JP4036690B2 - Triarylamine compound having dialkylamino group - Google Patents

Description

（式中、Ｒ^１は、炭素数１〜４のアルキル基を表わし、同一でも異なっていてもよい。Ｒ^２は、水素原子、炭素数１〜４のアルキル基、もしくは置換もしくは無置換の芳香環基を表わし、Ｒ ^３ は、炭素数１〜４のアルキル基、もしくは置換もしくは無置換の芳香環基を表わす。ｎは１又は２の整数を表わす。Ａｒは置換もしくは無置換の芳香環基を表わす。）
【００１０】
【化４】

（式中、Ｒ^１は、炭素数１〜４のアルキル基を表わし、同一でも異なっていてもよい。Ｒ ^２は、水素原子、炭素数１〜４のアルキル基、もしくは置換もしくは無置換の芳香環基を表わす。Ａｒは置換もしくは無置換の芳香環基を表わす。）
【００１１】
この新規化合物を用いた感光体を繰り返し使用しても、画像品質を維持するのに有効である理由については、現時点では明らかになっていないが、構造内にＲ^１とＲ^２とで置換されたアミノ基（ジアルキルアミノ基）が含まれているために、このジアルキルアミノ基が、画像ボケの原因物質と考えられている酸化性ガスに対して有効な抑制効果を持っているものと考えられる。
また、この新規化合物を他の電荷輸送物質と併用して得られる感光体は、高感度でかつ繰り返し安定性等がさらに増加するものとなることも確認された。
【００１２】
なお、ジアルキルアミノ基を有する化合物として、特開昭６０−１９６７６８号公報および特許第２８８４３５３号公報等にスチルベン化合物が開示されている。しかしながら、これらは電荷輸送サイトであるトリアリールアミン構造の共鳴部位に強いメゾメリー効果（＋Ｍ効果）の置換基であるジアルキルアミノ基を有しているため、全体のイオン化ポテンシャル値は異常に小さくなる。
それ故、電荷輸送物質として単独使用した感光層の帯電保持能は、初期から、もしくは繰り返し使用により著しく悪くなるため、実用化は非常に難しいという致命的な欠点を有している。
また本発明の新規化合物のように他の電荷輸送物質と混合併用しても、該スチルベン化合物のイオン化ポテンシャル値が本発明の新規化合物のそれよりもかなり小さいので、スチルベン化合物自体が移動電荷のトラップサイトとなるために、感光体に使用しても感度が著しく低く、かつ残留電位が大きなものとなってしまう。
【００１３】
【発明の実施の形態】
本発明の前記一般式１で表される新規化合物である、ジアルキルアミノ基を有するトリアリールアミン化合物は、下記反応式に示すように、ニトロスチリル基置換トリアリールアミン化合物を水素還元し、ついでアルカリ存在下、アルキルハライド（Ｒ^１Ｘ）と反応させることにより容易に製造することができる。
また、本発明の前記一般式（２）で表わされる新規化合物である、少なくとも２つのジアルキルアミノ基を有するトリアリールアミン化合物も同様な反応により容易に製造することができる。
【００１４】
【化５】

【００１５】
一般式（１）および（２）に記載されるアルキル基の具体例としては、メチル基、エチル基、プロピル基、ブチル基などを挙げることができる。
同じく芳香環基としては、ベンゼン、ナフタレン、アントラセン、及びピレンなど芳香族炭化水素環の１価〜６価の芳香族炭化水素基、並びにピリジン、キノリン、チオフェン、フラン、オキサゾール、オキサジアゾール、カルバゾールなど芳香族複素環の１価〜６価の芳香族複素環基を挙げることができる。
また、これらの置換基としては、上記アルキル基の具体例で挙げたもの、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基などのアルコキシ基、またはフッ素原子、塩素原子、臭素原子、ヨウ素原子のハロゲン原子、及び芳香環基などを挙げることができる。
【００１６】
以下、一般式（１）の好ましい例を表１に、一般式（２）の好ましい例を表２に挙げる。但し、本発明は、これらの化合物に限定されるものではない。
【００１７】
【表１−１】

注）化合物Ｎｏ．１−４は参考例である。
【００１８】
【表１−２】

注）化合物Ｎｏ．１−８及びＮｏ．１−９は参考例である。
【００１９】
【表２】

注）化合物Ｎｏ．２−５及びＮｏ．２−６は参考例である。
【００２０】
前述したように、本発明の新規なトリアリールアミン化合物を用いた感光体は、それを搭載した電子写真画像形成装置によって、長期間繰り返し使用しても高耐久性を有し、かつ画像濃度低下あるいは画像ボケの発生による画像劣化を抑制でき、高画質画像が安定に得られる光導電性材料として極めて有用であるが、染顔料やルイス酸などの増感剤によって増感されるものである。
さらにこのトリアリールアミン化合物は、電荷発生物質として有機染顔料が用いられたいわゆる機能分離型有機感光体における電荷輸送物質としてとりわけ有用な物質である。
【００２１】
該機能分離型有機感光体において、本発明のトリアリールアミン化合物を電荷輸送物質として用いた場合、それと併用可能な電荷発生物質を例示する。
すなわち、シーアイピグメントブルー２５（カラーインデックスCI 21180）、シーアイピグメントレッド４１（CI 21200）、シーアイアシッドレッド５２（CI 45100）、シーアイベーシックレッド３（CI 45210）、カルバゾール骨格を有するアゾ顔料（特開昭５３−９５０３３号公報に記載）、ジスチリルベンゼン骨格を有するアゾ顔料（特開昭５３−１３３４４５号公報）、トリフェニルアミン骨格を有するアゾ顔料（特開昭５３−１３２３４７号公報に記載）、ジベンゾチオフェン骨格を有するアゾ顔料（特開昭５４−２１７２８号公報に記載）、オキサジアゾール骨格を有するアゾ顔料（特開昭５４−１２７４２号公報に記載）、フルオレノン骨格を有するアゾ顔料（特開昭５４−２２８３４号公報に記載）、ビススチルベン骨格を有するアゾ顔料（特開昭５４−１７７３３号公報に記載）、ジスチリルオキサジアゾール骨格を有するアゾ顔料（特開昭５４−２１２９号公報に記載）、ジスチリルカルバゾール骨格を有するアゾ顔料（特開昭５４−１４９６７号公報に記載）、ベンズアントロン骨格を有するアゾ顔料などのアゾ顔料。例えば、シーアイピグメントブルー１６（CI 74100）、Ｙ型オキソチタニウムフタロシアニン（特開昭６４−１７０６６号公報）、Ａ（β）型オキソチタニウムフタロシアニン、Ｂ（α）型オキソチタニウムフタロシアニン、Ｉ型オキソチタニウムフタロシアニン（特開平１１−２１４６６号公報に記載）、II型クロロガリウムフタロシアニン（飯島他、日本化学会第６７春季年回、1B4,04(1994））、Ｖ型ヒドロキシガリウムフタロシアニン（大門他、日本化学会第67春季年回、1B4,05(1994））、Ｘ型無金属フタロシアニン（米国特許第３，８１６，１１８号）などのフタロシアニン系顔料、シーアイバットブラウン５（CI 73410）、シーアイバットダイ（CI 73030）などのインジコ系顔料、アルゴスカーレットＢ（バイエル社製）、インタンスレンスカーレットＲ（バイエル社製）などのペリレン顔料などが挙げられる。なお、これらの材料は単独あるいは２種類以上が併用されても良い。
また、本発明のジアルキルアミノ基を有するトリアリールアミン化合物は他の電荷輸送材料と混合しても効果を損なうことはない。
【００２２】
【実施例】
次に、本発明の新規なトリアリールアミン化合物を合成した事実を示す実施例およびその合成した化合物を感光体の電荷輸送物質として用いて、その有用性を示す応用例と応用比較例によって、本発明をより詳細に説明する。
実施例１（化合物Ｎｏ．２−１の製造）
４，４’−ビス（４−アミノフェネチル）−４”メチルトリフェニルアミン３．９４ｇを脱水ＴＨＦ３０ｍｌに溶解させ、撹拌しながらこれに６０％水素化ナトリウム２．５３ｇを少量づつ加えた。ついでエチルヨージド７．４１ｇを加え、６０℃にて６時間加熱撹拌を行なった。反応終了後、水氷浴にて系内を冷却し、水２ｍｌを滴下した。これを酢酸エチルにて抽出し、水層が中性となるまで有機層の水洗を繰り返した。取り出した有機層を硫酸マグネシウムにて脱水し、減圧濃縮することにより薄黄色油状物を得た。ついでシリカゲルカラムクロマト処理［展開溶媒トルエン／酢酸エチル＝（３０／１）ｖｏｌ］して、無色油状物のジアルキルアミノ基を有するトリアリールアミン化合物（化合物Ｎｏ．２−１）を２．８０ｇ（収率５８．０％）得た。なお元素分析結果（％）は以下の通りであった。
行なった測値：Ｃ，８４．７４；Ｈ，８．７８；Ｎ，６．８１．計算値（Ｃ_４３Ｈ_５１Ｎ_３）：Ｃ，８４．６８；Ｈ，８．４３；Ｎ，６．８９．
このものの赤外線吸収スペクトル図を図１に示す。
【００２３】
実施例２、３（化合物Ｎｏ．１−１及び化合物Ｎｏ．２−３の製造例）
実施例１と同様な反応条件で他のジアルキルアミノ基を有するトリアリールアミン化合物を得た（化合物Ｎｏ．１−１、及び化合物Ｎｏ．２−３）。製造結果、並びに元素分析結果を表３に示す。また、赤外線吸収スペクトル図をそれぞれ図２及び図３に示す。
【００２４】
【表３】

【００２５】
応用例１
電荷発生物質として下記構造式で表わされるフルオレノン系ビスアゾ顔料２．５部を、ポリビニルブチラール樹脂１部／シクロヘキサノン８０部／メチルエチルケトン４０部の混合溶媒に加え、ボールミルにて粉砕混合した。得られた分散液をアルミ板上にドクターブレードで塗布し、自然乾燥して約０．５μｍの電荷発生層を形成した。
【００２６】
【化６】

次に、ポリカーボネート樹脂［（株）帝人製パンライトＴＳ−２０５０］１部とテトラヒドロフラン８部の樹脂溶液に、電荷輸送物質として実施例２で得られたジアルキルアミノ基を有するトリアリールアミン化合物（化合物Ｎｏ．１−１）１部を溶解し、この溶液を前記電荷輸送層上にドクターブレードで塗布し、乾燥して厚さ約２０μｍの電荷輸送層を形成し感光体（感光体Ｎｏ．１）を作成した。
【００２７】
次に、こうして得られた積層型電子写真感光体の特性を調べるため、この感光体に静電複写紙試験装置［（株）川口電機製作所製ＥＰＡ８１００型］を用いて暗所で−６ＫＶのコロナ放電を２０秒間行なって帯電させ、２０秒間暗所に放置した後、表面電位Ｖｏ（Ｖ）を測定した。ついで、６６０ｎｍ波長光を感光体表面での照度が１μＷ／ｃｍ^２になるように照射して、感光体表面電位が−８００（Ｖ）から−４００（Ｖ）になるまでの必要露光量Ｅ１／２（μＪ／ｃｍ^２）および３０秒間照射後の残留電位Ｖｒ（Ｖ）を測定したを測定した。結果を表４に示す。
【００２８】
応用例２
応用例１において、ジアルキルアミノ基を有するトリアリールアミン化合物Ｎｏ．１−１をＮｏ．２−３の化合物にした以外は、すべて応用例１と同様にして、感光体Ｎｏ．２を作製し、評価した。結果を表４に示す。
【００２９】
応用比較例１
応用例１において、ジアルキルアミノ基を有するトリアリールアミン化合物を下記のスチルベン化合物（特開昭６０−１９６７６８号公報に記載のもの）にした以外は、すべて応用例１と同様にして、感光体Ｎｏ．３を作製し、評価した。結果を表４に示す。
【００３０】
【化７】

【００３１】
応用比較例２
応用例１において、ジアルキルアミノ基を有するトリアリールアミン化合物を下記のテトラフェニルメタン化合物（特開２０００−２３１２０４号公報に記載のもの）にした以外は、すべて応用例１と同様にして、感光体Ｎｏ．４を作製し、評価した。結果を表４に示す。
【００３２】
【化８】

【００３３】
応用比較例３
応用例１において、ジアルキルアミノ基を有するトリアリールアミン化合物を下記のヒンダードアミン系酸化防止剤にした以外は、すべて応用例１と同様にして、感光体Ｎｏ．５を作製し、評価した。結果を表４に示す。
【００３４】
【化９】

【００３５】
【表４】

【００３６】
以上の評価結果から、本発明のジアルキルアミノ基を有するトリアリールアミン化合物である、新規化合物を含有する電子写真感光体はいずれも帯電保持能、残留電位、感度特性とも非常に優れており、実用に問題なく使用できることがわかる。
一方、応用比較例１の感光体Ｎｏ．３の帯電保持能は、著しく悪く、実用化は非常に難しいという致命的な欠点を有している。また、応用比較例２及び３の感光体Ｎｏ．４及び５の帯電保持能は良好なものの、いずれも感度測定ができず、電荷輸送能が非常に悪いものであることがわかる。
【００３７】
応用例３
アルミニウムシリンダー上に下記組成の下引き層塗工液、応用例２で用いた電荷発生層塗工液、および電荷輸送層塗工液を、浸漬塗工によって順次塗布、乾燥し、３．５μｍの下引き層、０．２μｍの電荷発生層、２３μｍの電荷輸送層を形成した（感光体Ｎｏ．６）。
【００３８】
◎下引き層塗工液
二酸化チタン粉末：４００部
メラミン樹脂：６５部
アルキッド樹脂：１２０部
メチルエチルケトン：４００部
【００３９】
以上のように作製した電子写真感光体を、電子写真プロセス用カートリッジに装着し、帯電方式をコロナ帯電方式（スコロトロン型）、画像露光光源を６５５ｎｍの半導体レーザー（ＬＤ）を用いたリコー製ｉｍａｇｉｏ ＭＦ２２００改造機にて暗部電位８００（−Ｖ）に設定した後、連続してトータル１０万枚印刷相当の繰り返し試験を行なった。その際、初期画像及び繰り返し試験後の画像について評価を行なった。また、初期及び繰り返し試験後の明部電位も測定した。結果を表５に示す。
【００４０】
応用比較例４
応用例３において、ジアルキルアミノ基を有するトリアリールアミン化合物を下記構造式で表されるトリアリールアミン化合物にした以外は、すべて応用例３と同様にして、感光体Ｎｏ．７を作製し、評価した。結果を表５に示す。
【００４１】
【化１０】

【００４２】
【表５】

【００４３】
以上の評価結果から、１０万枚印刷後においても明部電位上昇は少なく、本発明のジアルキルアミノ基を有するトリアリールアミン化合物を含有した電子写真感光体Ｎｏ．６は、高画質画像が安定に得られることが確認された。
一方、応用比較例４の感光体Ｎｏ．７は、１０万枚印刷後でも明部電位の上昇は小さいものの、本発明の化合物を含む感光体と比べ、繰り返し使用による解像度低下が非常に大きいことがわかる。
【００４４】
応用例４、応用比較例５
また、電子写真感光体Ｎｏ．６及びＮｏ．７について５０ｐｐｍの窒素酸化物（ＮＯｘ）ガス濃度に調整されたデシケータ中に４日間放置し、前後における画像評価を行なった。
【００４５】
【表６】

【００４６】
表６の評価結果より、感光体に本発明のアミン化合物を含有させることによって、酸化性ガスに対する耐性、すなわち解像度低下抑止が大幅に向上することがわかる。一方、感光体Ｎｏ．７は初期では画像品質は良好であるが、酸化性ガスにより著しい解像度の低下が起きることがわかる。
【００４７】
【発明の効果】
以上、詳細かつ具体的な記載より明らかなように、本発明によれば、一般式（１）、（２）で表わされるジアルキルアミノ基を有するトリアリールアミン化合物が新規化合物として得られた。
また、該化合物を光導電性材料として含有させた電子写真感光体によると、感度低下を招くことなく、繰り返し使用しおよび酸化性ガスなどに対する環境耐性が大幅に向上するため、高耐久性を有し、長期にわたって高解像度の画質が得られ、該化合物の有用性が確認された。
すなわち、本発明の新規化合物によって、高耐久化と高画質化の両立を可能とし、かつ高画質画像が長期に渡って安定に得られる電子写真感光体が実現され、及びそれを用いた電子写真方法、電子写真装置および電子写真装置用プロセスカートリッジを提供することができた。
【図面の簡単な説明】
【図１】本発明の化合物の赤外線吸収スペクトルを示した図である。
【図２】本発明の他の化合物の赤外線吸収スペクトルを示した図である。
【図３】本発明の更に他の化合物の赤外線吸収スペクトルを示した図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel triarylamine compound having a dialkylamino group particularly useful as an organic photoconductive material for an electrophotographic photoreceptor.
[0002]
[Prior art]
In recent years, there has been a remarkable development in information processing system machines using electrophotography. In particular, laser printers and digital copying machines that convert information into digital signals and record information using light have significantly improved print quality and reliability. Furthermore, they have been widely applied to laser printers or digital copiers capable of full-color printing by fusing with high-speed technology. From such a background, it is particularly important to achieve both high image quality and high durability as a required photoreceptor function.
[0003]
As photoconductors used in these electrophotographic laser printers, digital copiers, etc., those using organic photosensitive materials (OPC) are generally widely used for reasons such as cost, productivity and non-pollution. Applied. The layer structure of the OPC photoreceptor is roughly divided into a single layer type and a function separation type laminated structure. The first practical OPC, the PVK-TNF charge transfer complex type photoreceptor, was the former single layer type.
On the other hand, in 1968, Hayashi and Regensburger independently invented a PVK / a-Se laminated photoreceptor, and later called 1977 Melz et al. And 1978 Schlosser called an organic pigment dispersion layer and an organic low molecular weight dispersion polymer layer. A multi-layer photoconductor in which all photosensitive layers are made of organic materials has been announced.
These laminated photoreceptors are composed of a charge generation layer (CGL) that absorbs light to generate charges, and a charge transport layer (CTL) that injects and transports charges generated by CGL and neutralizes surface charges. Therefore, it is also called a function separation type laminated photoconductor.
The development of this layered photoreceptor has dramatically improved sensitivity and durability compared to single-layer photoreceptors. In addition, since materials having different functions, which are called charge generation materials (CGM) and charge transport materials (CTM), can be individually designed, the selection range of these materials has been greatly increased. For these reasons, the function-separated laminated photoconductor has the mainstream layer structure of the current OPC photoconductor.
The mechanism of electrostatic latent image formation in the function-separated type photoconductor is that when the photoconductor is charged and then irradiated with light, the light passes through the charge transport layer and is absorbed by the charge generation material in the charge generation layer to generate a charge. . The charges generated thereby are injected into the charge transport layer at the interface between the charge generation layer and the charge transport layer, and further moved through the charge transport layer by an electric field, thereby neutralizing the surface charge of the photoreceptor to form an electrostatic latent image. To form.
[0004]
However, organic photoconductors have large film scraping due to repeated use, and when the photosensitive layer film is scraped, the charged potential of the photoconductor decreases, the photosensitivity deteriorates, the soiling due to scratches on the photoconductor surface, image There is a strong tendency for density reduction or image quality degradation to be promoted. Therefore, the wear resistance of organic photoreceptors has been cited as a major issue. Further, in recent years, with the increase in the speed of an electrophotographic apparatus or the reduction in the diameter of the photoreceptor accompanying the downsizing of the apparatus, it has become a more important issue to improve the durability of the photoreceptor.
[0005]
As a method for improving the abrasion resistance of the photoconductor, a method of imparting lubricity to the photosensitive layer, curing it, adding a filler, or a low molecular charge transport material (CTM) molecular dispersion polymer layer can be used. Methods using polymer charge transport materials are widely known.
However, if the abrasion of the photosensitive layer is suppressed by these methods, a new problem occurs. That is, ozone, NOx, and other oxidizing substances that are repeatedly used on the surface of the photosensitive layer and adsorbed by the surrounding environment are adsorbed. Known to cause problems. Conventionally, the problem has been avoided to some extent by removing the blur generating material little by little together with the photosensitive layer.
However, as described above, in order to meet the recent demand for higher resolution and higher durability, a new method has to be provided. One method of reducing these effects is to mount a heater on the photoreceptor, which is a major obstacle to downsizing the apparatus and reducing power consumption. Additives such as antioxidants are also effective means, but mere additives are those that do not have photoconductivity. Therefore, addition of a large amount to the photosensitive layer can reduce the sensitivity and increase the residual potential. It will imitate the problem of photographic characteristics.
Further, for example, JP-A-2000-231204 discloses an aromatic compound having a dialkylamino group as an acid scavenger to a photoreceptor. This compound is effective for the image quality after repeated use, but has a low charge transport ability, so that it is difficult to meet the demand for high sensitivity and high speed, and the addition amount is limited.
[0006]
As described above, electrophotographic photoreceptors that have high wear resistance or have less shaving due to process design around the photoreceptor can avoid adverse effects on image quality such as image blurring and reduced resolution as side effects. Therefore, it has been difficult to achieve both high durability and high image quality. This is because a higher resistance is suitable for suppressing the occurrence of image blur, and a lower resistance is suitable for suppressing the increase in residual potential. It is difficult to solve.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide an electrophotographic photosensitive material that has high durability even for repeated use over a long period of time, suppresses image deterioration due to image density reduction or image blurring, and stably obtains high-quality images. It is an object of the present invention to provide a novel triarylamine compound having a dialkylamino group that is useful as a photoconductive material for a body.
[0008]
[Means to solve the problem]
The inventors of the present invention synthesized a triarylamine compound having a dialkylamino group represented by the following general formulas (1) and (2) as a new substance, and formed a photoconductor containing this substance as a photoconductive material. It was found that when mounted on a forming apparatus and an image is formed, an image flow (image blur) due to a blur generating substance such as an oxidizing gas does not occur, and it is useful for solving the above-mentioned problems.
[0009]
[Chemical 3]

(In the formula, R ¹ represents an alkyl group having 1 to 4 carbon atoms and may be the same or different. R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aromatic group. R ³ represents a cyclic group, R ³ represents an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aromatic ring group, n represents an integer of 1 or 2. Ar represents a substituted or unsubstituted aromatic ring group Represents.)
[0010]
[Formula 4]

(In the formula, R ¹ represents an alkyl group having 1 to 4 carbon atoms and may be the same or different. R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms , or a substituted or unsubstituted aromatic group. (Ar represents a substituted or unsubstituted aromatic ring group.)
[0011]
The reason why it is effective to maintain the image quality even when the photoconductor using the novel compound is used repeatedly is not clear at present, but the structure is substituted with R ¹ and R ^2. Therefore, it is considered that this dialkylamino group has an effective inhibitory effect on the oxidizing gas that is considered to be the cause of image blur. .
It has also been confirmed that a photoreceptor obtained by using this novel compound in combination with another charge transporting material has high sensitivity and further increases repeated stability and the like.
[0012]
As compounds having a dialkylamino group, stilbene compounds are disclosed in JP-A-60-196768 and Japanese Patent No. 2884353. However, since these have a dialkylamino group which is a substituent of a strong meso-merry effect (+ M effect) at the resonance site of the triarylamine structure which is a charge transport site, the overall ionization potential value becomes abnormally small.
Therefore, the charge retention ability of the photosensitive layer used alone as the charge transport material is remarkably deteriorated from the beginning or by repeated use, and thus has a fatal drawback that it is very difficult to put it to practical use.
Even when mixed with other charge transport materials such as the novel compound of the present invention, the ionization potential value of the stilbene compound is considerably smaller than that of the novel compound of the present invention. Since it becomes a site, even if it is used for a photoconductor, the sensitivity is extremely low and the residual potential is large.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The triarylamine compound having a dialkylamino group, which is a novel compound represented by the general formula 1 of the present invention, is obtained by reducing a nitrostyryl group-substituted triarylamine compound with hydrogen as shown in the following reaction formula. It can be easily produced by reacting with an alkyl halide (R ¹ X) in the presence.
In addition, a triarylamine compound having at least two dialkylamino groups, which is a novel compound represented by the general formula (2) of the present invention, can be easily produced by a similar reaction.
[0014]
[Chemical formula 5]

[0015]
Specific examples of the alkyl group described in the general formulas (1) and (2) include a methyl group, an ethyl group, a propyl group, and a butyl group.
Similarly, aromatic ring groups include monovalent to hexavalent aromatic hydrocarbon groups such as benzene, naphthalene, anthracene, and pyrene, and pyridine, quinoline, thiophene, furan, oxazole, oxadiazole, and carbazole. And monovalent to hexavalent aromatic heterocyclic groups of an aromatic heterocyclic ring.
These substituents include those exemplified in the above specific examples of alkyl groups, alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group, or halogen atoms of fluorine atom, chlorine atom, bromine atom and iodine atom. atoms, and Ru and the like can be illustrated aromatic ring group.
[0016]
Hereinafter, preferable examples of the general formula (1) are listed in Table 1, and preferable examples of the general formula (2) are listed in Table 2. However, the present invention is not limited to these compounds.
[0017]
[Table 1-1]

Note) Compound No. 1-4 is a reference example.
[0018]
[Table 1-2]

Note) Compound No. 1-8 and no . 1-9 is a reference example.
[0019]
[Table 2]

Note) Compound No. 2-5 and no . 2-6 is a reference example.
[0020]
As described above, the photoconductor using the novel triarylamine compound of the present invention has high durability even if it is repeatedly used for a long time by the electrophotographic image forming apparatus equipped with the photoconductor, and the image density is lowered. Alternatively, it is extremely useful as a photoconductive material that can suppress image deterioration due to occurrence of image blurring and stably obtain a high-quality image, but is sensitized by a sensitizer such as a dye or pigment or Lewis acid.
Furthermore, this triarylamine compound is a particularly useful substance as a charge transport substance in a so-called function-separated organic photoreceptor in which an organic dye / pigment is used as a charge generation substance.
[0021]
In the function-separated organic photoreceptor, when the triarylamine compound of the present invention is used as a charge transport material, charge generation materials that can be used in combination therewith are exemplified.
That is, C.I. Pigment Blue 25 (Color Index CI 21180), C.I. Pigment Red 41 (CI 21200), C.I. Acid Red 52 (CI 45100), C.I. Basic Red 3 (CI 45210), and an azo pigment having a carbazole skeleton 53-95033), azo pigments having a distyrylbenzene skeleton (JP-A-53-133445), azo pigments having a triphenylamine skeleton (described in JP-A-53-132347), dibenzo An azo pigment having a thiophene skeleton (described in JP-A No. 54-21728), an azo pigment having an oxadiazole skeleton (described in JP-A No. 54-12742), an azo pigment having a fluorenone skeleton (Japanese Unexamined Patent Publication No. 54-22834), an azo face having a bisstilbene skeleton (Described in JP-A No. 54-17733), azo pigments having a distyryl oxadiazole skeleton (described in JP-A No. 54-2129), azo pigments having a distyryl carbazole skeleton (Japanese Unexamined Patent Publication No. 54-129) 14967), and azo pigments such as azo pigments having a benzanthrone skeleton. For example, CI Pigment Blue 16 (CI 74100), Y-type oxotitanium phthalocyanine (Japanese Patent Laid-Open No. 64-17066), A (β) -type oxotitanium phthalocyanine, B (α) -type oxotitanium phthalocyanine, I-type oxotitanium phthalocyanine (Described in JP-A-11-21466), type II chlorogallium phthalocyanine (Iijima et al., Chemical Society of Japan, 67th Spring Annual, 1B4, 04 (1994)), type V hydroxygallium phthalocyanine (Damon et al., Chemical Society of Japan) 67th Spring Annual, 1B4,05 (1994)), phthalocyanine pigments such as X-type metal-free phthalocyanine (US Pat. No. 3,816,118), C-Ibat Brown 5 (CI 73410), C-Ibat Dye (CI 73030) and other indigo pigments, Argo Scarlet B (manufactured by Bayer), Insence Cale Such as perylene pigments such as theft R (manufactured by Bayer Co., Ltd.) and the like. These materials may be used alone or in combination of two or more.
The triarylamine compound having a dialkylamino group of the present invention does not impair the effect even when mixed with other charge transport materials.
[0022]
【Example】
Next, an example showing the fact that the novel triarylamine compound of the present invention was synthesized, and an application example and an application comparative example showing the usefulness of the synthesized compound as a charge transport material for a photoreceptor, The invention will be described in more detail.
Example 1 (Production of Compound No. 2-1)
4.94 g of 4,4′-bis (4-aminophenethyl) -4 ″ methyltriphenylamine was dissolved in 30 ml of dehydrated THF, and 2.53 g of 60% sodium hydride was added in small portions to this while stirring. 7.41 g was added and the mixture was heated and stirred for 6 hours at 60 ° C. After completion of the reaction, the system was cooled in a water ice bath, and 2 ml of water was added dropwise. The organic layer was washed repeatedly with water until it became neutral, and the extracted organic layer was dehydrated with magnesium sulfate and concentrated under reduced pressure to obtain a pale yellow oily substance, followed by silica gel column chromatography [developing solvent: toluene / acetic acid. Ethyl = (30/1) vol], and 2.80 g of a triarylamine compound (compound No. 2-1) having a dialkylamino group as a colorless oily substance (yield: 58). The elemental analysis results (%) were as follows.
Measurements taken: C, 84.74; H, 8.78; N, 6.81. Calculated (C ₄₃ H ₅₁ N ₃ ): C, 84.68; H, 8.43; N, 6.89.
The infrared absorption spectrum of this product is shown in FIG.
[0023]
Examples 2 and 3 (Production Examples of Compound No. 1-1 and Compound No. 2-3)
Triarylamine compounds having other dialkylamino groups were obtained under the same reaction conditions as in Example 1 (Compound No. 1-1 and Compound No. 2-3). Production results and elemental analysis results are shown in Table 3. Infrared absorption spectrum diagrams are shown in FIGS. 2 and 3, respectively.
[0024]
[Table 3]

[0025]
Application example 1
As a charge generation material, 2.5 parts of a fluorenone-based bisazo pigment represented by the following structural formula was added to a mixed solvent of 1 part of polyvinyl butyral resin / 80 parts of cyclohexanone / 40 parts of methyl ethyl ketone, and pulverized and mixed with a ball mill. The obtained dispersion was applied on an aluminum plate with a doctor blade and naturally dried to form a charge generation layer of about 0.5 μm.
[0026]
[Chemical 6]

Next, a triarylamine compound (compound) having a dialkylamino group obtained in Example 2 as a charge transport material in a resin solution of 1 part of a polycarbonate resin [Panlite TS-2050 manufactured by Teijin Ltd.] and 8 parts of tetrahydrofuran. No. 1-1) 1 part was dissolved, and this solution was applied onto the charge transport layer with a doctor blade and dried to form a charge transport layer having a thickness of about 20 μm to form a photoconductor (photoconductor No. 1). It was created.
[0027]
Next, in order to investigate the characteristics of the multilayer electrophotographic photosensitive member thus obtained, an electrostatic copying paper test apparatus [EPA8100 type manufactured by Kawaguchi Electric Manufacturing Co., Ltd.] was used for this photosensitive member in the dark. After discharging for 20 seconds and charging, and leaving it in a dark place for 20 seconds, the surface potential Vo (V) was measured. Next, irradiation with 660 nm wavelength light is performed so that the illuminance on the surface of the photoconductor is 1 μW / cm ² , and the necessary exposure amount E1 / E1 until the photoconductor surface potential becomes −800 (V) to −400 (V). 2 (μJ / cm ² ) and the residual potential Vr (V) after irradiation for 30 seconds were measured. The results are shown in Table 4.
[0028]
Application example 2
In Application Example 1, triarylamine compound No. 1 having a dialkylamino group was used. 1-1. Except for the compound of 2-3, the same procedure as in Application Example 1 was repeated for the photoreceptor No. 2 was prepared and evaluated. The results are shown in Table 4.
[0029]
Application comparison example 1
In Application Example 1, the same procedure as in Application Example 1 was conducted except that the triarylamine compound having a dialkylamino group was changed to the following stilbene compound (described in JP-A-60-196768). . 3 was made and evaluated. The results are shown in Table 4.
[0030]
[Chemical 7]

[0031]
Application comparison example 2
A photoconductor in Application Example 1 except that the triarylamine compound having a dialkylamino group was changed to the following tetraphenylmethane compound (described in JP-A-2000-231204). No. 4 was prepared and evaluated. The results are shown in Table 4.
[0032]
[Chemical 8]

[0033]
Application comparison example 3
In Application Example 1, the same procedure as in Application Example 1 was conducted except that the triarylamine compound having a dialkylamino group was changed to the following hindered amine antioxidant. 5 was prepared and evaluated. The results are shown in Table 4.
[0034]
[Chemical 9]

[0035]
[Table 4]

[0036]
From the above evaluation results, all of the electrophotographic photoreceptors containing the novel compounds, which are triarylamine compounds having a dialkylamino group of the present invention, are extremely excellent in charge retention ability, residual potential, and sensitivity characteristics. It can be seen that it can be used without problems.
On the other hand, the photoreceptor No. No. 3 has a fatal defect that the charge holding ability is extremely poor and practical application is very difficult. Further, the photosensitive member Nos. Although the charge holding ability of 4 and 5 is good, none of them can be measured for sensitivity, indicating that the charge transport ability is very poor.
[0037]
Application example 3
The undercoat layer coating solution having the following composition on the aluminum cylinder, the charge generation layer coating solution used in Application Example 2, and the charge transport layer coating solution were sequentially applied by dip coating and dried, and 3.5 μm in thickness. An undercoat layer, a 0.2 μm charge generation layer, and a 23 μm charge transport layer were formed (photoreceptor No. 6).
[0038]
◎ Undercoat layer coating solution Titanium dioxide powder: 400 parts Melamine resin: 65 parts Alkyd resin: 120 parts Methyl ethyl ketone: 400 parts
The electrophotographic photosensitive member produced as described above is mounted on an electrophotographic process cartridge, the charging method is a corona charging method (scorotron type), and the image exposure light source is a 655 nm semiconductor laser (LD) manufactured by Ricoh imgio MF2200. After setting the dark part potential to 800 (-V) with a remodeling machine, a repeated test equivalent to printing a total of 100,000 sheets was continuously performed. At that time, the initial image and the image after the repeated test were evaluated. Further, the bright part potential after the initial and repeated tests was also measured. The results are shown in Table 5.
[0040]
Application comparison example 4
In Application Example 3, the same procedure as in Application Example 3 was conducted except that the triarylamine compound having a dialkylamino group was changed to a triarylamine compound represented by the following structural formula. 7 was made and evaluated. The results are shown in Table 5.
[0041]
[Chemical Formula 10]

[0042]
[Table 5]

[0043]
From the above evaluation results, the bright portion potential increase was small even after printing 100,000 sheets, and the electrophotographic photosensitive member No. 1 containing the triarylamine compound having a dialkylamino group of the present invention was used. No. 6 confirmed that a high-quality image can be obtained stably.
On the other hand, the photoconductor No. 4 of Comparative Application Example 4 was used. 7 shows that although the increase in the bright portion potential is small even after printing 100,000 sheets, the resolution decrease due to repeated use is very large as compared with the photoreceptor containing the compound of the present invention.
[0044]
Application example 4, application comparison example 5
In addition, the electrophotographic photosensitive member No. 6 and no. No. 7 was left in a desiccator adjusted to a nitrogen oxide (NOx) gas concentration of 50 ppm for 4 days, and image evaluation was performed before and after.
[0045]
[Table 6]

[0046]
From the evaluation results in Table 6, it can be seen that the resistance to oxidizing gas, that is, the resolution reduction suppression is greatly improved by including the amine compound of the present invention in the photoreceptor. On the other hand, the photoreceptor No. 7 shows that the image quality is good at the initial stage, but the resolution is significantly reduced by the oxidizing gas.
[0047]
【The invention's effect】
As described above, as clear from the detailed and specific description, according to the present invention, a triarylamine compound having a dialkylamino group represented by the general formulas (1) and (2) was obtained as a novel compound.
In addition, according to the electrophotographic photosensitive member containing the compound as a photoconductive material, the durability against repeated use and environmental resistance against oxidizing gas is greatly improved without causing a decrease in sensitivity. However, high resolution image quality was obtained over a long period of time, confirming the usefulness of the compound.
That is, the novel compound of the present invention realizes an electrophotographic photoreceptor that can achieve both high durability and high image quality, and can stably obtain high-quality images over a long period of time, and electrophotography using the same. It was possible to provide a method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.
[Brief description of the drawings]
FIG. 1 is an infrared absorption spectrum of a compound of the present invention.
FIG. 2 is an infrared absorption spectrum of another compound of the present invention.
FIG. 3 is an infrared absorption spectrum of still another compound of the present invention.

Claims (2)

A triarylamine compound having at least one dialkylamino group represented by the following general formula (1):

(In the formula, R ¹ represents an alkyl group having 1 to 4 carbon atoms and may be the same or different. R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aromatic group. R ³ represents a cyclic group, R ³ represents an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aromatic ring group, n represents an integer of 1 or 2. Ar represents a substituted or unsubstituted aromatic ring group Represents.) A triarylamine compound having at least two dialkylamino groups represented by the following general formula (2):

(In the formula, R ¹ represents an alkyl group having 1 to 4 carbon atoms and may be the same or different. R ² represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aromatic group. (Ar represents a substituted or unsubstituted aromatic ring group.)

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