JP2012008364A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device using an electrophotograhic photoreceptor substantially excellent in cleaning nature.SOLUTION: The image forming device comprises: a photoreceptor having a surface layer on which independent projections are formed with a material different form the surface layer; and lubricant supplying means for supplying the lubricant to the photoreceptor. The shapes of the projections formed on the photoreceptor has a maximum length of 10-500 μm and a height of 0.5-5 μm, and the number of projections are 2-5000 pieces per one meter square on the surface of the photoreceptor.

Description

  The present invention relates to an image forming apparatus used for a copying machine, a laser printer, a facsimile, and the like.

  In recent years, an organic photosensitive layer containing an organic photoconductive material on a support as an electrophotographic photosensitive member (hereinafter also simply referred to as “photosensitive member” or “image carrier”) mounted on a laser printer or a digital copying machine. A photoconductor provided with is generally used. Among them, a multilayer organic photoreceptor in which a charge generation material and a charge transport material are contained in separate layers is mainly used. This is due to cost, productivity, and freedom of material design.

  Since these electrophotographic photoreceptors are exposed to mechanical external force, electrical or chemical hazards in the electrophotographic image forming process, they undergo various deteriorations. In particular, recently, the output of color images has increased, and electrophotographic organic photoreceptors that are used repeatedly over a long period of time are required to have durability against such deterioration more than before.

  With regard to mechanical durability, a toner mainly composed of a coloring material and a resin is used with a developer containing hard inorganic fine particles as an additive, and a paper containing an additive composed of hard fibers or clay during transfer is used. Wearing progresses because it is strongly pressed and rubbed, or because it is slid strongly by the cleaning blade during cleaning. For this reason, polycarbonate, polyarylate or the like having high durability is used as the binder resin for the organic photoreceptor. (See Patent Documents 1 and 2).

  Conventionally, various improvements in the mechanical durability have been proposed in which a protective layer is provided on the surface of the photoreceptor. Also in this protective layer, a protective layer in which hard metal oxide fine particles are dispersed, or a layer obtained by crosslinking and hardening the protective layer itself has been studied (see Patent Document 3). In addition, studies have been made to improve the lubricity of the surface of the photoconductor to prevent the film from being scraped, and its practical application has been advanced (see Patent Documents 4 and 5).

  Although these photoconductors have a certain degree of wear durability, they are still unsatisfactory, and in long-term repeated image formation, small scratches and cracks may occur on the surface of the photoconductor, Also, since the surface of the photoreceptor is slid by the tip of a hard blade for cleaning, the blade may be chipped and fine toner may slip through. In particular, when the latter occurs, black streaks appear in the image and the image quality deteriorates at a stroke. Image degradation due to toner slipping has become an urgent issue for highly durable photoreceptors.

  The largest cause of abrasion on the surface of the photoreceptor is the cleaning blade. However, if the transferability of the toner can be improved, residual toner is reduced, pressure applied to the cleaning blade can be reduced, and chipping of the blade can be advantageously suppressed. In Patent Document 6, irregularities having a specific shape such as a prism shape, a wave shape, a cone shape, a pyramid shape, or a well shape are formed on the surface of the photosensitive member by a touch roll or a stamper, thereby improving the toner releasability. Consideration has been made. Further, there is a description that filler particles containing silicon and fluorine are contained in all layers of the charge transport layer to reduce the toner transfer rate and the stress applied to the photoreceptor. However, the photoconductor having the concavo-convex shape in this study, when repeatedly forming an image, the edge of the cleaning blade may be chipped off when the frictional resistance of the photoconductor surface increases. Therefore, there was toner slipping.

  Recently, Patent Document 7 has proposed a method of manufacturing a photoreceptor in which a fine uneven portion shape is transferred to the surface of the photoreceptor. A concave shape having reproducibility is formed on the surface layer by performing molding while maintaining the glass transition point temperature of the charge transport layer, the temperature of the mold, and the temperature of the support in a specific relationship. Further, Patent Document 8 describes a method of roughening the surface of the photoreceptor by irradiating the surface layer of the photoreceptor with laser light and forming a plurality of recesses in the surface layer. As a result of examining these, it is said that a resistance adjusting material may be contained in the protective layer, but a residue due to laser light remains in the hole and is not easily discharged, which is not preferable because it interferes with image formation.

  In Patent Document 9, it is considered that a plurality of specific concave-shaped portions are formed on the surface of the photoreceptor to improve the cleaning property. This concave-shaped opening portion has a specific major axis diameter, minor axis diameter and depth. In addition, this concave-shaped part is present in the surface layer with a specific surface density, thereby preventing scratches on the surface that grows due to external forces acting in the image forming process such as a cleaning blade. is doing. However, there may be a case where a small black spot appears when image formation is repeated due to clogging of the developer additive in the recess. The formation of the recesses on the surface of the photoreceptor by the conventional laser or mold does not make a difference in forming fine holes in the surface layer at high density, and makes the surface layer itself mechanically brittle.

In Patent Document 10, a fine concavo-convex shape having a plurality of concave portions and convex portions formed continuously is formed on the surface of the photosensitive member, and the depth of the concave portion, the height of the convex portion, and the longest axis of the convex portion. The variation in length and the length of the shortest axis are specified. However, this is for the purpose of reducing the discharge caused by the electric memory and is different from the present invention. Further, in the definition of the concavo-convex shape, there is a lack of presentation of a specific size, resulting in a shortage in actual use. It has been found that the problem or object of the present invention is not a solution.
As described above, in the conventional technology, it has been difficult to achieve both prevention of scraping and chatter of the cleaning blade and suppression of toner slipping and filming.

  In recent years, with the increase in output of color images, higher image quality has been demanded more than ever. As a color toner, the technology has shifted from a conventional pulverized toner to a polymerized toner, and the toner has been made spherical for the purpose of high image quality. As for the toner particle size, it is obvious that toner in an area of 6 μm or smaller, which is finer than the conventional particle shape, is used, and in the future, the technology will further advance toward a smaller particle size. In such a trend, from the viewpoint of high image quality and high reliability, the cleaning performance of residual toner remaining on the photoreceptor every time an image is formed has become more demanding than ever. There is a need for a photoconductor and an image forming apparatus with dramatically improved performance.

  An object of the present invention is to provide an image forming apparatus that uses an electrophotographic photosensitive member that is remarkably excellent in cleaning performance, and to further improve the reliability of the image forming apparatus.

The inventors of the present invention have intensively studied the cleaning properties of polymerized toner, spherical toner, and small particle size toner, which are becoming mainstream in a configuration in which a lubricant is applied to the photosensitive member. In order to apply the lubricant on the photoconductor, the lubricant application brush scrapes the lubricant while vibrating due to the contact of the convex portion of the photoconductor, and applies the lubricant on the photoconductor. In addition to the side effects of cleaning, such as blade turning and chattering, it is possible to prevent the toner from slipping out due to excessive application of lubricant and malfunctions (charger contamination, etc.) due to that, and the lubricant is uniform. Because it has a structure applied to the surface, it can suppress wear of non-convex parts due to charging fatigue and rubbing fatigue, and can solve background stains on the image due to wear of non-convex parts. Long period good image forming apparatus capable of maintaining high image quality has reached the present invention found that obtained by use.
The present invention is solved by the following (1) to (11).

(1) An image forming apparatus comprising: a photosensitive member having an independent convex portion formed of a material different from the surface layer on the surface layer; and a lubricant supply unit that supplies a lubricant to the photosensitive member. As for the shape of the convex portions formed on the photoconductor, the longest diameter of the convex portions is 10 to 500 μm, the height of the convex portions is 0.5 to 5 μm, and the number of convex portions is the surface layer of the photoconductor. An image forming apparatus having ^{2 to} 5000 per unit surface area (mm ² ).
(2) The image forming apparatus according to (1), wherein the lubricant is a metal soap.
(3) The image forming apparatus according to (1) or (2), wherein the lubricant supplying means applies a lubricant downstream of at least one cleaning element.
(4) The image forming apparatus is an image forming apparatus having an intermediate transfer body, wherein the intermediate transfer body also has a lubricant supply means, and the coverage of the lubricant satisfies the following relationship ( The image forming apparatus according to any one of 1) to (3).
Lubricant coverage on intermediate transfer member <Lubricant coverage on photoconductor (5) The binder resin of the surface layer is a thermoplastic resin, and the binder resin of the convex portion contains a curable resin. The image forming apparatus according to any one of (1) to (4).
(6) The image forming apparatus according to any one of (1) to (5), wherein the convex portion includes an inorganic pigment.
(7) The image forming apparatus according to any one of (1) to (5), wherein the convex portion includes resin particles.
(8) The image forming apparatus according to any one of (1) to (7), wherein the convex portion contains a charge transport material.

According to the present invention, the convex portions provided on the surface of the photosensitive member can solve the side effects at the initial stage of cleaning such as blade turning and chattering, and cleaning properties of polymerized toner, spherical toner, and small particle size toner, which are becoming mainstream nowadays. Since the image forming apparatus having excellent transferability is obtained and the lubricant is applied to the photoconductor, it is possible to suppress wear of the non-convex portion due to charging fatigue or friction fatigue, and image due to wear of the non-convex portion. An excellent image forming apparatus capable of solving the above background stain and maintaining high image quality over a long period of time can be obtained.
In addition, the lubricant application brush removes the lubricant while vibrating due to the vibration caused by the contact of the convex part of the photoreceptor, and applies the lubricant to the photoreceptor. Can be achieved.

It is a figure which shows an example of the shape of the convex part of the photoreceptor surface in this invention. It is a figure explaining the method to calculate the diameter and height of the convex part on the surface of a photoreceptor. It is a figure explaining the method to calculate the diameter and height of the convex part on the surface of a photoreceptor. It is a figure which shows the outline | summary of a spray coating apparatus. It is a figure which shows the outline of the continuous type inkjet apparatus used in order to form a convex part on the photoreceptor surface. It is a figure which shows the thermal-type inkjet apparatus used in order to form a convex part on the photoreceptor surface. FIG. 2 is a diagram illustrating a piezo-type inkjet device used for forming a convex portion on the surface of a photoreceptor. It is a figure which shows an example of a lubricant coating device. It is sectional drawing which shows an example of a layer structure of a photoreceptor typically. It is sectional drawing which shows the other example of a layer structure of a photoreceptor typically. It is the schematic for demonstrating an image forming apparatus. 1 is a schematic diagram for explaining a tandem full-color electrophotographic apparatus. FIG.

[Composition of convex part]
The surface of the photoreceptor according to the present invention has a configuration having a large number of convex portions and concave portions surrounding the convex portions.
The shape of the protrusion on the surface of the photoreceptor can be measured using a known laser microscope, optical microscope, or electron microscope. For example, an ultra-deep shape measuring microscope VK-8550 manufactured by Keyence Corporation as a laser microscope, a surface shape measuring system Surface Explorer SX-520DR model manufactured by Ryoka System Co., Ltd., a scanning confocal laser microscope OLS3000 manufactured by Olympus Corporation, Lasertec Corporation The 3CCD real color confocal microscope OPTELICS H1200 made by the company can be used. As an optical microscope, a digital microscope VHX-500 manufactured by Keyence Corporation and a 3D digital microscope VC-7700 manufactured by OMRON Corporation can be used. As the electron microscope, a 3D real surface view microscope VE-9800 manufactured by Keyence Corporation can be used. Using these microscopes, it is possible to observe and measure the shape of the convex portion, the state of the skirt, the arrangement, the height, or the top.

(Basic configuration)
An example of the irregular shape on the surface of the photoreceptor in the present invention is shown in FIG. The black portion in FIG. 1 is a concave portion surrounding the convex portion, and the white portion is a concave portion surrounding the convex portion. When the convex portions are aligned, the concave portion has a mesh shape.
In the photoconductor of the present invention, by providing convex portions on the surface of the photoconductor with the height and number thereof controlled, the toner cleaning property of the photoconductor is improved, and accumulation of foreign matters such as wax on the surface of the photoconductor occurs. The toner has excellent toner cleaning properties and image stability. The reason for this is that, due to the large number of convex portions on the surface of the photoreceptor, the pressing force of the blade and the pulling force in the rotation direction are evenly distributed compared to the smooth surface of the photoreceptor. It is thought to be for improvement. Furthermore, since the mesh-shaped recessed part surrounding a convex part is connected, it has the path | route through which a foreign material is discharged | emitted, and since it prevents accumulation of a foreign material, it has the outstanding image stability.

(Diameter and height of convex part)
The diameter and height of the convex portion are obtained as follows.
Arbitrary 10 1 mm ² areas on the photoconductor are determined, and then the diameter and height of any two convex portions (or two if there are only two) in each area are obtained. Thus, a total of 20 convex diameter and height data are obtained and averaged to obtain the convex diameter and height.
The diameter and height of the convex portion are calculated from the profile of the surface on which the convex portion is formed. The calculation method is shown in FIG.
First, let the diameter of the convex part be the lateral distance | x ₁ −x ₂ | of the surfaces of x1 and x2, which are the lowest points of both ends of the convex part, on the profile passing through the apex of the arbitrary convex part. The measurement was performed at five points in any direction with respect to one convex portion, and the maximum value was taken as the diameter of the convex portion.
Next, with respect to the height of the convex portion, on the profile passing through the vertex of the arbitrary convex portion, a line connecting the lowest points of the hems at both ends thereof is used as a reference line, and a vertical line from the vertex of the convex portion to the surface of the photosensitive member is formed. The distance between the intersection of the vertical line and the reference line and the apex of the convex portion was taken as the height of the convex portion.
FIG. 2-2 is a diagram illustrating an example of a preferable convex portion formation state.

  The convex diameter suitable for the electrophotographic photosensitive member of the present invention is desirably 10 μm or more and 500 μm or less. When the convex diameter is larger than 500 μm, dispersion of the cleaning blade pressing force becomes insufficient (non-uniform), and it becomes difficult to ensure the cleaning property and reliability of the spherical toner and the small particle toner targeted by the present application. The same applies to the dispersion of the transfer pressing force. When the number of points at which the transfer pressure is dispersed decreases, abnormal images such as insect worms tend to occur. If the diameter of the convex portion is 10 μm or less, the concentration of the cleaning blade pressing force becomes large, which is not preferable from the viewpoint of blade life.

  The height of the convex portion suitable for the electrophotographic photosensitive member of the present invention is desirably 0.5 μm or more and 5.0 μm or less. When the thickness is 0.5 μm or less, the blade in the recess sufficiently follows, the dispersion of the pressing force cannot be obtained, and the high cleaning function which is the aim of the present invention cannot be obtained. If it exceeds 5 μm, the blade and the transfer body are strongly damaged, and the reliability is impaired.

(Number of convex parts)
A laser microscope was used to measure the number of protrusions. In the measurement, a drum sample was first placed on a work table, and the tilt was adjusted to adjust the level, and the three-dimensional shape data of the surface of the electrophotographic photosensitive member was captured. At that time, the objective lens used a magnification of 10 times, and the number of convex portions visible in the field of view of the analysis screen was counted per area of 1000 μm square as the number of convex portions.
The number of suitable convex portions of the electrophotographic photosensitive member of the present invention is preferably 2 to 5000 per unit surface area (mm ² ).
When the number is less than 1, the cleaning blade pull-in is increased due to an increase in the contact area between the cleaning blade and the photosensitive member, and the toner cleaning performance is deteriorated.

Also, in the present invention, substances that interfere with image formation, such as discharge products, need to be efficiently removed and cleaned from the photoreceptor, so that the protrusions formed on the surface layer are independent of each other. The formed portion other than the convex portion is a surface layer portion, and the surface layer portions are continuously connected so that it is difficult to accumulate discharge products.
Thus, since each convex part needs to exist independently, there exists an allowable number depending on the longest diameter of the convex part.
When the longest diameter of the convex part is 10 μm, 5000 pieces / mm ² ,
When the longest diameter of the convex part is 100 μm, 50 pieces / mm ² ,
When the longest diameter of the convex portion is 500 μm, the upper limit is 2 pieces / mm ² .

(Formation method of convex part)
In the method for forming a convex portion according to the present invention, a mesh is disposed on a photoconductor on which a surface layer is formed, and the photoconductor and the mesh are rotated. There is a method to form protrusions on the photoreceptor by spray coating, in which case the protrusions of diameter, height, etc., depending on the mesh opening, the distance between the mesh and the photoreceptor, the composition of the protrusion forming liquid, etc. The shape can be adjusted.
As another method, there is a method of forming a convex shape on the surface of the photosensitive member by printing a convex forming material on the rotated photosensitive member by using a screen printing method. In this case, the shape of the convex portion can be determined by the opening of the screen and the solid content of the convex forming liquid.

As yet another method, there is a convex forming method using an ink jet method. A plurality of nozzles for forming droplets are incorporated in an ink jet print head, and a line head system that matches the width of the photoconductor or a serial head system in which the head moves while rotating the photoconductor may be used. There is no limitation on the ejection method, either an on-demand system or a continuous system, and either thermal or piezo elements can be used. In the ink jet method, it is possible to drop a picoliter unit droplet for forming a convex of about 10 μm, and high-speed dropping or on-demand dropping is possible. There is a feature such that the dropping point) can be prevented from overlapping.
The ink jet method is most suitable as a method for forming the convex portion according to the present invention.
Hereinafter, the spray coating method and the ink jet method will be described in more detail with respect to the method for forming the convex portions.

As one specific example of the method for forming the convex portion of the present invention, a spray coating method for forming the convex portion by spraying on the surface of the electrophotographic photosensitive member will be described.
The spray method will be described below.

In order to obtain the convex portion of the present invention, a mask corresponding to a desired pattern is installed on the drum side. Examples of the mask used include known metal meshes and resin meshes.
A known method can be used as the spray coating method. FIG. 3 shows an outline of the spray coating apparatus.
A photosensitive drum around which a mask is wound is rotated at a predetermined speed by a rotation driving device (not shown). Next, while supplying the coating liquid and gas to the moving application body having a spray gun at a predetermined pressure, the coating liquid and the gas are oscillated (moved) in the axial direction of the photosensitive drum, and the sprayed coating liquid is sprayed on the photosensitive drum. A coating film can be formed.

The coating conditions can be formed under the following conditions. Using a coating solution comprising components different from the outermost layer of the photoreceptor, the viscosity of the coating solution is 0.5 to 10 mPa · sec, the solvent ratio is high boiling point solvent / low boiling point solvent = 1/3 to 3/1, concentration 0 5 to 10 wt%, the rotational speed of the photoreceptor is 60 to 1000 r. p. m, an oscillating speed of 2 to 100 mm / sec, an air pressure of 0.05 to 5 MPa, and an air flow rate of 1 to 100 L / min.
As described above, the surface of the photosensitive member is covered with a mesh, and a convex portion different from the outermost layer of the photosensitive member can be formed on the photosensitive member by spray coating from the mesh.
Since the longest diameter of a convex part has the suitable range of 10-500 micrometers, 30 mesh-635 mesh can be utilized as a mesh which can be used.

Next, a method for forming a convex shape on the surface of the photoreceptor by ink jet will be described.
The ink jet method is a method in which the convex portion forming liquid is atomized and sprayed directly onto the surface layer of the photoreceptor to form the convex portion.
FIG. 4 is a schematic view of a continuous ink jet apparatus.
The ink (coating liquid) pushed out from the nozzle to the continuous machine by the pump becomes fine droplets by the ultrasonic oscillator. The droplet is charged by the electrode, and the activation is bent by the deflection electrode as necessary, and reaches the printing surface (photoconductor surface). The coating liquid that has not been bent by the deflection electrode is sucked into a collection port called gutter and returns to the ink tank again.
In the formation of the protrusions, the diameter, height, and number of areas of the photosensitive member-like protrusions can be adjusted by the coating liquid solid content, pump flow rate, droplet interval, nozzle diameter, head feed speed, and the like.

5 and 6 show an on-demand type ink jet apparatus that ejects a necessary amount of liquid droplets when necessary.
FIG. 5 shows a thermal method, and FIG. 6 shows a piezo method.
The thermal method is a principle in which a heater is attached to a part of a fine tube filled with ink, and the heater is instantaneously heated, thereby generating bubbles in the ink and ejecting the ink.
The piezo method is a method in which a piezo element is attached to a part of a fine tube filled with ink, and a voltage is applied to the piezo element to deform the element to eject droplets.

In the formation of the convex portions, the diameter, the height, and the number per area of the convex portions on the photosensitive member can be adjusted by the coating liquid solid content, deformation amount, fine tube diameter, signal interval, head feed interval, and the like.
In order to make the material composition of the convex part different from that of the outermost layer of the photoreceptor, it is necessary to prepare the convex part forming liquid so that the active ingredient other than the solvent differs at least one kind between the outermost layer and the convex part. is there.
In particular, when a curable resin or an inorganic pigment that is not included in the outermost layer is used as the material of the convex portion, the wear resistance is excellent and the sustainability of the effect of the present invention is increased.

When a charge transporting material different from the outermost layer is used as the material of the convex portion, a charge transporting agent having strong gas resistance can be used when the charge transporting agent of the outermost layer has low resistance to the discharge gas.
When resin particles that are not included in the outermost layer are used as the material of the convex portion, it is possible to ensure the lubricity and releasability of the convex portion, and the cleaning property and transferability are further improved.

Hereinafter, the material configuration constituting the convex portion will be described in more detail.
[Crosslinked resin]
A cross-linked resin may be used as a material constituting the surface convex portion. After coating the paint, a resin having a crosslinked structure is formed by a polymerization reaction or a polycondensation reaction. Since the resin film has a cross-linked structure, the wear resistance is strong. Further, when a crosslinkable charge transport material is blended, the charge transport property is similar to that of the charge transport layer.
As the charge transport material to be contained in the surface convex portion, a known charge transport compound can be used. Examples of the polymerizable or crosslinkable monomer or oligomer include a chain polymerization compound having an acryloyloxy group and a styrene group, and a sequential polymerization compound having a hydroxyl group, an alkoxysilyl group, and an isocyanate group. A combination of a hole transporting compound and a chain polymerization material is preferable from the viewpoint of the obtained electrophotographic characteristics, versatility, material design, and production stability. Particularly preferred is a system in which a compound having a crosslinking is crosslinked. It can be crosslinked and cured using heat, light and radiation. The crosslinkable resin is preferably three-dimensionally crosslinked.

"Binder composition of crosslinked resin"
The trifunctional or higher functional binder component may contain caprolactone-modified dipentaerythritol hexaacrylate or dipentaerythritol hexaacrylate. This often improves the wear resistance of the crosslinked film itself or increases the toughness.

The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure is preferably trimethylolpropane triacrylate, caprolactone-modified dipentaerythritol hexaacrylate, or dipentaerythritol hexaacrylate.
These can be obtained from reagent manufacturers such as Tokyo Kasei Co., Ltd., Nippon Kayaku KAYARD DPCA series, DPHA series and the like.
In addition, an initiator such as Ciba Specialty Chemicals Irgacure 184 may be added to the solids in an amount of about 5 to 10 wt% in order to promote or stabilize the curing.

  Examples of the crosslinkable charge transport material include a chain polymerization compound having an acryloyloxy group and a styrene group, and a sequential polymerization compound having a hydroxyl group, an alkoxysilyl group, and an isocyanate group. A compound having one or more acryloyloxy groups can be used. Alternatively, the composition may be combined with a monomer or oligomer having one or more (meth) acryloyloxy groups not including a charge transport structure. Such a compound can be contained in at least the coating liquid, and can be crosslinked and cured by applying energy such as heat, light, or radiation such as electron beam or γ-ray.

  The dispersion solvent used in preparing the crosslinked resin coating is preferably a solvent that sufficiently dissolves the monomer. In addition to the ethers, aromatics, halogens, and esters described above, cellosolves such as ethoxyethanol, 1- Mention may be made of propylene glycols such as methoxy-2-propanol. Of these, methyl ethyl ketone, tetrahydrofuran, cyclohexanone, and 1-methoxy-2-propanol are preferable because they have a lower environmental impact than chlorobenzene, dichloromethane, toluene, and xylene. These solvents can be used alone or in combination.

  If necessary, low molecular compounds and leveling agents such as antioxidants, plasticizers, lubricants, ultraviolet absorbers, and polymer compounds described in the charge transport layer are added to the crosslinked resin film in the same manner as the charge generation layer described later. You can also. These compounds can be used alone or as a mixture of two or more. When a low molecular weight compound and a leveling agent are used in combination, sensitivity deterioration often occurs. For this reason, the amount used is generally 0.1 to 20 wt%, preferably 0.1 to 10 wt%, and the leveling agent used is about 0.1 to 5 wt% in the total solid content of the paint.

  In the present invention, the filler may contain filler fine particles from the viewpoint of wear resistance. As the filler fine particles, the following can be used. Examples of the organic filler material include fluorine resin powder such as polytetrafluoroethylene, silicone resin powder, and carbon fine particles.

The carbon fine particles are particles having a structure mainly composed of carbon. Particles having a structure such as amorphous, diamond, graphite, amorphous carbon, fullerene, zeppelin, carbon nanotube, carbon nanohorn, and the like. Among these structures, particles containing hydrogen-containing diamond-like carbon or amorphous carbon structure have good mechanical and chemical durability. The diamond-like carbon or amorphous carbon film containing hydrogen is a particle in which similar structures such as a diamond structure having an SP3 orbit, a graphite structure having an SP2 orbit, and an amorphous carbon structure are mixed.
Diamond-like carbon or amorphous carbon fine particles are not limited to carbon, but may contain other elements such as hydrogen, oxygen, nitrogen, fluorine, boron, phosphorus, chlorine, bromine and iodine. Absent.

Examples of inorganic filler materials include metal powders such as copper, tin, aluminum, and indium, metal oxides such as silicon oxide, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, and bismuth oxide, and potassium titanate. An inorganic material is mentioned. In particular, from the viewpoint of the hardness of the filler fine particles, it is advantageous to use an inorganic material among them. In particular, metal oxides are good, and silicon oxide, aluminum oxide, and titanium oxide can be used effectively. Also, fine particles such as colloidal silica and colloidal alumina can be used effectively.
The average primary particle size of the filler fine particles is preferably from 0.1 to 1.0 μm from the viewpoint of light transmittance and wear resistance.

  The higher the filler material concentration, the better the wear resistance and the better. However, when the filler material concentration is too high, the residual potential increases and the writing light transmittance of the surface layer decreases, which may cause side effects. Therefore, it is about 50% by weight or less, preferably about 30% by weight or less based on the total solid content.

Furthermore, these filler fine particles can be surface treated with at least one kind of surface treatment agent, which is preferable from the viewpoint of dispersibility of the filler fine particles. Lowering the dispersibility of the filler particles not only increases the residual potential, but also decreases the transparency of the coating film, causes defects in the coating film, and decreases the wear resistance. It can develop into a big problem to hinder. As the surface treatment agent, a conventionally used surface treatment agent can be used, but a surface treatment agent capable of maintaining the insulating properties of the filler fine particles is preferable. For example, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate coupling agent, a higher fatty acid, etc., or a mixing treatment of these with a silane coupling agent, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Silicone, aluminum stearate, or the like, or a mixture thereof is more preferable from the viewpoint of dispersibility of filler fine particles and image blur.

  The treatment with the silane coupling agent is strongly influenced by image blur, but the influence may be suppressed by performing a mixing treatment of the surface treatment agent and the silane coupling agent. The surface treatment amount varies depending on the average primary particle size of the filler fine particles to be used, but is preferably 3 to 30 wt%, and more preferably 5 to 20 wt%. When the surface treatment amount is less than this, the effect of dispersing the filler fine particles cannot be obtained, and when it is too much, the residual potential is significantly increased. These filler fine particle materials may be used alone or in combination of two or more.

[Solid lubricant supply]
In the present invention, a lubricant supply means for supplying the lubricant to the surface of the photoreceptor is an essential constituent requirement.
An example of the lubricant supply means is shown in FIG.
This lubricant supply means 3C has a fur brush 3B as an application member, a solid lubricant 3A, and a pressure spring 3D for pressing the solid lubricant 3A in the direction of the fur brush 3B. The solid lubricant 3A at this time is a solid lubricant molded into a bar shape. The fur brush 3B has a brush tip abutting on the surface of the photosensitive member, and by rotating around the shaft, the solid lubricant 3A is pumped up to one end of the brush, and is carried and conveyed on the brush to a contact position with the surface of the photosensitive member. Input on the surface of the photoreceptor. Further, even if the solid lubricant 3A is scraped off by the fur brush 3B over time, the solid lubricant 3A is brought into contact with the fur brush 3B at a predetermined pressure by the pressurizing spring 3D so that it does not come into contact with the fur brush 3B. Is pressed. As a result, even a small amount of the solid lubricant 3A is always pumped uniformly to the fur brush 3B.

  Further, a solid lubricant fixing means for improving the fixability of the solid lubricant adhered to the surface of the photoreceptor may be provided. This means includes means for providing a plate such as a cleaning blade by a trailing method, and means for pressing a rubber roll against the photosensitive member. Examples of the solid lubricant 3A include lead oleate, zinc oleate, copper oleate, zinc stearate, cobalt stearate, iron stearate, copper stearate, zinc palmitate, copper palmitate, and zinc linolenate. Fatty acid metal salts, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polytrifluorochloroethylene, dichlorodifluoroethylene, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-oxafluoropropylene copolymer, etc. In particular, metal soaps that are particularly effective in reducing the coefficient of friction of the photoreceptor 1, particularly metal stearates, and more preferably zinc stearate are more preferable.

In the present invention, when the image forming apparatus is an image forming apparatus having an intermediate transfer member, it is preferable that the intermediate transfer member is also provided with a lubricant supply means and the coverage of the lubricant satisfies the following relationship.
Lubricant coverage on the intermediate transfer member <Lubricant coverage on the photoconductor The coverage of the lubricant according to the present invention can be determined by an X-ray photoelectron spectrometer (XPS). According to the XPS analysis method, elements only on the extreme surface of the sample are detected.
Since XPS detects all elements other than hydrogen on the surface of the sample electrode, it is suitable for evaluating the lubricant application state (coverage) on the surface of the photoreceptor. The method of obtaining the coverage is based on the XPS analysis result 1 of the photoreceptor before applying the lubricant and the XPS analysis result 2 of the lubricant itself as basic information. As the coverage ratio increases, the element of interest approaches the XPS analysis result 2 of the lubricant from the XPS analysis result 1 of the photoreceptor, and can be obtained.
For example, when the lubricant is zinc stearate and the photoreceptor is an organic photoreceptor, the lubricant coverage on the photoreceptor can be obtained by paying attention to the lubricant zinc.

When zinc stearate (C ₃₆ H ₇₀ O ₄ Zn) covers the entire surface of the photoconductor, the ratio of elemental zinc to all elements detected by XPS is determined from the ratio of elements other than hydrogen in the molecule of zinc stearate. The ratio is 1 / (36 + 4 + 1) × 100 = 2.44 atm%. When the amount of zinc is 2.44 atm%, the coverage of the lubricant (zinc stearate) can be determined to be 100%. XPS analysis is performed on a photoreceptor with an unknown lubricant coverage, and if the amount of zinc is 1 atm%, the coverage is 1 / 2.44 × 100 = 41%, and if 1.5 atm%, 1 0.5 / 2.44 × 100 = 61% coverage is required.

In the image forming apparatus of the present invention, conventional techniques can be used except that the above-mentioned convex portions are provided on the surface of the photoreceptor and an application mechanism for supplying a solid lubricant to the surface of the photoreceptor.
Hereinafter, techniques applicable to the present invention for the photoreceptor and the image forming apparatus will be described.

FIG. 8 is a cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to the present invention. An undercoat layer 25, a charge generation layer 26, and a charge transport layer 27 are formed in this order on the conductive support 21, and a convex portion 31 is provided on the charge transport layer.
FIG. 9 is a cross-sectional view schematically showing an example of a photoreceptor having still another layer structure of the present invention. A surface layer 28 is provided on the conductive support 21, the undercoat layer 25, the charge generation layer 26, and the charge generation layer 27, and a convex portion is formed on the surface layer.

[Conductive support]
Examples of the conductive support 21 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, and iron, tin oxide, and indium oxide. A film or cylindrical plastic or paper coated by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel, etc., and drawing ironing method or impact ironing method. It is possible to use pipes that have been surface treated by cutting, superfinishing, polishing, or the like after being made into bare pipes by a method such as the Extruded Ironing method, the Extruded Drawing method, or the cutting method.

[Underlayer]
In the electrophotographic photosensitive member used in the present invention, an undercoat layer 24 can be provided between the conductive support and the photosensitive layer. The undercoat layer is provided for the purpose of improving adhesiveness, preventing moire, improving coatability of the upper layer, and preventing charge injection from the conductive support.
The undercoat layer usually contains a resin as a main component. Usually, since the photosensitive layer is applied on the undercoat layer, the resin used for the undercoat layer is preferably a thermosetting resin that is hardly soluble in an organic solvent. In particular, polyurethane, melamine resin, and alkyd-melamine resin are particularly preferable materials because many of them sufficiently satisfy the above purpose. The resin can be used as a coating material which is appropriately diluted with a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone and the like.

In addition, fine particles such as metal or metal oxide may be added to the undercoat layer in order to adjust conductivity and prevent moire. In particular, titanium oxide is preferably used.
The fine particles are dispersed in a ball mill, attritor, sand mill or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone to obtain a coating material in which the dispersion and the resin component are mixed.
The undercoat layer is formed on the support by dip coating, spray coating, bead coating, or the like. If necessary, it is formed by heat curing.
In many cases, the thickness of the undercoat layer is suitably about 2 to 5 μm. When the accumulation of the residual potential of the photoconductor becomes large, it is preferable to set it below 3 μm.

The photosensitive layer in the present invention is preferably a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated.
[Charge generation layer]
Of the layers in the multilayer photoconductor, the charge generation layer 25 will be described. The charge generation layer refers to a part of the laminated photosensitive layer and has a function of generating charges by exposure. This layer is mainly composed of a charge generating substance among the contained compounds. For the charge generation layer, a binder resin may be used as necessary. As the charge generation material, inorganic materials and organic materials can be used.

  Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and amorphous silicon. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms or phosphorus atoms are preferably used.

  On the other hand, as the organic material, known materials can be used, for example, metal phthalocyanines such as titanyl phthalocyanine and chlorogallium phthalocyanine, metal-free phthalocyanines, azulenium salt pigments, squaric acid methine pigments, and symmetrical types having a carbazole skeleton. Alternatively, an asymmetric azo pigment, a symmetric or asymmetric azo pigment having a triphenylamine skeleton, a symmetric or asymmetric azo pigment having a fluorenone skeleton, a perylene pigment, and the like can be given. Among these, metal phthalocyanines, symmetric or asymmetric azo pigments having a fluorenone skeleton, symmetric or asymmetric azo pigments having a triphenylamine skeleton, and perylene pigments have a high quantum efficiency of charge generation, and thus are suitable for the present invention. It is suitable as a material to be used. These charge generation materials may be used alone or as a mixture of two or more.

  Binder resins used as necessary for the charge generation layer include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N- Examples thereof include vinyl carbazole and polyacrylamide. Moreover, the polymeric charge transport material mentioned later can also be used. Of these, polyvinyl butyral is often used and is useful. These binder resins may be used alone or as a mixture of two or more.

Methods for forming the charge generation layer are roughly classified into a vacuum thin film preparation method and a casting method from a solution dispersion system.
Examples of the former method include a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, and a CVD (chemical vapor deposition) method. Can be formed satisfactorily.

  In addition, in order to provide the charge generation layer by the casting method, the above-described inorganic or organic charge generation material is mixed with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, ball mill, attritor. The dispersion may be dispersed by a sand mill or the like, and the dispersion may be diluted appropriately. Among these solvents, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone are preferable because they have a lower environmental impact than chlorobenzene, dichloromethane, toluene, and xylene. The application can be performed by a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer provided as described above is usually about 0.01 to 5 μm.
When it is necessary to reduce the residual potential and increase the sensitivity, these characteristics are often improved by increasing the thickness of the charge generation layer. On the other hand, the chargeability often deteriorates, such as the charge charge retention and space charge formation. From these balances, the thickness of the charge generation layer is more preferably in the range of 0.05 to 2 μm.

  Further, if necessary, low-molecular compounds such as antioxidants, plasticizers, lubricants and ultraviolet absorbers and leveling agents described later can be added to the charge generation layer. These compounds can be used alone or as a mixture of two or more. When a low molecular weight compound and a leveling agent are used in combination, sensitivity deterioration often occurs. For this reason, the amount of these used is generally 0.1 to 20 phr, preferably 0.1 to 10 phr, and the amount of the leveling agent used is suitably about 0.001 to 0.1 phr.

[Charge transport layer]
The charge transport layer refers to a part of the laminated photosensitive layer that functions to inject and transport charges generated in the charge generation layer and to neutralize the surface charge of the photoreceptor provided by charging. The main component of the charge transport layer can be said to be a charge transport component and a binder component that binds the charge transport component.
Examples of materials that can be used for the charge transport material include low molecular weight electron transport materials, hole transport materials, and polymer charge transport materials.

Examples of the electron transporting material include electron accepting materials such as asymmetric diphenoquinone derivatives, fluorene derivatives, and naphthalimide derivatives.
These electron transport materials may be used alone or as a mixture of two or more.

As the hole transport material, an electron donating material is preferably used.
Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, butadiene derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, Examples include styryl anthracene, styryl pyrazoline, phenylhydrazones, α-phenyl stilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, and thiophene derivatives.
These hole transport materials may be used alone or as a mixture of two or more.

Moreover, the polymeric charge transport material represented below can be used. For example, a polymer having a carbazole ring such as poly-N-vinylcarbazole, a polymer having a hydrazone structure exemplified in JP-A-57-78402, and the like exemplified in JP-A-63-285552 The polysilylene polymer to be used, and aromatic polycarbonates exemplified by general formula (1) to general formula (6) of JP-A No. 2001-330973. These polymer charge transport materials can be used alone or as a mixture of two or more. In particular, the exemplified compounds disclosed in JP-A-2001-330973 are useful because of their good electrostatic characteristics.
When polymerized cross-linked resin surface layers are laminated, polymer charge transport materials are less likely to ooze out the components constituting the charge transport layer into the cross-linked resin surface layer compared to low molecular charge transport materials, and the cross-linked resin surface layer is cured. It is a material suitable for preventing defects. In addition, since the charge transport material has high heat resistance due to the high molecular weight, there is little deterioration due to the heat of curing when forming the cross-linked resin surface layer.

Examples of the polymer compound that can be used as the binder component of the charge transport layer include polystyrene, polyester, polyvinyl, polyarylate, polycarbonate, acrylic resin, silicone resin, fluorine resin, epoxy resin, melamine resin, urethane resin, and phenol resin. And thermoplastic or thermosetting resins such as alkyd resins. Of these, polystyrene, polyester, polyarylate, and polycarbonate are useful because many of them have good charge transfer characteristics when used as a binder component of a charge transport component.
These polymer compounds can be used singly or as a mixture of two or more kinds, or as a copolymer composed of two or more of these raw material monomers, and further copolymerized with a charge transport material.

When an electrically inactive polymer compound is used for modifying the charge transport layer, a cardo polymer type polyester having a bulky skeleton such as fluorene, a polyester such as polyethylene terephthalate or polyethylene naphthalate, or a C type polycarbonate is used. Polycarbonate in which the 3,3 ′ portion of the phenol component is alkyl-substituted with respect to a bisphenol-type polycarbonate, polycarbonate in which the geminal methyl group of bisphenol A is substituted with a long-chain alkyl group having 2 or more carbon atoms, biphenyl or biphenyl Polycarbonate having an ether skeleton, polycarbonate having a long chain alkyl skeleton such as polycaprolactone and polycaprolactone (for example, described in JP-A-7-292095), acrylic resin, polystyrene, hydrogenated porcine Diene is effective.
Here, the electrically inactive polymer compound refers to a polymer compound that does not include a chemical structure exhibiting photoconductivity such as a triarylamine structure.

When these resins are used in combination with a binder resin as an additive, the addition amount is preferably 50 wt% or less with respect to the total solid content of the charge transport layer due to restrictions on light attenuation sensitivity.
When a low molecular charge transport material is used, the amount used is 40 to 200 phr, preferably about 70 to 100 phr. When a polymer charge transport material is used, a material in which the resin component is copolymerized in an amount of about 0 to 200 parts by weight, preferably about 80 to 150 parts by weight with respect to 100 parts by weight of the charge transport component is preferably used.

When two or more kinds of charge transport materials are contained in the charge transport layer, it is preferable that the difference in ionization potential is small. Specifically, by setting the difference in ionization potential to 0.10 eV or less, Can be prevented from becoming a charge trap of the other charge transport material.
Regarding the relationship between the ionization potentials, the difference between the charge transporting material contained in the charge transporting layer and the curable charge transporting material described later is preferably 0.10 eV.

In addition, the ionization potential value of the charge transport material in the present invention is a numerical value obtained by measuring by a general method using the atmospheric atmospheric ultraviolet photoelectron analyzer AC-1 manufactured by Riken Keiki Co., Ltd.
In order to satisfy high sensitivity, the charge transport component is preferably added in an amount of 70 phr or more. In addition, α-phenylstilbene compounds, benzidine compounds, butadiene compound monomers, dimers, and polymer charge transport materials having these structures in the main chain or side chain are materials having high charge mobility. Many are useful.

  Examples of the dispersion solvent that can be used in preparing the charge transport layer coating material include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone, ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve, and aromatics such as toluene and xylene. , Halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate. Of these, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone are preferable because they have a lower environmental impact than chlorobenzene, dichloromethane, toluene, and xylene. These solvents can be used alone or in combination.

  The charge transport layer can be formed by dissolving or dispersing a mixture or copolymer containing a charge transport component and a binder component as main components in an appropriate solvent, and applying and drying the mixture. As the coating method, a dipping method, a spray coating method, a ring coating method, a roll coater method, a gravure coating method, a nozzle coating method, a screen printing method, or the like is employed.

  Furthermore, low-molecular compounds such as antioxidants, plasticizers, lubricants, ultraviolet absorbers and leveling agents described later can be added to the charge transport layer. These compounds can be used alone or as a mixture of two or more. When a low molecular weight compound and a leveling agent are used in combination, sensitivity deterioration often occurs. For this reason, the amount of these used is generally 0.1 to 20 phr, preferably 0.1 to 10 phr, and the amount of the leveling agent used is suitably about 0.001 to 0.1 phr.

  This charge transport layer may be employed as a surface layer, and a protective layer may be laminated on the charge transport layer as necessary. The film thickness of the charge transport layer is practically about 10 to 40 μm, more preferably about 15 to 30 μm for the purpose of ensuring the required sensitivity and charging ability.

<Image forming apparatus>
Next, the electrophotographic method and the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 10 is a schematic diagram for explaining the electrophotographic process and the image forming apparatus of the present invention, and the following examples also belong to the category of the present invention.

The photoconductor (10) rotates in the direction of the arrow in FIG. 7, and there are a charging member (11), an image exposure member (12), a developing member (13), and a transfer member (16) around the photoconductor (10). ), A cleaning member (17), a charge removal member (18), and the like are disposed. The cleaning member (17) and the charge removal member (18) may be omitted.
The operation of the image forming apparatus is basically as follows. The charging member (11) charges the surface of the photoreceptor (10) almost uniformly. Subsequently, image light writing corresponding to the input signal is performed by the image exposure member (12) to form an electrostatic latent image. Next, the electrostatic latent image is developed by the developing member (13), and a toner image is formed on the surface of the photoreceptor. The formed toner image is transferred onto the transfer paper (15) sent to the transfer site by the transport roller (14) by the transfer member. This toner image is fixed on the transfer paper by a fixing device (not shown). Part of the toner that has not been transferred to the transfer paper is cleaned by the cleaning member (17). Next, the charge remaining on the photoreceptor is neutralized by the neutralizing member (18), and the process proceeds to the next cycle.

  As shown in FIG. 10, the photoconductor (10) has a drum shape, but may have a sheet shape or an endless belt shape. As the charging member (11) and the transfer member (16), in addition to corotron, scorotron, solid state charger (solid state charger), a roller-shaped charging member or a brush-shaped charging member is used. Are all usable.

On the other hand, light sources such as the image exposure member (12) and the charge removal member (18) include fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LD), and electroluminescence (EL). ) And other luminescent materials can be used. Among these, a semiconductor laser (LD) and a light emitting diode (LED) are mainly used.
Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

The light source or the like irradiates the photoconductor (10) with light by providing a transfer process, a static elimination process, a cleaning process, or a pre-exposure process using light irradiation together. However, the exposure of the photoconductor (10) in the static elimination process has a large influence of fatigue on the photoconductor (10), and may cause a decrease in charge and an increase in residual potential.
Therefore, there is a case where it is possible to eliminate static electricity by applying a reverse bias in the charging process or cleaning process instead of static elimination by exposure, which may be effective from the viewpoint of enhancing the durability of the photoreceptor.

When the electrophotographic photosensitive member (10) is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.
A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.

  Among the contaminants that adhere to the surface of the photoconductor, discharge substances generated by charging and external additives contained in the toner are easy to pick up the effects of humidity and cause abnormal images. Paper powder is one of the causative substances, and when they adhere to the photoreceptor, abnormal images are more likely to occur, as well as a tendency to reduce wear resistance and cause uneven wear. Is seen. Therefore, it is more preferable from the viewpoint of high image quality that the photoconductor and the paper are not in direct contact for the above reason.

  The toner developed on the photoreceptor (10) by the developing member (13) is transferred to the transfer paper (15), but not all is transferred, and the toner remaining on the photoreceptor (10). Also occurs. Such toner is removed from the photoreceptor (10) by the cleaning member (17). As the cleaning member, a known member such as a cleaning blade or a cleaning brush is used. Moreover, both may be used together.

  The photoconductor according to the present invention can be applied to a small-diameter photoconductor because high photosensitivity and high stability are realized. Therefore, as an image forming apparatus or method for using the above photoreceptor more effectively, each developing unit corresponding to a plurality of colors of toner is provided with a plurality of corresponding photoreceptors, thereby performing parallel processing. It is very effectively used in a so-called tandem type image forming apparatus. The tandem image forming apparatus includes at least four color toners of yellow (C), magenta (M), cyan (C), and black (K) required for full-color printing and a developing unit that holds them. Further, by providing at least four photoconductors corresponding to them, full-color printing can be performed at an extremely high speed as compared with a conventional image forming apparatus capable of full-color printing.

FIG. 11 is a schematic diagram for explaining the tandem-type full-color electrophotographic apparatus of the present invention, and the following modifications also belong to the category of the present invention.
In FIG. 11, photoconductors (10C (cyan)), (10M (magenta)), (10Y (yellow)), and (10K (black)) are drum-like photoconductors (10), and these photoconductors. (10C, 10M, 10Y, 10K) rotate in the direction of the arrow in the figure, around which at least the charging members (11C, 11M, 11Y, 11K), the developing members (13C, 13M, 13Y, 13K), Cleaning members (17C, 17M, 17Y, 17K) are arranged.

From the back side of the photoreceptor (10) between the charging member (11C, 11M, 11Y, 11K) and the developing member (13C, 13M, 13Y, 13K), laser light (12C, 12M, 12Y, 12K) is irradiated, and electrostatic latent images are formed on the photoconductors (10C, 10M, 10Y, 10K).
Then, four image forming elements (20C, 20M, 20Y, 20K) centering on such a photoreceptor (10C, 10M, 10Y, 10K) are along a transfer conveyance belt (25) which is a transfer material conveyance unit. Are juxtaposed.

  The transfer / conveying belt (19) is disposed between the developing member (13C, 13M, 13Y, 13K) of each image forming element (20C, 20M, 20Y, 20K) and the cleaning member (17C, 17M, 17Y, 17K). A transfer member (16C) for applying a transfer bias to the surface (rear surface) which is in contact with the photoconductor (10C, 10M, 10Y, 10K) and contacts the back side of the photoconductor (10) side of the transfer conveyance belt (19). , 16M, 16Y, 16K). Each of the image forming elements (20C, 20M, 20Y, 20K) is different in toner color inside the developing device, and the other components have the same configuration.

  In the color electrophotographic apparatus having the configuration shown in FIG. 11, the image forming operation is performed as follows. First, in each of the image forming elements (20C, 20M, 20Y, and 20K), the charging member (11C, 11M, 11Y, and 11K) in which the photosensitive member (10C, 10M, 10Y, and 10K) rotates along with the photosensitive member 10 is rotated. ), And then an electrostatic image corresponding to the image of each color to be created by laser light (12C, 12M, 12Y, 12K) by an exposure unit (not shown) arranged outside the photoconductor (10). A latent image is formed.

  Next, the latent image is developed by a developing member (13C, 13M, 13Y, 13K) to form a toner image. The developing members (13C, 13M, 13Y, and 13K) are developing members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively. 10M, 10Y, and 10K) are overlaid on the transfer belt (19).

  The transfer paper (15) is sent out from the tray by the paper supply roller (21), temporarily stopped by the pair of registration rollers (22), and sent to the transfer member (23) in synchronization with the image formation on the photosensitive member. It is done. The toner image held on the transfer belt (19) is transferred onto the transfer paper (15) by an electric field formed by a potential difference between the transfer bias applied to the transfer member (23) and the transfer belt (19). . The toner image transferred onto the transfer paper is conveyed, the toner is fixed onto the transfer paper by the fixing member (24), and is discharged to a paper discharge unit (not shown). Further, residual toner that is not transferred by the transfer unit and remains on the photosensitive members (10C, 10M, 10Y, and 10K) is collected by cleaning members (17C, 17M, 17Y, and 17K) provided in the respective units. The

The intermediate transfer method as shown in FIG. 11 is particularly effective for an image forming apparatus capable of full-color printing. By forming a plurality of toner images once on an intermediate transfer body and transferring them to paper at once, It is easy to control the color shift and is effective for high image quality.
The intermediate transfer member includes various materials or shapes such as a drum shape and a belt shape. In the present invention, any conventionally known intermediate transfer member can be used. It is effective and useful for achieving high quality or high image quality.

  In the example of FIG. 11, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism that stops the image forming elements (20C, 20M, 20Y) other than black.

The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge.
As shown in FIG. 10, the process cartridge includes a photoconductor (10), a charging member (11), an image exposure member (12), a developing member (13), a transfer member (16), a cleaning member. It is one apparatus (part) including the member (17) and the charge removal member.

The above-described tandem image forming apparatus can transfer a plurality of toner images at a time, so that high-speed full-color printing is realized.
However, since at least four photoconductors are required, an increase in the size of the apparatus is unavoidable, and depending on the amount of toner used, there is a difference in the wear amount of each photoconductor, thereby reproducing the color. There are many problems such as a decrease in performance and occurrence of abnormal images.
On the other hand, the photosensitive member according to the present invention can be applied to a small-diameter photosensitive member by realizing high photosensitivity and high stability, and the influence of increase in residual potential, sensitivity deterioration, etc. is reduced. Even if the amount of the photoconductor used is different, the difference in residual potential and sensitivity over time is small, and a full color image having excellent color reproducibility can be obtained even when used repeatedly for a long time.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Note that “parts” used in the examples all represent parts by weight.

[Examples 1 to 12 and Comparative Examples 1 to 6]
(Preparation of photoconductor A)
Apply an undercoat layer coating solution of the following formulation to an Al support (outer diameter 40 mmφ) by a dipping method so that the film thickness after drying is 3.5 μm, and heat dry at 130 ° C. for 20 minutes. And an undercoat layer was formed.

・ Coating liquid for undercoat layer 6 parts alkyd resin (Beckosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
Titanium oxide 40 parts (CR-EL: Ishihara Sangyo)
50 parts of methyl ethyl ketone

On this undercoat layer, a charge generation layer coating solution containing a bisazo pigment having the following structure was dip coated, and dried at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.2 μm.
-Coating solution for charge generation layer 2.5 parts of bisazo pigment with the following structure
Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part Cyclohexanone 200 parts Methyl ethyl ketone 80 parts

On this charge generation layer, dip coating was performed using a charge transport layer coating liquid having the following formulation, followed by heating and drying at 130 ° C. for 20 minutes to obtain a charge transport layer having a thickness of 22 μm.
・ Coating solution for charge transport layer 10 parts of bisphenol Z type polycarbonate 10 parts of low molecular charge transport material with the following structure
Tetrahydrofuran 80 parts 1% silicone oil in tetrahydrofuran 0.2 parts

Next, a convex forming liquid having the following prescription is put into a continuous ink jet coating apparatus (nozzle diameter 30 μm) as shown in FIG. The convex portion forming liquid was deposited on the 333 μm pitch at regular intervals, and touch-dried for 10 minutes.
・ Protrusions forming liquid Trifunctional or higher radical polymerizable monomer having no charge transport structure 9 parts Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 382, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
9 parts of radically polymerizable compound having a charge transporting structure (2- [4 ′-(di-p-tolyl-amino) -biphenyl-4-yl] -ethyl acrylate)
Photoinitiator 2 parts 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

UV curing was performed while rotating the drum at a distance of 120 mm from the drum and the UV curing lamp. The illuminance of the UV curing lamp at this position was 550 mW / cm ² (UV integrated light meter UIT-150, measured value by Ushio Inc.). The drum rotation speed was 25 rpm. When performing UV curing, UV curing was performed continuously for 3 minutes by circulating water at 30 ° C. in an aluminum drum. Then, it heat-dried at 130 degreeC for 30 minutes.
As described above, a photoconductor having the structure shown in FIG. 8 was obtained.
As a result of observing the surface of the prepared photoreceptor with an objective lens 20 times using a 3CCD real color confocal microscope (confocal) microscope OPTELICS H1200 (Lasertec), the diameter of the convex portion is 50 μm and the height of the convex portion is 1. A photosensitive member A having a convex portion of 0.5 μm and 9 convex portions per 1 mm square was obtained.

(Preparation of photoconductors B to R )
Fifteen photoconductors up to the charge transport layer were formed in the same manner as the photoconductor A up to the conductive support, the undercoat layer, the charge generation layer, and the charge transport layer.
Next, the convex forming liquid was deposited on the charge transport layer under the conditions shown in Table 1 to obtain photoreceptors B to P.

  About the obtained photoreceptor, the shape of the convex portion was observed using the 3CCD real color confocal (confocal) microscope OPTELICS H1200 (Lasertec) similarly to the photoreceptor A. The results are shown in Table 2.

The photoconductor obtained as described above was incorporated into an image forming apparatus having the structure shown in FIG. 10, and the cleaning performance and abnormal images were investigated.
As the lubricant application mechanism, the lubricant supply means having the structure shown in FIG. 7 is disposed downstream of the cleaning device 17 of the apparatus shown in FIG. 10 to apply the lubricant onto the photosensitive member.
As the lubricant at this time, zinc stearate was used.
Other imaging conditions were as follows.
As the toner, a polymerized toner having a circularity of 0.985 and a volume average particle size of 4.3 μm was used. The cleaning method is a blade cleaning method, the blade is polyurethane rubber, rubber hardness (Shore A) 72, the blade contact method is a counter, the cleaning angle is 80 °, the biting amount is 0.8 mm, and the contact pressure is 0.2 N / cm.
The charging method was a DC roller charging method.
The abnormal images were visually judged with blank images, halftone images, and solid black images.
The slip-through property was judged according to the evaluation criteria described below from the toner amount of toner that passed through the cleaning blade collected on the felt member arranged immediately downstream of the cleaning blade after 10 images of 5% were formed.
○: No toner stains △: Slightly toner stains ×: Many toner stains are difficult to use repeatedly Table 3 shows the evaluation results.

As is clear from the above results, in order to clean a small particle size and spherical polymer toner,
Lubricant supply means is provided for the photoconductor, the longest diameter is 10 to 500 μm on the surface of the photoconductor, the height of the convex portion is 0.5 to 5 μm, and the number of convex portions is the surface layer of the photoconductor. It was effective to form 2 to 5000 convex portions per 1 mm square on the surface.

[Example 13]
Four photoconductors similar to the photoconductor A were prepared and incorporated in the image forming units of the respective colors of the image forming apparatus configured as shown in FIG. 11 (20C, 20M, 20Y, 20K). Lubricant coating apparatus having a mechanism (mechanism in which a solid lubricant is pressed against a brush in contact with the photosensitive member) similar to that shown in FIG. 10 immediately downstream of each cleaning member (17K, 17C, 17M, 17Y) Arranged. At this time, zinc stearate was used as the lubricant. As described above, an image forming apparatus of Example 13 was obtained.

[Example 14]
An image forming apparatus was obtained in exactly the same manner as in Example 13 except that 2 parts of Al ₂ O ₃ (average particle size 0.3 μm) was added to the convex forming liquid.
[Example 15]
An image forming apparatus was obtained in the same manner as in Example 13 except that the binder of the convex portion forming liquid was changed to a thermosetting polyurethane resin.
[Example 16]
An image forming apparatus was obtained in the same manner as in Example 15 except that 2 parts of polymethyl methacrylate fine particles (average particle size 0.2 μm) were added to the convex forming liquid.

[Example 17]
An image forming apparatus was obtained in the same manner as in Example 14 except that the solid lubricant was changed to tetrafluoroethylene.
[Example 18]
An image forming apparatus was obtained in the same manner as in Example 14 except that the solid lubricant was changed to copper oleate.
[Example 19]
An image forming apparatus was obtained in the same manner as in Example 14 except that the solid lubricant was changed to polyvinylidene fluoride.

[Example 20]
A lubricant application mechanism similar to that shown in FIG. 10 is attached to the intermediate transfer belt of the image forming apparatus according to the fourteenth embodiment. Further, in order to make the supply amount of the lubricant more than the supply amount on the photoreceptor side, the pressing force of the lubricant is applied to the photoreceptor. An image forming apparatus having a pressure doubled by the lubricant pressing force was obtained.
The lubricant coverage at this time was 80% of the photoconductor and 90% of the intermediate transfer belt as determined from the amount of zinc atoms by XPS.

[Example 21]
An image forming apparatus having the same configuration as that of Example 20 is prepared, and the pressing force of the lubricant is reduced to ½ of the pressing force to the photosensitive member in order to reduce the amount of lubricant supplied to the intermediate transfer belt. Got.
The lubricant coverage at this time was 80% of the photoreceptor and 60% of the intermediate transfer belt when calculated from the amount of zinc atoms by XPS.

[Comparative Example 7]
The image forming apparatus was obtained by incorporating the photoconductor U formed up to the charge transport layer of the photoconductor A (without forming a convex portion) into the system of FIG.
[Comparative Example 8]
An image forming apparatus was obtained in the same manner as Comparative Example 7 except that a device for supplying a lubricant to the photosensitive member was disposed. The lubricant was zinc stearate.
[Comparative Example 9]
An image forming apparatus was obtained in the same manner as in Comparative Example 7 except that the photoreceptor R was used.

The configuration of the image forming apparatus is summarized in Table 4 above.

Each of the obtained image forming apparatuses was evaluated for cleaning properties (the above-mentioned slip-through properties). The results are shown in Table 5.

When the image forming apparatus of Example 14 was repeatedly used and 1000K copies were made, the image quality was the same as in the initial stage, the cleaning property (slip-through property) was not changed, and the photoconductor wear was a convex portion and a portion other than the convex portion. Both were hardly worn and found to be excellent in abrasion resistance.
Further, it was found that the amount of decrease in the lubricant was sufficiently small as compared with Comparative Example 8 in which no protrusion was formed, and the lubricant was applied and maintained with high efficiency.

According to the present invention, the convex portions provided on the surface of the photosensitive member can solve the side effects at the initial stage of cleaning such as blade turning and chattering, and cleaning properties of polymerized toner, spherical toner, and small particle size toner, which are becoming mainstream nowadays. Since the image forming apparatus having excellent transferability is obtained and the lubricant is applied to the photoconductor, it is possible to suppress wear of the non-convex portion due to charging fatigue or friction fatigue, and image due to wear of the non-convex portion. An excellent image forming apparatus capable of solving the above background stain and maintaining high image quality over a long period of time can be obtained.
In addition, the lubricant application brush removes the lubricant while vibrating due to the vibration caused by the contact of the convex part of the photoreceptor, and applies the lubricant to the photoreceptor. Can be achieved.

(Fig. 7)
31 Photoconductor 35 Cleaning blade 3A Solid lubricant 3B Fur brush 3C Lubricant supply means 3D Pressure spring

(Figs. 8 and 9)
21 conductive support 25 subbing layer 26 charge generation layer 27 charge transport layer 28 surface layer 31 convex portion

(Fig. 10)
DESCRIPTION OF SYMBOLS 10 Photoconductor 11 Charging member 12 Image exposure member 13 Developing member 14 Conveying roller 15 Transfer paper 16 Transfer member 17 Cleaning member 18 Static elimination member

(Fig. 11)
10 photoconductor 10C, 10M, 10Y, 10K photoconductor 11C, 11M, 11Y, 11K charging member 12C, 12M, 12Y, 12K laser beam 13C, 13M, 13Y, 13K developing member 15 transfer paper 16C, 16M, 16Y, 16K transfer Member 17C, 17M, 17Y, 17K Cleaning member 19 Transfer conveying belt 20C, 20M, 20Y, 20K Image forming element 21 Feed roller 22 Registration roller 23 Transfer member 24 Fixing member 25 Transfer conveying belt

Japanese Patent No. 2520270 Japanese Patent No. 3585197 JP 2001-166521 A Japanese Patent Publication No. 6-82221 JP 2002-196523 A JP 2001-66814 A JP 2007-233356 A Japanese Patent No. 3963473 JP 2007-233359 A JP 2009-31499 A

Claims (8)

An image forming apparatus comprising: a photosensitive member having an independent convex portion formed of a material different from the surface layer on the surface layer; and a lubricant supply unit that supplies a lubricant to the photosensitive member. The protrusions formed on the surface have a longest diameter of 10 to 500 μm, a height of the protrusions of 0.5 to 5 μm, and the number of protrusions is the unit surface area of the surface layer of the photoreceptor ( An image forming apparatus having ^{2 to} 5000 per mm ² ).   The image forming apparatus according to claim 1, wherein the lubricant is a metal soap.   The image forming apparatus according to claim 1, wherein the lubricant supplying unit applies the lubricant downstream of at least one cleaning element. The image forming apparatus is an image forming apparatus having an intermediate transfer member, wherein the intermediate transfer member also has a lubricant supply means, and the coverage of the lubricant satisfies the following relationship. The image forming apparatus according to claim 3.
Lubricant coverage on intermediate transfer member <Lubricant coverage on photoreceptor   5. The image forming apparatus according to claim 1, wherein the binder resin of the surface layer is a thermoplastic resin, and the binder resin of the convex portion includes a curable resin.   The image forming apparatus according to claim 1, wherein the convex portion includes an inorganic pigment.   The image forming apparatus according to claim 1, wherein the convex portion includes resin particles.   The image forming apparatus according to claim 1, wherein the convex portion contains a charge transport material.