JPH09211876A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain such an electrophotographic photoreceptor that shows high gamma characteristics with stability against repetition of use and stability against environmental changes, that has enough optical response which can endure against fast rotation and that production of ghosts can be suppressed, and moreover, to obtain a photoreceptor showing high gamma characteristics with negative polarity for which a developer used for a conventional negative charge-type photoreceptor can also be used. SOLUTION: This photoreceptor consists of a conductive base body 12, a charge generating layer 16 containing a phthalocyanine compd., and a P-type charge transfer layer 18 adjacent to the charge generating layer 16. The P-type charge transfer layer 18 consists of a material which is selected from inorg. P-type semiconductors, t-Se fine powder and charge transfer polynaers and does not contain hole transfer molecules.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoconductor having an exposure device such as a semiconductor radar or an LED array and used in an electrophotographic device for forming an electrostatic latent image by a digitized signal. .

[0002]

2. Description of the Related Art In a light source such as a semiconductor laser, its exposure distribution generally has a Gaussian shape, that is, it has a photocurrent increasing characteristic similar to an increase in exposure amount.
It has been difficult to obtain a high gamma characteristic in which the electrostatic latent image intensity is dramatically increased as compared with the increase in exposure amount. As a solution to this problem, for example, Japanese Patent Publication No. 5-191
No. 40 discloses that an intrinsic semiconductor fine powder of 0.01 to 0.5 μm is dispersed in a binder of 10 ¹³ Ωcm or more, and 5
A so-called high-gamma single-layer type photoreceptor is disclosed which utilizes the avalanche phenomenon that occurs in a photoreceptor having a thickness of -30 μm.

With such a photoreceptor, it is possible to achieve a high gamma characteristic suitable for digital light input, but since it is a single-layer photoreceptor having a charge generating function and a charge transporting function in the same layer, it is bulky. The trapping of mobile carriers (holes) by the charge-generating agent in the layer causes repeated characteristics, in particular, (1) increase in residual potential at low temperature, and (2) charging potential at high temperature due to free carrier emission in dark place. Decline, (3)
Problems such as poor pulse light response occur. Further, similarly, there is a problem that a ghost phenomenon in which the previous print image slightly remains on the next print image is caused due to the trap of the moving carrier. In addition, the conventional high-gamma photoconductor has a limitation of forming a P-type single-layer photoconductor, and is limited to the positive charging type photoconductor, and limits the polarity of the developer that can be used.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a repeating stability, a high gamma characteristic that is stable against environmental changes, and an optical response speed that can withstand high speed rotation.
An object of the present invention is to provide a photoconductor capable of suppressing the generation of ghost. Further, in addition to the above characteristics, an object of the present invention is a negative polarity type photoreceptor in which a developer used in a conventional negative charging type photoreceptor can be used as it is, and a photoreceptor exhibiting a high gamma characteristic. To provide.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, as a result of intensive studies, it was found that a charge-transporting layer formed of a material containing no substance inhibiting high gamma characteristics is formed adjacent to the charge-generating layer. The present invention has been completed by finding that an electrophotographic photosensitive member which is a laminated type and can achieve each of the above characteristics can be obtained.

That is, the electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a charge generating layer containing a phthalocyanine compound and a charge transporting layer.
Type charge transport layer is formed, and the P type charge transport layer is
It is characterized by being composed of a material containing no hole transporting molecule selected from the group consisting of an inorganic P-type semiconductor, a fine powder of t-Se, and a charge transporting polymer.

The electrophotographic photosensitive member is characterized in that the rate of decay of the surface potential under uniform and normal exposure after charging becomes steeper as the exposure amount increases than immediately after exposure.

The constitution of the electrophotographic photosensitive member of the present invention is as follows:
It is preferable that at least a charge generation layer is formed on a conductive substrate, and a charge transport layer is laminated adjacent to the charge generation layer.
Further, the thickness of the charge generation layer is preferably in the range of 0.1 to 5 μm.

The content of the phthalocyanine compound in the charge generation layer is 10 to 50% by weight.

The gamma (γ) value in the present invention is
The formed image density and the electrostatic latent image intensity are set to have a correspondence relationship.

The high gamma characteristic of the electrophotographic photosensitive member of the present invention is obtained by charging the photosensitive member, and after charging, it is uniform and normal, that is, a constant intensity (for example, about 1 lux) is continuous. It should be confirmed by the phenomenon that the decay rate of surface potential under exposure does not increase in proportion to the increase in the exposure amount in direct proportion to the increase in the exposure amount, but rather increases dramatically with the increase in the exposure amount. You can

The electrophotographic photoreceptor of the present invention is of a laminated type, and is composed of a charge transporting layer containing no hole transporting molecule adjacent to the charge generating layer. Transportable molecules do not diffuse. Therefore, the phthalocyanine pigment was used to suppress traps, the charge potential was lowered due to the release of free carriers, and the ghost was reduced. Further, it is possible to combine materials having large drift mobility as the charge transport layer, and it is possible to achieve high gamma characteristics with excellent high-speed response, and it is possible to obtain a negative charging type high gamma characteristics photosensitive member.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The constitution of the present invention will be described in detail below.

The electrophotographic photosensitive member of the present invention is preferably
At least a charge generation layer is formed on a conductive substrate, and a charge transport layer is laminated adjacent to the charge generation layer.
As the conductive support that is the base of the electrophotographic photosensitive member, all materials used in conventional electrophotographic photosensitive members can be used, and examples thereof include metals such as aluminum, nickel, chromium, and stainless steel, and Conductive, such as paper or plastic film coated or impregnated with a conductivity-imparting agent, such as a plastic film provided with a thin film of aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, ITO, etc. A resin or the like can be used. These conductive supports are used in a suitable shape such as a drum shape, a sheet shape, and a plate shape, but are not limited thereto. Further, if necessary, the surface of the conductive support is
Various types of processing can be performed within a range that does not affect the image quality. For example, surface oxidation treatment, chemical treatment, coloring treatment, or irregular reflection treatment such as graining can be performed.

As the charge generation layer, a metal and metal-free phthalocyanine compound which is a highly loaded compound having high gamma characteristics, for example, copper phthalocyanine, X.
It is necessary to include type metal-free phthalocyanine, titanyl phthalocyanine, chloroindium phthalocyanine, hydroxygallium phthalocyanine, etc. as the charge generating material. Of these, Japanese Patent Application Laid-Open No. 5-2-2200 having a specific crystal
Particularly preferred are hydroxygallium phthalocyanine described in 6300, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine described in JP-A-5-98181.

This charge generation layer is preferably composed of the phthalocyanine pigment and a binder resin, and the ratio of the phthalocyanine pigment and the resin is 1: n (n is 1 or more), preferably 1 from the viewpoint of achieving high gamma characteristics. : It is necessary to adjust to around 3.

That is, these phthalocyanine compounds are
The charge generation layer preferably contains 10 to 50% by weight, more preferably 20 to 40% by weight. If the content of the phthalocyanine compound is less than 10% by weight, the sensitivity becomes extremely low, and if it exceeds 50% by weight, the pigments come into contact with each other to form a conductive path and high gamma characteristics are lost, which is not preferable.

The charge generation layer is composed of a phthalocyanine compound which is the charge generation material and a binder resin. The binder resin can be selected from a wide range of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. As a preferable binder resin,
Polyvinyl acetal, polyarylate (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, acrylic resin, polyacrylamide, polyvinyl pyridine, cellulose resin, Insulating resins such as urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone can be used. Further, a resin that is soluble in the coating solvent of the charge transport layer that is laminated adjacently after the film formation is not preferable.

As a method for dispersing the phthalocyanine compound in the binder resin, a usual method such as a ball mill dispersion method, an attritor dispersion method or a sand mill dispersion method can be used. Conditions that do not change are required. At the time of dispersion, the phthalocyanine compound particles are 0.5 μm or less, preferably 0.3 μm or less,
More preferably, it is effective to set the particle size to 0.15 μm or less. Further, as the solvent used for dispersing these, methanol, ethanol, n-propanol, n
-Butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate,
Ordinary organic solvents such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene and toluene can be used alone or in combination of two or more. The thickness of the charge generation layer used in the present invention is generally 0.1 to 5 μm, preferably 0.2 to 2.0.
μm is appropriate.

The coating method used when the charge generating layer is provided is a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method or a curtain coating method. Can be used.

Next, the charge transport layer will be described. The charge-transporting layer is provided adjacent to the charge-generating layer, and the P-type charge-transporting layer in the electrophotographic photosensitive member of the present invention is a group consisting of an inorganic P-type semiconductor, t-Se fine powder, and a charge-transporting polymer. It is necessary that it is formed of a material containing one or more selected from the above, and that the material does not contain a hole transporting molecule.

The charge-transporting polymer exemplified as the material used for the P-type charge-transporting layer does not need to be mixed with a low-molecular component for charge-transporting, and has the possibility of greatly improving the mechanical strength. It is a material that has been actively studied. Examples of the charge-transporting polymer applicable to the present invention include polycarbonates obtained by polymerizing a specific dihydroxyarylamine and bischloroformate described in US Pat. No. 4,806,443, and US Pat. No. 4,806. , 444, a polycarbonate produced by polymerization of dihydroxyarylamine and phosgene,
Polycarbonates described in U.S. Pat. No. 4,801,517 by polymerization of bishydroxyalkylarylamine with bischloroformate or phosgene, U.S. Pat. Nos. 4,937,165 and 4,959,28.
No. 8, a polycarbonate produced by polymerization of a specific dihydroxyarylamine or bishydroxyalkylarylamine and bischloroformate, or a polyester produced by polymerization of bisacyl halide,
Arylamine polycarbonate or polyester having a specific fluorene skeleton described in US Pat. No. 5,034,296, US Pat. No. 4,983,48.
No. 2 specification polyurethane, Japanese Examined Patent Publication No. 59-289
No. 03, a polyester having a main chain of a specific bisstyrylbisarylamine, JP-A-61-2095
No. 3, JP-A-1-134456, JP-A-1-134456
JP-A-134457, JP-A-1-134462,
Japanese Unexamined Patent Publication No. Hei 4-133065, Hei 4-13306
Examples thereof include hydrazones described in Japanese Patent No. 6, etc., and polymers having pendant charge-transporting substituents such as triarylamine. Further, known charge transporting polymers such as polysilane and polysilylene can also be used. In particular, polymers having a tetraarylbenzidine skeleton are particularly referred to as “6th International Conference on Advances in Non-Impact Printing Technology (“ The Sixth In
ternational Congress on Advances in Non-impact Pri
nting Technologies. ”) Abstract, p. 306, (19
As reported in 1990), it has high mobility and is highly practical.

Further, Japanese Patent Application No. 6-151, which the applicant of the present application newly developed for an electrophotographic photoreceptor and has already applied for a patent.
No. 776, No. 6-219599, No. 6-334633.
High-performance charge-transporting polymers such as the novel charge-transporting polycarbonate resins and charge-transporting polyester resins described in JP-A No. 6-329853 and the like can also be used. These charge transporting polycarbonate resin and charge transporting polyester resin are particularly preferable because they have a function as a charge transporting layer without using any other low molecular weight charge transporting material.

Other materials used for the charge transport layer include inorganic selenium and inorganic P-type semiconductors such as selenium / tellurium alloys and selenium / arsenic alloys, and fine powder of t-Se (0.0
1 to 0.5 μm) is dispersed in a curable resin.

The hole-transporting molecules that should not be used in the charge-transporting layer adjacent to the charge-generating layer of the present invention include known low-molecular-weight charge-transporting materials.
For example, 2,5-bis (p-diethylaminophenyl)
Oxadiazole derivatives such as -1,3,4-oxadiazole and pyrazoline derivatives such as 1- [pyridyl- (2)-]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline , Triphenylamine, tri (p-methyl) phenylamine, N, N-
Aromatic tertiary amino compounds such as bis (3,4-dimethylphenyl) biphenyl-4-amine and dibenzylani,
Aromatic tertiary diamino compounds such as N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine, 4-diethylaminobenzaldehyde- Well-known charge transport materials such as hydrazone derivatives such as 1,1′-diphenylhydrazone and α-stilbene derivatives such as p- (2,2′-diphenylvinyl) -N, N-diphenylaniline can be used.

That is, the material for forming the charge-transporting layer used in the laminated electrophotographic photoreceptor of the present invention is only a material selected from the group consisting of the above-mentioned inorganic P-type semiconductor, t-Se fine powder and charge-transporting polymer. Is a charge transport material, it is important not to include other so-called low-molecular charge transport material,
In other words, solvents that are not related to charge transport properties,
Except for the compounding ingredients necessary for layer formation, inorganic P-type semiconductors, t
It is preferable that the main component is only a material selected from a fine powder of —Se and a charge transporting polymer.

The thickness of the charge transport layer is not particularly limited, and it can be formed in a range generally used, for example, 5 to 50 μm, preferably 10 to 35 μm.

As a coating method used when the charge transport layer is provided, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method and a curtain coating method is used. Any method can be used. As a solvent used for coating, a usual organic solvent such as dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene can be used alone or in combination of two or more kinds.

[0029]

EXAMPLE The basic structure of the electrophotographic photosensitive member of Example 1 of the present invention is shown in FIG. 1 as a schematic sectional view. Electrophotographic photoreceptor 10
Forms an undercoat layer 14 on a conductive base material 12, forms a charge generation layer 16 containing a phthalocyanine compound thereon, and adjoins the charge generation layer 16 to form a P-type charge transport layer 18
It is configured by stacking.

FIG. 2 shows another electrophotographic photosensitive member 2 according to the present invention.
2 is a schematic cross-sectional view showing a specific example of No. 0. In this electrophotographic photosensitive member 20, a surface protective layer 22 is further provided on the uppermost layer of the electrophotographic photosensitive member 10 of FIG. 1 to improve wear resistance. There is. Further, as in Example 20, a charge transport layer 24 in which the hole transporting low molecule is molecularly dispersed can be further laminated on the charge transporting layer 18 containing no hole transporting low molecule.

This is because if the charge transporting layer 18 in contact with the charge generating layer 16 containing the phthalocyanine compound contributing to high gamma characteristics does not contain the hole transporting molecule, the hole transporting molecule is separated from the other layers. This is because the effect of the present invention will not be impaired even if a layer containing the same (for example, the charge transport layer 24 of this example) is formed.

Also in this second embodiment, the subbing layer 14 can be provided between the conductive base material 12 and the charge generation layer 16 to suppress the charge injection from the conductive base material 12. When the charge injection is not particularly required to be suppressed, the undercoat layer 14 may be omitted from the viewpoint of cost reduction in the electrophotographic photoreceptors shown in FIGS. 1 and 2.

The charge generation layer 16 is composed of a phthalocyanine pigment and a binder resin, and it is necessary to adjust the ratio of the phthalocyanine pigment and the resin to be 1: n (n is 1 or more) in order to achieve high gamma characteristics.

When aluminum is used as the electroconductive base material of these photoconductors, especially as the main material, the surface can be anodized to provide an anodized film for the purpose of preventing leakage during contact charging.

The constitution of the electrophotographic photosensitive member of the present invention is not limited to the above-mentioned specific examples, and for example,
By changing the stacking order in each layer structure of the electrophotographic photosensitive member of FIG. 2, the conductive substrate 12-undercoat layer 14-charge transport layer (layer containing hole transporting molecules) 24-charge transport layer (positive) A layer containing no hole-transporting molecule) 18-charge generation layer 16-surface protection layer 22 may be used. Although this modified example cannot provide a negative charging type photoconductor, as a positive charging type photoconductor, it exhibits repeated stability and high gamma characteristics that are stable against environmental changes, and has an optical response speed that can withstand high-speed rotation. It is possible to realize excellent characteristics that can suppress the occurrence of ghost.

The charge generation layer 16 is formed by vapor deposition such as in amorphous selenium, a transporting polymer such as polysilane and t-.
In the case of a curable resin in which a fine powder of Se is dispersed, it is possible to form a film by a method such as spray coating or dip coating.

As a modification, in the electrophotographic photoreceptor 20 of FIG. 2, the charge transport layer 18 containing no hole transporting low molecule, for example, the vapor deposition film of amorphous selenium can be made thin, so that the in-line vapor deposition is less likely to occur. There is an advantage that cost can be measured. In this specific example, by providing the same surface protective layer 22 as in Example 1, the wear resistance can be improved.

From another point of view, the electrophotographic photosensitive member 20 of FIG. 2 as a modified example is useful. A charge-transporting polymer containing no hole-transporting molecule other than amorphous selenium has a short hole life due to impurities as represented by polysilane. Even materials with a short life can be used, and the degree of freedom in material selection increases.

The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to these examples.

[Example 1] Diameter of 30 m as a conductive base material
A ring coating machine was used, in which an aluminum pipe 12 having a length of 253 mm was used, and 100 parts of a 50% tributoxyzirconium acetylacetate toluene solution, 10 parts of γ-aminopropyltriethoxysilane and 130 parts of n-butanol were mixed on the surface thereof. Apply at 140 ℃ 1
It was heated for 0 minutes to form a cured undercoat layer 14 having a thickness of 0.2 μm.

Next, a 2% cyclohexanone solution of polyvinyl butyral resin (trade name: BM-S, manufactured by Sekisui Chemical Co., Ltd.) was mixed with hydroxy potassium phthalocyanine pigment so that the weight ratio of the pigment and the resin was 1: 3, Dispersion was performed in a sand mill for 3 hours. The dispersion is further dispersed with n-butyl acetate and coated on the undercoat layer.
After drying for a minute, the charge generation layer 16 having a film thickness of 0.8 μm was formed.

Next, arsenic was added to 99.99% high-purity selenium.
4% selenium alloy containing 0.5 wt% and 50 ppm chlorine
On the drum on which the charge generation layer formed at 5 ° C. is formed
To 10 ^-FiveIt was melted by heating to 280 ° C in a torr vacuum.
Selenium alloy with a thickness of 38 μm
Layers as the top layer to form the charge transport layer 18 and
An electrophotographic photoreceptor 10 was obtained.

Comparative Example 1 A charge generation layer having the same structure as in Example 1 is formed on the undercoat layer formed in the same manner as in Example 1.
The electrophotographic photosensitive member was formed with a thickness of 7.0 μm.

[Comparative Example 2] On the charge generation layer produced in the same manner as in Example 1, instead of the charge transport layer in Example 1,
As a hole transporting molecule, N, N-diphenyl-N, N-
4 parts of bis (3-methylphenyl) benzidine and 6 parts of polycarbonate resin (molecular weight 32000) were dissolved in 36 parts of monochlorobenzene by a dip coating method, and dried at 135 ° C. for 40 minutes. Then, an electrophotographic photosensitive member having the same configuration as in Example 1 was prepared except that a charge transporting layer containing a hole transporting molecule having a film thickness of 18 μm was formed.

The electrophotographic characteristics of the three drum type electrophotographic photosensitive members were evaluated by the following methods.

First, irradiation of halogen lamp light having a color temperature of 2850 k with an intensity of 1 lux was started from a state of being controlled to an initial potential of −500 V (Example 1 and Comparative Example 2) or +500 V (Comparative Example 1). The state of decay of the surface potential after exposure for 10 seconds was examined by measuring the half-decay exposure time and the residual potential after 10 seconds of exposure. The results are shown in Table 1.

In addition, FIG. 3 shows a graph of PIDC (optical attenuation curve) measurement results showing the manner of attenuation of the surface potential of Example 1. From this graph and the measurement results, Example 1
It was confirmed that the electrophotographic photosensitive member of No. 1 had high gamma characteristics.

Next, the time required for the surface potential to reach a constant potential after the irradiation of pulsed light was measured. A xenon flash lamp with a half width of 1 μsec is used as a light source.
Used in combination with a colored glass filter that cuts 0 nm or less, an initial potential of −500 V (Example 1, Comparative Example 2).
Alternatively, the light attenuation process from +500 V (Comparative Example 1) was investigated. The time required to reach from 500V to 100V was measured. The results are shown in Table 1 below.

[0049]

[Table 1]

Finally, these drum electrophotographic photoconductors were transferred to Apple Computer (Apple Computer Inc.).
Leather Writer Select (Leather Writer Sel)
ect: Product name), high temperature and high humidity (28 ℃ 85%)
500 sheets were continuously printed under the environment, and further 500 sheets were continuously printed under the environment of low temperature and low humidity (15 ° C. 20%). In Comparative Example 1, the voltage polarity of the charger was changed to +, and the controller inputs a black and white inverted image signal. With respect to the obtained images, the presence or absence of ghost, the presence or absence of background fog, and the presence or absence of decrease in print density were evaluated. Table 2 shows the results.

[0051]

[Table 2]

As is clear from these results, in Comparative Example 2 which is a conventional standard organic photoconductor, although the formed image is good, it is high because of the relationship between the half decay exposure time and the residual potential. It was found that the gamma characteristic was not achieved. It is considered that this is because the electrophotographic photosensitive member of Comparative Example 2 was obtained by molecularly dispersing the hole transporting low molecule in the electron transporting layer laminated on the charge generating layer. That is, when an electron transporting layer in which low molecular weight hole transporting molecules are molecularly dispersed is applied in contact with the charge generating layer in a solution containing a solvent, the solvent causes the charge generating layer to swell at the time of coating, and the hole transporting molecule is charged. It diffuses into the generation layer. Therefore, when the hole transporting molecule enters the charge generating layer from the charge transporting layer, holes in the hole-electron pair generated in the phthalocyanine pigment confined by the binder resin are transferred to the hole transporting layer. The high gamma characteristic disappears as soon as it goes out of the pigment due to the sexual molecule.

On the other hand, Comparative Example 1 which is a conventional single-layer type high gamma photoreceptor also serves as a charge generation layer and a charge transport layer, and conversely, it is not possible to separate functions with high gamma characteristics. Therefore, from the relationship between the half-decayed exposure time and the residual potential, it was confirmed that the film has high gamma characteristics, but it was confirmed that the image characteristics obtained by repeated use significantly deteriorate.

As shown in Example 1, the electrophotographic photoreceptor of the present invention having a function-separated type, that is, a laminated type, having a high gamma characteristic is formed by laminating charge transport layers containing no hole transporting molecule. Therefore, the hole transporting molecule does not diffuse into the charge generation layer. Therefore, for example, it can be used by laminating a charge transporting layer for an organic photoreceptor, which has been conventionally used, on the selenium layer by a means such as contacting the thin film vapor-deposited selenium layer with the charge generating layer. Further, as is clear from these results, the high-speed response was excellent, the obtained image was good, and no decrease in image density or generation of fog ghost was observed even after repeated use.

[0055]

In the electrophotographic photoreceptor of the present invention, the charge generating layer and the charge transporting layer can be functionally separated from each other, so that the charge generating layer is thinned, and the phthalocyanine pigment traps and the free carrier, which have been problems so far, are present. It is possible to realize a high gamma characteristic with excellent high-speed response and a negative gamma type high gamma photoconductor, in which a decrease in charge potential due to emission is suppressed and a ghost is reduced, and a material having large drift mobility can be combined as a charge transport layer. It has achieved an excellent effect that a negative-polarity developer which has been practically used for an organic photoreceptor can be used as it is.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view of an electrophotographic photosensitive member of Example 1.

FIG. 2 is a partial schematic cross-sectional view of an electrophotographic photosensitive member provided with a charge transport layer containing no hole transporting low molecule and a charge transport layer containing hole transporting low molecule.

FIG. 3 is a graph of PIDC measurement results showing how the surface potential of the electrophotographic photosensitive member of Example 1 is attenuated.

[Explanation of symbols]

 10, 20 Electrophotographic Photoreceptor 16 Charge Generation Layer Containing Phthalocyanine Compound 18 Charge Transport Layer Containing No Hole Transporting Low Molecules 24 Charge Transport Layer Containing Hole Transporting Low Molecules

Claims (6)

[Claims] 1. An electrophotographic photoreceptor having a charge generation layer containing a phthalocyanine compound and a charge transport layer, wherein a P-type charge transport layer is formed adjacent to the charge generation layer, and the P-type charge transport layer. Is selected from the group consisting of an inorganic P-type semiconductor, a fine powder of t-Se, and a charge-transporting polymer, and
An electrophotographic photoreceptor comprising a material containing no hole transporting molecule. 2. The electrophotographic photosensitive member is characterized in that the rate of decay of the surface potential under uniform and normal exposure after charging becomes steeper as the amount of exposure increases than immediately after exposure. The electrophotographic photosensitive member described. 3. The P-type charge transport layer contains, as a charge-transporting material, only one or more selected from the group consisting of an inorganic P-type semiconductor, t-Se fine powder and a charge-transporting polymer. The electrophotographic photosensitive member according to claim 1. 4. The electrophotographic photosensitive member according to claim 1, wherein at least a charge generation layer is formed on a conductive substrate, and a charge transport layer is laminated adjacent to the charge generation layer. 5. The thickness of the charge generation layer is 0.1 to 5 μm.
The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is in the range of 1. 6. The electrophotographic photosensitive member according to claim 1, wherein the content of the phthalocyanine compound in the charge generation layer is 10 to 50% by weight.