JP4209759B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms a high-definition and high-definition image. Specifically, in an image forming apparatus in which writing is performed with a beam diameter of 50 μm or less, the electrophotographic photosensitive member used in the image forming apparatus contains at least a titanyl phthalocyanine crystal having a specific crystal type and a specific particle size. The present invention relates to an image forming apparatus which is an electrophotographic photosensitive member obtained by sequentially laminating a charge transport layer.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light is markedly improved in print quality and reliability. This digital recording technique is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, the demand is expected to increase further in the future. In addition, with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is rapidly progressing.

  In recent years, the above-mentioned printers and copiers are required to improve the image quality of devices including colorization. There are two problems in improving the image quality in a digital machine. One is how to uniformly form an electrostatic latent image with minute dots, and the other is how to reduce various abnormal images.

  Regarding the former, it is necessary to develop a peripheral technique for making the write beam system for forming the electrostatic latent image smaller and making the most of it. Regarding the latter, the generation of abnormal images due to deterioration of the photoconductor is the main cause, and the photoconductor that has acquired the high durability and high stabilization technology of the photoconductor and understands the characteristics of the process to be used. Development is required.

  As the former technique, two directions are presented. One is a technique using short-wavelength laser light, and a writing light source having an oscillation wavelength of 450 nm or less, called a blue laser that oscillates in purple to blue, has been developed. Since this has high energy and the beam diameter can be easily reduced, high-density writing is possible. This makes it possible to realize writing with a smaller beam diameter than writing using a light source so far.

  However, since this writing light source is shorter than the light wavelength of an exposure member that has been used in the past, it creates several problems. First, most of the charge transport materials used in the charge transport layer that have been used so far have a structure in which the π-conjugated system is expanded to improve transport properties, and the color of the material itself is It exhibits a yellow color and has an absorptivity at the wavelength of writing light by the short wavelength light source. For this reason, the charge transport material blocks the writing light, and the photosensitivity of the photoreceptor is lowered. Further, since the charge transport material itself absorbs light, the charge transport material promotes deterioration through an excited state, thereby degrading the function of the photoreceptor itself. The second is the problem of charge generation materials. In general, the electrophotographic photosensitive member so far has been used in a functionally separated type photosensitive layer structure in which a charge transport layer containing a charge transport material is laminated on a charge generation layer containing a charge generation material. As described above, since most of the charge transport materials that have been used so far are yellow, light having a wavelength shorter than about 450 nm (for example, ultraviolet light emitted from a charging member, ultraviolet light emitted from a fluorescent lamp, etc.). Is absorbed by the charge transport layer and does not pass through the charge generation layer, and in fact, the charge generation layer (charge generation material) has been protected. Light on the shorter wavelength side than 450 nm has high energy, and also has surplus energy that is higher than the energy necessary for generating optical carriers.

  FIG. 1 shows a schematic diagram of a photocarrier generation mechanism using an organic charge generating material. As shown in FIG. 1, the generation of photocarriers in the organic charge generating substance is through the lowest excited singlet state (S1). The charge generation material existing in the ground state (S0) is excited to an excited state by light absorption. At this time, the height (potential) to be launched energetically differs depending on the light energy (that is, wavelength). The charge generating material that has obtained an energy higher than the energy difference between S0 and S1 is once launched to a higher excited state (S *), and is normally thermally relaxed to the S1 state. Is generated. At this time, energy higher than the energy level of S1 (energy difference between S1 and S *) is surplus energy, and may be used for other reactions without being alleviated thermally. The excited state of the organic substance is a very active state. Besides being thermally relaxed and settled in the S1 state, the surplus energy is used to react with other substances (oxidation, decomposition, etc.) or the same. It also binds between molecules and changes the molecular structure (such as isomerization). Thus, considering only the reactive element process of photocarrier generation, the surplus energy is actually harmful and requires a high chemical stability for the charge generation material.

  From the above, when writing using a short wavelength laser beam is used, it is necessary to develop a main material (charge generating substance, charge transporting substance) constituting the photosensitive member.

  Another technique related to writing light is a technique that uses an existing light source (such as a semiconductor laser (LD)) and optically narrows the beam diameter of light emitted from the light source. This technology requires the development of an optical system (lens, mirror, etc.). Recently, the beam diameter can be reduced to 50 μm or less by using an LD light source generally used in digital image forming apparatuses so far. (For example, Patent Document 20).

  The development of such a writing technique makes it possible to develop an existing material technique in developing a photoreceptor, which is very advantageous in terms of cost.

  With the development of the optical system in the image forming apparatus as described above, the writing diameter can be made much smaller than the conventional one (approximately 60 to 70 μm or more). This has led to the possibility of reducing the dot diameter of the electrostatic latent image formed on the photoreceptor. However, the electrostatic latent image is formed by canceling the charge applied to the photosensitive member by the reverse charge generated by writing, and a small-diameter dot is simply formed by using a small-diameter beam. However, it is also necessary to devise to make use of the small-diameter beam forming technology.

  That is, although the beam system irradiated onto the charge generation layer by writing with a small-diameter beam is certainly small, optical carriers are generated at a high density in a small area because of the high-density writing. These photocarriers are generated as a pair of holes and electrons, but move to the surface of the photoreceptor and the electrode (conductive support) by the electric field applied to the photoreceptor. At this time, the moving direction is determined by the polarity applied to the surface of the photoconductor. However, in the case of the function-separated organic laminated photoconductor, a negative polarity is generally applied to the surface. Will proceed in the electrode direction.

  It is known that when charges of the same polarity are close to each other, Coulomb repulsion is caused by the mutual charges, and the case of a photoconductor is no exception. In particular, when high-density writing is performed as described above, photocarrier generation is performed at high density. Therefore, if charges are not moved smoothly, recombination by holes and electrons (results in a decrease in carrier generation efficiency) In addition to this, a problem arises in that the dots spread when moving through the charge transport layer. As a result, the dot diameter of the electrostatic latent image formed on the surface of the photosensitive member is increased even if it is intended to write with a small diameter beam (see FIG. 2).

  FIG. 3 shows the relationship between the electric field strength applied to the photoreceptor and the dots developed from the electrostatic latent image. FIG. 3 shows a toner image when developed using a toner having a sufficiently small particle diameter. However, when the electric field strength is low, the dots are large and blurred. This shows the result that carriers generated in the charge generation layer spread due to Coulomb repulsion when crossing the charge transport layer, and the potential contrast corresponding to the writing portion and the non-writing portion on the surface of the photoreceptor is sufficiently high. This shows the results that could not be obtained. Therefore, when forming minute dots by writing such a small-diameter beam, the electric field strength applied to the photoreceptor must be set high. According to the study by the present inventors, application of an electric field strength of 30 V / μm or more is necessary for a normal electrophotographic photosensitive member having a charge transport layer thickness of about 30 μm or less.

  This electric field strength of 30 V / μm or higher is set higher than the normal applied electric field strength, and increases the stress on the photoreceptor. FIG. 4 shows the relationship between the electric field strength applied to the photoreceptor and the background stain. The scumming rank in the figure indicates the level of scumming, and the greater the number, the better the level of scumming. As can be seen from the figure, an increase in the electric field strength promotes the occurrence of background staining, and the background contamination and dot reproducibility (formation of minute dots) have a trade-off relationship with respect to the field strength. Therefore, in order to improve the reproducibility of the fine dots as described above, a photoconductor having a strong anti-smudge property is required.

  In addition, in order for the beam written in the charge generation layer to generate a homogeneous charge, the charge generation layer itself needs to be a fairly homogeneous body. The charge generation layer is usually constituted by a form in which an organic pigment as a charge generation material is dispersed in a binder resin. Therefore, it is essentially a heterogeneous body. However, in such a dispersion film, if the dispersion is sufficiently carried out to some extent or if the pigment particles themselves are present in a sufficiently small state, the behavior of a homogeneous body is optically observed. For this reason, the pigment particles constituting the charge generation layer of the photoreceptor must have a sufficiently small particle size with respect to the writing wavelength.

Therefore, the following items are necessary in an image forming apparatus that forms fine dots using a writing light source having a beam diameter of 50 μm or less.
(1) Since high-density writing is performed per unit area, the photoconductor (charge generating material) used has a high photocarrier generating ability.
(2) The electric field intensity applied to the photosensitive member is sufficiently increased so that the charge is not diffused due to the influence of Coulomb repulsion when the charge is transferred (30 V / μm or more is required).
(3) Since application of high electric field strength tends to cause scumming, a photoconductor with high scumming resistance is required.
(4) It has sufficient homogeneity for writing of a small-diameter beam. For this reason, the charge generation material contained in the charge generation layer should be sufficiently small.

  The above problems are all related to the photosensitive layer (charge generation layer) except for the transparency of the charge transport material, and the development of photoconductors for image forming devices intended for the formation of fine dots by high-density writing is a charge generation. It shows whether it depends on the development of the substance.

  In the present application, the field strength defined by the following formula is used.

Electric field strength (V / μm)
= Surface potential of unexposed portion of photoreceptor at development position (V) / photosensitive layer thickness (μm)
As a charge generating material for photoreceptors having high sensitivity and high speed response, a diffraction peak (± 0.2 °) with a Bragg angle 2θ for CuKα rays (wavelength 1.542 mm) has a maximum diffraction peak at least 27.2 °. It is known to use a titanyl phthalocyanine crystal having (see Patent Document 1).

  This specific crystal type has a very high carrier generation function and can be effectively used as a charge generation material for a photoreceptor for a high-speed image forming apparatus. However, this crystal type has a problem that it is low in stability as a crystal and easily undergoes a crystal transition due to mechanical stress such as dispersion and thermal stress. The sensitivity is very low compared to the previous crystal type, and when a part of the crystal undergoes crystal transition, sufficient photocarriers cannot be generated. Further, when the photoreceptor is used repeatedly, there is a problem that the chargeability is likely to be lowered and the negative residue is likely to be caused. In addition, there is a problem that an abnormal image called a smudge image, which is a problem inherent to negative / positive development, is likely to occur.

  In addition, writing with a small-diameter beam is intended to write at high density. However, as will be described later, there may be a problem of reciprocity failure of the sensitivity of the photosensitive member at high density, or the writing (electrostatic latent image) dot outline on a small-diameter beam may be blurred.

  Furthermore, when forming a small-diameter dot using a small-diameter beam as described above, if the charge generation layer does not have a sufficiently homogeneous structure, the outline of the fine dot will not be clear, and the advantages of the small-diameter beam are not necessarily obtained. Thus, homogenization of the charge generation layer (that is, miniaturization of the charge generation material particles) was not considered.

In this way, the development of a photoconductor has been developed in response to the process restrictions (requests) that arise in order to design an image forming apparatus that realizes high-density writing by forming a small-diameter beam using innovative optical system technology. The situation is not sufficient, and the actual situation is that the development of a photoreceptor for realizing stable repeated image formation is not sufficient.
JP 2001-19871 A JP-A-6-293769 JP-A-8-110649 JP 52-36016 A Japanese Patent Laid-Open No. 3-109460 JP 2000-206723 A JP 2001-340001 A Japanese Patent Laid-Open No. 61-239248 JP-A-5-113688 JP-A-1-299874 (Patent No. 2512081) Japanese Patent Laid-Open No. 3-269064 (Japanese Patent No. 2854682) Japanese Patent Laid-Open No. 2-8256 (Japanese Patent Publication No. 7-91486) JP-A 64-17066 (Japanese Patent Publication No. 7-97221) Japanese Patent Laid-Open No. 11-5919 (Patent No. 3003664) Japanese Patent Laid-Open No. 3-255456 (Patent No. 3005052) JP-A-5-134437 (Patent No. 3196260) JP 2001-187794 A JP-A-5-94049 JP 2002-277801 A Japan Hardcopy '89 Proceedings p. 103 1989 Moser et al. “Phthalogicane Compounds” (1963), “The Phthalogicanes” (1983)

  Accordingly, an object of the present invention is to provide an image forming apparatus that performs high-density writing using a small-diameter beam and outputs an image in a stable state without generating an abnormal image when repeatedly used.

  Specifically, an image forming apparatus that uses a light source having a beam diameter of 50 μm or less as a writing light source to form a high-definition image, by using a photoreceptor containing a specific crystal type titanyl phthalocyanine crystal. Another object of the present invention is to provide an image forming apparatus that maintains the high sensitivity inherent to titanyl phthalocyanine, is highly durable, and can output a high-speed image.

  In the image forming apparatus using a light source having a beam diameter of 50 μm or less, the present inventors have made a number of studies in order to form an image with few abnormal images even during repeated use. Is an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, and a diffraction peak of a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm) in the charge generation layer ( ± 0.2 °) having a maximum diffraction peak at least 27.2 °, and further having major peaks at 9.4 °, 9.6 °, and 24.0 °, and the lowest angle As a diffraction peak, it has a peak at 7.3 °, has no peak between the peak at 7.3 ° and the peak at 9.4 °, and further has a peak at 26.3 °, And the average particle size of the primary particles is 0.25 It has been found that the above problems can be solved by including a titanyl phthalocyanine crystal of less than μm.

  It was understood that the above-mentioned problem of background contamination in image formation was due to a charge leak phenomenon in the photoreceptor. Although the detailed reason for the effect of the present invention is not clear, as for soil contamination, the titanyl used in the present invention is compared with other titanyl phthalocyanine crystals having a maximum diffraction peak at 27.2 ° known so far. It is presumed that it originates from the high chemical stability of phthalocyanine crystals and is due to the reduction in the occurrence of soiling.

  In addition, the unclearness of the fine dot outline is based on the non-uniformity in the charge generation layer. If the charge generation material particles in the charge generation layer are sufficiently fined as in the present invention, optical charge generation is performed. The layer has a homogeneous structure and the contours in the latent image dots are very sharp. This is a problem that comes from the writing beam size that the particle size must be further reduced by the amount that the beam diameter is smaller than the beam diameter as the light source that has been used so far. The charge generation layer corresponding to the writing beam size is considered to be a problem that cannot be handled.

  FIGS. 5 and 6 are schematic views of electrostatic latent images when writing is performed with the same size beam when the size of the charge generation material particles contained in the charge generation layer is small and large, respectively. . As shown in FIG. 5, when the particle size of the charge generation material is fine and the particle size distribution is narrow, the outline of the dots is sharp, while the particle size is large and the particle size distribution is wide (or coarse particles are In the case of (including) (FIG. 6), the outline of the dot collapses and lacks clarity. Therefore, by using a charge generation layer having a fine particle size and a narrow particle size distribution, a high-definition dot formation technique can be more effectively implemented using a small particle size toner.

  Furthermore, when a small-diameter beam is formed by devising an optical system, the number of incident photons per unit area increases, and the number of photons per unit time irradiated to the charge generation material increases. As a result, the carrier generation efficiency is reduced when the electric field is low, and the surface charge cannot be sufficiently reduced. This is due to the fact that reciprocity failure occurs in the generation of carriers.

  There are several reasons for reciprocity failure. For example, (i) excitons generated in the charge generation particles reach the particle surface and become deactivated before free carriers, and (ii) before the generated free carriers pass carriers to the charge transport material. Recombination (geminate / recombination). It is thought that these causes originate from the fact that the size of the charge generation material particles is too large and the surface area is not sufficient for the number of photons received in proportion to the volume (cross-sectional area with respect to the writing direction). .

  FIG. 7 shows the light attenuation characteristics of two types of photoconductors when the particle size of the charge generating material used in the photoconductor is changed. When the particle size is large (A in FIG. 7), the attenuation of light attenuation occurs in the low electric field region (region where the photoreceptor surface potential is low), in addition to the slow light attenuation rate. . As a result, the saturation decay potential is high and saturated. On the other hand, when the particle size is controlled to be sufficiently small (B in FIG. 7), the tail of light attenuation is good, the light is sufficiently attenuated even at a low electric field, and the saturation potential is also low.

  As for the reason why the above-mentioned problems do not occur in the present invention, the titanyl phthalocyanine crystal used in the present invention has a high carrier generation ability, including high chemical stability as described above, and further sufficient It is considered that the reciprocity failure phenomenon is suppressed because the fine particles are applied.

  As described above, although a basic design for achieving high speed has been performed, an effective photoconductor that takes advantage of its features has not been developed, so stable image formation cannot be realized, and various image formation However, the present invention solves this problem.

That is, the said subject is achieved by the following (1)-(12).
(1) An electrophotographic photoreceptor comprising at least a charge transport layer and a charge generation layer having a titanyl phthalocyanine crystal as a charge generation material on a conductive support, and the electrophotographic photoreceptor has an electrophotographic photoreceptor of 30 V / μm or more. In the image forming apparatus provided with charging means for applying electric field strength and exposure means for irradiating the electrophotographic photosensitive member with writing light using a light source having a beam diameter of 50 μm or less, the titanyl phthalocyanine crystal has CuKα rays (wavelength as diffraction peak of Bragg angle 2 [Theta] (± 0.2 °) with respect to 1.542 Å), having a 27.2 maximum diffraction peak, 9.4 °, 9.6 ° and 24.0 ° major peaks the a, has a 7.3 ° peak as a diffraction peak of the lowest angle side, it does not have a peak between the peaks and the 9.4 ° peak of 7.3 °, and 26. 3 ° It has a click, the titanyl phthalocyanine crystal as a diffraction peak of Bragg angle 2 [Theta] (± 0.2 °) with respect to CuKα rays (wavelength 1.542 Å), at least 7.0-7.5 ° maximum diffraction peak Amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine having a half-width of the diffraction peak of 1 ° or more and an average primary particle size of 0.1 μm or less is mixed with an organic solvent in the presence of water. By performing crystal conversion by stirring, and converting the crystals obtained by fractionating with the organic solvent before the average particle size of the primary particles after the crystal conversion grows larger than 0.25 μm. are manufactured, images formed average particle size of the primary particles of the titanyl phthalocyanine crystal you wherein the Ru der below 0.25μm apparatus.
As a result, it is possible to obtain an image forming apparatus including an exposure unit that uses a light source having an excellent electrophotographic characteristic and a beam diameter of 50 μm or less. Furthermore, it is possible to obtain an image forming apparatus using an LED having excellent electrophotographic characteristics as a light source.
(2) The titanyl phthalocyanine crystal is characterized in that the peak intensity at 26.3 ° is in the range of 0.1 to 5% with respect to the peak intensity at the maximum diffraction peak of 27.2 °. The image forming apparatus according to item (1).
As a result, it is possible to obtain an image forming apparatus including an exposure unit that uses a light source having an excellent electrophotographic characteristic and a beam diameter of 50 μm or less.
(3) before Symbol charge transport layer, wherein the first (1) or any one of the subsection (2), characterized in that it contains a polycarbonate having a triarylamine structure in a main chain and / or side chain Image forming apparatus.
As a result, it is possible to obtain an image forming apparatus including an exposure unit using a light source having a beam diameter of 50 μm or less while maintaining wear resistance and having excellent electrophotographic characteristics.
( 4 ) The image forming apparatus according to any one of (1) to ( 3 ), wherein the electrophotographic photosensitive member has a protective layer as an outermost layer.
As a result, it is possible to obtain an image forming apparatus including an exposure unit using a light source having a beam diameter of 50 μm or less while maintaining wear resistance and having excellent electrophotographic characteristics.
( 5 ) The image forming apparatus according to item ( 4 ), wherein the protective layer contains a metal oxide having a specific resistance of 10 ¹⁰ Ω · cm or more.
As a result, it is possible to obtain an image forming apparatus provided with an exposure unit using a light source having a beam diameter of 50 μm or less that is less likely to cause image blurring while maintaining wear resistance.
(6) The protective layer is first characterized that you containing a polymer charge transport material (4) or (5) The image forming apparatus according to claim.
As a result, it is possible to obtain an image forming apparatus including an exposure unit using a light source having a beam diameter of 50 μm or less while maintaining wear resistance and having excellent electrophotographic characteristics.
(7) The protective layer includes a first (4), characterized that you containing a binder resin having a crosslinked structure through (6) The image forming apparatus according to any one of claims.
As a result, a photoconductor having high wear resistance can be obtained, and as a result, it is possible to obtain an image forming apparatus provided with an exposure unit using a light source having a beam diameter of 50 μm or less that is excellent in durability.
(8) a binder resin having a pre-listen bridge structure, the image forming apparatus according to the (7), characterized in that it has a charge transporting moiety.
As a result, it is possible to obtain an image forming apparatus including an exposure unit that uses a light source having a beam diameter of 50 μm or less that greatly contributes to the wear resistance of the photosensitive member and has excellent durability.
( 9 ) The image forming apparatus according to any one of (1) to ( 8 ), wherein the surface of the conductive support is anodized.
As a result, the barrier property of the photocarrier generated in the photoconductor is improved, and as a result, it is possible to obtain an image forming apparatus including an exposure unit using a light source having a beam diameter of 50 μm or less having good electrophotographic characteristics. Become.
As (10) the imaging element, the charging unit, the exposing unit, developing unit, transfer unit, and a (1), characterized in that the imaging element consisting of the electrophotographic photosensitive member was arrayed to (9) The image forming apparatus according to claim 1.
As a result, it is possible to obtain an image forming apparatus including an exposure unit that uses a light source having a beam diameter of 50 μm or less that supports full-color printing.
(11) before Symbol band conductor means includes a first (1) and applying an alternating superimposed voltage to (10) the image forming apparatus according to any one of claims.
As a result, it is possible to stabilize the charging of the photosensitive member and to obtain a high-quality image.
(12) the charging unit, the exposing unit, that one of the means selected from the group consisting of the developing means and cleaning means and the electrophotographic photosensitive member is detachably mounted the process cartridge integrally The image forming apparatus according to any one of (1) to ( 11 ), which is characterized.
Accordingly, an image forming apparatus with improved handling performance can be obtained by the user, and an exposure unit using a light source with a beam diameter of 50 μm or less that can be selected according to the purpose is provided. An image forming apparatus can be obtained.

  As described above, as is clear from the detailed and specific invention, according to the present invention, it is an image forming apparatus that outputs an extremely high-speed image. An image forming apparatus that outputs an image with high resolution is provided.

(Image forming apparatus in the present invention)
First, the image forming apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 8 is a schematic diagram for explaining the image forming apparatus of the present invention, and modifications as described later also belong to the category of the present invention.

In FIG. 8, the photoreceptor (1) is provided with a photosensitive layer including at least a charge generation layer and a charge transport layer on a conductive support, and the charge generation layer has a Bragg angle with respect to CuKα rays (wavelength 1.542 mm). As the 2θ diffraction peak (± 0.2 °), it has a maximum diffraction peak at least 27.2 °, and further has major peaks at 9.4 °, 9.6 °, 24.0 °, and The lowest diffraction peak has a peak at 7.3 °, and no peak between the peak at 7.3 ° and the peak at 9.4 °, and further at 26.3 °. It contains titanyl phthalocyanine crystals having an average particle size of primary particles having a peak of 0.25 μm or less. The photosensitive member (1) has a drum shape, but may be a sheet or an endless belt.

  Any known member can be used as the charging charger (3) as long as it can sufficiently charge the photosensitive member. Among them, a scorotron charging member, a contact charging member (roller shape), or a charging member in which the surface of the photosensitive member and the charging member surface are arranged close to 100 μm or less is preferably used. When the dot reproducibility is prioritized for high-definition image formation, an electric field strength of 30 V / μm or more is applied to the photoreceptor by this charging member. The higher the electric field strength applied to the photoconductor, the better the dot reproducibility. However, there is a possibility of causing problems of dielectric breakdown of the photoconductor and carrier adhesion at the time of development, and the upper limit is about 60 V / μm or less. Preferably, it is 50 V / μm or less.

  In addition, the image exposure unit (5) was devised with an optical system capable of ensuring high brightness such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL) and capable of writing at 50 μm or less. A light source is used.

  The device of the above-described optical system is a technique for reducing the writing beam diameter by, for example, a method described in Patent Document 19, and in the present invention, if the writing beam can be formed to 50 μm or less, Any method can be used.

  Here, the beam diameter of 50 μm or less will be described. Usually, writing light emitted from an optical element is applied to the surface of the photoreceptor through an optical system (mirror or lens). The writing beam does not become a perfect circle, but has a slightly flattened shape like an ellipse. The writing size is determined in the major axis direction of the ellipse, and the beam diameter in the present invention refers to the length of the major axis.

Further, such a beam has a Gaussian distribution from the center of light emission, and has a shape as described in Patent Document 19 (FIG. 6). Therefore, the above-mentioned major axis cannot be determined without defining the light intensity, but the definition generally used in the present invention is used. That is, the major axis of the region where the amount of light is larger than 1 / (e ² ) of the maximum intensity of the exposure beam is defined as the beam diameter of the present invention.

  Depending on the resolution of the light source (writing light), the resolution of the formed electrostatic latent image, and thus the toner image, is determined. The higher the resolution, the clearer the image. However, if writing is performed with a higher resolution, it takes longer to write, so if there is one writing light source, this writing speed will be limited by the drum linear speed (process speed). . Therefore, when there is one writing light source, a resolution of about 2400 dpi is the upper limit. When there are a plurality of writing light sources, each may be in charge of a writing area, and the upper limit is substantially “2400 dpi × number of writing light sources”. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and long wavelength light of 600 to 800 nm. Therefore, the specific crystal type phthalocyanine pigment which is a charge generation material used in the present invention has high sensitivity. Used well from showing.

  The developing unit (6) can handle both normal development and reversal development depending on the charging polarity of the toner used. When toner having a polarity opposite to the charged polarity of the photoreceptor is used, normal development is used. When toner having the same polarity is used, the electrostatic latent image is developed by reversal development. Depending on the light source used in the previous image exposure unit, in the case of a digital light source used in recent years, considering the life of the light source, etc. A reversal development system in which development is performed is advantageous. There are two methods, a one-component method in which development is performed using only toner and a two-component method in which a two-component developer composed of toner and carrier is used.

  The transfer charger (10) may be a transfer belt or a transfer roller, but it is desirable to use a contact type such as a transfer belt or transfer roller that generates less ozone. As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used, but the transfer charge amount can be kept constant, and a constant voltage with excellent stability can be used. The current method is more desirable.

  In addition, the toner image formed on the photosensitive member is transferred onto the transfer paper to become an image on the transfer paper. At this time, there are two methods. One is a method of directly transferring a toner image developed on the surface of the photoreceptor as shown in FIG. 8 to the transfer paper, and the other is that the toner image is once transferred from the photoreceptor to the intermediate transfer body, and this is transferred to the transfer paper. This is a method of transferring to Either case can be used in the present invention.

  As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.

  Use light sources such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LDs), and electroluminescence (ELs) as light sources such as static elimination lamps (2). Can do. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Such a light source or the like irradiates the photosensitive member with light by providing a process such as a transfer process, a charge eliminating process, a cleaning process, or a pre-exposure using light irradiation in addition to the process shown in FIG.

  When the AC (alternating current) component is used in a superposed manner in the previous charging method, or when the residual potential of the photosensitive member is small, this static elimination mechanism can be omitted. Further, instead of optical static elimination, an electrostatic static elimination mechanism (for example, a static elimination brush with a reverse bias applied or grounded) can be used. In the figure, 8 is a registration roller, 11 is a separation charger, and 12 is a separation claw.

  In addition, the toner developed on the photoreceptor (1) by the developing unit (6) is transferred to the transfer paper (9), but when toner remaining on the photoreceptor (1) is generated, a fur brush ( 14) and the blade (15) to remove from the photoreceptor. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

(Tandem image forming device)
FIG. 9 is a schematic diagram for explaining the tandem-type full-color image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.

  Also in the image forming apparatus shown in FIG. 9, a light source designed to have a beam diameter of 50 μm or less is used.

  In FIG. 9, reference numerals (16Y), (16M), (16C), and (16K) denote drum-shaped photoconductors, and the photoconductors include at least a charge generation layer and a charge transport layer on a conductive support. The charge generation layer has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm), and further 9 .4 °, 9.6 °, 24.0 °, the peak at 7.3 ° as the lowest diffraction peak, and the 7.3 ° peak. It contains titanyl phthalocyanine crystals having no peak between the 9.4 ° peaks, and further having an average particle size of 0.25 μm or less of primary particles having a peak at 26.3 °.

  The photosensitive members (16Y), (16M), (16C), and (16K) rotate in the direction of the arrow in the figure, and charging members (17Y), (17M), (17C), (17K) at least in the order of rotation therearound. ), Developing members (19Y), (19M), (19C), (19K), and cleaning members (20Y), (20M), (20C), (20K) are arranged. The charging members (17Y), (17M), (17C), and (17K) are charging members that constitute a charging device for uniformly charging the surface of the photoreceptor. From an exposure member (not shown) from the back side of the photoreceptor between the charging members (17Y), (17M), (17C), (17K) and the developing members (19Y), (19M), (19C), (19K). Laser beams (18Y), (18M), (18C), and (18K) are irradiated so that an electrostatic latent image is formed on the photoconductors (16Y), (16M), (16C), and (16K). It has become. Then, the four image forming elements (25Y), (25M), (25C), and (25K) centering on such photoconductors (16Y), (16M), (16C), and (16K) serve as transfer materials. They are juxtaposed along the transfer conveyance belt (22) which is a conveyance means. The transfer / conveying belt (22) includes developing members (19Y), (19M), (19C), (19K) and cleaning members (20Y) of the image forming units (25Y), (25M), (25C), (25K). , (20M), (20C), and (20K) are in contact with the photosensitive member (16Y), (16M), (16C), and (16K), and contact the back side of the photosensitive member side of the transfer conveyance belt (22). Transfer brushes (21Y), (21M), (21C), and (21K) for applying a transfer bias are arranged on the surface (back surface). Each of the image forming elements (25Y), (25M), (25C), and (25K) has a different toner color inside the developing device, and the others have the same configuration.

In the full-color image forming apparatus having the configuration shown in FIG. 8, the image forming operation is performed as follows. First, in each of the image forming elements (25Y), (25M), (25C), and (25K), electrostatic latent images are formed on the photoreceptors (16Y), (16M), (16C), and (16K). Then, each of the photoreceptors (16Y), (16M), (16C), and (16K) rotates, and the photoreceptor is charged by the charging members (17Y), (17M), (17C), and (17K). . At this time, in order to form a high-definition latent image, the photoconductor is charged so that the electric field strength is 30 V / μm or more (60 Vμm or less, preferably 50 V / μm or less). Is written at a resolution of 1200 dpi or more (preferably 2400 dpi or more) with a laser beam (18Y), (18M), (18C), or (18K) having a beam diameter of 50 μm or less at the exposed portion (not shown). Thus, an electrostatic latent image corresponding to each color image to be created is formed. In this case as well, 2400 dpi writing is generally the upper limit for one writing light source.

  Next, the latent image is developed by the developing members (19Y), (19M), (19C), and (19K) to form a toner image. Developing members (19Y), (19M), (19C), and (19K) are developing members that perform development with toners of Y (yellow), M (magenta), C (cyan), and K (black), respectively. The toner images of the respective colors created on the four photoconductors (16Y), (16M), (16C), and (16K) are superimposed on the transfer paper. The transfer paper (26) is fed out from the tray by a paper feeding roller (not shown), temporarily stopped by a pair of registration rollers (23), and transferred and conveyed (22) in synchronization with the image formation on the photosensitive member. ). The transfer paper (26) held on the transfer conveyance belt (22) is conveyed, and each color is in contact with each photoconductor (16Y), (16M), (16C), (16K) (transfer section). The toner image is transferred.

  The toner image on the photoconductor includes transfer bias applied to the transfer brushes (21Y), (21M), (21C), and (21K) and the photoconductors (16Y), (16M), (16C), and (16K). The image is transferred onto the transfer paper (26) by an electric field formed from the potential difference. Then, the recording paper (26) on which the four color toner images are passed through the four transfer sections is conveyed to the fixing device (24), where the toner is fixed, and is discharged to a paper discharge section (not shown).

  Further, residual toner remaining on each of the photoconductors (16Y), (16M), (16C), and (16K) without being transferred by the transfer unit is removed from the cleaning devices (20Y), (20M), (20C), ( 20K).

Subsequently, excess residual charges on the photosensitive member are removed by a charge eliminating member (not shown) as necessary. Thereafter, the charging member is uniformly charged again, and the next image formation is performed.
In the example of FIG. 9, the image forming elements are arranged in the order of Y (yellow), M (magenta), C (cyan), and K (black) from the upstream side to the downstream side in the transfer sheet conveyance direction. However, the order is not limited to this order, and the color order may be arbitrarily set. Further, when creating a black-only document, it is particularly effective to use the present invention to provide a mechanism that stops image forming elements other than black ((25Y), (25M), (25C)). .

(Image forming device)
The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photoconductor and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and the like. There are many shapes and the like of the process cartridge, but a general example is shown in FIG. The photoreceptor (101) is provided with a photosensitive layer including at least a charge generation layer and a charge transport layer on a conductive support, and the charge generation layer has a diffraction peak with a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm). (± 0.2 °) having a maximum diffraction peak at least 27.2 °, and further having major peaks at 9.4 °, 9.6 °, and 24.0 °, and the lowest angle side A primary peak having a peak at 7.3 ° and no peak between the peak at 7.3 ° and the peak at 9.4 °, and a peak at 26.3 °. It contains titanyl phthalocyanine crystals having an average particle size of 0.25 μm or less.

  As the charging member (102), a known charging member is used as described above. When a high-definition image is formed, the charging member is 30 V / μm or more (60 V / μm or less, preferably 50 V / μm or less). The following electric field strength is applied.

  As described above, a light source having a beam diameter of 50 μm or less that can be written at a resolution of 1200 dpi or more (preferably 241200 dpi or more) is used for the image exposure unit (103). In FIG. Reference numeral 105 denotes a transfer member, 106 denotes a transfer unit, 107 denotes a cleaning unit, and 108 denotes a charge eliminating unit.

  Hereinafter, the electrophotographic photosensitive member used in the image forming apparatus of the present invention will be described in detail.

  The electrophotographic photosensitive member used in the present invention is an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are formed on a conductive support, and CuKα rays (wavelength of 1. nm) are formed in the charge generation layer. As a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to 542 Å), it has a maximum diffraction peak at least 27.2 °, and further main peaks at 9.4 °, 9.6 °, and 24.0 ° And has a peak at 7.3 ° as the lowest angle diffraction peak, and no peak between the 7.3 ° peak and the 9.4 ° peak, and The primary particles having a peak at 26.3 ° contain titanyl phthalocyanine crystals having an average particle size of 0.25 μm or less.

  This crystal type is described in Patent Document 17, but by using this titanyl phthalocyanine crystal, a stable electrophotographic photosensitive member that does not cause deterioration in chargeability even after repeated use without losing high sensitivity is obtained. Can do.

  Patent Document 17 discloses a charge generating material used in the present invention, a photoconductor using the same, an electrophotographic apparatus, and the like. However, in the case of using a writing light source having a beam diameter of 50 μm or less for the purpose of high resolution, there are cases where the problem of unclearness of the small-diameter dot outline and the problem of carrier generation efficiency in a low electric field have occurred. Further, under the situation where the resolution is 1200 dpi or higher or 2400 dpi or higher, it is necessary to increase the electric field strength applied to the photosensitive member in order to make use of the writing resolution. However, when the electric field strength is high, there is a problem that soiling occurs. Such a phenomenon remarkably appears when used in an image forming apparatus that performs writing with higher resolution than the image forming apparatus described in the publication. Thus, in the past process (apparatus), not only the ability of the material described in the same publication is not sufficiently drawn out, but if the process conditions are not optimized, a side effect is produced.

  Further, Patent Document 1 does not describe the particle size and the technology for controlling the particle size, and the particle size is not optimized. In the present invention, a more optimal image forming apparatus is constructed by using a photoconductor containing a specific crystal type titanyl phthalocyanine having a controlled particle size and optimizing the process conditions of the image forming apparatus.

  As a method for synthesizing titanyl phthalocyanine crystals, a method in which titanium halide is not used as a raw material is well used as described in Patent Document 2. The biggest merit of this method is that the synthesized titanyl phthalocyanine crystal is free of halogenation. If the titanyl phthalocyanine crystal contains a halogenated titanyl phthalocyanine crystal as an impurity, the electrostatic characteristics of a photoreceptor using the crystal often have adverse effects such as a decrease in photosensitivity and a decrease in chargeability (see Non-Patent Document 1). ). In the present invention, halogenated free titanyl phthalocyanine crystals as described in Patent Document 17 are mainly used, and these materials are effectively used.

  First, a method for synthesizing a titanyl phthalocyanine crystal having a specific crystal type used in the present invention will be described.

  First, a method for synthesizing a crude product of titanyl phthalocyanine crystal will be described. Methods for synthesizing phthalocyanines have been known for a long time, and are described in Non-Patent Document 2, Patent Document 2, and the like. For example, as a first method, a mixture of phthalic anhydrides, metal or metal halide and urea is heated in the presence or absence of a high boiling point solvent. In this case, a catalyst such as ammonium molybdate is used in combination as necessary. As a second method, phthalonitriles and metal halides are heated in the presence or absence of a high boiling point solvent. This method is used for phthalocyanines that cannot be produced by the first method, such as aluminum phthalocyanines, indium phthalocyanines, oxovanadium phthalocyanines, oxotitanium phthalocyanines, zirconium phthalocyanines, and the like. The third method is to first react phthalic anhydride or phthalonitrile with ammonia to produce an intermediate such as 1,3-diiminoisoindoline, and then react with a metal halide in a high boiling solvent. It is a method to make it. The fourth method is a method in which phthalonitriles and a metal alkoxide are reacted in the presence of urea or the like. In particular, the fourth method does not cause chlorination (halogenation) to the benzene ring, and is a very useful method as a method for synthesizing an electrophotographic material, and is used extremely effectively in the present invention.

(Synthesis method of titanyl phthalocyanine crystal in the present invention)
Next, a method for synthesizing amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) will be described. In this method, phthalocyanines are dissolved in sulfuric acid, diluted with water and reprecipitated, and an acid paste method or an acid slurry method can be used.

  As a specific method, the above synthetic crude product is dissolved in 10 to 50 times the amount of concentrated sulfuric acid, and if necessary, insoluble matters are removed by filtration, etc., and this is sufficiently cooled relative to the amount of sulfuric acid. The resulting solution is slowly poured into 10 to 50 times the amount of water or ice water to reprecipitate titanyl phthalocyanine. The precipitated titanyl phthalocyanine is filtered, washed with ion-exchanged water and filtered, and this operation is sufficiently repeated until the filtrate becomes neutral. Finally, after washing with ion-exchanged water, filtration is performed to obtain a water paste having a solid concentration of about 5 to 15 wt%. What was produced in this way was the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) used in the present invention. In this case, the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) is at least 7.0 to 7 as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542Å) of CuKα. It preferably has a maximum diffraction peak at 5 °. In particular, the half width of the diffraction peak is more preferably 1 ° or more. Further, the average particle size of the primary particles is preferably 0.1 μm or less.

(Crystal conversion method)
Next, a crystal conversion method will be described. In the present invention, titanyl phthalocyanine crystals are synthesized from at least two crystal conversion steps.

  First, the first crystal conversion method will be described. In the first crystal conversion, the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) is used as a diffraction peak (± 0.2 °) of Bragg angle 2θ with respect to the characteristic X-ray of CuKα (wavelength 1.542 mm). It has a maximum diffraction peak at 2 °, a major peak at 9.4 °, 9.6 ° and 24.0 °, and a peak at 7.3 ° as the lowest diffraction peak. And a titanyl phthalocyanine crystal having no peak between the peak at 7.3 ° and the peak at 9.4 ° and having no peak at 26.3 °.

  As a specific method, the crystalline form is obtained by mixing and stirring the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) with an organic solvent in the presence of water without drying.

In this case, any organic solvent can be used as long as the desired crystal form can be obtained, but tetrahydrofuran, toluene, methylene chloride, carbon disulfide, orthodichlorobenzene, 1,1, Good results are obtained when one selected from 2-trichloroethane is selected. These organic solvents are preferably used alone, but two or more of these organic solvents may be mixed or used in combination with other solvents. The amount of the organic solvent used for crystal conversion is desirably 10 times or more, preferably 30 times or more, relative to the weight of amorphous titanyl phthalocyanine. This is because crystal transformation can be caused quickly and sufficiently, and impurities contained in the amorphous titanyl phthalocyanine can be sufficiently removed. The amorphous titanyl phthalocyanine used here is prepared by the acid paste method, but it is desirable to use one obtained by sufficiently washing sulfuric acid as described above. When crystal conversion is performed under conditions where sulfuric acid remains, sulfate ions remain in the crystal particles, and even if operations such as washing with water are performed, sulfate ions can be completely removed from the resulting crystals. I can't. When sulfate ions remain, preferable results cannot be obtained, such as a decrease in sensitivity and a decrease in chargeability of the photoreceptor. For example, Patent Document 3 (Comparative Example) describes a method in which titanyl phthalocyanine dissolved in sulfuric acid is added to an organic solvent together with ion-exchanged water to perform crystal conversion. At this time, a crystal similar to the X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in the present invention can be obtained. However, since the sulfate ion concentration in titanyl phthalocyanine is high and the light attenuation property (photosensitivity) is poor, It is not suitable for the method for producing titanyl phthalocyanine of the invention. The above crystal conversion method is a crystal conversion method according to Patent Document 17. On the other hand, in the charge generating material contained in the photoreceptor used in the electrophotographic apparatus of the present invention, the effect is achieved by making the particle size of the titanyl phthalocyanine crystal finer (0.25 μm or less). The following describes a synthetic approach for titanyl phthalocyanine having a small particle size.

(Particle size and crystal form of titanyl phthalocyanine crystal in the present invention)
According to observations by the present inventors, the above-mentioned amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) has a primary particle size of 0.1 μm or less (most of which is about 0.01 to 0.05 μm). (See FIG. 11), it was found that the crystal form was converted as the crystal grew. Usually, in this type of crystal conversion, a sufficient crystal conversion time is ensured due to fear of remaining of the raw material, and after the crystal conversion is sufficiently performed, filtration is performed to obtain a titanyl phthalocyanine crystal having a desired crystal type. Have gained. For this reason, even though a raw material having sufficiently small primary particles is used as the raw material, a crystal having a large primary particle (approximately 0.3 to 0.5 μm) is obtained in the crystal after crystal conversion (see FIG. 12).

  The scale bars in the figure are all 0.2 μm.

  In order to disperse the titanyl phthalocyanine crystal produced as shown in FIG. 12, in order to reduce the particle size after dispersion (0.25 μm or less), dispersion is performed by giving a strong share, and further necessary. In response to this, dispersion is performed by giving strong energy to pulverize the primary particles. As a result, as described above, there is a possibility that a part of the particles may be transferred to a crystal type which is not a desired crystal type.

  In this regard, by controlling the primary particle size of the titanyl phthalocyanine crystal from the synthesis stage, it is possible to obtain a crystal having a small size, which can solve this problem, and is effectively used in the present invention. Specifically, the range in which crystal growth hardly occurs during crystal conversion (the range in which the size of the amorphous titanyl phthalocyanine particles observed in FIG. 11 is insignificantly small after crystal conversion, approximately 0.25 μm or less. ) Is to obtain a titanyl phthalocyanine crystal having a primary particle size as small as possible by determining when the crystal conversion is completed. The particle size after crystal conversion increases in proportion to the crystal conversion time. For this reason, as described above, it is important to increase the efficiency of crystal conversion and complete it in a short time. There are several important points for this.

  The first point is to select an appropriate crystal conversion solvent as described above and increase the crystal conversion efficiency. Another point is to vigorously stir the solvent and the titanyl phthalocyanine aqueous paste (the raw material prepared as described above) sufficiently in order to complete the crystal conversion in a short time. Specifically, crystal conversion in a short time is realized by a method such as stirring using a propeller having a very strong stirring force, or using a strong stirring (dispersing) means such as a homogenizer (homomixer). Under these conditions, it is possible to obtain a titanyl phthalocyanine crystal in a state where the raw material does not remain, crystal conversion is sufficiently performed, and crystal growth does not occur.

  FIG. 13 is a TEM image of a titanyl phthalocyanine crystal subjected to crystal conversion in a short time in consideration of the above two points. The scale bar in the figure is 0.2 μm.

  In addition, since the crystal grain size and the crystal conversion time are in a proportional relationship as described above, a method of immediately stopping the reaction when a predetermined reaction (crystal conversion) is completed is also an effective means. One example of this means is to immediately add a large amount of a solvent in which crystal conversion hardly occurs after crystal conversion as described above. Examples of the solvent that hardly causes crystal transformation include alcohol-based and ester-based solvents. Crystal conversion can be stopped by adding about 10 times these solvents to the crystal conversion solvent.

  The smaller the primary particle size produced in this way, the better the results for the problem of the photoreceptor, but the next step for pigment preparation (pigment filtration step), the dispersion stability in the dispersion liquid When considered, other problems can occur if it is too small. That is, when the primary particles are very fine, the filtration time becomes very long in the step of filtering the primary particles. In addition, when the primary particles are too fine, the surface area of the pigment particles in the dispersion increases, and the possibility of reaggregation of the particles increases. Therefore, the suitable particle size of the pigment particles is in the range of about 0.05 μm to 0.2 μm.

  FIG. 13 shows a TEM image of a titanyl phthalocyanine crystal when crystal conversion is performed in a short time. Unlike the case of FIG. 12, the particle size is small and almost uniform, and the coarse particles observed in FIG. 12 are not recognized at all.

  As shown in FIG. 13, when dispersing titanyl phthalocyanine crystals prepared in a state where the primary particles are small, the particle size after dispersion is made small (0.25 μm or less, more preferably 0.2 μm or less). For this purpose, it is possible to disperse by giving a share sufficient to loosen the secondary particles formed by aggregation of the primary particles. Since energy is not applied more than necessary, as described above, it is possible to easily produce a dispersion having a fine particle size distribution without transferring some of the particles to a desired crystal type.

  The particle size referred to here is a volume average particle size, measured by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba Seisakusho), and a particle size corresponding to 50% of the cumulative distribution (Media type). Is calculated as follows. However, this method may not be able to detect a very small amount of coarse particles. Therefore, in order to obtain more details, it is important to observe the titanyl phthalocyanine crystal powder or dispersion directly with an electron microscope and determine its size. It is.

  As a result of further examination of the microscopic defects by further observation of the dispersion, the above phenomenon is understood as follows. Normally, in the method of measuring the average particle size, it can be detected when extremely large particles are present in a few percent or more, but when the amount becomes as small as 1% or less of the whole, it is below the detection limit. turn into. As a result, the presence of coarse particles cannot be detected only by measuring the average particle size, and it is difficult to interpret the above-described minute defects.

  FIGS. 14 and 15 show photographs observing the state of two types of dispersions in which only the dispersion time is changed while fixing the dispersion conditions. The dispersion time in FIGS. 14 and 15 is shorter in FIG. 14, and in FIG. 14, it is observed that coarse particles remain. The black particles in FIG. 14 are coarse particles.

  The average particle size and particle size distribution of these two types of dispersions were measured according to a known method using a commercially available particle size distribution measuring device (manufactured by Horiba: ultracentrifugal automatic particle size distribution measuring device, CAPA700). The result is shown in FIG. “A” in FIG. 16 corresponds to the dispersion shown in FIG. 14, and “B” corresponds to the dispersion shown in FIG. When both are compared, there is almost no difference in the particle size distribution. In addition, the average particle diameter values of the two are “A” of 0.29 μm and “B” of 0.28 μm, and taking into account measurement errors, there is no difference between the two. Therefore, it is understood that the remaining of a very small amount of coarse particles cannot be detected only by the definition of the known average particle size (particle size), and it is not possible to cope with the recent high-resolution negative / positive development. The presence of such a minute amount of coarse particles can be recognized for the first time by observing the coating solution at the microscope level.

  It is a figure which shows an average particle diameter and a particle size distribution about the dispersion liquid of FIG.

  In response to such a fact, it is an effective means to produce as small primary particles as possible during the first crystal conversion. For this reason, an effective method is to select an appropriate crystal conversion solvent as described above, and to increase the crystal conversion efficiency and complete the crystal conversion in a short time, while using a solvent and a titanyl phthalocyanine water paste (described above). Such a raw material) is vigorously stirred to bring it into sufficient contact.

  By adopting such a crystal conversion method, a titanyl phthalocyanine crystal having a small primary particle size (0.25 μm or less, more preferably 0.2 μm or less) can be obtained. In addition to the technique described in Patent Document 17, it is an important means in the present invention to use the above-described technique (crystal conversion method for obtaining fine titanyl phthalocyanine crystals) as necessary.

  Subsequently, the crystallized titanyl phthalocyanine crystal is immediately filtered to be separated from the crystal conversion solvent. This filtration is performed by using a filter of an appropriate size. In this case, it is most appropriate to use vacuum filtration.

  Thereafter, the separated titanyl phthalocyanine crystal is heat-dried as necessary. Any known dryer can be used for heat drying, but a blower dryer is preferred when the drying is performed under atmospheric pressure. Furthermore, drying at a reduced pressure is a very effective means in order to increase the drying speed and to exhibit the effects of the present invention more remarkably. In particular, this is an effective means for a material that decomposes at a high temperature or changes its crystal form. In particular, it is effective to dry in a state where the degree of vacuum is higher than 10 mmHg.

The thus obtained titanyl phthalocyanine crystal having a specific crystal type is extremely useful as a charge generating material for an electrophotographic photoreceptor. However, as described above, the crystal form is unstable, and there is a drawback that the crystal form is easily transferred when a dispersion is prepared. However, by synthesizing primary particles into infinitely small particles as in the present invention, a dispersion with a small average particle diameter can be prepared without giving an excessive share during the preparation of the dispersion, and the crystal type is also extremely high. It can be produced stably (without changing the synthesized crystal form).
Next, the second crystal conversion method will be described. The second crystal conversion is a step of further crystal conversion using the titanyl phthalocyanine crystal (dry powder) prepared by the first crystal conversion. Specific methods include two methods.

One is a method of treating the previously prepared titanyl phthalocyanine crystal in an organic solvent. As the organic solvent used, any solvent can be used as long as it can convert the crystal form having the maximum diffraction peak at 27.2 ° to the crystal form having the maximum diffraction peak at 26.3 °. Aromatic hydrocarbons such as xylene, ketones such as acetone and 2-butanone, halogenated hydrocarbons such as methylene chloride and chloroform, and cyclic ethers such as tetrahydrofuran are preferably used.
Regarding the treatment of the organic solvent, the titanyl phthalocyanine crystal may be simply immersed in the organic solvent as it is, but the treatment time can be shortened by using auxiliary means such as stirring and ultrasonic application together. ,It is valid. After the treatment with an organic solvent, the target titanyl phthalocyanine crystal can be obtained by separating by filtration and drying again.

  As another method, a crystal transformation is performed by applying a mechanical shearing force to the previously prepared titanyl phthalocyanine crystal. At this time, an organic solvent may be used in combination, but it is desirable to perform the treatment in a dry state without using it together. As a method to be used, dry milling using a ball mill, attritor, vibration mill, kneader, or the like, or simply dry milling using a mixer is also effective. Moreover, you may use inorganic salts, such as salt, as an adjuvant in the case of dry milling. When an auxiliary agent is used, a washing step for removing inorganic salts is necessary after the crystal conversion treatment. Thus, the target titanyl phthalocyanine crystal can be obtained.

  Whichever method is used, it is important that the peak intensity at 26.3 ° is in the range of 0.1 to 5% with respect to the peak intensity at the maximum diffraction peak of 27.2 °. If it is less than 0.1%, the effects of the present invention, such as charging stability and environmental stability, cannot be obtained. On the other hand, when it is larger than 5%, a side effect of increasing the residual potential is produced. Therefore, it is important that the above range. The peak intensity of 26.3 ° is determined by the treatment time in the solvent or the treatment time giving mechanical shearing force, but the state of the raw material used (the titanyl phthalocyanine crystal produced by the first crystal conversion) (for example, It is desirable to determine the treatment time through preliminary experiments because it varies depending on the size and hardness of the powder.

(Method for creating dispersion)
Next, a method for preparing the dispersion will be described.

  A general method is used for the preparation of the dispersion, and the titanyl phthalocyanine crystal is dispersed in a suitable solvent together with a binder resin as necessary by using a ball mill, an attritor, a sand mill, a bead mill, an ultrasonic wave, or the like. can get. At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.

  As already mentioned, the titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm) is It is known that a crystal transition easily occurs to another crystal type due to a stress such as a dynamic share. This tendency does not change in the titanyl phthalocyanine crystal used in the present invention. In other words, in order to produce a dispersion containing fine particles, it is necessary to devise a dispersion method, but the stability of the crystal form and the micronization tend to be in a trade-off relationship. Although there are methods for avoiding this by optimizing the dispersion conditions, all of them make the manufacturing conditions extremely narrow, and a simpler method is desired. In order to solve this problem, the following method is also an effective means.

  That is, it is a method in which a dispersion liquid in which the particles are made as fine as possible is prepared as long as crystal transition does not occur, and then filtered through an appropriate filter. This method is a very effective means in that it can remove even a trace amount of coarse particles that cannot be visually observed (or cannot be detected by particle size measurement) and that the particle size distribution is uniform. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore size of 3 μm or less, more preferably 1 μm or less to prepare a dispersion. Also by this method, a dispersion containing only titanyl phthalocyanine crystals having a small particle size (0.25 μm or less, more preferably 0.2 μm or less) can be produced, and a photoconductor using the dispersion is mounted on an image forming apparatus. By using it, the effect of the present application becomes even more remarkable.

  The filter for filtering the dispersion varies depending on the size of coarse particles to be removed, but according to the study by the present inventors, a photosensitive member used in an electrophotographic apparatus requiring a resolution of about 600 dpi is at least 3 μm. The presence of the above coarse particles affects the image. Therefore, a filter with an effective pore size of 3 μm or less should be used. More preferably, a filter having an effective pore size of 1 μm or less is used. By performing such a filtering process, unnecessary coarse particles can be removed, and a dispersion having a narrow particle size distribution and no coarse particles can be produced.

  As for the effective pore size, finer particles are effective in removing coarse particles. However, if they are too fine, necessary pigment particles themselves are also filtered, so an appropriate size is selected. Also, if the effective diameter is too small, (1) it takes time to filter, (2) the filter is clogged, (3) too much load is applied when using a pump, etc. Cause problems. As a matter of course, the material of the filter used here is one that is resistant to the solvent used in the dispersion to be filtered.

  During filtration, if the amount of coarse particles in the dispersion to be filtered is too large, the amount of pigment to be removed increases, and the solid content concentration of the dispersion after filtration changes, which is not preferable. Therefore, an appropriate particle size distribution (particle size, standard deviation) exists when performing filtration. As in the present invention, there is no loss of pigment due to filtration, filter clogging, etc., and in order to perform filtration efficiently, the volume average particle size of the dispersion before filtration is 0.3 μm or less, and its standard deviation is It is desirable to disperse to 0.2 μm or less.

  By adding such an operation of filtering the dispersion, coarse particles can be removed, and as a result, background contamination generated on the photoconductor using the dispersion can be reduced. As described above, the finer the filter, the greater the effect, but the pigment particles themselves may be filtered. In such a case, a very large effect can be obtained by using in combination with the above-described technology for refining and synthesizing the primary titanyl phthalocyanine particles.

  That is, (i) by synthesizing and using refined titanyl phthalocyanine, the dispersion time can be shortened and the dispersion stress can be reduced, and the possibility of crystal transition in dispersion is reduced. (Ii) Since the size of the coarse particles remaining after dispersion is smaller than that in the case where the particles are not refined, a smaller filter can be used, and the effect of removing the coarse particles becomes more reliable. In addition, the amount of titanyl phthalocyanine particles to be removed is reduced, and there is little change in the composition of the dispersion before and after filtration, which enables stable production. (Iii) As a result, the manufactured photoreceptor is stably manufactured with high resistance to soiling.

  The intensity ratio of the 26.3 ° peak intensity to the 27.2 ° peak intensity in the titanyl phthalocyanine crystal of the present invention will be described.

An X-ray diffraction spectrum is measured with a general X-ray diffractometer in a powder state of the titanyl phthalocyanine crystal to be used. Baseline correction is performed on the obtained spectrum, and then a peak intensity of 26.3 ± 0.2 ° and a peak intensity of 27.2 ± 0.2 ° are obtained. Using the value, the value obtained by dividing the peak intensity of 26.3 ± 0.2 ° by the peak intensity of 27.2 ± 0.2 ° is the peak intensity ratio in the present invention.
Peak intensity ratio (%) =
26.3 ± 0.2 ° peak intensity / 27.2 ± 0.2 ° peak intensity × 100
When the peak intensity ratio is 1% or less, it may be difficult to correct the baseline in measurement over a wide range. In that case, the intensity ratio can be obtained more accurately by narrowing the measurement range (for example, measuring within a range of 25 to 30 °) and performing remeasurement.

(Electrophotographic photoreceptor)
Next, the electrophotographic photosensitive member used in the present invention will be described in detail with reference to the drawings.

  FIG. 17 is a cross-sectional view showing a structural example of the electrophotographic photosensitive member used in the present invention. On the conductive support (31), a titanyl phthalocyanine crystal (charge generating material) having the specific particle size and the specific crystal type is shown. ) As a main component and a charge transport layer (37) whose main component is a charge transport material are stacked.

  FIG. 18 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member used in the present invention, and a titanyl phthalocyanine crystal having the specific particle size and the specific particle size on the conductive support (31). A charge generation layer (35) mainly composed of (charge generation material) and a charge transport layer (37) mainly composed of a charge transport material are laminated, and a protective layer (39) is further formed on the charge transport layer. It has a configuration that is provided.

As the conductive support (31), a material having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium by vapor deposition or sputtering, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel plates, etc. and methods such as extrusion and drawing After forming the tube, it is possible to use a tube subjected to surface treatment such as cutting, superfinishing or polishing. Moreover, the endless nickel belt and the endless stainless steel belt disclosed in Patent Document 4 can also be used as the conductive support (31).

  Of these, a cylindrical support made of aluminum, which can be easily subjected to the anodic oxide film treatment, can be most preferably used. As used herein, aluminum includes either pure aluminum or aluminum alloy. Specifically, JIS 1000, 3000, and 6000 series aluminum or aluminum alloy is most suitable. Anodized films can be obtained by anodizing various metals and various alloys in an electrolyte solution, but the most suitable for the photoreceptor used in the present invention is aluminum or an aluminum alloy in an electrolyte solution. It is a film called anodized. In particular, it is excellent in that it can prevent point defects (black spots, background stains) that occur when used in reversal development (negative / positive development).

The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example, sulfuric acid concentration: 10 to 20%, bath temperature: 5 to 25 ° C., current density: 1 to 4 A / dm ² , electrolytic voltage: 5 to 30 V, treatment time: treatment in the range of about 5 to 60 minutes However, the present invention is not limited to this. Since the anodic oxide film produced in this way is porous and has high insulating properties, the surface is very unstable. For this reason, it changes with time after fabrication, and the physical property value of the anodized film is likely to change. In order to avoid this, it is desirable to further seal the anodized film. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Among these, the method of immersing in the aqueous solution containing nickel acetate is the most preferable. Subsequent to the sealing treatment, the anodic oxide film is washed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If the metal salt remains excessively on the surface of the support (anodized film), not only will it adversely affect the quality of the coating film formed on the surface, but generally low resistance components will remain. It will also cause the occurrence of. Washing may be performed only once with pure water, but usually multi-stage cleaning is performed. At this time, it is preferable that the final cleaning liquid is as clean (deionized) as possible. Further, in one of the multi-stage cleaning processes, it is desirable to perform physical rubbing cleaning with a contact member. The film thickness of the anodized film formed as described above is preferably about 5 to 15 μm. If it is too thin, the barrier effect as an anodic oxide film is not sufficient, and if it is too thick, the time constant as an electrode becomes too large, resulting in the generation of residual potential and the response of the photoreceptor. There is a case.

  In addition to the above, a conductive powder dispersed in a suitable binder resin and coated on the support can be used as the conductive support (31) of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide such as conductive tin oxide and indium tin oxide (ITO). Examples include powder. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, polytetrafluoroethylene fluororesin on a suitable cylindrical substrate. Those provided with a conductive layer can be used favorably as the conductive support (31) of the present invention.

  Next, the photosensitive layer will be described. As described above, as the photosensitive layer, a laminated type composed of the charge generation layer (35) and the charge transport layer (37) exhibits excellent characteristics in sensitivity and durability, and is used favorably.

The charge generation layer (35) has, as a charge generation material, a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα characteristic X-rays (wavelength 1.542 mm). The crystal form). In particular, among the crystal types, there are further main peaks at 9.4 °, 9.6 °, 24.0 °, and the lowest diffraction angle has a peak at 7.3 °, In addition, there is no peak between the peak at 7.3 ° and the peak at 9.4 °, and the average particle size of primary particles having a peak at 26.3 ° is not more than 0.25 μm (preferably 0 .2 μm or less) titanyl phthalocyanine crystals are used favorably.

  The charge generation layer (35) is dispersed, as necessary, together with a binder resin in a suitable solvent using a ball mill, an attritor, a sand mill, an ultrasonic wave, etc., and this is applied onto a conductive support. It is formed by drying.

  The binder resin used for the charge generation layer (35) as required may be polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicon resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly -N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone Etc. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material.

  Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The thickness of the charge generation layer 35 is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

  The charge transport layer (37) can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

  Charge transport materials include hole transport materials and electron transport materials.

  Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

  Examples of the hole transport material include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned. These charge transport materials may be used alone or in combination of two or more.

  Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.

  The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm.

  As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. Among these, it is desirable to use a non-halogen solvent for the purpose of reducing the environmental load. Specifically, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof are preferably used.

  In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. The charge transport layer composed of these polymer charge transport materials is excellent in wear resistance. As the polymer charge transport material, known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the formulas (I) to (X) are favorably used, and these are exemplified below and specific examples are shown.

(I) In the formula, R1, R2, and R3 are each independently a substituted or unsubstituted alkyl group or a halogen atom, R4 is a hydrogen atom or a substituted or unsubstituted alkyl group, and R5 and R6 are substituted or unsubstituted. Aryl group, o, p and q are each independently an integer of 0 to 4, k and j represent a composition, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n represents the number of repeating units. It is an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula. In the formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

R101 and R102 each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or

(A represents an integer of 1 to 20, b represents an integer of 1 to 2000, and R103 and R104 represent a substituted or unsubstituted alkyl group or aryl group). Here, R101 and R102, and R103 and R104 may be the same or different. )

(II) In the formula, R7 and R8 represent substituted or unsubstituted aryl groups, and Ar1, Ar2 and Ar3 represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (II), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(III) Formula

In the formula, R9 and R10 represent substituted or unsubstituted aryl groups, and Ar4, Ar5 and Ar6 represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (III), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(IV) Formula

In the formula, R11 and R12 are substituted or unsubstituted aryl groups, Ar7, Ar8, and Ar9 are the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j and n are the same as in the case of the formula (I). In the formula (IV), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(V) Formula

In the formula, R13 and R14 are substituted or unsubstituted aryl groups, Ar10, Ar11 and Ar12 are the same or different arylene groups, and X1 and X2 are substituted or unsubstituted ethylene groups, or substituted or unsubstituted vinylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (V), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(VI) Formula

In the formula, R15, R16, R17 and R18 are substituted or unsubstituted aryl groups, Ar13, Ar14, Ar15 and Ar16 are the same or different arylene groups, Y1, Y2 and Y3 are single bonds, substituted or unsubstituted alkylene groups, It represents a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, which may be the same or different. X, k, j and n are the same as in the case of the formula (VI). In the formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(VII) Formula

In the formula, R19 and R20 each represent a hydrogen atom or a substituted or unsubstituted aryl group, and R19 and R20 may form a ring. Ar17, Ar18 and Ar19 represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (VII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(VIII) Formula

In the formula, R21 represents a substituted or unsubstituted aryl group, Ar20, Ar21, Ar22, Ar23. Represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (VIII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(IX) Formula

In the formula, R22, R23, R24, and R25 represent substituted or unsubstituted aryl groups, and Ar24, Ar25, Ar26, Ar27, and Ar28 represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (IX), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.
(X) Formula

In the formula, R26 and R27 represent substituted or unsubstituted aryl groups, and Ar29, Ar30, and Ar31 represent the same or different arylene groups. X, k, j and n are the same as in the case of the formula (I). In the formula (X), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

  Further, as the polymer charge transport material used in the charge transport layer, in addition to the polymer charge transport material described above, in the state of the monomer or oligomer having an electron donating group at the time of film formation of the charge transport layer, Polymers finally having a two-dimensional or three-dimensional crosslinked structure are also included by carrying out a curing reaction or a crosslinking reaction.

  A charge transport layer composed of a polymer having these electron donating groups or a polymer having a crosslinked structure is excellent in wear resistance. Usually, in the electrophotographic process, since the charging potential (unexposed portion potential) is constant, when the surface layer of the photoconductor is worn by repeated use, the electric field strength applied to the photoconductor is increased accordingly. As the electric field strength increases, the occurrence frequency of scumming increases. Therefore, the high wear resistance of the photosensitive member is advantageous for scumming. The charge transport layer composed of a polymer having these electron donating groups is a polymer compound, so it has excellent film-forming properties and has a charge transport site compared to a charge transport layer composed of a low molecular weight dispersed polymer. It can be configured with high density and has excellent charge transport capability. For this reason, a photoreceptor having a charge transport layer using a polymer charge transport material can be expected to have a high response speed.

  As other polymers having an electron donating group, known monomer copolymers, block polymers, graft polymers, star polymers, and for example, Patent Document 5, Patent Document 6, Patent Document 7, etc. It is also possible to use a crosslinked polymer having an electron donating group as disclosed.

  In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer (37). As the plasticizer, those used as a plasticizer for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is suitable.

  In the electrophotographic photoreceptor of the present invention, an intermediate layer can be provided between the conductive support (31) and the photosensitive layer. In general, the intermediate layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on the resin, it is desirable that the resin be a resin having a high solvent resistance with respect to a general organic solvent. . Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, in order to prevent moire and reduce the residual potential, the intermediate layer may contain fine powder pigments of metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like.

  These intermediate layers can be formed by using an appropriate solvent and coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the intermediate layer of the present invention. In addition, for the intermediate layer of the present invention, a method in which Al2O3 is provided by anodic oxidation, an organic material such as polyparaxylylene (parylene), or an inorganic material such as SiO2, SnO2, TiO2, ITO, CeO2 is prepared by a vacuum thin film forming method Those provided in can also be used satisfactorily. In addition, known ones can be used. The thickness of the intermediate layer is suitably from 0 to 5 μm.

  In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. In recent years, computers have been used on a daily basis, and there has been a demand for downsizing of the apparatus as well as high-speed output by a printer. Therefore, by providing a protective layer and improving the durability, it is possible to use the photosensitive member of the present invention with high sensitivity and no abnormal defects.

  In the photoreceptor of the present invention, a protective layer (39) may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. Materials used for the protective layer (39) include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone. , Polybutylene, polybutylene terephthalate, polycarbonate, polyarylate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane , Resins such as polyvinyl chloride, polyvinylidene chloride, and epoxy resin. Of these, polycarbonate or polyarylate can be most preferably used.

  In addition to the protective layer, fluororesins such as polytetrafluoroethylene, silicone resins, and inorganic fillers such as titanium oxide, tin oxide, potassium titanate, and silica for the purpose of improving wear resistance (inorganic pigments) ), Or an organic filler (organic pigment) dispersed therein can be added.

  Among the filler materials used for the protective layer of the photoreceptor, examples of the organic filler material include fluorine resin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder, and the like. Metals such as copper, tin, aluminum and indium, silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, tin doped indium oxide and other metals Inorganic materials such as oxide and potassium titanate can be mentioned. In particular, it is advantageous to use an inorganic material among them from the viewpoint of the hardness of the filler. In particular, silica, titanium oxide, and alumina can be used effectively.

  The filler concentration in the protective layer varies depending on the type of filler used and also on the electrophotographic process conditions using the photoconductor, but the ratio of filler to the total solid content on the outermost layer side of the protective layer is preferably 5% by weight or more, preferably 10% by weight or more and 50% by weight or less, preferably about 30% by weight or less is good.

  Moreover, the volume average particle diameter of the filler to be used is preferably in the range of 0.1 μm to 2 μm, and preferably in the range of 0.3 μm to 1 μm. In this case, if the average particle size is too small, the wear resistance is not sufficiently exhibited, and if it is too large, the surface property of the coating film is deteriorated or the coating film itself cannot be formed.

  The average particle size of the filler in the present invention is a volume average particle size unless otherwise specified, and is measured by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba). It is calculated as a particle size (Median system) corresponding to 50%. In addition, it is important that the standard deviation of each particle measured simultaneously is 1 μm or less. When the standard deviation value is 1 μm or more, the particle size distribution is too wide, and the effects of the present invention may not be obtained remarkably.

Further, the pH of the filler used in the present invention greatly affects the resolution and the dispersibility of the filler. One possible reason is that hydrochloric acid or the like used during production remains in the filler, particularly the metal oxide. When the residual amount of hydrochloric acid or the like is large, image blurring occurs, and the dispersibility of the filler may be affected depending on the residual amount.

Another reason is due to the difference in chargeability on the surface of the filler, particularly the metal oxide. Usually, particles dispersed in a liquid are charged positively or negatively, and ions having opposite charges gather to try to keep it electrically neutral, and an electric double layer is formed there. The dispersed state of the particles is stabilized. The potential (zeta potential) gradually decreases with increasing distance from the particle, and the potential in a region that is sufficiently away from the particle and electrically neutral is zero. Therefore, the stability increases as the repulsive force of the particles increases due to an increase in the absolute value of the zeta potential, and the particles tend to aggregate and become unstable as they approach zero. On the other hand, the zeta potential varies greatly depending on the pH value of the system (vehicle), and at a certain pH value, the potential becomes zero and has an isoelectric point. Therefore, the dispersion system is stabilized by increasing the absolute value of the zeta potential away from the isoelectric point of the system (vehicle) as much as possible.

  In the configuration of the present invention, the filler having a pH at the isoelectric point of at least 5 is preferably from the viewpoint of image blur suppression, and the more basic the filler, the higher the effect. confirmed. A filler having a basic pH with a high pH at the isoelectric point has a higher zeta potential when the system (vehicle) is more acidic, thereby improving dispersibility and its stability.

  Here, the pH of the filler in the present invention is the pH value at the isoelectric point from the zeta potential. At this time, the zeta potential was measured with a laser zeta potentiometer manufactured by Otsuka Electronics Co., Ltd.

Further, as a filler that is less likely to cause image blur, a filler having high electrical insulation (specific resistance is 10 ¹⁰ Ω · cm or more) is preferable, and a filler having a pH of 5 or more or a dielectric constant of the filler of 5 or more. Can be used particularly effectively. In addition, a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more can be used alone, or two or more fillers having a pH of 5 or less and a filler having a pH of 5 or more can be mixed. It is also possible to use a mixture of two or more fillers having a dielectric constant of 5 or less and a filler having a dielectric constant of 5 or more. Among these fillers, α-type alumina, which has high insulation properties, high thermal stability, and high wear resistance, is a hexagonal close-packed structure, from the viewpoint of suppressing image blur and improving wear resistance. It is particularly useful.

The specific resistance of the filler used in the present invention is defined as follows. Since the specific resistance value of a powder such as a filler varies depending on the filling rate, it is necessary to measure under certain conditions. In the present invention, the specific resistance value of the filler was measured using an apparatus having the same configuration as the measurement apparatus shown in Patent Document 18 (FIG. 1) and Patent Document 9 (FIG. 1), and this value was used. . The electrode area of the measuring device is 4.0 cm ² . Prior to measurement, a load of 4 kg is applied to one electrode for 1 minute, and the sample amount is adjusted so that the distance between the electrodes is 4 mm. At the time of measurement, the measurement is performed with the weight of the upper electrode (1 kg) loaded, and the applied voltage is measured at 100V. The area of 10 ⁶ Ω · cm or more was measured with a HIGH RESISTER METER (Yokogawa Hewlett Packard), and the area below it was measured with a digital multimeter (Fluke). In the present invention, the specific resistance value obtained by this measurement is defined as the specific resistance value.

  The dielectric constant of the filler was measured as follows. A cell similar to the measurement of the specific resistance described above was used, and after applying a load, the capacitance was measured, and the dielectric constant was determined therefrom. For the measurement of the capacitance, a dielectric loss measuring device (Ando Electric) was used.

Further, these fillers can be surface-treated with at least one kind of surface treatment agent, and it is preferable from the viewpoint of dispersibility of the fillers. Decreasing the dispersibility of the filler not only increases the residual potential, but also decreases the transparency of the coating film, causes defects in the coating film, and decreases the wear resistance. It can develop into a big problem to hinder. As the surface treatment agent, all conventionally used surface treatment agents can be used, but a surface treatment agent capable of maintaining the insulating properties of the filler is preferable. For example, titanate coupling agents, aluminum coupling agents, zircoaluminate coupling agents, higher fatty acids, etc., or a mixture thereof with a silane coupling agent from the viewpoint of improving filler dispersibility and preventing image blurring It is more preferable to perform the treatment, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , silicone, aluminum stearate or the like, or a combination thereof. The treatment with the silane coupling agent is strongly influenced by image blur, but the influence may be suppressed by performing a mixing treatment of the surface treatment agent and the silane coupling agent. The surface treatment amount varies depending on the average primary particle size of the filler used, but is preferably 3 to 30 wt%, more preferably 5 to 20 wt%, based on the total solid content constituting the protective layer. If the surface treatment amount is less than this, the filler dispersion effect cannot be obtained, and if it is too much, the residual potential is significantly increased. These filler materials may be used alone or in combination of two or more. The surface treatment amount of the filler is defined by the weight ratio of the surface treatment agent to be used with respect to the filler amount as described above.

  These filler materials can be dispersed by using an appropriate disperser. Further, from the viewpoint of the transmittance of the protective layer, it is preferable that the filler used is dispersed to the primary particle level and has less aggregates.

  In order to reduce the residual potential and improve the response, the protective layer (39) may contain a charge transport material, and the materials described in the description of the charge transport layer can be used. When a low molecular charge transport material is used as the charge transport material, a concentration gradient in the protective layer may be provided. In order to improve wear resistance, it is an effective means to reduce the concentration of the surface side. The concentration here means the ratio of the weight of the low-molecular charge transporting substance to the total weight of all the materials constituting the protective layer, and the concentration gradient means that the layer has a lower concentration on the surface side at the above weight ratio. It shows that it is provided. The use of a polymer charge transport material is very advantageous in terms of enhancing the durability of the photoreceptor.

  As a method for forming the protective layer, a normal coating method is employed. In addition, about 0.1-10 micrometers is suitable for the thickness of a protective layer. In addition to the above, a known material such as a-C or a-SiC formed by a vacuum thin film forming method can be used as the protective layer.

  In addition, the polymer charge transport material described in the section of the charge transport layer can be used as the binder resin for the protective layer. As the effect when this is used, the effect of improving the wear resistance and the high-speed charge transport can be obtained as described in the section of the charge transport layer.

  Moreover, the protective layer which consists of a crosslinked structure is also used effectively as a binder structure of a protective layer. Regarding the formation of the cross-linked structure, a reactive monomer having a plurality of cross-linkable functional groups in one molecule is used to cause a cross-linking reaction using light or heat energy to form a three-dimensional network structure. This network structure functions as a binder resin and exhibits high wear resistance.

Moreover, it is a very effective means to use a monomer having a charge transporting ability in whole or in part as the reactive monomer. By using such a monomer, a charge transport site is formed in the network structure, and the function as a protective layer can be sufficiently expressed. A reactive monomer having a triarylamine structure is effectively used as the monomer having charge transporting ability.
The charge transport layer having such a network structure has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and may be cracked if it is too thick. In such a case, the protective layer may be a laminated structure, a low molecular dispersion polymer protective layer may be used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure may be formed on the upper layer (surface side). good.

  As described above, the use of a polymer charge transport material for the photosensitive layer (charge transport layer) or the provision of a protective layer on the surface of the photoreceptor increases the durability (wear resistance) of each photoreceptor. In addition, when used in a tandem type full-color image forming apparatus as described later, a new effect not found in a monochrome image forming apparatus is also produced.

  In the case of a full-color image, various types of images are input, but on the contrary, a typical image may also be input. For example, a check in a Japanese document or the like. The marking or the like is usually placed at the end of the image area, and the colors used are also limited. In a state in which a random image is always written, image writing, development, and transfer are performed on the photoconductor in the image forming element on average. When many image formations are repeated or only a specific image forming element is used, the durability balance is lost. When a photoreceptor having low surface durability (physical / chemical / mechanical) is used in such a state, this difference becomes significant, and an image problem is likely to occur. On the other hand, when the photoconductor is made highly durable, the amount of such local change is small, and as a result, it becomes difficult to appear as a defect on the image, so that high durability is achieved and the stability of the output image is improved. This is very effective.

  Hereinafter, although an example is given and the present invention is explained, the present invention is not restricted by an example. All parts are parts by weight.

First, a synthesis example of a charge generation material (titanyl phthalocyanine crystal) will be described.
(Comparative Synthesis Example 1)
A pigment was produced according to Patent Document 1. That is, 29.2 g of 1,3-diiminoisoindoline and 200 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After completion of the reaction, the mixture was allowed to cool at room temperature, and the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, and further washed several times with hot water at 80 ° C. Drying gave crude titanyl phthalocyanine. Dissolve the crude titanyl phthalocyanine in 20 times the amount of concentrated sulfuric acid, add dropwise to 100 times the amount of ice water with stirring, filter the precipitated crystals, and then repeat washing with water until the washing solution becomes neutral. (Water paste) was obtained. 2 g of the obtained wet cake (water paste) was added to 20 g of tetrahydrofuran and stirred for 4 hours, followed by filtration and drying of the residue to obtain a titanyl phthalocyanine powder.

Further, 30 g of this titanyl phthalocyanine crystal was immersed in 300 g of tetrahydrofuran, and a second crystal conversion was performed. After leaving it immersed for 12 hours, it was separated by filtration and dried under reduced pressure under the same conditions as above to obtain a titanyl phthalocyanine crystal used in the present invention. This is designated as Pigment 1. (Referred to as pigment 1).
(Synthesis Example 1)
In accordance with the method of Comparative Synthesis Example 1, a titanyl phthalocyanine pigment water paste was synthesized, and crystal conversion was performed as follows to obtain phthalocyanine crystals having smaller primary particles than Comparative Synthesis Example 1.

  1500 parts of tetrahydrofuran was added to 60 parts of the water paste before crystal conversion obtained in Comparative Synthesis Example 1, and the mixture was vigorously stirred (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature. When the color changed to light blue (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filtration device were washed with tetrahydrofuran to obtain a wet cake of pigment. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 58 parts of titanyl phthalocyanine crystals.

Further, 30 g of this titanyl phthalocyanine crystal was immersed in 300 g of tetrahydrofuran, and a second crystal conversion was performed. After leaving it immersed for 12 hours, it was separated by filtration and dried under reduced pressure under the same conditions as above to obtain a titanyl phthalocyanine crystal used in the present invention. This is designated as Pigment 2.
(Synthesis Example 2)
The treatment was performed in the same manner as in Synthesis Example 1 except that the second crystal conversion operation in Synthesis Example 1 was changed to the following conditions to obtain a titanyl phthalocyanine crystal of the present invention (see FIG. 15). This is designated as Pigment 3.
(Second crystal conversion process)
30 g of titanyl phthalocyanine crystals subjected to the first crystal conversion treatment were subjected to mechanical shearing force for 5 minutes by a commercially available mixer, and then the powder was taken out.
(Synthesis Example 3)
The treatment was performed in the same manner as in Synthesis Example 1 except that the second crystal conversion operation in Synthesis Example 1 was changed to the following conditions to obtain a titanyl phthalocyanine crystal of the present invention. This is designated as Pigment 4.
(Second crystal conversion process)
30 g of titanyl phthalocyanine crystals subjected to the first crystal conversion treatment were put into a φ90 mm glass pot together with 2 kg of φ6 mm zirconia balls, and after dry milling for 10 minutes, the powder was taken out.
(Comparative Synthesis Example 2)
The treatment was performed in the same manner as in Synthesis Example 1 except that the second crystal conversion solvent in Synthesis Example 1 was changed from tetrahydrofuran to methanol to obtain titanyl phthalocyanine crystals. This is designated as Pigment 5.
(Comparative Synthesis Example 3)
In Comparative Synthesis Example 1, treatment was performed in the same manner as in Comparative Synthesis Example 1 except that 2-butanone was used in place of tetrahydrofuran as the first crystal conversion solvent and the second crystal conversion was not performed, and the titanyl phthalocyanine crystals were obtained. Obtained. This is designated as Pigment 6.

The titanyl phthalocyanine powder obtained as described above was subjected to X-ray diffraction spectrum measurement under the following conditions.
(X-ray diffraction spectrum measurement conditions)
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds With respect to the pigments 1 to 4 obtained from Comparative Synthesis Example 1 and Synthesis Examples 1 to 3, similar X-ray diffraction spectra were exhibited in any case except for the peak intensity of 26.3 °. . As a representative example, an X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Synthesis Example 2 is shown in FIG. 19 (the arrow in the figure is a peak at 26.3 °, and the peak intensity ratio is 8%).

  Bragg angle 2θ with respect to Cu-Kα ray (wavelength 1.542 mm) has a maximum peak at 27.2 ± 0.2 ° and a peak at minimum angle 7.3 ± 0.2 °, and a peak at 7.3 ° It can be seen that this is a titanyl phthalocyanine powder having no peak between 1 and 9.4 ° and further having a peak at 26.3 °.

  A part of the water paste obtained in Comparative Synthesis Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain a low crystalline titanyl phthalocyanine powder. An X-ray diffraction spectrum of the dry powder of the water paste is shown in FIG.

  An X-ray diffraction spectrum of the titanyl phthalocyanine crystal (pigment 5) obtained in Comparative Synthesis Example 2 is shown in FIG. There is no peak at 26.3 °.

  The X-ray diffraction spectrum of the titanyl phthalocyanine crystal (pigment 6) obtained in Comparative Synthesis Example 3 is shown in FIG. It had the lowest angle diffraction peak at 7.5 °.

  The arrow in the figure is a peak at 26.3 °, and the peak intensity ratio is 8%.

  A portion of titanyl phthalocyanine (water paste) before crystal transformation prepared in Comparative Synthesis Example 1 was diluted with ion-exchanged water to approximately 1% by weight, and the surface was scooped with a copper net having been subjected to conductive treatment. The particle size of phthalocyanine was observed with a transmission electron microscope (TEM, Hitachi: H-9000NAR) at a magnification of 75000 times. The average particle size was determined as follows.

  The TEM image observed as described above is taken as a TEM photograph, and 30 titanyl phthalocyanine particles (a shape close to a needle shape) projected are arbitrarily selected, and the size of each major axis is measured. The arithmetic average of the major diameters of the 30 individuals measured was determined as the average particle size.

  The average particle size in the water paste in Synthesis Example 1 determined by the above method was 0.06 μm.

  In addition, the titanyl phthalocyanine crystal after crystal conversion just before filtration in Comparative Synthesis Example 1 and Synthesis Example 1 was diluted with tetrahydrofuran to about 1% by weight, and observed in the same manner as the above method. The average particle size obtained as described above is shown in Table 1. In addition, the titanyl phthalocyanine crystal produced in Comparative Synthesis Example 1 and Synthesis Example 1 did not necessarily have the same shape of all crystals (a shape close to a triangle, a shape close to a square, etc.). For this reason, the calculation was performed with the length of the largest diagonal line of the crystal as the major axis.

(Comparative Synthesis Example 4)
A pigment was prepared according to the method described in Patent Document 10 and Example 1. That is, the wet cake produced in the previous Comparative Synthesis Example 1 was dried, 1 g of the dried product was added to 50 g of polyethylene glycol, and sand milling was performed with 100 g of glass beads. After the crystal transition, the mixture was washed successively with dilute sulfuric acid and aqueous ammonium hydroxide and dried to obtain a pigment. This is designated as Pigment 7.
(Comparative Synthesis Example 5)
A pigment was produced according to the method described in Patent Document 11 and Production Example 1. That is, the wet cake prepared in Comparative Synthesis Example 1 was dried, and 1 g of the dried product was stirred (50 ° C.) in a mixed solvent of 10 g of ion-exchanged water and 1 g of monochlorobenzene for 1 hour, and then methanol and ion-exchanged water. The pigment was obtained by washing and drying. This is designated as Pigment 8.
(Comparative Synthesis Example 6)
A pigment was produced according to the method described in the production example of Patent Document 12. That is, 9.8 g of phthalodinitrile and 75 ml of 1-chloronaphthalene are stirred and mixed, and 2.2 ml of titanium tetrachloride is added dropwise under a nitrogen stream. After completion of the dropping, the temperature was gradually raised to 200 ° C., and the reaction was carried out by stirring for 3 hours while maintaining the reaction temperature between 200 ° C. and 220 ° C. After completion of the reaction, the mixture was allowed to cool to 130 ° C., filtered while hot, then washed with 1-chloronaphthalene until the powder turned blue, then washed several times with methanol, and further heated at 80 ° C. After washing several times with water, it was dried to obtain a pigment. This is designated as Pigment 9.
(Comparative Synthesis Example 7)
A pigment was prepared according to the method described in Patent Document 13 and Synthesis Example 1. That is, 5 parts of α-type TiOPc was subjected to crystal conversion treatment at 100 ° C. for 10 hours with a sand grinder together with 10 g of sodium chloride and 5 g of acetophenone. This was washed with ion-exchanged water and methanol, purified with dilute sulfuric acid aqueous solution, washed with ion-exchanged water until the acid content disappeared, and dried to obtain a pigment. This is designated as Pigment 10.
(Comparative Synthesis Example 8)
A pigment was prepared according to the method described in Patent Document 14 and Example 1. That is, after 20.4 parts of O-phthalodinitrile and 7.6 parts of titanium tetrachloride were heated in quinoline at 50 ° C. for 2 hours at 200 ° C., the solvent was removed by steam distillation, 2% hydrochloric acid, and then 2 Purified with an aqueous sodium hydroxide solution, washed with methanol and N, N-dimethylformamide and dried to obtain titanyl phthalocyanine. 2 parts of this titanyl phthalocyanine is dissolved little by little in 40 parts of 98% sulfuric acid at 5 ° C., and the mixture is stirred for about 1 hour while maintaining the temperature at 5 ° C. or less. Subsequently, the sulfuric acid solution is slowly poured into 400 parts of ice water stirred at a high speed, and the precipitated crystals are filtered. The crystals are washed with distilled water until no acid remains, and a wet cake is obtained. The cake was stirred in 100 parts of THF for about 5 hours, filtered, washed with THF and dried to obtain a pigment. This is designated as Pigment 11.
(Comparative Synthesis Example 9)
A pigment was produced according to the method described in Patent Document 15 and Synthesis Example 2. That is, 10 parts of the wet cake prepared in the previous Comparative Synthesis Example 1 was mixed with 15 parts of sodium chloride and 7 parts of diethylene glycol, and milled for 60 hours with an automatic mortar under heating at 80 ° C. Next, sufficient washing was performed to completely remove sodium chloride and diethylene glycol contained in the treated product. After drying this under reduced pressure, 200 parts of cyclohexanone and glass beads having a diameter of 1 mm were added, and the mixture was treated with a sand mill for 30 minutes to obtain a pigment. This is designated as Pigment 12.
(Comparative Synthesis Example 10)
A pigment was produced according to the method described in Patent Document 14 and Example 4. That is, the wet cake obtained in the previous Comparative Synthesis Example 8 was washed with 5% hydrochloric acid, washed with water and filtered until neutral, and dried. Further, this was dispersed with THF in a ball mill for 10 hours, filtered and dried to obtain a pigment powder. This is designated as Pigment 13.
(Comparative Synthesis Example 11)
A pigment was produced according to the method described in Patent Document 16, Production Example 1 and Production Example 2.

  That is, 97.5 g of phthalodinitrile is added to 750 ml of α-chloronaphthalene, and then 22 ml of titanium tetrachloride is added dropwise under a nitrogen atmosphere. After dropping, the temperature was raised, and the mixture was reacted at 200 to 220 ° C. for 3 hours with stirring, then allowed to cool, filtered hot at 100 to 130 ° C., and washed with 200 ml of α-chloronaphthalene heated to 100 ° C. Furthermore, the hot-washing process (100 degreeC, 1 hour) was performed 3 times with 200 ml N-methylpyrrolidone. Subsequently, the suspension was washed with 300 ml of methanol at room temperature, and further washed with 500 ml of methanol for 1 hour. This is designated as phthalocyanine 1.

  Next, phthalocyanine 1 was ground in a sand grind mill for 20 hours, then placed in a suspension of 400 ml of water and 40 ml of o-dichlorobenzene, and heat treated at 60 ° C. for 1 hour. This is designated as phthalocyanine 2.

Furthermore, according to Patent Document 16 Example 1, phthalocyanine 1 and phthalocyanine 2 were mixed by 6 parts by weight and 4 parts by weight, respectively, 200 parts by weight of n-propanol was added, and the mixture was pulverized by a sand grind mill for 10 hours and atomized and dispersed. Went. This was dried to obtain phthalocyanine powder. This is designated as Pigment 14.
(Comparative Synthesis Example 12)
A pigment was prepared according to the method for producing a titanyl phthalocyanine crystal of Patent Document 3. That is, 58 g of 1,3-diiminoisoindoline and 51 g of tetrabutoxy titanium were reacted in 210 mL of α-chloronaphthalene at 210 ° C. for 5 hours, and then washed in the order of α-chloronaphthalene and dimethylformamide (DMF). Thereafter, it was washed with hot DMF, hot water and methanol and dried to obtain 50 g of titanyl phthalocyanine. 4 g of titanyl phthalocyanine was added to 400 g of concentrated sulfuric acid cooled to 0 ° C., followed by stirring at 0 ° C. for 1 hour. After confirming that phthalocyanine was completely dissolved, it was added to a 800 mL water / 800 mL toluene mixture cooled to 0 ° C. After stirring at room temperature for 2 hours, the precipitated phthalocyanine crystal was separated from the mixture and washed with methanol and water in this order. After confirming the neutrality of the washing water, the phthalocyanine crystal was separated from the washing water and dried to obtain 2.9 g of titanyl phthalocyanine crystal. This is designated as Pigment 15.

  The pigments 7 to 15 prepared in the above Comparative Synthesis Examples 4 to 12 were measured for X-ray diffraction spectra by the same method as described above, and confirmed to be the same as the spectra described in the respective publications. Table 2 shows the characteristics of the peak positions of the X-ray diffraction spectra of the pigments 1 to 15.

(Dispersion Preparation Example 1)
Pigment 1 prepared in Comparative Synthesis Example 1 was dispersed under the following composition under the following conditions to prepare a dispersion as a charge generation layer coating solution.

Titanyl phthalocyanine pigment (Pigment 1) 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts A commercially available bead mill disperser was used to dissolve polyvinyl butyral using PSZ balls having a diameter of 0.5 mm All butanone and pigment were added, and the rotor rotation speed was 1200 r. p. m. And dispersion was performed for 30 minutes to prepare a dispersion (referred to as dispersion 1).
(Dispersion Preparation Examples 2 to 15)
In place of Pigment 1 used in Dispersion Preparation Example 1, pigments 2 to 15 prepared in Synthesis Examples 1 to 3 and Comparative Synthesis Examples 2 to 12 were used, respectively, and dispersed under the same conditions as Dispersion Preparation Example 1. Liquids were prepared (corresponding to the pigment numbers, dispersions 2 to 15, respectively).
(Dispersion Preparation Example 16)
The dispersion 1 prepared in Dispersion Preparation Example 1 was filtered using a cotton wind cartridge filter, TCW-1-CS (effective pore size 1 μm) manufactured by Advantech. In the filtration, a pump was used and filtration was performed under pressure (referred to as dispersion liquid 16).
(Dispersion Preparation Example 17)
Dispersion was performed by pressure filtration in the same manner as in Dispersion Preparation Example 16 except that the filter used in Dispersion Preparation Example 16 was changed to a cotton wind cartridge filter manufactured by Advantech, TCW-3-CS (effective pore size 3 μm). A liquid was prepared (referred to as dispersion liquid 17).
(Dispersion Preparation Example 18)
Dispersion was performed by pressure filtration in the same manner as in Dispersion Preparation Example 16, except that the filter used in Dispersion Preparation Example 15 was changed to an Advantech Co., Ltd. cotton wind cartridge filter, TCW-5-CS (effective pore size 5 μm). A liquid was prepared (referred to as dispersion 18).
(Dispersion Preparation Example 19)
Dispersion was carried out by changing the dispersion conditions in Dispersion Preparation Example 1 as follows (referred to as Dispersion 19).

Rotor rotation speed: 1000 r. p. m. For 20 minutes.
(Dispersion Preparation Example 20)
The dispersion prepared in Dispersion Preparation Example 19 was filtered using a cotton wind cartridge filter, TCW-1-CS (effective pore size 1 μm) manufactured by Advantech. During filtration, a pump was used and filtration was performed in a pressurized state. During the filtration, the filter was clogged, and it was not possible to filter all the dispersions. Therefore, the following evaluation has not been conducted.

  The particle size distribution of the pigment particles in the dispersion prepared as described above was measured by HORIBA, Ltd .: CAPA-700. The results are shown in Table 3.

(Photoreceptor Preparation Example 1)
An undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were sequentially applied and dried on an aluminum cylinder (JIS1050) having a diameter of 60 mm, and an undercoat layer of 3.5 μm, A charge generation layer and a 28 μm charge transport layer were formed to produce a laminated photoreceptor (referred to as photoreceptor 1). The film thickness of the charge generation layer was adjusted so that the transmittance of the charge generation layer at 405 nm was 23%. The charge generation layer transmittance was measured by applying a charge generation layer coating solution having the following composition to an aluminum cylinder wrapped with a polyethylene terephthalate film under the same conditions as the preparation of the photoreceptor, and coating the charge generation layer as a comparative control. The transmittance of 405 nm was evaluated with a commercially available spectrophotometer (Shimadzu: UV-3100).
◎ Undercoat layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd.) 70 parts Alkyd resin 15 parts (Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals)
Melamine resin 10 parts (Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals)
2-butanone 100 parts Charge generation layer coating solution Dispersion 1 prepared earlier was used.
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula 7 parts

80 parts of methylene chloride (Photoconductor Preparation Examples 2 to 19)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating liquid (dispersion 1) used in Photoconductor Preparation Example 1 was changed to dispersions 2 to 19, respectively. In addition, the film thickness of the charge generation layer was adjusted so that the transmittance at 405 nm was 23% when all the coating solutions were used, as in Photoreceptor Production Example 1.
(Examples 1 to 3, Reference Examples 1 and 2 and Comparative Examples 1 to 14)
The electrophotographic photoconductors of photoconductor production examples 1 to 19 produced as described above are mounted on the image forming apparatus shown in FIG. 8 and charged using a scorotron charging member under the following charging conditions to perform image exposure. A semiconductor laser having an oscillation wavelength of 655 nm was used as a light source, a beam having a major axis of 45 μm was formed by an image exposure apparatus comprising a coupling lens, an aperture, a cylindrical lens, a polygon mirror, and a scanning lens, and writing was performed on the photoconductor. For development, two-component development (toner with a volume average particle size of 6.5 μm) is performed, a transfer belt is used as a transfer member, a 780 nm LED is used for charge removal light, and the entire surface of the photosensitive member is irradiated with light for charge removal. It was. Using a chart with a writing rate of 6%, continuous 50,000 sheets were printed (the test environment was 22 ° C.-55% RH).
Charging condition 1:
Discharge voltage: -6.0 kV
Grid voltage: -920V (surface potential of unexposed portion of photoconductor is -900V)
Development bias: -650V
Charging condition 2:
Discharge voltage: -5.8 kV
Grid voltage: -780V (surface potential of unexposed portion of photoconductor is -750V)
Development bias: -500V
The following two evaluations were performed after printing 50,000 sheets.
(I) Evaluation of soiling:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot formation state A halftone image (one dot image having a diameter of 50 μm) was formed, and the dot formation state was observed (dot scattering state and dot reproducibility).
(Iii) Dot outline The sharpness of the periphery (edge) of the dot was evaluated. The results are shown in Table 4.

  Further, after the above test at 22 ° C.-55% RH, the above charging condition is maintained (charging condition is only condition 1), 10,000 sheets at 10 ° C.-15% RH, 1 at 30 ° C.-90% RH Ten thousand running tests were performed, and images after 10,000 images were evaluated in the same manner. The results are shown in Table 5 and Table 6, respectively.

The images of Examples 1 to 3 and Reference Examples 1 and 2 were all good images, but in the image after 20,000 sheets in a 10 ° C.-15% RH environment, the image of Example 2 was Compared with the images of Example 1 and Example 3 and Reference Examples 1 and 2 , the image density was low.

(Examples 4 to 6, Reference Examples 3 and 4 and Comparative Examples 15 to 28)
The electrophotographic photoreceptors of photoreceptor preparation examples 1 to 19 prepared as described above are mounted on the image forming apparatus shown in FIG. 8 and are charged under the following charging conditions using a contact-type charging member (a charging roller having a diameter of 20 mm). The surface of the photoconductor is charged to −880 V, a semiconductor laser having an oscillation wavelength of 655 nm is used as an image exposure light source, and the long diameter is measured by an image exposure apparatus including a coupling lens, an aperture, a cylindrical lens, a polygon mirror, and a scanning lens. A 45 μm beam was formed, and writing was performed on the photoreceptor. For development, two-component development (toner having a volume average particle diameter of 6 μm) was performed, a transfer belt was used as a transfer member, a 780 nm LED was used for charge removal light, and the entire surface of the photoreceptor was irradiated with light to perform charge removal. Using a chart with a writing rate of 6%, continuous 50,000 sheets were printed (the test environment was 22 ° C.-55% RH).

Charging conditions:
DC bias: -1580V
The following two evaluations were performed after printing 50,000 sheets.
(I) Evaluation of background dirt:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot formation state A halftone image (one dot image having a diameter of 50 μm) was formed, and the dot formation state was observed (dot scattering state and dot reproducibility).
(Iii) Dot outline The sharpness of the periphery (edge) of the dot was evaluated.

  The soil stain rank was evaluated in four stages. Very good ones were indicated by 、, good ones by ○, slightly inferior by Δ, and very bad by x. The results are shown in Table 7.

(Photoreceptor Preparation Example 20)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 2, except that the charge transport layer coating solution in Photoconductor Preparation Example 2 was changed to one having the following composition.

◎ Charge transport layer coating solution 10 parts of polymer charge transport material having the following composition (weight average molecular weight: about 135,000)

0.5 parts of additive with the following structure

100 parts of methylene chloride (Photoconductor Preparation Example 21)
Similar to Photoconductor Preparation Example 2, except that the thickness of the charge transport layer in Photoconductor Preparation Example 2 was 23 μm, a protective layer coating solution having the following composition was applied and dried on the charge transport layer, and a protective layer of 5 μm was provided. A photoreceptor was prepared.
◎ Protective layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula: 7 parts

4 parts of alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Cyclohexanone 500 parts Tetrahydrofuran 150 parts (Photoconductor Preparation Example 22)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 21, except that the alumina fine particles in the protective layer coating solution in Photoconductor Preparation Example 21 were changed to the following.

4 parts of titanium oxide fine particles (specific resistance: 1.5 × 10 ¹⁰ Ω · cm, average primary particle size: 0.5 μm)
(Photoconductor Preparation Example 23)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 21, except that the alumina fine particles in the protective layer coating solution in Photoconductor Preparation Example 21 were changed to the following.

4 parts of tin oxide-antimony oxide powder (specific resistance: 10 ⁶ Ω · cm, average primary particle size 0.4 μm)
(Photoconductor Preparation Example 24)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 40 except that the protective layer coating solution in the photosensitive member preparation example 21 was changed to one having the following composition.
◎ Protective layer coating solution 17 parts of polymer charge transport material of the following structural formula

(Weight average molecular weight: about 135000)
4 parts of alumina fine particles (specific resistance: 2.5 × 10 ¹² Ω · cm, average primary particle size: 0.4 μm)
Cyclohexanone 500 parts Tetrahydrofuran 150 parts (Photoconductor Preparation Example 25)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 21 except that the protective layer coating solution in the photosensitive member preparation example 21 was changed to one having the following composition.
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts

Antioxidant (Sanol LS2626: manufactured by Sankyo Chemical Co., Ltd.) 1 part Curing agent (dibutyltin acetate) 1 part 2-propanol 200 parts (Photoconductor Preparation Example 26)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 21 except that the protective layer coating solution in the photosensitive member preparation example 21 was changed to one having the following composition.
◎ Protective layer coating solution Methyltrimethoxysilane 100 parts 3% acetic acid 20 parts Charge transporting compound with the following structure 35 parts

α-alumina particles (Sumicorundum AA-03: manufactured by Sumitomo Chemical Co., Ltd.) 15 parts Antioxidant (Sanol LS2626: manufactured by Sankyo Chemical Co., Ltd.) 1 part Polycarboxylic acid compound BYK P104: manufactured by BYK Chemie 0.4 part Curing agent (dibutyl) Tin acetate) 1 part 2-propanol 200 parts

(Photoconductor Preparation Example 27)
The aluminum cylinder (JIS 1050) in photoreceptor preparation example 2 is subjected to the following anodic oxide film treatment, and then a charge generation layer and a charge transport layer are provided in the same manner as in photoreceptor preparation example 2 without providing an undercoat layer. Was made.
◎ Anodic oxide film treatment After mirror polishing of the support surface, degreasing and water washing, immersion in an electrolytic bath with a liquid temperature of 20 ° C and sulfuric acid of 15 vol%, and an anodic oxide film treatment at an electrolytic voltage of 15 V for 30 minutes. Was done. Further, after washing with water, sealing treatment was performed with a 7% nickel acetate aqueous solution (50 ° C.). Thereafter, the substrate was washed with pure water to obtain a support on which a 7 μm anodic oxide film was formed.
(Examples 7 to 14 )
As described above, the electrophotographic photosensitive member manufactured in the photosensitive member manufacturing examples 20 to 27 is mounted on the image forming apparatus shown in FIG. 8 and charged under the following charging conditions using a scorotron type charging member. As a semiconductor laser having an oscillation wavelength of 655 nm, a beam having a major axis of 45 μm was formed by an image exposure apparatus composed of a coupling lens, an aperture, a cylindrical lens, a polygon mirror, and a scanning lens, and writing was performed on the photoreceptor. For development, two-component development (toner with a volume average particle size of 6.5 μm) is performed, a transfer belt is used as a transfer member, a 780 nm LED is used for charge removal light, and the entire surface of the photosensitive member is irradiated with light for charge removal. It was. Using a chart with a writing rate of 6%, continuous 50,000 sheets were printed (the test environment was 22 ° C.-55% RH).
Charging conditions:
Discharge voltage: -6.0 kV
Grid voltage: -920V (surface potential of unexposed portion of photoconductor is -900V)
Development bias: -650V
The following two evaluations were performed after printing 50,000 sheets.
(I) Evaluation of soiling:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot formation state A halftone image (one dot image having a diameter of 50 μm) was formed, and the dot formation state was observed (dot scattering state and dot reproducibility).
(Iii) Dot outline The sharpness of the periphery (edge) of the dot was evaluated.

In each case, the rank evaluation was performed in 4 stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x. Table 8 shows the above results.

  In addition, the amount of abrasion of the photosensitive layer after printing 50,000 sheets (the amount of abrasion of the protective layer when a protective layer is provided) was measured. The results are shown in Table 8 together with the case of Example 1.

(Photoreceptor Preparation Example 28)
The aluminum cylinder of the photoreceptor preparation example 1 was changed to one having a diameter of 30 mm, and a photoreceptor having the same composition as that of the photoreceptor preparation example 1 was prepared.
(Photoconductor Preparation Example 29)
The aluminum cylinder of Photoreceptor Preparation Example 2 was changed to one having a diameter of 30 mm, and a photoconductor having the same composition as Photoreceptor Preparation Example 2 was prepared.
(Photoreceptor Preparation Example 30)
The aluminum cylinder of the photoreceptor preparation example 4 was changed to one having a diameter of 30 mm, and a photoreceptor having the same composition as that of the photoreceptor preparation example 4 was prepared.
(Photoreceptor Preparation Example 31)
The aluminum cylinder of the photoreceptor preparation example 13 was changed to one having a diameter of 30 mm, and a photoreceptor having the same composition as that of the photoreceptor preparation example 13 was prepared.
(Photoconductor Preparation Example 32)
The aluminum cylinder of the photoreceptor preparation example 14 was changed to one having a diameter of 30 mm to prepare a photoreceptor having the same composition as the photoreceptor preparation example 14.
(Photoconductor Preparation Example 33)
The aluminum cylinder of the photoreceptor preparation example 15 was changed to one having a diameter of 30 mm, and a photoreceptor having the same composition as that of the photoreceptor preparation example 15 was prepared.
(Examples 15 and 16 and Comparative Examples 29 to 32)
The photoconductors of the photoconductor production examples 28 to 33 produced as described above are mounted on a single process cartridge for an image forming apparatus as shown in FIG. 10 together with a charging member (scorotron charging), and further, as shown in FIG. It was installed in an image forming apparatus. In the four image forming elements, a charging member is charged with a scorotron charging member so that the surface potential of the photosensitive member becomes −900 V, and a semiconductor laser having an oscillation wavelength of 655 nm is used as an image exposure light source. A beam having a major diameter of 40 μm was formed by an image exposure apparatus composed of an aperture, a cylindrical lens, a polygon mirror, and a scanning lens, and writing was performed on the photoconductor. For development, two-component development (toner with a volume average particle size of 6.5 μm) is performed, a transfer belt is used as a transfer member, a 780 nm LED is used for charge removal light, and the entire surface of the photosensitive member is irradiated with light for charge removal. It was. Using a chart with a writing rate of 6%, continuous 30,000 sheets were printed (the test environment was 22 ° C.-55% RH).

In addition, the following three evaluations were implemented after 30,000 sheets of image evaluation.
(I) Evaluation of background dirt:
A white solid image was output, and rank evaluation was performed from the number and size of black spots generated on the background.
(Ii) Evaluation of dot formation state A halftone image (one dot image having a diameter of 45 μm) was formed, and the dot formation state was observed (dot scattering state and dot reproducibility).
(Iii) Dot outline The sharpness of the periphery (edge) of the dot was evaluated.
(Iv) Evaluation of color reproducibility The same full-color image was output after the initial state of the photoreceptor and 30,000 sheets running, and an attempt was made to evaluate the color reproducibility.
In each case, the rank evaluation was performed in 4 stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x. The above results are shown in Table 9.

Finally, 7.3 ° which is the lowest angle peak of the Bragg angle θ, which is a feature of the titanyl phthalocyanine crystal used in the present invention, will be verified as to whether or not it is the same as the lowest angle 7.5 ° of known materials.
(Measurement Example 1)
To the pigment obtained in Comparative Synthesis Example 3 (minimum angle 7.3 °), 3% by weight of a pigment prepared in the same manner as the pigment described in Patent Document 8 (having a maximum diffraction peak at 7.5 °) was added, The mixture was mixed in a mortar, and the X-ray diffraction spectrum was measured in the same manner as before. The X-ray diffraction spectrum of Measurement Example 1 is shown in FIG.
(Measurement example 2)
To the pigment obtained in Comparative Synthesis Example 2 (minimum angle 7.5 °), 3% by weight of a pigment prepared in the same manner as the pigment described in Patent Document 8 (having a maximum diffraction peak at 7.5 °) was added, The mixture was mixed in a mortar, and the X-ray diffraction spectrum was measured in the same manner as before. The X-ray diffraction spectrum of Measurement Example 2 is shown in FIG.

  In the spectrum of FIG. 23, it can be seen that there are two independent peaks at 7.3 ° and 7.5 ° on the low angle side, and at least the peaks at 7.3 ° and 7.5 ° are different. . On the other hand, in the spectrum of FIG. 24, the low angle side peak exists only at 7.5 °, which is clearly different from the spectrum of FIG.

  From the above, it can be seen that the minimum angle peak of 7.3 ° in the titanyl phthalocyanine crystal of the present invention is different from the 7.5 ° peak in the known titanyl phthalocyanine crystal.

It is a schematic diagram of optical carrier generation. It is a figure showing that a dot diffuses in charge transportation. It is a figure showing the electric field strength and the state of dot (toner image) formation. It is a figure showing the relationship between electric field strength and background dirt. FIG. 3 is a schematic diagram of an electrostatic latent image (dot) of a photoreceptor using a charge generating material having a small particle size and a small particle size distribution. FIG. 3 is a schematic diagram of an electrostatic latent image (dot) of a photoreceptor using a charge generating material having a large particle size and a large particle size distribution (or including coarse particles). It is a figure for demonstrating the difference in the light attenuation characteristic of the photoreceptor at the time of using the charge generating substance from which particle sizes differ. A is a case where the particle size is large, and B is a case where the particle size is small. 1 is a schematic view for explaining an electrophotographic process and an image forming apparatus of the present invention. 1 is a schematic view for explaining a tandem-type full-color image forming apparatus of the present invention. FIG. FIG. 4 is a diagram for explaining a process cartridge for an image forming apparatus according to the present invention. It is a TEM image of amorphous titanyl phthalocyanine. The scale bar in the figure is 0.2 μm. It is a TEM image of titanyl phthalocyanine after crystal conversion. The scale bar in the figure is 0.2 μm. It is a TEM image of a titanyl phthalocyanine crystal that has undergone crystal conversion in a short time. The scale bar in the figure is 0.2 μm. It is a figure which shows the state of the dispersion liquid when dispersion time is short. It is a figure which shows the state of the dispersion liquid when dispersion time is long. It is a figure which shows an average particle diameter and a particle size distribution about the dispersion liquid of FIG. It is a figure showing the layer structure of the electrophotographic photosensitive member used for this invention. It is a figure showing the layer structure of another electrophotographic photosensitive member used for this invention. 6 is a diagram illustrating an XD spectrum of titanyl phthalocyanine synthesized in Synthesis Example 2. FIG. It is a figure showing the XD spectrum of the dry powder of the water paste. 6 is a diagram showing an XD spectrum of titanyl phthalocyanine synthesized in Comparative Synthesis Example 2. FIG. 6 is a diagram showing an XD spectrum of titanyl phthalocyanine synthesized in Comparative Synthesis Example 3. FIG. It is a figure showing the XD spectrum of the titanyl phthalocyanine used in the measurement example 1. It is a figure showing the XD spectrum of the titanyl phthalocyanine used in the measurement example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charging roller 5 Image exposure part 6 Development unit 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 14 Fur brush 15 Cleaning brushes 16Y, 16M, 16C, 16K Photoconductors 17Y, 17M, 17C, 17K Charging members 18Y, 18M, 18C, 18K Laser beams 19Y, 19M, 19C, 19K Developing members 20Y, 20M, 20C, 20K Cleaning members 21Y, 21M, 21C, 21K Transfer brush 22 Transfer conveying belt 23 Registration roller 24 Fixing Apparatus 25Y, 25M, 25C, 25K Image forming element 26 Transfer object 31 Conductive support 35 Charge generation layer 37 Charge transport layer 39 Protective layer 101 Photoconductor 102 Charging means 103 Exposure 104 Developing means 105 Transfer body 106 Transfer means 07 cleaning means

Claims (12)

An electrophotographic photosensitive member formed by forming at least a charge transport layer and a charge generating layer having a titanyl phthalocyanine crystal as a charge generating material on a conductive support, and the electrophotographic photosensitive member has an electric field strength of 30 V / μm or more. In an image forming apparatus provided with charging means to be applied and exposure means for irradiating the electrophotographic photosensitive member with writing light using a light source having a beam diameter of 50 μm or less,
The titanyl phthalocyanine crystal as a diffraction peak of Bragg angles 2θ for CuKα ray (wavelength 1.542 Å) (± 0.2 °), has a 27.2 maximum diffraction peak, 9.4 °, 9.6 ° and 24.0 ° having a main peak, has a 7.3 ° peak as a diffraction peak of the lowest angle side peak between the peaks and the 9.4 ° peak of 7.3 ° It has a peak at not without, and 26.3 ° a,
The titanyl phthalocyanine crystal has a maximum diffraction peak at 7.0 to 7.5 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα ray (wavelength 1.542Å). Crystal transformation by mixing and stirring amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine having an average primary particle size of 0.1 μm or less with an organic solvent in the presence of water. Before the average particle size of the primary particles after the crystal growth grows larger than 0.25 μm, it is produced by crystal conversion of the crystal obtained by fractionating with the organic solvent,
Average particle size of images forming device you wherein the Ru der below 0.25μm of the primary particles of the titanyl phthalocyanine crystal. The titanyl phthalocyanine crystal has a peak intensity of 26.3 ° in a range of 0.1 to 5% with respect to the peak intensity of the maximum diffraction peak of 27.2 °. The image forming apparatus described in 1. The charge transport layer, the image forming apparatus according to claim 1 or 2, characterized in that it contains a polycarbonate having a triarylamine structure in a main chain and / or side chain. Said electrophotographic photosensitive member, an image forming apparatus according to any one of claims 1 to 3, characterized in that it has a protective layer on the outermost layer. The image forming apparatus according to claim 4 , wherein the protective layer contains a metal oxide having a specific resistance of 10 ¹⁰ Ω · cm or more. The protective layer, the image forming apparatus according to claim 4 or 5, characterized that you containing a polymer charge transport material. The protective layer, the image forming apparatus claimed in any one of claims 4 to 6, characterized that you containing a binder resin having a crosslinked structure. Binder resin having a pre-listen bridge structure, the image forming apparatus according to claim 7, characterized in that it comprises a charge transporting moiety. Surface of the conductive support, an image forming apparatus according to any one of claims 1 to 8, characterized in that it is anodized film processing. An image forming element, the charging unit, the exposing unit, developing unit, transfer unit, and to any one of claims 1 to 9, characterized in that the electrophotographic photoconductor imaging element a plurality array of The image forming apparatus described. Before Symbol band conductive means, an image forming apparatus according to any one of claims 1 to 10, wherein the applying an alternating superimposed voltage. The charging unit, the exposing unit, and one means selected from the group consisting of the developing means and cleaning means and the electrophotographic photosensitive member is characterized by being mounted detachably a process cartridge together the image forming apparatus according to any one of claims 1 to 11.