JPH07181705A - Electrophotographic photoreceptor and electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor excellent in durability and an electrophotographic device having this photoreceptor with which images with high resolution and good contrast can be obtd. CONSTITUTION:This electrophotographic photoreceptor has a photoconductive layer of <=15mum thickness on a conductive layer and has a surface protective layer having >=1X10<15>OMEGA surface resistance, <=1X10<12>OMEGAcm volume resistance in the direction of the cross section, and 1 to 10mum thickness. The electrophotographic device has this electrophotographic photoreceptor. Thereby, an electrophotographic photoreceptor having excellent durability and an electrophotographic device using that are realized with which images with high resolution and good contrast 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 which can be widely used in copying machines, printers, facsimiles, plate making systems and the like using an electrophotographic system, and an electrophotographic apparatus having the same. More specifically, the present invention relates to an electrophotographic photoreceptor having high resolution and excellent durability, and an electrophotographic apparatus having the same.

[0002]

2. Description of the Related Art In recent years, the development of organic photoconductive materials has progressed and is widely used as an electrophotographic photoreceptor for copying machines and printers. These photoconductors generally have low durability, and in consideration of a decrease due to wear or the like, they are applied and formed with a considerably thick film thickness. On the other hand, as the image quality and resolution of copiers and printers have advanced and the resolution of the photoconductor itself has been required to be improved, the film thickness of the photoconductor layer must be reduced to reduce the diffusion of photocarriers. However, it was difficult to satisfy the durability at the same time.

[0003]

SUMMARY OF THE INVENTION The present invention provides an electrophotographic photoreceptor having high resolution and high durability that meets the above-mentioned demands. That is, an object of the present invention is to provide a surface protective layer which provides sufficient durability even when the photoconductive layer is thinned for high resolution, and does not bring about a decrease in resolution by forming it. An object is to provide an electrophotographic photoreceptor.

[0004]

That is, the present invention provides an electrophotographic photosensitive member having a photoconductive layer having a thickness of 15 μm or less on a conductive layer, the photosensitive member having a surface resistance of 1 × 10 ¹⁵ Ω or more,
Volume resistance in the cross-sectional direction 1 × 10 ¹² Ωcm or less and thickness 1 to
An electrophotographic photoreceptor having a surface protection layer of 10 μm.

Further, the present invention is an electrophotographic apparatus comprising the above electrophotographic photosensitive member.

Generally, when the ratio (S / L) of the film thickness (L) of the photoconductive layer and the resolution (S) of the recorded image is small, the latent image is blurred due to the diffusion of the photocarrier, and a good image is obtained. I can't. The ratio (S / L) is preferably 4 or more, and more preferably 5 or more. The currently required resolution is 400 dpi or more, more preferably 500 dpi or more, and the thickness of the photoconductive layer used is 15 μm or less, preferably 13 μm or less, more preferably 12 to 4 μm. A surface protective layer is required to use such a thin photoconductive layer, but in general, diffusion of photocarriers occurs in the surface protective layer, which causes deterioration of image quality and is not desirable. The surface protective layer used in the present invention has anisotropic conductivity with respect to such problems, so that surface protection and high resolution are compatible with each other.

More specifically, for example, acicular fine particles having an aspect ratio of 1:10 or more, preferably 1:15 to 300 are contained in the insulating polymer in an amount of 10% by weight or more, preferably 15%.
-30% by weight and oriented to have a surface resistance of 1 × 10 ¹⁵ Ω or more, preferably 2 × 10 ¹⁵ to 2 × 1.
0 is ¹⁷ Omega, the volume resistivity in the cross-sectional direction is 1 × 10 ¹² Ωcm
Below, a surface protective layer having a thickness of preferably 8 × 10 ^{11 to} 5 × 10 ⁸ Ωcm is obtained. As another method, by forming a chain body by polarization orientation of fine particles,
A surface protective layer having a surface resistance of 1 × 10 ¹⁵ Ω or more and a volume resistance in the cross-sectional direction of 1 × 10 ¹² Ωcm or less can be obtained. If the surface resistance is less than 1 × 10 ¹⁵ , image diffusion occurs due to surface charge diffusion and the resolution is reduced. Further, if the volume resistance in the cross-sectional direction exceeds 1 × 10 ¹² Ωcm, the residual potential rises and the potential contrast decreases, so that the image quality deteriorates, which is not preferable. The surface resistance is measured by a commercially available surface resistance meter or the four-terminal method. The volume resistance in the cross-sectional direction is measured by sandwiching a surface protective layer having the same structure as that of the electrophotographic photosensitive member used, between a conductive substrate such as an aluminum substrate. For accurate measurement, a guard ring is provided to remove the influence of the edge and the measurement is performed. The surface protective layer has a thickness of 1 to 10 μm. 1 μm
If it is less than 10 μm, the protective effect is not sufficient, and if it exceeds 10 μm, the surface potential decreases, which is not preferable. As the acicular fine particles having an aspect ratio of 1:10 or more, there are whiskers such as titanium oxide, aluminum borate and potassium titanate.

When the electrophotographic photosensitive member of the present invention is manufactured,
As the substrate, one having conductivity in itself, for example,
Aluminum, aluminum alloy, copper, zinc, stainless steel, chromium, titanium, nickel, magnesium, indium, gold, platinum, silver, iron and the like can be used. In addition, it is possible to use a conductive layer formed by coating aluminum, indium oxide, tin oxide, gold or the like on a dielectric substrate such as plastic by vapor deposition or a mixture of conductive fine particles with plastic or paper. it can.

An undercoat layer having an injection blocking function and an adhesive function can be provided between the conductive substrate and the photoconductive layer. The subbing layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, polyamide, polyurethane, gelatin or the like. The thickness of the undercoat layer is 0.1 μm to 10 μm, preferably 0.3 μm
Is about 3 μm.

As the photoconductive layer, a function-separated type layer composed of a charge generation layer and a charge transport layer and a single layer type in which charge generation and charge transport are performed in the same layer are used. Examples of the charge generation material include selenium-tellurium, pyrylium dyes, thiopyrylium dyes, phthalocyanine pigments, anthanthrone pigments, dibenzpyrenequinone pigments,
Pyrantron pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, cyanine pigments and the like can be used.

As the charge transport material, a polymer compound having a heterocyclic ring or a condensed polycyclic aromatic compound such as poly-N-vinylcarbazole or polystyrylanthracene, or pyrazoline,
Heterocyclic compounds such as imidazole, oxazole, oxadiazole, triazole, carbazole, triarylalkane derivatives such as triphenylmethane, triarylamine derivatives such as triphenylamine, phenylenediamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, A low molecular weight compound such as a hydrazone derivative can be used.

If necessary, a binder polymer is used in combination with the charge generating material and the charge transporting material. Examples of the binder polymer, styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, polymers and copolymers of vinyl compounds such as trifluoroethylene, polyvinyl alcohol, polyvinyl acetal, polycarbonate, Examples thereof include polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin and epoxy resin.

In addition to the above compounds, additives can be used in the photoconductive layer in order to improve mechanical properties and durability. As such additives, antioxidants, ultraviolet absorbers, stabilizers, cross-linking agents, lubricants, conductivity control agents and the like are used.

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

In the figure, reference numeral 1 denotes a drum type photosensitive member of the present invention as an image bearing member, which is rotationally driven around an axis 1a in a direction of an arrow at a predetermined peripheral speed. In the course of its rotation, the photosensitive member 1 is uniformly charged at its periphery with a positive or negative predetermined potential by the charging means 2, and then in the exposure unit 3 an optical image exposure L (slit exposure / laser) is performed by an image exposing means (not shown). Beam scanning exposure). 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 photoconductor 1 and the transfer means 5 from a paper feed 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 that 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.

The surface of the photoconductor 1 after the image transfer 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 a uniform charging means 2 for the photosensitive member 1, a corona charging device or a contact charging device is generally widely used. As the transfer device 5, corona transfer means or contact charging means are generally widely 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. Alternatively, for example, the photosensitive member 1 and the cleaning unit 6 may be integrated into one device unit, and the device unit may be detachable by using a guide unit 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 a document is read out 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 at least one page of image information is stored in the memory 16, the image of that page is recorded. The CPU 17 reads out one page of image information from the memory 16 and the printer controller 18 decodes the decoded page of one page. Send image information. 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 while the printer 19 is recording.

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 C
RT printer, LED printer, liquid crystal printer,
It can be widely used in electrophotographic application fields such as laser plate making.

[0027]

The present invention will be described in the following examples. Example 1 (1) Formation of Photoconductive Layer An aluminum cylinder of 80φ × 360 mm was used as a base, and a polyamide resin (trade name: Amilan CM-8) was added to the base.
000, manufactured by Toray) was applied by a dipping method to form an undercoat layer having a thickness of 1 μm.

Next, 10 parts by weight of the titanyl phthalocyanine pigment, 10 parts by weight of polyvinyl acetal resin (trade name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 100 parts by weight of cyclohexanone were used for 3 hours in a sand mill using 1φ glass beads. Dispersed. Add 1 part ethyl acetate to this dispersion.
00 parts by weight was added and coated on the undercoat layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.15 μm.

On the charge generation layer, 4-N, N-diethylaminobenzaldehyde diphenylhydrazone 90 is formed.
Parts by weight and 100 parts by weight of a polycarbonate resin (trade name: Novarex, manufactured by Mitsubishi Kasei) dissolved in chlorobenzene are applied, dried at 120 ° C. for 1 hour, and a charge transport layer having a thickness of 12 μm is laminated to function. A separation type electrophotographic photoreceptor was obtained.

(2) Formation of surface protective layer 100 parts by weight of an ultraviolet curable resin (trade name: HILOCK UV, manufactured by Toho Kasei Co., Ltd.) and 20 parts by weight of needle-shaped titanium oxide (made by Ishihara Sangyo, aspect ratio 1:50). Disperse in a stainless steel ball mill for 24 hours and add 5μ to an aluminum substrate.
It is applied to a thickness of m, and an ITO glass substrate is attached to it for 300H.
It was cured by irradiating with ultraviolet rays while applying an AC voltage of z and 20V. The volume resistance of this product is measured to be 3 × 10 ¹⁰ Ωc
It was m.

This dispersion is applied to the electrophotographic photosensitive member and brought into contact with a transparent conductive roll, and 300 Hz, 20 V
3μm by applying UV voltage and curing by UV irradiation
The surface protective layer of 1 was formed to prepare the electrophotographic photoreceptor of the present invention. The surface resistance of this electrophotographic photosensitive member was measured by a surface resistance meter (Daiichi Scientific Co., Ltd.) and found to be 6 × 10 ¹⁵ Ω.

(3) Image evaluation The electrophotographic photosensitive member of the present invention was used as a digital color copying machine CLC500 (semiconductor laser was 680 nm, 3
It was mounted on a device modified to 5 mW and used for image evaluation and durability evaluation. The minimum recording dot was 22 μm, and the residual potential was 50 V, which was excellent and a high quality image was obtained. After running 10,000 sheets, there was no change in the minimum recording dot and residual potential, and the image quality was good.

Comparative Example 1 100 parts by weight of acrylic resin (trade name: Dianal, made by Mitsubishi Rayon) and tin oxide fine powder (made by Ishihara Sangyo) 60
2 parts by weight and 400 parts by weight of dichloroethane in a ball mill
Dispersed for 4 hours and applied to an aluminum substrate, then 5 μm
A thick surface protective layer was obtained. The volume resistance was 2 × 10 ⁸ Ωcm.

This dispersion was applied onto the photoconductive layer used in Example 1 to a thickness of 3 μm. Surface resistance is 6 × 10 ¹¹ Ω
Met. When the image was attached to the CLC500 and evaluated for the image, image deletion and image blurring occurred, and the result was insufficient.

Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the acicular titanium oxide used in the surface protective layer was 25 parts by weight. When the images were evaluated, good images were obtained. Table 1 shows the evaluation results.

Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the acicular titanium oxide used in the surface protective layer was 15 parts by weight. When the images were evaluated, good images were obtained. Table 1 shows the evaluation results.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 1 except that the tin oxide fine powder used in the surface protective layer was 20 parts by weight. When the image was evaluated, an image with poor contrast was obtained.
Table 1 shows the evaluation results.

Comparative Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the surface protective layer was not formed. When the image was evaluated, the initial characteristics were good, but after 10,000 sheets were run, no potential was applied and no image was obtained.

Comparative Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that the thickness of the charge transport layer was 25 μm. However, the surface protective layer was not provided. When the image was evaluated, an image with poor gradation reproducibility was obtained.

[0040]

[0041]

As described above, by using the electrophotographic photosensitive member of the present invention, it is possible to realize high-definition and high-quality recording and to obtain excellent abrasion resistance.

[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]

 1 Photoreceptor 2 Charging Means 3 Exposure Part 4 Developing Means 5 Transfer Means 6 Cleaning Means 7 Pre-Exposure Means 8 Image Fixing Means

Front page continuation (72) Inventor Yuichi Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Etsukaku Sakakibara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Miyazaki Gen 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshiro Kashizaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 72) Inventor Masato Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. An electrophotographic photosensitive member having a photoconductive layer having a thickness of 15 μm or less on a conductive layer, wherein the photosensitive member has a surface resistance of 1 × 10 ¹⁵ Ω or more and a volume resistance in the cross-sectional direction of 1 × 10 ¹² Ω.
An electrophotographic photoreceptor having a surface protective layer having a thickness of 1 cm or less and a thickness of 1 to 10 μm. 2. The surface protective layer has an aspect ratio of 1:10.
The electrophotographic photosensitive member according to claim 1, wherein the needle-shaped fine particles are contained in an amount of 10% by weight or more. 3. The electrophotographic photosensitive member according to claim 2, wherein the acicular fine particles are made of titanium oxide. 4. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1.