JP2005338447A - Organophotoreceptor, and process cartridge and image forming apparatus using the organophotoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organophotoreceptor used in an image forming apparatus for forming a high-definition electrophotographic image with short-wavelength laser light; to solve problems on an organophotoreceptor having a surface layer containing fluorine-containing resin fine particles, and to provide an organophotoreceptor which prevents scattering of short-wavelength laser light by fluorine-containing resin fine particles, prevents occurrence of a dash mark, black streaks and white streaks, and can form an electrophotographic image with good sharpness; and to provide a process cartridge and an image forming apparatus using the organophotoreceptor. <P>SOLUTION: The organophotoreceptor used in the image forming apparatus in which an organophotoreceptor is irradiated using a semiconductor laser or a light-emitting diode having an oscillation wavelength of 350-500 nm as an image exposure light source has a surface layer containing fluorine-containing resin fine particles having an average primary particle diameter 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.

  In recent years, organic photoreceptors (hereinafter also simply referred to as photoreceptors) have been widely used as electrophotographic photoreceptors. Organic photoreceptors have advantages over other photoreceptors, such as easy development of materials suitable for various exposure light sources from visible light to infrared light, the ability to select materials that are free from environmental pollution, and low manufacturing costs. However, there are disadvantages such as low mechanical strength and easy adhesion of foreign matter, poor chemical durability, deterioration of electrostatic characteristics of a photoreceptor when many sheets are printed, and generation of scratches on the surface.

  That is, the organic photoconductor is a surface generated by a mechanical external force applied when a toner image formed on the photoconductor is transferred to a transfer material such as paper or when residual toner on the photoconductor is cleaned. Durability (abrasion resistance) against foreign matter adhesion and scratches is required.

  Therefore, conventionally, in order to improve the adhesion of foreign matter and abrasion resistance of the photoreceptor, a technique is known in which fluorine-containing resin fine particles such as polytetrafluoroethylene resin (PTFE) are contained in the outermost surface layer of the photoreceptor. In particular, as a means for effectively reducing the friction coefficient of the photoreceptor surface and improving the wear resistance, the fluorine-containing resin fine particles having a low crystallinity (the X-ray diffraction pattern peak half-width is 0.28 or more). A technique that uses the above has been reported (Patent Document 1).

  On the other hand, an image forming apparatus using an organic photoreceptor is required to have an image forming apparatus 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). However, when a short wavelength laser beam is used, an organic photoreceptor having fluororesin fine particles in the surface layer has a problem that the fluororesin fine particles in the surface layer increase the scattering of the short wavelength laser and deteriorate the sharpness. Has occurred.

  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 laser beam is scattered inside the organic photosensitive member, and independent dots of the laser beam are not formed on the organic photosensitive member, thereby improving the sharpness or resolution. Is not fully demonstrated.

In particular, for the purpose of improving the durability described above, the organic photoreceptor having fluororesin fine particles in the surface layer is likely to scatter laser light, and when using short wavelength laser light, the sharpness improving effect is sufficient. There was a problem of not being able to demonstrate. Further, when forming the surface layer of the fluororesin fine particles, the fluororesin fine particles have low dispersion stability in the coating dispersion, and the particles tend to aggregate to form coarse aggregated particles. In addition to increasing the scattering of laser light, it is difficult to form a surface layer with uniform characteristics, and dash marks (small comet-like streak images), black streaks and white streaks appear in electrophotographic images, and the image quality is significantly reduced. The problem that occurred.
JP-A-8-328287 JP 2000-250239 A

  An object of the present invention is to provide an organic photoreceptor for use in an image forming apparatus for forming a high-definition electrophotographic image using the above-described short wavelength laser beam, and a surface layer containing fluorine-containing resin fine particles. An electrophotographic image that solves the above-mentioned problems of the organic photoreceptor having the above, prevents the scattering of short-wavelength laser light by the fluorine-containing resin fine particles, prevents the generation of dash marks, black streaks and white streaks, and has excellent sharpness And an image forming apparatus using the organic photoreceptor.

As a result of repeated investigations on the above problems, we have prevented the scattering of short-wavelength laser light from organic photoreceptors having a surface layer containing fluororesin fine particles, and at the same time, the generation of dash marks, black stripes, and white stripes. In order to prevent this, it is effective to reduce the particle size of the fluororesin fine particles and improve the dispersibility of the fluororesin fine particles in the surface layer to form a surface layer with a uniform surface energy. The present invention has been completed. In particular, the present invention has been completed by finding that a surface layer having a uniform surface energy can be formed by improving the dispersibility of fluororesin fine particles having a low crystallinity and a reduced diameter. That is, the dispersibility of the fluorine-containing resin fine particles in the surface layer makes the dispersibility of the fluorine-containing resin fine particles uniform in the coating dispersion, and at the same time, the coating dispersion is prepared and aggregates are formed in the coating dispersion. It has been found that a surface layer having a uniform low surface energy can be formed by forming a surface layer by a coating method in which the coating dispersion is used up before generation occurs, and the present invention has been completed. That is, the present invention is achieved by having the following configuration.
(Claim 1)
In an organic photoreceptor used in an image forming apparatus that irradiates a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm on an organic photoreceptor as an image exposure light source, the average primary particle size is 0.02 μm or more and less than 0.20 μm An organic photoreceptor having a surface layer containing fluorine-containing resin fine particles.
(Claim 2)
In an organic photoreceptor used in an image forming apparatus that irradiates a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm on an organic photoreceptor as an image exposure light source, the average primary particle size is 0.02 μm or more and less than 0.20 μm An organic photoreceptor comprising a fluororesin fine particle, having a surface layer having a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 °.
(Claim 3)
3. The organic photoconductor according to claim 1, wherein the organic photoconductor comprises a charge generation layer and a plurality of charge transport layers on a conductive support, and the uppermost layer of the plurality of layers 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)
The organic photoreceptor according to any one of claims 1 to 6, a charging means for uniformly charging the organic photoreceptor, a latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, Developing means for developing an electrostatic latent image on the organic photoreceptor, transfer means for transferring a toner image visualized on the organic photoreceptor onto a transfer material, and on the organic photoreceptor after transfer At least one of a charge removing means for removing electric charges and a cleaning means for removing toner remaining on the organic photoreceptor after transfer is integrally supported, and can be detachably attached to the image forming apparatus main body. Process cartridge characterized by.
(Claim 8)
An image forming apparatus, wherein an electrophotographic image is formed using the organophotoreceptor according to claim 1.

  By using the organophotoreceptor of the present invention, the dispersibility of the fluororesin fine particles in the surface layer can be made uniform, dash marks, image unevenness and image blur, which have been problems in the past, can be improved, and sharpness is improved. Can form an excellent electrophotographic image. 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 an organic photoreceptor used in an image forming apparatus that irradiates a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm as an image exposure light source, and the organic photoreceptor has an average primary particle size. It has a surface layer containing fluororesin fine particles of 0.02 μm or more and less than 0.20 μm.

  The organic photoreceptor of the present invention is an organic photoreceptor used in an image forming apparatus that irradiates a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm as an image exposure light source. The organic photoreceptor has an average primary particle size. It contains fluorine-containing resin fine particles having a diameter of 0.02 μm or more and less than 0.20 μm, and has a surface layer having a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 °. To do.

  Since the organic photoreceptor of the present invention has the above-described structure, scattering of short-wavelength laser light of the organic photoreceptor having a surface layer containing fluororesin fine particles can be prevented. And white streak can be prevented, and an electrophotographic image with good sharpness can be formed.

  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. That is, the fluorine-containing resin fine particles having a small particle diameter easily form agglomerated particles, increase the scattering of short wavelength laser light, and deteriorate the sharpness, but the average primary particle diameter is 0.02 μm or more and less than 0.20 μm. The surface layer that improves the dispersibility of the fluorine-containing resin fine particles and has a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 ° can sufficiently prevent scattering of short-wavelength laser light. In addition, it is possible to provide an organic photoreceptor capable of preventing the generation of dash marks, black stripes, and white stripes and forming an electrophotographic image with good sharpness.

  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 a surface layer with good dispersibility that can prevent scattering of single-wavelength laser light, and to form a surface layer with a uniform surface energy with reduced contact angle variation with respect to water. It is possible to produce an organic photoreceptor that can prevent the generation of white stripes and can form an electrophotographic image with good sharpness.

  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 device, 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 between each other, it is difficult to uniformly disperse, contact angle variation is likely to increase, and the dash mark described above is likely to occur. Also, if the average primary particle size is greater than 0.20 μm, aggregated particles are likely to be formed due to sedimentation, surface contact angle variation is increased, dash marks are likely to occur, and image exposure such as short-wavelength laser light is scattered. And deteriorate 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. Adhesion increases and dash marks are likely to occur. Further, 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 sharpness 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. 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.

  An image forming apparatus 1 shown in FIG. 3 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. Yes.

  An automatic document feeder that automatically conveys the document is provided above the image reading unit A. The document placed on the document table 11 is separated and conveyed by the document conveyance roller 12 to the reading position 13a. The image is read. The document after the document reading is completed is discharged onto the document discharge tray 14 by the document transport roller 12.

  On the other hand, the image of the original when placed on the platen glass 13 is read at a speed v of the first mirror unit 15 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by the movement of the second mirror unit 16 including the two mirrors and the third mirror in the same direction at the speed v / 2.

  The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal) and then A / D converted, and the image processing unit B performs processing such as density conversion and filter processing. Then, the image data is temporarily stored in the memory.

  In the image forming unit C, as an image forming unit, a drum-shaped photoconductor 21 as an image carrier, a charging means (charging step) 22 for charging the photoconductor 21 on the outer periphery thereof, and a surface potential of the charged photoconductor. Potential detecting means 220 for detecting the color, developing means (development process) 23, transfer / conveying belt device 45 as transfer means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and photostatic means (photo-site charge). PCLs (precharge lamps) 27 as generating steps) are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. The photoconductor 21 uses the organic photoconductor of the present invention and is driven to rotate in the clockwise direction shown in the figure.

  After the rotating photosensitive member 21 is uniformly charged by the charging unit 22, an image based on an image signal called from the memory of the image processing unit B by an exposure optical system as an image exposure unit (image exposure step) 30 is used. Exposure is performed. The exposure optical system as the image exposure means 30 serving as a writing means uses a laser diode (not shown) as a light source, passes through a rotating polygon mirror 31, an fθ lens 34, and a cylindrical lens 35, and the optical path is bent by the reflection mirror 32 to perform main scanning. Therefore, image exposure is performed on the photoconductor 21 at the position Ao, and an electrostatic latent image is formed by rotation (sub-scanning) of the photoconductor 21. In one example of the present embodiment, the character portion is exposed to form an electrostatic latent image.

  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 electrostatic latent image on the photoconductor 21 is reversely developed by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21.

  In the image forming apparatus of the present invention, the latent image on the organophotoreceptor of the present invention is visualized by developing means using a toner containing an inorganic external additive of 0.1 to 1.0 μm and an inorganic external additive of 50 nm or less. At the time of imaging, the effect of the present invention, particularly the improvement effect of preventing the deterioration of a halftone image due to a dash mark or a scratch is great.

  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 and a colorant necessary for the composition of the toner at the time of association, and a toner component such as a release agent and a colorant 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 was added to stop the particle size growth, and the particle surface was smoothed while heating and stirring to control the shape, and the particles were heated and dried in a fluidized state while containing water, whereby a toner was obtained. 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.

  In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means for storing transfer paper P of different sizes. Further, a manual paper feeding unit 42 for manually feeding paper is provided on the side, and the transfer paper P selected from any of them is fed along the transport path 40 by the guide roller 43 and fed. The transfer paper P is temporarily stopped by a pair of paper feed registration rollers 44 that correct the inclination and bias of the transfer paper P to be transferred, and then fed again. The transport path 40, the pre-transfer roller 43a, and the paper feed path 46 The toner image on the photosensitive member 21 is transferred to the transfer paper P while being transferred to the transfer conveyance belt 454 of the transfer conveyance belt device 45 by the transfer electrode 24 and the separation electrode 25 at the transfer position Bo. Is, transfer sheet P is separated from the photosensitive member 21 surface, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the toner is fixed by heating and pressing. After the toner image has been fixed, the transfer paper P is discharged onto the paper discharge tray 64.

  The above describes the state in which image formation is performed on one side of the transfer paper. However, in the case of double-sided copying, the paper discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.

  Further, the transfer paper P is transported downward by the transport mechanism 178 and switched back by the transfer paper reversing unit 179, and the rear end portion of the transfer paper P becomes the leading end portion and transported into the duplex copying paper supply unit 130. The

  The transfer paper P is moved in a paper feed direction by a conveyance guide 131 provided in the double-sided copy paper supply unit 130, the transfer paper P is re-fed by the paper supply roller 132, and the transfer paper P is guided to the conveyance path 40. .

  Again, as described above, the transfer paper P is conveyed in the direction of the photosensitive member 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged onto the paper discharge tray 64.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Also good. In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device together with a photosensitive member, and a single unit that is detachable from the apparatus main body. It is good also as a structure which can be attached or detached using guide means, such as a rail of an apparatus main body.

  Next, FIG. 4 shows a color image forming apparatus using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means and an intermediate transfer body around the organic photoreceptor. 1 is a sectional view of the configuration of a laser beam printer). The belt-shaped intermediate transfer body 10 uses an elastic body having a medium resistance.

  Reference numeral 21 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotated at a predetermined peripheral speed in the counterclockwise direction indicated by an arrow.

  In the rotation process, the photosensitive member 21 is uniformly charged to a predetermined polarity and potential by the charging unit 22, and then modulated by the image exposure unit 30 (not shown) corresponding to the time-series electric digital pixel signal of the image information. An electrostatic latent image corresponding to a yellow (Y) color component image of a target color image is formed by receiving image exposure with scanning exposure light or the like by a laser beam.

  Next, the electrostatic latent image is developed with yellow toner which is the first color by yellow (Y) developing means (yellow color developing device) 23Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 23M, 23C, and 23Bk are turned off and do not act on the photosensitive member 21. The first color yellow toner image is not affected by the second to fourth developing units.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is rotationally driven in the clockwise direction at the same peripheral speed as the photosensitive member 21.

  The yellow toner image of the first color formed and supported on the photoreceptor 21 is applied to the intermediate transfer body 70 from the primary transfer roller 24a in the process of passing through the nip portion between the photoreceptor 1 and the intermediate transfer body 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoconductor 21 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 26.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 24b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  The primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 21 to the intermediate transfer member 70 has a polarity opposite to that of the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 21 to the intermediate transfer member 70, the secondary transfer roller 24b and the intermediate transfer member cleaning means 26A can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer body 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 24b is brought into contact with the belt of the intermediate transfer body 70. At the same time, the transfer material P is fed from the pair of paper supply registration rollers 44 through the transfer sheet guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 24b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 24b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 50 and fixed by heating.

  The organophotoreceptor of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, but further displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. The present invention can be widely applied to such devices.

  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 Company) 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 and the type and amount of fluorine resin particles in charge transport layer 2 (CTL2) 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 was mounted on a commercially available color printer, magiccolor 2200 Desk Laser (manufactured by Minolta EMS Co., Ltd.), and the short wavelength laser light source shown below was used as an image exposure light source, and sharpness evaluation and durability test were performed. Specifically, a total of 20,000 character images and halftone images were printed and evaluated at the start and every 5000 sheets. Evaluation items and evaluation criteria are shown below.

  The process conditions for the color printer were as follows.

Charger: Sawtooth electrode Exposure device: Semiconductor laser (oscillation wavelength: 405 nm)
Development: Nonmagnetic toner (polymerized toner) having an average particle size of 4.5 μm, toner containing 0.3 μm strontium titanate and 15 nm hydrophobic silica external additives, reversal development method Transfer: use of intermediate transfer belt Cleaning: Cleaning blade Fixing: Heat fixing Process speed: 100mm / sec
(Sharpness)
At the start of evaluation, 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 unevenness)
A: Through the printing of 20,000 sheets, no streak-like unevenness was observed in any of the halftone images that coincided with the scratches on the photoreceptor surface;
○: A slight streak-like unevenness was observed on a part of the surface of the photoreceptor through 20,000 sheets of printing, but no streak-like unevenness was observed in the halftone image;
X: During printing of 20,000 sheets, clear streak-like unevenness was observed on the entire surface of the halftone image corresponding to the scratch on the surface of the photoreceptor.

(Image blur)
A: No image blur was observed after printing 5,000 sheets (good)
○: Several partial image blurs (less than 10) occurred after printing 5,000 sheets, but there was no practical problem (no problem in practical use)
X: During printing of 5,000 sheets, 10 or more partial image blurs or 1 or more image blurs in a wide range occurred (practically problematic)
Dash Mark The occurrence of a dash mark (small comet-like streak image) on a halftone image was determined according to the following criteria.

A: 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 photoconductors 1 to 3, 6 to 8, and 10 to 12 have a sharpness of rank C or higher, and image unevenness, image blur, dash mark, and sharpness are improved. On the other hand, the photoreceptor 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, has a large contact angle variation of 2.2, and has a high sharpness. Dash marks are generated, inferior to 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, sharpness is inferior to rank D, and dash marks are generated. In addition, the scattering of laser exposure is increased and the sharpness is also deteriorated. In addition, the photoreceptor 9 in which the content of PTEF-1 in the surface layer (= charge transport layer 2) is reduced and the contact angle is lowered to 88 is inferior in sharpness to rank D, and image unevenness and dash marks And sharpness 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. The measurement results of the contact angles and contact angle variations of these photoreceptors 13 to 16 (contact angle variations are expressed in absolute values) were obtained as shown in Table 3.

<< 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 unevenness, 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 view in which functions of an image forming apparatus of the present invention are incorporated. 1 is a cross-sectional view of a color image forming apparatus using an organic photoreceptor of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Photoconductor 22 Charging means 23 Developing means 24 Transfer pole 25 Separation pole 26 Cleaning device 30 Exposure optical system 45 Transfer conveyance belt apparatus 50 Fixing means 250 Separation claw unit

Claims (8)

In an organic photoreceptor used for an image forming apparatus that irradiates a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm on an organic photoreceptor as an image exposure light source, the average primary particle size is 0.02 μm or more and less than 0.20 μm. An organic photoreceptor having a surface layer containing fluorine-containing resin fine particles. In an organic photoreceptor used for an image forming apparatus that irradiates a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm on an organic photoreceptor as an image exposure light source, the average primary particle size is 0.02 μm or more and less than 0.20 μm. An organophotoreceptor comprising fluororesin fine particles, having a surface layer having a contact angle with water of 90 ° or more and a variation in contact angle of ± 2.0 °. 3. The organic photoconductor according to claim 1, wherein the organic photoconductor comprises a charge generation layer and a plurality of charge transport layers on a conductive support, and the uppermost layer of the plurality of layers 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. The organic photoreceptor according to any one of claims 1 to 6, a charging unit that uniformly charges the organic photoreceptor, a latent image forming unit that forms an electrostatic latent image on the charged organic photoreceptor, Developing means for developing an electrostatic latent image on the organic photoreceptor, transfer means for transferring a toner image visualized on the organic photoreceptor onto a transfer material, and on the organic photoreceptor after transfer At least one of a charge removing means for removing charges and a cleaning means for removing toner remaining on the organic photoconductor after transfer is integrally supported, and can be detachably attached to the image forming apparatus main body. Process cartridge characterized by. An image forming apparatus, wherein an electrophotographic image is formed using the organophotoreceptor according to claim 1.

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