JP2000075509A - Electrophotographic photoreceptor for negative electrification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photoreceptor excellent in producibility, which is inter changeable, in electrical properties, with the conventional laminated electrophotographic sensitive body and has a desired image characteristic by incorporating an amount of a specified range, based on a binding resin, of an electron-transporting material into the photosensitive layer. SOLUTION: An electric charge generating materials 2, an electron- transporting material and a hole-transporting material together with a binding resin are incorporated in a photosensitive layer 4, wherein the electron- transporting material is added within an amount of 1-2 parts by mass per 1 part by mass of the binding resin. In this case, it is, especially, preferable to incorporate the hole-transporting material into the photosensitive layer 4 in an amount of 0.1-0.5 parts by mass per 1 part by mass of the binding resin. Diphenoxy compounds and/or fluorenylidene malononitrile compounds are suitable as the electron-transporting materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor for electrophotography used in a copying machine or various printers, and more particularly, to a photoreceptor having good productivity and excellent negative charging characteristics. .

[0002]

2. Description of the Related Art In general, an electrophotographic photosensitive member is formed by forming a photosensitive layer made of a photoconductive material on a conductive substrate. In many cases, a laminated electrophotographic photosensitive member having a function-separated type photoconductive layer composed of a charge transport layer is used.

[0003] However, a conventional general laminated electrophotographic photoreceptor generally has a charge transport layer composed of a relatively thick layer laminated on a thin charge-generating layer having a thickness of 1 μm or less. The difficulty of forming a thin film causes a decrease in yield. The charge transporting material used for the charge transporting layer is generally a hole transporting material because of the abundance of compounds, electrical stability, safety as a material, and the like. Such a laminated electrophotographic photosensitive member inevitably can exhibit sensitivity only by negative charging.

In recent years, demands for electrophotographic photoreceptors tend to be higher in functions such as longer life and higher sensitivity, while demands for lower cost and higher productivity, like other general-purpose products, are extremely persistent.

In response to such demands for the electrophotographic photoreceptor, a conventional single-layer type electrophotographic photoreceptor which can achieve low cost and high productivity due to its advantages such as a simple layer structure is re-evaluated. It is becoming. Therefore, attempts to realize a practical single-layer electrophotographic photosensitive member have been actively made again, but a single-layer electrophotographic photosensitive member that is compatible with a conventional multilayer electrophotographic photosensitive member has been actively developed. At present, no body has been obtained.

[0006] For example, a single-layer electrophotographic method using a poly-N-vinylcarbazole (PVK) / trinitrofluorenone (TNF) complex disclosed in US Pat. No. 3,484,237, which was first practically used as an organic compound. The body has problems such as insufficient mechanical strength of PVK, which is a main component, poor sensitivity due to low charge mobility, and strong toxicity of TNF.

[0007] Also, "Journal of Applied
Physics ”(Journal of Applied Physics) No. 49
Vol. 11, No. 5543-5564 (1978) and the like, a single-layer type electrophotographic photoreceptor using a hole transport material in combination with a eutectic of a thiapyrylium salt and a polycarbonate resin is usable. Because it is limited, it is difficult to improve the characteristics, and the sensitivity wavelength range is narrow, and there is no sensitivity in the long wavelength range, so it is not applicable to electrophotographic devices that use semiconductor lasers that are currently the mainstream as exposure light sources. there were.

Further, as in the phthalocyanine / resin dispersion type electrophotographic photoreceptor disclosed in US Pat. No. 3,397,086, a single-layer type electron having a structure in which a photoconductive pigment is dispersed in an electrically insulating binder. Since the photoreceptor has a high density of charge traps inevitably formed on the pigment surface in the photosensitive layer, the photoresponse characteristics are significantly deteriorated due to a so-called induction effect in which a delay occurs from light irradiation to potential decay. Further, there is a disadvantage that the light attenuation curve is completely different from that of the ordinary laminated type photoreceptor, and compatibility of gradation cannot be obtained. In addition, when used repeatedly, there is also a problem that the charge is accumulated in the trap and the induction effect itself changes, so that stable characteristics cannot be obtained. For this reason, this type of single-layer type electrophotographic photosensitive member is currently used only as a disposable plate-making photosensitive member.

Thus, for example, Japanese Patent Application Laid-Open No. 54-1633 discloses a charge-generating substance such as phthalocyanine of 0.005.
A photosensitive composition obtained by dispersing about 0.15 mol part in a binder resin together with 1 mol part of a hole transporting substance such as oxadiazole and 0.05-0.3 mol part of an electron transporting substance such as dinitrofluorenone. A single-layer electrophotographic photosensitive member having a layer provided on a conductive support is disclosed. This type of single-layer type electrophotographic photoreceptor is different from a conventional phthalocyanine / resin dispersion type single-layer type electrophotographic photoreceptor in that charge generation and charge transport are performed by the same material. Since the generation is performed by different materials, the concentration of the charge generation substance can be significantly reduced as compared with the conventional case, and the induction effect which has been a problem in the single-layer type photoreceptor is not observed. In addition, there is an advantage that a photosensitive member having both positive and negative charges can be realized.

However, in the technology disclosed above, although the photoreceptor has both positive and negative charging properties, it has been developed mainly for use in positive charging. This is only about half of that of the conventional photoconductor, and does not match the sensitivity at all with the laminated photoconductor conventionally used with negative charging. In addition, in the single-layer type electrophotographic photoreceptor having such a configuration, since charge generation occurs in the photosensitive layer, electrons having low mobility are easily trapped, and the light attenuation characteristic shows a unique tailing tendency. However, even if only sensitization could be sensitized, compatible characteristics could not be obtained.

As an improvement, a technique in which an electron transporting substance is contained in a photosensitive layer in a larger amount than a hole transporting substance is disclosed in, for example, JP-A-7-191474. However, even in these techniques, since the electron transporting substance basically contains only 50% by mass or less of the photosensitive layer, an electron transporting substance such as a hole transporting substance which is essentially difficult to obtain a high transporting substance is used. The electron mobility is much lower than the hole mobility of the conventional photoreceptor, and it is difficult to obtain satisfactory electrical compatibility.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member that can be manufactured at low cost and with high productivity. An object of the present invention is to provide an electrophotographic photoreceptor for negative charging having preferable performance excellent in compatibility with the above-mentioned characteristics.

[0013]

According to the present invention, there is provided an electrophotographic photosensitive member comprising a charge generating material, an electron transporting material and a hole transporting material together with a binder resin in the same photosensitive layer. Wherein the photosensitive layer contains the electron transporting substance in an amount of 1 to 2 parts by mass with respect to 1 part by mass of the binder resin. In order to achieve the object of the present invention, it is particularly desirable that the photosensitive layer contains a hole transporting substance in an amount of 0.1 to 0.5 part by mass with respect to 1 part by mass of the binder resin. . Further, a diphenoxy-based compound and / or a fluorenylidene-malononitrile-based compound are preferably used as the electron transporting substance.

[0014]

FIG. 1 shows an example of the structure of the photosensitive layer of the electrophotographic photosensitive member of the present invention. Here, the thickness of the photosensitive layer is
A range of 5 to 50 μm is preferred. When the photosensitive layer is formed by dip coating, a desired thickness can be easily obtained by adjusting various physical properties such as a coating speed, a viscosity of a paint, and a shearing force. In addition to the single-layer photosensitive layer, a functional layer such as an intermediate layer or a surface protective layer may be appropriately used.

In the electrophotographic photoreceptor of the present invention, it is necessary to contain the electron transporting substance in the range of 1 to 2 parts by mass with respect to 1 part by mass of the binder resin. For this purpose, a large amount of an electron transporting material having good compatibility with the resin must be contained in the photosensitive layer. In addition, it is possible to use the electron transporting substance alone as the charge transporting substance. However, in this case, the holes generated in the bulk easily accumulate, so that the residual potential tends to increase. To prevent this, it is effective to add a hole transport material.
In particular, the hole transporting substance is added to the binder resin in an amount of 0.1 part by mass.
It is desirable to make it contain in the range of 1 to 0.5 part by mass.

When the amount of the electron transporting material is 1 part by mass or less with respect to 1 part by mass of the binder resin, the electron mobility of the photosensitive layer is reduced by the number of holes in the charge transporting layer of the conventional negatively charged laminated electrophotographic photosensitive member. , It is difficult to obtain electrical compatibility. On the other hand, according to the present invention, a large amount of the electron transfer material can be used. However, when the amount of the electron transport material is 2 parts by mass or more with respect to 1 part by mass of the binder resin, there are few materials having sufficient compatibility, and The mechanical strength also decreases rapidly.

On the other hand, if the amount of the hole transporting substance is less than 0.1 part by mass relative to 1 part by mass of the binder resin, the hole transporting ability becomes insufficient, so that the positive charges not transported into the photosensitive layer are left behind. , The residual potential tends to increase. Therefore, adverse effects such as a decrease in image density due to repetition are likely to occur. on the other hand,
When the amount of the hole transport material is 0.5 part by mass or more with respect to 1 part by mass of the binder resin, the ratio of the hole transport material or the electron transport material to be bound to the amount of the binder resin increases, and the amount of the binder resin is increased. Becomes insufficient. For this reason, the mechanical strength of the photosensitive layer decreases, and the photosensitive layer cannot withstand long-term use.

Examples of the electron transporting material include organic compounds such as benzoquinone, tetracyanoethylene, tetracyanoquinodimethane, fluorene, xanthone, phenanthraquinone, phthalic anhydride, and diphenoquinone. And inorganic materials such as amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc oxide and zinc sulfide. For the electrophotographic photoreceptor of the present invention, an electron transporting material having good solubility in a solvent and good compatibility with a resin is particularly preferably used. Examples of such a substance include, but are not limited to, diphenoquinone-based compounds, fluorenylidene-malononitrile-based compounds, and the like.

Examples of the hole transport material include low molecular weight compounds such as pyrene, carbazole, hydrazone, oxazole, oxadiazole, pyrazoline, arylamine, arylmethane, benzidine, and thiazole compounds. , Stilbene compounds, butadiene compounds and the like. Further, as the polymer compound, for example, poly-N-vinylcarbazole, halogenated poly-
Examples include N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, and polysilane.

The charge transporting material used in the present invention is not limited to those listed here, and can be used alone or in combination of two or more. A mixture of transport substances can also be used.

The charge generating substance used in the present invention includes:
For example, azo pigments, quinone pigments, perylene pigments,
Indigo pigment, thioindigo pigment, bisbenzimidazole pigment, phthalocyanine pigment, quinacridone pigment, quinoline pigment, lake pigment, azo lake pigment, anthraquinone pigment, oxazine pigment, dioxazine pigment, triphenylmethane pigment Pigments, azulenium dyes, squarium dyes, pyrylium dyes, triallylmethane dyes, xanthene dyes, thiazine dyes, various organic pigments such as cyanine dyes, dyes, and further amorphous silicon, selenium, tellurium, Inorganic materials such as selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc oxide and zinc sulfide can be given.

When the charge generating substance is used, the substances mentioned here can be used alone, but two or more kinds of charge generating substances can be mixed and used.

In the method of forming the photosensitive layer of the present invention, a coating liquid is obtained by dispersing an electron transporting substance, a hole transporting substance, a charge generating substance, a binder resin, and a solvent using a ball mill, a homomixer or the like. Apply the coating liquid. As the coating method, a known method such as a dip coating method, a roll coating method, a spray method, or a spin coating method can be appropriately selected. The ratio of the charge generating substance to the solid content in the paint is
The range of 0.2 to 5% by mass at which the sensitivity of the electrophotographic photoreceptor is good and the charge retention ability and the charge transportability are good is preferred.

The binder resin is preferably a high molecular polymer capable of forming an electrically insulating film. Such high-molecular polymers, for example, polycarbonate, polyester,
Methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride
Acrylonitrile polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole , Polyvinyl butyral, polyvinyl formal, polysulfone, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenolic resin, polyamide, carboxy-methyl cellulose, vinylidene chloride-based polymer latex, polyurethane, and the like, but are not limited thereto. These binder resins are used alone or in combination of two or more.

In addition to these binder resins, additives such as a dispersion stabilizer, a plasticizer, a surface modifier, an antioxidant, and a light degradation inhibitor can be used.

Examples of the plasticizer include biphenyl, biphenyl chloride, terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenylphosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, polypropylene, polystyrene, and various fluorohydrocarbons. No.

Examples of the surface modifier include silicone oil, fluororesin and the like.

Examples of the antioxidant include phenol-based, sulfur-based, phosphorus-based, and amine-based compounds.

Examples of the photo-deterioration inhibitor include benzotriazole compounds, benzophenone compounds, hindered amine compounds and the like.

Examples of the solvent used in the coating preparation method of the present invention include alcohols such as methanol, ethanol and n-propanol; acetone, methyl ethyl ketone,
Ketones such as cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; ethers such as tetrahydrofuran, dioxane and methyl cellosolve; esters such as methyl acetate and ethyl acetate; dimethyl sulfoxide, sulfolane and the like Sulfoxides and sulfones; aliphatic halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, and trichloroethane; and aromatics such as benzene, toluene, xylene, monochlorobenzene, and dichlorobenzene.

The electrophotographic photoreceptor for negative charging of the present invention can achieve low cost and high productivity due to its simple layer structure. Further, contrary to the conventional single-layer type electrophotographic photoreceptor, the photosensitive layer It has a remarkable feature that the mobility of electrons in it can be as high as or higher than the mobility of holes in a general laminated photoreceptor. Practically preferable characteristics having good compatibility and excellent image quality are realized. The reason will be described below.

In the prior art, if not only the electron transporting substance but also the hole transporting substance is contained in an excessive amount in the photosensitive layer, it is separated from the resin, resulting in remarkable electric characteristics and mechanical strength. It has been considered that it is essential to contain at least 50% by mass of a resin in the photosensitive layer because of deterioration in characteristics. For example, Japanese Patent Application Laid-Open No.
In the technique disclosed in, for example, Japanese Patent No. 1474, in which the electron transporting substance is contained in the photosensitive layer in a larger amount than the hole transporting substance, the electron transporting substance basically contains only 50% by mass or less of the photosensitive layer. However, in general, a high transporting substance such as a hole transporting substance is difficult to obtain from an electron transporting substance. The electron mobility was significantly inferior to the hole mobility, and there was a practical problem.

The present inventors have conducted intensive studies on the optimum blending amount of the resin and the electron transporting substance. As a result, in the case of a combination showing particularly good compatibility, the electron transporting amount far exceeds the conventional common sense blending amount. It has been found that a significant improvement in properties can be achieved by including a substance, and the present invention has been achieved.

The negatively charged electrophotographic photoreceptor of the present invention contains a large amount of an electron transporting substance, so that the electron mobility becomes so good that it cannot be seen in the conventional photoreceptor, and the charge generation at the time of the negative charge is reduced. A remarkable effect is obtained in the vicinity of the surface of the photosensitive layer, which can exhibit high-speed photo-responsiveness. Therefore, it is not necessary for the incident light to pass through the photosensitive layer to the vicinity of the substrate.
Loss is small and high sensitivity can be realized. Also,
Since most of the charge is generated in the portion closest to the charged charge, the charge is less likely to accumulate in the bulk, and light attenuation characteristics equivalent to those of the conventional negative-type stacked electrophotographic photoreceptor are obtained. There is a feature that compatibility in electrical characteristics is easily obtained.

Further, the electrophotographic photosensitive member for negative charging of the present invention is extremely advantageous from the viewpoint of image formation. That is, since the charge generation at the time of negative charging is performed in the vicinity of the surface of the photosensitive layer, the incident light is transmitted to the vicinity of the substrate as in the case of a conventional single-layer type electrophotographic photosensitive member or a laminated type electrophotographic photosensitive member. In addition, since there is no absorption or scattering in the photosensitive layer, and no charge is diffused before moving from the substrate side to the surface, a high-resolution latent image can be obtained.

Further, in the case of a photosensitive layer mainly having a hole transporting property, such as a conventional single-layer type electrophotographic photoreceptor, in the case of negative charging, holes injected from the substrate side easily reach the surface and charge. In many cases, the potential holding ability cannot be sufficiently obtained. In addition, if the substrate has dirt or defects, it becomes a nucleus for charge injection, causing a local potential drop, which is known to cause fatal black spots and background dirt defects in the reversal development method. I have. On the other hand, in the single-layer type electrophotographic photoreceptor of the present invention, electron transport is dominant, and such hole injection from the substrate side hardly occurs. There is an effect that a perfect image can be obtained.

The typical chemical composition (mass ratio) of the present invention is as follows. Charge generating substance 0.4 to 2.0 parts Electron transporting substance 10 to 20 parts Hole transporting substance 1 to 5 parts Binder resin 10 parts The above composition is dissolved and dispersed in an organic solvent and applied to a conductive support. . Further, a dispersion stabilizer, a plasticizer, a surface modifier, an antioxidant, a photo-deterioration inhibitor and the like may be added to the above composition, dispersed and made into a paint, and applied to a conductive support to form an electrophotographic photoreceptor. .

[0038]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the examples. In the following examples and comparative examples, “parts” indicates “parts by mass”.

(Example 1) 0.5 part of α-type titanyl phthalocyanine,

Formula (1) as an electron transport material

Embedded image

Diphenoquinone-based compound 15
Department,

Equation (2)

Embedded image

And 4 parts of a hole transport material represented by the following formula: and a polycarbonate resin ("Iupilon Z-Plate" manufactured by Mitsubishi Gas Chemical Company, Inc.).
200 ") 10 parts were dissolved in 70 parts of chloroform and dispersed using a vibration mill to prepare a coating for a photoreceptor.

Using this paint, dip coating was applied to the surface of a 30 mm-diameter aluminum pipe so that the film thickness after drying was 15 μm, and then dried to form a photosensitive layer. I got Further, a plate-shaped electrophotographic photosensitive member having a similar photosensitive layer formed on an aluminum plate having a thickness of 0.3 mm using the same coating material was also manufactured.

Example 2 An electrophotographic photosensitive member was obtained in the same manner as in Example 1, except that the electron transporting material was changed to 11 parts and the hole transporting material was changed to 4 parts.

Example 3 In Example 1, the compound represented by the formula (3) was used as an electron transporting substance.

[0047]

Embedded image

The diphenoquinone compound represented by
Department,

As the hole transporting material, the formula (4)

Embedded image

An electrophotographic photoreceptor was obtained in the same manner as in Example 1 except that 4 parts of the compound represented by the following formula was used.

(Example 4) In Example 1, an electron transporting material represented by the formula (5)

[0052]

Embedded image

An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 15 parts of the fluorenylidene-malononitrile compound represented by the following formula was used and 3 parts of the compound represented by the formula (4) were used as the hole transporting substance. Obtained.

Comparative Example 1 An electrophotographic photosensitive member was obtained in the same manner as in Example 1, except that 1.5 parts of the electron transport material and 8 parts of the hole transport material were used.

Comparative Example 2 An electrophotographic photosensitive member was obtained in the same manner as in Example 3, except that 2 parts of the electron transporting material and 7 parts of the hole transporting material were used.

Comparative Example 3 An electrophotographic photosensitive member was obtained in the same manner as in Example 3, except that the electron transporting material was changed to 5 parts and the hole transporting material was changed to 4 parts.

(Comparative Example 4) 2 parts of α-type titanyl phthalocyanine and 1 part of polyvinyl butyral resin (trade name “Eslec BM-1” manufactured by Sekisui Chemical Co., Ltd.) were dispersed together with 100 parts of methylene chloride in a vibration mill for 2 hours. A paint for a charge generation layer was prepared.

Next, using this paint, it is applied on an aluminum tube and an aluminum plate, and after drying, a film thickness of 0.4 μm
Was formed.

On the charge generation layer, a coating solution obtained by dissolving 8 parts of the hole transporting material of the formula (2) together with 10 parts of a polycarbonate resin (“Iupilon Z-200” manufactured by Mitsubishi Gas Chemical Company) in 60 parts of chloroform. 15μ after coating and drying
m to form a charge transport layer, thereby obtaining a laminated electrophotographic photosensitive member for negative charging.

(Electrical Characteristics) In order to evaluate the electrical characteristics of the electrophotographic photosensitive members obtained in each of the examples and comparative examples, each of the drum photosensitive members was tested using a drum photosensitive member tester (“Cynthia-30” manufactured by Gentec). ") Was used to measure the electrophotographic properties. The measuring method was such that the drum photosensitive member was charged at an applied voltage of -1200 V by contact with a conductive rubber roller while rotating at 60 rpm in a dark place, and the surface potential immediately after this was used as an initial potential V0 for evaluation of charging ability. Next, in the dark place
After standing for 0 second, the potential V10 was measured, and the potential holding ability was evaluated by V10 / V0. Then, the exposure intensity on the surface was set to 1 μW / cm ² with 780 nm monochromatic light, the photosensitive layer was irradiated with light, and the decay curve of the surface potential was recorded. Here, the surface potential is changed to V10 by light irradiation.
Exposure amount was determined until it was reduced to 1/5, and the sensitivity was evaluated as an evaluation exposure amount E1 / 5. The results are summarized in Table 1. Note that E1 / 5 reflects the sensitivity characteristics in the low electric field region better than the half-life exposure amount E1 / 2 usually used, and corresponds to the potential of the exposed portion which strongly affects the image density and the like. In the case where compatibility of electrophotographic characteristics is a problem as in the present invention, this is a suitable index.

[0061]

[Table 1]

As is apparent from the results shown in Table 1, the electrophotographic photosensitive members obtained in Examples 1 to 4 of the present invention exhibited excellent charging ability and sensitivity. In addition, each electrophotographic characteristic is very close to the conventional electrophotographic photosensitive member for negative charging having a conventional configuration in which the charge generation layer and the charge transport layer obtained in Comparative Example 4 are laminated in this order, and the compatibility is excellent. I understand. On the other hand, Comparative Example 1
A photoreceptor having a ratio of the electron transporting material to the resin of 1 or less, a photoreceptor in which the electron transporting material obtained in Comparative Example 2 has a lower concentration than the hole transporting material, and a hole mobility obtained in Comparative Example 3 The photoreceptors having the same electron mobility as those of the electrophotographic photoreceptors obtained in each of Examples and Comparative Example 4 are significantly inferior in sensitivity,
It is clear that sufficient compatibility cannot be obtained.

(Image Characteristics) To evaluate the image characteristics, a reversal developing laser printer (Laser Jet “Laser Jet” 5Si manufactured by Hewlett-Packard Company) corresponding to a negatively charged drum-shaped electrophotographic photosensitive member was used. Example 1
4 and the drum-shaped electrophotographic photosensitive members obtained in Comparative Examples 1 to 4 were mounted, and an image was formed on copy paper which is usually used in an environment of 23 ° C. and 50% RH. Table 2 summarizes the image evaluation results. In addition, the evaluation regarding the soil
Observe the original with a 50x magnifying glass on the white background
The ratio of the area to which the toner adhered in the square of 2 mm × 2 mm was determined, and the evaluation was made in four stages of ◎, ○, Δ, and × according to the following evaluation criteria.

A: The maximum value of the area ratio is less than 0.1%. ：: The maximum value of the area ratio is 0.1% or more and less than 0.5%. Δ: The maximum value of the area ratio was 0.5% or more and less than 1.0%. ×: The maximum value of the area ratio is 1.0% or more.

The image density was measured by measuring the print density of the black background portion of the image with a densitometer (RD918, manufactured by Macbeth).

[0066]

[Table 2]

As is clear from the results shown in Table 2, each of the electrophotographic photosensitive members obtained in Examples 1 to 4 was free from background smear and an image having a sufficient print density was obtained. Example 1
In the electrophotographic photoreceptors obtained in Nos. 1 to 3, not only the image density was significantly inferior, but also the evaluation of background contamination was insufficient.
In the conventional electrophotographic photosensitive member having a laminated structure obtained in Comparative Example 4, although sufficient image density was obtained, the evaluation of background contamination was very poor.

Further, when the resolutions of the printed images consisting of halftone dots were compared, the electrophotographic photoreceptors obtained in Comparative Examples 1 and 2 were unsatisfactory in resolution because the halftone dots were destroyed. Indicate excellent dot reproducibility,
It has been found that good resolution can be obtained.

[0069]

According to the electrophotographic photoreceptor for negative charging of the present invention, the cost can be reduced and the productivity can be increased because of its simple layer structure. Practically preferable characteristics that have compatibility and have high image quality in which no defects appear on the image are realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an example of a layer configuration of an electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive support 2 charge generating substance 3 charge transporting substance + binder resin 4 photosensitive layer

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising a charge generating substance, an electron transporting substance and a hole transporting substance together with a binder resin in the same photosensitive layer, wherein the photosensitive layer comprises the binder resin and the electron transporting substance. An electrophotographic photoreceptor characterized in that it is contained in an amount of 1 to 2 parts by mass relative to parts by mass. 2. A photosensitive layer comprising: a hole transporting substance;
2. The electrophotographic photoconductor according to claim 1, wherein the content is in the range of 0.1 to 0.5 part by mass with respect to part by mass. 3. The method according to claim 1, wherein the electron transporting substance is a diphenoquinone-based compound and / or a fluorenylidene-malononitrile-based compound.
Electrophotographic photoreceptor.