【発明の詳細な説明】[Detailed description of the invention]
（産業上の利用分野）
本発明は光導電性有機材料に関する。
（従来の技術）
近年、光導電性有機材料は電子写真に限らず、
レーザープリンター、LEDプリンター、イメー
ジセンサー等の感光材料としても広く使用される
ようになつて来ている。
これらの光導電性有機材料の１種としてペリレ
ン系色素を400〜600nmの波長の光に対して感度
を有する電荷発生物質として使用することが提案
されている。
（発明が解決しようとしている問題点）
従来提案されたペリレン系色素は、特に電子写
真の感光材料として使用した場合、帯電後の露光
による感度が低く、また通常のカールソンプロセ
スを順次繰返した場合には帯電電位が低下し、且
つ露光後の残留電位も徐々に上昇し、その結果画
像部の画像濃度が低く、その上白地のカブリが多
く、高い品質の画像を得ることができないという
問題があり、実用化されなかつた。
（問題点を解決するための手段）
本発明者は、上述の従来技術の問題点を解決す
べく鋭意研究の結果、特定の構造のペリレン系色
素の光導電性は、該ペリレン系色素の処理条件に
よつて大幅に移動し、特定の構造のペリレン系色
素を特定の結晶形態とし、且つ特定の範囲の粒子
径を有するように調製するときは、上記の従来技
術の問題点が解決され、十分に実用化し得る高い
性能を有する光導電性有機材料が得られることを
知見して本発明を完成した。
すなわち、本発明は、α変態の結晶形態を有
し、その平均粒子径が0.05〜0.1μmの範囲であり、
下記式で表わされることを特徴とする光導電性有
機材料である。
本発明を詳細に説明すると、本発明の光導電性
有機材料の化学構造自体は従来公知であり、従来
から優れた性能を有する高級有機顔料として公知
の物質（C.I.ピグメントレツド178）と同一構造
を有する。上記顔料は従来公知の方法で容易に合
成でき、また市場からも容易に入手し得るもので
ある。
これらの公知のペリレン系色素は２種の結晶形
態のもの、すなわち、α変態とβ変態のものが知
られており、α変態のものは４〜10μmの粒子径
を有するものが知られ、また、β変態のものは
0.01〜0.6μmの粒子径を有するものが知られてい
る。これらのいずれの結晶形態でも、いずれの粒
子径のものも有機顔料として高い性能を有してい
る。
しかしながらこれらの公知の結晶形態および粒
子径のペリレン系色素を用いて、例えば、電子写
真用の感光体を作成すべくバインダー樹脂と混合
するとその分散性が非常に劣り、また何らかの特
別の手段で分散性を十分としても電子写真用感光
体としては十分な性能を発揮するものではなかつ
た。
本発明者はこれらのペリレン系色素の結晶形態
および粒子径と感光材料としての関係を種々研究
の結果、これらのペリレン系色素の結晶形態をα
変態とし、且つ、その平均粒子径を0.05〜0.1μm、
好ましくは粒子の大部分を上記範囲内に入るよう
に粒子径をコントロールするときは、該ペリレン
系色素のバインダー樹脂中への分散性が良好とな
るとともに、これらを用いて得られた感光体の電
子写真用としての性能が大幅に向上することを知
見したものである。
本発明の光導電性有機材料は、従来公知のβ変
態のペリレン系色素を、一旦無定形とし、次いで
キシレン、Ｏ−ジクロロベンゼン、ニトロベンゼ
ン、ジメチルホルムアミド、Ｎ−メチル−２−ピ
ロリドン、ジメチルスルホキシド、メチルエチル
ケトン、シクロヘキサノン、ピリジン、キノリン
等の有機溶剤を用いて処理してα変態に変換する
とともに、その平均粒子径を0.05〜0.1μmの範囲
に入るように揃えることによつて得られる。
特に好ましい処理方法は、市販のβ変態のペリ
レン顔料を、例えば、濃硫酸の如き強力な溶剤に
溶解し、次いで例えば水の如き非溶剤中に析出さ
せて、その結晶形態を一旦無定形とし、次いで上
記の如き有機溶剤中で、約10〜50℃の温度で、約
１〜10時間処理する方法であり、このような方法
によつて、無定形のペリレン系色素をα変態に変
え、且つその平均粒子径を0.05〜0.1μmの範囲に
入るように揃えることができる。
（作用・効果）
以上の如き本発明の光導電性有機材料を、バイ
ンダー樹脂中に分散させて電子写真用の感光体と
し、従来の上記と同一構造のペリレン系色素を使
用した電子写真用の感光体と比較すると、著しく
優れた感度を有し、且つカールソンプロセスの繰
返し特性が非常に優れ、多数回の繰返し使用によ
つても、その電子写真特性の低下がみられない電
子写真用感光体を与えるものである。
次に実施例を挙げて本発明を具体的に説明す
る。なお、文中、部または％とあるのは重量基準
である。
実施例 １
下記式で表わされる市販のPigment Red178
（BASF社製、パリオゲンレツドＫ 3911HD、
β変態、粒子径0.01〜0.6μm）
（以下原料顔料という）10部を濃硫酸100部中に
外部冷却しながら溶解し、次に氷水中に徐々に注
入して原料顔料を無定形状に析出させ、水洗、乾
燥後200部のＮ−メチル−２−ピロリドン中に加
え、室温で約５時間処理を行つて粒子径0.05〜
0.1μmの本発明の光導電性有機材料を得た。
この光導電性有機材料について下記の条件でＸ
線回折を行つたところ、第４図に示す如く回折角
度（2θ）約10°〜11°，14°〜15°および23°〜24°
の範
囲内にそれぞれ特徴的な回折ピークを示した。
Ｘ線回折条件は下記の通りである。
Target＝Cu，Scan Speed＝１（２／min）
Filetr＝Ni，Chart Speed＝10mm／min
Voltage＝25KV，Angle Range＝４〜30（2θ）
Current＝15mA，Div.Slit＝1n
Full Scale＝4000C.P.S.，Scat.Slit＝1n
Time Const.＝2sec，Rec.Slit＝0.2mm
測定装置は日本電子株式会社製DXタイプＸ線
回折装置である。
尚比較のために上記の原料顔料を上記と同一条
件でＸ線回折を行つたところ、添付図面の第５図
に示す如く回折角度（2θ）約13°〜14°，19°〜20°
，
22°〜23°，24°および28°〜29°等に特徴的な回折ピ
ークを示し、本発明の光導電性有機材料とは全く
異なる結晶性質（β変態）を有することが明らか
となつた。
更に、参考のために本発明の光導電性有機材料
（第１図）と、該光導電性有機材料と同一の構造
式を有する原料顔料（第２図）の電子顕微鏡写真
を示す。
評価例 １
以下の処方にて感光液を作成した。
ポリビニルカルバゾール（ツビコール210）
100部
実施例１の光導電性有機材料 ５部
ポリエステル樹脂（バイロン200） 10部
２，５−ジクロロ−ｐ−ベンゾキノン ５部
混合溶媒（トルエン／THF＝８／２）
1500部
上記混合物をアルミナ製ボールミルに入れ、５
時間分散後100μmのアルミニウム板にワイヤーバ
ーにて塗布し、乾燥後の膜厚が15μmになる様に
塗布、乾燥して感光体１を得た。
参考例
実施例で使用した原料顔料を用いて評価例１と
同様にして感光体２を得た。
測定例 １
川口電機製作所製エレクトロスタテイツクペー
パーアナライザーSP428を用いて電子写真特性を
測定した。
測定条件
測定モード スタテイツクNo.１
印加電圧 ＋6.0KV
露光強度（面照度）
25Lux（タングステンランプ2856°K）
結 果
初期帯電電位（Voボルト）
感光体１ 感光体２
＋620 ＋590
暗中10秒後の電位保持率（％）
感光体１ 感光体２
94 83
半減衰露光（Ｅ1/2Lux.sec）
感光体１ 感光体２
4.0 10.0
以上の結果から暗減衰特性および感度ともに本
発明の光導電性有機材料を使用した例の方が著し
く優れていることがわかる。
測定例 ２
感光体１および２について、1000サイクルの繰
返し特性の測定を行い、第３図の結果を得た。
感光体２の帯電電位の変化は大きく変化してい
るが、感光体１の帯電電位は初期のものと殆ど変
化せず良好であり、本発明の光導電性材料の顕著
な効果を示している。
(Industrial Application Field) The present invention relates to photoconductive organic materials. (Prior art) In recent years, photoconductive organic materials have been used not only for electrophotography, but also for electrophotography.
It is also becoming widely used as a photosensitive material for laser printers, LED printers, image sensors, etc. As one of these photoconductive organic materials, it has been proposed to use a perylene dye as a charge generating substance sensitive to light with a wavelength of 400 to 600 nm. (Problems to be Solved by the Invention) Perylene dyes that have been proposed so far have low sensitivity due to exposure after charging, especially when used as photosensitive materials for electrophotography, and when the normal Carlson process is repeated sequentially. The charging potential decreases and the residual potential after exposure gradually increases, resulting in low image density in the image area, and moreover, there is a lot of fog on the white background, making it impossible to obtain high quality images. , it was not put into practical use. (Means for Solving the Problems) As a result of intensive research to solve the problems of the above-mentioned prior art, the present inventors found that the photoconductivity of a perylene dye with a specific structure is determined by the treatment of the perylene dye. When a perylene dye that moves significantly depending on conditions and has a specific structure is prepared to have a specific crystal form and a particle size in a specific range, the above problems of the prior art are solved, The present invention was completed based on the finding that a photoconductive organic material having high performance that can be put to practical use can be obtained. That is, the present invention has an α-modified crystal form and has an average particle size in the range of 0.05 to 0.1 μm,
It is a photoconductive organic material characterized by being represented by the following formula. To explain the present invention in detail, the chemical structure of the photoconductive organic material of the present invention itself is conventionally known, and has the same structure as that of a substance (CI Pigment Red 178) that has been conventionally known as a high-grade organic pigment with excellent performance. has. The above pigments can be easily synthesized by conventionally known methods and are also easily available on the market. These known perylene dyes are known to have two types of crystal forms, namely α-modification and β-modification, and the α-modification is known to have a particle size of 4 to 10 μm. , the β metamorphosis is
Those having a particle size of 0.01 to 0.6 μm are known. Any of these crystal forms and particle sizes have high performance as organic pigments. However, when these perylene dyes with known crystal forms and particle sizes are mixed with a binder resin to create photoreceptors for electrophotography, their dispersibility is very poor, and it is difficult to disperse them using some special means. Even if it had sufficient properties, it did not exhibit sufficient performance as an electrophotographic photoreceptor. As a result of various studies on the relationship between the crystal form and particle size of these perylene dyes and their use as light-sensitive materials, the present inventor has determined that the crystal form of these perylene dyes is α
transformation, and the average particle size is 0.05 to 0.1 μm.
Preferably, when controlling the particle diameter so that most of the particles fall within the above range, the dispersibility of the perylene dye in the binder resin will be good, and the photoreceptor obtained using the perylene dye will have good dispersibility. It was discovered that the performance for electrophotography is significantly improved. In the photoconductive organic material of the present invention, a conventionally known β-modified perylene dye is made amorphous, and then xylene, O-dichlorobenzene, nitrobenzene, dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, etc. It can be obtained by treating with an organic solvent such as methyl ethyl ketone, cyclohexanone, pyridine, or quinoline to convert it to α modification, and adjusting the average particle size to fall within the range of 0.05 to 0.1 μm. A particularly preferred treatment method is to dissolve a commercially available β-modified perylene pigment in a strong solvent such as concentrated sulfuric acid, and then precipitate it in a non-solvent such as water to temporarily render the crystalline form amorphous. This method is then treated in an organic solvent as described above at a temperature of about 10 to 50°C for about 1 to 10 hours, and by such a method, the amorphous perylene dye is converted to the α modification, and The average particle size can be adjusted to fall within the range of 0.05 to 0.1 μm. (Function/Effect) The photoconductive organic material of the present invention as described above is dispersed in a binder resin to form a photoreceptor for electrophotography, and a photoconductor for electrophotography using a conventional perylene dye having the same structure as the above. An electrophotographic photoreceptor that has significantly superior sensitivity when compared to photoreceptors, has excellent Carlson process repeatability, and shows no deterioration in its electrophotographic characteristics even after repeated use many times. It gives Next, the present invention will be specifically explained with reference to Examples. Note that parts and percentages in the text are based on weight. Example 1 Commercially available Pigment Red178 represented by the following formula
(Manufactured by BASF, Paliogen Red K 3911HD,
β-transformation, particle size 0.01-0.6μm) (hereinafter referred to as the raw pigment) was dissolved in 100 parts of concentrated sulfuric acid while externally cooling, and then gradually poured into ice water to precipitate the raw pigment into an amorphous shape. After washing with water and drying, 200 parts of N -Add to methyl-2-pyrrolidone and treat at room temperature for about 5 hours to obtain particles with a particle size of 0.05~
A 0.1 μm photoconductive organic material of the present invention was obtained. For this photoconductive organic material, X
When line diffraction was performed, the diffraction angles (2θ) were approximately 10° to 11°, 14° to 15°, and 23° to 24°, as shown in Figure 4.
Each showed a characteristic diffraction peak within the range of . The X-ray diffraction conditions are as follows. Target=Cu, Scan Speed=1 (2/min) Filetr=Ni, Chart Speed=10mm/min Voltage=25KV, Angle Range=4~30 (2θ) Current=15mA, Div.Slit=1n Full Scale=4000C. PS, Scat.Slit=1n Time Const.=2sec, Rec.Slit=0.2mm The measuring device is a DX type X-ray diffraction device manufactured by JEOL Ltd. For comparison, the above raw pigment was subjected to X-ray diffraction under the same conditions as above, and as shown in Figure 5 of the attached drawings, the diffraction angles (2θ) were approximately 13° to 14°, 19° to 20°.
，
It was revealed that the photoconductive organic material exhibited characteristic diffraction peaks at 22° to 23°, 24°, and 28° to 29°, and had crystal properties (β transformation) that were completely different from those of the photoconductive organic material of the present invention. . Furthermore, for reference, electron micrographs of the photoconductive organic material of the present invention (FIG. 1) and a raw material pigment having the same structural formula as the photoconductive organic material (FIG. 2) are shown. Evaluation Example 1 A photosensitive solution was prepared using the following formulation. Polyvinylcarbazole (Tubicol 210)
100 parts Photoconductive organic material of Example 1 5 parts Polyester resin (Vylon 200) 10 parts 2,5-dichloro-p-benzoquinone 5 parts Mixed solvent (toluene/THF=8/2)
1500 parts Put the above mixture into an alumina ball mill,
After time dispersion, it was coated on a 100 μm aluminum plate using a wire bar, coated so that the film thickness after drying was 15 μm, and dried to obtain photoreceptor 1. Reference Example A photoreceptor 2 was obtained in the same manner as in Evaluation Example 1 using the raw pigment used in the Example. Measurement Example 1 Electrophotographic characteristics were measured using Electrostatic Paper Analyzer SP428 manufactured by Kawaguchi Electric Seisakusho. Measurement conditions Measurement mode Statute No. 1 Applied voltage +6.0KV Exposure intensity (surface illuminance)
25Lux (tungsten lamp 2856°K) Results Initial charging potential (Vo volts) Photoconductor 1 Photoconductor 2 +620 +590 Potential retention rate after 10 seconds in the dark (%) Photoconductor 1 Photoconductor 2 94 83 Half-attenuation exposure (E1/ 2Lux.sec) Photoreceptor 1 Photoreceptor 2 4.0 10.0 From the above results, it can be seen that the example using the photoconductive organic material of the present invention is significantly superior in both dark decay characteristics and sensitivity. Measurement Example 2 The repeat characteristics of Photoreceptors 1 and 2 were measured for 1000 cycles, and the results shown in FIG. 3 were obtained. Although the charging potential of photoreceptor 2 has changed significantly, the charging potential of photoreceptor 1 has hardly changed from the initial one and is good, indicating the remarkable effect of the photoconductive material of the present invention. .
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は本発明の光導電性有機材料（実施例
１）の粒子構造を示す電子顕微鏡写真（倍率３万
倍）を、第２図は該光導電性有機材料と同一の構
造式を有する原料顔料の粒子構造を示す電子顕微
鏡写真（倍率３万倍）を示し、第３図は、本発明
の光導電性有機材料を用いた感光体と原料顔料を
用いた比較例の感光体の繰返し特性の測定結果を
示し、第４図は本発明の光導電性有機材料のＸ線
回折図を、第５図は原料顔料のＸ線回折図を示
す。
Figure 1 is an electron micrograph (30,000 times magnification) showing the particle structure of the photoconductive organic material of the present invention (Example 1), and Figure 2 has the same structural formula as the photoconductive organic material. An electron micrograph (30,000x magnification) showing the particle structure of the raw pigment is shown, and Figure 3 shows the repetition of a photoconductor using the photoconductive organic material of the present invention and a comparative example photoconductor using the raw pigment. The measurement results of the characteristics are shown, and FIG. 4 shows the X-ray diffraction pattern of the photoconductive organic material of the present invention, and FIG. 5 shows the X-ray diffraction pattern of the raw pigment.