子親和力の大きな化合物を挙げることができる。
【００６０】
また、上記の感光層には、耐環境性や有害な光に対する安定性を向上させる目的で、酸化防止剤や光安定剤などの劣化防止剤を含有させることもできる。このような目的に用いられる化合物としては、トコフェロールなどのクロマノール誘導体およびそのエーテル化化合物もしくはエステル化化合物，ポリアリールアルカン化合物，ハイドロキノン誘導体およびそのモノエーテル化化合物もしくはジエーテル化化合物，ベンゾフェノン誘導体，ベンゾトリアゾール誘導体，チオエーテル化合物，フェニレンジアミン誘導体，ホスホン酸エステル，亜リン酸エステル，フェノール化合物，ヒンダードフェノール化合物，直鎖アミン化合物，環状アミン化合物，ヒンダードアミン化合物などが挙げられる。
【００６１】
上述の各層はディップコーター，スプレーコーター，ワイヤバーコーター，アプリケーター，ドクターブレード，ローラーコーター，カーテンコーター，ビードコーターなどの通常知られている塗工装置を用いて塗布形成される。
【００６２】
【実施例】
以下、この発明の具体的な実施例について説明する。例中、部は重量部を、％は重量％をそれぞれ表す。
まず、この発明のチタニルオキシフタロシアニンの製法の実施例について説明する。
［チタニルオキシフタロシアニンの合成例１］
攪拌機と冷却器のついた容量２リットルの四つ口フラスコにフタロジニトリル１２８部を入れ、これにキノリン１０００部を加え、次に窒素雰囲気下で四塩化チタン４７．５部を滴下する。滴下後、昇温し、加熱しながら２００℃±１０℃で８時間反応させた後、放冷し、１３０℃で熱時濾過し、１３０℃に加熱したキノリン５００部で洗浄した。さらに、１３０℃に加熱したＮ−メチル−２−ピロリドンで濾液が透明になるまで十分に洗浄する。次にメタノール，水の順に洗浄し、ウェットケーキ中に溶剤が無くなるまで洗浄する。得られたウェットケーキを３％苛性ソーダ水溶液１０００部に分散し、４時間加熱後、濾液が中性になるまで濾過水洗する。次に、このケーキを３％の塩酸水溶液１０００部に分散し、４時間加熱後、濾液が中性になるまで水洗する。さらに、メタノールおよびアセトンで洗浄する。この、アルカリ─酸─メタノール─アセトンの精製の操作を、メタノール，アセトンでの濾液が完全に無色になるまで数回繰り返した後乾燥する。収量は１０１．２部であった。このようにして得られたチタニルオキシフタロシアニンのＦＤＭＳ分析の結果は、チタニルオキシフタロシアニンの分子量である５７６のところに単一のピークのみが観察され、不純物のないチタニルオキシフタロシアニンであった。このチタニルオキシフタロシアニンのＸ線回折スペクトルを図２に示す。この結晶形は特開昭６２−６７０９４号公報に記載されているＩ型であった。
【００６３】
［チタニルオキシフタロシアニンの結晶変換例１］
上述の合成例１で得られたチタニルオキシフタロシアニン５０部を−１０℃以下の濃硫酸７５０部に液温が−５℃以上にならないように冷却攪拌しながら徐々に加えた。この液をさらに２時間攪拌した後、０℃の氷水中に滴下した。析出した青色物質を濾過水性した後、このケーキを２％苛性ソーダ水溶液５００部に分散後加熱し、その後濾液が完全に中性になるまで水洗した後、乾燥した。得られたチタニルオキシフタロシアニンの収量は４７部であり、そのＸ線回折スペクトルは図３に示されるように回折強度が殆ど無い非晶質であった。
【００６４】
［チタニルオキシフタロシアニン結晶の製造実施例１］
結晶変換例１で得られた非晶質チタニルオキシフタロシアニン４０部，食塩１００部，水４００部の混合物をジルコニアビーズの充填されたサンドミル（シンマルエンタプライゼス社製；商品名「ダイノミル」）中で、室温下で、３時間分散，微粒子化した。次に、ジクロロトルエン２００部を加え、さらにサンドミルの稼働を続ける。稼働中に、チタニルオキシフタロシアニンは徐々に水系から油層系へ移行する。このようにして、分離されてくる水分を取り除きから３時間分散，微粒子化を行った。次に、内容物を取り出し、水蒸気蒸留でジクロロトルエンを留出させた後、残っているチタニルオキシフタロシアニンを水で濾過し、その後乾燥する。得られたチタニルオキシフタロシアニンは、そのＸ線回折スペクトルが図１に示されるように、ブラッグ角（２θ±０．２°）７．２２°，９．６０°，１１．６０°，１３．４０°，１４．８８°，１８．３４°，２３．６２°，２４．１４°，２７．３２°に明瞭な回折ピークを有し、かつ、９．６０°の回折ピークが最大回折ピークであり、この発明のチタニルオキシフタロシアニン結晶であった。また、このチタニルオキシフタロシアニン結晶の結晶格子定数（誤差範囲±１％）は、ａ＝１６．３０５８Å，ｂ＝２３．０７８Å，ｃ＝８．７１５５Å，α＝１０１．３５２°，β＝２３．０７８°，γ＝１１７．５３０°であった。
【００６５】
［チタニルオキシフタロシアニン結晶の製造実施例２］
結晶変換例１で得られた非晶質チタニルオキシフタロシアニン４０部，食塩１００部，水４００部の混合物を製造実施例１と同様のサンドミル中で、室温下で、３時間分散，微粒子化した。次に、内容物を２軸ニーダーに移した後、α−ジクロロナフタレン２０部を加え、ニーダーを稼働させる。稼働中にチタニルオキシフタロシアニンは徐々に水系から油層系へ移行する。このようにして、分離されてくる水分を取り除きながら３時間分散，微粒子化を行った。次に、内容物を取り出し、水蒸気蒸留でα−ジクロロナフタレンを留出させた後、残っているチタニルオキシフタロシアニンを水で濾過し、その後乾燥する。このようにして製造実施例１と同様に、図１に示すようなＸ線回折スペクトルを有する，この発明のチタニルオキシフタロシアニン結晶を得た。
【００６６】
［チタニルオキシフタロシアニン結晶の製造実施例３］
結晶変換例１で得られた非晶質チタニルオキシフタロシアニン４０部，食塩１００部，水４００部の混合物をジルコニアボールが充填されたボールミル中で、室温下で、３時間分散，微粒子化した。次に、ジクロロトルエン２００部を加え、さらにボールミルの稼働を続ける。稼働中にチタニルオキシフタロシアニンは徐々に水系から油層系へ移行する。このようにして、分離されてくる水分を取り除きながら８時間分散，微粒子化を行った。次に、内容物を取り出し、水蒸気蒸留でジクロロトルエンを留出させた後、残っているチタニルオキシフタロシアニンを水で濾過し、その後乾燥する。このようにして製造実施例１と同様に、図１に示すようなＸ線回折スペクトルを有する，この発明のチタニルオキシフタロシアニンを得た。
【００６７】
［チタニルオキシフタロシアニン結晶の製造比較例１］
特開平２−１３１２４３号公報の実施例の合成例１に従ってチタニルオキシフタロシアニンの結晶変換を行う。すなわち、チタニルオキシフタロシアニン５ｇを３℃〜５℃の温度で９０％硫酸１００ｇ中で２時間攪拌した後濾過し、得られた硫酸溶液を水３リットル中に滴下して析出した結晶を取り出した。この結晶を脱イオン水で濾液が中性になるまで洗浄を繰り返した。このようにして得られたウェットケーキに分散媒としてｏ−ジクロルベンゼンを加え、サンドグラインダーで室温でミリングを行った。続いて、分散媒を除去し、アセトン，メタノールで洗浄を行い、鮮明な青色結晶を得た。得られたチタニルオキシフタロシアニン結晶のＸ線回折スペクトルは、ブラッグ角（２θ）２７．３°に最大回折ピークを有し、６．８°には６°〜８°の範囲内では最大の回折ピークを有する，特開平２−１３１２４３号公報の明細書に記載されているのと同一の結晶形であった。
【００６８】
［チタニルオキシフタロシアニン結晶の製造比較例２］
特開昭６２−１３４６５１号公報に開示されている方法により、α型チタニルオキシフタロシアニンを作製した。すなわち、フタロジニトリル４０ｇ，四塩化チタン１８ｇおよびα−クロロナフタレン５００ｃｃの混合物を窒素雰囲気下で温度２４０℃〜２５０℃で３時間加熱攪拌して反応を完結させ、その後、濾過してジクロロチタニウムフタロシアニンを得た。得られたジクロロチタニウムフタロシアニンと濃アンモニア水３００ｃｃの混合物を１時間加熱還流した後、アセトンによりソックスレー抽出にて精製したものを乾燥して、チタニルオキシフタロシアニンを得た。このチタニルオキシフタロシアニンは、図４に示すようなＸ線回折スペクトルを有するα型結晶であることが確認された。
【００６９】
［電荷発生層用塗布液の分散安定性，電荷発生層外観，および感光体画像］
次に、上述のようにして得られた各種チタニルオキシフタロシアニンを用いて電荷発生層用塗布液を調製し、調製直後と３週間静置した後の分散状態の変化および浸漬塗工法で成膜した電荷発生層の外観を観察し、また、調製直後と３週間静置後の電荷発生層用塗布液を用いて作製した各感光体の画像を評価する。
上述の、製造実施例１，合成例１，製造比較例２，製造比較例１で得られた各チタニルオキシフタロシアニン２部をテトラヒドロフラン９７部に塩化ビニル−酢酸ビニル共重合樹脂（ユニオンカーバイド社製；商品名「ＶＭＣＨ」）を溶解した樹脂液とともにボールミルで６時間分散して、下記表１に示すような電荷発生層用塗布液Ｎｏ．１〜Ｎｏ．４を調製した。
【００７０】
【表１】

これらの電荷発生層用塗布液について、調製直後と３週間静置後との塗布液分散状態を目視で観察評価した。
次に、外径３０ｍｍのアルミニウム円筒の外周面に、共重合ポリアミド樹脂（東レ（株）製；商品名「アミランＣＭ−８０００」）１０部をエタノール１９０部とともにボールミルで３時間混合し溶解させた塗布液を、ワイヤーバーコーターで塗布し、温度１００℃で１時間乾燥して膜厚０．５μｍの下引き層を形成した。この下引き層上に、上述の各種電荷発生層用塗布液の調製直後のものと３週間静置後のものとをそれぞれ塗布し、温度１００℃で２時間乾燥して膜厚０．３μｍの電荷発生層を形成し、その外観を目視で観察評価した。続いて、電荷輸送材としての１−フェニル−１，２，３，４−テトラヒドロキノリン−６−カルボアルデヒド−１’，１’−ジフェニルヒドラゾン１０部とポリカーボネート樹脂（帝人化成（株）製；商品名「パンライトＫ−１３００」）１０部とを塩化メチレン１００部に溶かした塗液を前記各電荷発生層上に塗布，乾燥して膜厚１５μｍの電荷輸送層を形成して、Ｎｏ．１〜Ｎｏ．４の各感光体を作製した。
【００７１】
このようにして作製した各感光体について、市販の半導体レーザービームプリンターを用いて画像を評価した。
以上の観察，評価の結果を表２に示す。
【００７２】
【表２】

表２に見られるように、この発明の電荷発生層用塗布液では、３週間静置後も電荷発生材の凝集や沈降が起こらず、その結果、経時後における電荷発生層の塗工においても塗工条件を変えることなく、凝集物や塗工ムラの無い良好な電荷発生層が得られ、感光体の画像も凝集物や塗布ムラに起因する欠陥の無い優れた画質であった。また、メモリーの発生も認められなかった。
［感光体作製および特性評価］
次に、上述の各種チタニルオキシフタロシアニンを電荷発生材として用い、これと組み合わせて用いる電荷輸送材を変えて、また、下引き層を変えて、感光体を作製し特性を評価する。電気特性評価用としては平板の感光体を作製した。
【００７３】
実施例１
アルミニウム基板上に、共重合ポリアミド樹脂（東レ（株）製；商品名「アミランＣＭ−８０００」）１０部をエタノール１９０部とともにボールミルで３時間混合し溶解させた塗布液を、ワイヤーバーコーターで塗布し、温度１００℃で１時間乾燥して膜厚０．５μｍの下引き層を形成した。この下引き層上に、前述の各電荷発生層用塗布液をそれぞれ塗布し、温度１００℃で２時間乾燥して膜厚０．３μｍの電荷発生層を形成した。続いて、電荷輸送材としての１−フェニル−１，２，３，４−テトラヒドロキノリン−６−カルボアルデヒド−１’，１’−ジフェニルヒドラゾン１０部とポリカーボネート樹脂（帝人化成（株）製；商品名「パンライトＫ−１３００」）１０部とを塩化メチレン１００部に溶かした塗布液を前記各電荷発生層上に塗布，乾燥して膜厚１５μｍの電荷輸送層を形成して、実施例１−１および比較例１−１，１−２，１−３の各感光体を作製した。
【００７４】
電気特性の測定は、川口電機製作所製の静電記録紙試験装置ＳＰ−４２８を用いて行った。暗所で、コロトロン方式のコロナ放電で、実施例１−１の感光体表面を帯電位Ｖ_０が−６００Ｖになるように放電電圧を調整し、その放電電圧で各感光体表面を帯電して帯電位Ｖ_０を測定し、続いて、コロナ放電を中止し暗所で５秒間放置後、一般的なレーザープリンターに使用される半導体レーザーの発振波長が７６０ｎｍ〜８００ｎｍであることから、５００ｗのキセノンランプを光源としてモノクロメータで単色光とした波長７８０ｎｍの光を各感光体表面に照射し、表面電位が１／２にまで減少する露光エネルギーＥ_１／２（μＪ／ｃｍ^２）で感度を評価し、さらに照射５秒後の残留電位Ｖ_Ｒ５を測定する。次に、コロナ放電電圧を上記設定電圧に維持し、上記帯電─露光の操作を連続して１００００回繰り返した後、Ｖ_０，Ｅ_１／２およびＶ_Ｒ５を同様に測定して感光体の疲労特性を評価した。その結果を表３に示す。
【００７５】
【表３】

表３に見られるように、製造実施例１のチタニルオキシフタロシアニン結晶を用いた実施例１−１の感光体が最も感度が優れ、疲労特性も良好である。この発明のチタニルオキシフタロシアニン結晶の電荷発生材としての優位性は明らかである。
実施例２
実施例１と同様にして基体上に下引き層を形成した。この下引き層上に、前述の製造実施例１で得られたチタニルオキシフタロシアニン２部をテトラヒドロフラン９７部に塩化ビニル−酢酸ビニル共重合樹脂（ユニオンカーバイド社製；ＶＭＣＨ）を溶解した樹脂液とともにボールミルで６時間分散して調製した電荷発生層用塗布液を塗布し、温度１００℃で２時間乾燥して膜厚０．３μｍの電荷発生層を形成した。この電荷発生層上に、電荷輸送材としての前記のヒドラゾン系化合物（ＩＩ−５）１０部とポリカーボネート樹脂（帝人化成（株）製；商品名「パンライトＫ−１３００」）１０部とを塩化メチレン１００部に溶かした液を塗布，乾燥して膜厚１５μｍの電荷輸送層を形成して、感光体を作製した。
【００７６】
実施例３
実施例２において、電荷輸送材を前記のヒドラゾン系化合物（ＩＩ−５）からヒドラゾン系化合物（ＩＩ−９）に代えたこと以外は、実施例２と同様にして感光体を作製した。
実施例４
実施例２において、電荷輸送材を前記のヒドラゾン系化合物（ＩＩ−５）からヒドラゾン系化合物（ＩＩ−１５）に代えたこと以外は、実施例２と同様にして感光体を作製した。
【００７７】
比較例１
実施例２において、電荷発生材を前記製造実施例１で得られたチタニルオキシフタロシアニンから前記合成例１で得られたチタニルオキシフタロシアニンに代えたこと以外は、実施例２と同様にして感光体を作製した。
比較例２
実施例２において、電荷発生材を前記製造実施例１で得られたチタニルオキシフタロシアニンから前記製造比較例１で得られたチタニルオキシフタロシアニンに代えたこと以外は、実施例２と同様にして感光体を作製した。
【００７８】
比較例３
実施例２において、電荷発生材を前記製造実施例１で得られたチタニルオキシフタロシアニンから前記製造比較例２で得られたチタニルオキシフタロシアニンに代えたこと以外は、実施例２と同様にして感光体を作製した。
比較例４
実施例２において、電荷輸送材を前記のヒドラゾン系化合物（ＩＩ−５）から下記構造式（Ｈ−１）に示す化合物に代えたこと以外は、実施例２と同様にして感光体を作製した。
【００７９】
【化２８】

以上のようにして作製した実施例２〜４および比較例１〜４の各感光体の特性を実施例１に準じて評価した。その結果を表４に示す。
【００８０】
【表４】

表４に見られるように、この発明のチタニルオキシフタロシアニン結晶とヒドラゾン系化合物とを組み合わせ感光体の優位性は明らかである。
実施例５
実施例２と同様にして基体上に電荷発生層までを形成した。その電荷発生層上に、電荷輸送材としての前記のジスチリル系化合物（ＩＩＩ−２）１０部とポリカーボネート樹脂（帝人化成（株）製；商品名「パンライトＫ−１３００」）１０部とを塩化メチレン１００部に溶かした塗液を塗布，乾燥して膜厚１５μｍの電荷輸送層を形成して、感光体を作製した。
【００８１】
実施例６
実施例５において、電荷輸送材を前記のジスチリル系化合物（ＩＩＩ−２）から前記のジスチリル系化合物（ＩＩＩ−１９）に示す化合物に代えたこと以外は、実施例５と同様にして感光体を作製した。
実施例７
実施例５において、電荷輸送材を前記のジスチリル系化合物（ＩＩＩ−２）から前記のジスチリル系化合物（ＩＩＩ−５０）に示す化合物に代えたこと以外は、実施例５と同様にして感光体を作製した。
【００８２】
実施例８
実施例５において、電荷輸送材を前記のジスチリル系化合物（ＩＩＩ−２）から前記のジスチリル系化合物（ＩＩＩ−７４）に示す化合物に代えたこと以外は、実施例５と同様にして感光体を作製した。
実施例９
実施例５において、電荷輸送材を前記のジスチリル系化合物（ＩＩＩ−２）から前記のジスチリル系化合物（ＩＩＩ−９２）に示す化合物に代えたこと以外は、実施例５と同様にして感光体を作製した。
【００８３】
比較例５
実施例５において、電荷発生材を前記製造実施例１で得られたチタニルオキシフタロシアニンから前記合成例１で得られたチタニルオキシフタロシアニンに代えたこと以外は、実施例５と同様にして感光体を作製した。
比較例６
実施例５において、電荷発生材を前記製造実施例１で得られたチタニルオキシフタロシアニンから前記製造比較例１で得られたチタニルオキシフタロシアニンに代えたこと以外は、実施例５と同様にして感光体を作製した。
【００８４】
比較例７
実施例５において、電荷発生材を前記製造実施例１で得られたチタニルオキシフタロシアニンから前記製造比較例２で得られたチタニルオキシフタロシアニンに代えたこと以外は、実施例５と同様にして感光体を作製した。
比較例８
実施例５において、電荷輸送材をジスチリル系化合物（ＩＩＩ−２）から１−フェニル−３−（ｐ−ジエチルアミノスチリル）−５−（ｐ−ジエチルアミノフェニル）−２−ピラゾリン（ＡＳＰＰ）に代えたこと以外は、実施例５と同様にして感光体を作製した。
【００８５】
比較例９
実施例５において、電荷輸送材をジスチリル系化合物（ＩＩＩ−２）からｐ−ジエチルアミノベンズアルデヒド−ジフェニルヒドラゾン（ＡＢＰＨ）に代えたこと以外は、実施例５と同様にして感光体を作製した。
このようにして得られた各感光体の特性を川口電機製作所製の静電気帯電試験装置ＥＰＡ−８１００を用いて評価した。暗所で、コロナ放電で、感光体表面を帯電する。コロナ放電電圧を実施例５の感光体表面の帯電位Ｖ_０が−６００Ｖに帯電できるように調整し、その放電電圧で各感光体表面を帯電して、帯電位Ｖ_０を測定し、続いて、コロナ放電を中止した状態で暗所に５秒間放置後、一般的なレーザープリンターに使用される半導体レーザーの発振波長が７６０ｎｍ〜８００ｎｍであることから、１００Ｗのハロゲンランプを光源として光学フィルターで単色光とした波長７８０ｎｍの光を感光体表面で０．７μＷ／ｃｍ^２になるように照射し、感光体表面の帯電位が１／２にまで減少する露光エネルギーＥ_１／２（μＪ／ｃｍ^２）で感度を評価し、さらに、照射５秒後の感光体表面の残留電位Ｖ_Ｒ５を測定した。また、コロナ放電電圧を上記設定電圧に維持し、上記帯電─露光の操作を連続して１００００回繰り返した後、Ｖ_０，Ｅ_１／２，Ｖ_Ｒ５を測定して、感光体の疲労特性を評価した。その結果を表５に示す。
【００８６】
【表５】

表５に見られるように、この発明のチタニルオキシフタロシアニン結晶とジスチリル系化合物とを組み合わせた感光体の優位性は明らかである。
実施例１０
導電性基体として、外径３０ｍｍ，内径２８ｍｍ，長さ２６０．３ｍｍ，表面粗さが最大高さＲ_ｍａｘで１．０μｍのアルミニウム円筒を用い、その上に下引き層を形成する。下引き層の材料としては下記のものを用いた。
【００８７】
Ａ：メラミン樹脂（三井東圧化学（株）製；商品名「ユーバン２０ＨＳ」）
Ｂ：酸類（芳香族カルボン酸，芳香族カルボン酸塩）
Ｂ１　　フタル酸
Ｂ２　　安息香酸アンモニウム
Ｃ：アジピン酸
Ｄ：ヨウ素
Ａ〜Ｄの材料を用い、ジクロロメタンとメタノールの１：１の混合溶媒を用いて、下記表６に示すような組成の下引き層塗布液を調製し、導電性基体上に浸漬塗布し、１２０℃で１時間乾燥して膜厚１５μｍの下引き層を形成した。
【００８８】
【表６】

これらの下引き層上に、前述の製造実施例１，２および製造比較例１，２で得られた各チタニルオキシフタロシアニン２部をそれぞれテトラヒドロフラン９７部に塩化ビニル−酢酸ビニル共重合樹脂（ユニオンカーバイド社製；商品名「ＶＭＣＨ」）を溶解した樹脂液とともにボールミルで６時間分散して調製した各塗布液を塗布し、１００℃で２時間乾燥して膜厚０．３μｍの電荷発生層を形成した。続いて、これらの電荷発生層上に、電荷輸送材としてのＮ，Ｎ−ジエチルアミノベンズアルデヒドジフェニルヒドラゾン１０部，ポリカーボネート樹脂（帝人（株）製；商品名「パンライトＫ−１３００）１０部を塩化メチレン１００部に溶解した液をそれぞれ塗布，乾燥して、膜厚２０μｍの電荷輸送層を形成して、下記表７に示すような１６種類の感光体を作製した。
【００８９】
【表７】

このようにして得られた各感光体の電気特性を感光体プロセス試験機で評価した。感光体を試験機に取り付け、周速７８．５ｍｍ／秒で回転させながら、暗所でコロトロンで感光体表面を帯電する。実施例１０の感光体表面の帯電位Ｖ_Ｄが−６００ｖとなるように放電電圧を設定し、その放電電圧で各感光体を帯電し、暗部電位Ｖ_Ｄを測定する。その後、暗所に５秒間放置後の電位を測定してその間の電位保持率Ｖ_Ｋ５（％）を求める。続いて、波長７８０ｎｍ，放射照度２μＷ／ｃｍ^２の光を照射し、０．２秒後の電位をもって明部電位Ｖ_Ｉとする。このような帯電，露光を１サイクルとするプロセスを１００００回繰り返し、初期と１００００回後の特性を評価した。その結果を表８に示す。
【００９０】
【表８】

表８に見られるように、下引き層にヨウ素を含まないものは、残留電位がいずれも高く、繰り返し特性も悪い。また、ヨウ素を含んでいても、芳香族カルボン酸の代わりに脂肪族カルボン酸を用いた感光体はＶ_ｉが高く繰り返し特性も悪い。下引き層に芳香族カルボン酸またはその塩を用い、かつ、ヨウ素を含んでいるものでも、電荷発生材に製造比較例２のチタニルフタロシアニンを用いたものは、残留電位が高く繰り返し特性も悪い。電荷発生材に製造比較例１のチタニルフタロシアニンを用いたものも繰り返しによる残留電位の上昇が大きい。
【００９１】
また、電気特性に及ぼす環境の影響を調べる。低温低湿（ＬＬ：温度１０℃，相対湿度５０％），高温高湿（ＨＨ：温度３５℃，相対湿度８５％）の各環境下で電気特性を測定した。その結果を表９に示す。
【００９２】
【表９】

表９に見られるように、下引き層に芳香族カルボン酸を用い、かつ、ヨウ素を含むものは、環境の変化によるＶ_Ｄ，Ｖ_Ｉの変動が少なく安定している。電荷発生材に製造比較例２のチタニルフタロシアニンを用いたものは、残留電位が高い。
次に、これらの感光体をレーザービームプリンター（ヒューレットパッカード社製：商品名「レーザージェットＩＩＩ）に搭載して、ＬＬ環境下，常温常湿（ＮＮ：温度２５℃，相対湿度５０％）環境下，ＨＨ環境下でそれぞれ印字を行い、画質を評価した。その結果を表１０に示す。なお、画質の評価は、感光体の表面の９０ｍｍ×９０ｍｍの正方形の面積中に存在する径が０．２ｍｍ以上の黒点の数で行い、５個未満を◎，５個以上２０個未満を○，２０個以上５０個未満を△，５０個以上を×とした。
【００９３】
【表１０】

表１０に見られるように、芳香族カルボン酸を用い、かつ、ヨウ素を含有する下引き層を用い、電荷発生材に本発明のチタニルオキシフタロシアニンを用いた感光体の優位性は明らかである。
【００９４】
【発明の効果】
この発明によれば、非晶質チタニルオキシフタロシアニンをイオン性物質を溶解した水溶液に温度５０℃以下（好ましくは３０℃以下）で機械的力（歪力，剪断力，衝撃力など）の存在下で分散，微粒子化した後、この系に非水溶性有機溶媒を加え、機械的力の存在下、水系に分散した前記チタニルオキシフタロシアニンを水分を除去しながら非水溶性有機溶媒系に移行させた後、非水溶性有機溶媒を除去することにより、ＣｕＫαを線源とするＸ線回折スペクトルにおいて、ブラッグ角（２θ±０．２°）７．２２°，９．６０°，１１．６０°，１３．４０°，１４．８８°，１８．３４°，２３．６２°，２４．１４°，および２７．３２°に明瞭な回折ピークを有し、かつ、前記ブラッグ角９．６０°における回折ピークが最大回折ピークであることを特徴とする、分散安定性に優れ、半導体レーザー光などの近赤外域の光に十分な感度を有し、かつ、電子写真に適した電気特性を安定的に有する新規なチタニルオキシフタロシアニン結晶が得られる。また、結晶格子定数（誤差範囲±１％）が、ａ＝１６．３０５８Å，ｂ＝２３．０７８Å，ｃ＝８．７１５５Å，α＝１０１．３５２°，β＝２３．０７８°，γ＝１１７．５３０°であることを特徴とする、上述と同様に優れた新規なチタニルオキシフタロシアニン結晶が得られる。
【００９５】
そして、積層型感光体の電荷発生層にこのような新規なチタニルオキシフタロシアニン結晶を電荷発生材として用いることにより、電気特性に優れ、半導体レーザー光のような近赤外域の波長光に十分な感度を有し、画像ノイズや画像濃度ムラなどの品質欠陥のない画像が得られ、繰り返し使用においても安定した電気特性，画像品質を維持できる感光体を得ることができる。
また、このような感光体の電荷輸送層に電荷輸送材としてヒドラゾン系化合物またはジスチリル系化合物を用いることにより、より改善された特性の感光体が得られる。
【００９６】
さらに、導電性基体と感光層の間に設けられる下引き層を、メラミン樹脂と芳香族カルボン酸および／または芳香族カルボン酸無水物のいずれかとこれらに固定されたヨウ素を主要成分として含む硬化膜、または、メラミン樹脂と芳香族カルボン酸および／または芳香族カルボン酸塩のいずれかとこれらに固定されたヨウ素を主要成分として含む硬化膜とすることにより、その上に電荷発生層を成膜ムラなく密着性良く塗布形成することができて、感光体の電気特性のばらつきがより改善され、また、画像欠陥がより低減され、さらに、感光体の電気特性の環境依存性が大幅に改善される。
【図面の簡単な説明】
【図１】この発明のチタニルオキシフタロシアニン結晶のＸ線回折スペクトル図
【図２】Ｉ型チタニルオキシフタロシアニン結晶（特開昭６２−６７０９４号公報記載）のＸ線回折スペクトル図
【図３】非晶質チタニルオキシフタロシアニン結晶のＸ線回折スペクトル図
【図４】α型チタニルオキシフタロシアニン結晶（特開昭６２−１３４６５１号公報記載）のＸ線回折スペクトル図
【図５】この発明のチタニルオキシフタロシアニン結晶，Ｉ型チタニルオキシフタロシアニン結晶およびα型チタニルオキシフタロシアニン結晶の光吸収スペクトル図
【図６】ＩＩ型チタニルオキシフタロシアニン結晶（特開昭６２−６７０９４号公報記載）のＸ線回折スペクトル図
【図７】この発明に係わる感光体の一実施例の模式的断面図
【符号の説明】
１　　　導電性基体
２　　　下引き層
３　　　感光層
４　　　電荷発生層
５　　　電荷輸送層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a titanyloxyphthalocyanine crystal having a novel feature, a method for producing the same, and a high sensitivity using such a titanyloxyphthalocyanine crystal as a charge generating material, in particular, high sensitivity to near infrared light such as semiconductor laser light. And an electrophotographic photoreceptor.
[0002]
[Prior art]
Electrophotography is an image forming method that skillfully combines photoconductivity and electrostatic phenomena, as disclosed by Carlson in US Pat. No. 2,297,691. Is uniformly charged in a dark place by corona discharge or the like, and then irradiates a light image of a document or the like, converts the light image into an electrostatic latent image using photoconductivity, and charges the charged electrostatic powder (toner ) Is applied to convert the image into a visible image, which is transferred and fixed on a support such as paper to obtain an image.
According to such an electrophotographic method, a laser or LED is used as an exposure light source, an original image is exposed and scanned, the image is decomposed into pixel units, and the surface of the photoreceptor is exposed and scanned in pixel units. Digital processing is possible. In addition, information can be printed out by changing the output of the information processing apparatus to light dots and exposing and scanning the surface of the photoconductor. Therefore, in recent years, with the advancement and speeding up of information processing, high-speed, high-quality optical printers and digital copiers using electrophotography have rapidly become widespread. In particular, when a semiconductor laser is used as a light source, an apparatus using a semiconductor laser as an exposure light source has been attracting attention because it is possible to achieve miniaturization, low cost, high reliability, and high image quality. Research and development of photoreceptors having high sensitivity have been actively conducted. Since the oscillation wavelength of semiconductor lasers currently in practical use is a relatively long wavelength in the near-infrared region, the photoreceptor used in an apparatus using a semiconductor laser as an exposure light source has a high light emission even in such a long wavelength region. It is required to have sensitivity. Further, even when used under various environments and when used repeatedly, it is required that there be no change in the electrical characteristics of the photoconductor, no change in the image quality of the output image, or memory generation.
[0003]
Conventionally, as charge generation materials sensitive to the oscillation wavelength of such a semiconductor laser having a relatively long wavelength, polyazo dyes, phthalocyanine dyes, azurenium salt dyes, pyrylium salt dyes, naphthoquinone dyes, and the like are known. ing. However, naphthoquinone-based dyes have relatively low sensitivity, and polyazo-based dyes are difficult to synthesize stably, and azulenium salt-based dyes and pyrylium salt-based dyes tend to change their photoconductive properties with humidity. Has the disadvantage that it is chemically structurally unstable to strong light such as laser light, and has been difficult to use. On the other hand, phthalocyanine dyes are chemically and physically stable dyes used as coloring pigments for inks and paints, and have been known to have properties as organic semiconductors from the beginning. In addition, the synthesis is relatively easy, and its light absorption ability extends to a long wavelength range. Its absorption wavelength and photoconductive properties can vary greatly depending on the type and crystal form of the central metal of phthalocyanine and its processing method. Was known. From such a viewpoint, phthalocyanine dyes are expected to have high sensitivity in a long wavelength region and good photoconductive properties, and have been widely studied as charge generation materials for electrophotographic photoreceptors.
[0004]
Examples of the phthalocyanine dye as a charge generating material include ε-type copper phthalocyanine, X-type metal-free phthalocyanine, τ-type metal-free phthalocyanine, chloroaluminum phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, chlorogermanium phthalocyanine, vanadyloxyphthalocyanine, Titanyloxyphthalocyanine and the like have been studied. However, metal-free phthalocyanine and divalent metal phthalocyanine do not provide sufficient sensitivity to near-infrared semiconductor laser light. In addition, trivalent or tetravalent metal phthalocyanine has sensitivity in a relatively long wavelength region, but phthalocyanine in which a halogen atom is bonded to a central metal is gradually hydrolyzed by atmospheric moisture to change electric characteristics. There is a disadvantage that. However, even a tetravalent metal phthalocyanine in which oxygen is bonded to a metal is stable against moisture, and thus titanyloxyphthalocyanine has recently attracted particular attention as a charge generating material and has been energetically studied.
[0005]
The electrophotographic photoreceptor includes a conductive substrate as a support, and a photosensitive layer formed thereon.
An example in which titanium phthalocyanine is used for an electrophotographic photosensitive member is described in JP-B-49-4338 as an example of a metal phthalocyanine used as a photoconductive material of a resin-dispersed single-layer photosensitive member. Recently, rather than a single-layer photoreceptor, the photosensitive layer was functionally separated into a charge generation layer containing a charge generation material as a main component and a charge transport layer containing a charge transport material as a main component. Such stacked photoreceptors have become mainstream because of their superior properties, but research on applying titanyloxyphthalocyanine as a charge generating material to the charge generating layer has been actively conducted. Is being done.
[0006]
For example, JP-A-59-49544 and JP-A-59-166959 describe that a deposited film of titanyloxyphthalocyanine is used for a charge generation layer. However, the method of forming the charge generation layer by the vapor deposition method is not preferable because the equipment investment such as a vacuum deposition apparatus is large and the cost is high because of poor mass productivity, so the charge generation material is dispersed in the solvent together with the binder. It is industrially desirable to form a charge generation layer by applying a dissolved liquid. However, a photoreceptor provided with a charge generation layer composed of a coating film formed by a coating method is inferior to a vapor deposition method in terms of electrical characteristics, image characteristics, and characteristic variations due to repeated use. That is, the photoreceptor formed by the coating method has lower chargeability and higher residual potential than the photoreceptor formed by vapor deposition, and the sensitivity is reduced by about 40% as compared with the vapor deposition method (for example, Example of JP-A-59-49544). The cause is that the dispersion stability of the charge generating material dispersed in the coating solution is poor, and the charge generating material is agglomerated or settled, so that the applied charge generating layer coating film is partially inhomogeneous. This is because the charge generation material does not work uniformly and effectively. Then, the sensitivity is reduced and the trapping of charge carriers is increased in a portion where the amount of the charge generating material is small, so that the sensitivity is fluctuated, an image is ghosted, and a memory is caused in repeated use. In addition, since the electrical properties of the area where the charge generating material is aggregated are different from the surroundings, this causes image noise.
[0007]
Therefore, in order to use these phthalocyanines as a charge generation material for a photosensitive layer formed by a photoreceptor coating method, not only electrical characteristics but also many required characteristics such as dispersion stability in a coating solution must be satisfied. No.
As electrical characteristics, not only high photosensitivity as an initial characteristic, but also good chargeability, low dark decay, and low residual potential are required, and these characteristics change with repeated use. It is required that the characteristics do not fluctuate due to the use environment. With respect to dispersion stability, it is required that the charge generation material does not cause aggregation, sedimentation, crystal growth, etc. in the coating solution for a long period of time.
[0008]
Although the electrical properties of phthalocyanine differ greatly depending on the type of coordinating metal of phthalocyanine, it is known that the same metal phthalocyanine has large differences in chargeability, dark decay, sensitivity, etc. due to the difference in crystal form (Manazawa Sawada: Dyes and Chemicals, Vol. 24, No. 6, p. 122 (1979)). On the other hand, it is known that the dispersion stability of a phthalocyanine pigment in an organic solvent varies depending on the size, shape, and zeta potential of the particle surface (Takeo Kumano: Journal of the Electrographic Society of Japan, Vol. 2, No. 2) , P111-120 (1984)). The shape of the particles and the surface potential of the particles are greatly affected not only by the crystal form but also by the difference in crystal habit based on the difference in the crystal growth surface. Therefore, when examining the charge generation material, it is important to develop a crystal form having good electrical properties and crystal grains having a crystal habit suitable for dispersion. However, in the development of conventional titanyloxyphthalocyanine, much attention has been paid to electrical properties, and much effort has been made in how to create a crystal form having good electrical properties. It was not noted.
[0009]
In the case where the crystal habit is different in the same crystal form, the difference is observed depending on the appearance. However, the X-ray diffraction spectrum can be easily identified from the difference in the intensity at the diffraction angle. Characteristic crystals of titanyloxyphthalocyanine classified based on the difference in the diffraction angle of the X-ray diffraction spectrum described in the patent specifications published so far include JP-A-61-217050 and JP-A-62-17050. 61-239248 and JP-A-62-134651, α-type, JP-A-62-67094, I and II types, JP-A-63-364, JP-A-63-366. The gazette describes A, B, and C type crystals, respectively. Japanese Patent Application Laid-Open No. 63-198067 discloses an m-type, and Japanese Patent Application Laid-Open No. 1-123868 discloses a quasi-amorphous type. By the way, in the crystal of titanyloxyphthalocyanine, those whose lattice constants are known from the structural analysis are C type, Phase I type and Phase II type. Phase II belongs to the triclinic system, and Phase I and C belong to the monoclinic system. When the crystal forms described in the above patent specification are analyzed from these known crystal lattice constants, the A type and I type belong to Phase I type, the α type and B type belong to Phase II type, and the m type Belongs to the C type (the literature explaining the same includes J. of Imaging Science and Technology Vol. 37, No. 6, 1993, p605 to p609).
[0010]
Further, in the disclosed crystal of titanyloxyphthalocyanine, in addition to the classification in which the above crystal form name is described, even when the exact crystal lattice constant is unknown, the diffraction peak intensity of the X-ray diffraction spectrum is Since the disclosed crystal forms are characterized by the combination of the intensity and the diffraction angle, titanyloxyphthalocyanine can be roughly classified into four groups in industrial use as follows. One is thermodynamically stable and is usually obtained immediately after synthesis, and has a maximum diffraction peak intensity at a Bragg angle of 26.3 ° (± 0.2 °) in an X-ray diffraction spectrum. These crystals include the type I described in the above-mentioned JP-A-62-67094. The second one has a maximum or main diffraction peak intensity at a Bragg angle of 27.3 ° (± 0.2 °) in an X-ray diffraction spectrum, as described in Japanese Patent Application Laid-Open No. 62-67094. Examples include the disclosed Type II. Third, it has the maximum diffraction peak intensity at a Bragg angle of 7.5 ° in the X-ray diffraction spectrum, and is disclosed in JP-A-61-239248 and JP-A-61-217050. Is mentioned. Fourth, in the X-ray diffraction spectrum disclosed in JP-A-5-320167, the Bragg angles are 9.5 °, 14.1 °, 17.8 °, 27.1 °, and 29.0. It has a clear diffraction peak at °° and further has the maximum diffraction peak intensity at 9.5 °.
[0011]
[Problems to be solved by the invention]
However, titanyloxyphthalocyanines of any of these categories have poor electrical sensitivity, poor charging properties, poor potential stability during repeated use, and potential degradation due to changes in the use environment. There are some points that are practically problematic in terms of characteristics.Furthermore, since the dispersion stability of the charge generating material coating liquid is not sufficient, the formation of the charge generating layer film immediately after dispersion and after aging is performed under the same coating conditions. In this case, there is a problem in terms of dispersion stability, such as different characteristics and image noise due to agglomerated particles, and the actual condition is that a satisfactory charge generation material has not yet been obtained. As a result, it has not been possible to obtain a photosensitive member that is truly industrially, economically or excellent in quality.
[0012]
In general, in a photoreceptor, a charge transporting material that is good for a certain charge generating material is not always good for another charge generating material, and that a good charge generating material for a certain charge generating material is good. The material is not always good with respect to other charge transport materials. That is, there is an appropriate combination of the charge generation material and the charge transport material. Inappropriate combinations may result in insufficient sensitivity, poor charging ability, poor stability of electrical characteristics during repeated use, and some practical problems. Therefore, although the combination of the charge generating material and the charge transporting material is very important, there is no clear theory on the combination, and the experiment must be repeated, and the optimal combination of the charge generating material and the charge transporting material is required. There was a problem that finding it was not easy.
[0013]
Further, in the case of a laminated photoreceptor, usually, in order to suppress the injection of charge carriers from the conductive substrate, the surface shape (roughness) and the variation of the property of the conductive substrate, or the contamination of the surface are covered. Then, in order to apply and form a good photosensitive layer having no film formation unevenness thereon, an undercoat layer containing a resin as a main component is provided between the conductive substrate and the photosensitive layer. As resins used for the undercoat layer, resins such as solvent-soluble polyamide, polyvinyl alcohol, polyvinyl butyral, and casein are known. These resins can sufficiently fulfill their purpose even with a thin film, for example, a film thickness of 0.1 μm or less, in order to simply suppress charge carrier injection. However, in order to cover the surface of the conductive substrate and form a photosensitive layer on which the film is not uneven, a film thickness of 0.5 μm or more is required. Depending on the case, a film thickness of 1 μm or more is required in some cases. However, when such a thick resin layer is formed of the above-mentioned resin such as polyvinyl alcohol, polyvinyl butyral, and casein, there arises a problem that the electric resistance of the layer increases and the residual potential of the photoconductor increases. In addition, there is a problem that the electrical characteristics of the photoreceptor fluctuate greatly under low-temperature, low-humidity, high-temperature, high-humidity environments. The problem is that the resin layer has a large water absorption, the amount of water contained in the resin layer fluctuates greatly depending on the environment, and the electric conductivity of the resin layer changes due to the dissociation of water in the resin layer. It occurs because of movement, that is, fluctuation due to moisture contained in the resin layer because it is determined by ion conduction.
[0014]
Conventionally, various materials have been proposed as materials having a low electric resistance and suitable as an undercoat layer even for a thick film layer as described above. For example, with respect to a solvent-soluble polyamide resin, JP-A-2-193152, JP-A-3-288157, JP-A-4-31870 and the like are known as those for specifying the resin structure. JP-A-3-145652 and JP-A-3-81788 disclose the use of a mixture of a polyamide resin and another resin, which is expected to have an effect of adjusting electric resistance and reducing the influence of environmental changes. And Japanese Patent Application Laid-Open No. 2-281262 are known. However, these materials are also mainly composed of polyamide resins, and the effects of temperature and humidity cannot be avoided.
[0015]
The present invention has been made in view of the above points, the first object is excellent in dispersion stability, having sufficient sensitivity to near-infrared wavelength light such as semiconductor laser light, and, An object of the present invention is to provide a titanyloxyphthalocyanine crystal having stable electric characteristics suitable for electrophotography. A second object is to provide a method for producing such a titanyloxyphthalocyanine crystal. The third object is to use such titanyloxyphthalocyanine as a charge generating material, thereby having excellent electrical characteristics, having sufficient sensitivity to near-infrared wavelength light such as semiconductor laser light, and reducing image noise and noise. An object of the present invention is to provide a photoreceptor capable of obtaining an image free from quality defects such as image density unevenness and maintaining stable electrical characteristics and image quality even in repeated use. A fourth object is to provide a charge transporting material that functions suitably in combination with the above-mentioned titanyloxyphthalocyanine. The fifth object is to form a charge generation layer containing the above-mentioned titanyloxyphthalocyanine as a main component, so that the undercoat layer can be formed by coating without unevenness in film formation and has a small variation in electric resistance with respect to environmental changes. To provide.
[0016]
[Means for Solving the Problems]
According to the present invention, the first problem described above is represented by the following general formula (I). In an X-ray diffraction spectrum using CuKα as a source, a Bragg angle (2θ ± 0.2) 7.22 °, Having clear diffraction peaks at 9.60 °, 11.60 °, 13.40 °, 14.88 °, 18.34 °, 23.62 °, 24.14 °, and 27.32 °, and Is solved by a titanyloxyphthalocyanine crystal having the maximum diffraction peak at a Bragg angle of 9.60 °.
[0017]
Embedded image

[In the formula (I), X ¹ , X ² , X ³ And X ⁴ Represents Cl or Br, respectively, and n, m, l and k each represent an integer of 0 to 4. ]
FIG. 1 is a diagram showing an example of an X-ray diffraction spectrum of such a titanyloxyphthalocyanine crystal.
In addition, the crystal lattice constant (error range ± 1%) represented by the general formula (I) is a = 16.3058 °, b = 23.078 °, c = 8.7155 °, α = 101.352 °, β = 23.078 °, γ = 117.530 ° with a titanyloxyphthalocyanine crystal.
[0018]
The titanyloxyphthalocyanine crystal as described above has a light absorption spectrum as shown in FIG. FIG. 5 also shows the light absorption spectra of α-type titanyloxyphthalocyanine and I-type titanyloxyphthalocyanine for comparison. It has an excellent light absorbing ability and is superior to the α-form, and has a strong absorbing ability up to a wavelength region of 820 nm or more. Therefore, by using the titanyloxyphthalocyanine crystal of the present invention as a charge generating material, it is possible to obtain a photosensitive member optimal for near-infrared wavelength light such as semiconductor laser light.
[0019]
Further, the titanyloxyphthalocyanine crystal of the present invention is very stable in the coating solution for the charge generation layer, hardly causes aggregation, precipitation, and crystal growth, and has excellent dispersion stability. Therefore, upon application of the charge generation layer, microscopic non-uniformity of the layer due to the presence of aggregated coarse charge generation material and non-uniform dispersion of the charge generation material does not occur. Since it is stable, it is not necessary to change the coating conditions over time in order to obtain a layer of stable quality, which facilitates the production of the photoreceptor. Also, in the obtained image of the photoconductor, the occurrence of image noise and image unevenness is eliminated.
The second problem is that the amorphous titanyloxyphthalocyanine is dispersed and atomized in an aqueous solution in which an ionic substance is dissolved at 50 ° C. or less in the presence of mechanical force, and then the water-insoluble organic Solved by employing a manufacturing method of adding a solvent, transferring titanyloxyphthalocyanine dispersed in an aqueous system to a water-insoluble organic solvent system while removing water in the presence of mechanical force, and then removing the water-insoluble organic solvent. You. The temperature of the aqueous solution in which the ionic substance is dissolved is more preferably 30 ° C. or lower, and the mechanical force includes a strain force, a shear force, an impact force, and the like.
[0020]
According to the classification according to the Bragg angle at which the maximum diffraction peak appears in the X-ray diffraction spectrum, the titanyloxyphthalocyanine crystal of the present invention is similar to that disclosed in JP-A-5-320167 (the fourth classification described above). However, the Bragg angles 7.22 °, 11.4 °, 13.4 °, 14.88 °, and 18.8 ° at which clear diffraction peaks appear are within the allowable error (2θ) described in JP-A-5-320167. (± 0.2 °), they are completely different from each other because they do not agree with each other, and can be said to be novel crystals. Further, as a result of the X-ray structural analysis, the crystal lattice constants were a = 16.3085 °, b = 23.078 °, c = 8.7155 °, α = 101.352 °, β = 23.078 °, γ = 117. It was found that the crystal form was a triclinic crystal form of 530 °, but such a crystal lattice constant was completely different from the crystal lattice constant of the conventionally known crystal form of titanyloxyphthalocyanine. It can be said that it is a crystal.
[0021]
Further, the third problem is solved by providing an electrophotographic photosensitive member containing, as a charge generating material, a crystalline form of titanyloxyphthalocyanine having the above-mentioned X-ray diffraction spectrum. Further, the problem can be solved by providing an electrophotographic photosensitive member containing, as a charge generating material, a crystalline form of titanyloxyphthalocyanine having the above-described crystal lattice constant.
The fourth problem is solved by using a hydrazone compound as a charge transport material in the charge transport layer. As the hydrazone-based compound, a compound represented by the following general formula (II) is preferable.
[0022]
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[In the formula (II), R ¹ , R ² , R ³ And R ⁴ Represents an alkyl group, an aralkyl group, or an aryl group, each of which may be substituted; ⁵ Represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group. Also, R ¹ And R ² May combine with each other to form a ring; ¹ And R ² One of R and R ⁵ May combine to form a ring. ]
The fourth problem can also be solved by using a distyryl compound as a charge transport material in the charge transport layer. As the distyryl-based compound, a compound represented by the following general formula (III) is preferable.
[0023]
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[In the formula (III), R ¹ , R ² , R ³ And R ⁴ Represents an aryl group or an alkyl group, each of which may be substituted; ⁵ And R ⁶ Represents a hydrogen atom, an alkyl group or an alkoxy group, and Ar represents an aryl group or an aromatic heterocyclic group which may be substituted. ]
By using the titanyl phthalocyanine crystal as described above as the charge generating material of the charge generating layer and using the above-mentioned hydrazone-based compound or distyryl-based compound as the charge transporting material of the charge transporting layer, the electrical characteristics are excellent and the sensitivity is higher. Thus, it is possible to obtain a photoreceptor capable of maintaining stable electric characteristics and image quality even in repeated use.
[0024]
A fifth object is to provide an electrophotographic photoreceptor comprising an undercoat layer provided on a conductive substrate and a photosensitive layer having a charge generation layer and a charge transport layer according to the present invention laminated thereon. This problem can be solved by providing a photoreceptor in which the coating layer is a cured film containing, as a main component, a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylic anhydride, and iodine fixed thereto. Alternatively, the problem is solved by providing a photoreceptor in which the undercoat layer is a cured film containing, as a main component, a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylate, and iodine fixed thereto.
[0025]
By making the cured film fixed by adding iodine into an undercoat layer in this manner, the melamine resin is simply converted into one of aromatic carboxylic acid and / or aromatic carboxylic anhydride, or aromatic carboxylic acid and And / or the surface of the conductive substrate is sufficiently covered and the charge generation layer is adhered to the surface without unevenness as compared with the case where the film cured with any one of the aromatic carboxylate is used as the undercoat layer. In order to be able to form a good coating with good performance, the residual potential is low even when the film is formed to be extremely thick, for example, in a thickness of 10 μm to 20 μm. In addition, it is possible to obtain an excellent photoreceptor having little variation in electrical characteristics and image characteristics even under a large environmental change. Although the reason is not yet clear at present, it is known that, for example, an adduct obtained by adding a large amount of iodine as much as 80% to 100% to nylon 6 has extremely low electric resistance (J. of Mat. Sci., 21 (1986) pp. 604 to 610), in addition to these systems, it is known that polyvinyl alcohol, polytetrahydrofuran, and acrylonitrile similarly form an adduct with iodine to obtain conductivity. However, as described above, any one of aromatic carboxylic acids and / or aromatic carboxylic acid anhydrides or any one of aromatic carboxylic acids and / or aromatic carboxylic acid salts is blended with the melamine resin. However, it has not been known that a cured film in which iodine is added and fixed can obtain good conductivity only by adding a small amount of iodine, and that the fluctuation is small even when the environment is largely changed. The present inventors have paid attention to this point, and by using such a cured film as an undercoat layer and combining the above-described novel titanyloxyphthalocyanine as a charge generating material, it is believed that the undercoat layer functions extremely effectively. I found it.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for producing the titanyloxyphthalocyanine crystal of the present invention will be illustratively described.
First, for example, o-phthalodinitrile, aminoiminoisoindolenin or alkoxyiminoisoindolenin and a titanium compound are reacted in an inert high boiling point solvent such as α-chloronaphthalene. The reaction is carried out at a temperature of from 160 to 300 ° C., preferably from 160 to 260 ° C.
Here, as the titanium compound, titanium halides such as titanium tetrachloride, titanium trichloride, and titanium tetrabromide and alkoxytitanium can be used, but titanium tetrachloride is preferable in terms of cost. However, titanium tetrachloride (TiCl ₄ )) Is used as a reaction reagent, the reaction is performed according to the following reaction formula, and in the first step, a reaction in an inert high boiling point solvent is carried out by dichlorotitanium phthalocyanine (PcTiCl2). ₂ ) Is produced and hydrolyzed in the second step to obtain titanyloxyphthalocyanine (PcTi = O). Here, Pc represents phthalocyanine.
[0027]
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Hereinafter, the production method will be described in more detail when a titanium halide is used as the titanium compound.
Examples of inert high-boiling solvents used in the reaction include dichlorobenzene, trichlorobenzene, α-chloronaphthalene, β-chloronaphthalene, diphenyl ether, α-methylnaphthalene, methoxynaphthalene, diphenylethane, ethylene glycol dialkyl ether, quinoline and the like. And an inert high-boiling organic solvent.
[0028]
The reaction temperature is usually from 160 ° C to 300 ° C, preferably from 180 ° C to 250 ° C. After the reaction, the generated dichlorotitanium phthalocyanine is filtered off and washed with the solvent used for the reaction to remove impurities generated during the reaction and unreacted raw materials.
Next, electron donation such as alcohols such as methanol, ethanol and isopropyl alcohol, ethers such as tetrahydrofuran and dioxane, amides such as dimethylformamide and N-methyl-2-pyrrolidone, sulfolane, dimethylsulfoxide, morpholine and pyridine. It is preferred to treat with a non-ionic solvent.
[0029]
Next, the dichlorotitanium phthalocyanine is heated in an aqueous solution to be hydrolyzed to obtain titanyloxyphthalocyanine. It is preferable that the titanyloxyphthalocyanine thus obtained is further purified to high purity. Examples of the purification method include a washing method, a recrystallization method, an extraction method such as Soxhlet, and a hot suspension method. Further, sublimation purification and the like are also possible. The purification method is not limited to these, and any method may be used as long as it can remove unreacted substances, reaction by-products and impurities.
Next, after dispersing or dissolving the titanyloxyphthalocyanine in concentrated sulfuric acid at a temperature of 5 ° C. or lower, the liquid is poured into a large amount of water at room temperature or lower. The precipitated titanyloxyphthalocyanine is separated by filtration, washed with sufficient water until neutral, and then dried. The X-ray diffraction spectrum of titanyloxyphthalocyanine obtained in this manner is close to an amorphous substance having a low crystallinity and showing no clear peak.
[0030]
Next, titanyloxyphthalocyanine thus obtained is dissolved in an aqueous solution in which an ionic substance is dissolved at a temperature of 50 ° C. or lower, preferably 30 ° C. or lower, in the presence of mechanical force such as strain force, shear force and impact force. Disperse and atomize. Next, a water-insoluble organic solvent is added to the system, and titanyloxyphthalocyanine dispersed in the water system is transferred to the non-aqueous solvent system while removing water in the presence of mechanical force. Next, the paste of titanyloxyphthalocyanine thus obtained is washed with a hydrophilic solvent such as methanol or acetone in which the organic solvent used is dissolved, and then the ionic substance is removed with water, followed by drying. Thus, a titanyloxyphthalocyanine crystal having excellent dispersibility and excellent electrophotographic properties according to the present invention can be obtained.
[0031]
Any ionic substance may be used as long as it becomes an ion when dissolved in water and imparts conductivity to water. Therefore, either an organic compound or an inorganic compound may be used. Examples of the inorganic compound include sodium chloride, sodium sulfate, sodium silicate, potassium chloride and the like. Examples of the organic compound include a carboxylic acid compound and a quaternized amine compound. However, inorganic compounds are preferred in view of economic efficiency, ease of purification, and the like.
As the water-insoluble organic solvent, a straight-chain aliphatic hydrocarbon, a branched aliphatic hydrocarbon, a cyclic hydrocarbon, or an aromatic hydrocarbon is selected. These compounds may have a substituent. As the substituent, a nitro group or a halogen group is preferable.
[0032]
Examples of the device for applying a mechanical force in the present invention include an attritor, a ball mill, a high-speed mixer, a Banbury mixer, a spec mixer, a roll mill, a three-roll, a nanomizer, a stamp mill, a planetary mill, a vibration mill, and a kneader. Can be If necessary, glass beads, steel beads, zirconia beads, alumina balls, zirconia balls, flint stone, etc. may be used as the dispersion medium.
FIG. 7 is a schematic sectional view of one embodiment of the photoreceptor according to the present invention using the titanyloxyphthalocyanine crystal thus obtained as a charge generating material. This is a photosensitive member having a so-called function-separated laminated structure in which a photosensitive layer 3 in which a charge generating layer 4 and a charge transporting layer 5 are laminated via the photoconductive layer 3 is provided. The undercoat layer 2 is provided as needed for the purpose of suppressing injection of charge carriers from the base, preventing unevenness in film formation of the photosensitive layer, improving adhesiveness, and the like.
[0033]
The conductive substrate may be any material as long as it has conductivity, and various materials may be used. Further, the shape may be any of a plate shape, a sheet shape, and a cylindrical shape, and is not particularly limited. For example, metal drums or metal sheets of aluminum, vanadium, nickel, copper, zinc, palladium, indium, tin, platinum, stainless steel, chromium, brass, etc .; plastic sheets on which these metals are deposited or laminated; For example, a plastic drum or a plastic sheet made of a conductive plastic or a material dispersed in a plastic is used.
[0034]
As the undercoat layer, one of melamine resin and aromatic carboxylic acid and / or aromatic carboxylic acid anhydride, or melamine resin and one of aromatic carboxylic acid and / or aromatic carboxylate is used. A cured film containing, as a main component, a kind or a mixture of two or more kinds and iodine fixed thereto is preferable.
The melamine resin according to the present invention is obtained by reacting melamine with formaldehyde to form a methylol compound, and further butyl etherifying with an alcohol. Further, aromatic carboxylic acid, aromatic carboxylic anhydride, and aromatic carboxylate include terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic acid, pyromellitic acid, pyromellitic anhydride, naphthalenecarboxylic acid, and benzoic acid. Acids and their ammonium salts and sulfates. These may be used alone or in combination of two or more.
[0035]
The total amount of the aromatic carboxylic acid added to the melamine resin is preferably 5 parts by weight to 100 parts by weight based on 100 parts by weight of the melamine resin. If the addition amount is less than 5 parts by weight, the degree of curing of the film decreases, and problems such as swelling and dissolution of the film occur when the charge generation layer is applied. It is not preferable because the life is shortened.
Further, a filler may be added to the undercoat layer in order to prevent sagging of the coating film and to prevent interference fringes on an image caused by light reflected from the base. As the filler, titanium oxide, aluminum oxide, kaolin, talc, silicon oxide or the like is used.
[0036]
The undercoat layer is preferably a cured film as described above, but is not limited to these cured films, and a layer made of a metal oxide such as alumite, which is conventionally known, or nylon 6, A layer made of a film-forming polymer resin such as polyamide 66 such as nylon 66, nylon 11, nylon 610, copolymerized nylon, and alkoxymethylated nylon, casein, polyvinyl alcohol, ethylene-acrylic acid copolymer, gelatin, and polyvinyl butyral; Alternatively, a layer made of a resin in which conductive, semiconductive or dielectric particles such as metal oxides such as zinc oxide, titanium oxide and aluminum oxide, silicon nitride, silicon carbide and carbon black are dispersed may be used.
[0037]
The charge generation layer is formed by applying a coating liquid in which a charge generation material is dispersed and dissolved in a solvent together with a binder. The charge generating material is preferably the titanyloxyphthalocyanine crystal of the present invention, but is not limited thereto, and another charge generating material may be used in combination. Examples of the charge generating material that can be used in combination are various metal-free phthalocyanines of various crystal forms, and various metal phthalocyanines such as iron, cobalt, nickel, aluminum, silicon, copper, titanium, vanadium, indium, gallium, germanium, magnesium, etc. , Bisazo, triazo compounds, anthraquinone compounds, perylene compounds, perinone compounds, azurenium salt compounds, squarium salt compounds, and pyrrolopyrrole compounds. The binder preferably used in the present invention is a film-forming polymer or copolymer which is hydrophobic and has high electrical insulation. Specifically, phenol resin, polyester resin, vinyl acetate resin, polycarbonate resin, polypeptide resin, cellulose resin, polyvinylpyrrolidone, polyethylene oxide, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate, styrene -Butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin , Polyvinyl alcohol, acrylic copolymer resin, methacrylic copolymer resin, silicone resin, methacrylonitrile copolymer resin, polyvinyl butyral, polyvinylidene chloride resin, etc. It is. These may be used alone or in combination of two or more. The thickness of the charge generation layer is 0.01 μm to 5 μm.
[0038]
The charge transporting layer is a layer containing a substance having a hole transporting ability. As the hole transporting material, a hydrazone-based compound or a distyryl-based compound is used. As the hydrazone-based compound, a compound represented by the general formula (II) is preferable. Typical examples are shown below.
[0039]
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[0040]
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[0041]
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[0042]
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Further, as the distyryl-based compound, a compound represented by the general formula (III) is preferable. Typical examples are shown below.
[0043]
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[0044]
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[0045]
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[0046]
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[0047]
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[0048]
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[0049]
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[0050]
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[0051]
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[0052]
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[0053]
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[0054]
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[0055]
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[0056]
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[0057]
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[0058]
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However, the hole transporting material that can be used is not limited to the above-described compounds, and various conventionally known substances can be used. For example, it is described in U.S. Pat. No. 4,150,987, U.S. Pat. No. 4,278,747, West German Patent Publication No. 2939483, British Patent Publication No. 2034493, European Patent Publication No. 13172, and the like. Such hydrazone-based compounds, pyrazoline-based compounds as described in JP-A-49-105536, and oxadi-based compounds as described in JP-A-54-112637 and U.S. Pat. Azole compounds, styryl compounds as referred to in JP-A-50-31733, U.S. Pat. No. 3,567,450, JP-B-49-35702, West German Patent No. 1110518, U.S. Pat. No. 3,180,703, U.S. Pat. No. 3,240,597, U.S. Pat. No. 3,658,520, U.S. Pat. No. 4,232,103, U.S. Pat. No. 4,175,961, U.S. Pat. No. 4,012,376, JP-A-55-144250, JP-A-56-119132, and Tokubo Sho. Arylamine compounds described in JP-A-39-27577, oxazole-based compounds described in U.S. Pat. No. 3,542,546, U.S. Pat. No. 3,180,729, JP-A-49-105536. And pyrazolone compounds as described in U.S. Pat. No. 3,615,402, U.S. Pat. No. 3,820,899, U.S. Pat. No. 3,542,544, JP-B-45-555, JP-B-51-10983. Polyarylalkane-based compounds as described in Japanese Patent Application Publication Polyvinylcarbazole and derivatives thereof as described in JP-B-34-10966, a polymer of N-acrylamidomethylcarbazole as described in JP-A-50-85337, JP-A-50-93432 6-vinylindolo (2,3-6) quinoxaline polymer as described in JP-B-43-187, vinyl polymers as described in JP-B-43-18674 and JP-B-43-19192, Triphenylmethane polymers described in JP-A-56-90883 and JP-A-56-161550; styrene copolymers and polyacenaphthenes described in JP-B-43-19193; Polyindene, a copolymer of acenaphthylene and styrene, described in JP-B-56-13940. Such as formaldehyde-based condensation resins. These hole transporting materials may form a charge transporting layer by applying a solution when the material itself has a film forming property. Is applied with a solution dissolved together with a resin having a film forming property to form a charge transport layer. The charge transport layer has a thickness of 5 μm to 40 μm.
[0059]
Further, the above-mentioned photosensitive layer may contain an electron-accepting substance, if necessary, for the purpose of improving the sensitivity, reducing the residual potential, or reducing the fluctuation of the characteristics upon repeated use. Examples of such an electron accepting substance include succinic anhydride, maleic anhydride, dibromo succinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, and pyromellitic anhydride. Examples thereof include compounds having a high electron affinity such as acids, trimellitic acid, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranil, bromanyl, and o-nitrobenzoic acid.
[0060]
The photosensitive layer may contain a deterioration inhibitor such as an antioxidant or a light stabilizer for the purpose of improving environmental resistance and stability against harmful light. Compounds used for such purposes include chromanol derivatives such as tocopherol and their etherified or esterified compounds, polyarylalkane compounds, hydroquinone derivatives and their monoetherified or dietherified compounds, benzophenone derivatives, benzotriazole derivatives Thioether compounds, phenylenediamine derivatives, phosphonate esters, phosphite esters, phenol compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, hindered amine compounds, and the like.
[0061]
Each of the above-mentioned layers is formed by using a commonly known coating apparatus such as a dip coater, a spray coater, a wire bar coater, an applicator, a doctor blade, a roller coater, a curtain coater, and a bead coater.
[0062]
【Example】
Hereinafter, specific examples of the present invention will be described. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.
First, an example of a method for producing titanyloxyphthalocyanine of the present invention will be described.
[Synthesis example 1 of titanyloxyphthalocyanine]
128 parts of phthalodinitrile is placed in a two-liter four-necked flask equipped with a stirrer and a cooler, 1000 parts of quinoline is added thereto, and 47.5 parts of titanium tetrachloride are added dropwise under a nitrogen atmosphere. After the dropwise addition, the mixture was heated and reacted at 200 ° C. ± 10 ° C. for 8 hours while heating, then allowed to cool, filtered while hot at 130 ° C., and washed with 500 parts of quinoline heated to 130 ° C. Further, the filtrate is sufficiently washed with N-methyl-2-pyrrolidone heated to 130 ° C. until the filtrate becomes transparent. Next, washing is performed in order of methanol and water, and washing is performed until the solvent in the wet cake disappears. The obtained wet cake is dispersed in 1000 parts of a 3% aqueous solution of caustic soda, heated for 4 hours, and washed with filtered water until the filtrate becomes neutral. Next, the cake is dispersed in 1000 parts of a 3% hydrochloric acid aqueous solution, heated for 4 hours, and washed with water until the filtrate becomes neutral. Further, it is washed with methanol and acetone. This operation of purifying alkali, acid, methanol and acetone is repeated several times until the filtrate with methanol and acetone becomes completely colorless, and then dried. The yield was 101.2 parts. As a result of FDMS analysis of the titanyloxyphthalocyanine thus obtained, only a single peak was observed at 576, which is the molecular weight of titanyloxyphthalocyanine, and titanyloxyphthalocyanine was free from impurities. FIG. 2 shows an X-ray diffraction spectrum of the titanyloxyphthalocyanine. This crystal form was type I described in JP-A-62-67094.
[0063]
[Crystal Conversion Example 1 of Titanyloxyphthalocyanine]
50 parts of titanyloxyphthalocyanine obtained in Synthesis Example 1 described above was gradually added to 750 parts of concentrated sulfuric acid at -10 ° C or lower while cooling and stirring so that the liquid temperature did not reach -5 ° C or higher. After the solution was further stirred for 2 hours, it was added dropwise to ice water at 0 ° C. After the precipitated blue substance was filtered and water-soluble, the cake was dispersed in 500 parts of a 2% aqueous sodium hydroxide solution and heated, and then washed with water until the filtrate became completely neutral, and then dried. The yield of the obtained titanyloxyphthalocyanine was 47 parts, and its X-ray diffraction spectrum was amorphous with almost no diffraction intensity as shown in FIG.
[0064]
[Production Example 1 of Titanyloxyphthalocyanine Crystal]
A mixture of 40 parts of amorphous titanyloxyphthalocyanine, 100 parts of salt and 400 parts of water obtained in Crystal Conversion Example 1 was placed in a sand mill filled with zirconia beads (manufactured by Shinmaru Enterprises Co., Ltd .; trade name “Dynomill”). At room temperature for 3 hours to form fine particles. Next, 200 parts of dichlorotoluene is added, and the operation of the sand mill is further continued. During operation, titanyloxyphthalocyanine gradually transitions from an aqueous system to an oil system. In this way, dispersion and fine-particle formation were performed for 3 hours after removing the separated water. Next, the content is taken out, dichlorotoluene is distilled off by steam distillation, and the remaining titanyloxyphthalocyanine is filtered with water, and then dried. The X-ray diffraction spectrum of the obtained titanyloxyphthalocyanine was as shown in FIG. 1, and the Bragg angles (2θ ± 0.2 °) 7.22 °, 9.60 °, 11.60 °, 13.40. °, 14.88 °, 18.34 °, 23.62 °, 24.14 °, and 27.32 ° have clear diffraction peaks, and the 9.60 ° diffraction peak is the maximum diffraction peak. And the titanyloxyphthalocyanine crystal of the present invention. The crystal lattice constant (error range ± 1%) of the titanyloxyphthalocyanine crystal is as follows: a = 16.308 °, b = 23.078 °, c = 8.7155 °, α = 101.352 °, β = 23.078. ° and γ = 117.530 °.
[0065]
[Production Example 2 of Titanyloxyphthalocyanine Crystal]
A mixture of 40 parts of amorphous titanyloxyphthalocyanine, 100 parts of sodium chloride and 400 parts of water obtained in Crystal Conversion Example 1 was dispersed and atomized in a sand mill similar to that of Production Example 1 at room temperature for 3 hours. Next, after transferring the contents to a biaxial kneader, 20 parts of α-dichloronaphthalene are added, and the kneader is operated. During operation, titanyloxyphthalocyanine gradually shifts from an aqueous system to an oil system. In this way, dispersion and fine-particle formation were performed for 3 hours while removing the separated water. Next, the content is taken out, α-dichloronaphthalene is distilled off by steam distillation, and the remaining titanyloxyphthalocyanine is filtered with water, and then dried. Thus, a titanyloxyphthalocyanine crystal of the present invention having an X-ray diffraction spectrum as shown in FIG. 1 was obtained in the same manner as in Production Example 1.
[0066]
[Production Example 3 of Titanyloxyphthalocyanine Crystal]
A mixture of 40 parts of amorphous titanyloxyphthalocyanine, 100 parts of salt, and 400 parts of water obtained in Crystal Conversion Example 1 was dispersed and atomized at room temperature for 3 hours in a ball mill filled with zirconia balls. Next, 200 parts of dichlorotoluene is added, and the operation of the ball mill is continued. During operation, titanyloxyphthalocyanine gradually shifts from an aqueous system to an oil system. In this way, dispersion and fine-particle formation were performed for 8 hours while removing separated water. Next, the content is taken out, dichlorotoluene is distilled off by steam distillation, and the remaining titanyloxyphthalocyanine is filtered with water, and then dried. Thus, titanyloxyphthalocyanine of the present invention having an X-ray diffraction spectrum as shown in FIG. 1 was obtained in the same manner as in Production Example 1.
[0067]
[Production Comparative Example 1 of Titanyloxyphthalocyanine Crystal]
The crystal conversion of titanyloxyphthalocyanine is carried out according to Synthesis Example 1 of the example of JP-A-2-131243. That is, 5 g of titanyloxyphthalocyanine was stirred in 100 g of 90% sulfuric acid at a temperature of 3 ° C. to 5 ° C. for 2 hours and then filtered, and the obtained sulfuric acid solution was dropped into 3 liters of water to take out precipitated crystals. The crystals were repeatedly washed with deionized water until the filtrate became neutral. O-dichlorobenzene was added as a dispersion medium to the thus obtained wet cake, and milling was performed at room temperature with a sand grinder. Subsequently, the dispersion medium was removed and washing was performed with acetone and methanol to obtain clear blue crystals. The X-ray diffraction spectrum of the obtained titanyloxyphthalocyanine crystal has a maximum diffraction peak at a Bragg angle (2θ) of 27.3 °, and a maximum diffraction peak at 6.8 ° within the range of 6 ° to 8 °. And the same crystal form as described in the specification of JP-A-2-131243.
[0068]
[Production Comparative Example 2 of Titanyloxyphthalocyanine Crystal]
Α-type titanyloxyphthalocyanine was produced by the method disclosed in JP-A-62-134651. That is, a mixture of 40 g of phthalodinitrile, 18 g of titanium tetrachloride and 500 cc of α-chloronaphthalene was heated and stirred under a nitrogen atmosphere at a temperature of 240 ° C. to 250 ° C. for 3 hours to complete the reaction, and then filtered to dichlorotitanium phthalocyanine. Got. A mixture of the obtained dichlorotitanium phthalocyanine and 300 cc of concentrated aqueous ammonia was heated under reflux for 1 hour, and then purified by Soxhlet extraction with acetone and dried to obtain titanyloxyphthalocyanine. This titanyloxyphthalocyanine was confirmed to be an α-type crystal having an X-ray diffraction spectrum as shown in FIG.
[0069]
[Dispersion stability of coating solution for charge generation layer, appearance of charge generation layer, and photoconductor image]
Next, using the various titanyloxyphthalocyanines obtained as described above, a coating solution for a charge generation layer was prepared, and a film was formed by a change in dispersion state immediately after the preparation and after standing for 3 weeks, and a dip coating method. The external appearance of the charge generation layer is observed, and the images of the respective photoconductors prepared using the coating solution for the charge generation layer immediately after preparation and after standing for 3 weeks are evaluated.
As described above, 2 parts of each titanyloxyphthalocyanine obtained in Production Example 1, Synthesis Example 1, Production Comparative Example 2, and Production Comparative Example 1 were combined with 97 parts of tetrahydrofuran in a vinyl chloride-vinyl acetate copolymer resin (manufactured by Union Carbide; It was dispersed in a ball mill for 6 hours together with a resin solution in which a trade name “VMCH” was dissolved, and the charge generation layer coating solution No. 1 shown in Table 1 below was used. 1 to No. 4 was prepared.
[0070]
[Table 1]

With respect to these charge generation layer coating liquids, the coating liquid dispersion state immediately after preparation and after standing for 3 weeks was visually observed and evaluated.
Next, on an outer peripheral surface of an aluminum cylinder having an outer diameter of 30 mm, 10 parts of a copolymerized polyamide resin (manufactured by Toray Industries, Ltd .; trade name "Amilan CM-8000") was mixed and dissolved with 190 parts of ethanol in a ball mill for 3 hours. The coating solution was applied with a wire bar coater and dried at a temperature of 100 ° C. for 1 hour to form a 0.5 μm-thick undercoat layer. On the undercoat layer, the above-mentioned coating solutions for various charge generation layers immediately after preparation and those after standing for 3 weeks were respectively applied, dried at a temperature of 100 ° C. for 2 hours, and dried to a thickness of 0.3 μm. The charge generation layer was formed, and the appearance was visually observed and evaluated. Subsequently, 10 parts of 1-phenyl-1,2,3,4-tetrahydroquinoline-6-carbaldehyde-1 ′, 1′-diphenylhydrazone as a charge transport material and a polycarbonate resin (manufactured by Teijin Chemicals Limited; A coating solution prepared by dissolving 10 parts of “Panlite K-1300” in 100 parts of methylene chloride was coated on each of the charge generation layers and dried to form a charge transport layer having a thickness of 15 μm. 1 to No. 4 were prepared.
[0071]
The image of each of the photoconductors thus manufactured was evaluated using a commercially available semiconductor laser beam printer.
Table 2 shows the results of the above observations and evaluations.
[0072]
[Table 2]

As can be seen from Table 2, the coating solution for a charge generation layer of the present invention did not cause aggregation or sedimentation of the charge generation material even after standing for 3 weeks. Without changing the coating conditions, a good charge generation layer free of aggregates and coating unevenness was obtained, and the image on the photoreceptor was excellent in image quality without defects caused by aggregates and coating unevenness. No memory was observed.
[Photoconductor production and characteristic evaluation]
Next, the above-mentioned various titanyloxyphthalocyanines are used as a charge generating material, the charge transporting material used in combination with the charge generating material is changed, and the undercoat layer is changed, to fabricate a photoreceptor and evaluate its characteristics. For evaluation of electrical characteristics, a flat photosensitive member was prepared.
[0073]
Example 1
A coating solution obtained by mixing and dissolving 10 parts of a copolyamide resin (manufactured by Toray Industries, Inc., trade name “Amilan CM-8000”) with 190 parts of ethanol in a ball mill for 3 hours on an aluminum substrate using a wire bar coater. The coating was dried at a temperature of 100 ° C. for 1 hour to form an undercoat layer having a thickness of 0.5 μm. On the undercoat layer, the above-mentioned coating solutions for charge generation layers were respectively applied, and dried at a temperature of 100 ° C. for 2 hours to form a charge generation layer having a thickness of 0.3 μm. Subsequently, 10 parts of 1-phenyl-1,2,3,4-tetrahydroquinoline-6-carbaldehyde-1 ′, 1′-diphenylhydrazone as a charge transport material and a polycarbonate resin (manufactured by Teijin Chemicals Limited; A coating solution prepared by dissolving 10 parts of “Panlite K-1300” in 100 parts of methylene chloride was coated on each of the charge generation layers and dried to form a 15 μm-thick charge transport layer. -1 and Comparative Examples 1-1, 1-2 and 1-3 were prepared.
[0074]
The electrical characteristics were measured using an electrostatic recording paper tester SP-428 manufactured by Kawaguchi Electric Works. In a dark place, the surface of the photoconductor of Example 1-1 was charged V by corona discharge of corotron method. ₀ Is adjusted to −600 V, and the surface of each photoreceptor is charged with the discharge voltage to obtain a charged potential V. ₀ Then, after stopping the corona discharge and leaving it in a dark place for 5 seconds, since the oscillation wavelength of a semiconductor laser used for a general laser printer is 760 nm to 800 nm, a 500 w xenon lamp is used as a light source. The surface of each photoreceptor is irradiated with light having a wavelength of 780 nm, which is converted into monochromatic light by a monochromator, and the exposure energy E at which the surface potential is reduced to half. _1/2 (ΜJ / cm ² ) To evaluate the sensitivity, and the residual potential V after 5 seconds of irradiation. _R5 Is measured. Next, the corona discharge voltage was maintained at the above-mentioned set voltage, and the above operation of charging / exposure was continuously repeated 10,000 times. ₀ , E _1/2 And V _R5 Was similarly measured to evaluate the fatigue characteristics of the photoreceptor. Table 3 shows the results.
[0075]
[Table 3]

As can be seen from Table 3, the photoconductor of Example 1-1 using the titanyloxyphthalocyanine crystal of Production Example 1 has the highest sensitivity and good fatigue characteristics. The superiority of the titanyloxyphthalocyanine crystal of the present invention as a charge generating material is apparent.
Example 2
An undercoat layer was formed on a substrate in the same manner as in Example 1. On this undercoat layer, a ball mill was used together with a resin solution prepared by dissolving 2 parts of titanyloxyphthalocyanine obtained in Production Example 1 described above and 97 parts of tetrahydrofuran in a vinyl chloride-vinyl acetate copolymer resin (manufactured by Union Carbide; VMCH). The coating solution for the charge generation layer prepared by dispersing for 6 hours was applied and dried at a temperature of 100 ° C. for 2 hours to form a charge generation layer having a thickness of 0.3 μm. On this charge generation layer, 10 parts of the above-mentioned hydrazone compound (II-5) as a charge transport material and 10 parts of a polycarbonate resin (manufactured by Teijin Chemicals Ltd .; trade name: “Panlite K-1300”) were salted. A solution dissolved in 100 parts of methylene was applied and dried to form a charge transport layer having a thickness of 15 μm, thereby producing a photoreceptor.
[0076]
Example 3
A photoconductor was prepared by the same way as that of Example 2 except that the charge transport material was changed from the hydrazone compound (II-5) to the hydrazone compound (II-9).
Example 4
A photoconductor was prepared by the same way as that of Example 2 except that the charge transport material was changed from the hydrazone compound (II-5) to the hydrazone compound (II-15).
[0077]
Comparative Example 1
A photoconductor was prepared in the same manner as in Example 2 except that the charge generating material was changed from the titanyloxyphthalocyanine obtained in Production Example 1 to the titanyloxyphthalocyanine obtained in Synthesis Example 1 in Example 2. Produced.
Comparative Example 2
A photoconductor was prepared in the same manner as in Example 2 except that the charge generating material was changed from the titanyloxyphthalocyanine obtained in Production Example 1 to the titanyloxyphthalocyanine obtained in Production Comparative Example 1. Was prepared.
[0078]
Comparative Example 3
Photoconductor in Example 2, except that the charge generating material was changed from titanyloxyphthalocyanine obtained in Production Example 1 to titanyloxyphthalocyanine obtained in Production Comparative Example 2, Was prepared.
Comparative Example 4
A photoconductor was prepared by the same way as that of Example 2 except that the charge transport material was changed from the hydrazone-based compound (II-5) to a compound represented by the following structural formula (H-1). .
[0079]
Embedded image

The characteristics of the photoconductors of Examples 2 to 4 and Comparative Examples 1 to 4 manufactured as described above were evaluated in accordance with Example 1. Table 4 shows the results.
[0080]
[Table 4]

As can be seen from Table 4, the superiority of the photoreceptor by combining the titanyloxyphthalocyanine crystal of the present invention with a hydrazone compound is apparent.
Example 5
In the same manner as in Example 2, up to the charge generation layer was formed on the substrate. On the charge generation layer, 10 parts of the distyryl compound (III-2) as a charge transport material and 10 parts of a polycarbonate resin (trade name “Panlite K-1300” manufactured by Teijin Chemicals Ltd.) were chlorided. A coating solution dissolved in 100 parts of methylene was applied and dried to form a charge transport layer having a thickness of 15 μm, thereby producing a photoreceptor.
[0081]
Example 6
A photoconductor was prepared by the same way as that of Example 5 except that the charge transport material was changed from the distyryl compound (III-2) to the distyryl compound (III-19) in Example 5. Produced.
Example 7
A photoconductor was prepared by the same way as that of Example 5 except that the charge transporting material was changed from the above distyryl compound (III-2) to the above distyryl compound (III-50). Produced.
[0082]
Example 8
A photoconductor was prepared by the same way as that of Example 5 except that the charge transport material was changed from the above distyryl compound (III-2) to the above distyryl compound (III-74). Produced.
Example 9
A photoconductor was prepared by the same way as that of Example 5 except that the charge transport material was changed from the above distyryl compound (III-2) to the above distyryl compound (III-92). Produced.
[0083]
Comparative Example 5
A photoconductor was prepared by the same way as that of Example 5 except that the charge generating material in Example 5 was changed from the titanyloxyphthalocyanine obtained in Production Example 1 to titanyloxyphthalocyanine obtained in Synthesis Example 1, and Produced.
Comparative Example 6
A photoconductor was prepared in the same manner as in Example 5 except that the charge generating material was changed from the titanyloxyphthalocyanine obtained in Production Example 1 to the titanyloxyphthalocyanine obtained in Comparative Example 1 above. Was prepared.
[0084]
Comparative Example 7
A photoconductor was prepared in the same manner as in Example 5, except that the charge generating material was changed from the titanyloxyphthalocyanine obtained in Production Example 1 to the titanyloxyphthalocyanine obtained in Comparative Production Example 2. Was prepared.
Comparative Example 8
In Example 5, the charge transport material was changed from the distyryl compound (III-2) to 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) -2-pyrazoline (ASPP). A photoconductor was prepared in the same manner as in Example 5, except for the above.
[0085]
Comparative Example 9
A photoconductor was prepared by the same way as that of Example 5 except that the charge transport material was changed from distyryl compound (III-2) to p-diethylaminobenzaldehyde-diphenylhydrazone (ABPH).
The characteristics of each photoconductor thus obtained were evaluated using an electrostatic charging tester EPA-8100 manufactured by Kawaguchi Electric Works. In a dark place, the surface of the photoconductor is charged by corona discharge. The corona discharge voltage was changed to the charged potential V on the photoreceptor surface in Example 5. ₀ Is adjusted so that it can be charged to -600 V, and the surface of each photoreceptor is charged with the discharge voltage. ₀ Then, after leaving for 5 seconds in a dark place in a state where the corona discharge is stopped, since the oscillation wavelength of a semiconductor laser used for a general laser printer is 760 nm to 800 nm, a 100 W halogen lamp is used. A light having a wavelength of 780 nm converted to monochromatic light by an optical filter as a light source is 0.7 μW / cm on the surface of the photoreceptor. ² And the exposure energy E at which the charged potential on the photoreceptor surface is reduced to half. _1/2 (ΜJ / cm ² ), And the residual potential V on the surface of the photoreceptor 5 seconds after the irradiation. _R5 Was measured. Further, the corona discharge voltage was maintained at the above-mentioned set voltage, and the above operation of charging / exposure was continuously repeated 10,000 times. ₀ , E _1/2 , V _R5 Was measured to evaluate the fatigue characteristics of the photoreceptor. Table 5 shows the results.
[0086]
[Table 5]

As can be seen from Table 5, the superiority of the photoreceptor in which the titanyloxyphthalocyanine crystal of the present invention is combined with a distyryl compound is apparent.
Example 10
Outer diameter 30 mm, inner diameter 28 mm, length 260.3 mm, maximum surface roughness R as conductive substrate _max A 1.0 μm aluminum cylinder is used, and an undercoat layer is formed thereon. The following materials were used as the material of the undercoat layer.
[0087]
A: Melamine resin (manufactured by Mitsui Toatsu Chemicals, Inc .; trade name “Uban 20HS”)
B: Acids (aromatic carboxylic acid, aromatic carboxylate)
B1 phthalic acid
B2 Ammonium benzoate
C: adipic acid
D: Iodine
Using the materials A to D, an undercoat layer coating solution having the composition shown in Table 6 below was prepared using a mixed solvent of dichloromethane and methanol at a ratio of 1: 1. After drying at 1 ° C. for 1 hour, an undercoat layer having a thickness of 15 μm was formed.
[0088]
[Table 6]

On these subbing layers, 2 parts of each titanyloxyphthalocyanine obtained in the above-mentioned Production Examples 1 and 2 and Comparative Examples 1 and 2 were added to 97 parts of tetrahydrofuran, respectively, with a vinyl chloride-vinyl acetate copolymer resin (Union Carbide). A coating solution prepared by dispersing in a ball mill for 6 hours together with a resin solution in which a product name “VMCH” was dissolved was applied and dried at 100 ° C. for 2 hours to form a 0.3 μm-thick charge generating layer. did. Subsequently, 10 parts of N, N-diethylaminobenzaldehyde diphenylhydrazone as a charge transporting material and 10 parts of a polycarbonate resin (manufactured by Teijin Limited; trade name “Panlite K-1300”) were charged on these charge generating layers with methylene chloride. The solutions dissolved in 100 parts were respectively applied and dried to form a charge transport layer having a thickness of 20 μm, thereby producing 16 types of photoconductors as shown in Table 7 below.
[0089]
[Table 7]

The electrical characteristics of each photoreceptor thus obtained were evaluated using a photoreceptor process tester. The photoconductor is mounted on a tester, and the surface of the photoconductor is charged with a corotron in a dark place while rotating at a peripheral speed of 78.5 mm / sec. Charge potential V on photoreceptor surface in Example 10 _D Is set to −600 V, each photosensitive member is charged with the discharge voltage, and the dark portion potential V _D Is measured. Then, the potential after being left in a dark place for 5 seconds was measured, and the potential holding ratio V during that time was measured. _K5 (%). Subsequently, a wavelength of 780 nm and an irradiance of 2 μW / cm ² Of light, and the potential after 0.2 seconds has a bright portion potential V _I And Such a process of one cycle of charging and exposure was repeated 10,000 times, and the characteristics at the initial stage and after 10,000 cycles were evaluated. Table 8 shows the results.
[0090]
[Table 8]

As can be seen from Table 8, those having no iodine in the undercoat layer have high residual potential and poor repetition characteristics. Further, even if iodine is contained, a photoconductor using an aliphatic carboxylic acid instead of an aromatic carboxylic acid has a V _i And high repetition characteristics. Even if the undercoat layer contains an aromatic carboxylic acid or a salt thereof and contains iodine, the charge generation material using the titanyl phthalocyanine of Production Comparative Example 2 has a high residual potential and poor repeatability. Also in the case of using the titanyl phthalocyanine of Production Comparative Example 1 as the charge generating material, the residual potential increased significantly due to repetition.
[0091]
In addition, the effect of the environment on the electrical characteristics is examined. The electrical characteristics were measured in each environment of low temperature and low humidity (LL: temperature 10 ° C., relative humidity 50%) and high temperature and high humidity (HH: temperature 35 ° C., relative humidity 85%). Table 9 shows the results.
[0092]
[Table 9]

As can be seen from Table 9, when the undercoat layer used an aromatic carboxylic acid and contained iodine, _D , V _I Fluctuations are small and stable. In the case of using the titanyl phthalocyanine of Production Comparative Example 2 as the charge generating material, the residual potential is high.
Next, these photoconductors are mounted on a laser beam printer (manufactured by Hewlett-Packard Company, trade name: “Laser Jet III”), and under LL environment, normal temperature and normal humidity (NN: temperature 25 ° C., relative humidity 50%) environment. , And HH, the image quality was evaluated, and the image quality was evaluated, and the results are shown in Table 10. The image quality was evaluated in such a manner that the diameter existing in a 90 mm × 90 mm square area on the surface of the photoreceptor was 0.1 mm. The number of black spots of 2 mm or more was evaluated as ◎, less than 5 as ◎, 5 or more as less than 20 as ，, 20 or more as less than 50 as Δ, and 50 or more as x.
[0093]
[Table 10]

As can be seen from Table 10, the superiority of the photoreceptor using an aromatic carboxylic acid, using an undercoat layer containing iodine, and using the titanyloxyphthalocyanine of the present invention as a charge generating material is apparent.
[0094]
【The invention's effect】
According to the present invention, amorphous titanyloxyphthalocyanine is dissolved in an aqueous solution in which an ionic substance is dissolved at a temperature of 50 ° C. or less (preferably 30 ° C. or less) under the presence of mechanical force (strain force, shear force, impact force, etc.). Then, a water-insoluble organic solvent was added to the system, and the titanyloxyphthalocyanine dispersed in the water system was transferred to a water-insoluble organic solvent system while removing water in the presence of mechanical force. Thereafter, by removing the water-insoluble organic solvent, an X-ray diffraction spectrum using CuKα as a radiation source has a Bragg angle (2θ ± 0.2 °) of 7.22 °, 9.60 °, 11.60 °, It has clear diffraction peaks at 13.40 °, 14.88 °, 18.34 °, 23.62 °, 24.14 °, and 27.32 °, and diffraction at the Bragg angle of 9.60 °. Peak is the largest diffraction peak Novel titanyloxyphthalocyanine with excellent dispersion stability, sufficient sensitivity to near-infrared light such as semiconductor laser light, and stable electric properties suitable for electrophotography Crystals are obtained. Further, the crystal lattice constants (error range ± 1%) are a = 16.308 °, b = 23.078 °, c = 8.7155 °, α = 101.352 °, β = 23.078 °, γ = 117. As described above, a novel titanyloxyphthalocyanine crystal excellent at 530 ° is obtained.
[0095]
By using such a novel titanyloxyphthalocyanine crystal as a charge generating material for the charge generating layer of the laminated photoreceptor, it has excellent electrical characteristics and sufficient sensitivity to near-infrared wavelength light such as semiconductor laser light. Thus, an image free of quality defects such as image noise and image density unevenness can be obtained, and a photoreceptor capable of maintaining stable electrical characteristics and image quality even in repeated use can be obtained.
Further, by using a hydrazone-based compound or a distyryl-based compound as the charge transporting material in the charge transporting layer of such a photoreceptor, a photoreceptor having more improved characteristics can be obtained.
[0096]
Further, a subbing layer provided between the conductive substrate and the photosensitive layer may be a cured film containing, as a main component, a melamine resin and either an aromatic carboxylic acid and / or an aromatic carboxylic anhydride and iodine fixed thereto. Alternatively, by forming a cured film containing, as a main component, a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylate and iodine fixed thereto, as a main component, a charge generation layer is formed on the cured film without unevenness. The coating can be formed with good adhesion, the variation in the electrical characteristics of the photoreceptor is further improved, image defects are further reduced, and the environmental dependence of the electrical characteristics of the photoreceptor is greatly improved.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction spectrum of the titanyloxyphthalocyanine crystal of the present invention.
FIG. 2 is an X-ray diffraction spectrum of type I titanyloxyphthalocyanine crystal (described in JP-A-62-67094).
FIG. 3 is an X-ray diffraction spectrum of an amorphous titanyloxyphthalocyanine crystal
FIG. 4 is an X-ray diffraction spectrum of α-type titanyloxyphthalocyanine crystal (described in JP-A-62-134651).
FIG. 5 is a light absorption spectrum of a titanyloxyphthalocyanine crystal, an I-type titanyloxyphthalocyanine crystal and an α-type titanyloxyphthalocyanine crystal of the present invention.
FIG. 6 is an X-ray diffraction spectrum of type II titanyloxyphthalocyanine crystal (described in JP-A-62-67094).
FIG. 7 is a schematic cross-sectional view of one embodiment of a photoreceptor according to the present invention.
[Explanation of symbols]
1 conductive substrate
2 Undercoat layer
3 Photosensitive layer
4 Charge generation layer
5 charge transport layer

Claims (13)

In the X-ray diffraction spectrum represented by the following general formula (I) and using CuKα as a radiation source, Bragg angles (2θ ± 0.2 °) 7.22 °, 9.60 °, 11.60 °, 13.40 °, 14.88 °, 18.34 °, 23.62 °, 24.14 °, and 27.32 °, and the diffraction peak at the Bragg angle of 9.60 ° is the maximum diffraction peak. And the crystal lattice constants (error range ± 1%) are: a = 16.3058 °, b = 23.078 °, c = 8.7155 °, α = 101.352 °, β = 23.078 °, γ = 117.530 °, titanyloxyphthalocyanine crystal.

[In the formula (I), X ¹ , X ² , X ³ and X ⁴ each represent either Cl or Br, and n, m, l and k each represent an integer of 0 to 4. ] Amorphous titanyloxyphthalocyanine is dispersed and atomized in an aqueous solution in which an ionic substance is dissolved at a temperature of 50 ° C. or less in the presence of mechanical force, and then a non-water-soluble organic solvent is added to the system, and the presence of mechanical force The titanyloxyphthalocyanine crystal according to claim 1, wherein the titanyloxyphthalocyanine crystal dispersed in an aqueous system is transferred to a water-insoluble organic solvent system while removing water, and then the water-insoluble organic solvent is removed. Recipe. 2. An electrophotographic photoreceptor comprising a photosensitive layer in which a charge generating layer and a charge transporting layer are dispersed and contained as a charge generating material on a conductive substrate, wherein the titanyl oxyphthalocyanine is contained in the electrophotographic photosensitive member according to claim 1. An electrophotographic photoreceptor comprising a titanyloxyphthalocyanine crystal. The electrophotographic photoreceptor according to claim 3, wherein the charge transport layer contains a hydrazone compound as a charge transport material. The electrophotographic photoreceptor according to claim 4, wherein the hydrazone-based compound is a compound represented by the following general formula (II).

[In the formula (II), R ¹ , R ² , R ³ and R ⁴ each represent an optionally substituted alkyl group, an aralkyl group, or an aryl group, and R ⁵ represents a hydrogen atom, a halogen atom, or an alkyl group. , An alkoxy group. Further, R ¹ and R ² may combine to form a ring, or one of R ¹ and R ² and R ⁵ may combine to form a ring. ] The electrophotographic photosensitive member according to claim 3, wherein the charge transport layer contains a distyryl compound as a charge transport material. 7. The electrophotographic photoreceptor according to claim 6, wherein the distyryl compound is a compound represented by the following general formula (III).

[In the formula (III), R ¹ , R ² , R ³ and R ⁴ each represent an optionally substituted aryl group or an alkyl group, and R ⁵ and R ⁶ represent a hydrogen atom, an alkyl group, an alkoxy group, respectively. And Ar represents any of an aryl group and an aromatic heterocyclic group which may be substituted. ] An undercoat layer is provided on a conductive substrate, and an electrophotographic photoreceptor comprising a photosensitive layer in which a charge generation layer and a charge transport layer each containing a titanyloxyphthalocyanine dispersed as a charge generation material are stacked thereon, The undercoat layer is a cured film containing, as a main component, a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylic acid anhydride and iodine fixed thereto, and the titanyloxyphthalocyanine crystal contained in the charge generation layer is An electrophotographic photosensitive member comprising the titanyloxyphthalocyanine crystal according to claim 1. An undercoat layer is provided on a conductive substrate, and an electrophotographic photoreceptor comprising a photosensitive layer in which a charge generation layer and a charge transport layer each containing a titanyloxyphthalocyanine dispersed as a charge generation material are stacked thereon, The undercoat layer is a cured film containing, as a main component, a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylate, and iodine fixed thereto, and the titanyloxyphthalocyanine crystal contained in the charge generation layer is claimed. Item 1. An electrophotographic photoreceptor comprising the titanyloxyphthalocyanine crystal according to item 1. 10. The electrophotographic photoconductor according to claim 8, wherein the charge transport layer contains a hydrazone compound as a charge transport material. The electrophotographic photoreceptor according to claim 10, wherein the hydrazone-based compound is a compound represented by the general formula (II). The electrophotographic photosensitive member according to claim 8, wherein the charge transport layer contains a distyryl compound as a charge transport material. The electrophotographic photosensitive member according to claim 12, wherein the distyryl compound is a compound represented by the general formula (III).

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