JPH0611876A - Electrophotographic sensitive body, electrophotographic device and facsimile provided with the same - Google Patents

Abstract

PURPOSE:To attain excellent slidability and durability against rubbing by forming a protective layer by applying to harden a coating solution made by dispersing an electroconductive metal oxide particulate into a specific curable acrylic monomer on a photosensitive layer. CONSTITUTION:The protective layer is formed by applying to harden the coating solution made by dispersing the electroconductive metal oxide particulate into the curable acrylic monomer expressed by a formula. In the formula, each of R1-R3 is acryloil group or methacryloil group, each of R4 and R5 is acryloil group, metacryloil group or alkyloil group, R6 is acryloil group or hydrogen atom. The curable acrylic monomer which has three or more acryloil group or methacryloil group of a function group has high polarity and by dispersing the electroconductive metal oxide particulate into a binder resin containing the curable acrylic monomer, the stable coating solution is obtained and a film excellent in environmental resistance is formed.

Description

Detailed Description of the Invention

[0001]

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. , 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 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, JP-A-57-30843 proposes a protective layer in which a metal oxide is added as a conductive powder to control the resistance. 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. Image defects due to unevenness, increase in residual potential due to repeated charging, and decrease in sensitivity were 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 m · 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 surface of the metal oxide is high, so that the resistance of the protective layer falls within the above range in the entire environment and when the electrophotographic process is repeated. It has been very difficult to keep inside.

In general, when particles are dispersed in a protective layer, in order to prevent scattering of incident light due to 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, in general, metal oxide particles have a strong tendency to aggregate in a resin solution and it is difficult to uniformly disperse them, and secondary dispersion and sedimentation occur once dispersed, so that a dispersion film with a particle size of 0.3 μm or less is stable. Was very difficult to produce. In order to further improve transparency and conductivity uniformity, it is useful to disperse ultrafine particle powder (primary particle diameter of 0.1 μm or less) having a smaller particle diameter.
The dispersibility and dispersion stability tended to deteriorate. More particularly in high humidity, causing a decrease in the surface resistance of the photosensitive member by ozone generated by repeatedly charging and corona products such as NO _X adheres to the surface, still protected by problems such as image flow occurs At present, no layer having satisfactory electrophotographic characteristics has been obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member which is excellent in slipperiness and has durability against abrasion and scratches on the surface caused by rubbing. The object is to provide an electrophotographic photosensitive member capable of maintaining high-quality image quality even under high humidity without a reduction in surface resistance due to adhesion of corona products generated in a repeated electrophotographic process, and yet another object is: An object of the present invention is to provide an electrophotographic photosensitive member which exhibits stable electrophotographic characteristics without accumulation of residual potential and deterioration of sensitivity in repeated electrophotographic processes.

[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 conductive to the curable acrylic monomer represented by the following general formula (1). It is composed of an electrophotographic photosensitive member characterized by being formed by applying a coating liquid in which metal oxide fine particles are dispersed and coating and curing it on a photosensitive layer.

General formula (1)

[0009]

[Outside 2] In the formula, R _{1 to} R ₃ represent an acryloyl group or a methacryloyl group, R ₄ and R ⁵ represent an acryloyl group, a methacryloyl group or an alkyloyl group, and R ₆ represents an acryloyl group, a methacryloyl group, an alkyloyl group or a hydrogen atom. Show.

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 that the dispersibility of the fine particles and the electrical resistance of the film are environmentally stable. It is sex. The present inventors have recognized that it is very effective to disperse conductive metal oxide fine particles in the curable acrylic monomer represented by the general formula (1) as a means for solving the above-mentioned problems. The invention was reached.

Since the curable acrylic monomer represented by the general formula (1) has three or more acryloyl groups or methacryloyl groups which are functional groups, it has a relatively high polarity. By dispersing the conductive metal oxide fine particles in the coating resin, secondary particles of dispersed particles are not formed, and a coating liquid having stable dispersibility and stable over time can be obtained. 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.

As the curable acrylic monomer represented by the general formula (1), a curable acrylic monomer having three or more acryloyl groups or methacryloyl groups may be used alone, or two or more curable acrylic monomers having different acryloyl groups or methacryloyl groups may be used. In general, a cured film formed of a compound having a reactive functional group may have a higher hardness as the number of the functional groups increases, and thus the surface of the cured film may be worn or scratched by rubbing. Is less likely to occur. However, the higher the number of functional groups, the higher the shrinkage rate of the film upon curing, which may cause the occurrence of cracks in the lower photosensitive layer of the electrophotographic photoreceptor, and thus the hardness is sufficient and the shrinkage rate is low. It was difficult to form a small cured protective layer. In that respect, the curable acrylic monomer represented by the general formula (1) has good compatibility with each other having different numbers of functional groups, and two or more kinds of monomers can be mixed and used at an arbitrary ratio, and the number of functional groups is different. It is also possible to control the shrinkage rate by mixing the materials, and it is possible to reduce the shrinkage rate without substantially reducing the strength of the cured film.

The binder resin containing the curable acrylic monomer represented by the general formula (1) is preferably cured by ultraviolet light in terms of the degree of curing and the uniformity of the interface with the underlying photosensitive layer, but it is also cured by heat. Can be made. 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, benzoin butyl ether, acyloxime ester, dibenzothroben and the like. When performing heat curing, it is desirable to use a radical initiator, but as a normal radical initiator,
For example, p-methoxybenzoyl peroxide, m, m'-dimethoxybenzoyl peroxide, 2,2'-azobisisobutylnitrile, 2,2'-azobisisobutyric acid dimethyl ester, 4,4'-azobis-4-cyanoheptanoic acid and the like can be used.

As the binder resin for the protective layer in the present invention, the curable acrylic monomer represented by the general formula (1) may be used alone or in combination with other resins. Examples of the resin that can be mixed and used include acrylic resin, polyester, polycarbonate, polystyrene,
Examples thereof include cellulose, polyethylene, polypropylene, polyurethane, epoxy resin, silicone, polyvinyl chloride and the like. Further, it is also possible to mix a curable monomer and an oligomer which cause copolymerization with the curable acrylic monomer represented by the general formula (1).

Examples of the conductive metal oxide in the present invention include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide and zirconium oxide. Fine particles can be used. The metal oxides may be used alone or in combination of two or more. 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 so that it is 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 the charge generating substance and the charge transporting substance in the same layer, or the charge generating layer and the 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 generating 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 generating layer are conversely laminated in this order. .

The conductive support may be any one having conductivity, such as aluminum, copper, chromium, nickel,
Drum or sheet shaped metal or alloy such as zinc, stainless steel, laminated metal foil such as aluminum or copper on plastic film, aluminum, indium oxide, tin oxide etc deposited on plastic film, conductive Examples of the material include a metal, a plastic film, and paper in which a conductive substance is applied alone or together with a binder resin to form a conductive layer.

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, a nitrogen-containing ring compound such as indole, carbazole, oxadiazole or pyrazoline, or a hydrazone compound. , A styryl compound or another charge transport material is dissolved in a resin having film-forming properties. Examples of the film-forming resin include polyester, polycarbonate, polystyrene, polymethacrylic acid ester and the like. 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,
Dispersing charge generating substances such as quinone pigments such as anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments into binder resins such as polyvinyl butyral, polystyrene, polyvinyl acetate, and acrylic resin. It is formed by coating this 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 subbing layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, alcohol-soluble amide, polyurethane, gelatin or the like. The thickness of the undercoat layer is preferably 0.1 to 3 μm.

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

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

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

Further, the present invention comprises an electrophotographic apparatus provided 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 schematic structure of an electrophotographic apparatus using the electrophotographic photosensitive member 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. The photosensitive member 1 is uniformly charged at its peripheral surface by a charging unit 2 at a predetermined positive or negative 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). 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
Next, the toner is developed by the developing means 4, and the toner developed image is fed by the transfer means 5 from a paper feeding portion (not shown) between the photoconductor 1 and the transfer means 5 in synchronism with the rotation of the photoconductor 1. The images are sequentially transferred onto the surface of the transfer material P. 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 unit 6 to remove the transfer residual toner, and the pre-exposure unit 7 removes the charge to repeatedly use the image. Uniform charging means 2 for photoconductor 1
For this reason, a corona charging device is generally widely used.
Also, as the transfer device 5, corona transfer means is 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. 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-mentioned apparatus unit may be configured with a charging means and / or a developing means. Also, light image exposure L
When an electrophotographic device is used as a copying machine or a printer, it uses reflected light or transmitted light from the original, or scans the laser beam and drives the light emitting diode array by this signal according to the reading signal of the original. , Or by driving a liquid crystal shutter array. Further, when used as a printer for a facsimile, the light image exposure L becomes an exposure for printing the received data.

FIG. 2 shows an example of a block diagram of a facsimile having the electrophotographic photosensitive member of the present invention. The controller 10 controls the image reading unit 9 and the printer 18. The entire controller 10 is controlled by the CPU 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. The image received from the line 14 (image information from a remote terminal connected via the line) 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 an image of at least one page is stored in the memory 15, the image of that page is stored. CPU1
Reference numeral 6 reads the image information of one page from the memory 15 and sends the image information of one page signaled to the printer controller 17. The printer controller 17 is a CPU
When receiving the image information of one page from 16, the printer 18 is controlled to record the image information of the page. The CPU 16 is receiving the next page while the printer 18 is recording. The image is received and recorded as described above.

[0031]

【Example】

Example 1 An alcohol-soluble polyamide (trade name: Amilan CM-80) was placed on an aluminum cylinder (φ30 mm × 260 mm).
00, 10 parts by Toray Co., Ltd., methoxymethyl or 6 nylon (trade name: Resin Resin EF-30T, Teikoku Kagaku Co., Ltd.)
(Preparation) 30 parts of methanol 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 a disazo pigment having the following structural formula,

[0033]

[Outside 3] 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 was added to prepare a coating liquid for a charge generation layer. did.
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 thickness of 0.15 μm.

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

[0035]

[Outside 4] And polycarbonate (trade name Iupilon 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 structural formula,

[0037]

[Outside 5] 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 is formed by spray coating on the charge transport layer, dried, and then irradiated with ultraviolet light for 20 seconds with a high pressure mercury lamp at a light intensity of 8 mW / cm ² to form a protective layer with a thickness of 5 μm. Then, an electrophotographic photoreceptor was prepared.

The electrophotographic photosensitive member thus prepared is mounted on a copying machine which repeats the process of charging, exposing, developing, transferring and cleaning in a cycle of 1.5 seconds, and sets it at 20.degree.
・ Evaluation of electrophotographic characteristics under normal temperature and normal humidity (N / N) of 50%, low temperature and low humidity (L / L) of 10 ° C and 15%, and 3
Image evaluation was performed under high temperature and high humidity (H / H) of 5 ° C. and 85%, and further, repeated image development was performed 100,000 times under normal temperature and normal humidity. As a result, as 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, 10
It was possible to maintain a stable image even when the image was repeatedly printed ten thousand times. The results are shown in Table 1. The dark portion 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 sensitivity is indicated by the amount of exposure required to reduce the surface potential from 700V to 200V.

Examples 2 and 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the structure of the curable monomer in the coating liquid for the protective layer in Example 1 was changed as follows. , Evaluated.

Structure of curable monomer Example 2

[0041]

[Outside 6]

Example 3

[0043]

[Outside 7]

Example 4 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the coating solution 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 (above) having an average particle diameter of 0.02 μm, 50 parts of a curable acrylic monomer having the following structural formula,

[0046]

[Outside 8] Further, 60 parts of a curable acrylic monomer having the following structural formula,

[0047]

[Outside 9] 2-Methylthioxanthone 0.1 as a photopolymerization initiator
Parts and 300 parts of toluene are mixed to obtain 96 by a sand mill device.
The dispersion was carried out for a time, and the dispersion was used as a coating liquid for the protective layer.

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 electrophotographic characteristics were good at the initial stage, but when it was subjected to durability, the chargeability was lowered and a good image could not be obtained from about 40,000 sheets.

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

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

[0051]

[Table 1]

[0052]

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. Furthermore, since the protective layer has good environment resistance and abrasion resistance, a remarkable effect that a stable image with good image quality can be obtained even after repeated durability is exhibited.

[Brief description of drawings]

FIG. 1 is an example of a schematic configuration diagram of an electrophotographic apparatus having an electrophotographic photosensitive member of the present invention.

FIG. 2 is an example of a block diagram of a facsimile having the electrophotographic photosensitive member of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic photosensitive member (electrophotographic photosensitive member of the present invention) 2 Corona charging device 3 Exposure part 4 Developing means 5 Transfer means 6 Cleaning means 7 Pre-exposure means 8 Image fixing means L Optical image exposure P Transfer material which received image transfer 9 image reading unit 10 controller 11 receiving circuit 12 transmitting circuit 13 telephone 14 line 15 image memory 16 CPU 17 printer controller 18 printer

Claims (5)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer and a protective layer on a conductive support, wherein the protective layer has conductive metal oxide fine particles dispersed in a curable acrylic monomer represented by the following general formula (1). An electrophotographic photoreceptor, which is formed by applying a coating liquid on a photosensitive layer and curing the coating liquid. General formula (1) In the formula, R _{1 to} R ₃ represent an acryloyl group or a methacryloyl group, R ₄ and R ₅ represent an acryloyl group, a methacryloyl group or an alkyloyl group, and R ₆ represents an acryloyl group, a methacryloyl group, an alkyloyl group or a hydrogen atom. . 2. The coating liquid according to claim 1, wherein
The electrophotographic photosensitive member according to claim 1, which contains at least two or more different functional groups of the curable acrylic monomer represented by the general formula (1). 3. 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. 4. An electrophotographic apparatus provided with the electrophotographic photosensitive member according to claim 1. 5. A facsimile having an electrophotographic apparatus equipped with the electrophotographic photosensitive member according to claim 1 and means for receiving image information from a remote terminal.