JPH0968813A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce an electrophotographic photoreceptor and to improve the surface accuracy, especially roundness, straightness, eccentricity and overall strength by forming a resin layer on a raw tube, shaping the resin layer, and forming an org. photosensitive layer on the base body. SOLUTION: As for the raw tube material, a hard plastic tube having about 30-150mm outer diameter and about 2-10mm thickness is used. A thermosetting transparent resin layer such as polymethyl methacrylate having lower hardness than the raw tube, good workability and solvent resistance is formed on the tube. The resin layer is processed by shaping or by shaping and polishing to have about 50-100μm thickness and that a precise finish state of the base body having high roundness and straightness which is suitable for image forming is obtd. Then, a transparent conductive layer and a base layer are formed on the base body, and a laminated org. photoreceptor comprising a charge generating layer and a charge transfer layer is formed thereon. The material of the raw tube is preferably harder than the resin layer. The obtd. photoreceptor is suitable for long-term use and an image excellent in uniformity without color slurry or irregular color can be obtd.

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 used in an image forming apparatus for forming an image by an electrophotographic method.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image by an electrophotographic method, a rotating drum or belt-shaped electrophotographic photosensitive member (electrostatic image forming member) is charged, image-exposed and developed to perform the electrophotography. A toner image is formed on a photoconductor, and the toner image is transferred and fixed on a transfer material. In order to fulfill its function, the electrophotographic photosensitive member is provided with a charging device, an exposure device, a developing device, a transfer device, a charge eliminator, a cleaning device, or the like arranged around the electrophotographic photosensitive member,
It must be moved at a constant speed at a predetermined timing, maintained without changing the pressure contact state. In order to be used repeatedly, when the role in the image forming process of one cycle is completed, it is necessary to return to the original position in the original state in preparation for the next image forming cycle. In order to smooth this series of movements and to efficiently use expensive members such as electrophotographic photosensitive members, in practically used devices, an electrophotographic photosensitive member is provided with a photosensitive layer almost on the peripheral surface of a cylindrical substrate. Although the photoconductor drum provided is used, a metal material such as aluminum is often used as the material of the cylindrical substrate. However, there is a limit to cost reduction in forming a cylindrical substrate by machining using a metal material.

Further, a plurality of sets of charging means, image exposing means and developing means are provided in the vicinity of the photosensitive drum, and
During rotation, charging, image exposure and development are repeated to form multicolor toner images on the photoconductor, and the multicolor toner images formed on the photoconductor are collectively transferred to the transfer material. An image forming apparatus is provided. Further, there has been proposed an image forming apparatus in which an image exposure unit is provided inside the photoconductor drum in the above-mentioned image formation, and image exposure is performed from the inside of the photoconductor drum. The cylindrical substrate of such a photosensitive drum needs to be transparent to the light exposed from the inside, and metal cannot be used for the substrate material. In the image forming method in which image exposure is performed from the inside, glass or transparent resin is used as the base material of the electrophotographic photosensitive member.

When glass is used as the substrate material, an electrophotographic photosensitive member can be manufactured by applying a photosensitive layer on the glass tube, but a glass tube manufactured by the Dunner method or the like generally has dimensional accuracy of inner and outer diameters. It is difficult to produce, and it is difficult to perform cutting work, and a large number of processing steps are required to obtain a highly accurate glass tube by polishing work. When a transparent plastic is used as the base material, a plastic pipe is produced by an extrusion molding method, a mold molding method, etc. However, even in this case, accuracy cannot be obtained by molding as it is, and therefore, a cutting process or the like is required. It is necessary to go and get a high precision plastic tube. However, since the plastic used as the base material requires strength and heat resistance, the molded plastic is brittle and is generally unsuitable for cutting.

[0005]

SUMMARY OF THE INVENTION The present invention is an electrophotographic photosensitive member used in the above-mentioned image forming apparatus, which can be industrially produced efficiently, and has surface accuracy, particularly roundness, straightness,
An object of the present invention is to provide an electrophotographic photosensitive member having a photosensitive layer on a cylindrical substrate, which has good dimensional accuracy with respect to deflection (eccentricity) and the like, has high overall strength, and has sufficiently high transparency as necessary.

[0006]

The above object is to provide an electrophotographic photosensitive member having an organic photosensitive layer formed on a substrate, wherein the substrate is (1) a resin layer forming step of forming a resin layer on a base cylinder (2) This is achieved by an electrophotographic photosensitive member characterized by being formed through steps (1) and (2) of a resin layer processing step of scraping a resin layer.

In the above invention, the barrel is preferably made of glass or plastic in a cylindrical shape, and the barrel is preferably made of a material harder than the resin layer. The resin layer is preferably made of a thermosetting resin, and the resin layer preferably has conductivity and also serves as a conductive layer.

The electrophotographic photosensitive member of the present invention having the above characteristics is preferably used in an image forming apparatus which performs image exposure from the back surface of the photosensitive layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows a manufacturing process of the electrophotographic photosensitive member of the present invention, and FIG. 2 shows an enlarged sectional view of the manufactured electrophotographic photosensitive member. A description will be given according to the manufacturing process of FIG.

Manufacture of a bare cylinder Glass or hard plastic is used as a bare barrel material having high hardness, heat resistance, and high transparency. In the case of a glass tube, it is produced by the Dunner method or the like, and in the case of a plastic tube, it is produced by extrusion molding or molding. Glass tube or plastic tube has a wall thickness of 2-10 mm
Is set between. If the wall thickness is 2 mm or less, there is concern about the strength, and if it is 10 mm or more, the image length is longer than the focal length of the imaging system of the SELFOC lens as an equal-magnification imaging element when image exposure is performed through the substrate. Become. The outer diameter of the glass tube or the plastic tube depends on the image forming apparatus incorporated, but a cylinder having a small diameter of 30 mm to 150 mm is selected.

Forming a resin layer on a blank cylinder It is difficult to directly finish the blank cylinder due to the material of the blank cylinder, so it is easier to finish such as cutting and polishing. The resin layer is formed on the bare cylinder.
This resin layer is a thermosetting transparent resin layer, and a resin material having solvent resistance is selected, and is coated on the outer side (inner side if necessary) of the bare cylinder by a dipping method. By using the thermosetting type, it is possible to prevent the resin layer from being dissolved or swelled at the time of coating the conductive layer, the undercoat layer and the photosensitive layer which are the upper layers. These thermosetting coating resins include polymethylmethacrylate, polyethylmethacrylate, polybutylmethacrylate, polyethylacrylate, butylpolyacrylate, polystyrene, polyimide, polyester or polyvinyl chloride, or the like. It is also possible to use a resin such as a copolymer which can be polymerized by heating and has transparency. The thickness of the resin layer to be coated is determined by the accuracy of the inner and outer diameters of the bare cylinder, but generally 500 μm or less is sufficient. It is also possible to add conductive fine powder to this resin material to impart conductivity.

By mixing a cross-linking agent, a conductivity-imparting agent, a coloring agent and the like with the polymerizable liquid material in the resin layer,
More preferable physical properties can be realized. For example, the addition of a cross-linking agent improves heat resistance, solvent resistance, and strength, and the conductivity-imparting agent can prevent electrostatic contamination such as dust and replace the conductive layer. These are effective for an electrostatic image forming body which is subjected to external force or heat during use or a solution is coated on a substrate.

Finishing of the resin layer The base body in which the resin layer is coated on the bare cylinder is subjected to the precision processing of the resin layer portion by cutting or by cutting and polishing to leave a resin layer of about 50 to 100 μm. Thus, the substrate is subjected to finishing processing suitable for image formation with high roundness and parallelism. The surface of the substrate after processing is washed with an aqueous cleaning solution. It is preferable that the base cylinder is made of a hard material to maintain its strength, and the resin layer is made soft so as to improve the machinability, thereby facilitating the production of the base body.

Formation of transparent conductive layer The transparent conductive layer is formed by vapor deposition or sputtering of a metal or metal oxide such as aluminum or ITO (indium tin oxide), or IT.
A typical example of the method is to form a coating film of a conductive resin with a mixture of O or alumina conductive fine particles and a resin.
It is formed on the resin layer to a thickness of μm. It is omitted when the resin layer has conductivity.

Formation of Undercoat Layer An undercoat layer is formed on the surface of the cleaned substrate by using at least one selected from a metal alkoxide, an organometallic chelate and a silane coupling agent. The undercoat layer is preferably formed of a material containing an organometallic chelate represented by the following general formula (1) and a silane coupling agent represented by the following general formula (2).

General formula (1) (RO) mMXn General formula (2) ZaAbSiYc In the general formula (1), R represents an alkyl group, M represents titanium, zirconium or aluminum, and X is a chelate-forming group and acetoacetic ester. Alternatively, it represents a β-diketone residue, and m and n represent an integer of 1 or more. However, when M is titanium or zirconium, m + n is 4,
When M is aluminum, m + n is 3. Equation (2)
In the formula, Z is a hydrolyzable group and represents an alkoxy group, a halogen atom or an amino group, A is an alkyl group or an aryl group, and Y is an organic functional group having an amino group at the terminal, that is, -BOOC (R ') C. = CH ₂ , -BNHR "or-
Represents BNH ₂ . R'represents an alkyl group, R "represents an alkyl group or an aryl group, B represents an alkylene group or an alkylene group including -O-, -NH-, and -CO-. A and c are integers of 1 or more. And b represents an integer of 0 or more, and a + b + c is 4.

In the formula (1), M is particularly preferably titanium. 2 is particularly preferable for m and n.

The thickness of the undercoat layer is 0.1 to 10 μm.
Is preferable, and 0.1 to 5 μm is particularly preferable.

Formation of Organic Photoreceptor As the photoconductive layer provided on the undercoat layer, an organic photoreceptor is used in view of prevention of environmental pollution. As the organic photoreceptor, there is used a so-called layered organic photoreceptor which is composed of a charge generation layer and a charge transport layer on a conductive layer with an undercoat layer, or a photoreceptor in which a charge generation substance and a charge transport substance are mixed.

The charge generating layer is a layer containing a charge generating substance, and the charge generating substance is not particularly limited, and examples thereof include a phthalocyanine pigment, a polycyclic quinone pigment, an azo pigment, a perylene pigment, and an indigo. Pigments, quinacridone pigments, azurenium pigments, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, triphenylmethane dyes, styryl dyes and the like can be used, and these are formed alone or dispersed in a resin. The resin used here is styrene-
Acrylic resin, bisphenol A type polycarbonate,
Bisphenol Z-type polycarbonate, polyester resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, styrene resin, polyvinyl acetate, styrene-butadiene resin, vinylidene chloride-acrylonitrile resin, vinyl chloride-vinyl acetate resin, vinyl chloride-vinyl acetate -Maleic anhydride resin, silicone resin,
Examples include silicone alkyd resin, phenol formaldehyde resin, polyvinyl acetal resin, polyvinyl butyral resin, and the like. The film thickness of the charge generation layer is 0.1 to 5 μm, preferably 0.1 to 3 μm.

The charge-transporting layer is a layer containing a charge-transporting substance, and the charge-transporting substance is not particularly limited, and examples thereof include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives and triazole derivatives. , Imidazole derivative, imidazolone derivative, imidazoline derivative, bisimidazolidine derivative, styryl compound, hydrazone compound, benzidine compound, pyrazoline derivative, stilbene compound, amine derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative , Benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, poly-N-vinylcarbazoles, poly-1-vinylpyrenes, poly-9-vinylant Mosses and the like. These are formed singly or in combination and dispersed or dissolved in a resin. The resin used here is styrene-
Acrylic resin, bisphenol A type polycarbonate,
Bisphenol Z-type polycarbonate, polyester resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, styrene resin, polyvinyl acetate, styrene-butadiene resin, vinylidene chloride-acrylonitrile resin, vinyl chloride-vinyl acetate resin, vinyl chloride-vinyl acetate -Maleic anhydride resin, silicone resin,
Examples include silicone alkyd resin, phenol formaldehyde resin, polyvinyl acetal resin, polyvinyl butyral resin, and the like. The thickness of the charge transport layer is 5 to 50 μm, preferably 10 to 40 μm.
It is. The charge transport layer is provided above or below the charge generation layer.

In the case of a single-layered photosensitive layer composed of a mixture of a charge transport substance and a charge generating substance, the charge transport substance and the charge generating substance described above are appropriately mixed, and It is obtained by forming a layer after dispersing in. In this case, the layer thickness is 5 to 50 μm, preferably 10 to 40
μm.

In order to reduce fatigue deterioration after repeated use of the organic photoconductor or to improve durability, the organic photoconductor described above may be used in any one of the layers of the photoconductor, such as a conventionally known antioxidant or ultraviolet absorber, An electron-accepting substance, a surface modifier, a plasticizer, etc., an environment-dependent reducing agent, etc. may be added in an appropriate amount, if necessary.

If desired, a non-photosensitive layer such as a protective layer may be provided on the surface of the photosensitive layer for the purpose of improving durability.

Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described using the color image forming apparatus shown in FIG. FIG. 3 is a cross-sectional configuration diagram of a color image forming apparatus showing an example of an image forming apparatus to which the electrophotographic photosensitive member manufactured by the manufacturing process of FIG. 1 described above is applied.

Numeral 10 is a photosensitive member which is a drum-shaped electrostatic charge image forming body, and a resin layer made of highly transparent polymethylmethacrylate polymer resin is formed on a glass tube, which is subjected to precision processing. A transparent conductive layer and a function-separated organic photosensitive layer composed of a charge generation layer and a charge transfer layer are formed on the outer periphery of the obtained cylindrical substrate having high circularity and parallelism. 110Y, 110M, 110C and 110K are scorotron charging devices used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and are the above-mentioned organic photosensitive layers of the photoconductor 10. On the other hand, in order to hold the electric charge of a predetermined potential, a charging action is performed by corona discharge, and a uniform potential is given to the photoconductor 10.

12Y, 12M, 12C and 12K are
FL (phosphor emission), EL (electroluminescence), PL (plasma discharge), LED (light emitting diode), and lamp and optical shutter functions in which light emitting elements arranged in the axial direction of the photoconductor 10 are arranged in a line in an array. LISA (Opto-Magnetic Effect Optical Shutter Array) in which elements with
PLZT (transmissive piezoelectric element shutter array), LCS
An image of each color read by a separate image reading device with an exposure optical system that is an image exposure device configured as a unit with an exposure element such as a (liquid crystal shutter) and a SELFOC lens as a unity-magnification imaging element. The signals are sequentially taken out from the memory and the exposure optical systems 12Y, 12M, 1
It is input as an electric signal to each of 2C and 12K.
The exposure optical systems 12Y, 12M, 12C and 12K
Each of them is attached to a cylindrical holding member 20 and accommodated inside the base of the photoconductor 10.

13Y, 13M, 13C and 13K are developing devices which are non-contact developing devices for accommodating yellow (Y), magenta (M), cyan (C) and black (K) developers. And a developing sleeve 13 that rotates in the same direction with a predetermined gap with respect to the peripheral surface of the photoconductor 10, respectively.
It is equipped with 0Y, 130M, 130C and 130K.

The developing units 13Y, 13M, 13C and 13K are the corona charging devices 110Y and 110 described above.
Optical system 1 for charging and exposing by M, 110C and 110K
The electrostatic latent image formed on the photoconductor 10 by image exposure with 2Y, 12M, 12C and 12K is reversely developed in a non-contact state by applying a developing bias voltage.

In the image reading apparatus which is a separate body from this apparatus, the original image is an image read by an image pickup device or an image edited by a computer is once used as an image signal for each color of Y, M, C and K. Stored and stored in memory.

When image recording is started, the photosensitive member driving motor is started to rotate the photosensitive member 10 in the clockwise direction, and at the same time, the corona charging device 110Y charges the photosensitive member 10.
Application of electric potential is started.

After a potential is applied to the photoconductor 10, the exposure optical system 12Y starts exposure by an electric signal corresponding to the first color signal, that is, an image signal of yellow (Y), and the drum is rotationally scanned to expose it. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface.

The latent image is reversal-developed by the developing device 13Y with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further covered with the corona charging device 110M on the yellow (Y) toner image.
Is applied with a potential by the charging action of the exposure optical system 12M, the exposure is performed by an electric signal corresponding to the second color signal of the exposure optical system 12M, that is, the image signal of magenta (M), and the non-contact reverse development by the developing device 13M causes A magenta (M) toner image is sequentially formed on the yellow (Y) toner image.

By the same process, the corona charging device 11
0C, the exposure optical system 12C and the developing device 13C further convert a cyan (C) toner image corresponding to the third color signal into a fourth color signal by the corona charging device 110K, the exposure optical system 12K and the developing device 13K. Corresponding black (K) toner images are sequentially superposed and formed, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation.

These exposure optical systems 12Y, 12M, 12C
The exposure of the organic photosensitive layer of the photoconductor drum 10 by (1) and (12K) is performed from the inside of the substrate through the transparent substrate described above. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals is performed without any influence of the toner image previously formed, and is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image. In order to stabilize the temperature inside the photoconductor drum and prevent the temperature rise due to the heat generated by the exposure optical systems 12Y, 12M, 12C and 12K, a material having good thermal conductivity is used for the holding member 20, and a heater is used at low temperature. In the case of high temperature, it is possible to suppress the heat to the outside by taking measures such as radiating heat to the outside through a heat pipe. Further, during the developing operation by the developing devices 13Y, 13M, 13C and 13K, the developing sleeves 130Y, 130M,
A developing bias in which a direct current or an alternating current is applied to 130C and 130K is applied, and jumping development is performed by a one-component or two-component developer accommodated in the developing device, so that the photoconductor 10 that grounds the transparent conductive layer is grounded. On the other hand, a non-contact reversal development in which a DC bias having the same polarity as that of the toner is applied to attach the toner to the exposed portion is performed.

In this way, the color toner image formed on the peripheral surface of the photosensitive drum is sent out from the paper feeding cassette 15 by the sending roller 15a in the transfer device 14a, and to the timing roller 16 by the carrying roller pair 15b and 15c. The sheet is conveyed, and is driven by the timing roller 16 to be transferred onto a transfer sheet P that is a transfer material that is fed in synchronization with the toner image on the photoconductor 10.

The transfer paper P on which the toner image has been transferred is removed from the charge by the static eliminator 14b and separated from the peripheral surface of the drum, and then the transport drive roller 14c and the driven roller 14d.
The fixing device 17 is provided by the conveyance belt 14e stretched between
In the fixing device 17, the fixing roller 17 is conveyed to
a, the toner is fused and fixed on the transfer paper P by being heated and pressure-bonded between the pressure roller 17b and the fixing outlet roller pair 17d.
Is discharged from the fixing device 17 by the
8a, and the sheet is discharged onto the sheet discharge tray 200 at the upper part of the apparatus through the sheet discharge roller 18, but the one using the photosensitive drum 10 having the photosensitive layer on the cylindrical substrate of the present invention described above is used. A clear and extremely good image was obtained.

On the other hand, the photosensitive member 10 from which the transfer paper has been separated is cleaned by the cleaning blade 19a in the cleaning device 19.
Thus, the surface of the photoconductor 10 is rubbed to remove and clean residual toner, and the toner image of the original image is continuously formed or is temporarily stopped to form a new toner image of the original image. The waste toner scraped off by the cleaning blade 19a is removed by the toner transport screw 19b.
It is discharged to a waste toner container (not shown).

Image Output Evaluation An electrophotographic photoconductor having a photosensitive layer provided on a cylindrical substrate of the present invention was mounted on an electrophotographic internal exposure type color image forming apparatus having the structure shown in FIG. As a result, no color shift was found in the toner images of the respective colors, and an image with sufficient density without fog was obtained. In particular, no unevenness of density or color tone was observed on the image, and an image having excellent uniformity was obtained. In such an image having excellent uniformity, no change in image quality was observed even after continuous 10,000 prints.

[0041]

Industrial Applicability According to the present invention, it has been possible to develop a cylindrical electrophotographic photosensitive member for an electrostatic charge image forming apparatus which can be industrially produced efficiently, has high surface accuracy and high overall strength. If necessary, an electrophotographic photosensitive member having a highly transparent substrate can be developed. By using this electrophotographic photosensitive member in a color image forming apparatus, excellent uniformity without color misregistration or color unevenness can be obtained. An image was obtained, and an image forming apparatus having excellent performance suitable for long-term use could be manufactured.

[Brief description of drawings]

FIG. 1 is a process drawing of a method for manufacturing an electrophotographic photosensitive member of the present invention.

FIG. 2 is an enlarged cross-sectional view of the electrophotographic photosensitive member of the present invention.

FIG. 3 is a sectional configuration diagram of an image forming apparatus using the electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

10 Photoconductor (photoconductor drum) 12Y, 12M Yellow and magenta exposure optical system (exposure device) 12C, 12K Cyan, black exposure optical system (exposure device) 13Y, 13M Yellow, magenta 13C, 13K Cyan, black development Device 110Y, 110M Yellow, magenta 110C, 110K Cyan, black corona charging device 15 Paper feed cassette 16 Timing roller 17 Fixing device 19 Cleaning device P Transfer paper

Claims (6)

[Claims] 1. An electrophotographic photoreceptor in which an organic photosensitive layer is formed on a substrate, wherein the substrate is (1) a resin layer forming step of forming a resin layer on a base cylinder, and (2) a resin layer processing step of scraping the resin layer. An electrophotographic photosensitive member formed by the steps (1) and (2). 2. The electrophotographic photosensitive member according to claim 1, wherein the base cylinder is a cylindrical glass or plastic. 3. The electrophotographic photosensitive member according to claim 1, wherein the base cylinder is made of a material harder than the resin layer. 4. The electrophotographic photosensitive member according to claim 1, wherein the resin layer is made of a thermosetting resin. 5. The electrophotographic photosensitive member according to claim 1, wherein the resin layer has conductivity and also serves as a conductive layer. 6. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is used in an image forming apparatus that performs image exposure from the back surface of a photosensitive layer.