JP2006039019A - Organic photoreceptor, and process cartridge and image forming apparatus using organic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor used for an image forming apparatus of a cleaner-less process, and a process cartridge and an image forming apparatus using the organic photoreceptor. <P>SOLUTION: The inorganic photoreceptor is used for the image forming apparatus which has the inorganic photoreceptor, a charging means, a latent image forming means for forming an electrostatic latent image on the inorganic photoreceptor by performing image exposure using a semiconductor laser or light emitting diode of 350 to 500 mm in oscillation wavelength, a developing means, and a transfer means for transferring a toner image on a transfer material, and repetitively forms electrophotographic images by circulating the inorganic photoreceptor after the transfer of the toner image to the charging means without subjecting the inorganic photoreceptor to a cleaning means in contact with the surface of the inorganic photoreceptor. The inorganic photoreceptor has a surface layer containing fluororesin particulate having average primary grain size of ≥0.02 to ≤0.20 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic photoreceptor used in the field of copying machines and printers, a process cartridge and an image forming apparatus using the organic photoreceptor.

  Organic photoconductors have great advantages such as wide selection of materials, excellent environmental suitability and low production costs compared to inorganic photoconductors such as selenium photoconductors and amorphous silicon photoconductors. In recent years, electrophotographic photoreceptors have become the mainstream in place of inorganic photoreceptors.

  On the other hand, in the image forming method based on the Carlson method, a charged, electrostatic latent image is formed on an organic photoreceptor, and a toner image is formed. Then, the toner image is transferred to a transfer paper and remains on the organic photoreceptor. The process of removing the toner with a cleaning device is repeated to produce a large number of electrophotographic images.

  As the cleaning device (means), scraping with a blade is mainly used, and residual toner on the surface of the organic photoreceptor is scraped off with the blade. It is sent out to a toner collection box (not shown) using a screw or the like.

  The above-described blade scraping type cleaner requires a recovery toner collection box or a space for recycling, and the toner collection box must be monitored for fullness. In addition, the surface of the organic photoreceptor is easily damaged by the blade, and there is a problem that the life of the electrophotographic photoreceptor is shortened. Therefore, research on processes that do not use contact cleaners (hereinafter also referred to as cleaner-less processes) is being conducted. For example, an attempt has been made to install a process for magnetically or electrically attracting residual toner adhering to the surface of the electrophotographic photosensitive member immediately before the developing roller, or to increase the toner transfer efficiency in the transfer process and eliminate the residual toner.

  In recent years, it has been studied to use a contact charging method that does not use a corona discharger as a method for charging an organic photoreceptor. Specifically, a voltage is applied to a brush or a conductive roller that is a charging member to bring it into contact with a photosensitive member that is a member to be charged, and the surface of the photosensitive member is charged to a predetermined potential. If such a contact charging method is used, the voltage can be lowered and the amount of ozone generated can be reduced as compared with a non-contact charging method using a corona discharger.

  The contact charging method is a method of applying a direct current or a direct current voltage on which an alternating current is superimposed on a charging member having a resistance of about 102 to 1010 Ω · cm to the photosensitive member and applying pressure to the photosensitive member to apply electric charge. . Since this charging method is performed by discharging from the charging member to the member to be charged in accordance with Paschen's law, charging is started by applying a voltage equal to or higher than a certain threshold value. In this contact charging method, compared with the corona charging method, the voltage applied to the charging member is lowered, and the generation amount of ozone and nitrogen oxides is reduced.

  An organic photoreceptor having improved toner releasability has been proposed as an organic photoreceptor suitable for these cleaner-less processes and contact charging systems (Patent Document 1). In order to improve the releasability of the toner and increase the transfer efficiency of the toner, an organic photoreceptor in which the surface layer of the organic photoreceptor contains fluorine-containing resin particles is used. However, in the cleaner-less process, the organic photoreceptor having the fluororesin particles reported so far on the surface is not subjected to strong rubbing on the surface of the photoreceptor by the cleaning blade. Agent components are likely to adhere. That is, gas components such as ozone and NOx and external additive components of toner are likely to adhere to the interface between the fluorine-containing resin particles and the binder on the surface layer of the photoreceptor, and this causes image blurring and dash marks (comet Small streaky image) is likely to occur, and the sharpness of character images and halftone images tends to deteriorate.

  In addition, an image forming apparatus using an organic photoreceptor is required to be capable of outputting a high-definition digital image in response to an increase in demand for a printer or the like as a computer image output terminal in recent years. In response to such demands, it has been proposed to form a high-density digital image using a short-wavelength laser beam as an exposure light source (Patent Document 2). Further, purple to blue short wavelength LDs and LEDs having an oscillation wavelength of 400 to 500 nm are provided on the market as image exposure light sources. Using these short wavelength light sources, it is possible to form a latent image by reducing the spot diameter of the laser beam on the photoreceptor. However, even if these laser beam diameters are reduced, the above-mentioned photoconductors in which the dash marks and image blur are likely to occur do not form independent dots of the laser beam on the organic photoconductor. The improvement effect of is not fully demonstrated.

In addition, as a means for improving the adhesion of foreign matter to the surface of the photoreceptor, a technique using fluororesin fine particles having a low crystallinity (X-ray diffraction pattern peak half width of 0.28 or more) has been reported. (Patent Document 3). However, fluororesin fine particles with low crystallinity tend to adhere to each other, and the dispersion stability is low in the coating dispersion, causing the particles to aggregate to form coarse aggregated particles. As a result, it is difficult to form a surface layer having uniform characteristics, the above-described dash marks and image blurring occur, and the halftone image becomes rough.
JP 2002-278096 A JP 2000-250239 A JP-A-8-328287

  An object of the present invention is to solve the above-mentioned problems of an organic photoreceptor used in an image forming apparatus of a cleaner-less process, and more specifically, an organic photoreceptor having a surface layer containing conventional fluororesin fine particles. In order to solve the above-mentioned problems, it is possible to provide an organic photoreceptor capable of preventing the occurrence of dash marks and image blurring and reproducing a dot image using a short wavelength laser with high accuracy. A process cartridge and an image forming apparatus using the same.

We prevent the above-mentioned problems with organic photoreceptors used in cleaner-less image forming devices, that is, the occurrence of dash marks and image blurring, and reproduce dot images using short-wavelength lasers with high accuracy. As a result of repeated studies to obtain an organic photoreceptor that can be used, the surface layer of the organophotoreceptor has a small particle size and a low dispersion degree of fluorine-containing resin fine particles contained in a uniform dispersion. The adhesion of the fluororesin fine particles can be increased and the variation in contact angle can be reduced. As a result, the adsorption of the active gas or toner to the surface layer of the inorganic external additive is suppressed, and the scattering of the short wavelength laser beam It was found that a high-definition halftone image can be formed by preventing occurrence of dash marks and image blur, and the present invention has been completed. In particular, it is possible to form a surface layer having a uniform surface energy by improving the dispersibility of the fluorine-containing resin fine particles by using low-crystalline and small-sized fluorine-containing resin fine particles contained in the surface layer. The present invention has been completed. That is, the present invention is achieved by having the following configuration.
(Claim 1)
A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. In the organic photoreceptor used in the image forming apparatus for repeatedly forming the electrophotographic image by circulating the organic photoreceptor after the transfer to the charging means without being attached to the cleaning means contacting the surface of the organic photoreceptor, the average primary particle size is 0. An organic photoreceptor having a surface layer containing fluororesin fine particles having a size of 0.02 μm or more and less than 0.20 μm.
(Claim 2)
A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. In the organic photoreceptor used in the image forming apparatus for repeatedly forming the electrophotographic image by circulating the organic photoreceptor after the transfer to the charging means without being attached to the cleaning means contacting the surface of the organic photoreceptor, the average primary particle size is 0. An organic sensation characterized by containing a fluororesin fine particle of 0.02 μm or more and less than 0.20 μm, having a surface layer having a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 °. Light body.
(Claim 3)
3. The organic photoconductor according to claim 1, wherein the organic photoconductor is composed of a charge generation layer and a plurality of charge transport layers on a conductive support, and the uppermost charge transport layer is a surface layer. body.
(Claim 4)
The organophotoreceptor according to any one of claims 1 to 3, wherein the degree of crystallinity of the fluororesin fine particles is 40% or more and less than 90%.
(Claim 5)
The organophotoreceptor according to claim 1, wherein the surface layer contains a siloxane-modified polycarbonate.
(Claim 6)
The organophotoreceptor according to claim 1, wherein the surface layer contains an antioxidant.
(Claim 7)
A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. 7. A process cartridge for use in an image forming apparatus for circulating an organic photoreceptor after transfer to a charging means without being attached to a cleaning means that contacts the surface of the organic photoreceptor to repeatedly form an electrophotographic image. The organic photoreceptor according to any one of the above and at least one of a charging unit, a latent image forming unit, a developing unit, a transfer unit, and a charge eliminating unit are integrally supported and attached to the main body of the image forming apparatus. A process cartridge which is a freely mountable.
(Claim 8)
A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. In the image forming apparatus in which the transferred organic photoconductor is circulated to the charging unit without being attached to the cleaning unit that contacts the surface of the organic photoconductor to repeatedly form an electrophotographic image, the organic photoconductor has an average primary particle size. An image forming apparatus comprising a surface layer containing fluororesin fine particles of 0.02 μm or more and less than 0.20 μm.

  By using the organophotoreceptor of the present invention in an image forming apparatus of a cleaner-less process, dash marks and image blur that have been problems in the past can be improved, and a high-definition halftone image can be formed. In addition, a process cartridge and an image forming apparatus using the organic photoreceptor can be provided.

Hereinafter, the present invention will be described in detail.
The organic photoreceptor of the present invention is subjected to image exposure using a charging means for charging the organic photoreceptor and the organic photoreceptor, and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm. A latent image forming means for forming an electrostatic latent image; a developing means for visualizing the electrostatic latent image with toner to form a toner image on the organic photoreceptor; and a transfer means for transferring the toner image to a transfer material; An organic photoreceptor for use in an image forming apparatus for repeatedly forming an electrophotographic image by circulating the organic photoreceptor after transfer of the toner image to a charging means without being attached to a cleaning means that contacts the surface of the organic photoreceptor And a surface layer containing fluororesin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm.

  Further, the organic photoreceptor of the present invention is subjected to image exposure using a charging means for charging the organic photoreceptor and the organic photoreceptor, and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm. A latent image forming unit that forms an electrostatic latent image on the surface, a developing unit that visualizes the electrostatic latent image with toner and forms a toner image on the organic photoreceptor, and a transfer that transfers the toner image to a transfer material. And an organic photoreceptor used for an image forming apparatus for repeatedly forming an electrophotographic image by circulating the organic photoreceptor after transfer of the toner image to a charging means without being attached to a cleaning means contacting the surface of the organic photoreceptor. It is a photoconductor and contains fluorine-containing resin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle of ± 2.0 °. The surface layer of It is characterized by having.

  The organophotoreceptor of the present invention has the structure as described above, so that dash marks and image blurs that are likely to occur in an image forming apparatus that performs image exposure using a short-wavelength laser beam or a light-emitting diode in a cleaner-less process. Generation of an electrophotographic image of a halftone image with good sharpness can be prevented.

  That is, the fluororesin fine particles have poor dispersion uniformity as described above, and it has been difficult to form a uniform and smooth film without aggregates. In other words, the fluorine-containing resin fine particles having a small particle size easily form aggregated particles, and in the surface-layer organic photoreceptor containing the aggregated particles, the contact angle varies greatly. When applied to a cleaner-less process, dash marks and image blurs. Is likely to occur. As a result, a high-definition halftone image produced with a short-wavelength laser beam or a light-emitting diode could not be visualized, but the average primary particle size was not less than 0.02 μm and less than 0.20 μm. The organic photoreceptor on the surface layer that improves the dispersibility of the fluororesin fine particles, has a contact angle with water of 90 ° or more, and has a contact angle variation of ± 2.0 ° can cause dash marks and image blurring. Therefore, an electrophotographic image having a good halftone image can be formed.

  The surface layer having the characteristics of the present invention comprises a dispersion of fluororesin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm, a low-boiling solvent having good dispersibility, preferably 120 at atmospheric pressure. By dispersing using an organic solvent (eg, THF, ethanol, toluene, dichloroethane, etc.) having a boiling point of 0 ° C. or lower, a stable dispersion can be produced while suppressing the cohesiveness between the fluororesin fine particles. . At the same time, the dispersion liquid is used as a coating liquid to form a surface layer using a coating liquid supply type coating apparatus and then dried to prevent aggregation of the fluororesin fine particles in the surface layer. A surface layer with good dispersibility can be formed. As a result, it is possible to form an organic photoreceptor having a surface layer with a uniform surface energy with small variation in contact angle, preventing the occurrence of dash marks and image blurring, and an electrophotographic image with good halftone image sharpness. It is possible to produce an organic photoreceptor capable of forming

  The coating liquid supply type coating apparatus means a coating apparatus that supplies and coats a coating liquid necessary for layer formation on a conductive support, and includes, for example, a slide hopper type coating apparatus, an extrusion type coating apparatus, and a spray. A coating apparatus etc. are mentioned. Such a coating liquid supply type coating apparatus forms a surface layer in one way without causing the dispersion to stay in the coating apparatus, as compared with immersion coating in which a conductive support is immersed in the coating liquid. Therefore, the dispersed particles of the fluorine-containing resin fine particles can form a uniform surface layer with less aggregation of the fluorine-containing resin fine particles without repeatedly receiving the aggregation share in the dispersion. Moreover, since a dispersion can be prepared for each photoconductor production, aggregation of the dispersion over time can be prevented, and when forming the surface layer, it can be applied without dissolving the lower layer already formed on the conductive support, Even during coating and drying, there is little aggregation of the fluororesin fine particles, and a surface layer having uniform dispersibility can be formed.

  Among the above coating liquid supply type coating apparatuses, the coating method using a slide hopper type coating apparatus is most suitable when the above-described dispersion using a low boiling point solvent is used as the coating liquid, and is a cylindrical photoconductor. In this case, the coating is preferably performed using a circular slide hopper type coating apparatus described in detail in JP-A No. 58-189061 and the like.

  The circular slide hopper type coating apparatus will be briefly described below.

  In the present invention, the coating liquid in which the fluororesin fine particles are dispersed is advantageously applied using a circular slide hopper type coating apparatus. As an example of a circular slide hopper type coating device, for example, as shown in a longitudinal sectional view in FIG. 1, the cylindrical base materials 251A and 251B vertically stacked along the center line XX are continuously raised in the direction of the arrow. The coating liquid L is applied by a portion (abbreviated as an application head) 260 that directly surrounds the periphery of the substrate 251 and is directly related to the application of the slide hopper type application device. The base material may be a hollow drum, for example, an aluminum drum, a plastic drum, or a seamless belt type base material. As shown in FIG. 2, a narrow coating liquid distribution slit (abbreviated as a slit) 262 having a coating liquid outlet 261 that opens toward the substrate 251 is formed in the coating head 260 in the horizontal direction. The slit 262 communicates with the annular coating liquid distribution chamber 263, and the coating liquid L in the storage tank 254 is supplied to the annular coating liquid distribution chamber 263 via the supply pipe 264 by the pressure feed pump 255. Yes. On the other hand, on the lower side of the coating liquid outlet 261 of the slit 262, there is formed a slide surface 265 that is continuously inclined and formed to end with a dimension slightly larger than the outer dimension of the substrate. . Furthermore, a lip-like part (bead; liquid reservoir part) 266 extending downward from the end of the slide surface 265 is formed. In application by such an applicator, when the coating liquid L is pushed out from the slit 262 and flows down along the slide surface 265 in the process of pulling up the substrate 251, the photosensitive liquid reaching the end of the slide surface becomes the end of the slide surface. A bead is formed between the outer peripheral surface of the substrate 251 and then applied to the substrate surface. Excess photosensitive solution is discharged from the discharge unit 267.

  The circular slide hopper type coating apparatus causes the coating liquid to flow down along the slide surface 265, and the coating liquid reaching the end of the slide surface 265 is beaded between the end of the slide surface 265 and the cylindrical base 251A. After forming, a coating film is formed on a cylindrical base material.

  In the coating method using a circular slide hopper type coating apparatus, the slide surface end and the base material are arranged with a certain gap (about 2 μm to 2 mm), so that the base material is not damaged, and layers having different properties are multilayered. Even in the case of forming, it can be applied without damaging the already applied layer. Furthermore, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter compared to the dip coating method, so that the lower layer component hardly elutes to the upper layer side, and the coating tank Can be applied without degrading the dispersibility of the fluororesin fine particles.

  The fluorine-containing resin fine particles of the present invention have an average primary particle size of 0.02 μm or more and less than 0.20 μm. However, if the average primary particle size is less than 0.02 μm, the stability of the dispersion deteriorates, and the fluorine-containing resin fine particles Aggregation occurs, it is difficult to uniformly disperse, contact angle variation is likely to increase, and the dash marks and image blur are likely to occur. On the other hand, if the average primary particle size is larger than 0.20 μm, agglomerated particles are likely to be formed due to sedimentation, and the contact angle of the surface is increased. Scatters exposure and degrades sharpness. The average primary particle size of the fluororesin fine particles is more preferably 0.02 μm or more and 0.18 μm or less.

In this specification, the average primary particle diameter is a value measured by DLS-6000 (manufactured by Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. However, it does not have to be measured by the above apparatus, and may be measured by any apparatus as long as it can be measured by the same principle as that of the above apparatus or by laser diffraction method and centrifugal sedimentation method. If the same measurement as in the above apparatus is possible, it may be measured by observing the cross section of the photosensitive layer. If the contact angle of the surface layer with respect to water is less than 90 °, an inorganic external additive such as silica in the toner is used. Adhesion increases and dash marks are likely to occur. In addition, the frictional resistance with the contact member of the photosensitive member such as a cleaning blade is large, wear due to scratching is increased, streaky image unevenness is generated, and the sharpness of the halftone image is easily deteriorated. A more preferable contact angle is 95 ° or more and 120 ° or less. If the contact angle is made larger than 120 °, the content of the fluororesin fine particles in the surface layer becomes too high, the surface layer becomes soft, and scratches are easily generated, and image blur is likely to occur. Further, when the contact angle variation of the surface layer is larger than ± 2.0 °, the dispersibility of the fluororesin fine particles in the surface layer is not uniform, and scattering of image exposure such as short wavelength laser light increases. At the same time, inorganic components in the toner or in the paper powder, for example, inorganic external additives such as silica and titanium oxide in the toner, talc component in the paper powder, and the like are embedded in the surface layer, and a dash mark is likely to be generated. Also, black stripes and white stripes are likely to occur, and the halftone image tends to deteriorate. The variation in contact angle is more preferably ± 1.7 °.

Measurement of Contact Angle and Contact Angle Variation The contact angle of the present invention refers to the contact angle of pure water on the surface of the photoreceptor. The contact angle of the photoreceptor is measured with a contact angle meter (CA-DT • A type: manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 20 ° C. and 50% RH.

  The contact angle variation is measured in an environment of 20 ° C. and 50% RH. The measurement is performed when the photoreceptor is sufficiently familiar with image formation (after forming at least several printed images). When the photoconductor is cylindrical, measure the four locations at 90 ° in the circumferential direction at three locations, 5 cm from the center and the left and right ends, for a total of 12 locations. The contact angle according to the present invention was used, and the value that was the largest or most negative from this average value was determined as the variation value. In the case where the photosensitive member is a sheet, similarly, at the three positions of 5 cm from the central portion and the left and right end portions, four locations are measured at equal intervals, and a total of 12 locations are measured. The contact angle was defined as the variation value, which was the largest deviation from the average value in the positive or negative direction.

  The fluororesin fine particles of the present invention preferably have a crystallinity of 40% or more and less than 90%. When the crystallinity is 90% or more, the dispersibility of the fluorine-containing resin fine particles is improved, but the spreadability of the fluorine-containing resin fine particles itself is reduced, and the variation in the contact angle tends to increase. Further, if the degree of crystallinity of the fluororesin fine particles becomes too small, the spreadability becomes excessive and the dispersibility tends to deteriorate. Therefore, the fluororesin fine particles having a crystallinity of 40% or more are preferable.

  The crystallinity of the fluororesin fine particles is measured by wide-angle X-ray diffraction measurement. The generated diffraction peak is separated into crystalline and amorphous, and after correcting the baseline, the crystalline and amorphous total X It is expressed as a percentage (%) of the X-ray integral intensity (numerator) of the crystalline with respect to the line integral intensity (denominator).

  In the present invention, the wide-angle X-ray diffraction measurement device and the measurement conditions were measured as follows, but other measurement devices and the like may be used as long as the same result is obtained.

X-ray generator: Rigaku RU-200B
Output: 50kV, 150mA
Monochromator: Graphite Radiation source: CuKα (0.154184 nm)
Scanning range: 3 ° ≦ 2θ ≦ 60 °
Scanning method: θ-2θ
Scanning speed: 2 ° / min
The constituent material of the fluorine-containing resin fine particles is a homopolymer or copolymer of a fluorine-containing polymerizable monomer, or a copolymer of a fluorine-containing polymerizable monomer and a fluorine-free polymerizable monomer. The fluorine-containing polymerizable monomer has a general formula;

(In the formula, at least one group of R ^{4 to} R ⁷ is a fluorine atom, and the remaining groups are each independently a hydrogen atom, a chlorine atom, a methyl group, a monofluoromethyl group, a difluoromethyl group, or trifluoro). Is a methyl group). Preferable fluorine-containing polymerizable monomers include ethylene tetrafluoride, ethylene trifluoride, ethylene trifluoride chloride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, ethylene difluoride dichloride and the like. Two or more types of monomers may be used as the fluorine-containing polymerizable monomer.

  Examples of the fluorine-free polymerizable monomer include vinyl chloride. Two or more types of monomers may be used as the fluorine-free polymerizable monomer.

  All of the fluororesin fine particles are preferably made of a homopolymer or copolymer of a fluoropolymerizable monomer among the above-mentioned constituent materials, more preferably polytetrafluoroethylene (PTFE) or polytrifluoride. Ethylene, ethylene tetrafluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, especially polytetrafluoroethylene.

  The average molecular weight of the polymer constituting the fluorine-containing resin fine particles is not particularly limited as long as the object of the present invention can be achieved, but usually the range of 10,000 to 1,000,000 is preferable.

  The crystallinity of the fluororesin fine particles of the present invention varies depending on the constituent material of the fluororesin fine particles, but can also be changed by heat-treating the fluororesin fine particles. For example, when PTFE fine particles (polyethylene terephthalate fine particles) having an average primary particle size of 0.12 μm and a crystallinity of 91.3 are heat-treated at 250 ° C. for 65 minutes, the crystallinity can be reduced to 82.8. The heat treatment means is not particularly limited, and a known dryer or heating furnace can be used.

  As the binder resin in the surface layer, it is preferable to use a resin having a surface active group that assists the dispersibility of the fluorine-containing resin fine particles in the resin partial structure. For example, a polycarbonate or polyarylate having a siloxane group in the partial structure is used. preferable. In particular, a siloxane-modified polycarbonate having a siloxane group shown below in a partial structure is preferable.

  The molecular weight is preferably 10,000 to 100,000.

  In order to form a surface layer having a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 ° using the fluorine-containing resin fine particles of the present invention, the fluorine-containing resin in the surface layer is used. It is preferable to increase the ratio of the fine particles, and it is preferable to use at least 20 parts by mass and 200 parts by mass with respect to 100 parts by mass of the binder resin. If it is less than 20 parts by mass, it is difficult to form a surface layer that satisfies the contact angle of 90 ° or more and the contact angle variation of ± 2.0 ° at the same time, and if it exceeds 200 parts by mass, the surface layer becomes a fragile film. Scratches are likely to occur.

  The present invention is an organic photoreceptor having a surface layer as described above. The constitution of the organic photoreceptor other than the surface layer will be described below.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoconductor. All known organic photoconductors such as a photoconductor composed of an organic charge generating material or an organic charge transport material, a photoconductor composed of a polymer complex with a charge generating function and a charge transport function are contained.

The structure of the photoconductor of the present invention is that the photoconductor contains fluororesin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm, the contact angle with water is 90 ° or more, and the contact angle varies. Is not particularly limited as long as it has a surface layer of ± 2.0 °, and examples thereof include the following configurations;
1) A structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support. 2) A charge generation layer, a first charge transport layer and a second charge transport layer are formed as a photosensitive layer on a conductive support. Sequentially stacked configuration;
3) A structure in which a single layer containing a charge transport material and a charge generation material is formed as a photosensitive layer on a conductive support;
4) A structure in which a charge transport layer and a charge generation layer are sequentially laminated as a photosensitive layer on a conductive support;
5) A structure in which a surface protective layer is further formed on the photosensitive layer of the photoreceptors 1) to 5) above.

  The photoconductor may have any of the above configurations. The surface layer of the photoreceptor is a layer in contact with the air interface. When only a single-layer photosensitive layer is formed on the conductive support, the photosensitive layer is the surface layer, and the conductive layer In the case where a single-layered or laminated photosensitive layer and a surface protective layer are laminated on the conductive support, the surface protective layer is the outermost surface layer. In the present invention, the configuration 2) is most preferably used. Note that, regardless of the structure of the photoreceptor of the present invention, an undercoat layer may be formed on the conductive support prior to the formation of the photosensitive layer.

  The charge transport layer of the present invention means a layer having a function of transporting charge carriers generated in the charge generation layer by light exposure to the surface of the organic photoreceptor, and the specific detection of the charge transport function is charge generation. It can be confirmed by laminating a layer and a charge transport layer on a conductive support and detecting the optical conductivity.

  A specific configuration of the photoreceptor will be described below by taking as an example the layer configuration of 2) which is most preferably used in the present invention.

Conductive Support As the conductive support used in the photoreceptor of the present invention, a sheet-like or cylindrical conductive support is used.

  The cylindrical conductive support of the present invention means a cylindrical support necessary for forming an endless image by rotating, and the cylindricity is preferably 5 to 40 μm, more preferably 7 to 30 μm.

  This cylindricity is based on JIS standard (B0621-1984). That is, when the cylindrical substrate is sandwiched between two coaxial geometric cylinders, it is represented by the difference in radius at the position where the distance between the two coaxial cylinders is minimum. In the present invention, the difference in radius is represented by μm. The method of measuring the cylindricity is obtained by measuring the roundness of 7 points in total, that is, 2 points 10 mm on both ends of the cylindrical substrate, 4 points of the central part, and 4 points obtained by dividing the distance between the both ends. The measuring device can be measured using a non-contact universal roll diameter measuring machine (manufactured by Mitutoyo Corporation).

As a material for the conductive support, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide, or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

Intermediate layer In the present invention, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.

  In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.

  Examples of the intermediate layer preferably used in the present invention include an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.

  An intermediate layer preferably used in the present invention includes an intermediate layer in which inorganic particles are dispersed in a binder resin. The average particle diameter of the inorganic particles is preferably 0.01 to 1 μm. In particular, an intermediate layer in which N-type semiconductive fine particles subjected to surface treatment are dispersed in a binder is preferable. For example, an intermediate layer in which titanium oxide having an average particle size of 0.01 to 1 μm, which has been surface-treated with silica / alumina treatment and a silane compound, is dispersed in a polyamide resin. The film thickness of such an intermediate layer is preferably 1 to 20 μm.

  The N-type semiconducting fine particles are fine particles having the property of using conductive carriers as electrons. That is, the property that the conductive carrier is an electron is that the N-type semiconducting fine particles are contained in an insulating binder to effectively block hole injection from the substrate, and to convert electrons from the photosensitive layer into electrons. On the other hand, it has the property which does not show blocking property.

  Here, a method for discriminating N-type semiconductor particles will be described.

  An intermediate layer having a thickness of 5 μm is formed on the conductive support (the intermediate layer is formed using a dispersion in which 50% by mass of particles are dispersed in the binder resin constituting the intermediate layer). The intermediate layer is negatively charged and the light attenuation characteristics are evaluated. In addition, the light attenuation characteristics are similarly evaluated by charging to positive polarity.

  N-type semiconductive particles are particles that are dispersed in the intermediate layer in the above evaluation when the light attenuation when charged negatively is greater than the light attenuation when charged positively. It is called semiconductive particle.

Specific examples of the N-type semiconducting fine particles include fine particles of titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), etc. In the present invention, titanium oxide is particularly preferably used. It is done.

  The average particle diameter of the N-type semiconducting fine particles used in the present invention is preferably in the range of 10 nm to 500 nm in the number average primary particle diameter, more preferably 10 nm to 200 nm, and particularly preferably 15 nm to 50 nm. .

  The intermediate layer using N-type semiconducting fine particles whose number average primary particle size is within the above range can be finely dispersed in the layer, has sufficient potential stability, and generates black spots. Has a prevention function.

  For example, in the case of titanium oxide, the number-average primary particle size of the N-type semiconducting fine particles is magnified 10,000 times by observation with a transmission electron microscope, and 100 particles are randomly observed as primary particles. It is measured as the number average diameter.

  The shape of the N-type semiconducting fine particles used in the present invention includes dendritic, needle-like, and granular shapes. For example, in the case of titanium oxide particles, the N-type semiconductive fine particles have a crystalline form. There are anatase type, rutile type and amorphous type, but any crystal type may be used, or two or more crystal types may be mixed and used. Of these, the rutile type is the best.

  One of the hydrophobizing surface treatments performed on the N-type semiconducting fine particles is a plurality of surface treatments, and the last surface treatment is a surface treatment with a reactive organosilicon compound. Is to do. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally the surface treatment of the reactive organosilicon compound is performed. It is preferable.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for depositing alumina, silica, or zirconia on the surface of the N-type semiconducting fine particles. Alumina, silica, and zirconia deposited on these surfaces include alumina, silica, Zirconia hydrates are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, the surface treatment of the N-type semiconductive fine particles such as titanium oxide particles was performed at least twice, so that the surface of the N-type semiconductive fine particles was uniformly coated (treated), and the surface treatment was performed. When N-type semiconducting fine particles are used in the intermediate layer, a good photoconductor having good dispersibility of N-type semiconductive fine particles such as titanium oxide particles in the intermediate layer and causing no image defects such as black spots. You can get it.

Photosensitive layer Charge generating layer In the organic photoreceptor of the present invention, it is preferable to use a charge generating material having high sensitivity characteristics in the wavelength region of 350 nm to 500 nm as the charge generating material. As such a charge generating substance, an azo pigment, a perylene pigment, a multisensitive quinone pigment, or the like is preferably used. These pigments can be used in combination. Examples of pigment compounds preferably used in the present invention are shown below.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.3 μm to 2 μm.

Charge Transport Layer As described above, in the present invention, the charge transport layer is preferably composed of a plurality of charge transport layers, and the uppermost charge transport layer contains fluorine-based resin particles.

  The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. As other substances, additives such as an antioxidant may be contained in addition to the above-described fluororesin particles as necessary.

  As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer. In particular, a charge transport material that does not absorb the wavelength of laser light for image exposure is preferably used. Examples of the charge transport material preferably used in the present invention include the following compounds.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The total thickness of the charge transport layer is preferably 20 μm or less, and more preferably 10 to 16 μm. When the film thickness exceeds 20 μm, the absorption and scattering of the short wavelength laser in the charge transport layer increase, and the sharpness tends to decrease and the residual potential tends to increase.

  The surface layer containing the fluororesin fine particles of the present invention preferably contains an antioxidant. The surface layer containing the fluorine-containing resin fine particles is easily oxidized by an active gas such as NOx or ozone during charging of the photoconductor, and image blurring is likely to occur. However, the presence of an antioxidant causes image blurring. Can be prevented. Typical examples of the antioxidants are those that prevent the action of oxygen under conditions of light, heat, discharge, etc. on auto-oxidizing substances present in the organic photoreceptor or on the surface of the organic photoreceptor, It is a substance that has the property of inhibiting. Typical examples include the following compound groups.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  Next, an image forming apparatus using the organic photoreceptor of the present invention will be described.

  FIG. 3 is a schematic sectional view of the image forming apparatus 1 using the cleaner-less process according to the present invention. The image forming apparatus 1 includes a photosensitive cartridge 2, a developing cartridge 3, an exposure device 4 that emits a laser beam modulated based on an image signal from the outside while deflecting, a paper feeding device 5 that supplies recording paper, A transfer roller 6, a fixing device 7 and a paper discharge tray 8 are provided.

  The photoconductor cartridge 2 includes a photoconductor 21 formed by forming a thin film layer of an organic photoconductive material on the outer peripheral surface of a cylindrical body, a charging brush 22 and the like. The developing cartridge 3 includes a developing sleeve (not shown), a stirring roller, and a toner tank in which toner and a carrier are accommodated. A developing bias is applied to the developing sleeve from a developing power source (not shown). Both cartridges are closed when inserted into the image forming apparatus 1 in order to prevent problems caused by mechanical contact when the cartridge is attached to or detached from the image forming apparatus 1, and are removed from the image forming apparatus 1. A protective cover (not shown) that is sometimes opened is provided.

  Since the image forming process is well known, only a brief description will be given below. First, the surface of the photoreceptor 21 is uniformly charged with a predetermined voltage by the charging brush 22. The exposure device 4 generates a modulated laser beam (indicated by a broken arrow in the figure), deflects the laser beam by a polygon mirror (not shown), deflects and scans the surface of the photosensitive member 21, and applies it to the charged surface. The electrostatic latent images corresponding to the image information are sequentially formed.

  The image forming apparatus of the present invention is premised on the use of a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm as an image exposure light source when forming an electrostatic latent image on a photoreceptor. By using these image exposure light sources, the spot diameter of the image exposure (the spot diameter of the exposure beam) is reduced to 60 nm or less, preferably 60 nm or less, and 15 nm or more, and digital exposure is performed on the organic photoreceptor, A high-resolution electrophotographic image of 2400 dpi can be obtained from 600 dpi (dpi: the number of dots per 2.54 cm) or more.

The spot diameter of the exposure beam is defined as a diameter of the perfect circle area by converting an area corresponding to a light intensity at which the intensity of the exposure beam is 1 / e ² or more of the peak intensity into a perfect circle area.

  The toner in the toner tank is stirred by a stirring roller and then supplied onto the developing sleeve to form a toner image corresponding to the electrostatic latent image at a portion facing the photoreceptor 21. At the same time, residual toner existing in a portion (non-image portion) that has not been exposed on the surface of the photoconductor 21 is developed using the potential difference between the developing bias voltage applied to the developing sleeve and the surface potential of the photoconductor 21. Collected in cartridge. On the other hand, the toner image is electrostatically transferred onto the recording paper by the transfer roller 6 disposed facing the photoconductor 21. Note that the recording paper is conveyed from the paper feeding device 5 along a conveyance path indicated by a solid line arrow in the drawing. Next, the recording paper is conveyed to the fixing device 7 where the unfixed toner image is heat-fixed on the recording paper. Finally, the recording paper on which a desired image is formed is discharged from the paper discharge tray 8. By repeating the above-described series of processes, a large amount of original can be duplicated at high speed.

  The charging brush mechanically agitates the residual toner sent to the contact portion with the photoconductor by the rotation of the photoconductor and diffuses it on the surface of the photoconductor until it becomes unreadable. The charging brush electrostatically adsorbs and collects residual toner having the opposite polarity (reverse polarity) to the charging polarity of the photoconductor, and charges it to the same polarity (regular polarity) as the charging polarity of the photoconductor. Discharge onto the surface of the photoreceptor.

  FIG. 4 is a schematic cross-sectional view of the photoreceptor cartridge 2 that is detachable from the image forming apparatus 1. The photosensitive member cartridge 2 includes a protective member 28 with a protective cover, a photosensitive member 21 as an image carrier, a charging brush 22 disposed around the photosensitive member 21, and a power source for applying a predetermined voltage to the charging brush 22. The connecting member 23, the pre-charge film 24, the charge leveling members (sponge-like charging members) 25 and 26, and the power source connecting member 27 are accommodated.

  The photosensitive member 21 is rotated in the direction of the arrow in the drawing by a driving device (not shown). The charging brush 22 is obtained by implanting conductive yarn made of hairy fibers on a brush support. The charging brush 22 is in contact with the surface of the photosensitive member 21 and is rotated in the same direction as the rotational direction of the photosensitive member 21 in the direction of the arrow in the drawing, that is, in the contact portion with the photosensitive member 21 by a driving device (not shown). . At the time of image formation, a voltage is applied to the charging brush 22 from a charging power source (not shown), whereby the surface of the photoreceptor 21 is uniformly charged to a predetermined polarity. On the other hand, at the time of non-image formation, a voltage having a polarity opposite to that at the time of image formation is applied to the charging brush 22 from the charging power source. The charging polarity of the toner is the same as the polarity of the charging voltage at the time of image formation. Therefore, at the time of non-image formation, the toner accumulated in the charging brush 22 can be ejected onto the photoreceptor 21 by electrostatic repulsion.

  The development pre-charge film 24 and the charge leveling members 25 and 26 are disposed for the purpose of compensating uneven charging due to the charging brush 22.

  In the image forming apparatus of the present invention, it is preferable to use a polymerized toner as a developer used in the developing unit. By using a polymerized toner having a uniform shape and particle size distribution in combination with the organic photoreceptor of the present invention, an electrophotographic image with better sharpness can be obtained.

  Here, the polymerized toner means a toner obtained by forming a resin for a toner binder and forming the toner shape by polymerization of a raw material monomer of the binder resin and subsequent chemical treatment. More specifically, it means a toner obtained through a polymerization reaction such as suspension polymerization or emulsion polymerization and, if necessary, a subsequent step of fusing particles.

  Since the polymerized toner is produced by uniformly dispersing the raw material monomers in an aqueous system and then producing the toner, a toner having a uniform toner particle size distribution and shape can be obtained.

  The polymerized toner is produced by emulsion polymerization of monomers in a suspension polymerization method or in a solution to which an emulsion of necessary additives is added to produce fine polymer particles, and then an organic solvent, an aggregating agent, etc. It can manufacture by the method of adding and associating. A method of preparing by mixing with a dispersion liquid such as a release agent or a colorant necessary for the composition of the toner at the time of association, or a toner component such as a release agent or a colorant is dispersed in the monomer And a method of emulsion polymerization. Here, the association means that a plurality of resin particles and colorant particles are fused.

  That is, various constituent materials such as a colorant and, if necessary, a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, etc. Various constituent materials are dissolved or dispersed in the polymerizable monomer. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in oil droplets having a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. Thereafter, the stirring mechanism is transferred to a reaction apparatus which is a stirring blade described later, and the polymerization reaction is advanced by heating. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare a toner.

  Further, as a method for producing the toner of the present invention, a method of preparing by associating or fusing resin particles in an aqueous medium can also be mentioned. The method is not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904. That is, a method of associating a plurality of fine particles composed of resin particles and colorants, etc., or particles composed of resin and colorant, in particular, after dispersing them in water using an emulsifier, the critical aggregation concentration The above flocculant is added for salting out, and at the same time, the formed polymer itself is heated and fused at a temperature higher than the glass transition temperature to gradually grow the particle size while forming fused particles. Then, a large amount of water is added to stop the particle size growth, and the shape is controlled by smoothing the particle surface while heating and stirring, and the particles are heated and dried in a fluidized state while containing water, whereby toner Can be formed. Here, an organic solvent that is infinitely soluble in water may be added simultaneously with the flocculant.

  Note that materials and manufacturing methods for producing a uniform toner such as a shape factor used in the present invention, a polymerization toner reaction device, and the like are described in detail in JP-A-2000-214629.

  A charging roller may be used in place of the charging brush shown in FIGS. FIG. 5 is a cross-sectional view showing the configuration of the charging roller.

  As shown in FIG. 5, the charging roller 22R comprises a cored bar 22a and a rubber layer such as chloroprene rubber, urethane rubber, silicone rubber or the like, which is a conductive elastic member provided on the outer periphery thereof, or a sponge layer 22b thereof. Preferably, the outermost layer is configured by providing a protective layer 22c made of a releasable fluorine-based resin or silicone resin layer having a thickness of 0.01 to 1 μm.

  The charging roller is preferably brought into contact with the photoreceptor 21 with a pressure contact force of 10 to 100 g / cm. The rotation of the charging roller is preferably 1 to 8 times the peripheral speed of the photosensitive drum 21.

  Although the image forming apparatus is a contact charging type monochrome laser printer, the same effect can be obtained by using a non-contact type laser printer as a charging unit. The present invention can be similarly applied to a color laser printer and a copy. The exposure light source may also be a light source other than a laser, such as an LED light source.

  Further, a magnetic brush charger may be used in place of the charging brush shown in FIGS. FIG. 6 is a diagram illustrating an example of a cross section of the magnetic brush charger.

In FIG. 6, 120 is a magnetic brush charger, 21 is a photosensitive drum, T charging unit, 120a is a charging sleeve, 121 is a magnet body 121, 123 is a scraper, and 124 is a stirring screw. The magnetic brush charger 120 is opposed to the rotating photosensitive drum 21 and serves as a magnetic particle carrier for charging that rotates in the same direction (counterclockwise) at a portion close to the photosensitive drum 21 (charging portion T). For example, a cylindrical charging sleeve 120a using an aluminum material or a stainless material, a magnet body 121 having N and S poles provided inside the charging sleeve 120a, and the magnet body 121 on the outer peripheral surface of the charging sleeve 120a. A magnetic brush composed of magnetic particles formed to charge the photosensitive drum 21 and the charging sleeve 120a at the NN magnetic pole portion of the magnet body 121. A scraper 123 that scrapes the upper magnetic brush, and a stirring screw 124 that stirs the magnetic particles in the magnetic brush charger 120 or causes the used magnetic particles to overflow from the outlet 125 of the magnetic brush charger 120 and discharge the magnetic particles when supplying the magnetic particles. And a brushing restriction plate 126 of the magnetic brush. The charging sleeve 120 a is rotatable with respect to the magnet body 121, and is 0.1 to 1.0 times in the same direction (counterclockwise) as the movement direction of the photosensitive drum 21 at a position facing the photosensitive drum 21. It is preferably rotated at a peripheral speed. As the charging sleeve 120a, a conductive carrier capable of applying a charging bias voltage is used. In particular, the magnet body 121 having a plurality of magnetic poles inside the conductive charging sleeve 120a having a particle layer formed on the surface thereof. Those having a structure provided with are preferably used. In such a carrier, the magnetic particle layer formed on the surface of the conductive charging sleeve 120a moves up and down in a wave shape due to the relative rotation with the magnet body 121. Even if the magnetic particle layer on the surface of the charging sleeve 120a is somewhat uneven in thickness, the influence is sufficiently covered so as not to cause a problem due to the wavy undulations. The surface of the charging sleeve 120a preferably has an average surface roughness of 5.0 to 30 [mu] m for stable and uniform transfer of magnetic particles. If the surface is smooth, the surface cannot be sufficiently transported. Overcurrent flows from the part, and in any case, uneven charging tends to occur. Sand blasting is preferably used to achieve the above surface roughness. Further, the outer diameter of the charging sleeve 120a is preferably 5.0 to 20 mm. This ensures a contact area necessary for charging. If the contact area is larger than necessary, the charging current becomes excessive, and if it is small, charging unevenness is likely to occur. Further, when the diameter is small as described above, magnetic particles are likely to be scattered or adhere to the photosensitive drum 21 due to centrifugal force, so that the linear velocity of the charging sleeve 120a is almost the same as the moving velocity of the photosensitive drum 21 or more. It is also preferable that it is slow.

Further, the thickness of the magnetic particle layer formed on the charging sleeve 120a is preferably a thickness that is sufficiently scraped off by the regulating means to form a uniform layer. If there is too much magnetic particles on the surface of the charging sleeve 120a in the charging region, the magnetic particles will not vibrate sufficiently, causing photoconductor wear and charging unevenness and overcurrent easily flowing, and driving torque of the charging sleeve 120a. Has the disadvantage of becoming larger. On the other hand, if the amount of the magnetic particles on the charging sleeve 120a in the charged region is too small, an incomplete portion is formed in contact with the photosensitive drum 21 and the magnetic particles adhere to the photosensitive drum 21 and uneven charging occurs. become. Result of repeated experimentation, the preferred deposition amount of the magnetic particles in the charging area is 100 to 400 mg / cm ^2, particularly preferably has proven 200-300 mg / cm ^2. This adhesion amount is an average value in the charging region of the magnetic brush.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

The surface of the cylindrical aluminum support was cut to prepare a conductive support having a ten-point surface roughness Rz = 1.5 (μm).
<Intermediate layer>
The following intermediate layer dispersion was diluted twice with the same mixed solvent, and allowed to stand overnight, followed by filtration (filter; rigesh mesh 5 μm filter manufactured by Nihon Pall) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Inorganic particles: Titanium oxide (Number average primary particle size 35 nm: Titanium oxide treated with silica / alumina and methylhydrogenpolysiloxane) 3 parts Methanol 10 parts are mixed as a disperser Using a sand mill, batch dispersion was performed for 10 hours to prepare an intermediate layer dispersion.

  It apply | coated so that it might become a dry film thickness of 1.0 micrometer on the said support body using the said coating liquid.

<Charge generation layer: CGL>
Charge generation material (CGM): 24 parts of the above-mentioned CGM-1 Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts The mixture was mixed and dispersed using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

<Charge transport layer 1 (CTL1)>
Charge transport material (CTM-4) 225 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical) 300 parts Antioxidant (Irganox 1010: manufactured by Ciba Geigy Japan) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) ) 1 part was mixed and dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 10.0 μm.

<Preparation of polytetrafluoroethylene resin particle (PTFE particle) dispersion>
PTFE particles (PTFE particles having an average primary particle size of 0.12 μm and a crystallinity of 91.3) were heat-treated at 250 ° C. for 40 minutes, and PTFE particles having a crystallinity of 82.8 were used. A liquid was prepared.

PTFE particles (PT1: average primary particle size 0.12 μm, crystallinity 82.8) 200 parts Toluene 600 parts Fluorine comb type graft polymer (trade name GF300, manufactured by Toagosei Co., Ltd.) 15 parts were mixed. After that, a PTFE particle dispersion was prepared by dispersing with a sand grinder (made by Amex Co., Ltd.) using glass beads.

<Charge transport layer 2 (CTL2)>
PTFE particle dispersion 815 parts Charge transport material (CTM-4) 150 parts Siloxane-modified polycarbonate resin (PC-1) 150 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 150 parts Antioxidant (Exemplary Compound 2-1) 12 parts THF: tetrahydrofuran 2800 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts were mixed and dissolved to prepare a charge transport layer coating solution 2. This coating solution is applied onto the charge transport layer 1 with a circular slide hopper coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 having a dry film thickness of 2.0 μm, and the photoreceptor 1 is formed. Produced.

Production of photoconductors 2 to 12 In production of photoconductor 1, except that the thickness of charge transport layer 1, the type and addition amount of fluororesin particles of charge transport layer 2 (CTL 2) were changed as shown in Table 1. Photoconductors 2 to 12 were produced in the same manner as the photoconductor 1.

In Table 1,
PTFE and H represent the following fluororesin fine particles.

PTFE: Polyethylene terephthalate resin particles H: Copolymer resin particles of ethylene trifluoride-tetrafluoroethylene Further, the contact angles and contact angle variations in Table 1 are measured by the above-described method, and the contact angle variations are absolute values. Displayed.

<< Evaluation 1 >>
The obtained photoreceptor is basically mounted on an EPSONLP-2400 (Epson Co., Ltd .: printer: 16 sheets / minute A4 paper: cleaner-less process) having the structure shown in FIGS. The short wavelength laser light source shown below was used as the light source, and sharpness evaluation and the like were performed. Specifically, from the start up to 10,000 sheets, character images and halftone images were printed and evaluated. Evaluation items and evaluation criteria are shown below.

  The printer process conditions were as follows.

Charger: Charging brush Exposure unit: Semiconductor laser (oscillation wavelength: 405 nm)
Development: Nonmagnetic toner (polymerized toner) having an average particle diameter of 4.5 μm, toner containing an external additive of 0.3 μm strontium titanate and 15 nm hydrophobic silica, reversal development method (sharpness)
The spot diameter of the laser beam was changed, and halftone images of 600 dpi (spot diameter of 50 nm), 1200 dpi (spot diameter of 30 nm), and 2400 dpi (spot diameter of 15 nm) were prepared and evaluated.

  Rank A: From 600 dpi to 2400 dpi, halftone images of each dpi are reproduced clearly (each dot is independent) (high image quality characteristics are very good).

  Rank B: Each dpi halftone image is clearly reproduced from 600 dpi to 1200 dpi, but the 2400 dpi halftone image has insufficient clarity (independence of each dot) (good image quality characteristics are good).

  Rank C: 600 dpi halftone images are clearly reproduced, but 1200 and 2400 dpi halftone images are insufficiently clear (having high image quality characteristics).

Rank D: Insufficient clarity (independence of each dot) even with a halftone image of 600 dpi (insufficient image quality)
(Image blur)
◎ No blurring of image through printing 10,000 sheets (good)
○: Several images (less than 10) were generated through printing 10,000 sheets, but there was no practical problem (no problem in practical use)
×: During printing of 10,000 sheets, 10 or more partial image blurs or 1 or more image blurs in a wide range occurred (practical problem)
Dash Mark The occurrence of a dash mark (small comet-like streak image) on a halftone image was determined according to the following criteria.

◎: Dash mark nuclei are not seen on the photoconductor, and no dash marks are generated on halftone images (good)
○: Dash mark nuclei are seen on the photoreceptor, but no dash marks are generated in the halftone image (no problem in practical use)
×: Dash mark nuclei are seen on the photoconductor, and dash marks are also generated in halftone images (practical problems)

  From Table 2, a surface layer (= charge transport layer 2) having an average primary particle size of 0.02 μm or more and less than 0.20 μm, a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 ° Organic photoreceptors 1 to 3, 6 to 8, and 10 to 12 have a sharpness of rank C or higher, and image blurring, dash marks, and sharpness are improved. On the other hand, the photoconductor 4 using PTFE-4 having an average primary particle size of 0.01 μm is inferior in dispersibility of the fluorine-containing resin fine particles in the surface layer and has a large contact angle variation of 2.2. Blur is generated, and the sharpness is degraded to rank D. Further, the photoreceptor 5 using PTFE-5 having an average primary particle size of 0.22 μm also has a large contact angle variation of 2.3 on the surface layer, resulting in dash marks and image blurring, and scattering of laser exposure. Increased, sharpness has also deteriorated. Further, the photoconductor 9 in which the content of PTEF-1 is reduced in the surface layer (= charge transport layer 2) and the contact angle is lowered to 88 shows generation of a dash mark, and the sharpness is ranked D. It has deteriorated.

<< Evaluation 2 >>
Evaluation was performed in the same manner as in Evaluation 1 except that the semiconductor laser of the exposure device was changed to a light emitting diode (oscillation wavelength: 430 nm) under the evaluation conditions in Evaluation 1. Even when the light emitting diode was used as the image exposure light source, the evaluation result was almost the same as in Evaluation 1.

Production of photoconductors 13 to 16 In production of photoconductor 1, the charge generation material of the charge generation layer was changed from CGM-1 to CGM-2, CGM-3, CGM-4, and CGM-1 as shown in Table 3. The charge transport materials of the charge transport layer 1 and the charge transport layer 2 are the same as described in Table 3, except that the charge transport materials are changed to CTM-1, CTM-2, CTM-3, CTM-5 as shown in Table 3. 13-16 were produced.

<< Evaluation 3 >>
The photoconductors 13 to 16 were evaluated in the same manner as in Evaluation 1 except that the oscillation wavelength of the semiconductor laser of the exposure device was changed to (oscillation wavelength: 480 nm) under the evaluation conditions in Evaluation 1. The evaluation results of the photoreceptors 13 to 16 are shown in Table 4.

  From Table 4, each of the photoconductors 13 to 16 has a sharpness of rank B or higher, and image blur, dash mark, and sharpness are improved.

Production of Photoreceptor 17 In the production of Photoreceptor 1, the following conductive layer and intermediate layer were used instead of the intermediate layer of Photoreceptor 1, and the following charge injection layer was used instead of charge transport layer 2. A photoconductor 17 was produced in the same manner as the photoconductor 1.

Conductive layer Conductive pigment: Tin oxide / antimony oxide-coated titanium oxide 10 parts Resistance adjusting pigment: Titanium oxide 10 parts Binder resin: Phenolic resin (Dainippon Ink & Chemicals, Pliofen J-325) 10 Part Leveling agent: Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., SH28PA) 0.001 part Solvent: Methanol / methoxypropanol = 1/1 20 parts A coating solution obtained by mixing and dispersing the above components on a conductive support by dip coating And a conductive layer having a thickness of 15 μm was formed by heating at 140 ° C. for 30 minutes.

Intermediate layer Next, 10 parts of copolymerized polyamide resin (Amilan CM-8000, manufactured by Toray Industries, Inc.), 30 parts of methoxymethylated 6 nylon resin (Toresin EF-30T, manufactured by Teikoku Chemical Co., Ltd.) The coating solution dissolved in a mixed solvent of 400 parts of methanol and 200 parts of n-butanol was dip-coated and dried with hot air at 90 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.68 μm. Subsequently, the charge generation layer and the charge transport layer 1 of the photoreceptor 1 were applied on the intermediate layer in the same manner as the photoreceptor 1.

Charge injection layer The surface was treated with methyl hydrogen silicone oil (trade name KF99, manufactured by Shin-Etsu Silicone Co., Ltd.). Surface with 72 parts of antimony-doped tin oxide fine particles having an average particle size of 0.02 μm (trade name: T-1, manufactured by Mitsubishi Materials Corporation) and a fluorine-modified silane coupling agent (trade name: LS1090, manufactured by Shin-Etsu Silicone Co., Ltd.) Processed. 48 parts of antimony-doped tin oxide fine particles (same as above) having an average particle size of 0.02 μm, sand mill together with 43.2 parts of acrylic monomer (trade name TMP3A-3, manufactured by Osaka Organic Chemical Co., Ltd.) having the following chemical structure and 210 parts of ethanol For 90 hours.

  In this solution, 200 parts of the PTFE particle dispersion used in the charge transport layer 2 of the photoreceptor 1 was mixed and dispersed in a sand mill apparatus for another 2 hours. Further, 6.48 parts of 2,4-diethylthioxanthone as a photopolymerization initiator, 2.16 parts of 4,4'-bis (diethylamino) benzophenone was added as an initiation assistant and dissolved to prepare a charge injection layer coating solution.

The charge injection layer coating solution is applied onto the charge transport layer 1 with a circular slide hopper type coater, and irradiated with ultraviolet rays at a light intensity of 1.20 × 10 ⁻⁵ W / m ² for 30 seconds with a metal halide lamp. Photocuring was performed, followed by drying with hot air at 120 ° C. for 1 hour and 40 minutes to form a charge injection layer (surface layer) having a thickness of 6 μm. The contact angle of the photoreceptor 17 was 108 °, and the contact angle variation was 1.3.

<< Evaluation 4 >>
Under the evaluation conditions of Evaluation 1, the charger is changed from the charging brush shown in FIG. 6 to a magnetic brush, a DC bias of −600 V is applied to the magnetic brush, and an AC bias of Vpp = 650 v and Vf = 1000 Hz is superimposed. Thus, charge was injected into the photoconductor, a surface potential of −600 V was applied to the photoconductor surface voltage, and the same evaluation as that of the photoconductor 1 was performed.

  The evaluation results of the photoconductor 17 are shown in Table 5.

  From Table 5, the photoconductor 17 has a sharpness of rank B or higher in any photoconductor, and image blur, dash mark, and sharpness are improved.

It is sectional drawing of the example of the circular slide hopper type coating device concerning this invention. It is a perspective view of the example of a circular slide hopper type application device concerning the present invention. 1 is a schematic cross-sectional view of an image forming apparatus using a cleaner-less process according to the present invention. 2 is a schematic cross-sectional view of a photosensitive cartridge that is detachable from an image forming apparatus. FIG. It is sectional drawing which showed the structure of the charging roller. It is a figure which shows an example of the cross section of a magnetic brush charger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoconductor cartridge 3 Developer cartridge 4 Exposure apparatus 5 Paper feeder 6 Transfer roller 7 Fixing device 8 Paper discharge tray 21 Photoconductor 22 Charging brush 23, 27 Power supply connection member 24 Pre-charge film 25, 26 Charging Element

Claims (8)

A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. In the organic photoreceptor used in the image forming apparatus for repeatedly forming the electrophotographic image by circulating the organic photoreceptor after the transfer to the charging means without being attached to the cleaning means contacting the surface of the organic photoreceptor, the average primary particle size is 0. An organic photoreceptor having a surface layer containing fluororesin fine particles having a size of 0.02 μm or more and less than 0.20 μm. A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. In the organic photoreceptor used in the image forming apparatus for repeatedly forming the electrophotographic image by circulating the organic photoreceptor after the transfer to the charging means without being attached to the cleaning means contacting the surface of the organic photoreceptor, the average primary particle size is 0. An organic sensation characterized by containing a fluororesin fine particle of 0.02 μm or more and less than 0.20 μm, having a surface layer having a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 °. Light body. 3. The organic photoconductor according to claim 1, wherein the organic photoconductor is composed of a charge generation layer and a plurality of charge transport layers on a conductive support, and the uppermost charge transport layer is a surface layer. body. The organophotoreceptor according to any one of claims 1 to 3, wherein the degree of crystallinity of the fluororesin fine particles is 40% or more and less than 90%. The organophotoreceptor according to claim 1, wherein the surface layer contains a siloxane-modified polycarbonate. The organophotoreceptor according to claim 1, wherein the surface layer contains an antioxidant. A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. 7. A process cartridge for use in an image forming apparatus for circulating an organic photoreceptor after transfer to a charging means without being attached to a cleaning means that contacts the surface of the organic photoreceptor to repeatedly form an electrophotographic image. The organic photoreceptor according to any one of the above and at least one of a charging unit, a latent image forming unit, a developing unit, a transfer unit, and a charge eliminating unit are integrally supported and attached to the main body of the image forming apparatus. A process cartridge which is a freely mountable. A latent image that forms an electrostatic latent image on the organic photoreceptor by performing image exposure using an organic photoreceptor and a charging unit that charges the organic photoreceptor and a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm Forming means, developing means for visualizing the electrostatic latent image with toner and forming a toner image on the organic photoreceptor, and transfer means for transferring the toner image to a transfer material. In the image forming apparatus in which the transferred organic photoconductor is circulated to the charging unit without being attached to the cleaning unit that contacts the surface of the organic photoconductor to repeatedly form an electrophotographic image, the organic photoconductor has an average primary particle size. An image forming apparatus comprising a surface layer containing fluororesin fine particles of 0.02 μm or more and less than 0.20 μm.

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