JP2003156972A - Photoreceptor for electrophotography and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor for electrophotography in which quietness of electrifying noise generated when carrying out image formation by applying DC voltage superposed with AC voltage is improved and which can be reproduced and reused. SOLUTION: In the photoreceptor for electrophotography incorporating with damping material, 3 layers of a supporting body provided with a spring function, the damping material and a covering material are contained in at least the damping material and the supporting body with the spring function, the damping material and the covering material are constituted in this order from the side facing the center of the photoreceptor for electrophotography.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoconductor and an image forming apparatus. More specifically, the present invention relates to an electrophotographic photoreceptor including a vibration damping material having a specific structure that applies a DC voltage with an AC voltage superimposed on a charging member to suppress a charging sound generated when the photoreceptor is charged. And an image forming apparatus in which the electrophotographic photoconductor is mounted.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image using an indirect electrophotographic method such as a facsimile, a laser beam printer and an electrophotographic copying machine, an electrophotographic photoreceptor (hereinafter simply referred to as "photoreceptor") is used. A charging member, an image exposure system, a developing device, a transfer device, a separating device, a cleaning device, a static eliminator, etc. are arranged at the center, and an image is formed on the photoconductor by operating each device in order. At the time of image formation, the photosensitive member is charged with a charging member from -400 to -800.
V charging (charging) is performed.

A charging method generally used at present is to use a metal wire such as a tungsten wire or a nickel wire having a diameter of 40 to 80 μm, which is mounted in a shield case over the lengthwise direction of the photoconductor. Corona charging method of applying a high voltage of about 4500 to -6500V, 10 ² to 10 ⁸ Ω · cm
For a roller-shaped or brush-shaped charging member having a certain resistance, a DC voltage of -1200 to -2000 V, or a DC voltage of -600 to -1000 V, 1000 to 20
There is a contact charging method in which a voltage in which an AC voltage of 00V / 500 to 2500 Hz is superimposed is applied. Further, there is a non-contact charging method in which a charging member is disposed at a distance of about 30 to 250 μm from the photoconductor and a voltage is applied.

In the contact charging method, a sufficiently practical image can be obtained with only the DC voltage, but in the non-contact charging method, charging unevenness is likely to occur with the DC voltage alone. Therefore, the applied voltage is a DC voltage superimposed with the AC voltage. It is desirable to do so. This improves the environmental stability of charging,
Charging is performed well even in a high humidity environment of 80 to 90% RH, and image nonuniformity such as potential unevenness and halftone unevenness due to unevenness of the charging member, the photosensitive member, and minute unevenness of the member occurs. Be improved.

Further, since a high voltage is applied in the corona charging method, a high concentration of ozone of about 10 ppm is generated, which causes environmental problems due to ozone odor. On the other hand, the contact charging method is an environmentally advantageous charging method because the applied voltage is low and ozone generation is extremely low at 0.1 ppm or less. In recent years, in the contact charging method, a DC voltage superimposed with an AC voltage is applied. The charging method is often used.

However, when a direct current voltage on which an alternating current voltage is superposed is applied to the charging device, the applied voltage becomes high due to the superposition of the alternating current voltage, and due to low resistance pollutants such as ozone and nitrogen oxides, compared to the direct current voltage. In addition to the phenomenon that the image quality is deteriorated, there is a noise problem that a charging sound that is a high-frequency sound that is offensive to the ear is generated. The charging sound is not a problem when applied with a DC voltage, but when it is an AC voltage, it is a vibrating current, so it causes vibration on the photoconductor, and the vibration at this time causes a continuous noise called keen in the ear. Sounds like. The charging sound may become lower or higher depending on the frequency of the applied voltage, but the frequency band used for charging is often between 1000 and 2000 Hz, which is a very sensitive frequency band to the human ear.

As means for improving this charging sound, a method of thickening the support of the photosensitive member, inserting a damping material (filler) inside the drum-shaped photosensitive member, and taking measures against the charging sound from the charging member side Etc. have been proposed.

These methods are to mechanically or physically improve the vibration of the photosensitive member, that is, the reverberation when the photosensitive member is hit by the electric charge at the time of discharge, and there are some cases as shown below. There is. As a method of inserting a filler into the inside of the drum-shaped photoconductor to improve the generation of charging noise at the time of charging, for example, Japanese Patent Laid-Open No. 5-197321 discloses that the total weight / total volume of the photoconductor is 0.65 g. / cm ³ or more, it is disclosed to be inserted inside a density 2.0 g / cm ³ or more rigid of the photosensitive member. In this disclosed example, the generation of charging noise is improved by inserting a rigid body such as cylindrical aluminum, brass, cement, gypsum, ceramics or natural rubber having the above-mentioned characteristics into the photoconductor. To improve the adhesion to the photoconductor, cover the filler with an elastic material such as urethane rubber or chloroprene rubber of about 1 to 5 mm, and use a cyanoacrylate or epoxy adhesive as necessary after mounting. It is something that is fixed.

In this case, the weight of the filler and the close contact with the inner wall of the photosensitive member are important for suppressing the charging noise. Here, a high-weight filling material is used, and adhesion is achieved by using an elastic body or an adhesive. However, brass, ceramics, natural rubber, etc. are materials with a relatively high damping effect,
Although it is a material having a high density, if an elastic body having a high coefficient of friction such as rubber is used to fix them, it becomes difficult to insert and remove, and it is very disadvantageous in terms of reuse of members. Moreover, when an adhesive is used, it cannot be taken out. Further, when a metal lot of brass or copper having a large mass is built in and the gear of the photoconductor is driven, the vibration damping effect is large, but the resin flange of the photoconductor and the drive gear may be worn away. Furthermore, when using the non-contact charging method that charges the photosensitive member several tens of μm away, compared to the contact charging method, the damping effect due to the load of the charging member becomes lower and the hazard becomes severer. However, there is a problem that the vibration damping effect becomes insufficient because the propagation of the wave cannot be blocked.

Further, JP-A-11-184308 discloses a columnar shape of two or more elastic bodies (O-rings) and a plastic having a specific gravity of 1.5 or more (polybutylene terephthalate resin containing 20% or more of glass fibers). It is disclosed that a filler composed of a member is inserted into the photoreceptor. In this disclosed example, the charging material is held in the photoconductor with an O-ring, and the charging noise is suppressed by pressing the O-ring against the photoconductor and increasing the weight of the filling material. As the weight increases, the suppression effect works, but the part where the O-ring is in contact with the inner wall of the photoconductor is in close contact, but the other parts are hollow, so the vibration suppression effect is insufficient and as expected. There is a problem in that it is difficult to obtain results.

Further, Japanese Patent Laid-Open No. 2000-321929 discloses that a resin cylindrical member having a metal spring incorporated therein is inserted and fixed to the inner wall of the photosensitive member by pressing force. In this disclosed example, a metal spring made of, for example, a 0.5 mm stainless steel plate is attached to the inside of a resin-made cylindrical member having a notch, and the member is inserted into the photoconductor and pressure-bonded to the inner wall of the photoconductor. It achieves the task. However, even with this method, since the resin material is relatively apt to vibrate even when it is pressed against the inner wall of the photoreceptor, the absorption of the charging sound is insufficient and the desired effect cannot be obtained. Moreover, since the resilience of the resin becomes weaker as the thickness becomes thicker, it is necessary to use a resin having a thin plate thickness, but as the thickness becomes thinner, the vibration damping effect becomes weaker and the desired effect cannot be obtained. By using a metal spring with a thickness of about 0.5 mm, the pressing effect is high and it can be brought into close contact with the inner wall of the photoconductor, but since it has a large repulsive force, it can be rolled, that is, cylindrical. There is a problem that the roundness of the photoconductor may be deteriorated depending on the method.

As another method for improving the charging noise,
There is a method of increasing the vibration damping effect by increasing the thickness of the photoconductor substrate. For example, Japanese Patent Laid-Open No. 2000-19761 discloses
It is described that a spigot process is applied to both ends of the base of the photoconductor to use a photoconductor support having a thickness other than the spigot of 1.9 mm or more. Also, Japanese Patent Laid-Open No. 2000-155
In Japanese Patent Publication No. 500, the deposition density of the photoreceptor is 0.6 g / cm.
³ above, it has been described that to obtain a damping effect by a 2.0 g / cm ³ or less. In the above two examples, the charging noise is suppressed by making the thickness of the central portion thicker than the portion where the flange of the double-sided photoreceptor support is mounted. When the thickness of the photoreceptor support is increased, the sound is suppressed because it becomes rigid and the sound waves in the layer are absorbed and the sound is reduced. However, aluminum used for the photoreceptor support material has a good sound propagation, and has a low absorption coefficient, so that it has a property of easily resonating. Further, as compared with the contact charging method, the charging by the non-contact charging member having a gap of about several tens of μm between the photoconductor and the charging member raises the hazard, so that the noise is more likely to occur and the expected effect can be obtained. There is a drawback that cannot be done.

The charging sound is a phenomenon that occurs when the photoconductor is struck and vibrated by an alternating voltage (vibration voltage) applied to the charging member, and it is more conditional when the charging member is far from the photoconductor. However, since it becomes severe, the charging noise tends to be loud. Changing the frequency of the AC voltage to a range that is less offensive than the practical frequency range has a high possibility that the charging itself will not be established, and therefore it is easier to take effect on the photoconductor side. The external cover attached to the image forming apparatus has an effect of blocking the sound from leaking to the outside, and is hard to be heard by the driving sound. However, if the noise is high, the sound insulating effect is not sufficient and the charging member is not affected. Since the frequency band of the applied AC voltage in a suitable range is extremely sensitive to the human ear, it is absolutely necessary to take measures against the noise of the charging sound.

Although it is appropriate to take countermeasures against the charging sound on the side of the photoconductor, the support material of the photoconductor, the thickness, the type of material to be filled inside, the single member or the composite member, or the combination of those members. It largely depends on the degree of adhesion to the inner wall of the photoconductor, the material and thickness of the flanges fixed to both ends of the photoconductor, the fixing method, and the like. Further, the way of feeling greatly varies depending on the frequency of the AC voltage applied to the charging member and the peak value of the voltage.

When the damping material is inserted into the photosensitive member, even if the damping material has a sufficient damping effect, if the damping material is cooled and the damping material contracts, Since a gap is generated between the vibration damping material and the inner wall of the photoconductor, the vibration damping effect of the photoconductor becomes difficult to work sufficiently. Therefore, the damping material is generally fixed with an adhesive. The damping effect is achieved by using adhesives and bonding it to the inner wall of the photoconductor without gaps.
The vibration damping material and the photoconductor are integrated to obtain a great vibration damping effect. However, when the local adhesion is limited or when the adhesion is insufficient, voids are generated, and it is difficult to obtain the expected vibration damping effect. When an adhesive is used for the photoconductor, it is possible to enhance the vibration damping effect, but it becomes difficult to separate the vibration damping material and the photoconductor, so it is possible to reuse the vibration damping material and regenerate the photoconductor. Will be a problem above. Even if it could be separated, the adhesive is attached to the inner wall of the photoconductor, which makes it difficult to recycle, and the damping material itself is also difficult to reuse, which is environmentally and resource-saving. The problem is big.

[0016]

SUMMARY OF THE INVENTION The present invention solves the above conventional problems, and An electrophotographic photosensitive member capable of effectively improving the quietness of a charging sound generated when an image is formed by applying a DC voltage with an AC voltage superimposed on a charging member. 2. Quietness of the charging noise is achieved by incorporating a damping material with a specific configuration in the photoconductor, and the damping material and the photoconductor can be easily separated, reusable and reusable, and highly durable. ,
Environmentally friendly resource-saving and energy-saving photoconductor for electrophotography with long life. 3. An image forming apparatus comprising a non-contact charging member and these highly durable electrophotographic photoreceptors for charging by applying a DC voltage superimposed DC voltage to the non-contact charging member. The purpose is to provide.

[0017]

As a result of various studies on methods for solving such problems, the present inventors have found that a DC voltage in which an AC voltage is superposed on a charging member which is in contact with or in close proximity to a photoconductor. The charging sound generated when the photosensitive member is charged by applying a voltage occurs because the photosensitive member vibrates due to an AC voltage (oscillating voltage). Therefore, in order to prevent or suppress this charging noise, a rigid body which does not vibrate the photosensitive body may be used, but it is not practical because of cost, heavy weight, and heavy load on other members. When a damping material that suppresses charging noise is inserted into a drum-shaped photoconductor, it is important that the damping material is sufficiently adhered or adhered to the inner wall of the photoconductor. Further, the present invention has been completed by focusing on the fact that if there is a gap between the inner wall of the photoconductor and the damping material, vibration locally occurs in the region of the gap and the suppressing effect is reduced.

That is, the invention according to claim 1 of the present invention is an electrophotography in which a damping material that is charged to a surface potential required for image formation by applying a DC voltage superposed with an AC voltage to a charging member is incorporated. In the photoconductor for electrophotographic use, the vibration damping material includes at least three layers of a support having a spring function, a vibration absorbing material, and a covering material, and the support having a spring function in order from the side facing the center of the electrophotographic photoconductor, the vibration An electrophotographic photoreceptor comprising an absorber and a coating material in that order.

According to a second aspect of the present invention, in the electrophotographic photosensitive member according to the first aspect of the invention, the support having a spring function is a phosphor bronze plate or a stainless plate.

According to a third aspect of the present invention, in the electrophotographic photosensitive member according to the second aspect, a sheet-shaped member is formed over the entire surface of the phosphor bronze plate or the stainless plate opposite to the surface where the vibration absorbing material is attached. It is characterized by being attached.

The invention according to claim 4 is the electrophotographic photoreceptor according to claim 1, wherein the vibration absorbing material is butyl rubber.

According to a fifth aspect of the invention, in the electrophotographic photoreceptor of the first aspect of the invention, the coating material is a nonwoven fabric or a resin film.

According to a sixth aspect of the present invention, a direct-current voltage having an alternating-current voltage superimposed thereon is applied to a charging member arranged in a very close proximity to form a first charge-transporting layer and a second charge-transporting layer in which inorganic fine particles are dispersed. Forming the latent image on the electrophotographic photosensitive member of the invention according to any one of claims 1 to 5, and then performing image formation using an electrophotographic method of forming a latent image by image exposure. And an image forming apparatus.

According to a seventh aspect of the present invention, there is provided an image forming apparatus according to the sixth aspect, wherein the electrophotographic photoreceptor is 30
It is characterized in that it is charged by a non-contact charging member that is separated by up to 200 μm.

The invention according to claim 8 is the electrophotography according to any one of claims 1 to 5, wherein a first charge transport layer and a second charge transport layer in which inorganic fine particles are dispersed are formed. A charging member, an image exposure system, a developing device, a transfer device, a separating device, and a cleaning device are arranged in this order around the photoconductor for electrophotography, and a DC voltage in which an AC voltage is superimposed is applied to the charging member to obtain the electrophotographic image. An image forming apparatus is characterized in that an image is formed by charging a photoconductor for charging.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an electrophotographic photoreceptor having a built-in vibration damping material that is charged to a surface potential required for image formation by applying a DC voltage superposed with an AC voltage to a charging member. The vibration damping material includes at least three layers of a support having a spring function, a vibration absorbing material, and a coating material, and the support having the spring function, the vibration absorbing material, and the coating material are arranged in this order from the side facing the center of the electrophotographic photoreceptor. It is characterized in that it is configured in the order of.

In a preferred embodiment, the support having a spring function is a phosphor bronze plate. In another preferred embodiment, the support having a spring function is a stainless plate.

In another preferred embodiment,
It is characterized in that the sheet-shaped member is stuck over the entire surface of the phosphor bronze plate on the side opposite to the surface where the vibration absorber is stuck. Another preferred embodiment is characterized in that the sheet-shaped member is attached over the entire surface of the stainless steel plate on the side opposite to the attachment surface of the vibration absorber.

In another preferred embodiment,
The vibration absorbing material is butyl rubber. Further, preferably, butyl rubber is at least 1
One or more layers are formed.

In another preferred embodiment,
The coating material is a non-woven fabric or a resin film.

In another preferred embodiment,
The damping material is fixed so as to be in close contact with the inner wall of the electrophotographic photosensitive member.

In another preferred embodiment,
Butyl rubber is stretched over almost the entire surface of a support having a spring function.

In another preferred embodiment,
It is characterized in that the butyl rubber is completely covered with a coating material from the end face to the end of the support. Yet another preferred embodiment is characterized in that the end face of the butyl rubber is covered with a coating material from the end portion of the support, and the end portion of the coating layer is bonded to the support with an adhesive. is there.

In another preferred embodiment,
The photoreceptor used for image formation is a layer in which an undercoat layer, a charge generation layer, a first charge transport layer are sequentially formed on a support, and a second charge transport layer in which inorganic fine particles are dispersed is further formed. It is characterized by having a configuration. More preferably, the inorganic fine particles dispersed in the second charge transport layer are alumina or titanium oxide, and the dispersed amount of the inorganic fine particles is 10 to 40% by weight in the second charge transport layer. It is a feature.

In another preferred embodiment, the present invention applies a direct current voltage superposed with an alternating current voltage to a charging member which is disposed in close proximity, and incorporates a vibration damping material including at least three layers, and The image forming apparatus is characterized in that after the electrophotographic photoreceptor on which the charge transport layer is formed is charged, an image is formed using an electrophotographic method in which a latent image is formed by imagewise exposure.

From the electrophotographic photoreceptor, preferably 30 μ
It is characterized in that it is charged by a non-contact charging member separated by m to 200 μm.

In another preferred embodiment, the present invention incorporates a damping material containing at least three layers, and
Focusing on the electrophotographic photoreceptor having the second charge transport layer formed on the first charge transport layer, in order, a charging member, an image exposure system,
A developing device, a transfer device, a separating device, and a cleaning device are arranged, and a DC voltage in which an AC voltage is superimposed is applied to a charging member to charge the electrophotographic photosensitive member to form an image. The image forming apparatus.

An example of a copying process in which the present invention is used will be described with reference to the schematic diagram of FIG. In the copying process in which the present invention is used, an image is formed by an indirect electrophotographic method, and mainly the organic photoconductor 1 is provided with a charging member 2, an image exposure system 3, a developing device 4, a transfer device 5, and a separating device 6. An image is formed by arranging a cleaning device 7 (the cleaning device 7 is configured by adding a cleaning blade 7a or a cleaning brush 7b) and operating them in order. A vibration damping material 100 (basically consisting of a support having a spring function, a vibration absorbing material, and a coating material) is incorporated in the photoconductor 1 and is attached to and fixed to the inner wall of the photoconductor. To be done.

At the time of image formation, the photosensitive member is charged to a surface potential of about -500 to -800 V by applying a DC voltage with an AC voltage superimposed on the charging roller forming the charging member 2. At both ends of the charging roller, a width of 5 to 1 is set so that the charging roller and the photoconductor are separated from each other by 30 to 150 μm.
A spacer member made of a 0 mm polyester film, a polyethylene terephthalate film, a fluororesin film or the like is attached. The spacer member of the charging roller is in contact with the photoconductor, and charges the photoconductor by its own weight, either subordinately rotating with the photoconductor or rotating via a gear. After the photoconductor is charged, the original image read by CCD (charge coupled device) or the digital signal sent from personal computer is converted into the optical signal of LD or LED device, and convex lens, polygon mirror, cylindrical An image narrowed down to a dot diameter of about 30 to 70 μm is irradiated onto the surface of the photoconductor as image exposure by the image exposure system 3 such as a lens, and a potential difference between light and dark is generated to form an electrostatic latent image.

The electrostatic latent image is visualized by a developing device 4 containing a one-component developer or a two-component developer consisting of toner and carrier, and then transferred to a copy sheet 9 by a transfer device 5 to separate it. The copy sheet is separated from the photoconductor 1 by 6 and sent to the fixing device 8 to form a hard copy. on the other hand,
The residual toner on the photoconductor after the copy paper is separated is cleaned by the cleaning device 7, and a series of copying cycles is completed.

Next, the photosensitive member used in the present invention will be described. The organic photoconductor used in the present invention is preferably a function-separated type photoconductor having a structure in which a charge transport layer is disposed on the surface layer as shown in FIG. It is composed of two layers of a charge transport layer (hereinafter also referred to as "charge transport layer 1") and a second charge transport layer (hereinafter also referred to as "charge transport layer 2").

The charge transport layer 1 is the same as the conventional photosensitive layer having a three-layer structure, but the charge transport layer 2 is an extension of the charge transport layer 1, satisfies the electrical characteristics and optical characteristics, and has high durability. 2 to 10 μm, in which an appropriate amount of inorganic fine particles such as alumina (aluminum oxide) or titanium oxide is added to achieve
m is a photosensitive layer.

The conductive support of the photoconductor may be any one satisfying various electrical, mechanical, and chemical characteristics, such as metal such as stainless steel, copper, and brass, compressed paper, resin, or glass. A conductive layer formed by vapor deposition or sputtering of gold, aluminum, platinum, chromium or the like, or a conductive layer in which fine particles of carbon, tin or the like are dispersed may be applied. For example, commonly used methods for processing the surface of aluminum include cutting, honing, blasting, etc. After cutting to the target outer diameter dimension, the surface is further processed by superfinishing, mirror finishing, etc. Roughness 0.1 to 10 μm
It is processed to a certain extent. The electric resistance is a volume specific resistance, and there is no problem as long as it has a value of 10 ⁶ Ω · cm or less. The shape of the conductive support is drum-shaped, and the wall thickness depends on the diameter and the material, but when aluminum of JIS3003 is used, for example, it may be about 0.5 to 5 mm, and the diameter of 24 to 0.8 to 80 mm photoreceptor
A conductive support having a thickness of about 3 mm can be favorably used.

The undercoat layer maintains the charging property by preventing charge injection from the conductive support, prevents latent image disturbance due to irregular reflection in the photosensitive layer of digitally exposed image exposure, prevents moiré, conductive support, charge. It is formed in order to improve coatability and adhesiveness of both layers of the generating layer. The undercoat layer is an alumina vapor deposition film, and in the case of a dispersion system, a metal oxide such as TiO ₂ or SnO ₂ is dispersed in an alkyd resin, an alkyd-melamine resin, polyvinyl alcohol, casein, etc. 1 using dipping method, spray method, ring coating method, etc.
Apply to a thickness of -10 μm. If the undercoat layer is too thick, the residual potential is likely to increase repeatedly, and conversely if it is too thin, charge injection from the conductive support is likely to occur and the SN ratio deteriorates, and noise (black spots, background, etc. This leads to an increase in dirt and the like. Usually, an undercoating layer having a volume resistance of about 10 ⁹ to 10 ¹² Ω · cm is uniformly formed with a film thickness of 3 to 8 μm, or injection of holes from a conductive support is blocked. Good electrophotographic characteristics can be achieved by forming the semiconductive layer alone or in combination.

The charge generating layer is a charge generating material dispersed in a binder resin. In the case of an organic photoconductor, as a charge generating material, a phthalocyanine-based material such as a metal phthalocyanine or a metal-free phthalocyanine, an azo pigment having a skeleton such as carbazole, triphenylamine, fluorenone or oxadiazole, a perylene pigment, a quinone such as anthanthrone. Pigments, perylene pigments, benzoquinone and naphthoquinone pigments, polycyclic quinone pigments, quinone imine pigments and the like can be used alone or in combination of two or more. Also,
A low molecular weight transport material may be added if necessary.

Polyamide resin as the binder resin,
Polyester resin, polycarbonate resin, polyurethane resin, acrylic resin, polyacrylamide resin, phenol resin, etc. can be used.

As the hole-transporting substance, an oxazole derivative, an oxadiazole derivative, an imidazole derivative, a thiazole derivative, a triazole derivative, styrylanthracene, styrylpyrazoline or the like may be used alone or 2
Used as a mixture of two or more species.

The charge generating material and the binder resin are uniformly dispersed in a ball mill, a sand mill, a vibration mill or the like by using tetrahydrafuran, toluene, cyclohexanone, dichloroethane or the like as a dispersion liquid, and a spray coating method,
Using an immersion method or the like, the undercoat layer is coated to a thickness of 0.05 to 5 μm, preferably 0.2 to 1 μm. If the thickness is made thicker than necessary, the space charge increases, the movement of holes is impaired, and the effects of deterioration of light attenuation characteristics, increase of residual potential, and afterimage occur.

The first charge transport layer ("charge transport layer 1") is a charge transport material dispersed in a binder resin.
An oxazole derivative, an oxadiazole derivative, an imidazole derivative, a triphenylamine derivative, an α-phenylstilbene derivative, a toniphenylmethane derivative, an anthracene derivative, or the like can be used as the low-molecular-weight transport material. As the binder resin, polycarbonate resin (bisphenol A type, bisphenol C type, bisphenol Z type or copolymers thereof), polyarylate resin, polyester resin, polystyrene resin, vinyl acetate resin, etc. may be used alone or in combination of two or more. Can be used.

Further, in the present invention, an antioxidant may be added in order to improve the environmental resistance and suppress the decrease in sensitivity and the increase in residual potential. Examples of the antioxidant include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-.
Monophenol compounds such as butyl-4-ethylphenol, 2,2'-methylene-bis- (4-methyl-6)
-T-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-t-butylphenyl) and other bisphenyl compounds, 1,1,3-tris- (2-methyl-4-hydroxy) -5-t-Butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl)
Benzene, tetrakis- [methylene-3- (3 ', 5'-
Polymeric phenolic compounds such as di-t-butyl-4′-hydroxyphenyl) propionate] methane, and 2,5-di-t-octylhydroquinone, 2,
There are hydroquinones such as 6-didodecylhydroquinone, 2-dodecylhydroquinone, and 2- (2-octadecenyl) -5-methylhydroquinone.

The charge transport layer 1 needs to have a certain thickness or more in order to retain the charges of the photoconductor. The charging potential and the contrast potential are important for good image formation, and it is desirable that the contrast potential is at least 200 to 250 V, and preferably 400 V or more. The charging potential for obtaining the contrast potential is at least about 400V, preferably about 500 to 800V. The thinner the charge transport layer 1, the smaller the diffusion of light and charges in the layer, and thus the higher resolution is likely to be obtained. Further, since the trapping of carriers is relatively reduced, the rise of the residual potential is suppressed and the S / N becomes high. However, since the electrostatic capacity becomes large, the charging potential becomes low, and as a result, the contrast potential necessary for image formation becomes small. Further, as the coating film becomes thinner, the coating unevenness becomes more noticeable, and the potential unevenness is more likely to occur. Further, when there are minute defects, the electric field is concentrated, so that the withstand voltage margin is lowered and the risk of discharge breakdown increases. On the other hand, when the photosensitive layer is thick, the electrostatic capacity becomes small, so that the charging potential becomes high and the margin for discharge breakdown becomes large. However, since the degree of diffusion of light and electric charges is increased, adverse effects such as thickening of characters are likely to occur. Therefore, it is desirable to set the thickness of the charge transport layer 1 in the range of 10 to 40 μm, preferably 15 to 30 μm.

The resolution on the copy is the resistance of the transfer paper,
The resolution of the electrostatic latent image is as high as possible because it is affected by toner, carrier particle size, development method, original image dot system, transfer conditions, surface resistance of the charge transport layer 1, bulk resistance, etc. It is important to set it.

The second charge transport layer (charge transport layer 2) is formed in order to satisfy the electrophotographic characteristics and to improve the mechanical and electrical durability of the photoconductor. The electric resistance is set to a resistance on the order of 10 ¹³ Ω · cm, which is almost similar to that of the charge transport layer 1. When there is a large difference in the relative permittivities of the charge transport layer 1 and the charge transport layer 2, it is easy to form a trap level of holes near the boundary, and therefore it is not preferable that the relative permittivities differ. Numerically, it is desirable to set the value to be a value of about 2.5 to 4.0. Further, it is necessary to adopt a coating method in which the interface is not formed as much as possible so that holes moving from the charge transport layer 1 toward the surface are smoothly injected into the charge transport layer 2 to move.

The inorganic fine particles are oxides and are insulators, and when dispersed in a binder resin, traps are easily formed at the interface between the particles and the binder resin. Therefore, when the photoconductor is repeatedly used, residual potential is accumulated and the potential of the image area is increased, so that the image density and the resolution are likely to be reduced. Therefore, it is possible to dope an additive for improving the dispersibility, making the photosensitive layer uniform, inhibiting the formation of traps, and reducing the trap density.
Further, the photoconductor is charged by a charging member disposed close to the photoconductor, but corona products such as ozone and nitrogen oxides generated during charging adhere to the photoconductor surface layer or enter the photoconductor layer, It lowers the electric resistance and causes deterioration of image quality such as deterioration of resolution. In order to solve this, a small amount of antioxidant and plasticizer can be added. However, these additives are not always necessary, and there are cases where the charge transport layer is thin, the amount of the inorganic fine particles added is small, or there is no need to add them depending on the image system.

The charge transport layer 2 is formed by coating a coating liquid in which inorganic particles are dispersed in a binder resin in an appropriate amount to a target film thickness by using a coating method such as a spray method or a dipping method. The inorganic fine particles used in the charge transport layer 2 are 10 ¹⁴ to 10 ¹⁵ Ω.
It is desirable that it has a specific resistance of about cm, has water repellency, and continues its function. Generally used inorganic fine particles include titanium oxide, silica, alumina, zirconium oxide, indium oxide, silicon nitride, zinc oxide and the like. These oxides are structurally stable. The structure does not become unstable due to ozone or corona products such as nitrogen oxides generated at the time of charging, but depending on the material, the corona products may easily adhere, especially silica, indium oxide, etc. Is suitable for use as a high wear resistance material, but when exposed to ozone, nitrogen oxides, etc., it absorbs moisture in the atmosphere to lower the resistance, so when image formation is performed, it is normally around 60% RH. Image deletion may occur even in a humid environment. In this respect, alumina for improving the wear resistance of the photosensitive layer has a volume resistivity of 10 ¹⁴ to 10 ¹⁶ Ω · cm, is a fine powder having a particle diameter of 1 μm or less and having an appropriate hardness, and is not a little repellent. Since the material has a water action and the water repellent is effective, it is a suitable material for improving the abrasion resistance of the photoconductor, and good image formation can be performed. Titanium oxide is likewise a suitable material.

It is important to take measures to prevent image deletion due to sudden changes in the environment, and silane coupling agents, fluorine-based silane coupling agents and the like are generally used as water repellents. Depending on the manufacturing method, the charge transport layer 2 may be appropriately treated for water repellency without such treatment. However, it should be noted that the water repellent agent may cause image deletion on the contrary and may repeatedly increase the residual potential.

[0057] Inorganic fine particles of polycarbonate resin as a binder resin, polyethylene resin, polyurethane resin, acrylic resin, but can be distributed and used in the polyamide resin, preferably has no polar dependency, good transparency 10 ¹⁶ - A polycarbonate resin having a high resistance of about 10 ¹⁷ Ω · cm is suitable. When dispersing the inorganic fine particles in the binder resin, it is possible to improve the water repellency, lubricity, and improve the environmental characteristics and wear resistance characteristics by dispersing an appropriate amount of fluorine-based resin fine particles such as polytetrafluoroethylene. is there.

The amount of the inorganic fine particles dispersed is set in accordance with the durability required for the constituent materials such as the binder resin and the low molecular weight charge transporting material constituting the charge transporting layer 2. Depending on the added amount of the inorganic fine particles in the charge transport layer 2 and the dispersed particle size,
The film quality and electrophotographic characteristics are greatly affected. The addition amount is 10 to 4 by weight ratio with respect to the type of material constituting the charge transport layer 2.
0% is added, but a suitable amount is the process used,
When the lubricant is internally added to the charge transport layer 2 or externally added, it depends on the amount and method. For example, if a corona charging member with a low hazard is used, the durability of the photoconductor can be maintained even with a small addition amount, and if a contact charging member with a large hazard is used, the durability will be increased unless the addition amount is increased. Can't keep up. The abrasion of the photosensitive layer changes exponentially with the addition amount of the inorganic fine particles. When a contact charging member is used, if the addition amount is around 10% or less, it is likely to be rapidly worn. Also, if the addition amount is small, the friction coefficient becomes high, mechanical durability cannot be maintained, toner filming due to the developer, sticking of silica, etc. occur, and white spots, unevenness, etc. on the image occur. It tends to occur.

On the other hand, when the amount of addition is large, the amount of wear decreases, but when it is 40% or more, the amount of wear shows no dependence on the amount of addition. On the other hand, alumina in the coating liquid gradually precipitates, so that the storability of the coating liquid deteriorates, and the uniformity of the film is impaired, which also affects the coating. Furthermore, the surface roughness of the coating film is likely to deteriorate. When the amount of the inorganic fine particles added to the two layers of the charge transport layer is large, the light transmittance is lowered or diffused, the charge mobility is lowered, and the resolution is lowered, the residual potential is raised, and the sensitivity is lowered. When the amount of the inorganic fine particles added is large and the charge transport layer 2 is in a state in which it is difficult to wear, contaminants such as corona products adhering to the surface and filming due to toner components, which are obstacles to image formation, are not removed. In some cases, it may cause a decrease in resolution. Therefore, the preferable range of the addition amount of the inorganic fine particles is 10 to 40%, and the more preferable range is 10%.
~ 30%.

As the dispersed particle size in the charge transport layer 2 becomes smaller, deterioration of film quality, resolution and the like tend to be small and become dominant, but the effect on abrasion resistance is lowered. on the other hand,
The larger the dispersed particle size, the reverse of the above case,
The surface roughness becomes rough and the image quality deteriorates. Therefore, the average particle size after dispersion in the charge transport layer 2 is 0.3 to 0.
7 μm (measured by “CAPA500” manufactured by Horiba Ltd.) is desirable.

Although the thickness of the charge transport layer 2 depends on the required durability, it is usually set in the range of 2 to 10 μm, preferably about 3 to 8 μm. Of course, it is advantageous to make the thickness as thick as possible in order to improve durability. Since the charge transport layer 2 is a thin film in which fine inorganic particles are dispersed,
If there is unevenness or particle size dispersion, resolution, residual potential,
Since the mechanical durability is affected, it is desirable that the thickness of the charge transport layer 2 be at least 1 μm or less.

Next, the damping material used in the present invention will be described. The structure of the damping material 100 is shown in FIGS. 3 and 4. The damping material 100 is basically a support 1 having a spring function.
01, the vibration absorbing material 102, and the covering material 103. As shown in FIG. 4, the support having a spring function has a surface opposite to the vibration absorbing material (the center side of the photoconductor). The sheet-like member 104 may be stretched on the surface facing the sheet) to line it. The sheet-shaped member 104 is provided for the purpose of suppressing the vibration of the support body itself.
The sandwich of 04 and the vibration absorbing material 102 serves to suppress vibration and further suppress charging noise. Therefore, the sheet-like member 104 has an adhesive layer that completely adheres to the support 101 having a spring function and has a thickness of about 50 μm to 1 mm (fluorine resin sheet, PET sheet, etc.), rubber material (chloroprene rubber). , Silicone rubber, urethane rubber, butyl rubber, etc.)
A sheet having flexibility such as is preferably used.

In the present invention, the "support having a spring function" refers to a member which has a high resilience and serves as a support for the entire vibration damping material. For the support having a spring function, for example,
Besides polyethylene terephthalate (PET), stainless steel (SUS) plate, phosphor bronze plate, duralumin, etc., plastic or metal shape memory material can be used. In the present invention, a phosphor bronze plate and then a stainless plate are particularly suitable. The reason for using a support having a spring function is to bring the damping material into close contact with the inner wall of the photoconductor.
This is because it is easy to take out. As the thickness increases, the weight increases and the vibration damping effect increases, but since it becomes hard, insertion into and removal from the photoconductor becomes difficult.
Therefore, in the case of a phosphor bronze plate, 0.1 mm to 0.3 mm is preferable. For a photosensitive member having a diameter of about φ30 mm to 60 mm, a photosensitive member having a thickness of about 0.15 to 0.2 mm can be preferably used. When the thickness is 0.1 mm or less, the pressure contact force is weak, and
If it is 3 mm or more, it is hard, and there is a problem in work such as taking it out,
Although there is a concern that the support of the photoconductor will be distorted, a plate having a thickness that matches the photoconductor used may be used.
In the case of a stainless steel plate, the thickness is preferably about 0.1 to 0.4 mm, and since it resonates more easily than phosphor bronze, it may be lined with a sheet member.

The support having a spring function is formed into a tubular shape with a partial opening as shown in FIG. 5, and the vibration absorbing material and the covering material described below are attached thereto. The diameter of the cylinder is set according to the adhesion to the inner wall of the photoconductor when the photoconductor is mounted in the drum. For example, when a phosphor bronze plate of 0.1 mm is used and the inner diameter of the photoconductor is 29.5 mm, the phosphor bronze is cut into a plate width just like the cut edge when the vibration absorber and the covering material are applied. The plate is rolled as shown in FIG. 5 to form a tubular shape with a partial opening such that the outer diameter is about 32 to 35 mm. When inserting into the photoconductor while sliding it to the position shown in FIG. 6, and when taking out, the flange can be removed and the damping material can be pushed out, so that the photoconductor can be taken out relatively easily. When the diameter of the cylinder is large, the inner wall is strongly struck depending on the plate thickness. Therefore, depending on the thickness of the support, local distortion may occur and the roundness may be deteriorated.
A plate thickness of about 5 mm can be satisfactorily used. If the support having a spring function is excessively rounded, the outer diameter becomes small, so that the adhesion to the inner wall of the photoconductor becomes weak, and a gap is generated to reduce the effect of suppressing the charging noise. I can't get it. Further, since the damping material cannot be fixed sufficiently, it may move inside, and when the photoconductor rotates, slight vibration occurs, which may affect image quality.

If the thickness of the conductive support of the photoconductor is increased, the distortion of the support is reduced even if the repulsive pressure when the damping material is rolled is strong to some extent. It may be large, but if it is too large, it becomes difficult to take it out. Therefore, it may be adjusted by the inner diameter of the photosensitive member, the thickness of the photosensitive conductive support, the thickness of the support having a spring function, etc. It is better to set a size of about 20% increase.

In the present invention, the "vibration absorber" means a member that sharply attenuates the propagation of sound. A sheet having adhesiveness is preferable. Butyl rubber is the most suitable material for the vibration absorbing material used in the vibration damping material. It is a sheet that has almost zero air permeability, high water resistance, little secular change, good chemical stability, and strong adhesion. . Also, between butyl rubber,
For example, it is possible to further enhance the vibration damping effect by sandwiching different kinds of non-resonant members such as a fluororesin sheet having a low sound transmission coefficient. If the vibration absorbing material is thin, the effect will be reduced because it cannot fully absorb the vibration, and if it is thick, the effect will be high, but since the displacement and distortion are likely to occur, the vibration damping effect may be diminished. 1 depending on the outer diameter and thickness of the photoconductor
Use 2 to 4 mm thick butyl rubber, or
By using 1 to 2 sheets of butyl rubber having a thickness of 3 to 5 mm, almost expected results can be obtained.

In the present invention, the "coating material" means a member that covers the surface of the vibration damping material, so that the vibration damping material can be evenly adhered to the inner wall of the photoconductor, and the damping material can be easily formed. In order to be able to insert into and remove from the photoconductor, the vibration absorber with strong adhesiveness may stick to the inner wall of the photoconductor when it sticks out of the support, making removal difficult. It is used to prevent.

The condition of the covering material is that the material of the vibration absorbing material does not ooze out, the adhesion to the inner wall of the photosensitive member is excellent, the damping property is not impaired, and the material has a proper slip property. desirable. In addition, it can be inserted without damage when molded in the form of a vibration damping material, can be taken out in a normal shape, the charging sound can be transmitted to the vibration absorbing material without delay, and there is no obstacle to environmental damage and regeneration of the support. It is desirable to have it. For example, non-woven fabric of chemical fiber, fluororesin film, polyester film,
In addition to resin films such as polyethylene terephthalate film, there are Japanese paper and the like made from mulberry and sanpei. Further, it may be sandwiched with butyl rubber, and a film having good slipperiness that covers the adhesive may be stuck on the sandwich. Further, urethane rubber having a thickness of about 0.1 to 1 mm, a sponge (foam) sheet, a sheet having a low coefficient of restitution, or the like can be used. Since these sheets have insufficient slipperiness,
Lubricating members such as oils, zinc stearate, powdered fluororesin and the like can be applied and used. However, since the vibration absorbing material is a flexible material, a thin film that can make full use of the flexibility is desirable, and a thin material is preferable. That is, by utilizing the flexibility of the vibration absorber, the repulsive force spreading to the outside of the support gradually spreads the vibration absorber through the coating material to the inner wall of the photoconductor, increasing the adhesion to the inner wall of the photoconductor, and finally The anti-vibration material adheres to the inner wall of the photosensitive member over the entire surface. When a fluororesin film, a polyimide film or the like is used, a film having a thickness of 100 μm or less is suitable. In addition to the above, a non-woven fabric made of polyester-based or polypropylene-based resin having a thickness of about 200 to 300 μm, which is not loosened, is not easily torn, and has good slipperiness, can be suitably used as the coating material. These coating materials can be used with or without an adhesive layer.

Since butyl rubber having a strong adhesive property is preferably used as the vibration absorbing material, the end treatment of the coating material is important in order to prevent the end portions of the inner wall of the photoconductor and the vibration damping material from adhering to each other. For example, when a fluororesin film with an adhesive (for example, a product name “Teflon tape” manufactured by DuPont) is used, the end portion can be treated by rotating it to the back side of the support and adhering it to the support. In the case of not having an adhesive, for example, the covering material that has been turned to the back is a cellophane tape with an adhesive (for example, Nichiban Co., trade name "Cellotape") or a fluororesin film (for example, DuPont Co.,
Product name "Teflon tape"), polyimide film (for example, DuPont, product name "Kapton tape"), etc. can be used to cover the end of the covering material with the support, and the vibration absorber made of butyl rubber It can block adhesion to other parts. In addition to the above, the edge of the covering material is 5 to 10 m
Edge treatment can also be performed by forming an adhesive layer (gel adhesive, double-sided tape, etc.) with a width of m over the entire circumference.

The vibration damping material thus produced can realize the quietness to the extent that it does not bother the user when hearing the electrified sound. Also, since no adhesive is used on the inner wall of the photoreceptor,
Since the damping material can be easily taken out and attached, the photoconductor can be recycled as a material, and the damping material can be reused.

The charging method and charging member will be described below. The present invention can be used without any problem by the contact charging method, but preferably, the charging member is used by being arranged in the closest proximity to the photoconductor. More preferably, 30
It is used in a non-contact charging method by a roller charging member installed at a distance of ˜200 μm. A DC voltage on which an AC voltage (oscillation voltage) is superimposed is applied to the charging member. The reason for applying a DC voltage with an AC voltage (oscillation voltage) superimposed is 80 to 90
Even in a high humidity environment of% RH, or even if there is a variation in the gap between the charging member and the photosensitive member in the unit of μm in the length direction,
This is because the charging is performed relatively well.

The smaller the distance between the charging member and the photoconductor, the better the charging stability tends to be. However, the closer to the photoconductor the dust is on the charging member, toner paper dust, corona products, magnetic powder and other foreign matter. Are easily adhered, the surface resistance of the charging member becomes non-uniform, and the charging becomes non-uniform. In addition, when there is a hard foreign substance, it is pressed against the photoconductor and a hole is formed in the photoconductive layer, which easily causes discharge breakdown. Therefore, it is advisable to use them at a certain distance. When separated, the charging member is less likely to get dirty. However, if it is separated more than necessary, the discharge becomes non-uniform, which necessitates an increase in the applied voltage.However, this increases corona products, lowers the resistance of the photoconductor, and lowers the resolution. This tends to cause image non-uniformity. Therefore, it is desirable to keep the distance (gap) between the charging member and the photoconductor to the minimum necessary. A desirable void range is 30 μm to 200 μm, preferably 50 μm to 150 μm. 1000V to DC voltage of -700V to -850V for charging member
~ 2000V, 500Hz ~ 2.5KHz AC voltage is superimposed and applied, the surface potential is -400V ~ -800V
Charge to a certain degree.

Next, the cleaning device will be described. The cleaning device according to the present invention may reduce the durability of the photoconductor and the image quality by using hard magnetic particles such as a carrier, toner, corona products, paper dust, contaminants that cause problems in image formation such as filming, and the like. The purpose is to eliminate it so that it does not reach. The cleaning device 7 may be a cleaning blade 7a alone or a cleaning blade 7a and a cleaning brush 7b.

The cleaning blade 7a is, for example, JI.
Polyurethane rubber having an S-A hardness of about 60 to 80 degrees is used, and a rubber plate having a thickness of about 1.0 to 2.5 mm is applied to the photoreceptor with a counter method at a contact pressure of 40 to 90 mN / cm ^2. Contact. If the contact pressure is low, the cleaning efficiency is poor, and if it is high, the photoreceptor is damaged and the durability of the blade is shortened. Therefore, the contact pressure is preferably 60 to 80 mN / cm ² . The installation direction of the cleaning blade 7a may be either a reading system or a counter system, but the toner cleaning property is preferably the counter system (FIG. 1) in which the blade bites into the photoreceptor.

The material of the cleaning brush 7b is, for example, polyethylene, polypropylene, polyester, nylon or the like, and either an insulating material or a conductive brush can be used, but a conductive brush is preferable, and a conductive brush is used. The property is achieved by dispersing a conductive substance such as carbon or an ionic substance. The reason why the conductive brush is desirable is that when the brush is charged, magnetic powder or the like may adhere to the photoconductor again while remaining.
The resistance value may be a frictional charging value or a numerical value such that the potential charged from the photoconductor becomes 0 V almost at the same time as the charging.
The desired resistance value is about 10 ² to 10 ¹¹ Ω · cm. Usually, a brush having a resistance of about 10 ³ to 10 ⁸ Ω · cm is used, and is configured to be able to apply any voltage of ground, direct current, and alternating current. The brush can be either a straight-brush type or a loop type, but the abrasion resistance of the photosensitive layer is slightly different. In the case of a straight hair brush, the length of the spike is about 2 to 5 mm. The brush density is, for example, about 12 to 24 filaments of 150 to 800 denier / 12 to 48 filaments bundled into one unit, and 2000 to 30,000 filaments / in ^{2 of} flocked hair is used. The contact with the photoconductor is 1 to 1
It is about 4 mm, and the rotation of the brush is 80 to 240 rp.
The m and the rotation direction can be set to the photoconductor by either a counter or a reading method. The brush is equipped with a conductive flicker bar that knocks off the adhered toner, carrier, etc., which is grounded to the housing.

Next, the friction coefficient will be described. The friction coefficient is an important characteristic for improving the mechanical durability of the photosensitive layer. When a leveling agent (for example, silicone oil) is added, the friction coefficient of the photoreceptor without the coating layer becomes about 0.3 to 0.5 (value according to the Euler belt method described later), and when the leveling agent is not added Is 0.
It is about 5 to 0.6. 20 inorganic fine particles such as alumina
When about 40% is added, the friction coefficient is about 0.4 even when no leveling agent is added. However, even when a leveling agent is added to these photoconductors,
If 20 sheets are copied, the coefficient of friction immediately exceeds 0.6. It is considered that this is because the leveling agent is lost by the developer, copy paper, blade cleaning, and the adhesion of corona products. When the coefficient of friction decreases, the frictional resistance of the cleaning blade increases, so that the photosensitive layer is mechanically damaged, the abrasion is promoted, and silica or the carrier is easily pierced. This phenomenon is not an exception even when the inorganic fine particles are added, and if the friction coefficient of the surface layer of the photosensitive layer becomes higher, the amount is smaller than that when the inorganic fine particles are not added, but the abrasion surely proceeds.

Therefore, in order to maintain the photoconductor in a good condition for a long period of time, it is desirable to maintain the friction coefficient of the photoconductor at a low level. The preferable range of the friction coefficient is 0.2 to 0.5 when measured by the Euler belt method.
And more preferably 0.25 to 0.4. As the friction coefficient becomes lower, the contact pressure or contact pressure of the cleaning blade or the member such as the developer contacting the photosensitive member is relaxed, so that the abrasion of the photosensitive layer is reduced and is maintained at 0.2 or less. And wear hardly progresses. However, if the friction coefficient of 0.2 or less is maintained for a long time, the shaving action by the cleaning blade and the carrier (magnetic powder) disappears, so that the corona product and paper dust attached on the photosensitive layer, and further Contamination substances such as toner filming due to factors such as toner paper powder and corona products are not removed, and the surface of the photoconductor becomes low in resistance, resulting in deterioration of resolution and image quality such as image deletion. Therefore,
Although it is necessary to reduce the coefficient of friction, it is necessary to maintain the coefficient of friction required to sufficiently remove the foreign matter adhering to the photosensitive layer.

In the present invention, the friction coefficient is preferably calculated by the Euler belt method. The calculation method is as follows. A photosensitive member for measurement is fixed to a pedestal, and a fine paper of 85 μm thickness cut into a width of 30 mm and a length of 290 mm (manufactured by Ricoh Co., type 6200 paper, using vertical grain) is prepared as a belt.
Place the high-quality paper on the photoconductor,
A weight of 00g was attached, a digital force gauge for weight measurement was attached to the other end, the digital force gauge was pulled slowly, the weight at the start of belt movement was read, and the (static) friction was calculated using the following formula. Calculate the coefficient. μs = 2 / π × ln (F / W) where μs: coefficient of static friction, F: reading load, W:
The weight of the weight and the π: circular ratio Euler belt system are also described in known examples such as JP-A-9-68860.

Next, the external addition of the lubricant will be described. To improve the durability of the photoreceptor, by adding inorganic fine particles to the charge transport layer 2, when the corona charging method or the low-load contact charging method is used, the durability is increased by about 2 to 3 times that of the conventional one. I can. Even in this state, it is practically sufficient, but considering the maintenance-free, making the photosensitive member into a component, and the non-contact charging method having a strong hazard, it is desirable to further improve the durability. As means for increasing durability, there are a method of internally adding a lubricant (fluorine resin, silicone oil, etc.) to the photosensitive layer, and a method of externally adding a lubricant to the surface layer of the photosensitive layer. In the present invention, the external addition method is preferred. The external addition method supplies a lubricant to the surface layer of the photoconductor to lower the friction coefficient of the surface, soften the friction resistance with a member such as a cleaning blade or a developer that comes into contact with the photoconductor, and reduce the abrasion of the photoconductive layer. It is a method for achieving this, and is superior to the internal addition method in terms of effect sustainability, level stability, reduction, and controllability. On the other hand, by supplying the lubricant, it is possible to weaken the influence of the deterioration of the appearance of the photoreceptor, such as toner filming and sticking of developer additive components such as silica to the photoreceptor, and the corona that easily adheres to the surface layer of the photoreceptor. Product,
The adhesive force of foreign matter such as paper powder and toner is weakened, and the effect of easily maintaining the surface property of the photoreceptor is produced. As a result, when used for a long period of time, the internal addition method has a friction coefficient of 0.4 to 0.6, while the external addition method has a friction coefficient of 0.2 to 0.4 (all are based on the Euler belt method). Further, the abrasion of the photosensitive layer is significantly suppressed, and the life can be dramatically extended to 5 to 20 times that of the conventional one.

A specific method of supplying the lubricant to the photoconductor is to directly or indirectly supply the powdery or block-form lubricant to the photoconductor. For example, 1/100 in developer
Powdery zinc stearate or PTFE of ~ 1 / 10μm
(Polytetrafluoroethylene resin) is added to the toner in a proportion of 0.01 to 0.5%. When the amount of lubricant added is excessive, the friction coefficient of the photoconductor decreases, so the wear of the photoconductor dramatically decreases, but the physical properties of the toner (for example, Q / M) can be controlled by adding too much lubricant. There is a possibility that the toner cannot be controlled because the toner cannot be controlled, the toner is excessively supplied, the toner is scattered, or the friction coefficient is too low. Usually, it is desirable to add 0.01 to 0.3% to the toner,
In the case of zinc stearate, about 0.02-0.3%, P
In the case of TFE, about 0.01 to 0.1% is preferable. P
When TFE is added, the effect of reducing the friction coefficient is higher than that of zinc stearate, so it is better to add TFE in a smaller amount than that of zinc stearate. The amount of the lubricant added is sufficient to suppress filming and poor appearance due to the toner, and should not be added more than necessary.

A method of externally adding a block-shaped or film-shaped lubricant to the surface layer of the photoreceptor is to bring a member to be abraded, for example, a dedicated brush or a cleaning brush (fur brush) into contact with the lubricant, Scrape and attach to photoreceptor. By controlling the contact pressure between the brush and the lubricant and the biting amount of the brush, the amount supplied to the photoconductor is controlled. There is also a method in which a film-like lubricant having a thickness of about 50 to 200 μm is brought into contact with the photoconductor and supplied. This method is a method of externally adding a lubricant to the photoconductor by lightly contacting the photoconductor with a film lined with an elastic member, and by controlling the pressing of the lubricant,
Control the coefficient of friction.

Although any of these can be used in the present invention, it is preferable to add a proper amount of fine particles of the lubricant to the toner by a method that does not require a mounting space and supply control operation.

[0083]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

[0084]

[Example 1] <Method for producing photoconductor> A photoconductor was produced in the following manner. φ30mm, length 340mm, wall thickness 0.9
mm aluminum drum with undercoat layer (U
L) coating liquid, charge generation layer (CGL) coating liquid, charge transport layer (CTL) coating liquid, and dip coating in order,
By heating and drying each at 120 ° C. for 20 minutes, an undercoat layer of 3.5 μm, a charge generation layer of 0.15 to 0.2 μm, 22 to 25
A photoconductor having a charge transport layer 1 of μm was prepared. Further, a binder resin, a low-molecular-weight charge transport substance (donor), inorganic fine particles (metal oxide), a dispersion aid and a solvent were placed in a glass pot on the photoconductor and dispersed in a ball mill for 24 hours to obtain an average particle size (Horiba (Manufactured by Mfg. Co., Ltd., measured with “CAPA500”) A coating solution of about 0.45-0.55 μm is prepared, and reciprocally applied twice using a spray method, and heated and dried at 150 ° C. for 20 minutes to contain 25% of inorganic fine particles. The electrophotographic photosensitive member on which the charge transport layer 2 having a thickness of 5 to 6 μm is formed is completed. All “parts” described below represent parts by weight.

[0085] [Coating liquid for undercoat layer]   Alkyd resin (manufactured by Dainippon Ink and Chemicals, Inc., trade name "Beckosol 1307 -60-EL ") 6 parts   Melamine resin (manufactured by Dainippon Ink and Chemicals, Inc., trade name "Super Beckamine G -821-60 ") 4 parts   40 parts of titanium oxide ("CR-EL" manufactured by Ishihara Sangyo Co., Ltd.)   200 parts of methyl ethyl ketone

[Coating Liquid for Charge Generation Layer] 10 parts of bisazo pigment having the structure of [Chemical formula 1] below

[Chemical 1] Polyvinyl butyral 2 parts 2-butanone 200 parts Cyclohexanone 400 parts

[Coating Liquid for Charge Transport Layer 1] Bisphenol Z type polycarbonate (manufactured by Teijin Chemicals,
Trade name "Z Polycar") 10 parts Low molecular charge transport material having the structure of [Chemical formula 2] 8 parts Tetrahydrafuran 200 parts

[Chemical 2]

[0088] [Coating liquid for charge transport layer 2] Bisphenol Z type polycarbonate resin (Mv50,000) 10 parts 7 parts of the charge transport material having the structure of [Chemical Formula 3] below Inorganic fine particles: Alumina (Sumitomo Chemical Co., Ltd., "AA-03") 5.7 parts Dispersion aid (by BYK Japan, "BYK-P104") 0.08 part Tetrahydra 700 parts Cyclohexanone 200 parts

[Chemical 3]

<Charging member> An 8 mm brass rod rod was coated with epichlorohydrin rubber in which carbon was uniformly dispersed, and molded to have a thickness of 14 mmφ, an electric resistance of 2 to 6 × 1.
PET (polyethylene terephthalate) cut into a rhombus having a thickness of 49 μm, a width of 10 mm and a length of 43 mm is attached to both ends of a charging member of 0 ⁵ Ω · cm (100 VDC is applied) to form a spacer with a gap of about 50 μm between the photoconductors. A non-contact charging member was created.

<Damping material> 0.1 mm cut into 72 mm x 280 mm as a support of the damping material having a spring function.
A phosphor bronze plate having a thickness of 5 mm is uniformly rounded so that the outer diameter is 32 to 33 mmφ, and a butyl rubber sheet (made by Sugawara Kogyo Co., Ltd.) having a thickness of 1 mm is used as a vibration absorbing material on each end of the support 1 m
3 pieces were laminated over the entire inner surface with m remaining, and further 80 μm thick fluororesin tape (made by Nitto Denko, as a covering material,
"903UL heat-resistant Teflon tape") was rolled over the entire surface to the back side of the support so that the vibration-proof material did not project, and a vibration-damping material having a tubular shape with a partial opening was completed. After the damping material was packed inside the aluminum drum of the above-prepared photoreceptor, flanges were attached to both ends to adjust the form of the photoreceptor, and a photoreceptor containing the damping material was prepared.

<Confirmation of Effect of Damping Material> The method of confirming the effect of the damping material was carried out in a laboratory under the conditions of temperature and humidity of 24 to 25 ° C. and 65% RH. A photoconductor incorporating a damping material was installed in a laboratory on a pedestal supported at both ends, and the photoconductor was set with a charging roller processed so as to maintain a gap of 50 μm. The voltage applied to the charging roller is a DC voltage of -800V with a sine wave of 1.4KV / 1.35KHz superimposed, and a sound level meter is placed on a pedestal of 50mm, and the tip of the probe is 30cm away from the photoconductor. The sound pressure difference was confirmed by switching between ON and OFF. The sound pressure in the laboratory was about 46 dB. The larger the number in the table, the higher the sound pressure, which means that the sound becomes unpleasant to the ear. The smaller the number, the better. Normally, it can be said that a sound pressure of 4 dB or less is unnoticeable, and a sound pressure of 2.5 dB or less is considerably high in quietness.

<Evaluation of Image Quality etc.> As an image forming apparatus for evaluation, Imagio 250 having an LD element with an image exposure wavelength of 655 nm was prepared. Ricoh black toner with a particle size of about 7 μm (fluidizer S
iO ₂ = 0.7%, TiO ₂ = 0.8%, zinc stearate lubricant (SZ2000) = 0.2% added),
A 5% -concentration developer (Ricoh prototype developer) dispersed in a magnetic carrier (FPC-300LC) having a particle size of 60 μm was used. As a device for applying an AC voltage superimposed DC voltage to the charging member, a Yokogawa function generator (FG-300) and a Nagano Aichi Electric high voltage power supply (HV-2) are used.
55) is prepared, and the frequency of FG300 is 1.2 KHz,
The output is set to 14.5V, the output is input to the HV-255 having a voltage amplification capacity of 100 times, the DC voltage of the high-voltage power supply is set to -740V, and the image forming apparatus for image evaluation Imagio 250 is operated. The surface potential of the photoconductor prepared by the above-described manufacturing method was adjusted to −600V. The evaluations were made on the friction coefficient before and after running through the paper, the amount of abrasion of the photosensitive layer, the image quality under normal humidity environment (22 ° C / 65% RH) and high humidity environment (30 ° C / 90% RH), and various characteristics of the appearance of the photoreceptor. evaluated.

The abrasion amount of the photosensitive layer was determined by using an eddy current type film thickness meter (Fisherscope mms) manufactured by Fisher Co., and measuring the film thickness at 13 points before and after running, and judging the average value thereof. Image quality judgment is based on the specified standard test chart with a JIS standard bamboo shoot chart as the original and the resolution, sharpness, etc. are judged, and a 5% line chart is used for the original for running paper. The target of 100,000 sheets was evaluated at the rate of 99 sheets continuously for one cycle.
In order to take out the installed damping material, a 5 mm thick aluminum disk, which is about 0.8 mm smaller than the inner diameter of the photoconductor, is attached with a 5 mm thick felt as a cushioning material. A jig with a shaft attached was created and the damping material was pushed out slowly. The evaluation results are shown in Table 1.

[0094]

Example 2 A support having a spring function as a damping material was cut from a phosphor bronze plate to a size of 72 mm × 280 mm, which was 0.15.
An electrophotographic photosensitive member having a built-in vibration damping material was prepared under the same conditions as in Example 1 except that a stainless steel (SUS304) plate having a thickness of mm was used. The effect of the damping material, the image quality, etc. were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0095]

[Example 3] An electrophotographic photoreceptor containing a vibration damping material under the same conditions as in Example 1 except that the support having a spring function of the vibration damping material was changed from a phosphor bronze plate to a duralumin plate having a thickness of 0.1 mm. It was created. This photoreceptor was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0096]

[Embodiment 4] An electrophotographic photoconductor having a built-in vibration damper under the same conditions as in Embodiment 1 except that the support having a spring function of the vibration damping material is changed from a phosphor bronze plate to a copper plate having a thickness of 0.2 mm. Created. This photoreceptor was evaluated in the same manner as in Example 1.
The evaluation results are shown in Table 1.

[0097]

[Table 1]

When a phosphor bronze plate or a stainless plate is used as the support having a spring function, the sound pressure of the charging noise is slightly higher on the stainless plate, but both the phosphor bronze plate and the stainless plate have a good vibration damping effect. If the difference between the ON time and the OFF time is about 4 dB or less, the sound pressure of 2.5 to 3 dB is judged to be a good value because it is not perceptible to the hearing. When mounted on the evaluation machine, the vibration noise was not a audible noise that was slightly audible and mixed with other driving noises. The vibration-damping material installed in the photoconductor was stored in the environment of 40 ° C and 10 ° C for 5 days and then taken out. Even if the photoconductor was violently shaken left and right, there was no feeling that it moved inside, the center of gravity did not move and the support It was suggested that the pressure of was sufficiently functioning and that the damping material was in close contact with the inner wall.

The friction coefficient after running 100,000 sheets of A4 horizontal copy paper after mounting on the evaluation machine was 0.4.
The following was maintained, and the result of the photoreceptor including the charge transport layer 2 having a thickness of 5 μm was such that the durability of 200,000 sheets or more could be guaranteed. Moreover, there was no image deterioration in a high humidity environment, and good resolution was exhibited. 22/65% and 30/90 in Table 1
% Is 22 ° C / 65% RH (normal temperature and normal humidity environment), 30 ° C /
90% RH (high temperature, high humidity environment) is shown. The same applies to the following examples and comparative examples. Also, the damping material was pushed out smoothly without any problem.

On the other hand, when a duralumin plate or a copper plate is used as the support having a spring function, the sound pressure is 50 to 5
2 dB, the sound pressure was slightly higher than that of the phosphor bronze plate or the stainless plate, and a continuous sound called keen was generated. When the photoconductor was shaken to the left and right, the center of gravity of the photoconductor was shifted to the back side, which caused poor adhesion of the damping material to the inner wall of the photoconductor and created a gap between the coating material and the inner wall of the photoconductor. It is thought to be a tame. Also, while duralumin is a material that easily resonates, copper is a heavy and relatively good support, so it is considered that there was a difference in sound pressure between the two, but the duralumin plate has a small spring effect (repulsion force is small). It is possible that the pressure was not sufficient. Regarding the image quality, a slight distortion was caused on the photoconductor, and a slight reduction in resolution was observed.

[0101]

Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that no vibration damping material was incorporated. This photoreceptor was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[0102]

[Table 2]

When the damping material was not attached, the image quality was good, but the charging noise was extremely high (sound pressure was approximately 52%).
~ 53 dB) occurred.

[0104]

Example 5 A vibration damping material using chloroprene rubber as a vibration absorbing material was prepared as follows. Stick a strong double-sided tape made by Nichiban Co., Ltd. on one side of 3 mm thick chloroprene rubber,
It was evenly attached to the outside of a phosphor bronze plate having a plate thickness of 0.15 mm, which was rounded to an outer diameter of 32 mm and cut into 72 mm × 280 mm. On the chloroprene rubber, a fluororesin tape (Scotch brand, "Teflon tape No. 5490") was adhered over the entire surface of the vibration absorber so that no gap was formed. The prepared vibration damping material was incorporated into a photoreceptor prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0105]

Example 6 A vibration damping material was prepared in the same manner as in Comparative Example 1 except that the chloroprene rubber was changed to urethane rubber having a thickness of 3 mm. The prepared vibration damping material was incorporated into a photoreceptor prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0106]

[Table 3]

Both the chloroprene rubber and the urethane rubber were sufficiently pressed against the inner wall of the photoconductor, the damping material was well fixed, and the friction coefficient and the image quality were both good. However, the sound pressure of the charging sound was high, and each showed a sound pressure of 50 dB or more.

[0108]

[Comparative Example 2] The vibration absorbing material, which is obtained from Inoac Corporation and is sufficiently soft as compared with rubber, is 2 m.
m thick urethane foam (micropolymer sheet, density 0.2 g / cm ³ , tensile strength 3.1 kg / cm ² ,
25% compression load 0.2 kg / cm ² , product name “Polon L
A damping material using E20 ") was prepared as follows. After sticking a strong double-sided tape made by Nichiban Co., Ltd. to a phosphor bronze plate with a thickness of 0.15 mm cut to an outer diameter of 32 mm and cut to 72 mm x 280 mm, peel off the release paper, and then slowly apply urethane foam with a weak force. I pressed and glued. No coating material was provided on this urethane foam. The vibration-damping material thus prepared was incorporated into a photoreceptor prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0109]

[Table 4]

When urethane foam is used as the vibration absorbing material without providing the covering material, the damping material is sufficiently pressed against the inner wall of the photoconductor, the damping material is in a good fixed state, and the friction coefficient,
The image quality was good. However, the sound pressure of the charging sound was high, and the sound pressure difference was 5 dB. Also, the friction resistance is large, and it is not easy to take it out even if a jig for pushing out the damping material is used, and the shape of the phosphor bronze plate that is the support is crushed, making it impossible to reuse the damping material. became.

[0111]

Example 7: 0.15 cut into 72 mm x 280 mm
0.13 mm on mm-thick stainless steel (SUS304) plate
Fluororesin tape with thick adhesive (Nitto Denko "903
UL heat resistant Teflon tape ", hereinafter referred to as" lining material 1 ") was applied to create a damping material. The lining material 1 is attached to the inside of the cylindrical shape of the damping material. This backing material 1 was laminated to a stainless steel plate in advance and then slowly processed into a cylindrical shape. The outer diameter of the cylinder was 32 mm. Three 1mm thick butyl rubbers are used as vibration absorbers attached to the outside of the stainless steel plate, and 90mm thick fluororesin tape (3M, product name "Teflon tape") does not protrude from the butyl rubber. Then, the end was turned to the inside of the damping material so that the butyl rubber did not stick out. The prepared damping material was inserted into the photosensitive member prepared in the same manner as in Example 1 at approximately the center thereof, and the damping material was sufficiently mixed at the inner wall of the photosensitive member at 35 ° C. and 50% RH.
Stored in the environment for 3 days. After storage, it was taken out and the vibration damping effect against the charging noise was evaluated in the same manner as in Example 1.
The results are shown in Table 5.

[0112]

Example 8 A vibration damping material was prepared in the same manner as in Example 7 except that the stainless steel plate was changed to a phosphor bronze plate having a thickness of 0.15 mm cut into 72 mm × 280 mm. The prepared damping material was inserted into the photoconductor in the same manner as in Example 7, and the damping effect against charging noise was evaluated. The results are shown in Table 5.

[0113]

[Embodiment 9] The backing material 1 of Embodiment 8 is made of urethane foam having a thickness of 2 mm (the same as that of Comparative Example 2, hereinafter referred to as "lining material 2").
And the backing material 2 was attached to a phosphor bronze plate with a strong adhesive double-sided tape to prepare a damping material having a cylindrical outer diameter of about 31 mm. The prepared damping material was inserted into the photoconductor in the same manner as in Example 7, and the damping effect against charging noise was evaluated. The results are shown in Table 5.

[0114]

[Example 10] A damping material was prepared in the same manner as in Example 8 except that the backing material 1 was changed to a polyester film with an adhesive (hereinafter referred to as "backing material 3"). The prepared damping material was inserted into the photoconductor in the same manner as in Example 7, and the damping effect against charging noise was evaluated. The results are shown in Table 5.

[0115]

[Table 5]

By backing the support, the sound pressure is reduced to 0.
An improvement of about 5 dB was achieved, and quietness was improved.
The image quality is good without any problems,
With respect to the abrasion of the photosensitive layer, the adverse effect of inserting the damping material did not occur. The vibration damping material was taken out by removing the flanges attached to both ends of the photoconductor and using the jig described in Example 1. In all cases, the butyl rubber did not adhere to the inner wall of the photoconductor and was damaged. It was possible to take out without.

[0117]

[Embodiment 11] A polypropylene-based spunbonded nonwoven fabric 1 having a thickness of 280 µm (trade name "Syntex PSO-Mitsui Oil Co., Ltd."
4230 ") was used to make a damping material as follows.
280 mm x 70 rounded to an outer diameter of about 33 mm
A 0.15 mm thick phosphor bronze plate cut into mm was stretched with 3 mm thick butyl rubber and further laminated with 1 mm butyl rubber. On top of that, one piece of the above covering material was carefully attached so as not to cause wrinkles, and the end portion of the covering material was attached to the support with cellophane tape to prevent the butyl rubber from protruding.
The damping material thus prepared was inserted into the center of the photosensitive member prepared in the same manner as in Example 1, the position was marked and the flange was attached, and the sound pressure was measured according to the measuring method described in Example 1. . After that, 100,000 sheets were passed and the image quality, friction coefficient, and film thickness of the photosensitive layer were measured. After this 30 ℃
After confirming the image quality in a high humidity environment of / 90% RH, the flange was removed, and the fixing state of the damping material and the ease of removal were confirmed. The results are shown in Table 6.

[0118]

Twelfth Embodiment A coating material is applied from a nonwoven fabric 1 to a polypropylene-based spunbonded nonwoven fabric 2 having a thickness of 280 μm (manufactured by Mitsui Oil Co., Ltd.,
A vibration damping material was prepared in the same manner as in Example 11 except that the product name was changed to "Syntex PS-106"). The prepared damping material was inserted into the photoconductor as in Example 11, and the image quality and the like were confirmed. The results are shown in Table 6.

[0119]

Example 13 The same procedure as in Example 11 was performed except that the coating material was changed from the nonwoven fabric 1 to a 100% polyester spunbonded nonwoven fabric 3 having a thickness of 170 μm (trade name “Syntex MY-R200” manufactured by Mitsui Oil Co., Ltd.). I made a choreography. The prepared damping material was inserted into the photoconductor as in Example 11, and the image quality and the like were confirmed. The results are shown in Table 6.

[0120]

Example 14 A coating material is applied from the nonwoven fabric 1 to a polyethylene terephthalate film (PET film) having a thickness of 50 μm.
A vibration damping material was prepared in the same manner as in Example 11 except that the vibration damping material was changed to. The prepared damping material was inserted into the photoconductor as in Example 11, and the image quality and the like were confirmed. The results are shown in Table 6.

[0121]

[Table 6]

Although the sound pressure of the PET film was slightly higher, it was not so much as noise, and all the coating materials had a good charging noise suppressing effect. On the other hand, the image quality, the coefficient of friction, and the amount of abrasion of the photosensitive layer were good, and the electrophotographic characteristics were sufficient. The damping material was in a good fixed state, there was no displacement from the preset mark, and there was no movement even if it was shaken violently to the left and right. The damping material could be taken out without any problem, and there was almost no deformation of the damping material.

[0123]

Example 15 On the charge transport layer 1 of the photoconductor prepared by the same method as in Example 1, a charge transport layer 2 was further formed by a spray method to a thickness of 5 μm by the following production method. The amount of alumina added to the charge transport layer 2 is 5%.

[Coating Liquid for Charge Transport Layer 2] Bisphenol Z-type polycarbonate resin (Mv50,000) 10 parts Charge transport material having a structure of [Chemical Formula 2] 7 parts Dispersion aid (manufactured by BYK Chemie Japan, “BYK-P104 )) 0.08 parts Tetrahydrafuran 700 parts Cyclohexanone 200 parts Alumina ("AA-03" manufactured by Sumitomo Chemical Co., Ltd.) 0.9 parts [Chemical Formula 2]

The damping material is a phosphor bronze plate having a thickness of 0.15 mm cut into 280 mm × 72 mm, which is rounded to have an outer diameter of φ33 mm, and three 1 mm thick butyl rubbers manufactured by Sugawara Kogyo Co., Ltd. Further, a fluororesin tape ("Teflon tape" manufactured by 3M Co., Ltd.) was adhered so as not to create a gap, and a treatment was performed so that the butyl rubber did not protrude. The damping material thus created was inserted into the center of the photoconductor while squeezing. The photoreceptor thus prepared was evaluated in the same manner as in Example 1.
The toner used was the one to which 0.2% zinc stearate was added as a lubricant, as in Example 1. The results are shown in Table 7.

[0126]

Example 16 A photoreceptor was prepared in the same manner as in Example 15 except that the coating liquid for charge transport layer 2 described in Example 15 was changed to 1.9 parts. A φ30 mm photoconductor was prepared in which the amount of addition was 10%. The photosensitive member thus prepared was evaluated in the same manner as in Example 15. The results are shown in Table 7.

[0127]

Example 17 A photoreceptor was prepared in the same manner as in Example 15 except that the coating liquid for charge transport layer 2 described in Example 15 was changed to 5.7 parts of alumina. A φ30 mm photoconductor was prepared with the addition amount of 25%. The photosensitive member thus prepared was evaluated in the same manner as in Example 15. The results are shown in Table 7.

[0128]

Example 18 A photoreceptor was prepared in the same manner as in Example 15 except that the coating solution for charge transport layer 2 described in Example 15 was changed to 7.3 parts of alumina. A φ30 mm photoconductor was prepared with the addition amount of 30%. The photosensitive member thus prepared was evaluated in the same manner as in Example 15. The results are shown in Table 7.

[0129]

[Example 19] Example 15 except that the coating liquid for charge transport layer 2 described in Example 15 was changed to 11.4 parts of alumina.
A photoconductor was prepared in the same manner as in, and a photoconductor having a diameter of 30 mm was prepared in which the amount of alumina added to the charge transport layer 2 was 40%. The photosensitive member thus prepared was evaluated in the same manner as in Example 15. The results are shown in Table 7.

[0130]

[Example 20] A photoreceptor was prepared in the same manner as in Example 15 except that the coating solution for charge transport layer 2 described in Example 15 was changed to 14 parts of alumina. A photoconductor having a diameter of 45 mm and a diameter of 30 mm was prepared. The photosensitive member thus prepared was evaluated in the same manner as in Example 15. The results are shown in Table 7.

[0131]

[Example 21] A photoreceptor was prepared in the same manner as in Example 15 except that the coating solution for charge transport layer 2 described in Example 15 was changed to 17 parts of alumina. A φ30 mm photoreceptor having 50% was prepared. The photosensitive member thus prepared was evaluated in the same manner as in Example 15. The results are shown in Table 7.

[0132]

[Example 22] A photoconductor was prepared in the same manner as in Example 15 except that 4.3 parts of titanium oxide (CR-97) was used instead of alumina in the coating liquid for the charge transport layer 2 described in Example 15. A φ30 mm photoconductor was prepared in which 20% of titanium oxide was added to the charge transport layer 2. The photoconductor thus prepared is used in Example 15.
Evaluation was carried out by the same method as described in. The results are shown in Table 7.

[0133]

Example 23 A photoconductor was prepared in the same manner as in Example 15 except that the coating solution for charge transport layer 2 described in Example 15 was changed to 9.2 parts of titanium oxide (CR-97). A φ30 mm photoconductor was prepared in which 35% of titanium oxide was added to the charge transport layer 2. The photoconductor thus prepared is used in Example 15.
Evaluation was carried out by the same method as described in. The results are shown in Table 7.

[0134]

[Table 7]

There were no problems with the fixed state of the damping material, and there was no problem with the quietness of the charging noise, and there was no harshness in the ears. Also, there was no problem in taking out the damping material. As the inorganic fine particles are added, the wear resistance is gradually improved, but the degree of improvement tends to be less than around 25%. When 40% is added, the image quality is deteriorated and the coating film becomes uneven. In the case of titanium oxide, the resolution was slightly lowered at 35%, but it was within the practical range. After the run under these conditions, when the added amount of alumina was 10%, the abrasion resistance was a little insufficient and the abrasion was 4.2 μm. Further, when the content of alumina was 5%, the photosensitive layer was abraded so much that the charge transport layer 2 was completely worn away, and foreign matter was found to be adhered to the outer appearance of the photosensitive member, resulting in an image with many irregularities. On the other hand, alumina is 45
% Or 50%, the abrasion of the photosensitive layer was further reduced, but the film formation was likely to be non-uniform, and the image part of the repetitive potential was increased by 15 to 200 V, and the density was thin and uneven. There were many images.

[0136]

Example 24 Spacers were attached to both ends of the charging member so that the distance between the photosensitive member and the charging member was 30 μm, and the effect of the gap between the charging member and the photosensitive member on the characteristics was evaluated. A rhombus-shaped spacer film having a width of 10 mm and a length of 43 mm was attached to a charging member having a diameter of 14 mm. A 25 μm polyimide film with an adhesive (trade name “Kapton tape”, manufactured by DuPont Toray) was used as the spacer film, and the film was bonded to the charging member. The damping material used in Example 15 was mounted on the photoreceptor prepared in the same manner as in Example 1, and the characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 8.

[0137]

Example 25 The polyimide film with adhesive of 25 μm of Example 24 was changed to a polyester film of 50 μm so that the distance between the photoreceptor and the charging member was 50 μm, and the film was adhered to the charging member with a double-sided tape. The damping material used in Example 15 was mounted on the photoreceptor prepared in the same manner as in Example 1, and the characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 8.

[0138]

Twenty-sixth Embodiment The distance between the photosensitive member and the charging member is 100 μm.
So that the 25 μm polyimide film with adhesive in Example 24 was changed to a 90 μm fluororesin tape (“Teflon tape”), the double-sided tape was adhered to the charging member. Example 15 was applied to the photoreceptor prepared in the same manner as in Example 1.
The damping material used in 1. was attached, and the characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 8.

[0139]

Example 27: Distance between photoconductor and charging member is 200 μm
In such a manner, the polyimide film with adhesive of 25 μm of Example 24 was changed to a polyethylene terephthalate resin film (PET) of 180 μm and adhered to the charging member with a double-sided tape. The vibration damping material used in Example 15 was attached to the photoreceptor prepared in the same manner as in Example 1, and
The characteristics were evaluated by the same method. The results are shown in Table 8.

[0140]

[Table 8]

When the gap between the charging member and the photosensitive member was set to 30 μm, a slight whitish stain could be seen, but the image quality was hardly affected, and the quietness of the charging sound was good. It was Further, when the thickness was 50 μm or 100 μm, the contamination of the charging member was further reduced. Void 2
When it was set to 00 μm, there was almost no contamination of the charging member, but there was a tendency that the sound pressure slightly increased and the image uniformity and resolution tended to decrease, but both were within the practical range. It was Although it is possible to enhance the vibration damping effect by increasing the thickness of the vibration absorbing material, the number of vibration absorbing materials to be configured is limited in the photosensitive member of 30 mmφ. By increasing the gap, charging unevenness increases, but it is necessary to increase the application conditions in order to eliminate this charging unevenness. However, this increases ozone and nitrogen oxides, resulting in deterioration of image quality. Considering these matters, the upper limit of the void is about 200 μm.

[0142]

[Comparative Example 3] An evaluation was carried out in the case where the spacer was not set on the charging member. To the photoreceptor described in Example 1,
The damping material used in Example 15 was attached, and the characteristics were evaluated in the same manner as in Example 1. However, the AC voltage condition applied to the photoconductor was kept as it was, and the DC voltage was reset so that the surface potential became -600V. The results are shown in Table 9.

[0143]

COMPARATIVE EXAMPLE 4 A polyethylene terephthalate resin film was used as the charging member, and an evaluation was made in the case where a gap of about 250 μm was formed between the film and the photoconductor. The damping material used in Example 15 was mounted on the photoreceptor described in Example 1, and the characteristics were evaluated in the same manner as in Example 1. However,
The AC voltage condition applied to the photoconductor was left unchanged, and the DC voltage was reset so that the surface potential became -600V.
The results are shown in Table 9.

[0144]

[Table 9]

When the gap was 0 μm (contact with the photoconductor), the sound pressure was good, but the entire charging member became white, the charging waveform became jagged, and the potential dropped by about 20 to 30 V. Further, in the case of 250 μm, the contamination of the charging member was almost zero, but the image unevenness increased, the photosensitive layer was worn out as a whole, and there was a tendency for uneven wear on the back side. This is probably because the amount of corona products generated increased.

[0146]

In the invention according to claim 1 of the present invention, as a method for improving annoying charging sound generated when an AC superimposed DC voltage is applied to a charging member arranged so as to face a photoconductor, The method of fixing the damping material in close contact with the inner wall of the photoconductor in the body is effective, but this damping material is applied to the support having a spring function, the vibration absorbing material, and the coating material in order from the center side of the photoconductor. By including the three layers configured, the support having a spring function and the covering material make the damping material evenly adhere to the inner wall of the photoconductor to be fixed, and the vibration absorbing material and the covering material efficiently absorb the charging sound and resonate. Is suppressed to such an extent that it does not cause discomfort, and the covering material has a function of preventing the vibration absorbing material having strong adhesiveness from adhering to other parts. Therefore, the damping material used in the present invention has a great effect of suppressing the charging noise, and since the photoconductor whose life has reached the end can be easily separated from the damping material, it is possible to recycle the photoconductor and reuse the damping material. It is easy and is preferable as energy saving and resource saving.

According to the second aspect of the present invention, by selecting a phosphor bronze plate or a stainless plate as the support having a spring function, the spring action of phosphor bronze or stainless steel controls the inner wall of the photosensitive member with an appropriate pressure. It becomes possible to fix the vibrating material, and it becomes relatively easy to take it out from the photoconductor.

In the invention according to claim 3, a sheet-like member is attached to the surface of the phosphor bronze plate or the stainless plate opposite to the surface on which the vibration absorbing material is stretched, so that the sheet is sandwiched and supported by the vibration absorbing material. The vibration emitted from the body can be further suppressed, and the quietness of the charging sound can be increased.

Further, in the invention according to claim 4, by using butyl rubber as the vibration absorbing material, the vibration at the time of charging can be rapidly attenuated and the charging noise can be efficiently suppressed. Further, by utilizing the strong adhesive function of butyl rubber, the adhesiveness with the support can be made strong and the vibration of the support can be suppressed.

According to the fifth aspect of the present invention, the vibration absorbing member is made of a thin non-woven fabric or a resin film as the covering material on the upper surface of the vibration absorbing member, so that the vibration of the photoconductor is transmitted to the vibration absorbing member without delay and attenuated. be able to. Further, by using a thin non-woven fabric or a film-shaped covering material, the adhesion to the inner wall of the photoconductor can be improved, and it can be easily carried out at the time of mounting in or taking out from the photoconductor.

Further, in the invention according to the sixth aspect, by applying a DC voltage in which an AC voltage is superposed to the charging member of the image forming apparatus to form an image, stable followability is provided even if the environment deteriorates. Moreover, even if the gap between the charging member and the photoconductor is not uniform, uniform image quality can be achieved. Further, by using the photoconductor on which the second charge transport layer in which the inorganic fine particles are dispersed is formed, abrasion resistance of the photoconductor can be improved and stable electrophotographic characteristics can be maintained in a good state.

In the invention according to claim 7, the distance between the photosensitive member and the charging member mounted on the image forming apparatus is 30 μm or more, and 2 or more.
By providing the voids of 00 μm or less, it is possible to reduce the contamination of the charging member, thereby suppressing deterioration of image quality and deterioration of the charging member (uneven electric resistance, uneven wear, etc.). In addition, since the charging member does not contact the photoconductor, there is no difference in linear velocity between the charging member and the photoconductor, and there is no wear of the photoconductor due to foreign matter adhering to the charging member. It is possible to prevent the life of the photosensitive member from being shortened, and further improve the durability of the photosensitive member.

Further, in the invention according to claim 8, there is provided a charge-transporting layer comprising the specific vibration-damping material according to any one of claims 1 to 5, which further comprises inorganic fine particles dispersed on the charge-transporting layer. Using the laminated photoreceptors, a charging member, an image exposure system, a developing device, a transfer device, a separating device, and a cleaning device are arranged in order, and a DC voltage with an AC voltage superimposed is applied to the charging member. With the image forming apparatus configured as described above, it is possible to provide a reproducible photoconductor as well as to prolong the life of the photoconductor, while providing stable image quality for a long period of time.

According to the present invention, the charging sound generated when charging the photoconductor can be suppressed to a level that does not impair hearing.
Further, the method for suppressing charging noise using the electrophotographic photoreceptor of the present invention is not a method of fixing the vibration damping material with an adhesive, but a vibration damping material can be obtained by using a plate material having a spring function for the support. It is pressed against the inner wall of the photoconductor and fixed. Also, this facilitates insertion and allows easy removal. By adopting this method, the photoconductor and the damping material can be easily separated, the photoconductor that has reached the end of its life can be recycled, and the damping material can be reused, which is environmentally preferable. It is a method.

Further, by using a photoconductor having a second charge transport layer in which inorganic fine particles are further dispersed on the charge transport layer, higher durability, longer life and resource saving can be achieved. Things are possible.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a copying process in which the present invention is used.

FIG. 2 is an explanatory diagram of a photosensitive member configuration used in the present invention.

FIG. 3 is a cross-sectional view of a damping material including a support having a spring function, a vibration absorbing material, and a coating material according to the present invention.

FIG. 4 is a cross-sectional view of a damping material having a structure in which a sheet-shaped member is attached to the inside of a support having a spring function and having a spring function.

FIG. 5 is an explanatory diagram showing a shape of a vibration damping material completed by stacking a vibration absorbing material and a covering material on a support which is rolled into a cylindrical shape.

FIG. 6 is a conceptual diagram showing a position and a state in which a damping material is inserted and fixed in the photoconductor.

[Explanation of symbols]

1 photoconductor 1a conductive support 1b Subbing layer 1c Charge generation layer 1d Charge transport layer 1 1e Charge transport layer 2 2 charging member 3 image exposure system 4 Developing device 5 Transfer device 6 Separation device 7 Cleaning device 7a cleaning blade 7b cleaning brush 8 fixing device 9 copy paper 100 damping material 101 Support having spring function 102 Vibration absorber 103 coating material 104 sheet-like member

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinji Naba             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H035 CA07 CB02 CB04 CG03 CZ00                 2H068 AA39 AA54 AA60 FC01                 2H071 CA02 CA05 DA15 EA14                 2H200 FA10 GA11 GA23 HA14 HB12                       HB43 HB45 HB46 JA02 LA14                       MA03 MA14 MA20 MB06 NA06

Claims (8)

[Claims] 1. A charging member is charged with a surface potential required for image formation by applying a DC voltage superposed with an AC voltage to the charging member.
In an electrophotographic photoreceptor having a built-in vibration damping material, the vibration damping material includes at least three layers of a support having a spring function, a vibration absorbing material, and a covering material, and the vibration damping material is arranged in order from the side facing the center of the electrophotographic photoreceptor. An electrophotographic photosensitive member comprising a support having a spring function, a vibration absorbing material, and a coating material in that order. 2. The electrophotographic photoreceptor according to claim 1, wherein the support having a spring function is a phosphor bronze plate or a stainless plate. 3. The electrophotographic photosensitive member according to claim 2, wherein a sheet-shaped member is adhered over the entire surface of the phosphor bronze plate or the stainless plate opposite to the surface where the vibration absorber is adhered. . 4. The electrophotographic photoconductor according to claim 1, wherein the vibration absorbing material is butyl rubber. 5. The electrophotographic photoreceptor according to claim 1, wherein the coating material is a non-woven fabric or a resin film. 6. A first charge transporting layer and a second charge transporting layer in which inorganic particles are dispersed are formed by applying a direct current voltage superposed with an alternating current voltage to a charging member arranged in close proximity to each other. An image forming apparatus characterized by performing image formation using an electrophotographic method of forming a latent image by image exposure after charging the electrophotographic photoreceptor according to any one of 1 to 5 above. . 7. An electrophotographic photoreceptor having a thickness of 30 μm to 200 μm.
The image forming apparatus according to claim 6, wherein the image forming apparatus is charged by a non-contact charging member separated by μm. 8. The electrophotographic photoreceptor according to claim 1, wherein a first charge transport layer and a second charge transport layer in which inorganic fine particles are dispersed are formed. A charging member, an image exposure system, a developing device, a transfer device, a separating device, and a cleaning device are arranged in this order, and a DC voltage with an AC voltage superimposed is applied to the charging device member to charge the electrophotographic photoreceptor. An image forming apparatus that forms an image by doing so.