JP2002296808A - Electrophotographic sensitive body, process cartridge and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic sensitive body which has an excellent electrophotographic characteristic and is excellently stabilized and a process cartridge and an electrophotographic device having the electrophotographic sensitive body thereof. SOLUTION: An electric charge transportation layer incorporates antioxidant, and a difference between the contact angle of an electric charge generating layer surface to demineralized water and that of an electric charge transportation layer surface to the demineralized water is set within 10 deg..

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, and an electrophotographic apparatus. More specifically, the present invention relates to an electrophotographic photosensitive member having good electrophotographic characteristics and excellent stability, and this electrophotographic photosensitive member. And a process cartridge having the same.

[0002]

2. Description of the Related Art In recent years, electrophotographic photosensitive members having various organic photoconductive compounds have been actively developed. For example, U.S. Pat. No. 3,838,851 discloses a photoreceptor having a charge transporting layer containing triarylpyrazoline, and U.S. Pat. No. 3,871,880 discloses a photogenerating layer comprising a perylene pigment derivative and a charge generating layer comprising 3-propylene and formaldehyde. A photoreceptor containing a charge transport layer comprising a condensate is described.

[0003] Organic photoconductive compounds have different wavelength ranges of sensitivity depending on the compound.
JP-A-2754 and JP-A-56-167759 disclose compounds having high sensitivity in the visible region.
Japanese Patent Application Laid-Open No. 1-228453 discloses a compound having high sensitivity in the infrared region. Among these compounds, those having sensitivity in the infrared region are used for laser beam printers (hereinafter abbreviated as LBP) and LED printers, and the demand for them is increasing.

On the other hand, as a charging means, a contact charging means for charging an electrophotographic photosensitive member by applying a voltage to a charging member arranged in contact with the electrophotographic photosensitive member is disclosed in Japanese Patent Application Laid-Open No. Sho.
These are disclosed in, for example, JP-A-7-17826 and JP-A-58-40566.

[0005] The contact charging means is compared with the corona charging means.
Ozone generation is extremely low. Also, while about 80% of the current that the corona charging means passes through the charger, the current flows through the shield and is wasted, whereas contact charging is very economical because there is no waste.

However, in the contact charging means,
Since the charging member is in contact with the electrophotographic photosensitive member, the electrophotographic photosensitive member requires higher mechanical strength. Further, for the purpose of improving the charging stability, it has been proposed to use a voltage obtained by superimposing an AC voltage on a DC voltage as an applied voltage (Japanese Patent Application Laid-Open No. 63-149668). Although the stability is improved, the amount of current flowing through the electrophotographic photosensitive member for superimposing an AC voltage is greatly increased. As a result, the amount of scraping of the electrophotographic photoreceptor increases, and a problem that fogging occurs in an image newly arises, and various means for improving not only mechanical strength but also electrical strength have been studied. .

However, if the amount of scraping of the charge transport layer of the electrophotographic photosensitive member is reduced due to the improvement of the mechanical and electrical durability characteristics, or if the amount of shaving is large to a large degree, the oxidized and deteriorated resin and When the surface deposits cannot be sufficiently removed, the resistance of the surface of the photoreceptor is reduced, and a phenomenon that the formed image becomes unclear as if flowing (hereinafter, referred to as image deletion) may occur.
This phenomenon occurs particularly remarkably when a contact charging unit using a voltage obtained by superimposing an AC voltage on a DC voltage is applied as an applied voltage, and more remarkably occurs when sufficiently moistened paper is used as a transfer material.

As a means for preventing image deletion, it is known to add an antioxidant to the charge transport layer. However, if the antioxidant is added, the adhesion to the charge generation layer is reduced. In order to keep the gap between the photoconductor and the electrophotographic photoreceptor constant, peeling of the edge occurs due to the pressing pressure of the sleeve rollers attached to both ends of the developing sleeve,
As a result, the discharge at the edges of the charging member and the electrophotographic photosensitive member increased, and as a result, fogging at the edge of the image became a problem. Further, a decrease in the adhesion between the charge generation layer and the charge transport layer also causes a decrease in carrier injection efficiency, and a problem of deterioration in initial sensitivity.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide an electrophotographic photosensitive member having good electrophotographic characteristics and excellent stability. An object of the present invention is to provide a process cartridge and an electrophotographic apparatus.

[0010]

According to the present invention, in an electrophotographic photoreceptor having a charge generating layer and a charge transporting layer on a support, the charge transporting layer contains an antioxidant and the surface of the charge generating layer. Wherein the difference between the contact angle of pure water and the contact angle of the surface of the charge transport layer with pure water is within 10 °, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

[0011]

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

The antioxidants used in the present invention include:
Hindered phenol antioxidants and phosphorus antioxidants are particularly preferred. These may be used alone, but it is particularly preferable to use a combination of a hindered phenol antioxidant and a phosphorus antioxidant.

If the content of the antioxidant is too small, the effect on image deletion becomes insufficient, and if the content is too large, not only deterioration of electrophotographic characteristics such as increase in residual potential but also pure water on the surface of the charge transport layer is caused. Is increased, and as a result, the adhesion to the charge generation layer is reduced. Therefore, it is necessary to select an appropriate amount. Specifically, it is preferably 0.01 to 30% by mass, and particularly preferably 0.1 to 20% by mass, based on the charge transport layer resin.

The charge generation material used in the present invention is preferably oxytitanium phthalocyanine from the viewpoint of high sensitivity, and has a Bragg angle (2θ ± 0.2 °) of 9.0 ° or 14.2 ° in X-ray diffraction of CuKα.゜, 23.9
Oxytitanium phthalocyanines with strong peaks at {and 27.1} are particularly preferred.

The oxytitanium phthalocyanine used in the present invention is represented by the following structural formula.

[0016]

Embedded image Here, X ₁ , X ₂ , X ₃ , and X ₄ represent Cl or Br, and n, m, l, and k are integers of 0 to 4.

As the binder resin for the charge generation layer, for example, polyvinyl butyral resin, polyester resin,
An acrylic resin, a phenoxy resin, a polycarbonate resin, a polyvinyl acetal resin, a polystyrene resin, a polyarylate resin and the like can be mentioned, and a polyvinyl butyral resin is preferable in terms of stability of the dispersion.

The dispersion solvent may be a mixed solvent of an organic solvent and water, but a hydrophilic organic solvent is preferable, for example, tetrahydrofuran, n-propyl ether, n-butyl ether, 1,4-dioxane and the like. Ether solvents, methanol, ethanol, propanol,
Examples thereof include alcohol solvents such as 2-methoxyethanol and ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone.

The amount of the solvent used and the composition of the mixture are such that 10 parts by weight of oxytitanium phthalocyanine and 10 parts by weight of organic solvent are used.
It is sufficient that the amount is not less than 0.05 part by mass and not more than 10 parts by mass, the amount of the binder resin is dissolved, and the composition of the liquid. In particular, 20 parts by weight of an organic solvent is used for 1 part by mass of oxytitanium phthalocyanine.
It is more preferably not less than 80 parts by mass, and more preferably not less than 0.1 part by mass and less than 1 part by mass of water. This dispersion may be used as it is as a coating solution for the charge generation layer, or may be used by mixing with another organic solvent.

The dispersion treatment is performed by using, for example, a dispersing medium such as glass beads, steel beads, or alumina balls, a milling machine such as a paint shaker, a sand mill, or a ball mill, a homogenizer, an ultrasonic disperser, or a high-pressure liquid collision disperser. This is the process to be performed.

Since the binder resin such as the polyvinyl butyral resin described above has a strong hydrophilicity, if the dispersion treatment is performed only with oxytitanium phthalocyanine having high water repellency and an organic solvent, the crystallinity is insufficiently developed. As a result, the contact angle with the pure water on the surface of the charge generation layer is reduced.

That is, even if the adhesion to the charge generation layer is reduced by adding an antioxidant to the charge transport layer to prevent image deletion, the dispersion solvent for the charge generation layer is mixed with an organic solvent and water. By increasing the contact angle of the surface of the charge generation layer with pure water by using a solvent, it is possible to form an interface with strong adhesion, and obtain an electrophotographic photoreceptor that is highly sensitive and does not cause edge fog. You can do it.

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

The support (also referred to as a substrate) to be used may be any one having conductivity, such as a metal such as aluminum and stainless steel, or a metal provided with a conductive layer, paper, and plastic.

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 conductive 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 to 40 μm, preferably 10 to 30 μm.

An intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. As the material of the intermediate layer, polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose,
Examples include 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 5 μm.
1 μm.

A charge generating layer is formed on the intermediate layer.
It is formed by applying and drying a dispersion obtained by subjecting the oxytitanium phthalocyanine to a dispersion treatment together with the binder resin and a dispersion solvent. The ratio of oxytitanium phthalocyanine to the polymer binder in the charge generation layer is from 10: 1 to 1: 5, preferably 5: 1, by mass ratio.
It is in the range of 1-1: 2. The thickness of the charge generation layer is 5 μm or less, preferably 0.05 to 1 μm.

The charge transport layer is formed by coating and drying a paint obtained by dissolving a charge transport material, a binder resin and the above-mentioned antioxidant 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. Also, as the binder resin, polyester resin, acrylic resin,
Examples thereof include a polyvinyl carbazole resin, a phenoxy resin, a polycarbonate resin, a polyvinyl butyral resin, a polystyrene resin, a polyvinyl acetate resin, a polysulfone resin, a polyarylate resin, vinylidene chloride, and an acrylonitrile copolymer resin. The thickness of the charge transport layer is 5 to 40 μm, preferably 10 to 30 μm.

The conductive layer, the intermediate layer, the charge generation layer, the charge transport layer, and the protective layer are formed by dip coating, spray coating, spinner coating, roller coating, wire coating, and blade coating. Law and the like, but are not limited thereto.

FIG. 1 shows a schematic configuration of an electrophotographic apparatus provided with 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, which is driven to rotate around an axis 2 at a predetermined peripheral speed in a direction indicated by an arrow. In the rotation process, the electrophotographic photosensitive member 1 is uniformly charged around the periphery thereof by the primary charging means 3 at a predetermined positive or negative potential, and then is supplied from exposure means (not shown) such as slit exposure or laser beam scanning exposure. The exposure light 4 is received. Thus, an electrostatic latent image is sequentially formed around the electrophotographic photosensitive member 1.

The formed electrostatic image is then developed
The toner-developed image is developed and transferred from a feeding unit (not shown) between the electrophotographic photosensitive member 1 and the transfer unit 6 in synchronization with the rotation of the electrophotographic photosensitive member 1 and fed. The material is sequentially transferred to the material 7 by the transfer means 6. The transfer material 7 having undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means 8 and subjected to image fixing, thereby being printed out as a copy outside the apparatus. The surface of the electrophotographic photoreceptor 1 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 9, and furthermore, a pre-exposure light 10 from a pre-exposure means (not shown).
Is used for repeated image formation. 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, the electrophotographic photosensitive member 1 and a plurality of constituent elements such as the primary charging means 3, developing means 5 and cleaning means 9 are integrally connected as a process cartridge. Alternatively, the process cartridge may be configured to be detachable from an electrophotographic apparatus body 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 with the electrophotographic photosensitive member 1 to form a cartridge, and is detachably attached to the apparatus main body using the guide means such as the rail 12 of the apparatus main body. Process cartridge 11. The exposure light 4 is
When the electrophotographic apparatus is a copying machine or a printer, reflected light or transmitted light from the original, or reading the original with a sensor and converting it into a signal, scanning the laser beam performed according to this signal, driving the LED array, and liquid crystal This is light emitted by driving a shutter array or the like. The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

[0034]

The present invention will be described below in more detail with reference to specific examples. In addition, "part" in an Example shows a mass part.

Example 1 An aluminum cylinder of 30φ × 254 mm was used as a support,
In addition, 50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resole type phenol resin, 30 parts of methoxypropanol, and 3 parts of methanol
0 parts and silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, weight average molecular weight 300
0) 0.002 parts were dispersed in a sand mill containing 1 mmφ glass beads for 2 hours to prepare a coating material for the conductive layer. This coating material was applied on a support by a dipping method and dried at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 20 μm.

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 placed on the conductive layer by a dipping method. And dried to a thickness of 0.5 μm
Was formed.

Next, 9.0 of the Bragg angle (2θ ± 0.2 °) in X-ray diffraction of CuKα as a charge generating material is used.
Using 10 parts of oxytitanium phthalocyanine having strong peaks at {, 14.2}, 23.9} and 27.1}, polyvinyl butyral (trade name: Eslek BX-
1, Sekisui Chemical Co., Ltd.) with cyclohexanone: water = 97:
166 dissolved in a mixed solvent of 3
Parts, a mixed solvent of cyclohexanone: water = 97: 3 in 15
After dispersing for 4 hours in a sand mill using 400 parts of 1 mmφ glass beads for 4 hours, 210 parts of a mixed solvent of cyclohexanone: water = 97: 3 and 260 parts of cyclohexanone were added to prepare a paint for a charge generation layer. did. This paint is applied on the intermediate layer by a dipping method,
For 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

Next, a drop-type contact angle meter (trade name: CA-
As a result of measuring the contact angle of the surface of the charge generation layer with pure water using an X-type (manufactured by Kyowa Interface Science Co., Ltd.), the contact angle was 91.0.
Was ゜.

Next, 9 parts of an amine compound having the following structural formula was used as a charge transport material:

[0040]

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

[0041]

Embedded image And polycarbonate resin (trade name: Iupilon Z-20)
0, manufactured by Mitsubishi Gas Chemical Company) and 10 parts of a hindered phenolic antioxidant represented by the following formula:

[0042]

Embedded image Was dissolved in a mixed solvent of 60 parts of monochlorobenzene / 40 parts of dichloromethane to prepare a paint for a charge transport layer. This paint was applied on the charge generation layer by an immersion method, and dried at 115 ° C. for 60 minutes to form a charge transport layer having a thickness of 25 μm.

Next, a drop-type contact angle meter (trade name: CA-
As a result of measuring the contact angle of the surface of the charge transport layer with pure water using an X-type (manufactured by Kyowa Interface Science Co., Ltd.), the contact angle was 95.0.
Was ゜.

Next, the evaluation will be described. The device is a Hewlett-Packard LBP "Laser Jet 4plus" having a contact charging roller as a primary charging member.
(Process speed: 71 mm / sec) modified (DC voltage: -700 V, AC voltage between peaks:
1.6 KV, frequency: 1 KHz). In the remodeling, the primary charging was changed from constant current control to constant voltage control.

Using the prepared electrophotographic photoreceptor, the initial light-area potential was measured in an environment of 23 ° C./50% RH using this apparatus, and then a paper passing durability test was performed in an environment of 28 ° C./90% RH. Was done. The image was A4 and a grid pattern with a printing rate of 4% was used. The sequence was an intermittent mode in which the printing was stopped once for each print. When the toner ran out, the toner was replenished, the image was repeatedly printed until edge fogging occurred, and the number of sheets when the problem occurred was recorded.

Next, using the above-mentioned remodeling device, the temperature was set to 33 ° C./9.
Paper with a moisture absorption of 10% in an environment of 5% RH (moisture absorption is Inf
MOISTRE made by raid Engineering
It was measured using XMX5000. ), The durability of 2,000 sheets of continuous paper passing was evaluated, and the image deletion was evaluated. The image was A4, an E character pattern having a printing rate of 4%. The evaluation was 2,000 for the initial period, 2,000 for the endurance of the 2,000 sheets, and 24 hours after standing for 24 hours after the end of the 2,000 images. △ indicates that the flow is occurring but the character can be identified, × indicates that the character cannot be identified, and XX indicates that the character has completely disappeared. Table 1 shows the results.

Example 2 The antioxidant was replaced by a phosphorus-based antioxidant of the following formula: 0.5
Department

[0048]

Embedded image An electrophotographic photoreceptor similar to that of Example 1 was prepared, except that the evaluation was made, and the evaluation was performed. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 91.0 °. After the photoreceptor was prepared, the contact angle of the charge transport layer surface to pure water was measured. As a result, the contact angle was 96.0 °. Table 1 shows the results.

Example 3 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 0.5 parts of the phosphorus-based antioxidant of Example 2 was added as an antioxidant and two kinds of antioxidants were combined. It was fabricated and evaluated. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 91.0 °. After the photoreceptor was prepared, the contact angle of the surface of the charge transport layer with respect to pure water was measured.
It was 0 °. Table 1 shows the results.

Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the mass of the antioxidant was changed to 0.1 part, and evaluated. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 91.0 °. After the photoreceptor was prepared, the contact angle of the surface of the charge transport layer with respect to pure water was measured. As a result, the contact angle was 93.0 °. Table 1 shows the results.

Comparative Example 1 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the mixed solvent of the coating material for the charge generation layer, cyclohexanone: water was dispersed and prepared with 100% of cyclohexanone. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 83.0 °. After the photoreceptor was prepared, the contact angle of the surface of the charge transport layer with respect to pure water was measured. As a result, the contact angle was 95.0.
Was ゜. Table 1 shows the results.

Comparative Example 2 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 2 except that the mixed solvent of the coating material for the charge generating layer, cyclohexanone: water was dispersed and prepared with 100% of cyclohexanone. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 83.0 °. After the photoreceptor was prepared, the contact angle of the surface of the charge transport layer with respect to pure water was measured. As a result, the contact angle was 96.0.
Was ゜. Table 1 shows the results.

Comparative Example 3 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 3, except that the mixed solvent of the paint for the charge generation layer, cyclohexanone: water was dispersed in 100% cyclohexanone and prepared. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 83.0 °. After the photoreceptor was prepared, the contact angle of the surface of the charge transport layer with respect to pure water was measured.
It was 0 °. Table 1 shows the results.

Comparative Example 4 An electrophotographic photosensitive member similar to that of Comparative Example 1 was prepared and evaluated except that no antioxidant was added. After forming the charge generation layer, the contact angle of the surface of the charge generation layer with respect to pure water was measured. As a result, the contact angle was 83.0 °. After the photoreceptor was prepared, the contact angle of the surface of the charge transport layer with respect to pure water was measured. As a result, the contact angle was 91.0 °. Table 1 shows the results.

[0055]

[Table 1]

[0056]

According to the present invention, the charge transport layer contains an antioxidant, and the difference between the contact angle of the charge generation layer surface with pure water and the contact angle of the charge transport layer surface with pure water is within 10 °. As a result, it has become possible to provide an electrophotographic photosensitive member having good electrophotographic characteristics and excellent stability, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

[Brief description of the drawings]

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

[Description of Signs] 1 electrophotographic photosensitive member 2 axis 3 primary charging means 4 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

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H068 AA16 AA19 AA28 BA12 BA39 EA12 EA14

Claims (9)

[Claims] 1. An electrophotographic photoreceptor having a charge generation layer and a charge transport layer on a support, wherein the charge transport layer contains an antioxidant, and the contact angle of the surface of the charge generation layer to pure water and the The difference in contact angle between the charge transport layer surface and pure water is 1
An electrophotographic photoreceptor characterized by being within 0 °. 2. The electrophotographic photoreceptor according to claim 1, wherein said antioxidant is at least one of a hindered phenol antioxidant and a phosphorus antioxidant. 3. The electrophotographic photoreceptor according to claim 1, wherein the content of the antioxidant is 0.01 to 30% by mass based on the resin contained in the charge transport layer. 4. The electrophotographic photoconductor according to claim 1, wherein the charge generation layer contains oxytitanium phthalocyanine. 5. The oxytitanium phthalocyanine has strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° at Bragg angles 2θ ± 0.2 ° in X-ray diffraction of CuKα. Item 6. The electrophotographic photosensitive member according to Item 4. 6. The electrophotographic photosensitive member according to claim 4, wherein the charge generation layer is a layer formed using a dispersion containing a binder resin, a mixed solvent of an organic solvent and water, and the oxytitanium phthalocyanine. . 7. The amount of the organic solvent used is 10 parts by mass or more and 160 parts by mass or less based on 1 part by mass of the oxytitanium phthalocyanine, and the amount of the water used is 1 part by mass of the oxytitanium phthalocyanine. And 0.
The electrophotographic photoreceptor according to claim 6, wherein the amount is from 05 parts by mass to 10 parts by mass. 8. An electrophotographic photosensitive member according to claim 1, and charging means for charging the electrophotographic photosensitive member.
At least one member selected from the group consisting of developing means for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner and cleaning means for collecting residual toner on the electrophotographic photosensitive member after the transfer step A process cartridge integrally supporting the means and being detachable from the main body of the electrophotographic apparatus. 9. An electrophotographic photosensitive member according to claim 1, a charging means for charging said electrophotographic photosensitive member, and forming an electrostatic latent image by exposing said charged electrophotographic photosensitive member to light. An electrophotographic apparatus, comprising: an exposure unit that develops the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner; and a transfer unit that heats and transfers a toner image on a transfer material.