JP2000227667A - Electrophotographic photoreceptor, process cartridge and electrophotographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the electrophotographic photoreceptor having stable characteristics in repeated uses and high mechanical strength and high abrasion resistance and the process cartridge having this. SOLUTION: The electrophotographic photoreceptor is provided on a conductive substrate with a photosensitive layer containing a resin having at least repeating units of a polyarylate resin having a fluorene structure represented by formula I in which each of R1 and R2 is a 1-3C alkyl group or an aryl group; and each of R3 and R4 is an H atom or same as R1 and R2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photoreceptor,
More particularly, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer containing a specific bisphenol polyarylate resin, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member is one of typical image holding members. 2. Description of the Related Art In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high-quality images. The core photoreceptor includes inorganic materials typified by selenium, cadmium sulfide, and zinc oxide.In recent years, however, from the viewpoints of non-pollution, high productivity, ease of material design and future potential, etc. Organic materials are being actively developed.

[0003] These electrophotographic photoreceptors naturally have electrical, mechanical,
Further, various characteristics such as optical characteristics are required. In particular,
In the case of a photoreceptor that is used repeatedly, electrical and mechanical forces such as charging, exposure, development, transfer, and cleaning are repeatedly applied directly or indirectly.

In an organic photoreceptor, an organic photoconductive material is usually dissolved or dispersed in a binder resin to form a coating film and used. The coating film is formed by dissolving or dispersing the organic photoconductive material and the binder resin in a solvent, and then coating and drying. As the binder resin, materials such as vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride and copolymers thereof, polycarbonate, polyester, polyarylate, polysulfone, phenoxy resin, epoxy resin, and silicone resin are used. I have.

[0005] These organic photoreceptors are excellent in mass productivity and are relatively inexpensive to produce. However, when a conventionally used resin is used for the photoreceptor, an image defect due to the generation of solvent cracks is caused. Evils may occur,
Improvement in solvent crack resistance is desired. Also,
The low molecular charge transport material reduces the inherent mechanical strength of the binder resin, which may lead to deterioration of the photoreceptor due to abrasion deterioration, scratches, cracks, etc. There was room.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having stable characteristics in repeated use, achieving high mechanical strength, and having high abrasion resistance. An object of the present invention is to provide a process cartridge and an electrophotographic apparatus.

[0007]

According to the present invention, in an electrophotographic photosensitive member having a photosensitive layer on a conductive support, a resin for forming the photosensitive layer is at least a fluorene represented by the following general formula (1). Provided are an electrophotographic photosensitive member containing a structural unit of a polyarylate resin having a structure, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

[0008]

Embedded image

In the formula, R ¹ and R ² are an alkyl group or an aryl group having 1 to 3 carbon atoms, R ³ and R ⁴ are a hydrogen atom and 1 carbon atom.
3 to 3 alkyl groups or aryl groups. Here, the alkyl group represents a methyl group, an ethyl group, a propyl group, or the like,
The aryl group represents a phenyl group or naphthyl.

[0010]

Embodiments of the present invention will be described below in detail.

A polyarylate resin having a fluorene having a substituent represented by the general formula (2) (R ¹ and R ^{2 in} the general formula (1) are methyl groups and R ³ and R ⁴ are hydrogen) is a charge transporting resin. It has excellent compatibility with the material, and more effectively prevents cracks.

[0012]

Embedded image

Further, as shown in the general formulas (3) and (4), by copolymerizing with a bisphenol having another structure, it is possible to improve the strength of the resin and the solubility of the resin in a solvent. In particular, in the polyarylate resin represented by the general formula (4), R ¹⁵ and R ¹⁶ are both methyl groups, R ¹⁷ and R ¹⁸ are both hydrogen, and R ¹⁹ and R ²⁰ are both methyl groups. A system in which a polyarylate resin having a fluorene structure represented by the general formula (2) is copolymerized can exhibit more wear strength.

[0014] Further, there is a production by a dip coating method with high productivity, which is one of the characteristics of the organic photoreceptor. Can be copolymerized with polyarylate as shown in the general formulas (3) and (4) or blended with a polyarylate resin or a polycarbonate resin having another structure, thereby improving the productivity. Can also be provided.

By using a fluorene-containing polyarylate resin for the photoreceptor, the effect of preventing cracks could be improved. Although the mechanism of the effect in the present invention has not been sufficiently elucidated, the materials used for the charge transporting material are mainly low molecular substances having a large number of aromatic rings,
It is presumed that it is effective to introduce more aromatic rings into the resin so that they are dispersed in the resin and retained by the resin.

Since the polyarylate having a fluorene structure used in the present invention has not only an aromatic ring at a phthalic acid site but also many aromatic rings at a fluorene site, the compatibility of the charge transfer material is improved and the effect of preventing cracks is obtained. It is considered that the stress relaxation when the charge transfer material is added to the resin is effectively working by appropriately restricting the polymer chains or the arrangement between the polymer chains by the fluorene moiety. In addition, by copolymerizing with polyarylate of other structure that has excellent mechanical strength, the resin itself is given abrasion resistance, and the synergistic effect with the improvement of compatibility with the charge transport material described above, as a photoreceptor It is considered that the durability of the steel has been improved.

The polyallylate resin of the general formula (1) preferably has a molecular weight of Mw = 10000 to 200,000, and has a molecular weight of 50,000 to 15,000 in view of strength, productivity and the like.
0 is particularly preferred.

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

[0019]

[Table 1]

[0020]

[Table 2]

The structural unit represented by the general formula (3) is represented as a copolymer of the general formulas (1) and (5). −
It is represented as a copolymer of 1) to (1-12) and specific structural unit examples (5-1) to (5-6) of the following general formula (5), and the combination is limited. Not done.

When the copolymerization ratio is expressed by the general formula (1) / general formula (3) = 95/5 to 5/95, the effect of each characteristic can be obtained. For more expression, the ratio is preferably 80/20 to 20/80. The molecular weight is Mw = 10000-2000
00 is preferable, and particularly preferably 50,000 to 150,000.

Next, specific examples of the structural unit represented by the general formula (5) will be shown, but the present invention is not limited to this structure.

[0024]

[Table 3]

Next, the polyarylate represented by the general formula (1) of the present invention can be used in a mixture with the polycarbonate represented by the general formula (6). Productivity and solution stability are improved.
The mixing ratio is represented by the general formula (1) / general formula (6) = 5/9
It is possible to be 5 to 95/5, and in order to exhibit the effect efficiently, 20/80 to 80/20 is preferable.

The molecular weight of the formula (6) is not particularly limited, but is preferably Mv = 20,000 to 80,000.
Specific examples of the structural unit represented by the general formula (6) are shown below. The combination in structure and mixing is not limited.

[0027]

[Table 4]

The polyarylate compound used in the present invention is
It is synthesized by an ordinary method. As an example, a synthesis example of the copolymer represented by the general formula (2) / the structural unit example (5-2) is shown below.

A bisphenol monomer constituting the general formula (2) / the structural unit example (5-2) (= 3/7) was added to and dissolved in a 10% aqueous sodium hydroxide solution. Further, trimethylbenzylammonium chloride was added as a polymerization catalyst, followed by stirring. Separately, an equal mixture of terephthalic acid chloride / isophthalic acid chloride was dissolved in dichloromethane. This dichloromethane solution was added to the previously prepared aqueous sodium hydroxide solution with stirring to initiate polymerization.

The polymerization was stirred for 3 hours while maintaining the reaction temperature at 25 ° C. or lower. Thereafter, the reaction was terminated by adding acetic acid, and the washing with water was repeated until the aqueous phase became neutral. After washing, the polymer was dropped into methanol with stirring to precipitate the polymer. Further, the polymer was dried under vacuum to obtain the compound of the present invention.

Hereinafter, the structure of the electrophotographic photosensitive member of the present invention will be described.

In the electrophotographic photoreceptor of the present invention, the photosensitive layer contains a single layer in which the charge transport material and the charge generating material are contained in the same layer, and contains the charge transport layer and the charge generating material containing the charge transport material. The present invention is applied to any of the stacked type having a charge generation layer.

The binder resin and the solvent for forming the photosensitive layer of the present invention are not limited in the photosensitive layer to be used.
A layer used by dissolving and dispersing a material (for example, a charge generating material or a charge transporting material) for forming a photoreceptor in a binder resin, such as a charge generating layer, a charge transporting layer, and a protective layer in a laminated photoreceptor And a single-layer type is also possible.

As the charge generating material in the present invention, those generally known can be used.
Examples include pigments such as tellurium, pyrylium, metal phthalocyanine, metal-free phthalocyanine, anthantrone, dibenzopyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, and quinacdrine. These pigments were dispersed well using a homogenizer, an ultrasonic disperser, a ball mill, a vibration mill, a sand mill attritor, a roll mill, a liquid collision type high-speed disperser and the like together with a binder resin and a solvent in a weight of 0.3 to 4 times. Make it a dispersion. In the case of a laminated type photoreceptor, this liquid is applied and dried to obtain a charge generation layer. The thickness is preferably 5 μm or less, particularly preferably 0.1 to 2 μm.

As the charge transport material, those which are usually used can be used, for example, triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, thiazole compounds and the like. Is mentioned. These compounds are dissolved in a solvent together with a binder resin to form a solution.
In the case of a laminated photoreceptor, a charge transport layer is obtained by applying and drying this liquid. The thickness is preferably from 5 to 40 μm, particularly preferably from 15 to 30 μm.

When the photosensitive layer is of a single-layer type, the photosensitive layer is formed by applying a solution obtained by dispersing and dissolving the above-described charge generating material and charge transporting material in the above-described binder resin, followed by drying. be able to. The film thickness is 5 to 40 μm
It is particularly preferable that the thickness is 15 to 30 μm.

The protective layer can be obtained by applying and drying a solution obtained by dissolving the above-mentioned binder resin in a solvent. If necessary, electrophotographic photoreceptor materials,
A conductive material for controlling the resistance value, a lubricating material for providing lubricity, and the like can also be added. In the case of a photoreceptor having no protective layer, an antioxidant or a lubricant may be used for the surface layer as necessary.

In the present invention, an intermediate layer having an adhesive function and a charge barrier function can be provided between the support and the photosensitive layer or between the conductive layer and the photosensitive layer, if necessary. As a material of the intermediate layer, for example, polyamide,
Examples thereof include polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane. These are dissolved in a solvent, applied and dried. The thickness of the intermediate layer is preferably 0.05 to 5 μm, particularly preferably 0.2 to 1 μm. Further, the ratio (weight ratio) between the solvent and the material of the intermediate layer is preferably 1 / 0.5 to 1/2.

The method of applying the photoreceptor is not limited, and it can be used by a commonly known means such as a dip coating method, a spray coating method, and a bar coating method.

FIG. 1 shows a schematic configuration of an electrophotographic apparatus using a process cartridge having an 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 at a predetermined positive or negative potential by the primary charging means 3, and then, the time-series electricity of target image information output from exposure means (not shown) such as slit exposure or laser beam scanning exposure. The exposure light 4 which has been enhanced and modulated according to the digital image signal is received. Thus, an electrostatic latent image corresponding to the target image information 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 image thus developed 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 to a transfer material 7 fed and fed. Then, the toner image formed and carried on the surface of the photoconductor 1 is sequentially transferred by the transfer unit 6.

The transfer material 7 to which the toner image has been transferred is separated from the surface of the photoreceptor, introduced into the image fixing means 8 and subjected to image fixing to be printed out as an image formed product (print, copy) outside the apparatus. You.

The surface of the photoreceptor 1 after image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 9, and is further subjected to 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, of the above-mentioned components 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 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, and is detachably attached to 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 exposure light 4 is reflected light or transmitted light from the original, or the original is read by a sensor, converted into a signal, and a laser beam is emitted in accordance with the signal. Beam scanning, LED
Light emitted by driving the 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,
It can be widely used in electrophotographic applications such as CRT printers, LED printers, liquid crystal printers, and laser plate making.

[0048]

The present invention will be described in more detail with reference to the following examples. In the examples, "parts" represents parts by weight.

Example 1 A coating composed of the following materials was applied on an aluminum cylinder of 30 mmφ × 357 mm by a dip coating method, and was thermally cured at 140 ° C. for 30 minutes to obtain a film having a thickness of 15 μm. A conductive layer 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 2/8 20 Department

Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol was applied onto the conductive layer by dip coating. By drying, an intermediate layer having a thickness of 0.5 μm was formed.

Next, in the CuKα characteristic X-ray diffraction, the black angles (2θ ± 0.2 °) of 9.0 °, 14.2 °, 2 °
4 parts of oxytitanium phthalocyanine having strong peaks at 3.9 ° and 27.1 °, 2 parts of polyvinyl butyral (trade name: Eslec BM2, manufactured by Sekisui Chemical) and 60 parts of cyclohexanone were converted to 4 parts by a sand mill using 1 mmφ glass beads. After dispersion for an hour, 100 parts of ethyl acetate was added to prepare a dispersion for a charge generation layer. By applying this dispersion on the intermediate layer by a dip coating method and drying,
A charge generation layer having a thickness of 0.1 μm was formed.

Next, 7 parts of an amine compound having the following structural formula

[0054]

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

[0055]

Embedded image 10 parts of the compound (Mw = 75000) represented by Structural Unit Example (1-1) as a binder resin was dissolved in a mixed solvent of 50 parts of monochlorobenzene / 30 parts of dichloromethane to obtain a coating solution for a charge transport layer. The coating solution was applied by a dip coating method, and dried at 120 ° C. for 1 hour to form a 27 μm-thick charge transport layer.

Next, the evaluation will be described. The apparatus used was a copying machine GP210 (contact charging system) manufactured by Canon Inc. First, the initial potential was measured. Dark section potential Vd = -70
At 0 V, the light portion potential Vl was set to -200 V. The A4 size plain paper was stopped once for each copy, but 10,000 copies were made in the intermittent mode, and then the abrasion of the photoconductor film thickness was measured.

Further, sebum was adhered to the surface of the new photoreceptor and left for 72 hours, and the presence or absence of solvent cracks was observed under a microscope (100 times). Observation was performed at 10 observation points, and "O" indicates that there were no cracks at all observation points, "Δ" indicates that only one observation point occurred, and 2 or more observation points "X" indicates the occurrence
And

Example 2 Structural Unit Example (1-10) (Mw = 78000) as Binder Resin for Charge Transport Layer
A photoconductor was prepared in the same manner as in Example 1, except that

(Example 3) Structural unit example (1-12) as binder resin for charge transport layer (Mw = 70000)
A photoconductor was prepared in the same manner as in Example 1, except that

Example 4 Structural unit example (1-1) / (5-1) = 50/5 as binder resin for charge transport layer
A photoconductor was prepared by the same way as that of Example 1 except that the copolymer was 0 (Mw = 80000).

Example 5 Structural unit example (1-1) / (5-2) = 50/5 as binder resin for charge transport layer
A photoconductor was prepared by the same way as that of Example 1 except that the copolymer was 0 (Mw = 80000).

(Example 6) Structural unit example (1-1) / (5-2) = 70/3 as binder resin for charge transport layer
0 (Mw = 80000) and 5 parts of the polyarylate resin of Structural Unit Example (5-2),
A photoconductor was produced in the same manner as in Example 1.

Example 7 Structural Unit Example (1-1) / (5-2) = 30/7 as Binder Resin for Charge Transport Layer
Example 1 except that 5 parts of a copolymer (Mw = 80000) of No. 0 and 5 parts of a polycarbonate Z (Iupilon Z200 manufactured by Mitsubishi Gas Chemical) represented by Structural Unit Example (6-5) were used.
A photoreceptor was prepared in the same manner as described above.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that the polyarylate (Mw = 70000) shown in Structural Unit Example (5-1) was used as the binder resin for the charge transport layer. .

Comparative Example 2 As a binder resin for a charge transport layer, a polyarylate of the following structural formula (7) (Mw = 7)
0000), and a photoconductor was prepared in the same manner as in Example 1.

[0066]

Embedded image

Table 5 shows the results.

[0068]

[Table 5]

As shown in Table 5, the photoreceptor of the present invention
It exhibited mechanical durability (wear resistance) and excellent solvent crack resistance. Also, comparing the unsubstituted fluorene type polymer shown in Comparative Example 2 with the substituted type of the present invention,
Superior in abrasion resistance and solvent crack resistance. In other words, it is presumed that the introduction of the substituent appropriately restricts the steric configuration between the polymer chains and the polymer, resulting in an appropriate configuration. Furthermore,
The arrangement increases the affinity with the organic photoconductive material in the polymer, improves the abrasion resistance of the photosensitive layer,
It is assumed that the occurrence of stress in the entanglement between the polymer chains and the polymer that induces the solvent crack is reduced. The superiority of the polyarylate resin shown in the present invention was shown.

[0070]

According to the present invention, an electrophotographic photoreceptor having improved abrasion resistance and improved solvent crack resistance in repeated use by using a polyarylate resin having a specific fluorene structure, It has become possible to provide a process cartridge and an electrophotographic apparatus having a body.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2 axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Rail

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor ▲ Akira Yoshi ▼ 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H068 AA13 AA21 BB26 BB27 FA03 FA27 FA30

Claims (8)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the resin for forming the photosensitive layer comprises:
An electrophotographic photoreceptor comprising at least a structural unit of a polyarylate resin represented by the following general formula (1). Embedded image (Wherein, R ¹ and R ² represent an alkyl group or an aryl group having 1 to 3 carbon atoms, R ³ and R ⁴ represent a hydrogen atom, an alkyl group or an aryl group having 1 to 3 carbon atoms) 2. The electrophotographic photosensitive member according to claim 1, wherein the resin for forming the photosensitive layer is at least a polyarylate resin represented by the following general formula (2). Embedded image 3. The electrophotographic photoreceptor according to claim 1, wherein the resin for forming the photosensitive layer is at least a polyarylate copolymer having a structural unit represented by the following general formula (3). Embedded image (Wherein, R ⁵ and R ⁶ represent an alkyl group or an aryl group having 1 to 3 carbon atoms, R ⁷ and R ⁸ represent a hydrogen atom, an alkyl group or an aryl group having 1 to 3 carbon atoms. R ^{9 to} R ¹² Is a hydrogen atom,
C1-C5 alkyl group, aryl group, C1-C5
Represents an alkoxy group or a halogen atom. X ¹ represents a single bond, —CR ¹³ R ¹⁴ —. R ¹³ and R ^{14 each} represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkylidene group formed by bonding R ¹³ and R ¹⁴ , and m and n each represent a positive integer) 4. The electrophotographic photosensitive member according to claim 2, wherein the resin for forming the photosensitive layer is at least a polyarylate copolymer having a structural unit represented by the following general formula (4). Embedded image (Wherein, R ^{15 to} R ¹⁸ represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group, an alkoxy group having 1 to 5 carbon atoms or a halogen atom. X ² represents a single bond, —CR ^{1 9} R ²⁰
Indicates-. R ¹⁹ and R ^{20 each} represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkylidene group formed by combining R ¹⁹ and R ²⁰ , and s and t each represent a positive integer) 5. The electrophotographic photoreceptor according to claim 1, wherein the resin constituting the photosensitive layer contains at least a structural unit of a polyarylate resin represented by the following general formula (5). . Embedded image (Wherein, R ^{21 to} R ²⁴ represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group, an alkoxy group having 1 to 5 carbon atoms or a halogen atom. X ³ is a single bond, —CR ^{2 5} R ²⁶
Indicates-. R ²⁵ and R ²⁶ represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkylidene group formed by combining R ²⁵ and R ²⁶ ) 6. The electrophotographic photoconductor according to claim 1, wherein the resin constituting the photosensitive layer contains at least a structural unit of a polycarbonate resin represented by the following general formula (6). Embedded image (Wherein, R ^{27 to} R ³⁰ represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group, an alkoxy group having 1 to 5 carbon atoms or a halogen atom. X ⁴ represents a single bond, —CR ^{3 1} R ³²
Indicates-. R ³¹ and R ^{32 each} represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group or an alkylidene group formed by bonding R ³¹ and R ³² ) 7. A charging unit for charging the electrophotographic photosensitive member according to claim 1 to charge the electrophotographic photosensitive member.
Integrated with at least one unit selected from the group consisting of a developing unit for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner, and a cleaning unit for collecting residual toner on the photosensitive member after the transfer process And a process cartridge which is detachably mounted on the main body of the electrophotographic apparatus. 8. An electrophotographic photoreceptor according to claim 1, a charging means for charging the electrophotographic photoreceptor, and exposing the charged electrophotographic photoreceptor to form an electrostatic latent image. An electrophotographic apparatus comprising: an exposure unit; a developing unit that develops an electrophotographic photosensitive member on which an electrostatic latent image is formed with toner; and a transfer unit that heats and transfers a toner image on a transfer material.