JPH02132455A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance the charge holding performance of the photosensitive body and to eliminate the disturbance of images so as to stabilize the images by forming a protective layer of two layers of films consisting of carbon or essentially consisting of the carbon and forming the front side layer so as to have the specific resistivity smaller than the specific resistivity of the layer on the photoconductive layer side. CONSTITUTION:The org. photosensitive layer 47 is formed by dip coating, etc., on a conductive base 41 and the protective layer 44 consisting of the two layers which consist of the carbon or consist essentially of the carbon is formed on the layer 7. The front side of the layer 44 is formed to have the specific resistivity smaller by >=1 digits than the specific resistivity of the layer 47 side. The layer 44 is formed by putting the base formed with the layer 47 in, for example, a plasma CVD device, introducing NF3 and C2H4 into the device and forming the films by changing the film forming conditions. The generation of flaws is preferably decreased by forming the layer 44 on the front side to have the hardness higher by >=50% than the hardness on the layer 47 side.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an electrophotographic photoreceptor having a surface protective layer on an organic photosensitive layer.

``Prior Art'' Conventionally, photoreceptors used in electrophotography include those in which an inorganic photoconductive material such as selenium is dispersed in a binder on a conductive support, and polyurethane resin (PoIJ N-vinyl Rubazole). Generally known are those using organic photoconductive materials such as trinitrofluoreon or azo pigments, and those using amorphous silicon materials.

The "electrophotographic method" referred to here generally refers to a photoconductive photoreceptor that is first charged in a dark place by, for example, corona discharge, and then exposed to image light to selectively dissipate the charge only in the exposed areas. An electrostatic latent image is obtained, and this latent image area is developed and visualized using electrodetecting fine particles (toner) composed of colorants such as dyes and pigments and binders such as polymeric substances to form an image. It is one of the image forming methods.

The basic characteristics required of the photoreceptor in such electrophotography are (1) the ability to be charged to an appropriate potential in a dark place;

(2) Less charge dissipation in the dark.

(3) The charge can be quickly dissipated by light irradiation.

Examples include.

In addition to these basic characteristics, each of the above-mentioned photoreceptors has excellent features and disadvantages in practical use, but among them, in recent years, manufacturing costs have been low. The development of organic photoreceptors is remarkable because they cause less environmental pollution and allow relatively flexible photoreceptor design.

In general, an organic photoreceptor is one in which a charge transport material is dispersed or dissolved in a binder resin and coated on a conductive support, allowing charge retention in a single layer. A single-layer type with the function of charge generation and charge transport, a charge generation layer (CGL) with the function of charge generation, a charge transport layer (CTL) with the function of holding the charged charge and transporting the charge injected from the CGL, and A functionally separated type is known in which a layer having a function of blocking charge injection from the support or preventing light reflection from the support is laminated as necessary.

These organic photoreceptors have excellent characteristics as mentioned above, but because they are organic materials, their surface hardness is low and they are susceptible to mechanical damage from developers, cleaning materials, etc. during actual use in the copying process. It also has the inherent drawback that it is prone to wear and scratches due to load.

This abrasion of the photosensitive layer causes a decrease in the charging potential, and local scratches cause streak-like abnormal images to appear on copies, both of which are important problems that affect the life of the photoreceptor.

In order to overcome these drawbacks, a method has been proposed in which a protective layer is provided on the surface of the organic photosensitive layer to improve its durability against mechanical loads received inside and outside the copying machine. For example, a method of providing an organic film on the surface of a photosensitive layer (Japanese Patent Publication No. 38-1
5446). Method of providing inorganic oxide (Special Publication 1977-
14517). Method of laminating an insulating layer after providing an adhesive layer (Japanese Patent Publication No. 43-27591). Or plasma CV
A-Si layer, a-St:N by D method, photo-CVD method, etc.
:H layer, a-St:O:HJii, etc. method (Japanese Patent Application Laid-Open No. 57-179859, JP-A No. 59-58437)
) etc. are disclosed.

Furthermore, in recent years, the application of high-hardness diamond-like carbon films to protective layers has become active. For example, a protective layer made of amorphous carbon or hard carbon is provided on a photosensitive layer (Japanese Unexamined Patent Publication No. 6
0-249155). A diamond-like carbon protective layer provided on the outermost surface (Japanese Patent Application Laid-Open No. 61255352),
A high-hardness insulating layer mainly composed of carbon is formed on a photosensitive layer (JP-A-61-264355), or a plasma organic polymer film containing at least nitrogen atoms, alkali metal atoms, etc. on an organic photosensitive layer. 2 (Japanese Unexamined Patent Publication No. 63-97961-4), a glow discharge containing at least chalcogen atoms, group II atoms, group II atoms, group V atoms, etc., is formed on the organic photosensitive layer. A protective film made of amorphous hydrocarbon film (Japanese Unexamined Patent Application Publication No. 1983-1999)
-220166 to 9).

In all of these proposals, carbon or a highly hard thin film mainly composed of carbon (i-carbon) is produced on the surface of an organic photosensitive layer by an ion process (sputtering, plasma CD, glow discharge method, photo-CVD method, etc.). It belongs to what is collectively referred to as a diamond-like carbon film or a diamond-like carbon film.

``Problem to be solved by the invention'' Through this method, it became possible to increase the surface hardness of the organic photosensitive layer, and as a result, it was possible to create a photoreceptor that could withstand tens of thousands of copies. Furthermore, streak-like scratches appeared on the surface of the seven photoconductors that continued to output images, causing abnormal images.

In order to solve this problem, the present invention provides first and second carbon or carbon-based coatings in a protective layer consisting of an organic photosensitive layer and carbon or a carbon-based coating. By providing the specific resistance of the first layer close to , which is at least one order of magnitude larger than the specific resistance of the second layer, the first layer acts as a charge-retaining layer, resulting in electrophotography having excellent long-term mechanical durability. The purpose is to provide a photoreceptor. Furthermore, the hardness of the second layer, which is the outermost layer, is increased by 50% or more compared to the hardness of the first layer.

In order to achieve the above object, the present invention comprises laminating an organic photosensitive layer, an intermediate layer if necessary, and a protective layer on the outermost surface in this order on a conductive support. In the electrophotographic photoreceptor having the above structure, the protective layer includes first and second carbon or carbon-based coatings, and the specific resistance of the second coating is 1 compared to the specific resistance of the first coating. This is an order of magnitude smaller.

Generally, scratches that occur on the surface of the photoreceptor affect the image,
The more rough the photoreceptor surface is, the lower the image quality will be. This is because the charge existing on the photoreceptor surface is affected by the surface shape.
This is thought to be caused by disordered charge distribution. Therefore, the charge forming the latent image may be held not on the surface of the photoreceptor, but inside the photoreceptor so that even if a scratch occurs, it will not be affected by the shape of the scratch. This is the charge-retaining layer, and in the present invention, the charge-retaining layer is composed of a first carbon or a film mainly composed of carbon near the photosensitive layer. Here, since the second coating must quickly conduct the charge generated on the surface of the photoconductor to the charge retention layer, the specific resistance of the second coating is the same as that of the first coating.
It is necessary to make the resistivity smaller by one or more orders of magnitude, preferably by two or more orders of magnitude, than the specific resistance of the film.

Furthermore, the hardness of the second coating is 5% compared to the hardness of the first coating.
It is made harder by 0% or more.

In order to minimize the occurrence of scratches, carbon or a film mainly composed of carbon is effective because it provides a hard film, but if it is too hard, the photosensitive layer is soft because it is an organic material, so it is not very hard. If the film is too thick, it will not fit well with the film, and if the film is several micrometers thick, cracks will occur. Therefore, the first layer is made relatively soft and provided as a buffer layer between the soft film and the hard film, and the second layer is made 50% or more harder than the first layer to improve wear resistance. It is.

"Structure of the Invention" As the conductive support used in the present invention, a conductor or an insulator treated for conductivity is used.

For example, AI, Ag. A thin film formed of a metal such as Au or a conductive material such as In203+SnOz. An example is paper that has been subjected to conductive treatment.

Further, the shape of the conductive support is not particularly limited, and a plate, drum, or belt shape may be used as required.

As described above, the organic photosensitive layer provided directly or via an undercoat layer on the conductive support includes a single layer type and a functionally separated type.

Examples of single-layer photosensitive layers include dye-sensitized zinc oxide and titanium oxide. Photoconductive powder such as zinc sulfide, selenium powder, amorphous silicon powder, squirt salt pigment, phthalocyanine pigment, azulenium salt pigment, azo pigment, etc. are optionally added to the binder resin and/or the electron donor described below. Examples include those formed by coating together with a polycarbonate compound, and those using a composition in which an electron-donating compound is added to a eutectic complex formed from a pyrylium dye and a bisphenol A polycarbonate. As the binder resin, the same resin as that used in the functionally separated photosensitive layer described later can be used. The thickness of this single-layer type photosensitive layer is suitably 5 to 30 μm.

On the other hand, in the functionally separated photosensitive layer, a charge generating layer (CGL) for generating and separating latent image charges by image exposure is formed by binding inorganic photoconductive powders such as crystalline selenium and arsenic selenide, or organic dyes and pigments. Dispersed or dissolved in agent resin is used.

As an organic dye and pigment as a charge generating substance, for example, C.I. Pigment Blue-25 [Color Index (CR)]
21180). CI Pigment Red 4HCI2
1200), Sea Eye Acid Red 52 (CI
45100), CI Basic Red 3 (CI
45210), and cyanide pigments having a porphyrin skeleton, azulenium salt pigments, and squalic salt pigments. Azo pigments having a carbazole skeleton
-95033), azo pigments having a styrylstilbene skeleton (described in JP-A-53-138229), azo pigments having a triphenylamine skeleton (described in JP-A-53132547), dibenzothiophine Azo pigments having a skeleton (described in JP-A-54-21728), azo pigments having an oxadiazole skeleton (described in JP-A-54-12742), azo pigments having a fluorenone skeleton (described in JP-A-54-12742), -22834), azo pigments with a bisstilbene skeleton (described in JP-A-54-17733), azo pigments with a distyryloxadiazole skeleton (described in JP-A-54-21),
29), an azo pigment having a distyrylcarbazole skeleton (described in JP-A-54-2129),
In addition, C.I. Phthalocyanine pigments such as Pigment Blue-16 (Cl 74100), Sea Eye Pad Brown 5 (CI
73410), Sea Eye Baddie (CI 730)
30) 9 grade indigo pigment, Argo Scarlet B
(manufactured by Panolette), Indus Thread Scarlet R
(manufactured by Bayer AG) and other berylene pigments can be used.

These charge generating substances may be used alone or in combination of two or more.

The amount of the binder resin is 0 to 100 parts by weight of the charge generating substance.
It is appropriate to use 100 parts by weight, preferably O~5
It is 0 parts by weight.

Binding resins used in combination with these organic dyes and pigments include polyimide, polyurethane, polyester, and epoxy resin. Condensation resins such as polycarbonate and polyether, as well as polystyrene and polyacrylate polymethacrylate. Adhesive and insulating resins such as polymers and copolymers such as poly-N-vinyl Rubazole, polyvinyl butyral, styrene-butadiene copolymer, and styrene-acrylonitrile copolymer can be mentioned.

The charge generation layer contains a charge generation substance, along with a binder resin if necessary, tetrahydrofuran, cyclohexanone,
It can be formed by dispersing with a ball mill, attritor, sand mill, etc. using a solvent such as dioxane or dichloroethane, and diluting the dispersion liquid appropriately and applying it. Application can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer is suitably about 0.01 to 5 .mu.m, preferably 0.1 to 2 .mu.m.

When particles of crystalline selenium or arsenic selenide alloy are used as the charge-generating substance, they are used in combination with an electron-donating binder and/or an electron-donating organic compound. Examples of such electron-donating substances include polyvinylcarbazole and its derivatives (for example, those having halogens such as chlorine and bromine, and substituents such as methyl and amino groups in the carbazole skeleton), polyvinylpyrene, oxadiazole, pyrazoline, and hydrazone. , diarylmethane, α-phenylstilbene,
Nitrogen-containing compounds such as triphenylamine compounds and diarylmethane compounds are included, and polyvinyl rubberazole and its derivatives are particularly preferred. Alternatively, a mixture of these substances may be used. Even when used in combination, it is preferable to add other electron-donating organic compounds to polyvinyl Rubazole and its derivatives. The content of this type of inorganic charge generating substance is 30 to 90% by weight of the entire layer.
is appropriate. Further, when an inorganic charge generating material is used, the thickness of the charge generating layer is suitably 0.2 to 5 .mu.m.

The charge transport layer (CTL) is a layer whose purpose is to hold electric charges and to move the electric charges generated and separated in the charge generation layer by exposure and combine them with the held electric charges. In order to achieve the purpose of retaining charged charges, it is required to have high electrical resistance, and in order to achieve the purpose of obtaining a high surface potential from the retained charges, it is necessary to have a low dielectric constant and good charge mobility. required.

A charge transport layer that satisfies these requirements is composed of a charge transport substance and a binder resin used as necessary. That is, the charge transport layer can be formed by dissolving or dispersing the above-mentioned substances in a suitable solvent and applying and drying the solution.

Charge transport materials include hole transport materials and electron transport materials.

Examples of the hole transport substance include poly N-vinylcarbazole and its derivatives, poly γ-carbazolylethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene. Polyvinylphenanthrene. Oxazole derivatives, oxadiazole derivatives, imidazole derivatives. Triphenylamine derivative 9-(p-diethylaminostyryl)anthracene. 1.1-bis-(4-dibenzylaminophenyl)
Propane, styryl anthracene. Examples include electron-donating substances such as styrylpyrazoline, phenylhydrazones, and α-phenylstilbene derivatives.

Examples of electron transport substances include chloranil, promanil, tetracyanoethylene, and tetracyanoquinone dimethane. 2.4.7- 1-linitro-9-fluorenone, 2,4,5.7-tetranitro-9-fluorenone, 2,4.5.7-tetranitroxanthone, 2,4.
8- }linitrothioxanthone, 2,6.8- }linitro-4H-indeno (1.2-b) thiophene-4one, L3,7- }linitrodibenzothiophenone 5,5-dioxide, etc. Examples include receptive substances.

These charge transport materials may be used alone or in combination of two or more.

Binder resins that may be used as necessary include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. ．． Polyvinyl acetate. Polyvinylidene chloride, polyacrylate resin, phenoxy resin. Polycarbonate cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenolic resin. Examples include thermoplastic or thermosetting resins such as alkyd resins.

As the solvent, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. are used.

The appropriate thickness of the charge transport layer is about 5 to 100 μm.

Furthermore, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as plasticizers for general resins, such as dibutyl phthalate and dioctyl phthalate, can be used as they are, and the appropriate amount to be used is about 0 to 30% by weight based on the binder resin. Dimethyl silicone oil is used as a leveling agent. Silicone oils such as methylphenyl silicone oil are used, and the amount used is 0 to 100% relative to the binder resin.
Approximately 1% by weight is appropriate.

These CGL and CTL are placed on the support from the support side.
L and CTL may be stacked in this order, or CTL and CGL may be stacked in this order.

Carbon or a coating mainly composed of carbon and a method for producing the same will be described below.

FIG. 2 shows an example of a device that can be used in the present invention. In the drawing, the reaction volume R9r of the plasma CvD device
(1) is separated by a loading/unloading preliminary chamber (7") and a gate valve (9). In the gas system (30), carrier gas is supplied from (31) and reactive gas is supplied from (32).
), the additive gas is supplied from (33), the etching gas for the reaction vessel is supplied from (34), the valve (28), and the flow meter (
29) and introduced into the reaction system (50) through a nozzle (25).

The reaction system (50) has a frame structure (2) (having a square or hexagonal frame structure when viewed from the electrode side) as shown in FIGS. A hood (8), (8) is provided in the lower opening to cover this opening.
A pair of first and second electrodes (3), (3') having the same shape and arranged on the hood (8), (8') are made of aluminum metal mesh. The reactive gas is emitted downward from the nozzle (25).The third electrode has an organic photosensitive layer provided on an aluminum cylindrical support, and in terms of direct current, the photosensitive layer is an insulating material. , add the second alternating voltage here,
In terms of alternating current, it was made substantially conductive and a bias was applied. The formation surface (1゛) on this base (1) is connected to a pair of electrodes (3)
, (3°). Substrate (1-1), (1-2),...(
1n), that is, (1) has the formation surfaces (1'-1), (1''-
2)...(1'-n), and an alternating voltage of 1 to 500 Kl{z to which a second alternating voltage and a negative DC bias are applied is applied. In this case, the DC bias is actively generated by the self-bias accumulated by the second AC power supply in a capacitor (not shown) installed between the second AC voltage source and the third electrode (substrate) and the DC power supply. Either DC bias may be applied. The reactive gas that has become plasma in the glow discharge due to the first high-frequency alternating voltage is uniformly dispersed in the reaction space (60), and this plasma is (2),
(8) and (8') to prevent it from being emitted in a plasma state into the external space (6) outside of this to prevent it from adhering to the inner wall of the reaction vessel. In addition, the plasma potential in the reaction space was made homogeneous.

Furthermore, in order to make the potential distribution in the plasma reaction space more equal, alternating voltages of two different frequencies can be applied to the power supply system (40). The first alternating voltage is 1~
It is a high frequency of 100 MHz, and a pair of two power supplies (
Matching transformer (16-1) from (15-1) and (15-2). This leads to (16-2). The phase in this matching transformer is adjusted by a phase adjuster, so that the signals can be supplied with a difference of 180° or 0.6° from each other.

The transformer has a symmetrical or in-phase output, and one end (4) and the other end (4') of the transformer are respectively connected to a pair of first and second electrodes (3) and (3''). Further, the midpoint (5) on the output side of the transformer is held at ground level, and a second alternating electric field (17) of 1 to 500 KHz is applied.The output is passed through a capacitor (not shown) to the substrate (1- 1').(1-2'), ...(1-n
'), i.e. connected to the third electrode of (1) or the holder (2) electrically connected thereto.

Thus, plasma (60) is generated in the reaction space.

The exhaust system (20) exhausts unnecessary gas through a pressure regulating valve (21), a turbo molecular pump (22), and a rotary pump (23).

These reactive gases are present in the reaction space (60) at 0.001
~1. Otorr, and this frame structure (2) has a rectangular or hexagonal shape, for example, in the case of a rectangular shape, as shown in FIG.
The width was 75 cm, the depth was 75 cm, and the height was 50 cm as shown in the figure.

Then, a cylindrical substrate having a surface to be formed is placed in this (1-1).
+ (1-2) ... (1-n) ... As shown, here, 16 wires are arranged at equal intervals. Dummy base materials (1-0) and (1-n+1) are also provided inside the outer frame structure (2) to form a uniform electric field. In such a space, a high frequency of 1 to 100 MHz is applied at 0.5 to 5 KW (0.3 to 3 W/c per unit area).
A first high-frequency voltage is applied at a voltage of -10 to -600 V on the surface to be formed by applying an alternating current bias using a second alternating voltage. A film can be formed by sputtering a reactive gas accelerated by a self-bias voltage onto a substrate, resulting in a dense film.By controlling this negative self-bias voltage, the hardness of the film can be increased! This is one of the characteristics of the carbon film forming method used in the present invention.An example of the relationship between negative self-bias voltage and film hardness is shown in FIG.

Hydrogen or argon can be used as the carrier gas, hydrocarbons such as methane and ethylene, or carbide gases such as carbon fluoride can be used as the reactive gases, and nitrides such as nitrogen fluoride and ammonia can be used as the additive gases. As the etching gas for the reaction vessel, oxygen or a fluoride gas such as nitrogen fluoride or carbon fluoride can be used. When ethylene and nitrogen fluoride are introduced as reaction gases, for example, the diamond-like carbon film (also referred to as DLC) to which nitrogen and fluorine are added is used. A film can be formed.

The reactive gas is, for example, a mixed gas of ethylene and nitrogen fluoride, the ratio of which is NF. /C2H4 = 1/20 ~4
/1. By varying this ratio, transmittance and specific resistance can be controlled.

The temperature of the substrate is typically maintained at room temperature.

Typical characteristics of carbon or a coating mainly composed of carbon created by the above method are that it forms a c-c bond similar to that of diamond with an sp' orbital, and has a Vickers hardness of 10.
0 ~ 3000Kg/cm2, specific resistance (specific resistance) IX
IO7 to IXIO"ΩclI1, and an optical energy band (referred to as Eg) of 1.OeV or more,
Preferably 1.5-5. It has properties similar to and better than that of diamond, which is transparent in the infrared or visible region with a voltage of 5 eV.

Since the first carbon or carbon-based coating used in the present invention acts as a charge retention layer, the specific resistance is 101
0~10''Ωcm, preferably lQ12~IQIIΩc
m, film thickness is 300-5000 people, preferably 500-2
It is better to set it to 000 people. At the same time, in order to act as a buffer layer to prevent peeling and cracking of the film, the hardness should preferably be less than 500 kg/mm" in terms of Vickers hardness. Also, the second carbon or carbon-based film has no electric charge. In order to quickly conduct the charge to the first carbon or the coating mainly composed of carbon, which is the charge retention layer, the specific resistance is 109
~10I4ΩG, preferably 10th ~1012Ωcm,
The film thickness is 1000 to 10 μm, preferably 5000 to 10 μm.
It is preferable to set the thickness to 2 μm. If the hardness is too hard, peeling or cracking of the film will occur, so it is recommended to set the hardness to 1500 to 4000 kg/mm2 if the film thickness is about 1 μm, and 1000 to 1500 kg/mm if the film thickness is Sam or more. .

The present invention will be illustrated below with reference to Examples.

Example 1 This example shows an example in which carbon or a film containing carbon as a main component is prepared on a cylindrical organic photosensitive layer as shown in FIG.

? An organic photosensitive layer (47) according to the following formulation is formed on an aluminum cylindrical support (41) having the shape shown in Figure 1.
was produced.

Aluminum cylindrical support (outer diameter 40mmφ, length 2
50 mm) with the following composition ratio in a ball mill.
The film thickness after drying the undercoat layer forming liquid prepared by time-dispersion is approximately 2.
A subbing layer was formed by dipping to a thickness of μm.

[Subbing layer forming liquid]

TiO■ (Tie Bake manufactured by Ishihara Sangyo Co., Ltd.) 1 part by weight Polyamide resin (CM-8000 manufactured by Toray Industries, Inc.) 1 part by weight Methanol 25 parts by weight A charge generation layer coating solution having the following formulation was dip coated on this subbing layer, 12
The tube was dried at 0°C for 10 minutes to form a charge generation layer with a thickness of about 0.15 μm.

[Charge generation layer coating liquid]

Trisazo pigment having the following structure: 30 parts by weight Polyester resin (Vylon manufactured by Toyobo Co., Ltd.) 12 parts by weight cyclohexane 360 parts After dispersing the above mixture in a ball mill for 72 hours, 500 parts by weight of a mixed solvent of cyclohexane and methyl ethyl ketone in a 1:1 (weight ratio) Adjust the dilution in 1 part.

Next, a charge transport layer was provided on the charge generation layer by dip coating a charge transport layer coating solution having the following formulation so that the film thickness after drying was approximately 20 μm.

(Charge Transport Layer Coating Liquid) <'2's'> (Product name Panrai C1400: Teijin Kasei ■) Silicone oil 0.0002 parts by weight (Product name KF50: Shin-Etsu Silicone ■) Tetrahydrofuran 80 parts by weight After this The first layer is placed on the charge transport layer.
Carbon or a coating mainly composed of carbon was provided.

Using the apparatus shown in FIG. 2 and using the method described above, the flow rate of NFS was set to 5SCCM, the flow rate of CzHa was set to 803CCM, the reaction pressure was 0.05Torr, and the first alternating electric field frequency was 13.56.
M}Iz, its output 400 μm, second alternating electric field frequency 2
50KHz, voltage amplitude 100V, DC bias -5
At 0V, a first carbon or carbon-based coating having a transparent amorphous structure or crystal structure to infrared or visible light with a specific resistance IXIO" Ω mark is applied to the organic photoreceptor to a thickness of 0.1 μm. (Central part) The film formation rate was 500 persons/min, and the hardness was Vickers hardness 500 Kg/+n.
m'' optical energy band width had 2.4 eV.

Similarly, NF. The flow rate of 20SCCM%C
The flow rate of 2H4 was 803 CCM, and the reaction pressure was 0.05 Tor.
r, first alternating electric field frequency 13.56M2, output 400 second alternating electric field frequency 250KHz, voltage amplitude 400V, DC bias -200V. Or, for visible light, apply a second carbon having a translucent amorphous structure or crystal structure or a coating mainly composed of carbon to 0.5 μm.
m (center) was produced. The film forming rate was 400 persons/min, the hardness was 1800 Kg/mm" in Vickers hardness, and the optical energy band width was 1.8 eV.

-60°C →
As a result of 100 temperature cycles from room temperature to -60°C, the coating did not crack or peel off from the substrate.
Even in an actual copying machine, the protective film (44) will not crack or peel even if mechanical loads are applied locally by cleaning blades, separation claws, transfer paper, etc., and the size of the A4 size Even after copying 100,000 sheets of paper, no scratches were generated on the surface due to rubbing of the copy paper.

Figure 4 shows an example after further copying and reaching 300,000 copies. An example of initial copying is shown in (A), and the result after 300,000 copies were made is shown in (B). Almost no difference was observed between them.

After copying 300,000 copies, the surface of the photoconductor had some roughness that was not seen at the beginning, but no image disturbance occurred and a good quality image could be obtained. This allows the electrical charge to be maintained at or near the boundary between the first coating and the second coating, and even if the surface of the second coating becomes rough due to hundreds of thousands of copies, image distortion will not occur. It was confirmed that high-quality images could be obtained without the need for

Comparative Example 1 In this comparative example, a subbing layer, a charge generation layer, and a charge transport layer were formed on an aluminum cylindrical support in the same manner as in the example, and then the first carbon or carbon-based layer was formed on the aluminum cylindrical support. A photoreceptor with only a coating formed thereon is shown. For this photoreceptor, -6
As a result of 100 temperature cycles from 0"C to room temperature to -60°C, the coating did not crack or peel off from the substrate, and even in an actual copying machine, cleaning blades, separating claws, transfer paper, etc. Even when mechanical loads were applied locally, no cracks or peeling occurred, but after about 50,000 copies were made, roughness that was not seen at the beginning appeared on the surface of the photoreceptor. Image disturbance corresponding to the roughness occurred, making it impossible to obtain a good quality image.This is because electrical charges are retained on the surface of the first carbon layer or a coating mainly composed of carbon, which is the outermost layer. This shows that the image is influenced by the surface shape of the coating No. 1.

Comparative Example 2 This comparative example shows a photoreceptor in which a subbing layer, a charge generation layer and a charge transport layer were formed on an aluminum cylindrical support in the same manner as in the examples. Image distortion began to occur after 10,000 to 20,000 copies, and it became unusable after 30,000 copies. The surface of this photoreceptor was extremely rough after use.

"Effect" According to the present invention, in an electrophotographic photoreceptor having a structure in which an organic photoreceptor layer is laminated on a conductive support, an intermediate layer if necessary, and a protective layer on the outermost surface in this order, the protective layer is laminated on the first and second layers. It consists of a second carbon or a film mainly composed of carbon, and the resistivity of the second film is one order of magnitude smaller than that of the first film, so that the electric charge is transferred between the first film and the second film. It can be maintained at or near the boundary of the coating, and even if the surface of the second coating becomes rough due to mechanical stress, no image disturbance occurs and stable, high-quality images can be obtained over a long period of time.

In addition, since the first coating is made softer than the second coating, the adhesion between the first and second coatings and the charge transport layer is good, and the hardening of the second coating provides good wear resistance. We were able to fabricate a photoreceptor with high

[Brief explanation of the drawing]

FIG. 1 shows an example in which a cylindrical substrate of the present invention is coated with carbon or a film mainly composed of carbon. FIG. 2 shows an outline of the plasma CVD apparatus of the present invention. Figures 3 (A) and (B) show the plasma C shown in Figure 2.
The arrangement method of the base in the VD device is shown. FIG. 4 shows an example of electrostatic copying using an organic photoreceptor drum made using the method of the present invention. FIG. 5 shows an example of the relationship between DC bias and film hardness in the method of the present invention.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a structure in which an organic photoreceptor layer, an intermediate layer if necessary, and a protective layer are laminated on the outermost surface in this order on a conductive support, the protective layer is the first layer. 1 and a second carbon or a film mainly composed of carbon, the resistivity of the second film being at least one order of magnitude smaller than the resistivity of the first film. body. 2. An electrophotographic photoreceptor according to claim 1, characterized in that the second coating has a hardness 50% or more greater than that of the first coating.