JPH1039532A - Electrophotographic photoreceptor, process cartridge and electrophotographic apparatus - Google Patents

Abstract

(57) [Abstract] (with correction) [PROBLEMS] To provide an electrophotographic photoreceptor having excellent solvent cracking resistance and mechanical strength, good electric resistance and little photo memory. SOLUTION: The electrophotographic photoreceptor whose surface layer contains a polyarylate resin obtained from a divalent carboxylic acid component represented by the formula (1) or (2) and a dihydric phenol component, and the electrophotographic photoreceptor Process cartridge and electrophotographic apparatus having the same. (In the formula, R _{1 to} R ₁₆ and R _{21 to} R ₃₆ represent a hydrogen atom, a halogen atom or an alkyl group.)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 are (1) that it can be charged to an appropriate potential in a dark place, (2) that the potential is less dissipated in a dark place, and (3) And (3) quickly dissipating the charge by light irradiation.

[0003] Conventionally, selenium,
Inorganic photoreceptors having a photosensitive layer mainly containing an inorganic photoconductive compound such as zinc oxide and cadmium sulfide 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. 851 describes a photoreceptor having a charge transporting layer containing triallylpyrazolin, and US Pat. No. 3,871,880 discloses a photogenerating layer comprising a derivative of perylene pigment and 3
Photoreceptors comprising a charge transport layer comprising a condensate of propylene and formaldehyde are known.

Further, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound.
JP-A Nos. 2754 and 56-167759 disclose substances exhibiting high sensitivity in the visible region, and JP-A-57-19576 and JP-A-61-22.
No. 8453 discloses a compound having 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 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, 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.

Particularly, in the case of an electrophotographic photoreceptor that is used repeatedly, an external electric or mechanical force such as corona or direct charging, image exposure, toner development, transfer step and surface cleaning is directly applied to the electrophotographic photoreceptor surface. For,
Durability against them is also required.

Specifically, electrical deterioration due to ozone and nitrogen oxides during charging, mechanical deterioration in which the surface is worn or scratched due to discharge during charging, and rubbing of the cleaning member, and electrical deterioration Durability 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.

[0011] Unlike an inorganic photoreceptor, an organic photoreceptor, which is often soft in material, is inferior in durability against mechanical deterioration and is particularly demanded to improve durability.

Various attempts have been made to satisfy the durability characteristics 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 the following problems cannot be solved. It has such problems.

(1) It has poor solubility and shows good solubility only in a part of halogenated aliphatic hydrocarbons such as dichloromethane and 1,2-dichloroethane. In addition, since these solvents have a low boiling point, they have low solubility. When a photoreceptor is manufactured using a coating solution prepared with the above solvent, the coated surface is likely to be whitened. It also takes time to control the solid content of the coating liquid.

(2) Solvents other than halogenated aliphatic hydrocarbons are partially soluble in tetrahydrafuran, dioxane, cyclohexanone or a mixed solvent thereof, but the solution gels in a few days. Inferior aging,
It is not suitable for photoconductor production.

(3) Further, even if the above formulas (1) and (2) are improved, solvent cracks are liable to occur in the polycarbonate resin having bisphenol A as a skeleton.

(4) In addition, in the case of a conventional polycarbonate resin, the coating formed of the resin does not have lubricity, so that the photosensitive member is easily damaged, and the cleaning setting for reducing the abrasion amount of the electrophotographic photosensitive member is not sufficient. In some cases, an image defect such as toner fusion occurs, or cleaning failure occurs due to early deterioration of the cleaning blade.

For the solution stability mentioned in the above (1) and (2), use of a polycarbonate Z resin having a bulky cyclohexylene group as a structural unit of the polymer, or copolymerization with bisphenol Z or bisphenol C, etc. Has been solved by

Solvent cracks can also be solved by using a silicone-modified polycarbonate or an ether-modified polycarbonate, as disclosed in JP-A-6-51544 and JP-A-6-75415. . However, compared to conventional polycarbonate resins, these modified polycarbonates have a structure that has flexibility against internal stress in the polymer in order to prevent solvent cracks, and as a result, the mechanical There was a disadvantage that the strength was reduced.

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

This is a method in which a roller-shaped charging member made of a conductive rubber or the like is brought into direct contact with an electrophotographic photosensitive member to apply an electric charge. The scorotron generates a significantly smaller amount of ozone than a scorotron or the like. While 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 this charging method has improved the stability during charging, the amount of discharge on the surface of the electrophotographic photosensitive member is greatly increased due to the superposition of AC, so that the amount of scraping of the electrophotographic photosensitive member increases. A new drawback has arisen, requiring not only mechanical strength but also electrical strength.

[0024]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of having a conventional polycarbonate resin as a surface layer, to have excellent solvent crack resistance without impairing mechanical strength, and An object of the present invention is to provide an electrophotographic photoreceptor which has good electric resistance due to direct charging, has less photo memory, is easy to manufacture, and a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor.

[0025]

That is, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photosensitive member has the following formula (1) or (2):
An electrophotographic photoreceptor comprising a polyarylate resin obtained from a divalent carboxylic acid component and a dihydric phenol component represented by the formula:

[0026]

Embedded image (In the formula, R _{1 to} R ₁₆ represent a hydrogen atom, a halogen atom or an alkyl group which may be substituted.)

[0027]

Embedded image (In the formula, R _{21 to} R ₃₆ represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group.)

[0028]

DETAILED DESCRIPTION OF THE INVENTION In the above formulas (1) and (2), halogen atoms include fluorine, chlorine and bromine atoms, and alkyl groups include methyl, ethyl and propyl. Examples of the substituent which the alkyl group may have include the above-described halogen atoms and alkyl groups.

Specific examples of the structural units represented by the above formulas (1) and (2) are shown in Tables 1 and 2, but are not limited thereto.

[0030]

[Table 1]

[0031]

[Table 2]

Preferred examples of the structural unit represented by the formula (1) include structural unit examples 1-1 and 1-2, and the structural unit example 1-1 is particularly preferable.

Preferred examples of the structural unit represented by the formula (2) include structural unit examples 1-1 and 1-2, and the structural unit example 1-1 is particularly preferable.

The polymer used in the present invention is obtained by performing interfacial polymerization by stirring a dicarboxylic acid or a chloride thereof represented by the formula (1) or (2) with bisphenol in a solvent / water system under an alkali. Can be synthesized by

The ratio between terephthalic acid and isophthalic acid is determined in consideration of the solubility of the polymer, and is not established. However, one dicarboxylic acid component is generally 70 m
Care must be taken when the amount exceeds ol%, since the solubility of the synthesized polymer is extremely reduced.

Further, as the dicarboxylic acid component, 3-te
Polymerization can also be performed using a compound having a substituent such as rt-butyl isophthalic acid.

The bisphenol used in the present invention is represented by the following formula (3).

[0038]

Embedded image (Wherein, X represents a single bond, —O—, —S—, —SO—, an alkylene group, a cycloalkylene group or a siloxane group which may be substituted, and R _{41 to} R ₄₈ represent a hydrogen atom, a halogen atom Represents an alkyl group or an aryl group which may be substituted) In the above formula (3), examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom, and examples of the alkyl group include a methyl group, an ethyl group and a propyl group. Groups, etc., as the alkylene group, a methylene group, an ethylene group, an i-propylene group, etc., as the cycloalkylene group, a pentylene group, a hexylene group, an octylene group, etc., and as the aryl group, a phenyl group, Examples include a naphthyl group and an anthryl group, and examples of the siloxane group include a disiloxane group and a trisiloxane group. And
Examples of the substituent which these may have include the above-described halogen atom, alkyl group and aryl group.

In the electrophotographic photoreceptor of the present invention, even if the bisphenol component is the same polymer as represented by the formula (3), two or more different types of constitutions represented by the formula (3) may be used. It may be a copolymer composed of units.

The electrophotographic photoreceptor of the present invention containing a polymer obtained from the divalent carboxylic acid component represented by the formulas (1) and (2) and the dihydric phenol component is particularly resistant to solvent cracking and mechanical strength. , Low photo memory characteristics, and electric resistance characteristics in AC charging, and good electrophotographic characteristics.

The polymer having a divalent carboxylic acid component represented by the formulas (1) and (2) contains a unit having rigidity in the structural unit, and the unit is formed when the electrophotographic photosensitive member is formed. By partially vitrifying, the durability of the entire polymer film is increased.

Further, the intramolecular density is increased by the partial vitrification inside the molecule, and since the amorphous portion and the crystalline portion are combined in the same molecule, the intramolecular stress generated at the time of forming the coating film can be reduced. It is presumed that even if a chemical causing a solvent crack enters, the internal stress is maintained and no crack occurs.

It is presumed that the mechanical strength is enhanced by the presence of the amorphous portion.

Regarding the electric resistance characteristics, the molecular cleavage due to the electrical degradation has no active protons in the central skeleton, and the arylate structure, which is an ester bond of an aryl group, is more resistant to the current due to AC charging than the carbonate bond. It is considered that the electric resistance was improved. Although the reason for this has not been confirmed, it is assumed that the carbonate bond has a large dipole moment due to oxygen atoms on both sides of the carboxy group and is weak against electric energy.

Hereinafter, the configuration of the electrophotographic photosensitive member used in the present invention will be described.

The electrophotographic photoreceptor of the present invention may be a single layer type in which the photosensitive layer contains a charge transport material and a charge generation material in the same layer, or a laminated type in which the charge transport layer and the charge generation layer are separated. Although good, the laminated type is preferable in terms of electrophotographic characteristics.

The conductive substrate to be used may be any one having conductivity, and may be a metal such as aluminum or stainless steel, or a metal provided with a conductive layer, paper, plastic, or the like. Is mentioned.

When an image input such as LBP is a laser beam, a conductive layer may be provided for the purpose of preventing interference fringes due to scattering or covering a scratch 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
４０40 μm is preferable, and more preferably 10-30 μm
It is.

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 preferably from 0.05 to 5 μm, more preferably from 0.3 to 1 μm.

The charge generation layer is formed on the intermediate layer.
Examples of the charge generation material used in the present invention include selenium-tellurium, pyrylium, thiapyrylium dyes, phthalocyanine, anthantrone, dibenzapyrene quinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments. Can be In the case of the function separation type, the charge generation layer is obtained by mixing the charge generation material 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 Disperse well by a method such as a high-speed disperser, apply the dispersion,
It is formed by 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 containing a polymer used in the present invention are dissolved in a solvent. Examples of the charge transport material used include a triarylamine compound, a hydrazone compound, a stilbene compound, a pyrazoline compound, an oxazole compound, a triallylmethane compound, and a thiazole compound.

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 preferably from 5 to 40 μm, more preferably from 15 to 30 μm.

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 in a direction of an arrow at a predetermined peripheral speed. The photoreceptor 1 rotates during the rotation process.
The peripheral surface is uniformly charged with a predetermined positive or negative potential by the primary charging means 3, and then receives image exposure light 4 from an image exposure means (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 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 by 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, a plurality of components such as the above-described electrophotographic photosensitive member 1, primary charging means 3, developing means 5 and cleaning means 9 are integrally connected as a process cartridge. This 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. Process cartridge 1
It can be 1.

When the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is reflected and transmitted from the original, or the original is read by a sensor and converted into a 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 unit 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. 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
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 way, image reception and recording are performed.

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,
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. The middle part in the examples indicates parts by weight.

Example 1 An aluminum cylinder having a diameter of 30 mm and 254 mm was used as a support, and a coating composed of the following materials was applied on the support by a dip coating method, and was heat-cured at 140 ° C. for 30 minutes and then 15 μm. Was formed.

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 obtained 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. Was formed.

Next, oxytitanium phthalocyanine (TiOPc) having strong peaks at Bragg angles 2θ ± 0.2 ° of 9.0 °, 14.2 °, 23.9 ° and 27.1 ° in CuKα characteristic X-ray diffraction. ) 4 parts and 2 parts of polyvinyl butyral (trade name: Eslec BM2, manufactured by Sekisui Chemical) and 60 parts of cyclohexanone were dispersed for 4 hours by a sand mill using φ1 mm glass beads, and then 100 parts of ethyl acetate was added to form a charge generating layer. A dispersion was prepared.
This was applied by a dip coating method to form a 0.3 μm charge generation layer.

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

[0071]

Embedded image 1 part of amine compound of the following structural formula

[0072]

Embedded image And Example No. 3 in Table 3. 10 parts of the polymer shown in 1 were dissolved in a mixed solvent of 30 parts of monochlorobenzene and 70 parts of dichloromethane.

This polymer was synthesized according to the following procedure.

Bisphenol C (0.003 mol) and bisphenol A (0.003 mol) are dissolved in sodium hydroxide (0.8 g), tetramethylammonium chloride (1 g) and 100 ml of water, and are introduced into a 1 liter mixer. To this, 1,2-dichloroethane (30 m
A solution prepared by dissolving Compound Example 1-1 (0.003 mol), terephthalic acid chloride (0.0015 mol) and isophthalic acid chloride (0.0015 mol) in l) was added with stirring, and the mixture was stirred at high speed for 10 minutes. After leaving for 2 hours,
A 1,2-dichloroethane solution was recovered, and a large amount of hexane was added thereto to recover a polymer. After the recovery, a water-washed, methanol-washed, chloroform-dissolved and purified step by dropwise addition of methanol was used. The final yield was 72%.

This paint is applied by a dip coating method,
It was dried at 120 ° C. for 2 hours to form a 25 μm charge transport layer.

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

Further, 3000 L of a part of the electrophotographic photosensitive member is used.
ux, exposed to the light of a white fluorescent lamp for 20 minutes, allowed to stand for 15 minutes, measured the bright portion potential, measured how much the bright portion potential had dropped before applying the light, and determined the photo memory value.

Further, regarding the solvent cracking property, sebum was adhered to the surface and allowed to stand for 48 hours, and the presence or absence of solvent cracks was observed by microscopic observation.

Table 4 shows the results.

[0082]

[Table 3] The molecular weight was measured by gel permeation chromatography.

[Examples 2 to 10] Example Nos. In Table 3 were used as binder resins for the charge transport layer. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that those having 2 to 10 were used. Table 4 shows the results.

[0084]

[Table 4]

[Examples 11 to 20] In Example 5, the binder resin of the charge transport layer was prepared as shown in Example 5 of Table 5. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the toners of Examples 11 to 20 were used. Table 6 shows the results.

[0086]

[Table 5]

[0087]

[Table 6] The molecular weight was measured by gel permeation chromatography.

[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 of the charge transport layer used was one of the conditions 1 to 5 shown in Table 7. Table 8 shows the results.

[0089]

[Table 7]

[0090]

[Table 8]

[0091]

The electrophotographic photoreceptor of the present invention has excellent solvent crack resistance without impairing the mechanical strength, has high mechanical strength, and has good electric resistance against discharge due to direct charging. It has become possible to provide an electrophotographic photosensitive member suitable for direct charging, which has less photo memory and is easy to manufacture, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

[Brief description of the 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 illustrating 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 (8)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photoreceptor comprises a divalent carboxylic acid component and a dihydric phenol component represented by the following formula (1). An electrophotographic photosensitive member containing the obtained polyarylate resin. Embedded image (In the formula, R _{1 to} R ₁₆ represent a hydrogen atom, a halogen atom or an alkyl group which may be substituted.) 2. The electrophotographic photosensitive member according to claim 1, wherein the divalent carboxylic acid component is a mixture of the divalent carboxylic acid component of the formula (1) and another carboxylic acid component. 3. The electrophotographic photoreceptor according to claim 2, wherein the other divalent carboxylic acid component is at least one selected from terephthalic acid and isophthalic acid. 4. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photosensitive member comprises a divalent carboxylic acid component and a dihydric phenol component represented by the following formula (2). An electrophotographic photosensitive member containing the obtained polyarylate resin. Embedded image (In the formula, R _{21 to} R ₃₆ represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group.) 5. The electrophotographic photosensitive member according to claim 4, wherein the divalent carboxylic acid component is a mixture of the divalent carboxylic acid component of the formula (2) and another carboxylic acid component. 6. The electrophotographic photosensitive member according to claim 5, wherein the other divalent carboxylic acid component is at least one selected from terephthalic acid and isophthalic acid. 7. The electrophotographic photoreceptor according to claim 1, wherein:
A process cartridge which integrally supports at least one unit selected from the group consisting of a charging unit, a developing unit, and a cleaning unit, and is detachable from an electrophotographic apparatus main body. 8. The electrophotographic photoreceptor according to claim 1, wherein
An electrophotographic apparatus comprising a charging unit, an image exposing unit, a developing unit, and a transferring unit.