JP2517893B2 - Electrophotographic photoreceptor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor having an organic pigment as a photoconductor, and more particularly to an electrophotographic photoreceptor having a polymer compound.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photoreceptor, an inorganic photoconductive substance such as amorphous selenium, selenium alloy, cadmium sulfide, zinc oxide, etc., and an organic photoconductive substance represented by polyvinylcarbazole and its derivatives have been used. Natural substances are widely known. The organic photoconductive substance has an advantage that it is superior in transparency, film-forming property, flexibility, and manufacturability to the inorganic photoconductive substance. Furthermore, in recent years, electrophotographic photoreceptors containing various perylene pigments in the photosensitive layer have also been proposed (for example, JP-A Nos. 57-176046 and 57-57).
176047, and Japanese Patent Laid-Open No. 2-37356). In these electrophotographic photoreceptors, when a photosensitive layer containing a perylene pigment is formed on a conductive substrate, a coating solution obtained by dissolving a binder resin such as polycarbonate, polyester or other and a perylene pigment in a solvent. Is applied by a coating method such as a dip coating method, and then the solvent is removed by drying.

[0003]

However, the electrophotographic photosensitive member using the conventionally proposed perylene pigment is
The photosensitivity is not sufficient, and when it is repeatedly used for a long period of time, there are problems that the charging property is lowered and the residual potential is increased, so that it cannot be satisfactorily used as an electrophotographic photoreceptor. The present invention has been made in view of the above problems in the conventional technique. According to the study by the present inventors, it has been clarified that these problems are caused by the following factors. (1) Since the photosensitive layer originally contains a binder resin having no photoconductivity, the movement of charges is hindered. (2) Impurities contained in the solvent and binder resin, especially chlorides and metal elements, remain in the photosensitive layer, and when used repeatedly, these impurities act as top centers, and perylene pigments and conductive materials. It causes an electrochemical reaction with the substrate. Therefore, an object of the present invention is to eliminate the above-mentioned factors in the case of using a perylene pigment and to provide an electrophotographic photosensitive member having high sensitivity and high durability.

[0004]

The present inventors achieve the above object by forming a photosensitive layer composed of a polymer compound having a perylene skeleton in the main chain by a vacuum vapor deposition polymerization method. After finding out that, the present invention has been completed. The present invention provides an electrophotographic photoreceptor comprising a photoconductive layer containing an organic photoconductive substance as a main component on a conductive substrate, wherein the charge generating material of the photoconductive layer is represented by the following formula (I). It is characterized in that it is composed of a polymer compound having in its main chain a plurality of perylene skeletons composed of repeating structural units .

[0005]

The above-mentioned polymer compound in the present invention is formed into a vapor-deposited film by a vacuum vapor deposition polymerization method using a perylene tetracarboxylic acid anhydride represented by the following formula (II) and an aromatic diamine compound represented by the following formula (III). It can be formed into a form, and its degree of polymerization is in the range of 10 to 50.

[0007] H ₂ N—R—NH ₂ (III) (In the formula, R has the same meaning as described above.)

In order to obtain satisfactory photosensitivity and excellent repetitive stability in the electrophotographic photoreceptor, the photosensitive layer preferably has the following. (1) To efficiently generate charge carriers. (2) The generated charge carriers are efficiently transported. (3) No electrochemical reaction occurs at the photosensitive layer and its interface during repeated use (especially in a high humidity environment). The electrophotographic photosensitive member of the present invention has excellent photosensitivity and has stable chargeability and sensitivity during repeated use.
The reason is considered as follows. (A) The polymer compound having a perylene skeleton in its main chain, which is used in the present invention, essentially has one or two phenyl nuclei alternately connecting the skeleton of a perylene pigment, which is a charge generating material having an electron transporting property. It has a simple structure, and it is easy for charges to move within the molecule. (B) By adopting the vacuum evaporation polymerization method, a photosensitive layer containing no binder resin, which originally has no photoconductivity, is formed. (C) By adopting the vacuum vapor deposition polymerization method, the photosensitive layer is formed without mixing harmful impurities such as chlorides and metal elements due to its photo-conductivity, especially its repeated stability.

In the electrophotographic photosensitive member of the present invention, as the conductive support, a metal plate made of aluminum, nickel, chromium, stainless steel or the like, a metal drum, or a metal foil, and a thin film of a metal or other conductive substance are used. The provided plastic film, paper coated with or impregnated with a conductivity-imparting agent, or a plastic film is used.

The photoconductive layer may have a single-layer structure or a laminated structure in which the charge-generating layer and the charge-transporting layer are functionally separated. In the case of a laminated structure, either the charge generation layer or the charge transport layer may be on the conductive support side. In the present invention, the charge generation layer or the photoconductive layer in the case of a single layer structure is composed of a polymer compound containing a plurality of perylene skeletons composed of the repeating structural unit represented by the above formula (I) in the main chain. To be done.
This layer can be formed by a vacuum vapor deposition polymerization method using a perylene tetracarboxylic acid anhydride represented by the following formula (II) and an aromatic diamine compound represented by the following formula (III).

[0011] H ₂ N—R—NH ₂ (III) (In the formula, R has the same meaning as described above.)

FIG. 1 is a schematic diagram of a vacuum vapor deposition polymerization apparatus used in the vacuum vapor deposition polymerization method of the present invention. In the figure, reference numeral 1 denotes a vacuum chamber in which evaporation containers 3 and 4 which can be heated by evaporation heaters 5 and 6, respectively, are mounted, and evaporation sources A and B are put therein. Shutters 7 and 8 are provided above the evaporation containers 3 and 4, respectively. A substrate 2 that can be heated by a substrate heating heater 9 is arranged above the evaporation source, and a conductive support is mounted on the substrate 2. The lower part of the vacuum chamber 1 is connected to a vacuum exhaust device 11 via a high vacuum valve 10. Further, nitrogen gas can be introduced into the vacuum chamber 1 from the nitrogen cylinder 13 through the gas introduction valve 14. In addition, 1
2 is a film thickness monitor.

The perylene tetracarboxylic acid anhydride represented by the above formula (II) is provided on one side of the evaporation vessel and the above formula (II) on the other side.
After the aromatic diamine compound represented by I) is put in as a vapor deposition source and the inside of the vacuum chamber 1 is depressurized to a predetermined pressure, each of the vaporization sources is heated to a predetermined temperature, and the conductive material placed on the substrate 2 is electrically conductive. Deposition on a transparent support. Then, an inert gas such as nitrogen is introduced into the vacuum chamber, and the conductive support is heated to a predetermined temperature to complete the polymerization of the substance forming the vapor deposition film.

The conditions for vacuum deposition are as follows: degree of vacuum: 10 ^-4
-10 ^-7 Torr, conductive support temperature: room temperature to 100
C., preferably in the range of room temperature to 50.degree. The heating temperature of the conductive support during polymerization is 150
A range of ˜350 ° C. is suitable. The film thickness of the vapor deposition film is 0.
The thickness is set to 01 to 5 μm, preferably 0.1 to 1 μm. When the film thickness is less than 0.01 μm, the photosensitivity is lowered, and when it is thicker than 5 μm, the dark decay is increased and the charging property is lowered. Therefore, the above range should be set. preferable.

The charge transport layer comprises a charge transport material and a binder resin. Examples of the charge transport material include the following.

(Pyrazolines)

(Hydrazones)

[0018]

[0019]

(Oxazoles)

(Oxadiazoles)

(Arylalkanes)

(Triphenyllyamines)

(Aryl-substituted ethylenes)

[0025]

[0026]

(Benzidines)

[0028]

[0029]

[0030]

[0031]

[0032]

(Bicarbazyl)

[0034]

Since these compounds have no film-forming property by themselves, they are used in combination with a binder resin having a good film-forming property. Examples of the binder resin used include polycarbonate, polyacrylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylic acid ester, styrene-methacrylic acid ester copolymer and the like. . The thickness of the charge transport layer is usually set to about 5 to 50 μm.

[0036]

The present invention will be described in more detail with reference to the following examples. Example 1 A photosensitive layer was formed using the vacuum vapor deposition polymerization apparatus of FIG. That is, 2 parts by weight of perylene tetracarboxylic acid anhydride represented by the following formula (1) and p-phenylenediamine represented by the formula (2) are used as evaporation sources A and B, and placed in the evaporation containers 3 and 4, respectively. An aluminum sheet was mounted on the substrate 2, and the vacuum chamber was evacuated to 10 ⁻⁶ Torr by a vacuum exhaust device. The substrate 2 was heated to 60 ° C. by the heater 9 for heating the substrate, and the evaporation sources A and B were heated to 350 ° C. and 150 ° C. by the heaters 5 and 6 for vapor deposition, respectively. After the vapor deposition source reached a predetermined temperature, the shutters 7 and 8 were opened to start vapor deposition. When the film thickness became 1 μm by the film thickness monitor, the shutters 7 and 8 were closed and heating by the vapor deposition heater was stopped. The gas introduction valve 14 is opened and nitrogen gas is supplied to about 0.
After gradually introducing it to 5, the vapor deposition film was heated to 250 ° C. by a substrate heating heater and held for 1 hour to form a polymer compound composed of a monomer unit represented by the following formula (3). A charge generation layer having a film thickness of 0.5 μm was formed.

[0037]

N, N'- is formed on the formed charge generation layer.
Diphenyl-N, N-bis (3-methylphenyl)-
1 part by weight of [1,1-biphenyl] -4,4′-diamine, polycarbonate resin (Panlite (registered trademark),
1 part by weight of Teijin Limited and 1 part of tetrahydrofuran
A uniform solution consisting of 0 parts by weight was applied by a bar coater and dried to form a charge transport layer having a film thickness of 15 μm.

The characteristics of the electrophotographic photosensitive member thus prepared were evaluated as follows using an electrostatic copying paper test apparatus (EPA-8100, manufactured by Kawaguchi Electric Co., Ltd.). First, a corona discharge of -6 KV was applied to make it negatively charged, and then left in the dark for 2 seconds, and the surface potential Vpo (vol
t), and then, using a tungsten lamp, irradiate light so that the illuminance on the surface becomes 5 lux, and determine the time until the surface potential becomes 1/2 of Vpo. (lux · sec) was calculated. Further, the surface potential 4 seconds after the light irradiation was taken as VR. Furthermore, the same measurement was repeated 200 times. The results are shown in Table 1.

Example 2 The same as in Example 1 except that 4,4′-diaminobiphenyl represented by the following formula (4) was used in place of p-diphenylamine of the vapor deposition source B in Example 1. Then, an electrophotographic photosensitive member was prepared, and characteristics were evaluated in the same manner. Table 1 shows the results.

[0041]

Comparative Examples 1 and 2 1 part by weight of polyvinyl butyral resin (trade name: BLX, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 40 parts by weight of cyclohexane, and the above formula (1) (Comparative Example 1) or A compound represented by the following formula (5) (Comparative Example 2) was mixed in an amount of 4 parts by weight, then well dispersed by a paint shaker, and the obtained dispersion was applied onto an aluminum sheet by an applicator and dried to form a film. A charge generation layer having a thickness of 0.5 μm was formed. A charge transport layer was formed in the same manner as in Example 1 to prepare an electrophotographic photosensitive member, and the characteristics were evaluated in the same manner. The results are shown in Table 1.

[0043]

[0044]

[Table 1]

Example 3 The electrophotographic photosensitive member produced in Example 1 was wrapped around an aluminum pipe, and an electrophotographic copying machine (FX-270 was used.
0, made by Fuji Xerox Co., Ltd., 35 ° C, 85
After repeating charging and discharging 5000 times in an environment of% RH, a copy image was created by a normal electrophotographic process and evaluated. As a result, white and black spots on the black original part and white original part, and background It was confirmed that a good image without defects such as stains can be obtained.

Comparative Example 3 Using the electrophotographic photosensitive member prepared in Comparative Example 2,
When a copy image was prepared in the same manner as in Example 3 and evaluated in the same manner, white spots were produced in the black original portion and black spots were produced in the white original portion.

[0047]

The electrophotographic photoreceptor of the present invention has high photosensitivity, high chargeability, low dark decay, low residual potential, and durability such as stability of charge potential during repeated use. Is also excellent. Further, according to the manufacturing method of the present invention, when the charge generation layer is formed by vapor deposition, the impurities of the organic pigment introduced into the vapor deposition source can be controlled in the vapor deposition step. Therefore, even if a commercially available or untreated organic pigment is used, the electrophotographic characteristics of the produced electrophotographic photosensitive member can be stabilized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of a vacuum vapor deposition polymerization apparatus used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 vacuum chamber 2 substrate 3 and 4 evaporation container 5 and 6 evaporation heater 7 and 8 shutter 9 substrate heating heater 10 high vacuum valve 11 vacuum exhaust device 12 film thickness monitor 13 nitrogen cylinder 14 gas introduction valve A and B evaporation source

Front page continued (72) Inventor Hiroyuki Hotta 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji-Zerox Corporation Takematsu Plant (72) Inventor Ken-ichi Kobayashi 2274 Hongo, Ebina-shi, Kanagawa Fuji-Zerox Corporation Ebina Plant (72 ) Inventor Takayuki Yamada 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Works (72) Inventor Hitoshi Kojima 2274 Hongo, Ebina City, Kanagawa Fuji Xerox Co., Ltd. Ebina Works (56) Reference 2-251858 (JP, A)

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a photoconductive layer containing an organic photoconductive substance as a main component on a conductive substrate, wherein the charge generating material of the photoconductive layer is represented by the following formula (I): An electrophotographic photoreceptor comprising a polymer compound having a plurality of perylene skeletons each having a repeating structural unit shown in the main chain. Embedded image 2. A photoconductive layer comprising a layer formed by a vacuum vapor deposition polymerization method using a perylene tetracarboxylic acid anhydride represented by the following formula (II) and an aromatic diamine compound represented by the following formula (III). The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member comprises or comprises the layer. H ₂ N—R—NH ₂ (III) (In the formula, R has the same meaning as described above.)