JPH0990648A - Electrophotographic photoreceptor and process cartridge and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the mechanical strength without reducing solvent cracking resistance, to improve electrical characteristics in direct charging, and to facilitate the manufacture by incorporating a polymer having specified structural units in the surface layer of the photoreceptor. SOLUTION: The surface layer of the photoreceptor contains a polymer having a structural unit each represented by formula I in which each of R1 -R17 is, independently, at least one group selected from among H and halogen atoms, alkyl, aryl, and alkylidene groups each optionally substituted, and -O- and -S- groups. This polymer is prepared by stirring a mixture of a bisphenol represented by formula II and terephthalic chloride and isophthalic chloride in an alkaline solvent/water to make surface polymerization in order to enhance solubility. In the formula II, each of R1 -R16 is, independently, at least one group selected from H atom and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, a process cartridge and an electrophotographic apparatus, and more specifically, an electrophotographic photoreceptor having a photosensitive layer containing a specific resin,
And a process cartridge and an electrophotographic apparatus having the photoconductor.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member is disclosed in US Pat.
As shown in Japanese Patent No. 91, a photoconductive material is used, which comprises a support coated with an insulating substance in the dark, the electric resistance of which changes depending on the amount of irradiation received during image exposure. The basic characteristics required for an electrophotographic photoreceptor using this photoconductive material are (1) being able to be charged to an appropriate potential in a dark place, (2) having little potential dissipation in a dark place, ( 3) It is possible to quickly dissipate the electric charge by light irradiation.

Conventionally, selenium has been used as an electrophotographic photoreceptor.
Inorganic photoreceptors having a photosensitive layer containing an inorganic photoconductive compound such as zinc oxide and cadmium sulfide as a main component have been widely used. However, these satisfies the conditions (1) to (3), but are not necessarily satisfactory in thermal 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. 3,871,880 discloses a charge generating layer comprising a derivative of a perylene pigment and a charge comprising a condensation product of 3-propylene and formaldehyde. Photoconductors and the like comprising a transport layer are known.

Further, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound.
2754 and JP-A-56-167759 disclose substances exhibiting high sensitivity in the visible region, and JP-A-57-19576 and JP-A-61-22845.
Japanese Patent Publication No. 3 discloses a compound having sensitivity in the infrared region.

Of these materials, those exhibiting sensitivity in the infrared region are used in laser beam printers (hereinafter abbreviated as LBP) and LED printers, which have made remarkable progress in recent years, and their demand frequency is increasing.

Electrophotographic photoreceptors using these organic photoconductive compounds are 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. In many cases. On the other hand, as a matter of course, the electrophotographic photosensitive member is required to have sensitivity, electrical characteristics, and further optical characteristics according to the electrophotographic process applied.

Particularly in an electrophotographic photosensitive member which is repeatedly used, an electric or mechanical external force such as corona or direct charging, image exposure, toner development, transfer process, surface cleaning is directly applied to the surface of the electrophotographic photosensitive member. Therefore, durability against them is also required.

Specifically, electrical deterioration due to ozone and nitrogen oxides during charging, mechanical deterioration such as abrasion and scratches on the surface due to discharge during charging, rubbing of a cleaning member, and electrical deterioration Durability against deterioration is required.

[0010] The electrical deterioration is particularly problematic in that carriers stay in a portion irradiated with light and a potential difference is generated between the portion not irradiated with light and a photo memory.

Mechanical deterioration is particularly low in organic photoreceptors, which are different from inorganic photoreceptors in that they are often soft in terms of material, and durability against mechanical deterioration is inferior, and improvement in durability is particularly desired.

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

Polycarbonate resin having bisphenol A as a skeleton has been attracting attention as a resin which is often used for the surface layer and has good wear properties and electric characteristics. However, it cannot solve all the problems mentioned above and It has such a problem.

(1) It has poor solubility and shows good solubility only in a part of halogenated aliphatic hydrocarbons such as dichloromethane and 1.2-dichloroethane, and these solvents have a low boiling point. When a photoconductor is manufactured using a coating solution prepared with the above solvent, the coated surface is easily whitened. It takes time to control the solid content of the coating liquid.

(2) Tetrahydrafuran, dioxane, cyclohexanone or a mixed solvent thereof is partially soluble in solvents other than halogenated aliphatic hydrocarbons, but the solution gels in a few days. It is not suitable for manufacturing a photoconductor because of its poor aging property.

(3) Furthermore, even if the above (1) and (2) are improved, solvent cracks are easily generated in the polycarbonate resin having bisphenol A as a skeleton.

(4) In addition, in the conventional polycarbonate resin, since the film formed of the resin has no lubricity, the photoconductor is easily scratched, and the cleaning setting is set to reduce the abrasion amount of the electrophotographic photoconductor. Image defects may occur, cleaning defects may occur due to early deterioration of the cleaning blade, and toner fusion may occur.

Regarding the solution stability described in the above (1) and (2), a polycarbonate Z resin having a bulky cyclohexylene group as a structural unit of the polymer is used, or
It has been solved by copolymerizing with bisphenol Z, bisphenol C and the like.

Solvent cracks can also be solved by using silicon-modified polycarbonate or ether-modified polycarbonate as disclosed in JP-A-6-51544 and JP-A-6-75415. . However, since these modified polycarbonates have a structure that has flexibility against internal stress in the polymer in order to prevent salt cracks compared with conventional polycarbonate resins,
As a result, there is a drawback that the mechanical strength of the polymer body is lowered.

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

This is a method in which a roller-shaped charging member made of conductive rubber or the like is directly brought into contact with the electrophotographic photosensitive member to apply an electric charge, and the amount of ozone generated is much smaller than that of a scorotron. About 80% of the current passed through the charger is wasted because it flows through the shield, whereas direct charging has the merit that it is extremely economical without this wasted amount.

However, the direct charging has a drawback that the charging stability is very poor because it is charged by the discharge according to Paschen's law. 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).

This charging method improves the stability at the time of charging, but the amount of discharge on the surface of the electrophotographic photosensitive member is greatly increased due to the superposition of AC, so that the scraped amount of the electrophotographic photosensitive member is increased. A new problem has arisen, and not only mechanical strength but also electrical strength has come to be required.

[0024]

The object of the present invention is to solve the problem of having a conventional polycarbonate resin as a surface layer, to have a solvent crack resistance, a high mechanical strength, and a direct charging property. An object of the present invention is to provide an electrophotographic photosensitive member having good electric resistance and easy to manufacture, and a process cartridge and an electrophotographic apparatus having the photosensitive member.

[0025]

That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the surface layer of the photosensitive member is represented by the following general formula (1).

[0026]

[Outside 2] (In the formula, R _{1 to} R ₁₇ are the same or different and each represents a hydrogen atom,
At least one group selected from the group consisting of a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkylidene group, -O- and -S- is shown. And an electrophotographic photosensitive member containing a polymer having a structural unit represented by the formula (1).

The present invention also relates to a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member.

The halogen atom in the present invention includes a fluorine atom, a chlorine atom and a bromine atom, the alkyl group includes a methyl group, an ethyl group and a propyl group, and the aryl group includes a phenyl group. Examples of the alkylidene group include a cyclohexylidene group. In addition, examples of the substituent that these may have include the halogen atom, the alkyl group, and the aryl group as described above.

Specific examples of the structural unit represented by the general formula (1) are shown in Table 1, but not limited thereto.

[0030]

[Outside 3]

[0031]

[Outside 4]

Preferred examples are structural unit examples 1, 2 and
3, and structural units 1 and 2 are particularly preferable.

The polymer having the constitutional unit represented by the general formula (1) used in the present invention is obtained by converting the bisphenol represented by the following general formula (2) into a terephthalic acid chloride or an isophthalic acid chloride in order to increase the solubility. Interfacial polymerization can be carried out by stirring with a mixture of the substances under an alkali in a solvent / water system.

The ratio of terephthalic acid chloride to isophthalic acid chloride is determined in consideration of the solubility of the polymer, and there is no established theory. However, any chloride is 30 mol
It should be noted that the solubility of the synthesized polymer is extremely lowered when the content is less than 100%. Usually, it is preferable to synthesize at a ratio of 1/1.

[0035]

[Outside 5] (In the formula, R _{1 to} R ₁₆ are the same or different and each represents a hydrogen atom,
At least one group selected from the group consisting of a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkylidene group, -O- and -S- is shown. ) In the electrophotographic photosensitive member of the present invention, even a polymer having the same constitutional unit represented by the general formula (1),
It may be a copolymer composed of two or more different types of structural units represented by the general formula (1).

Further, a copolymer may be prepared with other general bisphenols such as bisphenol Z, bisphenol A, bisphenol C, and bisphenol AF in consideration of solubility during polymerization. However, in this case, the constitutional unit represented by the general formula (1) is 10 to 10 out of all the polymers.
It is preferably present at 0 mol%, more preferably 20
１００100 mol%.

The electrophotographic photoreceptor of the present invention has particularly excellent solvent crack resistance, mechanical strength, and electrical resistance characteristics against AC charging, and has good electrophotographic characteristics.

The polymer according to the present invention has a unit having rigidity in the constitutional unit, and the unit is partially vitrified at the time of forming the electrophotographic photosensitive member to improve the durability of the entire polymer coating. is there.

In addition, since the intramolecular density is increased by partially vitrifying the inside of the molecule and the amorphous part and the crystalline part are combined in the same molecule, the intramolecular stress generated during the formation of the coating film is also relaxed. Therefore, it is presumed that internal stress is maintained and cracks do not occur even if a chemical that causes solvent cracks enters. It is speculated that the mechanical strength becomes stronger due to the presence of the crystalline part.

Japanese Unexamined Patent Publication (Kokai) No. 6-214408 discloses a polycarbonate composed of bisphenol represented by the following formula (3).

[0041]

[Outside 6] Rigidity was too strong and vulnerable. On the other hand, by using the bisphenol represented by the general formula (2), it was possible to increase the degree of freedom in the molecule of the fluorene skeleton portion and suppress the brittleness while increasing the strength.

Further, it seems that the fluorene skeleton influences the improvement of durability against electric deterioration, but the details are unknown. Furthermore, it is considered that the arylate structure, which is an ester bond of an aryl group, is less likely to undergo molecular cleavage due to an electric current due to AC charging, as compared with a carbonate bond, and thus has particularly improved electric resistance. The reason for this has not been confirmed, but the carbonate bond has a large dipole moment because there are oxygen atoms on both sides of the carboxy group,
Presumed to be weak against electric energy.

Furthermore, it is presumed that the fluorene skeleton structurally tends to cause stacking with the triarylamine type charge transport material, and the photomemory can be improved.

The structure of the electrophotographic photosensitive member used in the present invention will be described below.

The electrophotographic photosensitive member according to the present invention may be a single layer type in which the photosensitive layer contains the charge transport material and the charge generating material in the same layer or a laminated type in which the charge transport layer and the charge generating layer are separated. It is good, but the laminated type is preferable in terms of electrophotographic characteristics.

The conductive support to be used may be any one having conductivity, and examples thereof include metals such as aluminum and stainless steel, metals provided with a conductive layer, paper, plastic, and the like, and the shape is a sheet or a cylinder. And so on.

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

An intermediate layer having an adhesive function is provided thereon. Examples of the material for the intermediate layer include polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane and polyether urethane. These are applied by dissolving in an appropriate solvent.
The thickness of the intermediate layer is 0.05 to 5 μm, preferably 0.3 to
1 μm is suitable.

The charge generation layer is formed on the intermediate layer.
Examples of the charge generating substance used in the present invention include selenium-tellurium, pyrylium, thiapyrylium dyes, phthalocyanines, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments. To be In the case of the function-separated type, the charge generation layer includes a homogenizer, ultrasonic dispersion, ball mill, vibrating ball mill, together with the binder resin and solvent in an amount of 0.3 to 4 times the amount of the charge generation material.
It is well formed by a method such as a sand mill, an attritor, a roll mill, and a liquid collision type high speed disperser, and the dispersion is applied and dried to form. The thickness of the charge generation layer is 5 μm or less, preferably 0.1 to 2 μm.

The charge transport layer is mainly formed by coating and drying a paint in which a charge transport material and the binder resin of the present invention are dissolved in a solvent. Examples of charge transport materials used include triarylamine compounds, hydrazone compounds,
Examples thereof 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, applied and dried to form a charge transport layer. The thickness of the charge transport layer is 5 to 40 μm, preferably 15 to 30
μm is suitable.

FIG. 1 shows a schematic configuration of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention.

In FIG. 1, 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 of the primary charging means 3 is uniformly charged with a positive or negative predetermined potential, and then image exposure light 4 from an image exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. Thus, an electrostatic latent image is sequentially formed on the peripheral surface of the photoconductor 1.

The formed electrostatic latent image is then transferred to developing means 5
The toner-developed image developed by the toner image is transferred from a paper supply unit (not shown) between the photoconductor 1 and the transfer unit 6 in synchronization with the rotation of the photoconductor 1 and fed to a transfer material 7 fed therefrom. The image is sequentially transferred by the transfer unit 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 to be printed out of the apparatus as a copy.

After the transfer of the image, the surface of the photoreceptor 1 is cleaned by removing the untransferred toner by the cleaning means 9, and is further cleaned with a pre-exposure light 10 from a 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, the pre-exposure is not necessarily required.

In the present invention, among the constituent elements such as the electrophotographic photosensitive member 1, the primary charging means 3, the developing means 5 and the cleaning means 9, a plurality of components are integrally combined as a process cartridge, The process cartridge may be detachably attached to the main body of the 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 photoconductor 1 to form a cartridge, and the cartridge can be attached to and detached from the apparatus body by using a guide unit such as a rail 12 of the apparatus body. It can be the process cartridge 11.

When the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is reflected or 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.

On the other hand, when used as a facsimile printer, the image exposure light 4 becomes exposure light for printing received data. FIG. 2 is a block diagram showing an example of this case.

The controller 14 controls the image reading section 13 and the printer 22. The entire controller 14 is controlled by the CPU 20. The read data from the image reading unit 13 is transmitted to the partner station through the transmission circuit 16. The data received from the partner station is sent to the printer 22 through the receiving circuit 15. Predetermined image data is stored in the image memory. The printer controller 21 controls the printer 22. 17 is a telephone.

The image received from the line 18 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 15 and then decoded by the CPU 20 to be sequentially stored in the image memory 19. Is done. When the image of at least one page is stored in the memory 19, the CPU 20 performs image recording of the page. The CPU 20 reads out the image information of one page from the image memory 19, and Sends out image information. The printer controller 21 is
When receiving one page of image information from the CPU 20, the printer 22 is controlled to record image information of the page. The CPU 20 is receiving the next page during recording by the printer 22.

In this manner, the reception and recording of the image are performed.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in laser beam printers, C
RT printer, LED printer, liquid crystal printer,
It can be widely used in electrophotographic application fields such as laser plate making.

[0064]

EXAMPLES Examples will be described below. In the examples, “parts” indicates “parts by weight”. [Example 1] An aluminum cylinder having a diameter of 30 mm 254 mm was used as a support, and a coating material composed of the following materials was applied to the support by a dipping method and heat-cured at 140 ° C for 30 minutes to form a conductive layer of 15 µm. .

Conductive pigment: 10 parts of barium sulfate treated with SnO ₂ coating Pigment for resistance control: 2 parts of titanium oxide Binder resin: 6 parts of phenol resin Leveling material: 0.001 part of silicone oil 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 onto the above by a dipping method to form an intermediate layer of 0.5 μm. Layers were formed.

Next, the diffraction angles 2θ ± 0.2 ° in the X-ray diffraction spectrum of CuKα are 9.0 °, 14.2 °, 2
Oxytitanium phthalocyanine (TiOPc) 4 parts having strong peaks at 3.9 ° and 27.1 °, polyvinyl butyral (trade name: S-REC BM2, manufactured by Sekisui Chemical Co., Ltd.)
After dispersing 2 parts and 60 parts of cyclohexanone in a sand mill using φ1 mm glass beads for 4 hours, 100 parts of ethyl acetate was added to prepare a dispersion liquid for a charge generation layer. This was applied by a dipping method to form a 0.3 μm charge generation layer.

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

[0069]

[Outside 7] 1 part of amine compound of the following structural formula

[0070]

[Outside 8] And 10 parts of the polymer described in Condition 1 of Table 2 were dissolved in a mixed solvent of 30 parts of monochlorobenzene and 70 parts of dichloromethane.

This polymer was prepared by dissolving the biphenol (0.003 mol) and bisphenol Z necessary to prepare the structural unit example 1 in sodium hydroxide (0.8 g), tetramethylammonium chloride (1 g) and 100 ml of water. Pour into a 1 liter mixer and add 1,2-
Dichloroethane (30 ml) and terephthalic acid chloride (0.005 mol) and isophthalic acid chloride (0.05 mol)
(05 mol) was added with stirring and 1
High speed stirring for 0 minutes. After being left for 2 hours, a 1,2-dichloroethane solution was recovered, and a large amount of hexane was added thereto to recover it as a polymer. It should be noted that, after the collection, the product was washed with water, washed with methanol, dissolved in chloroform, and purified by dropping methanol. The final yield was 68%.

This coating material was applied by the dipping method at 120 ° C. for 2
It was dried for an hour to form a 25 μm charge transport layer.

Next, evaluation will be described.

The apparatus is 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 produced electrophotographic photosensitive member was subjected to paper passing durability (HH durability) at 28 ° C. and 90% RH using this apparatus. The sequence was an intermittent mode in which the print was stopped once for each print.

When the toner ran out, the toner was replenished and the image was durable until a problem occurred in the image.

Further, the tape was abraded for 15 minutes using a Taber abrasion tester using a polishing tape, and the weight loss at that time was measured.

Further, 3000 L is applied to a part of the electrophotographic photosensitive member.
The light potential was measured after illuminating the white fluorescent lamp for 20 minutes with a white fluorescent lamp for 4 minutes, and measuring the light potential before the light was applied to determine the photomemory value.

Further, regarding the solvent cracking property, finger grease was adhered to the surface and left for 48 hours, and the presence or absence of solvent cracks was observed by observing with a 100 times optical microscope. Was designated as x.

The results are shown in Table 3.

[0080]

[Outside 9] The molecular weight was measured by gel permeation chromatography.

[Examples 2 to 10] Except that the binder resins used in the charge transport layer were those of conditions 2 to 10 in Table 2.
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1. Table 3 shows the results.

[0082]

[Outside 10]

[Comparative Examples 1 to 5] An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the binder resin used in the charge transport layer was selected from conditions 1 to 5 shown in Table 4. The results are shown in Table 5.

[0084]

[Outside 11]

[0085]

[Outside 12]

[0086]

EFFECTS OF THE INVENTION According to the present invention, it has excellent resistance to solvent cracks without impairing mechanical strength, has high mechanical strength, and has good electric resistance characteristics against discharge by direct charging. It has become possible to provide an electrophotographic photosensitive member suitable for direct charging that is easy to perform, and a process cartridge and an electrophotographic apparatus having the photosensitive member.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having a process cartridge having an electrophotographic photosensitive member of the present invention.

FIG. 2 is a diagram showing an example of a block diagram of a facsimile having the electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor of this invention 2 axis 3 Primary charging means 4 Image exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Image fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Rail 13 Image reading section 14 Controller 15 Receiving circuit 16 transmitting circuit 17 telephone 18 line 19 image memory 20 CPU 21 printer controller 22 printer

Claims (3)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the photoreceptor has the following general formula (1): (In the formula, R _{1 to} R ₁₇ are the same or different and each represents a hydrogen atom,
At least one group selected from the group consisting of a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkylidene group, -O- and -S- is shown. ) An electrophotographic photoreceptor comprising a polymer having a structural unit represented by 2. An electrophotographic photosensitive member according to claim 1, and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means, which are integrally supported and detachably mountable to the main body of the electrophotographic apparatus. Process cartridge characterized by. 3. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an image exposing unit, a developing unit and a transfer unit.