JPH11194591A - Process cartridge, electrophotographic device and electrophotographic photoreceptor used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge excellent in durability capable of regularly providing a high quality image in a repeated electrophotographic process by setting the potential difference between charge potential and developing bias potential in non-exposure in a developing position. SOLUTION: The potential difference between charge potential and developing bias potential in non-exposure in a developing position is set to 200 v or more. An electrophotographic photoreceptor having a support body, an under coating layer and a photosensitive layer is used, and it is designed so as to have a field intensity of 30 v/l μm or less and an initial film pressure of photosensitive layer of 17 μm or less. According to such a structure, the reproducibility of independent dot is improved, and even if the charge potential is reduced by repeated use, a clear image free from fogging can be provided since the charge potential is lower than the developing bias by 200 v or more, for example, in reverse development. Further, polytetrafluoroethylene resin particles may be included in the photosensitive layer in order to reduce the scraping quantity of the photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge, an electrophotographic apparatus, and an electrophotographic photosensitive member used for the same.

[0002]

2. Description of the Related Art An electrophotographic method is disclosed in U.S. Pat.
As shown in JP-A No. 1 (1993), a photoconductive material comprising a support coated with an insulating substance is used in which the electric resistance changes in accordance with the amount of irradiation received during image exposure, and in a dark place. The basic characteristics required of an electrophotographic photoreceptor using this photoconductive material include (1) that it can be charged to an appropriate potential in a dark place, (2) that there is little dissipation of the potential in a dark place, 3) Quickly dissipating the charge by light irradiation.

[0003] Conventionally, selenium,
Inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive compound such as zinc oxide and cadmium sulfide have been widely used. However, they satisfy the above conditions (1) to (3), but are not always satisfactory in heat stability, moisture resistance, durability and productivity.

In order to overcome the disadvantages of inorganic photoconductors, electrophotographic photoconductors containing various organic photoconductive compounds as main components have been actively developed in recent years. For example, US Pat.
No. 7851 discloses a photoreceptor having a charge transport layer containing triallylpyrazolin, and US Pat.
No. 0 discloses a photoreceptor comprising a charge generation layer comprising a derivative of a perylene pigment and a charge transport layer comprising a condensate of 3-propylene and formaldehyde.

Further, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound.
The substances disclosed in JP-A-2754 and JP-A-56-167759 have high sensitivity in the visible region, and are disclosed in JP-A-57-19576 and JP-A-61-228.
The compound disclosed in Japanese Patent No. 453 has sensitivity up to the infrared region.

[0006] Of these materials, those exhibiting sensitivity in the infrared region are used in laser beam printers (hereinafter abbreviated as LBPs) and LED printers, which have been remarkably advanced in recent years, and the demand frequency thereof is increasing. Electrophotographic photoreceptors using these organic photoconductive compounds are sometimes used as function-separated type photoreceptors in which a charge transport layer and a charge generation layer are laminated in order to satisfy both electrical and mechanical properties. Many.
On the other hand, it is needless to say that the electrophotographic photoreceptor is required to have sensitivity, electrical characteristics, and even optical characteristics according to the electrophotographic process applied.

In particular, in the case of an electrophotographic photoreceptor that is used repeatedly, the surface of the electrophotographic photoreceptor is directly subjected to an electrical or mechanical external force such as corona or direct charging, image exposure, toner development, transfer step and surface cleaning. Therefore, durability for them is also required.

[0008] More specifically, mechanical deterioration such as surface wear or scratching due to discharge at the time of charging or rubbing of the cleaning member, and electric field strength of the photosensitive layer increases due to wear of the surface layer, resulting in leakage current In other words, there is a demand for durability against electrical deterioration in which the dark potential of the photoreceptor increases and the charged potential cannot be maintained.

The mechanical deterioration is particularly different from inorganic photosensitive members, and organic photosensitive members, which are often soft in material and have poor durability against mechanical deterioration, are particularly desired to improve the durability.

Various attempts have been made to satisfy the durability required for the photoreceptor as described above.

As a resin often used for the surface layer and having good abrasion and electric properties, a polycarbonate resin having bisphenol A as a skeleton has been attracting attention. However, not all of the above-mentioned problems can be solved, and many The problem remains.

Further, in recent years, a direct charging system in which a voltage is applied directly to a charging member and a charge is applied to an electrophotographic photosensitive member as disclosed in JP-A-57-17826 and JP-A-58-40566. Is becoming mainstream.

This is a method in which a roller-shaped charging member made of conductive rubber or the like is brought into direct contact with an electrophotographic photosensitive member to apply an electric charge. The amount of ozone generated is significantly smaller than that of a scorotron or the like. Although about 80% of the current flowing through the charger flows through the shield, it is wasted, whereas direct charging has the advantage that it is very economical without this waste.

However, direct charging has a disadvantage that charging stability is very poor because of charging by discharge according to Paschen's rule. As a countermeasure, a so-called AC / DC charging method in which an AC voltage is superimposed on a DC voltage has been devised (Japanese Patent Application Laid-Open No. 63-149668).

Although the stability of the photoreceptor at the time of initial charging is improved by this charging method, the amount of discharge on the surface of the electrophotographic photoreceptor is greatly increased due to the superposition of AC, and the shaving amount of the electrophotographic photoreceptor is reduced. This has resulted in a new disadvantage that the potential is unstable. Therefore, an electrophotographic apparatus and a process cartridge having excellent durability even by these charging methods have been desired.

[0016]

In view of the above, in order to obtain the durability stability, the thickness of the photosensitive layer is made thicker than before so as to achieve the durability stability in AC / DC charging. However, in this case, as the photosensitive layer thickness increased, the capacitance of the photosensitive layer decreased, the charge amount during charging decreased, and the reproducibility of isolated dots in an image decreased.

In order to reduce the shaving amount of the photosensitive layer, the photosensitive layer is formed of polytetrafluoroethylene (PTFE).
When the surface energy of the photosensitive layer is increased by dispersing the resin particles, the durability stability against abrasion is improved, but the light at the time of exposure is scattered by the polytetrafluoroethylene resin particles, and this is coupled with the decrease in surface charge due to the thick film. And the image quality was further reduced.

Conversely, in order to avoid these problems, when the initial photosensitive layer thickness is set to 20 μm or less, the initial image quality is good, but the electrostatic capacity of the photosensitive layer is large, The flowing current increases, and the shaving amount also increases.
By repeating this, the capacitance further increases, the dark decay of the charging potential also increases, the charging potential decreases, and image fogging occurs. The general thickness of the photosensitive layer that causes this image fogging is from 8 μm to 14 μm.
m, the initial film thickness setting is 18 μm or more,
Preferably, 20 μm or more was required.

The general thickness of the photosensitive layer that causes image fogging is often 10 μm or less, but the minimum thickness of the photosensitive layer that must be ensured depends on the image output environment and the roughness of the photosensitive layer surface. In order to maintain good images, it is necessary to design a process cartridge in consideration of the remaining film thickness of 12 μm or more (final remaining film thickness).

There has been a demand for a process cartridge, an electrophotographic apparatus, and an electrophotographic photosensitive member used for the process cartridge, which have good reproducibility of these isolated dots and excellent durability characteristics.

An object of the present invention is to provide a process cartridge, an electrophotographic apparatus, and an electrophotographic photoreceptor used in the process cartridge, which can always obtain a high-quality image in repeated electrophotographic processes and have excellent durability.

[0022]

That is, the present invention provides a method for charging,
In a process cartridge having at least an exposure and development process, a potential difference between a non-exposure charging potential and a development bias potential at a development position is 200 V or more. It is a photoreceptor. With this configuration, stable potential characteristics and image characteristics can be obtained even when used repeatedly.

In the above process cartridge, the electrophotographic apparatus and the electrophotographic photosensitive member used therein, preferably, an electrophotographic photosensitive member having a support, an undercoat layer and a photosensitive layer is used, and the electric field strength is 30 v / 1 μm. The initial setting thickness of the photosensitive layer is 17 μm or less, and the final remaining thickness of the photosensitive layer is designed to be 9 μm or less.
With this configuration, the reproducibility of the isolated dot is improved. Further, even if the charging potential is reduced by repeated use, for example, in the case of reversal development, the charging potential is two times lower than the developing bias potential.
Since it is lower than 00v, a clear image without fog can be obtained.

Further, even if the photosensitive layer contains polytetrafluoroethylene resin particles in order to reduce the shaving amount of the photosensitive layer, if the photosensitive layer has a thickness of 17 μm or less,
Light scattering during exposure by polytetrafluoroethylene resin particles is extremely small.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an electrophotographic photosensitive member used in the present invention will be described below.

In the electrophotographic photoreceptor of the present invention, even if the photosensitive layer is a single-layer type containing a charge transporting substance and a charge generating substance in the same layer, the charge transporting layer containing the charge transporting substance and the charge generating substance May be separated into a charge-generating layer containing, but from the standpoint of electrophotographic characteristics, a stacked type is preferable.

The support to be used may be any one having conductivity, such as a metal such as aluminum and stainless steel, or a metal provided with a conductive layer, paper and plastic. No.

When the image input is a laser beam, such as LBP, a conductive layer may be provided for the purpose of preventing interference fringes due to scattering and covering a scratch on the support. This can be formed by dispersing a conductive powder such as carbon black or metal particles in a binder resin. The thickness of the conductive layer is preferably 5 to 40 μm, more preferably 10 to 30 μm.
It is.

Next, an undercoat layer is provided, which may be an alumite-treated aluminum cylinder or an undercoat layer having an adhesive function. Polyamide,
Examples thereof include polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane, but are not limited thereto, and a metal powder or a metal oxide powder may be further dispersed. These are applied by dissolving in an appropriate solvent. The thickness of the intermediate layer is preferably 0.3 μm or more, more preferably 0.3 to 20 μm.

The charge generation layer is formed on the intermediate layer. The charge generating substance used in the present invention is selenium-
Tellurium, pyrylium, thiapyrylium dye, phthalocyanine, anthrone, dibenzopyrenequinone, trisazo, cyanine, disazo, monoazo, indigo,
Examples include quinacridone and asymmetric quinocyanine pigments. In the case of the function-separated type, the charge generation layer is formed by mixing the charge generation substance with a binder resin and a solvent in an amount of 0.3 to 4 times the amount of a homogenizer, an ultrasonic dispersion, a ball mill, a vibration ball mill, a sand mill, an attritor, a roll mill, and a liquid collision type high speed. It is formed by dispersing well by a method such as a disperser, applying a dispersion, and drying. The thickness of the charge generation layer is preferably 5 μm or less, more preferably 0.1 to 2 μm.

The charge transport layer is formed by applying and drying a coating material in which a charge transport material and a binder resin of the present invention are dissolved in a solvent. Examples of the charge transport material used include triarylamine compounds, hydrazone compounds,
Examples include stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

These are combined with 0.5 to 2 times the amount of the binder resin, coated and dried to form a charge transport layer. The thickness of the charge transport layer is preferably 8 to 17 μm.

The binder resin used for the charge transport layer is a thermoplastic resin such as a polycarbonate resin, a polyarylate resin, an acrylic resin, a polyester resin, a polyamide resin, a polyvinyl acetate resin and a polyvinyl butyral resin; a polyurethane resin, a phenol resin and an epoxy resin. Thermosetting resin: light-curing resin, etc., but not limited thereto.

In recent years, a polycarbonate resin is particularly often used as a binder excellent in the scraping property and transparency of the binder. However, other common bisphenols and copolymers such as bisphenol Z, bisphenol A, bisphenol C and bisphenol AF are used. These can be applied to the electrophotographic photosensitive member, electrophotographic apparatus, and process cartridge of the present invention.

Further, another binder resin can be added as required. Examples of other binder resins include thermoplastic resins such as polycarbonate resins, polyarylate resins, acrylic resins, polyester resins, polyamide resins, polyvinyl acetate resins and polyvinyl butyral resins; and thermoplastic resins such as polyurethane resins, phenol resins and epoxy resins. Curable resin; photocurable resin;

Conventionally, a photosensitive layer having a thickness of 20 μm or more was used in order to maintain durability stability by repeated use.
This had the disadvantage that the electrostatic capacity of the photosensitive layer was reduced and it was difficult to obtain a good image.However, by adding an anti-wear agent or a lubricant such as fluororesin particles to the charge transport layer, the durability characteristics were stabilized. Can be achieved. Examples of the fluororesin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin and difluoroethylene chloride resin. One of these alone or 2
More than one type may be mixed. Moreover, you may mix with antiwear agents and lubricants other than the above.

The particle size and molecular weight of the fluororesin particles can be appropriately selected and are not particularly limited.

The ratio of the fluororesin particles in the surface layer is appropriately selected depending on the type of the fluororesin particles and the constitution of the photosensitive layer. If the amount of addition is large, the light transmittance is reduced, the sensitivity is reduced, and the image exposure light is scattered to cause bleeding of the image, which causes adverse effects. On the other hand, if the addition amount is small, it is liable to be worn and the effect of the present invention cannot be sufficiently obtained. It is preferably from 0.1 to 50% by weight, particularly preferably from 0.5 to 40% by weight, based on the surface layer. Further, additives such as a dispersing aid can be added as needed.

Among the dispersion aids for the fluorine-based resin particles, particularly preferred are fluorine-based comb type graft polymers. The fluorine-based comb-type graft polymer has a molecular weight of 100 having a polymerizable functional group at one end of each molecular chain.
It is obtained by copolymerizing a macromonomer consisting of a relatively low molecular weight oligomer of about 0 to 10000 and a fluorine-based polymerizable monomer, and the polymer of the macromonomer hangs in a branch shape with the fluorine-based polymer as a trunk. It has a structure.

The macromonomer is selected from those having affinity for the resin to which the graft polymer is added. For example, polymers or copolymers of acrylic esters, methacrylic esters or styrene compounds are used.

On the other hand, as the fluorine-based polymerizable monomer, one or more polymerizable monomers having a fluorine atom in a side chain as shown in the following (1) to (5) are used, but the present invention is not limited thereto. Not something.

[0042]

Embedded image (Wherein, R ₁ represents a hydrogen atom and a methyl group; R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, and a nitrile group, and may be a combination of several types thereof.
n represents an integer of 1 or more, m represents an integer of 1 to 5, k represents an integer of 1 to 4, and m + k = 5. )

The content of the fluorine-based comb type graft polymer is suitably 0.01 to 10% based on the weight of the solid content, and particularly preferably 0.02 to 2%. If it is less than 0.01%, the effect of improving the dispersibility is insufficient, while if it exceeds 10%, the graft polymer tends to be present not only on the surface of the coating film but also in the bulk. Accumulation of residual charges during repeated electrophotographic processes is likely to occur.

In forming the surface layer, generally, the above-mentioned fluorine-based resin particles are dispersed in the above-mentioned binder resin, and a charge transporting substance and a solvent are added thereto to prepare a coating solution, which is coated by a coating means and exposed to light. Make a body. As the solvent used at this time, it is preferable to select a solvent having good solubility in the binder resin and the charge transport material and good dispersibility of the fluororesin particles. Particularly good examples include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone, ethers such as diethyl ether and tetrahydrofuran, esters such as ethyl acetate and butyl acetate, hydrocarbons such as toluene and benzene, and And halogenated hydrocarbons such as chlorobenzene and dichloromethane.

As a method for preparing a coating solution for forming the surface layer of the electrophotographic photoreceptor of the present invention, fluorine resin particles, a charge transport material and a binder resin may be simultaneously dispersed together with a solvent. Alternatively, a coating liquid may be prepared by preparing a dispersion liquid in which the fluororesin particles and the binder resin are dispersed in advance, and mixing the dispersion liquid with a liquid in which the binder resin and the charge transport material are dissolved in advance. In the preparation of the coating solution for the electrophotographic photoreceptor used in the present invention, or a fluorinated resin particle dispersion, it may be simply stirred and mixed, but if necessary, using a dispersing means such as a ball mill, a roll mill, a sand mill and a high-pressure homogenizer. Is also good. Ideally, the dispersed particle size is close to the intrinsic primary particle size of the fluororesin particles used and has a uniform distribution.

The electrophotographic photoreceptor thus obtained is mounted on the LBP main body or a detachable process cartridge, and at least can be charged, exposed, developed and transferred to form an image.

The thickness of the photosensitive layer of the electrophotographic photosensitive member used in the electrophotographic apparatus and the process cartridge of the present invention is 1
FIG. 1 (gradation characteristics of a polytetrafluoroethylene drum) shows detailed data for which the diameter is preferably 7 μm or less. In FIG. 1, 1
The reproducibility of the isolated dots was evaluated by a 200 dpi LC dither (1 ″ is divided into 64 and the image density of each dot is measured). From the figure, B, C and D to which polytetrafluoroethylene is added are shown. The gamma characteristic of the photosensitive layer having a film thickness of 25 μm is as follows.
It can be seen that the inclination is large and the dot reproducibility is reduced as compared with. Conventionally, when the film thickness is increased and the amount of polytetrafluoroethylene is increased for the purpose of securing the life of the photosensitive member, it can be seen that the reproducibility of dots has been reduced. However, regardless of the amount of polytetrafluoroethylene, when the film pressure of the photosensitive layer is 17 μm or less, the dot reproducibility is improved.

FIG. 2 shows a schematic configuration of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention.

In the figure, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is driven to rotate around a shaft 2 at a predetermined peripheral speed in a direction indicated by an arrow. The photoreceptor 1 rotates during the rotation process.
The peripheral surface thereof is uniformly charged with a predetermined positive or negative potential by the primary charging unit 3 and then receives image exposure light 4 from an image exposure unit (not shown) such as slit exposure or laser beam scanning exposure. Thus, an electrostatic latent image is sequentially formed on the peripheral surface of the photoconductor 1.

The formed electrostatic latent image is then developed.
The toner image developed is transferred from the paper supply unit (not shown) to the transfer material 7 fed out between the photoconductor 1 and the transfer unit 6 in synchronization with the rotation of the photoconductor 1 and fed. The image is sequentially transferred by the means 6.

The transfer material 7 having undergone the image transfer is separated from the surface of the photoreceptor, introduced into the image fixing means 8 and subjected to image fixing, thereby being printed out of the apparatus as a copy.

The surface of the photoreceptor 1 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 9, and further, the pre-exposure light 10 from the pre-exposure means (not shown).
Is used for image formation repeatedly after the charge removal processing. When the primary charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the primary charging means 3, the developing means 5 and the cleaning means 9 are integrally connected as a process cartridge. The process cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported together with the photoreceptor 1 to form a cartridge, which can be attached to and detached from the apparatus main body using a guide unit such as a rail 12 of the apparatus main body. The process cartridge 11 can be used.

When the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is read and transmitted from the original, or the original is read by a sensor and converted into a signal, and the exposure is performed according to the signal. Laser beam scanning,
Light emitted by driving the LED array, driving the liquid crystal shutter array, and the like.

The electrophotographic photosensitive member of the present invention can be used not only for an electrophotographic copying machine, but also for a laser beam printer, C
It can be widely used in electrophotographic applications such as RT printers, LED printers, liquid crystal printers, and laser plate making.

A description will be given below in accordance with embodiments. In the examples,
“Parts” indicates parts by weight. [Example 1] A 30φ, 254mm aluminum cylinder was used as a support, and a coating composed of the following materials was applied on the support by a dip coating method.
For 30 minutes to form a conductive layer having a thickness of 15 μm.

Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: titanium oxide 2 parts Binder resin: phenol resin 6 parts Leveling material: silicone oil 0.001 parts Solvent: methanol, methoxypropanol 0.2 / 0.8 20 parts

Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymerized nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied thereon by dip coating. An intermediate layer of 0.65 μm was formed.

Next, in the CuKα characteristic X-ray diffraction, the Bragg angles 2θ ± 0.2 ° of 9.0 °, 14.2 °, 2 °
4 parts of oxytitanium phthalocyanine (TiOPc) having strong peaks at 3.9 ° and 27.1 °, 2 parts of polyvinyl butyral (Eslec BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were mixed with a sand mill using φ1 mm glass beads. After dispersion for 4 hours, 100 parts of ethyl acetate was added to prepare a dispersion for charge generation layer.
This is applied by the dip coating method, and the film thickness is 0.3μ.
m of the charge generation layer was formed.

Next, as a process for preparing a fluororesin particle dispersion,

Polyfluoroethylene resin powder (Rublon L-2, manufactured by Daikin Industries, Ltd.) 25 parts Bisphenol Z-type polycarbonate 25 parts (Iupilon Z400, manufactured by Mitsubishi Gas Chemical Company) Comb-type graft polymer (GF-300, Toa Gosei Co., Ltd.) 1 part) Monochlorobenzene 75 parts

After sufficiently mixing the mixture, the mixture was dispersed for 4 hours by a sand mill using φ1 mm glass beads to prepare a fluororesin particle dispersion.

Next, 9 parts of an amine compound having the following structural formula:

[0064]

Embedded image 1 part of a styryl compound of the following structural formula,

[0065]

Embedded image 10 parts of the above polycarbonate and 12.5 parts of the fluororesin particle dispersion were dissolved in a mixed solvent of 30 parts of monochlorobenzene and 70 parts of dichloromethane. The content of the fluororesin particles with respect to the solid content is 10% by weight.

This paint is applied by a dip coating method,
After drying at 120 ° C. for 2 hours, a charge transport layer having a thickness of 8 μm was formed.

Next, the evaluation will be described.

The device is a Hewlett-Packard LBP
"Laser jet 4plus" (process speed 7
1 mm / sec). In the remodeling, primary charging was controlled by constant current control and constant voltage control. The charging potential is 60
0 V, the developing bias potential is 300 V, and the potential at the time of exposure is 1
It adjusted so that it might be set to 20v. The prepared electrophotographic photoreceptor was subjected to a paper-passing durability test at 28 ° C. and 90% RH using this apparatus, and the results are shown in Table 3.

In order to check whether or not the image pattern of the first rotation of the photoconductor remains as the same pattern in the second rotation under the environment of 10 ° C. and 10% RH,
The character pattern was exposed on the first rotation of the photoreceptor, and the second and subsequent rotations were output as halftone images. If the photoreceptor has a memory phenomenon, the image pattern in the first rotation also appears in the halftone image in the second rotation. (L / L ghost test)

[Example 2-6] An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the charge transport layer and the undercoat layer had thicknesses from conditions 2 to 6 in Table 2. did. Furthermore,
The charging potential setting and the developing bias potential were also set and evaluated in the same manner as in Example 1 except that the conditions 2 to 6 in Table 1 were changed.
Table 2 shows the results.

Example 7 An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that the content of the fluorine-based resin particles in the surface layer was changed to 20% by weight. Further, the charging potential is set to 550
The evaluation was performed in the same manner as in Example 1 except for setting the developing bias potential and the developing bias potential to 300 V. The results are shown in Table 2.

Example 8 An electrophotographic photosensitive member was prepared in the same manner as in Example 4, except that the surface layer was formed without adding the fluororesin particles to the surface layer. Further, the charging potential is set to 550
The evaluation was performed in the same manner as in Example 1 except for setting the developing bias potential and the developing bias potential to 300 V. The results are shown in Table 2.

Example 9 According to the procedure of Example 1, a solution prepared by dissolving 5 parts of a copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied by dip coating according to the procedure of Example 1. An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that an intermediate layer having a thickness of 1.50 μm was formed, and the thickness of the surface layer was changed to 6 μm. Further, when the charging potential is 6
Evaluation was performed in the same manner as in Example 1 except that the developing bias potential was 400 V and the potential at the time of exposure was 200 V. Table 2 shows the results.

Example 10 According to the procedure of Example 1, TiOPc used for the charge generation layer was changed to 9.5 °, 9.7 ° of 2θ ± 0.2 ° of the Bragg angle of characteristic X-ray diffraction of CuKα,
An electrophotographic photoreceptor was prepared in the same manner as in Example 3, except that the charge generation layer was formed using TiOPc having strong peaks at 11.7 °, 15.0 °, 24.1 ° and 27.3 °. . This is applied with a charging potential of 450 V and a developing bias potential of 2
The same evaluation as in Example 1 was performed by setting 30 V and the potential at the time of exposure to 50 V. Table 2 shows the results.

[Comparative Example 1-2] A dip coating method was applied on an aluminum cylinder coated with a charge generating layer in the same manner as in Example 1 and dried at 120 ° C. for 2 hours.
m of the charge transport layer was formed.

The electrophotographic photosensitive member was charged at a charging potential of 450 V.
The evaluation was performed in the same manner as in Example 1 except that Table 2 shows the results.

Comparative Example 3 The charge transport layer was 25 μm thick.
An electrophotographic photoreceptor was prepared in the same manner as in Example 8, except that This electrophotographic photosensitive member was evaluated in the same manner as in Comparative Example 1. Table 2 shows the results.

Comparative Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 2, except that the charging potential was set at 450 V and the developing bias potential was set at 300 V. This electrophotographic photosensitive member was evaluated in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 5 An electrophotographic photosensitive member was prepared in the same manner as in Example 10, except that the charging potential was set at 300 V and the developing bias potential was set at 130 V. This electrophotographic photosensitive member was evaluated in the same manner as in Example 1. Table 2 shows the results.

[0080]

[Table 1]

[0081]

[Table 2]

[0082]

According to the process cartridge, the electrophotographic apparatus and the electrophotographic photosensitive member used in the present invention, it is possible to obtain stable potential characteristics and image characteristics even after repeated use. In addition, the reproducibility of isolated dots is improved, and even if the charging potential is reduced by repeated use, for example, in the case of reversal development, the charging potential is lower than the developing bias potential by 200 V or more, so that clear fog without fogging is obtained. It became possible to obtain a perfect image. Further, even if the photosensitive layer contains polytetrafluoroethylene resin particles in order to reduce the shaving amount of the photosensitive layer, when the photosensitive layer has a thickness of 17 μm or less, the photosensitive layer is exposed to polytetrafluoroethylene resin particles. Light scattering can be extremely reduced. Furthermore, the ghost image generated under low temperature and low humidity is extremely small, and a good image can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between polytetrafluoroethylene resin particle content and film thickness and gradation.

FIG. 2 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus having a process cartridge having an electrophotographic photosensitive member according to the present invention.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/02 102 G03G 15/00 556 (72) Inventor Kunihiko Sekido 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Inside

Claims (18)

[Claims] In a process cartridge having at least a process of charging, exposing and developing, a potential difference between a charging potential at a non-exposure time at a developing position and a developing bias potential is 2
A process cartridge characterized by being at least 00v. 2. A process cartridge having at least a charging, exposing and developing process, wherein a potential difference between a charging potential at a developing position and a developing bias potential at the time of non-exposure is 2.
A process cartridge having a charging setting of not less than 00 V and an electric field intensity applied to the photosensitive layer of the electrophotographic photosensitive member of not less than 30 v / 1 μm. 3. The process cartridge according to claim 1, further comprising an electrophotographic photosensitive member having a support, an undercoat layer, and a photosensitive layer, wherein said photosensitive layer has an initial thickness of 17 μm or less. 4. An electrophotographic photoreceptor having a support, an undercoat layer and a photosensitive layer, wherein the initial thickness of the photosensitive layer is 17 μm or less, and the final remaining thickness of the photosensitive layer is 9 μm or less. The process cartridge according to claim 1, wherein the process cartridge is designed as follows. 5. The process cartridge according to claim 3, wherein the surface layer of the electrophotographic photosensitive member contains fluorine resin particles. 6. A surface layer of the electrophotographic photoreceptor contains fluorine resin particles, and the fluorine resin particles are formed of a tetrafluoroethylene resin, a trifluoroethylene chloride resin, a hexafluoroethylenepropylene resin, The process cartridge according to claim 3, comprising one or more resins selected from a vinyl resin, a vinylidene fluoride resin, a difluorinated ethylene chloride resin, and a copolymer thereof. 7. The surface layer of the electrophotographic photosensitive member contains fluorine resin particles, and the content of the fluorine resin particles is 0.1 to 50% by weight based on the total solid content of the surface layer. 5. The process cartridge according to 3 or 4. 8. The process cartridge according to claim 3, wherein the surface layer of the electrophotographic photosensitive member contains a fluorine-based comb type graft polymer. 9. An electrophotographic apparatus having at least the steps of charging, exposing, and developing, wherein a potential difference between a charging potential at the time of non-exposure at a developing position and a developing bias potential is 200 V or more. 10. An electrophotographic apparatus having at least the steps of charging, exposing and developing, wherein the potential difference between the non-exposed charging potential and the developing bias potential at the developing position is 200V.
An electrophotographic apparatus characterized in that the electric field intensity applied to the photosensitive layer of the electrophotographic photosensitive member is set to 30 v / 1 μm or more. 11. It has a support, an undercoat layer and a photosensitive layer,
The electrophotographic apparatus according to claim 9, further comprising an electrophotographic photosensitive member having an initial thickness of 17 μm or less. 12. It has a support, an undercoat layer and a photosensitive layer,
The electrophotographic apparatus according to claim 9, further comprising an electrophotographic photosensitive member having an initial set thickness of the photosensitive layer of 17 μm or less, and a final remaining thickness of the photosensitive layer designed to be 9 μm or less. 13. The electrophotographic apparatus according to claim 11, wherein the surface layer of the electrophotographic photosensitive member contains fluorine-based resin particles. 14. The surface layer of the electrophotographic photoreceptor contains fluorine resin particles, and the fluorine resin particles are a tetrafluoroethylene resin, a trifluoride ethylene chloride resin, a hexafluoroethylene propylene resin, 13. The electrophotographic apparatus according to claim 11, comprising one or more resins selected from a vinyl resin, a vinylidene fluoride resin, a difluoroethylene chloride resin, and a copolymer thereof. 15. The surface layer of the electrophotographic photoreceptor contains fluorine resin particles, and the content of the fluorine resin particles is:
The amount is 0.1 to 50% by weight based on the total solid content of the surface layer.
13. The electrophotographic apparatus according to 1 or 12. 16. The electrophotographic apparatus according to claim 11, wherein the surface layer of the electrophotographic photosensitive member contains a fluorine-based comb type graft polymer. 17. An electrophotographic photosensitive member used for the process cartridge according to claim 1. Description: 18. An electrophotographic photosensitive member used in the electrophotographic apparatus according to claim 9. Description: