JPH07295277A - Electrophotographic photoreceptor and electrophotographic apparatus - Google Patents

Abstract

PURPOSE:To provide an electrophotographic photoreceptor having excellent electrophotographic characteristics, high hardness and excellent durability by containing a solvent-soluble polyaniline as a binder for a protective layer into a surface protective layer. CONSTITUTION:The surface protective layer of an electrophotographic photoreceptor 1 contains the solventsoluble polyaniline. The solvent-soluble polyaniline can be synthesized by chemical oxidation polymn. of aniline and includes a block polymer of a quinodiimine structure and p-phenylene diamine structure. If the p-phenylene diamine structure exists at a certain ratio or above in the polyaniline, the structure weakens the hydrogen bonds between the molecular chains and that is why the polyaniline is considered to have the solubility. While the mol.wt. of the polyaniline to be used is not particularly limited, the average mol.wt. of 1X10<4> to 1X10<7> is more preferable by taking the strength as the protective layer and the solubility in org. solvents into consideration. The volume resistivity of the protective layer is preferably 10<8> to 10<15>OMEGAcm. Image flow arises if the resistance is too low. The increase of residual potential arises if the resistance is too high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor and an electrophotographic apparatus having the same, and more particularly to an electrophotographic photoreceptor having a surface protective layer and an electrophotographic apparatus having the same.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member is required to have required sensitivity, electrical characteristics and optical characteristics according to an electrophotographic process to be used. For the surface layer of the photoreceptor, that is, the layer most distant from the support, corona charging, toner development,
Electrically such as transfer to paper, cleaning processing, or
Since external mechanical force is directly applied, durability against them is required. Specifically, it is required to have durability against abrasion and scratches on the surface due to rubbing, and deterioration of the surface due to ozone generated during corona charging.
On the other hand, there is a problem that the toner adheres to the surface layer due to repeated toner development and cleaning, and it is required to improve the cleaning property of the surface layer.

In order to satisfy the properties required for the surface layer as described above, attempts have been made to provide a surface protective layer containing a resin as a main component. For example, as disclosed in JP-A-57-207258 and JP-A-53-103741, a protective layer containing a curable resin as a main component is used,
The hardness and wear resistance are improved. However, when these curable resins are used as the surface protective layer, especially when the lower photosensitive layer is an organic photoreceptor also containing a resin as a main component, it is protected by shrinkage during curing of the curable resin. There is a problem that the layer or the photosensitive layer is apt to be susceptible to scratches. In addition to the surface properties such as high hardness and abrasion resistance, the characteristics required for the protective layer of the photoconductor are important control of the resistance of the protective layer itself. That is, when the resistance of the protective layer is too high, in the electrophotographic process in which charging-exposure is repeated, electric charges are accumulated in the protective layer itself, that is, the so-called residual potential increases, so that the potential becomes stable during repeated use of the photoconductor. Since it does not, the image becomes unstable. If the resistance is too low, an electrostatic latent image flows in the surface direction in the protective layer, causing problems such as image bleeding and blurring. In organic photoreceptors, the protective layer using these resins is still present. Hindered the practical application of.

In order to solve these problems, for example, as proposed in JP-A-57-30843,
Although a protective layer in which resistance is controlled by adding a metal oxide as conductive fine particles and a protective layer using a conductive polymer have been proposed, the metal oxide fine particles are uniformly dispersed in the conventional method. However, it is difficult to control the resistance to a desired value, and due to problems such as solubility of the conductive polymer, a protective layer having satisfactory electrophotographic characteristics has not yet been obtained.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to provide an electrophotographic photosensitive member which meets the above-mentioned requirements.
That is, an object of the present invention is to provide an electrophotographic photosensitive member that does not accumulate residual potential in repeated electrophotographic processes and exhibits stable electrophotographic characteristics, and an electrophotographic apparatus having the same. Another object of the present invention is to provide an electrophotographic photosensitive member having durability against abrasion of the surface due to rubbing and generation of scratches, and an electrophotographic apparatus having the same.

[0006]

According to the above-mentioned object, the inventors of the present invention have made extensive studies, and as a result, by including a solvent-soluble polyaniline in the surface protective layer as a binder for the protective layer, the electrophotographic characteristics are excellent and high. By inventing an electrophotographic photosensitive member that is excellent in hardness and durability, it has been possible to provide an electrophotographic photosensitive member that meets the above-mentioned requirements.

That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer on a conductive support,
An electrophotographic photoreceptor comprising the surface protective layer containing a solvent-soluble polyaniline, and an electrophotographic apparatus having the same.

The details of the present invention will be described below.

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a structure in which a photosensitive layer and a surface protective layer are layered in this order on a conductive support. First, the surface protective layer will be described below.

The solvent-soluble polyaniline used in the present invention can be synthesized by chemical oxidative polymerization of aniline. Examples of polyaniline include a quinodiimine structure and p-phenylene as shown in the following general formula (1). There is a block polymer having a diamine structure, and the solubility of polyaniline is considered to be soluble because the hydrogen bond between the molecular chains is weakened when the p-phenylenediamine structure is present at a certain ratio or more.

[0011]

[Chemical 1]

It is known that polyaniline has high conductivity by doping, and this is because the quinodiimine structure in polyaniline is doped with a protonic acid such as sulfuric acid, hydrofluoric acid or perchloric acid as a dopant, or , P-phenylenediamine structure by oxidative doping. The structure of polyaniline in this case shows various structures depending on the synthesis conditions of polyaniline, oxidation / reduction reaction by doping, and acid / base reaction, and it is difficult to show a simple structural formula. Therefore, polyaniline used in the present invention is The present invention is not limited to the above general formula (1) and shows a polymer of aniline obtained by chemical oxidative polymerization of aniline. The molecular weight of the polyaniline used in the present invention is not particularly limited, but in consideration of the strength as a protective layer and the solubility in an organic solvent, the weight average molecular weight is 1 × 10 ⁴ to 1 × 1.
0 ⁷ is preferable. These polyanilines may be used alone or may be used as a mixture with other commercially available resins such as polyimide resin, fluororesin, silicone resin, polyester resin, polyurethane resin and polyvinyl acetal resin. In the present invention, the volume resistance of the surface protective layer is 10 ⁸ to 10 ¹⁵ Ωcm, preferably 10 ¹⁰ to 10
^If the resistance is too low, image deletion occurs under high humidity, and if the resistance is too high, the residual potential rises repeatedly in the electrophotographic process. The control of the resistance of the surface protective layer is determined by the kind of the dopant added to the polyaniline, the addition amount, the ratio with another polymer to be mixed, and the like. In the present invention, the film thickness of the surface protective layer is not particularly limited, but is 0.5 μm to 10 μm, preferably 1 μm to 7 μm in consideration of the strength of the surface protective layer, the light transmittance, and the like. The surface protective layer is made of polyaniline by using THF, toluene, dioxane, MEK, acetonitrile, pyridine, DMF, DMAc, DMSO, NM.
It is formed by dissolving in a solvent such as P, applying this solution by dipping, spraying, etc., and drying.

The structure of the photosensitive layer of the electrophotographic photosensitive member of the present invention is a single layer type containing both a charge generating substance and a charge transfer substance, or a charge transporting layer and a charge generating layer are laminated on a conductive support. Any of the following laminated types can be used.

The laminated type photoreceptor will be described below.

As the constitution of the laminated type photosensitive layer, one in which a charge generating layer and a charge generating layer are laminated in this order on a conductive support, and one in which a conductive support, a charge transport layer and a charge generating layer are laminated in this order There is.

The support used in the present invention may be any support as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc or stainless formed into a drum or sheet, A metal foil such as aluminum or copper laminated on a plastic film, aluminum, indium oxide, tin oxide or the like deposited on a plastic film, a metal having a conductive layer formed by coating a conductive substance alone or with a binder resin, Examples include plastic film and paper.

The charge-transporting layer of the multi-layered photoreceptor is a nitrogen-containing polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene, phenanthrene in the main chain or side chain, indole, carbazole, oxadiazole, pyrazoline and the like. It is formed by using a coating liquid in which a charge transporting substance such as a ring compound, a hydrazone compound and a styryl compound is dissolved in a binder resin. As such a binder resin, polyester, polycarbonate, polystyrene,
Examples thereof include polymethacrylic acid ester. The thickness of the charge transport layer is usually 5 to 40 μm, preferably 10 to 30 μm.
m.

The charge generating layer of the multi-layer type photoreceptor is an azo pigment such as Sudan red or Diane blue, a quinone pigment such as pyrene quinone or anthanthrone, a quinocyanine pigment,
Perylene pigments, indigo pigments such as indigo and thioindigo, charge generating substances such as phthalocyanine pigments are dispersed in a binder resin such as polyvinyl butyral, polystyrene, polyvinyl acetate, and acrylic resin, and the dispersion liquid is applied or the pigment is applied. It is formed by vacuum evaporation. The thickness of such a charge generation layer is usually 5 μm.
The following is preferably 0.05 to 3 μm.

In the present invention, between the conductive layer and the photosensitive layer,
Alternatively, an intermediate layer having a barrier function and an adhesive function can be provided between the photosensitive layer and the surface protective layer. The intermediate layer is formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, alcohol-soluble polyamide, polyurethane, polyester, polycarbonate, gelatin and the like. A suitable film thickness of the intermediate layer is 0.1 to 3 μm.

FIG. 1 shows a schematic constitutional example of a transfer type electrophotographic apparatus using the electrophotographic photosensitive member of the present invention.

In the figure, reference numeral 1 is a drum type photosensitive member of the present invention as an image bearing member, which is rotationally driven around a shaft 1a in a direction of an arrow at a predetermined peripheral speed. The photosensitive member 1 is uniformly charged on its peripheral surface by a charging unit 2 at a predetermined potential in the course of its rotation, and then at an exposure unit 3 an optical image exposure L (slit exposure / laser beam scanning exposure) is performed by an image exposing unit (not shown). Such)
Receive. As a result, electrostatic latent images corresponding to the exposed image are sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then toner-developed by the developing means 4, and the toner-developed image is rotated by the transfer means 5 between the photosensitive member 1 and the transfer means 5 from a paper feeding portion (not shown). The images are sequentially transferred onto the surface of the transfer material P that is synchronously taken out and fed.

The transfer material P which has received the image transfer is separated from the surface of the photoconductor and is introduced into the image fixing means 8 where it is subjected to the image fixing and printed out as a copy.

After the image transfer, the surface of the photoconductor 1 is cleaned by the cleaning means 6 to remove the residual toner after transfer, and is further discharged by the pre-exposure means 7 to be repeatedly used for image formation.

As the uniform charging means 2 for the photosensitive member 1, a corona charging device or a contact charging device is used. As the transfer device 5, corona transfer means or contact charging means is used. The electrophotographic apparatus is configured by integrally combining a plurality of constituent elements such as the photoconductor, the developing unit, and the cleaning unit described above as an apparatus unit, and the unit is configured to be detachable from the apparatus body. May be.
For example, the photosensitive member 1 and the cleaning means 6 may be integrated into one device unit, and may be detachably configured by using guide means such as a rail of the device body. At this time,
The above device unit may be provided with a charging unit and / or a developing unit.

When the electrophotographic apparatus is used as a copying machine or a printer, the optical image exposure L is reflected light or transmitted light from a document, or the document is read and converted into a signal, and a laser beam is scanned based on this signal. Or driving an LED array or a liquid crystal shutter array.

When the electrophotographic apparatus of the present invention is used as a printer for a facsimile, the light image exposure L becomes an exposure for printing received data. FIG. 2 is a block diagram showing an example of this case.

The controller 11 controls the image reading section 10 and the printer 19. The entire controller 11 is CP
It is controlled by U17. The read data from the image reading unit 10 is transmitted to the partner station through the transmission circuit 13. The data received from the partner station is sent to the printer 19 through the receiving circuit 12. The image memory 16 stores predetermined image data. The printer controller 18 controls the printer 19. 14 is a telephone.

The image information received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, then decoded by the CPU 17, and sequentially stored in the image memory 16. Is stored. When the image information of at least one page is stored in the memory 16, the image recording of that page is performed. The CPU 17 reads out one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18. Upon receiving the image information of one page from the CPU 17, the printer controller 18 controls the printer 19 to record the image information of the page.

The CPU 17 is receiving the next page during recording by the printer 19.

The image is received and recorded as described above.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in laser beam printers and CRs.
It can be widely used in electrophotographic application fields such as T printers, LED printers, liquid crystal printers, and laser plate making.

[0033]

EXAMPLES The present invention will be described in more detail with reference to specific examples. In the examples, “part” means “part by weight”. Example 1 An alcohol-soluble polyamide resin (Amilan CM-800) was placed on an aluminum cylinder (φ30 mm × 260 mm).
0, Toray Co., Ltd. 10 parts and methoxymethylated 6 nylon resin (Toresin EF-30T, Teikoku Kagaku Co., Ltd.)
30 parts of a prepared solution prepared by dissolving 30 parts in a mixed solvent of 150 parts of methanol and 150 parts of butanol was applied by dip coating and dried at 90 ° C. for 10 minutes to form an undercoat layer having a film thickness of 1 μm.

Next, a disazo pigment represented by the following structural formula

[0035]

[Chemical 2] 4 parts, 2 parts of butyral resin (S-REC BL-S, manufactured by Sekisui Chemical Co., Ltd.) and 100 parts of cyclohexanone were dispersed in a sand mill for 48 hours, and then 100 parts of tetrahydrofuran (THF) was added to disperse the charge generation layer. The liquid was prepared. The dispersion is dip-coated on the undercoat layer,
By drying at 15 ° C. for 15 minutes, a charge generation layer having a thickness of 0.15 μm was formed.

Next, the following structural formula

[0037]

[Chemical 3] 10 parts of a styryl compound represented by and a polycarbonate resin (Upilon Z-200, manufactured by Mitsubishi Gas Chemical Co., Inc.)
10 parts was dissolved in a mixed solvent of 20 parts of dichloromethane and 60 parts of monochlorobenzene, the solution was applied onto the charge generation layer by dip coating, and dried at 120 ° C. for 60 minutes,
A charge transport layer having a film thickness of 18 μm was formed.

Next, the following structural formula

[0039]

[Chemical 4] Polyaniline (m: n = 3: 7, weight average molecular weight 15
50,000) 5 parts N-methyl-2-pyrrolidone (NM
P) was dissolved in 95 parts, the solution was spray-coated on the charge transport layer and dried at 140 ° C. for 1 hour to give a film thickness of 1.
A surface protective layer having a thickness of 5 μm was formed to obtain a photoconductor.

The electrophotographic photosensitive member thus prepared was attached to a copying machine in which the process of charging, exposure, development, transfer and cleaning was repeated in a cycle of 1.5 seconds, and electrophotographic characteristics were evaluated. The image evaluation was repeated. As a result, the sensitivity and residual potential were almost the same as those of the photoconductor without the surface protective layer shown in Comparative Example 1, and an image without unevenness or black spots could be obtained. Moreover, a stable image could be maintained even when the image was repeatedly displayed 10,000 times. The results are shown in Table 1. The dark part potential is the surface potential of the photoconductor when discharged at a corona discharge voltage of -5 kV, and the larger the value, the better the charging ability. In addition, the sensitivity is such that the surface potential is from 650V to 15
The exposure amount required to attenuate to 0 V is shown.

Example 2 Up to the charge transport layer was formed in the same manner as in Example 1.

Next, the following structural formula

[0043]

[Chemical 5] Polyaniline represented by (weight average molecular weight of 20,000
0) 5 parts was dissolved in 95 parts NMP, and 1 part 1 mol / l oxalic acid (NMP solution) was added to prepare a preparation liquid for the surface protective layer. The charge-transporting layer was spray-coated with this formulation and dried at 140 ° C. for 1 hour to give a film thickness of 5 μm.
A surface protective layer of m was formed to obtain a photoreceptor.

Example 3 Up to the charge transport layer was formed in the same manner as in Example 1.

Next, 2 parts of polyaniline and 3 parts of polyetherimide resin (ULTEM1000, manufactured by Engineering Plastics Co., Ltd.) used in Example 2 were NMP.
Dissolved in 95 parts, 1 mol / l oxalic acid (NMP solution)
1 part was added to prepare a preparation liquid for the surface protective layer. This formulation is spray-coated on the charge transport layer at 140 ° C.
After drying for 1 hour, a protective layer having a film thickness of 3 μm was formed to obtain a photoreceptor.

Comparative Example 1 A photosensitive member was prepared in the same manner as in Example 1 except that the surface protective layer was omitted, and the same evaluation was carried out.
As a result, as shown in Table 1, the electrophotographic characteristics were good in the initial stage, but when the durability was increased, the charging ability was lowered, and
A good image could not be obtained from around 00 sheets.

Comparative Example 2 A photoconductor was prepared and evaluated in the same manner as in Example 1 except that a polyetherimide resin was used as the binder resin for the surface protective layer. As a result, the residual potential was high and the image had background stains.

[0048]

The electrophotographic photosensitive member of the present invention has a surface protective layer containing a solvent-soluble polyaniline on the photosensitive layer, and according to the present invention, it has high hardness, excellent durability characteristics, and stable low residual potential. A photoconductor having electrophotographic characteristics and an electrophotographic apparatus having the photoconductor were obtained. As a result, fog,
It has become possible to provide an electrophotographic photosensitive member which is free from image defects such as black spots and is excellent in durability characteristics and image stability, and an electrophotographic apparatus having the same.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a transfer type electrophotographic apparatus of the present invention.

FIG. 2 is a block diagram of a facsimile using the electrophotographic apparatus as a printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 3 Exposure part 4 Developing means 5 Transfer means 6 Cleaning means 7 Pre-exposure means 8 Image fixing means

Claims (2)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer and a surface protective layer on a conductive support, wherein the surface protective layer contains a solvent-soluble polyaniline. 2. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1.