JP3781362B2 - Electrophotographic photoreceptor - Google Patents

Description

（式（Ｉ）中、Ｒ¹、Ｒ²およびＲ⁴は夫々同一であっても異なっていてもよく、水素原子、置換基を有してもよい炭素数１〜８のアルキル基または置換基を有してもよいフェニル基を表し、Ｒ³はハロゲン原子または置換基を有してもよい炭素数１〜８のアルキル基を表し、ｎは０〜３の整数を表し、ｎが２以上の場合の２個以上あるＲ³は同一であっても異なっていてもよい）で示される化合物の少なくとも一種を含有することを特徴とするものである。
【００１１】
【発明の実施の形態】
前記一般式（Ｉ）で示される化合物の具体例を、下記構造式（Ｉ−１）〜（Ｉ−８）にて示す。
【００１２】

【００１３】
前記一般式（Ｉ）の化合物は、通常の方法により合成することができる。例えば、前記構造式（Ｉ−１）で示される化合物は、下記構造式（ＩＩ）で示される化合物を、適当な酸化剤（例えば、過マンガン酸カリウムなど）を用いて有機溶媒（例えば、クロロホルムなど）中で酸化することにより、容易に合成することができる。

【００１４】
以下、本発明の感光体の好適例の具体的構成について、図面を参照しながら説明する。
図１および図２は、感光体の各種構成例を示す摸式的断面図である。図中の符号１は導電性基体、２および５は感光層、３は電荷発生層、４は電荷輸送層、６は被覆層を夫々表す。
【００１５】
図１は、いわゆる単層型感光体の一構成例を示しており、導電性基体１上に、電荷発生物質と電荷輸送物質とを樹脂バインダ（結着材）中に分散した単層の感光層２が設けられ、必要に応じて被覆層（保護層）６が積層されてなる。図１に示す感光体は、電荷発生物質を電荷輸送物質および樹脂バインダを溶解した溶液中に分散せしめ、この分散液を導電性基体上に塗布することによって作製できる。さらに、必要な場合は被覆層を塗布形成することができる。
【００１６】
図２は、いわゆる積層型感光体の一構成例を示しており、導電性基体１上に、電荷発生物質を主体とする電荷発生層３と、電荷輸送物質を含有する電荷輸送層４とが順次積層された感光層５が設けられてなる。図２に示す感光体は、導電性基体上に電荷発生物質を真空蒸着するか、あるいは電荷発生物質の粒子を溶剤または樹脂バインダ中に分散して得た分散液を塗布、乾燥し、その上に電荷輸送物質および樹脂バインダを溶解した溶液を塗布、乾燥することにより作製することができる。
【００１７】
また、図示はしていないが、いずれのタイプの感光体においても、導電性基体と感光層との間に下引き層を設けることができる。下引き層は、導電性基体から感光層への不要な電荷の注入防止や、基体表面上の欠陥被覆、感光層の接着性の向上等の目的で必要に応じて設けることができ、樹脂を主成分とする層やアルマイト等の酸化被膜等からなる。
【００１８】
本発明の感光体においては、上記いずれのタイプの場合でも、感光層中に、電荷輸送物質として、前記一般式（Ｉ）で示される電子輸送性化合物の少なくとも一種を含有する。
以下、本発明の好適な実施の形態を図２に示す積層型感光体について説明するが、本発明は以下の具体例に限定されるものではない。
【００１９】
導電性基体１は，感光体の電極としての役目と同時に他の各層の支持体となっており、円筒状、板状、フィルム状のいずれでもよく、材質的にはアルミニウム、ステンレス鋼、ニッケルなどの金属、あるいはガラス、樹脂などの上に導電処理を施したものを用いることができる。
【００２０】
電荷発生層３は、前記したように電荷発生物質の粒子を樹脂バインダ中に分散させた材料を塗布するか、あるいは真空蒸着などの方法により形成され、光を受容して電荷を発生する。また、その電荷発生効率が高いことと同時に発生した電荷の電荷輸送層４への注入性が重要であり、電場依存性が少なく低電場でも注入のよいことが望ましい。
【００２１】
電荷発生物質としては、無金属フタロシアニン、チタニルフタロシアニンなどのフタロシアニン化合物、各種アゾ、キノン、インジゴ、シアニン、スクアリリウム、アズレニウム、ピリリウム化合物などの顔料あるいは染料や、セレンまたはセレン化合物などが用いられ、画像形成に使用する露光光源の光波長領域に応じて好適な物質を選ぶことができる。
【００２２】
電荷発生層は電荷発生機能を有すればよいので、その膜厚は電荷発生物質の光吸収係数より決まり、一般的には５μｍ以下であり、好適には２μｍ以下である。また、電荷発生層は、電荷発生物質を主体としてこれに電荷輸送物質などを添加して使用することも可能である。
【００２３】
電荷発生層用の樹脂バインダとしては、ポリカーボネート、ポリエステル、ポリアミド、ポリウレタン、塩化ビニル、フェノキシ樹脂、ポリビニルブチラール、ジアリルフタレート樹脂、メタクリル酸エステルの重合体および共重合体などを適宜組合せて使用することができる。
【００２４】
電荷輸送層４は、樹脂バインダ中に電荷輸送物質を分散させた塗膜であり、暗所では絶縁体層として感光体の電荷を保持し、光受容時には電荷発生層から注入される電荷を輸送する機能を発揮する。本発明においては、電荷輸送層中に、かかる電荷輸送物質として、前記一般式（Ｉ）で示される化合物の少なくとも一種を含有させることが必要であるが、他の電荷輸送物質を含有させることも可能である。本発明に係る電子輸送性化合物の好適添加量は、電荷輸送層４中に含まれる材料全体に対して、好適には１０〜６０重量％であり、より好適には１５〜５０重量％である。
【００２５】
電荷輸送層用の樹脂バインダとしては、ポリカーボネート、ポリエステル、ポリスチレン、メタクリル酸エステルの重合体および共重合体等を用いることができる。また、電荷輸送層中には、感光体を使用する際に使用上障害となるオゾン劣化などを防止する目的で、アミン系、フェノール系、硫黄系、亜リン酸エステル系、リン系などの酸化防止剤を含有させることも可能である。
【００２６】
図１に示す被覆層６は、暗所ではコロナ放電の電荷を受容して保持する機能を有しており、かつ、感光層が感応する光を透過する性能を有し、露光時に光を透過して感光層に到達させ、発生した電荷の注入を受けて表面電荷を中和消滅させることが必要である。被覆層の材料としては、ポリエステル、ポリアミドなどの有機絶縁性皮膜形成材料を使用することができる。また、これら有機材料とガラス樹脂、ＳｉＯ₂などの無機材料、さらには金属、金属酸化物などの電気抵抗を低減せしめる材料とを混合して用いることも可能である。被覆層の材料は、前述したように、電荷発生物質の光の吸収極大の波長領域においてできるだけ透明であることが望ましい。
【００２７】
被覆層自体の膜厚は、被覆層の配合組成にも依存するが、繰り返し連続使用したとき残留電位が増大するなどの悪影響が出ない範囲で任意に設定することができる。
【００２８】
なお、図１に示す単層型感光体の場合においても、前記一般式（Ｉ）で示される本発明に係る電子輸送性化合物の少なくとも一種を感光層２中に含有させることが必要であるが、その他の材料等は、上述の積層型感光体に用いたのと同様のものを用いることができ、特に制限されるものではない。好適には、電荷輸送物質として、前記一般式（Ｉ）の電子輸送性化合物とともに、正孔輸送物質を含有させる。かかる正孔輸送物質としては、ベンジジン誘導体やトリフェニルアミン誘導体などが好ましい。また、この場合の好適添加量は、感光層形成塗膜中に含まれる材料全体に対して、電子輸送性化合物については好適には１０〜６０重量％、より好適には１５〜５０重量％であり、正孔輸送物質は好適には１０〜６０重量％、より好適には２０〜５０重量％である。
【００２９】
【実施例】
以下、本発明を実施例により具体的に説明する。
実施例１
ｘ型無金属フタロシアニン（Ｈ₂Ｐｃ）２０重量部と、前記構造式（Ｉ−１）で示される化合物１００重量部とを、ポリエステル樹脂（商品名：バイロン２００、東洋紡績（株）製）１００重量部およびテトラヒドロフラン（ＴＨＦ）溶剤とともに３時間混合機により混練して塗布液を調製し、導電性基体としての外径３０ｍｍ、長さ２６０ｍｍのアルミニウム製ドラム上に、乾燥後の膜厚が１２μｍになるように塗布して、感光体を作製した。
【００３０】
実施例２
ｘ型無金属フタロシアニン（Ｈ₂Ｐｃ）２重量部と、前記構造式（Ｉ−２）で示される化合物４０重量部と、下記構造式、

で示されるベンジジン誘導体６０重量部と、ポリカーボネート樹脂（商品名：ＰＣＺ−２００、三菱ガス化学（株）製）１００重量部とを、塩化メチレンとともに３時間混合機により混練して塗布液を調製し、実施例１と同様のアルミニウム基体上に、乾燥後の膜厚が２０μｍになるように塗布して、感光体を作製した。
【００３１】
実施例３
チタニルフタロシアニン（ＴｉＯＰｃ）２重量部と、前記構造式（Ｉ−３）で示される化合物４０重量部と、下記構造式、

で示されるベンジジン誘導体６０重量部と、ポリカーボネート樹脂（商品名：ＢＰ−ＰＣ、出光興産（株）製）１００重量部とを、塩化メチレンとともに３時間混合機により混練して塗布液を調製し、実施例１と同様のアルミニウム基体上に、乾燥後の膜厚が２０μｍになるように塗布して、感光体を作製した。
【００３２】
実施例４
実施例３において、チタニルフタロシアニンに代えて下記構造式、

で示されるスクアリリウム化合物を用い、また、前記構造式（Ｉ−３）で示される化合物に代えて前記構造式（Ｉ−４）で示される化合物を用いた以外は実施例３と同様にして、感光体を作製した。
【００３３】
実施例５
チタニルフタロシアニン（ＴｉＯＰｃ）７０重量部と、塩化ビニル共重合体（商品名：ＭＲ−１１０、日本ゼオン（株）製）３０重量部とを、塩化メチレンとともに３時間混合機により混練して塗布液を調製し、実施例１と同様のアルミニウム基体上に、乾燥後の膜厚が１μｍになるように塗布して、電荷発生層を形成した。次に、前記構造式（Ｉ−５）で示される化合物１００重量部と、ポリカーボネート樹脂（商品名：ＰＣＺ−２００、三菱ガス化学（株）製）１００重量部と、シリコーンオイル０．１重量部とを塩化メチレンにて混合し、この電荷発生層上に乾燥後の膜厚が１０μｍとなるように塗布して電荷輸送層を形成し、感光体を作製した。
【００３４】
実施例６
実施例５において、チタニルフタロシアニンに代えて、下記構造式、

で示されるビスアゾ顔料を用いた以外は実施例５と同様にして、電荷発生層を形成した。次に、前記構造式（Ｉ−１）で示される化合物１００重量部と、ポリカーボネート樹脂（商品名：ＢＰ−ＰＣ、出光興産（株）製）１００重量部と、シリコーンオイル０．１重量部とを塩化メチレンにて混合し、この電荷発生層上に乾燥後の膜厚が１０μｍとなるように塗布して電荷輸送層を形成し、感光体を作製した。
【００３５】
実施例７
実施例５において、電荷発生物質として下記構造式、

で示されるビスアゾ顔料を用いた以外は実施例５と同様にして、電荷発生層を形成した。次に、前記構造式（Ｉ−２）で示される化合物１００重量部と、ポリカーボネート樹脂（商品名：ＢＰ−ＰＣ、出光興産（株）製）１００重量部と、シリコーンオイル０．１重量部とを、塩化メチレンにて混合し、この電荷発生層上に乾燥後の膜厚が１０μｍとなるように塗布して電荷輸送層を形成し、感光体を作製した。
【００３６】
このようにして得られた感光体の電子写真特性を以下のようにして評価した。暗所で＋４．５ｋＶのコロナ放電を行って感光体表面を正帯電せしめたときの初期の表面電位をＶｓ（Ｖ）とし、続いてコロナ放電を中止した状態で５秒間暗所保持したときの表面電位Ｖｄ（Ｖ）を測定し、さらに続いて感光体表面に照度１００ルックスの白色光を照射してＶｄが半分になるまでの時間（秒）を求め、感度Ｅ_1/2（ｌｕｘ・ｓ）とした。また、照度１００ルックスの白色光を１０秒間照射したときの表面電位を残留電位Ｖｒ（Ｖ）とした。さらに、実施例１〜５の感光体については、長波長光での高感度が期待できるため、波長７８０ｎｍの単色光を用いたときの電子写真特性も同時に測定した。すなわち、Ｖｄまでは上記と同様に測定し、次に、白色光の代わりに１μＷの単色光（７８０ｎｍ）を照射して半減衰露光量（μＪ／ｃｍ²）を求め、また、この光を１０秒間感光体表面に照射したときの残留電位Ｖｒ（Ｖ）を測定した。この測定結果を下記の表１中に示す。
【００３７】
【表１】

【００３８】
【発明の効果】
以上説明してきたように、本発明によれば、導電性基体上に設けた感光層中に、電子輸送性を有する電荷輸送物質として、前記一般式（Ｉ）で示される化合物を用いたことにより、正帯電において高感度で電気特性に優れた感光体を得ることが可能となった。また、電荷発生物質としては露光光源の種類に応じて好適な物質を選ぶことができ、フタロシアニン化合物、スクアリリウム化合物、ビスアゾ化合物などを用いることにより、半導体レーザプリンターや複写機等に使用可能な感光体を得ることができる。さらに、必要に応じて表面に被覆層を設けて耐久性を向上することが可能である。
【図面の簡単な説明】
【図１】本発明の一例の単層型電子写真用感光体を示す摸式的断面図である。
【図２】本発明の他の例の積層型電子写真用感光体を示す摸式的断面図である。
【符号の説明】
１ 導電性基体
２ 感光層（単層）
３ 電荷発生層
４ 電荷輸送層
５ 感光体（積層）
６ 被覆層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoreceptor for electrophotography (hereinafter, also simply referred to as “photoreceptor”), and more specifically, to an electrophotography containing a specific compound in a photoconductive layer (photosensitive layer) formed on a conductive substrate. The present invention relates to a photoreceptor.
[0002]
[Prior art]
Conventionally, as a photosensitive layer of an electrophotographic photoreceptor, an inorganic photoconductive material such as selenium or a selenium alloy or an inorganic photoconductive material such as zinc oxide or cadmium sulfide dispersed in a resin binder is used. Has been. In recent years, research on electrophotographic photoreceptors using organic photoconductive materials has progressed, and sensitivity and durability have been improved and put into practical use.
[0003]
In addition, the photosensitive member needs to have a function of holding a surface charge in the dark, a function of receiving light to generate a charge, and a function of receiving light and transporting a charge. In addition, a so-called single-layer type photoconductor that combines these functions and a layer that separates the functions into a layer that mainly contributes to charge generation and a layer that contributes to the retention of surface charge in the dark and the charge transport during photoreception. And so-called laminated type photoreceptors.
[0004]
For example, the Carlson method is applied to image formation by electrophotography using these photoreceptors. In this method, the image is formed by charging the photoconductor in the dark by corona discharge, forming an electrostatic latent image such as text or a picture of an original on the charged photoconductor surface, and forming a static image. The electrostatic latent image was developed by toner and the developed toner image was fixed on a support such as paper. The photoconductor after the toner image was transferred was subjected to charge removal, residual toner removal, and light charge removal. Later, it is used again.
[0005]
Organic photoreceptors in practical use have advantages such as flexibility, film formability, low cost, and safety compared to inorganic photoreceptors, and due to the variety of materials, further improvements in sensitivity and durability are possible. It is being advanced. Most of the organic photoreceptors are multi-layer photoreceptors in which functions are separated into a charge generation layer and a charge transport layer. In general, in a multilayer organic photoreceptor, a charge generation layer made of a charge generation material such as a pigment or a dye and a charge transport layer made of a charge transport material such as hydrazone or triphenylamine are sequentially formed on a conductive substrate. In view of the nature of the electron-donating charge transport material, it is a hole transfer type and has sensitivity when the surface of the photoreceptor is negatively charged. However, with negative charging, corona discharge used during charging is more unstable than with positive charging, and ozone and nitrogen oxides are generated and easily adsorbed on the surface of the photoreceptor to cause physical and chemical degradation. There is a problem of deteriorating the environment. From this point of view, the positively charged type photoconductor having a greater degree of freedom of use conditions than the negatively charged photoconductor has a wider application range and is advantageous.
[0006]
Therefore, various photoreceptors for use with positive charging have been proposed. For example, a method in which a charge generation material and a charge transport material are simultaneously dispersed in a resin binder and used as a single photosensitive layer has been proposed and partially put into practical use. However, the sensitivity is not sufficient for application to a high-speed machine, and further improvement is required from the viewpoint of repetition characteristics. In order to achieve a function-separated layered structure for the purpose of increasing sensitivity, a method of forming a photoconductor by laminating a charge generation layer on a charge transport layer and using it in positive charge can be considered. However, in this method, since the charge generation layer is formed on the surface, there is a problem in stability during repeated use due to corona discharge, light irradiation, mechanical wear, and the like. On the other hand, it has also been proposed to further provide a protective layer on the charge generation layer. In this case, although mechanical wear is improved, there are problems such as a reduction in sensitivity and other electrical characteristics.
[0007]
Furthermore, a method of forming a photoconductor by laminating an electron transporting charge transport layer on a charge generation layer has also been proposed. As an electron transporting material, for example, B, 2,4,7-trinitro-9-fluorenone and the like are known, but this substance has carcinogenicity and has a safety problem. In addition, cyano compounds and quinone compounds have been proposed by JP-A-50-131941, JP-A-6-59483, JP-A-6-123986, JP-A-9-190003, and the like. In fact, no compound having a sufficient electron transport ability has been obtained.
[0008]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to solve the above-mentioned problems and use a new organic material that has not been used as an electron transporting charge transport material for the photosensitive layer so that it can be used for highly sensitive copying machines and printers. An object of the present invention is to provide a positively charged electrophotographic photoreceptor.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors diligently studied various materials, and as a result of conducting many experiments, although the technical clarification has not yet been made sufficiently, the following general formula ( The use of the specific compound represented by I) as a charge transporting material having an electron transporting property is extremely effective in improving electrophotographic characteristics, and thus a high-sensitivity photoconductor usable with positive charging can be obtained. As a result, the present invention has been completed.
[0010]
That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a photosensitive layer containing a charge generating substance and a charge transporting substance is provided on a conductive substrate, and the photosensitive layer is represented by the following general formula (I),

(In the formula (I), R ¹ , R ² and R ⁴ may be the same or different, and each may have a hydrogen atom or a C 1-8 alkyl group or substituent which may have a substituent. R ³ represents a halogen atom or an optionally substituted alkyl group having 1 to 8 carbon atoms, n represents an integer of 0 to 3, and n is 2 or more In this case, two or more R ^{3 s} may be the same or different) and contain at least one compound represented by
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Specific examples of the compound represented by the general formula (I) are shown by the following structural formulas (I-1) to (I-8).
[0012]

[0013]
The compound of the general formula (I) can be synthesized by a usual method. For example, the compound represented by the structural formula (I-1) is obtained by converting the compound represented by the following structural formula (II) into an organic solvent (for example, chloroform using an appropriate oxidizing agent (for example, potassium permanganate)). Etc.) can be easily synthesized.

[0014]
Hereinafter, a specific configuration of a preferred example of the photoreceptor of the present invention will be described with reference to the drawings.
1 and 2 are schematic cross-sectional views showing various configuration examples of the photoreceptor. In the figure, reference numeral 1 is a conductive substrate, 2 and 5 are photosensitive layers, 3 is a charge generation layer, 4 is a charge transport layer, and 6 is a coating layer.
[0015]
FIG. 1 shows an example of the structure of a so-called single-layer type photosensitive member. A single-layer photosensitive member in which a charge generating substance and a charge transporting substance are dispersed in a resin binder (binder) on a conductive substrate 1. The layer 2 is provided, and a coating layer (protective layer) 6 is laminated as necessary. The photoreceptor shown in FIG. 1 can be produced by dispersing a charge generating substance in a solution in which a charge transporting substance and a resin binder are dissolved, and applying the dispersion onto a conductive substrate. Further, if necessary, a coating layer can be formed by coating.
[0016]
FIG. 2 shows an example of the structure of a so-called multilayer photoreceptor, in which a charge generation layer 3 mainly composed of a charge generation material and a charge transport layer 4 containing a charge transport material are formed on a conductive substrate 1. The photosensitive layer 5 laminated | stacked one by one is provided. The photoreceptor shown in FIG. 2 is obtained by vacuum-depositing a charge generation material on a conductive substrate, or applying and drying a dispersion obtained by dispersing charge generation material particles in a solvent or resin binder. It can be produced by applying and drying a solution in which a charge transport material and a resin binder are dissolved.
[0017]
Although not shown, an undercoat layer can be provided between the conductive substrate and the photosensitive layer in any type of photoreceptor. The undercoat layer can be provided as necessary for the purpose of preventing unnecessary charge injection from the conductive substrate to the photosensitive layer, covering defects on the substrate surface, improving the adhesion of the photosensitive layer, etc. It consists of a main component layer, an oxide film such as alumite, and the like.
[0018]
In the photoreceptor of the present invention, in any of the above types, the photosensitive layer contains at least one electron transporting compound represented by the general formula (I) as a charge transporting substance.
Hereinafter, a preferred embodiment of the present invention will be described with respect to a multilayer photoreceptor shown in FIG. 2, but the present invention is not limited to the following specific examples.
[0019]
The conductive substrate 1 serves as a support for each of the other layers as well as serving as an electrode of the photoreceptor, and may be any of a cylindrical shape, a plate shape, and a film shape, and is made of aluminum, stainless steel, nickel, etc. A metal or a material obtained by conducting a conductive treatment on glass, resin, or the like can be used.
[0020]
As described above, the charge generation layer 3 is formed by applying a material in which particles of a charge generation material are dispersed in a resin binder, or by a method such as vacuum deposition, and receives light to generate charges. In addition, since the charge generation efficiency is high, the injection property of the generated charge into the charge transport layer 4 is important, and it is desirable that the injection is good even in a low electric field with little electric field dependency.
[0021]
As the charge generation material, phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, pigments or dyes such as various azo, quinone, indigo, cyanine, squarylium, azurenium and pyrylium compounds, selenium or selenium compounds, etc. are used for image formation. A suitable substance can be selected according to the light wavelength region of the exposure light source used for the above.
[0022]
Since the charge generation layer only needs to have a charge generation function, the thickness thereof is determined by the light absorption coefficient of the charge generation material, and is generally 5 μm or less, and preferably 2 μm or less. In addition, the charge generation layer can be used mainly including a charge generation material with a charge transport material added thereto.
[0023]
As the resin binder for the charge generation layer, polycarbonate, polyester, polyamide, polyurethane, vinyl chloride, phenoxy resin, polyvinyl butyral, diallyl phthalate resin, methacrylic ester polymer and copolymer may be used in appropriate combination. it can.
[0024]
The charge transport layer 4 is a coating film in which a charge transport material is dispersed in a resin binder. The charge transport layer 4 retains the charge of the photoreceptor as an insulator layer in the dark, and transports the charge injected from the charge generation layer when receiving light. Demonstrate the function to do. In the present invention, the charge transport layer needs to contain at least one compound represented by the general formula (I) as the charge transport material, but may contain other charge transport materials. Is possible. A preferable addition amount of the electron transporting compound according to the present invention is preferably 10 to 60% by weight, and more preferably 15 to 50% by weight, with respect to the entire material contained in the charge transporting layer 4. .
[0025]
As the resin binder for the charge transport layer, polycarbonate, polyester, polystyrene, methacrylic ester polymers and copolymers, and the like can be used. In the charge transport layer, oxidation of amines, phenols, sulfurs, phosphites, phosphoruss, etc. is performed for the purpose of preventing ozone deterioration, which is a hindrance to the use of photoreceptors. It is also possible to contain an inhibitor.
[0026]
The coating layer 6 shown in FIG. 1 has a function of receiving and holding the electric charge of corona discharge in a dark place, and has a capability of transmitting light sensitive to the photosensitive layer, and transmits light during exposure. Thus, it is necessary to reach the photosensitive layer and neutralize and extinguish the surface charge upon receiving the generated charge injection. As a material for the coating layer, an organic insulating film forming material such as polyester or polyamide can be used. Further, it is also possible to use a mixture of these organic materials and inorganic materials such as glass resin and SiO ₂ and further materials that reduce electrical resistance such as metals and metal oxides. As described above, it is desirable that the material of the coating layer be as transparent as possible in the wavelength range of the light absorption maximum of the charge generation material.
[0027]
The film thickness of the coating layer itself depends on the blend composition of the coating layer, but can be arbitrarily set within a range where no adverse effect such as an increase in residual potential occurs when it is repeatedly used continuously.
[0028]
Even in the case of the single layer type photoreceptor shown in FIG. 1, it is necessary that the photosensitive layer 2 contains at least one kind of the electron transporting compound according to the present invention represented by the general formula (I). The other materials can be the same as those used for the above-mentioned laminated photoreceptor, and are not particularly limited. Preferably, a hole transport material is contained as the charge transport material together with the electron transport compound of the general formula (I). As such a hole transport material, a benzidine derivative, a triphenylamine derivative, or the like is preferable. Further, the preferred addition amount in this case is preferably 10 to 60% by weight, more preferably 15 to 50% by weight for the electron transporting compound with respect to the entire material contained in the photosensitive layer forming coating film. The hole transport material is preferably 10 to 60% by weight, more preferably 20 to 50% by weight.
[0029]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
Example 1
20 parts by weight of x-type metal-free phthalocyanine (H ₂ Pc) and 100 parts by weight of the compound represented by the structural formula (I-1) are mixed with a polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) 100 A coating solution is prepared by kneading with a mixer for 3 hours together with parts by weight and a tetrahydrofuran (THF) solvent, and the film thickness after drying is 12 μm on an aluminum drum having an outer diameter of 30 mm and a length of 260 mm as a conductive substrate. The photosensitive member was prepared by coating as described above.
[0030]
Example 2
2 parts by weight of x-type metal-free phthalocyanine (H ₂ Pc), 40 parts by weight of the compound represented by the structural formula (I-2),

A coating solution was prepared by kneading 60 parts by weight of a benzidine derivative represented by the above and 100 parts by weight of a polycarbonate resin (trade name: PCZ-200, manufactured by Mitsubishi Gas Chemical Co., Ltd.) with a methylene chloride for 3 hours. On the same aluminum substrate as in Example 1, it was applied so that the film thickness after drying was 20 μm, to prepare a photoreceptor.
[0031]
Example 3
2 parts by weight of titanyl phthalocyanine (TiOPc), 40 parts by weight of the compound represented by the structural formula (I-3), the following structural formula,

60 parts by weight of a benzidine derivative represented by the above and 100 parts by weight of a polycarbonate resin (trade name: BP-PC, manufactured by Idemitsu Kosan Co., Ltd.) are kneaded with a methylene chloride for 3 hours to prepare a coating solution, On the same aluminum substrate as in Example 1, it was applied so that the film thickness after drying was 20 μm, to prepare a photoreceptor.
[0032]
Example 4
In Example 3, instead of titanyl phthalocyanine, the following structural formula:

In the same manner as in Example 3, except that the squarylium compound represented by the formula (I-3) was used, and the compound represented by the structural formula (I-4) was used instead of the compound represented by the structural formula (I-3). A photoconductor was prepared.
[0033]
Example 5
70 parts by weight of titanyl phthalocyanine (TiOPc) and 30 parts by weight of a vinyl chloride copolymer (trade name: MR-110, manufactured by Nippon Zeon Co., Ltd.) are kneaded together with methylene chloride for 3 hours using a mixer to obtain a coating solution. The charge generation layer was formed by applying and coating on the same aluminum substrate as in Example 1 so that the film thickness after drying was 1 μm. Next, 100 parts by weight of the compound represented by the structural formula (I-5), 100 parts by weight of a polycarbonate resin (trade name: PCZ-200, manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 0.1 parts by weight of silicone oil Were mixed with methylene chloride, and applied to the charge generation layer so that the film thickness after drying was 10 μm to form a charge transport layer, thereby preparing a photoreceptor.
[0034]
Example 6
In Example 5, instead of titanyl phthalocyanine, the following structural formula:

A charge generation layer was formed in the same manner as in Example 5 except that the bisazo pigment represented by Next, 100 parts by weight of the compound represented by the structural formula (I-1), 100 parts by weight of a polycarbonate resin (trade name: BP-PC, manufactured by Idemitsu Kosan Co., Ltd.), 0.1 part by weight of silicone oil, Were mixed with methylene chloride and applied on the charge generation layer so that the film thickness after drying was 10 μm to form a charge transport layer, thereby preparing a photoreceptor.
[0035]
Example 7
In Example 5, the following structural formula is shown as the charge generating substance:

A charge generation layer was formed in the same manner as in Example 5 except that the bisazo pigment represented by Next, 100 parts by weight of the compound represented by the structural formula (I-2), 100 parts by weight of a polycarbonate resin (trade name: BP-PC, manufactured by Idemitsu Kosan Co., Ltd.), 0.1 part by weight of silicone oil, Were mixed with methylene chloride and applied on the charge generation layer so that the film thickness after drying was 10 μm to form a charge transport layer, thereby preparing a photoreceptor.
[0036]
The electrophotographic characteristics of the photoreceptor thus obtained were evaluated as follows. When the surface potential of the photosensitive member is positively charged by performing +4.5 kV corona discharge in a dark place, the initial surface potential is set to Vs (V). Subsequently, the corona discharge is stopped and kept in the dark place for 5 seconds. The surface potential Vd (V) is measured, and then the time (seconds) until Vd is halved by irradiating the photoreceptor surface with white light having an illuminance of 100 lux is obtained, and the sensitivity E _1/2 (lux · s ). The surface potential when irradiated with white light having an illuminance of 100 lux for 10 seconds was defined as a residual potential Vr (V). Furthermore, since the photoconductors of Examples 1 to 5 can be expected to have high sensitivity with long wavelength light, the electrophotographic characteristics when using monochromatic light with a wavelength of 780 nm were also measured at the same time. That is, the measurement is performed up to Vd in the same manner as described above. Next, 1 μW of monochromatic light (780 nm) is irradiated instead of white light to obtain a half-attenuated exposure (μJ / cm ² ). Residual potential Vr (V) was measured when the photosensitive member surface was irradiated for 2 seconds. The measurement results are shown in Table 1 below.
[0037]
[Table 1]

[0038]
【The invention's effect】
As described above, according to the present invention, the compound represented by the general formula (I) is used as the charge transport material having electron transport properties in the photosensitive layer provided on the conductive substrate. Thus, it has become possible to obtain a photoconductor with high sensitivity and excellent electrical characteristics in positive charging. As the charge generation material, a suitable material can be selected according to the type of exposure light source. By using a phthalocyanine compound, a squarylium compound, a bisazo compound, etc., a photoconductor that can be used in a semiconductor laser printer, a copying machine, etc. Can be obtained. Furthermore, if necessary, it is possible to improve the durability by providing a coating layer on the surface.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a single-layer electrophotographic photoreceptor according to an example of the present invention.
FIG. 2 is a schematic cross-sectional view showing a laminated electrophotographic photoreceptor according to another example of the present invention.
[Explanation of symbols]
1 Conductive substrate 2 Photosensitive layer (single layer)
3 Charge Generation Layer 4 Charge Transport Layer 5 Photoconductor (Lamination)
6 Coating layer

Claims (1)

In the electrophotographic photoreceptor in which a photosensitive layer containing a charge generation material and a charge transport material is provided on a conductive substrate, the photosensitive layer has the following general formula (I),

(In the formula (I), R ¹ , R ² and R ⁴ may be the same or different, and each may have a hydrogen atom or a C 1-8 alkyl group or substituent which may have a substituent. R ³ represents a halogen atom or an optionally substituted alkyl group having 1 to 8 carbon atoms, n represents an integer of 0 to 3, and n is 2 or more And R ^{3 in} the case of two or more may be the same or different).

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