JPH05173350A - Electrophotographic sensitive body, electrophotographic apparatus and facsimile provided with the same - Google Patents

Abstract

(57) [Summary] [Object] To provide an electrophotographic photosensitive member having excellent electrophotographic characteristics and a protective layer having excellent environment resistance and abrasion resistance. [Structure] In an electrophotographic photosensitive member having a photosensitive layer and a protective layer on a conductive support, conductive metal oxide fine particles are added to a binder resin containing a curable acrylic monomer whose protective layer has the following structural formula. An electrophotographic photosensitive member, which is formed by coating and curing the dispersed coating liquid on a photosensitive layer.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an electrophotographic photosensitive member having a surface protective layer, an electrophotographic apparatus equipped with the electrophotographic photosensitive member, and a facsimile.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member is required to have required sensitivity, electrical characteristics and optical characteristics in an electrophotographic process in which it is used. Since the surface layer of the photoconductor, that is, the layer which is most isolated from the support, is directly subjected to electrical and mechanical external forces such as corona charging, toner development, transfer to paper, and cleaning treatment. , 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 toner is adhered to the surface layer due to repeated toner development and cleaning, and to this end, it is required to improve the cleaning property of the surface layer.

In order to satisfy the characteristics 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, Japanese Patent Application Laid-Open No. 57-30843 proposes a protective layer in which resistance is controlled by adding a metal oxide as a conductive powder. However, the conventionally used methods have problems in dispersibility of the metal oxide particles in the binder resin, cohesiveness, conductivity when used in the protective layer, and transparency, and unevenness of the protective layer surface. The phenomenon such as image defect due to unevenness, increase in residual potential due to repeated charging, and decrease in sensitivity was likely to occur.

Dispersing a metal oxide in a protective layer for an electrophotographic photoreceptor is to control the electric resistance of the protective layer itself and prevent an increase in residual potential in the photoreceptor during repeated electrophotographic processes. This is the main purpose, while the suitable resistance value of the protective layer for an electrophotographic photoreceptor is 10 ¹⁰ to 10 ^15.
ohm. It has been shown to be cm. However, in the resistance value within the above range, the electric resistance of the protective layer is easily affected by ion conduction, and therefore the electric resistance tends to largely change due to the change of environment. In particular, when the metal oxide is dispersed in the film, the water absorption of the metal oxide surface is high, and therefore, in all environments,
Moreover, it has been very difficult to keep the resistance of the protective layer within the above range when the electrophotographic process is repeated.

Further, in general, when particles are dispersed in a protective layer, in order to prevent scattering of incident light by dispersed particles, the particle size of the particles is smaller than the wavelength of the incident light, that is,
It should be 0.3 μm or less. However, metal oxide particles generally have a strong tendency to aggregate in a resin solution and are difficult to disperse uniformly, and secondary dispersion and sedimentation occur once dispersed, so that a stable dispersion film having a particle size of 0.3 μm or less is obtained. Was very difficult to produce. In order to further improve transparency and conductivity uniformity, it is useful to disperse ultrafine particle powder having a finer particle size (primary particle size of 0.1 μm or less).
Dispersibility and dispersion stability tended to deteriorate. Further, particularly under high humidity, ozone and corona products such as NO _X generated by repeated charging adhere to the surface, which causes a reduction in the surface resistance of the photoconductor, which causes a problem such as image deletion. At present, no layer having satisfactory electrophotographic properties has been obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having durability against abrasion and scratches on the surface caused by rubbing, and yet another object is to provide repeated electrophotography. To provide an electrophotographic photosensitive member capable of maintaining high-quality image quality even under high humidity without lowering the surface resistance due to adhesion of corona products generated in the process. Another object of the present invention is to provide an electrophotographic photosensitive member that exhibits stable electrophotographic characteristics without accumulation of residual potential and reduction of sensitivity.

[0007]

The present invention relates to an electrophotographic photoreceptor having a photosensitive layer and a protective layer on a conductive support, wherein the protective layer is a curable acrylic monomer represented by the following formula (1), a formula ( Conductive metal oxide fine particles are added to a binder resin containing a curable acrylic monomer selected from the group consisting of the curable acrylic monomer represented by 2) and the curable acrylic monomer represented by formula (3). An electrophotographic photosensitive member is characterized in that it is formed by coating and curing the dispersed coating liquid on a photosensitive layer. Formula (1)

[Chemical 4] Formula (2)

[Chemical 5] Formula (3)

[Chemical 6] m, a and b are positive integers

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photosensitive layer and a protective layer on a conductive support.

As described above, the problem when the film in which the conductive metal oxide fine particles are dispersed in the binder resin is used for the protective layer of the electrophotographic photosensitive member is the environmental stability of the fine particles and the electric resistance of the film. It is sex. As a means for solving the above problems, the present inventors have proposed a curable acrylic monomer selected from the group consisting of curable acrylic monomers represented by formula (1), formula (2) and formula (3). The present invention has been accomplished by recognizing that it is very effective to disperse conductive metal oxide fine particles in a binder resin contained therein.

Since the curable acrylic monomer represented by the formula (1), the formula (2) and the formula (3) has a functional group and has a relatively high polarity, the curable acrylic monomer has a relatively high polarity.
By dispersing the conductive metal oxide fine particles in the binder resin containing, it is possible to obtain a coating liquid which is stable and has good dispersibility over time without the formation of secondary particles of dispersed particles. Further, the protective layer formed from this coating solution has high transparency, and a film having excellent environmental resistance such as water resistance and chemical resistance can be obtained.

The method for curing the binder resin containing the specific curable acrylic monomer in the present invention is preferably UV curing from the viewpoint of the curing degree and the uniformity of the interface with the underlying photosensitive layer, but it is also cured by heat. be able to. In the case of ultraviolet curing, it is desirable to use a photoinitiator to accelerate curing. Examples of the photoinitiator include benzophenone, Michler's ketone, thioxanthone, benzoinbutyl ether.
Tellurium, acyloxime ester, dibenzothroben and the like. Although it is desirable to use a radical initiator in the case of performing thermal curing, the conventional radical initiators, for example, p- methoxy benzoyl peroxide, m, m ^'-
Dimethoxy benzoyl peroxide, 2,2 ^'- azobisisobutyronitrile, ^2,2' - dimethyl azobisisobutyrate esters, 4,4 ^'- such as azobis-4-cyano heptanoic acid can be used.

As the binder resin for the protective layer in the present invention, a curable acrylic monomer selected from the group consisting of the curable acrylic monomers represented by the formulas (1), (2) and (3) is used. It may be used alone or in a mixture with another resin. Examples of resins that can be mixed and used include acrylic resins, polyesters, polycarbonates,
Examples thereof include polystyrene, cellulose, polyethylene, polypropylene, polyurethane, epoxy resin, silicone and polyvinyl chloride. Further, a curable monomer that causes copolymerization with the above-mentioned specific curable acrylic monomer.
It is also possible to mix the oligomers.

Examples of the conductive metal oxide in the present invention include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, tin oxide doped with antimony, and oxide. Ultrafine particles such as zirconium can be used. One kind of metal oxide or a mixture of two or more kinds is used. When two or more kinds are mixed, they may be in the form of solid solution or fusion.
The average particle size of the metal oxide is 0.3 μm or less, preferably 0.1 μm or less.

The ratio of the binder resin to the conductive metal oxide fine particles is a value that directly determines the resistance of the protective layer, and the resistance of the protective layer is 10 ¹⁰ to 10 ¹⁵ ohm. Set to be in the range of cm.

In the present invention, additives such as a coupling agent and an antioxidant may be added to the protective layer for the purpose of improving dispersibility, binding property and weather resistance. The protective layer is formed by applying and curing a solution in which a metal oxide is dispersed in the binder resin. The thickness of the protective layer is 0.2 to 7 μm, preferably 0.5 to 5 μm.

The constitution 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 transporting substance in the same layer, or a charge generating layer and a charge transporting layer are laminated on a conductive support. It is either a laminated type.

As the constitution of the laminated type photosensitive layer, there are a constitution in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support, and a constitution in which a charge transport layer and a charge generation layer are conversely laminated in this order. ..

The conductive support may be any one having conductivity, for example, aluminum, copper, chromium, nickel,
Drum or sheet of metal or alloy such as zinc or stainless steel
Molded in the shape of a sheet, laminated with a metal foil such as aluminum or copper on a plastic film, deposited with aluminum, indium oxide, tin oxide on a plastic film, a conductive substance alone or with a binder resin Examples thereof include metal, plastic film, and paper on which a conductive layer is provided by coating.

The charge transport layer comprises a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene or phenanthrene in the main chain or side chain, indol, carbazol.
It is formed by using a coating liquid prepared by dissolving a nitrogen-containing ring compound such as diol, oxadiazol, or pyrazoline, a charge transporting substance such as a hydrazone compound, or a styryl compound in a resin having a film-forming property. Examples of the film-forming resin include polyester, polycarbonate, polystyrene, and polymethacrylic acid ester. The thickness of the charge transport layer is 5 to
The thickness is 40 μm, preferably 10 to 30 μm.

The charge generation layer comprises an azo pigment, pyrenequinone,
Charge generation substances such as quinone pigments such as anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments are used as binder resins such as polyvinyl butyral, polystyrene, polyvinyl acetate, and acrylic resins. It is formed by dispersing and coating the dispersion, or vacuum-depositing the pigment. The thickness of the charge generation layer is 5 μm or less, preferably 0.05 to 3 μm.

An undercoat layer having a barrier function and an adhesive function can be provided between the conductive layer and the photosensitive layer. The undercoat layer is casein, polyvinyl alcohol, nitrocellulose
And ethylene-acrylic acid copolymer, alcohol-soluble amide, polyurethane, gelatin, etc., and the thickness of the undercoat layer is preferably 0.1 to 3 μm.

Since the electrophotographic photoreceptor of the present invention has a high hardness and can form a uniform protective layer having a good dispersibility of metal oxide fine particles, it has no image defects such as unevenness, fog and black spots and is resistant to abrasion. It has extremely high wear resistance and environment resistance, and also has excellent electrophotographic characteristics.

The electrophotographic photosensitive member of the present invention is generally applied to electrophotographic devices such as electrophotographic copying machines, laser printers, LED printers, liquid crystal shutter-type printers, etc. It can be widely applied to devices such as display, recording, light printing, plate making, and facsimile.

The present invention also comprises an electrophotographic apparatus equipped with the electrophotographic photosensitive member of the present invention.

The present invention also comprises an electrophotographic apparatus equipped with the electrophotographic photosensitive member of the present invention and a facsimile having a receiving means for receiving image information from a remote terminal.

Next, an electrophotographic apparatus and a facsimile equipped with the electrophotographic photosensitive member of the present invention will be described. Figure 1
The general construction of a general transfer type electrophotographic apparatus using the drum type photoreceptor of the present invention is shown in FIG. In the figure, reference numeral 1 denotes a drum type photosensitive member as an image bearing member, which is rotationally driven around a shaft 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 with a predetermined positive or negative potential on its peripheral surface by the charging means 2, and then at the exposure section 3 an optical image exposure L (slit exposure Laser
Beam scanning exposure). As a result, electrostatic latent images corresponding to the exposed images 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 from a paper feed unit (not shown) between the photosensitive body 1 and the transfer means 5. And is sequentially transferred onto the surface of the transfer material P that is fed in synchronization with the above. 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 image fixing and printed out as a copy (copy). The surface of the photoreceptor 1 after the image transfer is transferred by the cleaning means 6 to the toner after transfer.
Is removed to obtain a clean surface, and the pre-exposure means 7 removes the charge to repeatedly use it for image formation. Photoconductor 1
A corona charging device is generally widely used as the uniform charging means 2. Also, as the transfer device 5, corona transfer means is generally widely used. As an electrophotographic apparatus, a plurality of constituent elements such as the photoconductor, the developing unit, and the cleaning unit described above are integrally combined as an apparatus unit, and the unit is detachably attached to the apparatus main body. It may be configured. For example, the photosensitive member 1 and the cleaning means 6 may be integrated into one device unit, and the device body may be detachably configured by using guide means such as a rail. At this time, the above-mentioned apparatus unit may be provided with a charging unit and / or a developing unit. In addition, the light image exposure L is applied to an electrophotographic apparatus such as a copying machine or a printer.
When used as a light source, the reflected light or transmitted light from the original is used, or when the original is read and converted into a signal, this signal is used to scan the laser beam, drive the light emitting diode array, or liquid crystal shutter. -It is performed by driving the array or the like. Further, when used as a printer of a facsimile, the light image exposure L becomes an exposure for printing the reception data.

FIG. 2 is a block diagram showing an example of this case. The controller 10 controls the image reading unit 9 and the printer 18. The entire controller 10 is C
It is controlled by the PU 16. The read data from the image reading unit is transmitted to the partner station through the transmission circuit 12. The data received from the partner station is sent to the printer 18 through the receiving circuit 11. Predetermined image data is stored in the image memory. The printer controller 17 controls the printer 18. 13 is a telephone. Line 14
The image (image information from the remote terminal connected through the line) received from the demodulator is demodulated by the receiving circuit 11, and then the CPU 16 performs signal processing of the image information and sequentially stores it in the image memory 15. .. When at least one page of image is stored in the memory 15, the image of that page is stored. The CPU 16 reads out one page of image information from the memory 15 and sends the one page of image information signaled to the printer controller 17. Upon receiving the image information of one page from the CPU 16, the printer controller 17 controls the printer 18 to record the image information of the page. The CPU 16 is a printer
While recording by 18, the next page is being received.
The image is received and recorded as described above.

[0028]

【Example】

Example 1 On an aluminum cylinder (φ30 mm × 260 mm), an alcohol-soluble polyamide (trade name: Amilan CM-80) was used.
00, 10 parts manufactured by Toray Industries, Inc., methoxymethylated 6 nylon (trade name: Resin Resin EF-30T, Teikoku Kagaku Co., Ltd.)
(Prepared) 30 parts by weight dissolved in a mixed solvent of 150 parts of methanol and 150 parts of butanol is applied by dip coating, and at 90 ° C. 1
It was dried for 0 minutes to form an undercoat layer having a film thickness of 1 μm.

Next, 4 parts of the pigment having the following structural formula,

[Chemical 7] 2 parts of butyral resin (trade name 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 were added to the coating liquid for the charge generation layer. Was prepared.
This coating solution was applied onto the undercoat layer by dip coating and dried at 80 ° C. for 15 minutes to form a charge generation layer having a film thickness of 0.15 μm.

Next, a styryl compound 10 having the following structural formula
Department,

[Chemical 8] And polycarbonate (trade name Yupiron Z-20
0, Mitsubishi Gas Chemical Co., Ltd.) 10 parts dichloromethane 2
It was dissolved in a mixed solvent of 0 parts and 60 parts of chlorobenzene, this solution was applied onto the charge generation layer by dip coating, and dried at 120 ° C. for 60 minutes to form a charge transport layer having a thickness of 18 μm.

Next, as a coating liquid for the protective layer, antimony-containing tin oxide fine particles having an average particle diameter of 0.02 μm (trade name T
-1, 100 parts by Mitsubishi Materials Co., Ltd., 100 parts of a curable acrylic monomer represented by the following formula,

[Chemical 9] 0.1 parts of 2-methylthioxanthone as a photoinitiator,
300 parts of toluene was mixed and dispersed in a sand mill for 96 hours to obtain a coating liquid. Using this coating solution, a film was formed on the charge transport layer by spray coating, dried, and then irradiated with ultraviolet rays for 20 seconds with a high pressure mercury lamp at a light intensity of 8 mW / cm ² to form a protective layer having a thickness of 5 μm. Then, an electrophotographic photosensitive member was formed.

The electrophotographic photosensitive member thus prepared was mounted on a copying machine which repeats the process of charging-exposure-developing-transfer-cleaning in a cycle of 1.5 seconds, at 20 ° C.
・ Evaluation of electrophotographic characteristics under normal temperature and humidity of 50%, 1
The image was evaluated under a low temperature and low humidity condition of 0 ° C. and 15% and a high temperature and high humidity condition of 35 ° C. and 85%. As a result, compared with the electrophotographic photosensitive member having no protective layer shown in Comparative Example 1 described later, the sensitivity and residual potential were the same, and an image without unevenness or black spots could be obtained. Moreover, a stable image could be maintained even when the image was repeatedly printed 100,000 times. The results are shown in Table 1.
The dark part potential is the surface potential of the electrophotographic photosensitive member when discharged at a corona discharge voltage +5 KV, and the larger the value, the better the charging ability. The surface potential is 700
The amount of exposure required to attenuate from V to 200 V is shown.

Example 2 In place of the curable acrylic monomer used in Example 1, a curable acrylic monomer of the following formula was used,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 and evaluated.

[Chemical 10]

Example 3 In place of the curable acrylic monomer used in Example 1, a curable acrylic monomer of the following formula was used,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 and evaluated.

[Chemical 11]

Example 4 In place of the curable acrylic monomer used in Example 1, a curable acrylic monomer of the following formula was used,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 and evaluated.

[Chemical 12]

Example 5 In place of the curable acrylic monomer used in Example 1, a curable acrylic monomer of the following formula was used,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 and evaluated.

[Chemical 13]

Example 6 In place of the curable acrylic monomer used in Example 1, a curable acrylic monomer of the following formula was used,
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 and evaluated.

[Chemical 14]

Example 7 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the coating liquid for the protective layer in Example 1 was changed as follows.

Preparation of Coating Liquid for Protective Layer 100 parts of antimony-containing tin oxide fine particles having an average particle diameter of 0.02 μm (described above), a curable acrylic monomer of the following formula
50 parts (abbreviated as first monomer component),

[Chemical 15] 60 parts of a curable acrylic monomer of the following formula (abbreviated as second monomer component),

[Chemical 16] 2-Methylthioxanthone 0.1 as a photopolymerization initiator
Parts and 300 parts of toluene are mixed and the mixture is mixed in a sand mill by 96
It was dispersed for a period of time, and the dispersion was used as a coating liquid for the protective layer.

Example 8 An electrophotographic photosensitive member was prepared in the same manner as in Example 4 except that the curable acrylic monomer of the first monomer component in Example 7 was replaced with a curable acrylic monomer of the following formula. And evaluated.

[Chemical 17]

Example 9 An electrophotography was carried out in the same manner as in Example 7 except that the curable acrylic monomer of the first monomer component and the curable acrylic monomer of the second component in Example 7 were replaced by a curable acrylic monomer of the following formula. A photoconductor was prepared and evaluated.

[Chemical 18]

[Chemical 19]

Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the protective layer was not provided, and the same evaluation was performed.
As a result, as shown in Table 1 below, the initial electrophotographic characteristics were good, but when the durability was increased, the charging ability decreased,
A good image could not be obtained from about 40,000 sheets.

Comparative Example 2 50 parts by weight of antimony-containing tin oxide fine particles (described above) and 100 parts of polycarbonate (described above) with an average particle size of 0.02 μm.
Parts and 300 parts of chlorobenzene were mixed and dispersed by a sand mill for 96 hours to prepare a coating liquid for a protective layer. Using this coating solution, a film was formed by spray coating on the charge transport layer in Comparative Example 1, and dried by heating at 110 ° C. for 1 hour to form a protective layer having a film thickness of 5 μm. It was created and evaluated in the same manner as in Example 1. As a result, as shown in Table 1 below, the initial electrophotographic characteristics were good, but when it was subjected to durability, fog and black spots occurred on the image after about 10,000 sheets, and a good image could not be obtained. It was

The following table shows the evaluation results of the electrophotographic photosensitive members in the above Examples and Comparative Examples.

[Table 1]

[0045]

In the electrophotographic photoreceptor of the present invention, since the conductive metal oxide fine particles are dispersed and contained in the binder resin used in the protective layer, the dispersibility of the metal oxide in the protective layer is good, Excellent electrophotographic properties. Further, since the protective layer has good environment resistance and abrasion resistance, a remarkable effect that a stable image having a good image quality can be obtained even after repeated durability is exhibited.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a general transfer type electrophotographic apparatus.

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Drum type photoconductor as an image carrier (electrophotographic photoconductor of the present invention) 2 Corona charging device 3 Exposure section 4 Developing means 5 Transfer means 6 Cleaning means 7 Pre-exposure means 8 Image fixing means L Optical image exposure P Transfer material having received image transfer 9 Image reading unit 10 Controller 11 Reception circuit 12 Transmission circuit 13 Telephone 14 Line 15 Image memory 16 CPU 17 Printer controller 18 Printer-

Claims (4)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer and a protective layer on a conductive support, wherein the protective layer has the following formula (1).
And a curable acrylic monomer selected from the group consisting of a curable acrylic monomer represented by formula (2), a curable acrylic monomer represented by formula (3), and a curable acrylic monomer represented by formula (3). Using a coating liquid in which conductive metal oxide fine particles are dispersed in a binder resin, coating this on the photosensitive layer,
An electrophotographic photoreceptor, which is formed by curing. Formula (1) Formula (2) Formula (3) Where m, a and b are positive integers 2. The electrophotographic photosensitive member according to claim 1, wherein the protective layer according to claim 1 is formed by coating the protective layer coating liquid and curing the same by irradiation with ultraviolet rays. 3. An electrophotographic apparatus provided with the electrophotographic photosensitive member according to claim 1. 4. A facsimile having an electrophotographic apparatus equipped with the electrophotographic photosensitive member according to claim 1 or 2, and means for receiving image information from a remote terminal. [0001]