JP2014197187A - Manufacturing method of coating liquid for photosensitive layer formation, electrophotographic photoreceptor manufactured by using the coating liquid, image forming apparatus, and electrophotographic cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easier manufacturing method of a coating liquid for photosensitive layer formation, an electrophotographic photoreceptor that can form high-quality images using the coating liquid and has improved electrical characteristics, an image forming apparatus using the photoreceptor, and an electrophotographic cartridge.SOLUTION: There is provided an easy manufacturing method of a coating liquid for photosensitive layer formation for an electrophotographic photoreceptor having a photosensitive layer containing a phthalocyanine composition, and including causing a specific phthalocyanine composition to be subjected to dry granulation processing to a specific particle diameter, and then adding a solvent thereto to be subjected to wet dispersion. An electrophotographic photoreceptor manufactured by using the coating liquid has excellent sensitivity and dark decay characteristics.

Description

  The present invention relates to a method for producing a coating solution for forming a photosensitive layer used when a photosensitive layer of an electrophotographic photosensitive member is coated and dried, and formed by coating and drying using a coating solution produced by the production method. The present invention relates to an electrophotographic photosensitive member, an image forming apparatus using the photosensitive member, and an electrophotographic cartridge using the photosensitive member. An electrophotographic photosensitive member having a photosensitive layer formed by applying and drying a photosensitive layer forming coating solution produced by the production method of the present invention can be suitably used for an electrophotographic printer, facsimile, copying machine and the like.

  The electrophotographic technique is widely used in the fields of copiers, various printers, printing presses and the like because of its excellent immediacy and high quality images. As an electrophotographic photosensitive member that is the core of the electrophotographic technology, an electrophotographic photosensitive member using an organic photoconductive material having advantages such as non-pollution, easy film formation, and easy manufacture (hereinafter simply referred to as “ Also referred to as “photoreceptor”).

  As an electrophotographic photoreceptor using an organic photoconductive material, a so-called dispersion type single-layer photoreceptor in which a photoconductive fine powder is dispersed in a binder resin, a charge generation layer and a charge transport layer are laminated. Multilayer photoreceptors are known. Multilayer photoconductors provide highly efficient charge generating materials and wide and highly safe photoconductors. Also, photoconductors can be easily formed by coating, have high productivity, and are advantageous in terms of cost. For these reasons, they have been developed and put into practical use.

  An electrophotographic photosensitive member using an organic photoconductive substance has the above-mentioned advantages, but does not satisfy all of the characteristics required as an electrophotographic photosensitive member, particularly in the repeated use of copying machines and printers. Since there is a problem that the photosensitive layer gradually deteriorates, it is desired that there is little damage due to repeated use, high sensitivity, low residual potential, and stable electrical characteristics. These characteristics depend largely on the charge generation material, charge transport material, additive, and binder resin. Since the charge generation material needs to have sensitivity to the light source for light input, phthalocyanine pigments and azo pigments are mainly used. Is called.

  The most frequently reported phthalocyanine pigment used as a charge generating substance is oxytitanium phthalocyanine, such as D type (also known as Y type), A type (also known as β type), and B type (also known as α type). Crystalline oxytitanium phthalocyanine is well known. Among them, D-type oxytitanium phthalocyanine is highly sensitive, but its crystal form stability in the coating solution is poor, and depending on conditions, it may be partially converted to another crystal form and the sensitivity may be lowered. A-type and B-type oxytitanium phthalocyanines are stable in crystal form and do not deteriorate in electrical characteristics over time. In addition, D-type oxytitanium phthalocyanine has high sensitivity because water molecules exist in the crystal and it functions as a sensitizer. However, in a low-humidity environment, water molecules are desorbed from the crystal and have high sensitivity. In contrast to the decrease, the A-type and B-type oxytitanium phthalocyanines have little variation in electrical characteristics due to the environment.

A layer of an organic electrophotographic photoreceptor is usually formed by coating and drying a coating solution in which a material is dissolved or dispersed in various solvents because of its high productivity. The coating solution for forming a photosensitive layer is generally produced by wet-dispersing a charge generating substance in an organic solvent using a known mechanical grinding device such as a ball mill, a sand grind mill, a planetary mill, or a roll mill. (For example, see Patent Document 1). However, as higher-quality image formation and improved coating liquid productivity are required, the conventional techniques are still unsatisfactory in terms of images, stabilization of electrical characteristics, and productivity of the coating liquid. There were enough points.

  In addition, in order to easily produce a coating solution for a charge generation layer, a production method in which a charge generation material is dry-dispersed in advance and then wet-dispersed in an organic solvent is known (for example, see Patent Document 2). . It is said that wet dispersion is performed after the particle size of the pigment is dispersed to 250 μm or less by dry dispersion, but in the text, it is preferable to disperse the sieve with a mesh size of 149 μm so that 20 to 50% passes. The role of dry dispersion is to keep extremely large particles fine to some extent as an aid for dispersing the particle size to 0.5 μm or less by wet dispersion. In addition, the pigment used as the charge generating material is not particularly limited, and names of various series of pigments are described in the text. In the examples, azo pigments and oxytitanium phthalocyanine pigments whose crystal types are not specified are described. Is only described. In addition, after dry dispersion, sieving with a sieve having an opening of 250 μm was performed, and then wet dispersion was performed, which included a step of taking out the pigment although it was an easy method for producing a dispersion.

Japanese Patent Laid-Open No. 2001-115054 JP-A-11-30871

  The present invention was devised in view of the background of the above-described electrophotographic technology. It is a simpler method for producing a coating solution for forming a photosensitive layer, enables high-quality image formation using the coating solution, and has electrical characteristics. An object of the present invention is to provide an improved electrophotographic photosensitive member, an image forming apparatus using the photosensitive member, and an electrophotographic cartridge.

  As a result of intensive studies on the above problems, the inventors of the present invention formed a photosensitive layer more easily by grinding a specific phthalocyanine composition to a specific particle size in a dry process and then adding a solvent to wet dispersion. It has been found that a coating liquid can be produced. Furthermore, it has been found that an electrophotographic photosensitive member produced using the coating solution is superior in sensitivity and dark attenuation among electric characteristics as compared with an electrophotographic photosensitive member produced only by wet dispersion.

That is, the gist of the present invention resides in the following six points.
(1) A method for producing a coating solution for forming a photosensitive layer of an electrophotographic photosensitive member having a photosensitive layer containing a phthalocyanine composition on a conductive support, wherein the phthalocyanine composition is powder X-ray diffraction by CuKα characteristics An oxytitanium phthalocyanine composition showing main diffraction peaks in the spectrum at Bragg angles (2θ ± 0.2 °) of 9.3 °, 10.5 °, 13.2 °, 15.1 ° and 26.2 °, or An oxytitanium phthalocyanine composition showing main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 7.6 °, 10.3 °, 22.5 °, 24.2 °, 25.4 ° and 28.6 ° A method for producing a coating solution for forming a photosensitive layer, characterized in that the phthalocyanine composition is dry-grinded until the average particle size of the phthalocyanine composition is 10 μm or less and then wet-dispersed. (Claim 1)
(2) The method for producing a coating solution for forming a photosensitive layer according to (1), wherein as the dry grinding treatment, a dispersion medium is added to the phthalocyanine composition and a treatment is performed using a paint shaker. (Claim 2)
(3) The photosensitive layer formation according to (1) or (2), wherein after the dry grinding process, a solvent is added and wet dispersed without separating the phthalocyanine composition and the dispersion medium. Method for producing a coating liquid for use. (Claim 3)
(4) An electrophotographic photosensitive member having a photosensitive layer containing a phthalocyanine composition on a conductive support, wherein the phthalocyanine composition has a Bragg angle (2θ ± 0. 2 °) oxytitanium phthalocyanine composition exhibiting main diffraction peaks at 9.3 °, 10.5 °, 13.2 °, 15.1 ° and 26.2 °, or Bragg angle (2θ ± 0.2 °) An oxytitanium phthalocyanine composition having main diffraction peaks at 7.6 °, 10.3 °, 22.5 °, 24.2 °, 25.4 ° and 28.6 °, and an average particle of the phthalocyanine composition An electrophotographic photoreceptor, wherein the electrophotographic photosensitive member is one that has been subjected to a dry grinding process and then wet dispersed until the diameter becomes 10 μm or less. (Claim 4)
(5) an electrophotographic photosensitive member, a charging unit for charging the photosensitive member, an image exposing unit for performing image exposure on the charged photosensitive member to form an electrostatic latent image, and the electrostatic latent image with toner. An image forming apparatus comprising: a developing unit that develops the image forming apparatus, wherein the photoreceptor is the electrophotographic photoreceptor according to (4). (Claim 5)
(6) an electrophotographic photosensitive member, a charging unit for charging the photosensitive member, an image exposing unit for performing image exposure on the charged photosensitive member to form an electrostatic latent image, and the electrostatic latent image with toner. The electrophotographic photosensitive member according to (5), wherein at least one of developing means for developing and transfer means for transferring toner to a transfer target is provided. An electrophotographic cartridge characterized by the above. (Claim 6)

  According to the present invention, after dry grinding a specific phthalocyanine composition to a specific particle size, applying a coating solution for forming a photosensitive layer by adding a solvent and performing wet dispersion, forming a photosensitive layer, The manufactured electrophotographic photosensitive member is particularly improved in sensitivity and dark attenuation and has excellent electrical characteristics as compared with an electrophotographic photosensitive member manufactured using a coating solution manufactured only by wet dispersion as in the prior art. According to the image forming apparatus using the electrophotographic photosensitive member of the present invention, a high quality image can be obtained. It is also advantageous from the viewpoint of improving the productivity of the coating liquid.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. The powder X-ray-diffraction spectrum by CuK (alpha) characteristic X-ray of the oxytitanium phthalocyanine composition used in Example 1 is shown. The thin film X-ray-diffraction spectrum by the CuK (alpha) characteristic X-ray of the coating liquid for charge generation layer formation obtained in Example 1 is shown. The powder X-ray-diffraction spectrum by CuK (alpha) characteristic X-ray of the oxytitanium phthalocyanine composition used in Example 6 is shown. The thin film X-ray-diffraction spectrum by the CuK (alpha) characteristic X-ray of the coating liquid for charge generation layer formation obtained in Example 6 is shown. The powder X-ray-diffraction spectrum by CuK (alpha) characteristic X-ray of the oxytitanium phthalocyanine composition used in the comparative example 8 is shown. The thin film X-ray-diffraction spectrum by the CuK (alpha) characteristic X-ray of the coating liquid for charge generation layer formation obtained in the comparative example 8 is shown. The thin film X-ray-diffraction spectrum by the CuK (alpha) characteristic X-ray of the coating liquid for charge generation layer forming obtained in the comparative example 9 is shown.

Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to the following descriptions, and can be appropriately modified and implemented without departing from the gist of the present invention.
The present invention relates to a method for producing a coating solution for forming a photosensitive layer of an electrophotographic photosensitive member, an electrophotographic photosensitive member having a photosensitive layer formed by coating and forming the coating solution, an image forming apparatus using the electrophotographic photosensitive member, and The present invention relates to an electrophotographic cartridge using the electrophotographic photosensitive member. The electrophotographic photoreceptor according to the present invention has a photosensitive layer containing a phthalocyanine composition on a conductive support.

[Photosensitive layer forming coating solution]
The photosensitive layer forming coating solution of the present invention is described in detail below.
<Charge generating material>
As the charge generation material according to the present invention, a phthalocyanine composition is used, and in a powder X-ray diffraction spectrum by CuKα characteristics, Bragg angles (2θ ± 0.2 °) 9.3 °, 10.5 °, 13.2 Oxytitanium phthalocyanine composition showing main diffraction peaks at °, 15.1 ° and 26.2 °, or Bragg angle (2θ ± 0.2 °) 7.6 °, 10.3 °, 22.5 °, 24 An oxytitanium phthalocyanine composition showing main diffraction peaks at .2 °, 25.4 ° and 28.6 ° is used. In the present invention, only when the oxytitanium phthalocyanine composition having the above crystal form is used, the effect of improving the sensitivity and dark decay of electrical characteristics can be seen by performing dry grinding treatment in advance. .

  Main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 9.3 °, 10.5 °, 13.2 °, 15.1 ° and 26.2 ° in the powder X-ray diffraction spectrum by CuKα characteristics The oxytitanium phthalocyanine composition is a crystal type generally called A-type or β-type, and has a Bragg angle (2θ ± 0.2 °) of 7.6 °, 10.3 °, 22.5 °, The oxytitanium phthalocyanine composition showing main diffraction peaks at 24.2 °, 25.4 °, and 28.6 ° is a crystal type generally called B-type or α-type. The oxytitanium phthalocyanine composition according to the present invention may be produced by any method as long as it has these crystal types.

  As an example of the production method, oxytitanium phthalocyanine composition can be produced by producing dichlorotitanium phthalocyanine using phthalonitrile and titanium tetrachloride as raw materials, and then hydrolyzing and treating the dichlorotitanium phthalocyanine. . It is possible to create a crystal form by using a specific solvent in the solvent treatment at this time. For example, N-methyl-2-pyrrolidone is used for the A type, and butanol is used for the B type. Thus, an oxytitanium phthalocyanine composition having a desired crystal type can be produced.

  In addition to the production method, a method of obtaining an oxytitanium phthalocyanine composition using 1,3-diiminoisoindoline and titanium tetrabutoxide as raw materials is generally performed. In addition, the oxytitanium phthalocyanine composition is subjected to an acid paste treatment or mechanical grinding treatment to obtain an amorphous oxytitanium phthalocyanine composition, and this is treated with a specific solvent, whereby a desired crystalline oxytitanium phthalocyanine composition is obtained. Can also be manufactured.

The phthalocyanine composition of the present invention may contain various phthalocyanine derivatives substituted with a substituent such as a chlorine atom, a fluorine atom, a nitro group, a cyano group, or a sulfonic acid group.
Moreover, you may use the phthalocyanine composition individually by 1 type mentioned above which concerns on this invention, or 2 types in mixture. Moreover, if the main component is the above-mentioned phthalocyanine composition according to the present invention, two or more types of pigments may be used by mixing a known pigment different from the above. The main component refers to a component having a content of 50% by mass or more based on the total amount of the charge generating material used. Examples of the charge generating substance to be mixed at this time include, for example, phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, benzimidazoles. Among these, phthalocyanine pigments or azo pigments are particularly preferable from the viewpoint of photosensitivity. When these pigments are used as the charge generation material, usually, fine particles of these pigments are used in the form of a dispersion layer bound with various binder resins.

  The phthalocyanine pigment can obtain a photosensitive member having high sensitivity to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm. Further, when an azo pigment such as monoazo, bisazo, or trisazo is used, white light, laser light having a wavelength around 660 nm, or relatively short wavelength laser light (for example, a wavelength in the range of 380 to 500 nm). A highly sensitive photoreceptor can be obtained. It is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region, and it is more preferable to use a phthalocyanine pigment in combination with a disazo pigment or a trisazo pigment.

  When the phthalocyanine pigment is mixed with the phthalocyanine composition, specifically, a metal-free phthalocyanine and a metal-containing phthalocyanine are used as the phthalocyanine pigment. Specific examples of metal-containing phthalocyanines include metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or their oxides, halides, hydroxides, alkoxides, and the like. Various crystal forms of phthalocyanines are used. In particular, D-type (also known as Y-type) oxytitanium phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, G-type, I-type, etc., which are highly sensitive crystal types [Mu] -oxo-gallium phthalocyanine dimer, [mu] -oxo-aluminum phthalocyanine dimer such as type II, and metal-free phthalocyanine are preferably used. Of these, D-type (Y-type) oxytitanium phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, G-type μ-oxo-gallium phthalocyanine dimer and the like are particularly preferable.

  However, in the case of mixing other pigments with the phthalocyanine composition according to the present invention, mixing at the time of the pigments and performing dry grinding together, followed by wet dispersion, the dispersibility is In some cases, the crystal form is greatly different or the crystal form cannot be maintained. In that case, it is preferable that the pigment to be mixed is dispersed separately and mixed with the photosensitive layer forming coating solution of the present invention at the time of the dispersion.

<Dry grinding>
In the present invention, the above-mentioned phthalocyanine composition is dry-ground. Dry means that no liquid is used and only a solid state. The grinding treatment using the dispersion medium can be performed by various apparatuses, but is usually performed using a paint shaker, a ball mill, a sand grind mill or the like, preferably a paint shaker or a ball mill, and particularly preferably a paint shaker. It is. The material of the media used for grinding may be any material as long as the media itself is not pulverized. However, when dry dispersion is performed continuously without separating the media after dry grinding. It is necessary to use a material that is insoluble in the coating solution for forming the photosensitive layer, does not react, and does not change in quality. Usually, beads, balls, and the like of glass, alumina, zirconia, stainless steel, ceramics, etc. are used. Of these, beads, balls of glass, zirconia, and ceramics are preferable, and glass beads are more preferable.

There are no particular limitations on the density and particle size of the media, but it is important to refine the size while maintaining the crystal form of the pigment to be ground. In grinding the phthalocyanine composition with a dry paint shaker, for example, the center particle size of the glass beads (particle size including 80% or more of the whole) is, from the viewpoint of productivity, the lower limit is usually 0.40 mm or more, Those having a thickness of preferably 0.50 mm or more, more preferably 0.60 mm or more are used. From the viewpoint of dispersibility, the upper limit is usually 8.00 mm or less, particularly 2.80 mm or less, more preferably 1.40 mm or less. In the case where continuous wet dispersion is performed without separating the media after dry grinding, it is necessary to select the density and particle size of the media in consideration of the wet dispersion apparatus.

  In dry grinding, the pigment is not completely amorphized, and the process is completed while maintaining the crystal form before grinding. If the crystal type changes, the electrical characteristics may be significantly deteriorated when the photosensitive member is formed. The D-type (also called Y-type) oxytitanium phthalocyanine composition is an example. When the D-type oxytitanium phthalocyanine composition is dry-ground, the crystal form cannot be maintained, and the sensitivity and dark decay are remarkable. Getting worse.

  The average particle size of the phthalocyanine composition after dry grinding is 10 μm or less. It is preferable to reduce the particle size of the phthalocyanine composition to near the final particle size of the photosensitive layer forming coating solution. Since the average particle size of the charge generating material dispersed in the coating solution for forming the photosensitive layer is usually 0.50 μm or less, the average particle size of the phthalocyanine composition after dry grinding is preferably 5 μm or less, more preferably 2 μm. Grind until the following: The average particle size is preferably as small as possible, but is usually larger than 0 and preferably 0.15 μm or more from the viewpoint of liquid stability during preparation of the coating liquid. The reason why the electrical characteristics are improved is not clear, but by reducing the particle size of the phthalocyanine composition to near the final particle size of the dispersion by dry grinding, the particles become more uniform and the surface area is increased. In addition, it can be presumed that the contact state with the solvent, binder resin, etc. makes the dispersion state with these easier to work, and it works favorably in charge generation, injection, charge retention, and the like.

  After completion of dry grinding, the media may be separated to isolate only the phthalocyanine composition, and wet dispersion may be performed by adding a new dispersion medium and solvent. It is preferable to carry out wet dispersion by adding a solvent without separating the media. If the media separation step is not performed, the productivity increases and the coating liquid can be more easily produced.

<Solvent used in coating solution for forming photosensitive layer>
The organic solvent used for the photosensitive layer forming coating solution of the present invention is not particularly limited as long as it dissolves the binder resin. For example, saturated aliphatic solvents such as pentane, hexane, octane and nonane, aromatic solvents such as toluene, xylene and anisole, halogenated aromatic solvents such as chlorobenzene, dichlorobenzene and chloronaphthalene, dimethylformamide, N- Amide solvents such as methyl-2-pyrrolidone, alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and benzyl alcohol, aliphatic polyhydric alcohols such as glycerin and polyethylene glycol, chains such as acetone, cyclohexanone and methyl ethyl ketone And cyclic ketone solvents, ether ketone solvents such as 4-methoxy-4-methyl-2-pentanone, ester solvents such as methyl formate, ethyl acetate, n-butyl acetate, methylene chloride, chloroform, 1,2- Dichloroeta Halogenated hydrocarbon solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve and other chain ether solvents, acetonitrile, dimethyl sulfoxide, sulfolane, hexamethyl Examples include aprotic polar solvents such as phosphoric acid triamide. Those which do not dissolve the undercoat layer described below are preferably used. These can be used alone or in combination of two or more.

<Binder resin used for coating solution for forming photosensitive layer>
The binder resin used in the photosensitive layer forming coating solution of the electrophotographic photoreceptor according to the present invention is not particularly limited as long as it is soluble in the organic solvent used in the photosensitive layer forming coating solution. Examples of binder resins include polyvinyl butyral resins, polyvinyl formal resins, polyvinyl acetal resins such as partially acetalized polyvinyl butyral resins partially modified with formal or acetal, polyarylate resins, polycarbonate resins, polyesters Resin, modified ether polyester resin, phenoxy resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polystyrene resin, acrylic resin, methacrylic resin, polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose resin, Polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride-vinyl acetate copolymer, hydroxy Vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers such as carboxyl-modified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, styrene-butadiene copolymers , Vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicon-alkyd resins, insulating resins such as phenol-formaldehyde resins, and organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinyl perylene. It can be selected from among them and used, but is not limited to these polymers. These binder resins may be used alone or in combination of two or more.

<Wet dispersion>
The phthalocyanine composition is dry-ground and then wet-dispersed to produce a photosensitive layer-forming coating solution. The photosensitive layer forming coating solution contains the phthalocyanine composition ground by the above-described dry dispersion, and the phthalocyanine composition is dispersed in the coating solution. In order to disperse the phthalocyanine composition in the coating solution, the above-mentioned organic solvent is used by using a known mechanical pulverizer such as a sand grind mill, a ball mill, a roll mill, an attritor, a paint shaker, or an ultrasonic oscillator. It can be produced by wet dispersion in the medium. Wet dispersion is dispersion using a liquid. From the viewpoint of dispersibility, a sand grind mill, a paint shaker, and an ultrasonic oscillator are preferable. During the dispersion of the phthalocyanine composition, other raw materials such as the other charge generation materials, the charge transport materials described later, the binder resin, and the additives described above may be simultaneously added and dispersed. The photosensitive layer forming coating solution may be prepared by dispersing or dissolving it and then mixing with the dispersion of the phthalocyanine composition.

  In wet dispersion of the phthalocyanine composition, it is preferable to disperse using a dispersion medium. Any material can be used as the material of the dispersion medium as long as the dispersion medium is not powdered. However, it is necessary to use a material that is insoluble in the coating solution solvent, does not react, and does not deteriorate. Uses beads, balls and the like of glass, alumina, zirconia, stainless steel, ceramics, etc. Among them, glass, zirconia, ceramic beads and balls are preferable, and glass beads are more preferable. There are no particular restrictions on the density and particle size of the dispersion medium. The use of the media used in the above-described dry grinding is more preferable because it is not necessary to separate from the phthalocyanine composition, and the production of the coating liquid becomes simpler.

Here, the dispersion index value (%) is used as an index value representing the dispersion state of the charge generating substance in the photosensitive layer forming coating solution. Here, the dispersion index value means an absorption intensity ratio (%) of 1000 nm with little absorption with respect to a wavelength near the maximum absorption of the pigment. A pigment is usually an aggregate (aggregate) of fine particle powders having a particle size of several tens of μm to several tens of nanometers. Dispersion is a particle interface by loosening aggregation of pigments as powder. It is stabilized so that a liquid such as an organic solvent penetrates and gets wet and is not aggregated again by a dispersant or a resin. As the dispersion progresses, the size of the aggregate of the pigment gradually decreases, and the number of pigment particles increases, but finally the particle diameter of the smallest unit is unraveled. By reducing the particle diameter of the aggregate, the ratio of reflection of light on the surface of the pigment particles is decreased, and the ratio of transmission is increased. That is, the change in the degree of dispersion in this way causes a change in light absorption probability due to a change in the number of particles, a change in light transmittance due to a change in the pigment aggregate particle diameter, and a change in light scattering degree on the pigment surface. The change will be prominent in the region with little absorption. Therefore, by comparing the intensity ratio with the maximum absorption wavelength region, in the case of the same kind of pigment, the relative state of dispersion can be compared. The dispersion index value of the coating solution is usually 4.0% or more, preferably 5.0% or more from the viewpoint of applicability, and is usually 25.0% or less, preferably 20.0% or less from the viewpoint of dispersibility. It is.

  The particle size of the charge generation material dispersed in the coating solution needs to be sufficiently small so as not to shield or scatter the exposure light, and the average particle size (cumulative 50% particle size) is 0.50 μm or less. The size is preferably reduced to 0.30 μm or less, more preferably 0.25 μm or less. Prior to wet dispersion, dry grinding is carried out in advance. Therefore, in wet dispersion, rather than reducing the particle size of the pigment, it is important to loosen the pigment, blend with the solvent, and prepare to the prescribed particle size. Become a role.

  Further, the solid content concentration and viscosity of the coating solution are preferably in the following ranges from the viewpoint of coating properties. Usually, it is 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less. Further, the viscosity of the coating solution is usually in the range of 0.1 mPa · s or more, preferably 0.5 mPa · s or more, and usually 20 mPa · s or less, preferably 10 mPa · s or less, at the temperature during use.

  In the charge generation layer of the function separation type photoreceptor, the blending ratio (mass) of the binder resin and the charge generation material is 10 parts by mass or more, preferably 30 parts by mass or more, with respect to 100 parts by mass of the binder resin. , 1000 parts by mass or less, preferably 500 parts by mass or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material. On the other hand, if the ratio of the charge generating substance is too low, the sensitivity as a photoreceptor may be reduced. The film thickness of the charge generation layer is usually 0.1 μm or more, preferably 0.15 μm or more, and 10 μm or less, preferably 0.6 μm or less. For the charge generation layer, known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, dispersion aids for improving dispersibility, coatability May contain a leveling agent, a surfactant, silicone oil, fluorine-based oil, and other additives for improving the viscosity.

  In the case of a single-layer type photoreceptor, the charge generation material is dispersed in a matrix mainly composed of a binder resin and a charge transport material having the same mixing ratio as that of the charge transport layer described later. If the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained, and if it is too large, the chargeability and sensitivity may be reduced. % Or more, preferably 5% by mass or more, and 50% by mass or less, preferably 45% by mass or less. The film thickness of the photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less. In addition, single layer type photoreceptors are also known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, and dispersion aids for improving dispersibility. Agents, leveling agents for improving coating properties, surfactants, silicone oils, fluorine oils, and other additives may be contained.

[Method of forming photosensitive layer using the coating solution]
Using the coating solution produced as described above, this is coated on a conductive support (or an undercoat layer when an undercoat layer is provided) and dried to form a photosensitive layer.
Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used. Among them, the dip coating method, the spray coating method, and the wire bar coating method are preferable, and the dip coating method is particularly preferable.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.

[Electrophotographic photoreceptor]
<Conductive support>
As the conductive support used for the photoreceptor, for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powders such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. As a form, a drum shape, a sheet shape, a belt shape or the like is used. A conductive material having an appropriate resistance value may be applied to a conductive support of a metal material in order to control conductivity, surface properties, etc., or to cover defects.

When a metal material such as an aluminum alloy is used as the conductive support, it is preferable to use an anodized film as a blocking layer in order to prevent image black spots and fogging due to leakage from the substrate. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The support surface may be smooth, or may be roughened by using a special cutting method or polishing. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support.

<Underlayer>
An undercoat layer is preferably provided as a blocking layer between the conductive support and the photosensitive layer described below for the purpose of improving adhesiveness and blocking properties. As the undercoat layer, a resin, a resin in which particles such as a metal oxide are dispersed, or the like is used. These may be used alone or in combination with particles of several resins, metal oxides and the like.

  Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.

In addition, various particle sizes of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is usually 1 nm or more, preferably 10 nm or more, and usually 100 nm or less. Preferably it is 50 nm or less.
The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. As binder resin used for the undercoat layer, epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, Known binder resins such as polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin and the like can be mentioned. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

Although the use ratio of the inorganic particles to the resin can be arbitrarily selected, it is usually preferably used in the range of 10% by mass or more and 500% by mass or less from the viewpoint of the stability of the dispersion and coating properties.
The thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photosensitive member. Therefore, it is usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.25 μm or more, further preferably 0.5 μm or more, and particularly preferably 0.75 μm or more. Moreover, it is 30 micrometers or less normally, Preferably it is 20 micrometers or less. A known antioxidant or the like may be mixed in the undercoat layer. The undercoat layer may contain pigment particles, resin particles and the like for the purpose of preventing image defects.

<Photosensitive layer>
When the photosensitive layer has a blocking layer such as the above-described undercoat layer on the conductive support, it is formed thereon. As a type of the photosensitive layer, a layered structure composed of two or more layers including a charge generation layer in which a charge generation material is dispersed in a binder resin and a charge transport layer in which a charge transport material is dispersed in a binder resin. There are many function-separated types (hereinafter referred to as “laminated photosensitive layer” as appropriate), and among them, there are many “sequentially laminated photosensitive layers” in which a charge generation layer and a charge transport layer are laminated in this order from the conductive support side. Adopted. A “sequentially laminated photosensitive layer” can exhibit balanced photoconductivity. Other types of photosensitive layers that can be employed include a “single-layer type photosensitive layer” that includes a charge generation material, a charge transport material, and a binder resin in a single layer.

<Charge transport layer>
<Binder resin>
For the charge transport layer, a binder resin is used to ensure film strength. The charge transport layer can be obtained by applying and drying a coating solution obtained by dissolving or dispersing a charge transport material and various binder resins in a solvent. Examples of the binder resin include polymers and copolymers of vinyl compounds such as butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylic ester resin, methacrylic ester resin, vinyl alcohol resin, ethyl vinyl ether, and polyvinyl butyral. Resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyarylate resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicone resin, silicon-alkyd resin, poly-N-vinylcarbazole resin, etc. Is given. These resins may be modified with a silicon reagent or the like. Of the binder resins, polycarbonate resin or polyarylate resin is particularly preferable.

  These can also be used by crosslinking with an appropriate curing agent by heat, light or the like. Also, two or more kinds of binder resins can be blended and used. The viscosity average molecular weight of the polycarbonate resin and the polyarylate resin is not particularly limited, but is usually 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, provided that it is usually 300,000 or less. Preferably it is 200,000 or less, More preferably, it is 100,000 or less. If the viscosity average molecular weight is excessively small, the mechanical strength of the photosensitive layer is lowered, which is not practical. On the other hand, if the viscosity average molecular weight is excessively large, it is difficult to apply and form the photosensitive layer to an appropriate film thickness.

<Charge transport material>
The charge transport material is not particularly limited, and any material can be used. Examples of known charge transport materials include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron withdrawing materials such as quinone compounds such as diphenoquinone, and carbazole derivatives. , Indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and a plurality of these compounds Examples thereof include an electron donating substance such as a polymer in which a species is bonded, or a polymer having a group composed of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable.

Any one of these charge transport materials may be used alone, or two or more thereof may be used in any combination.
Preferred specific examples of the charge transport material are shown below. In the following compounds, R represents the same or different substituents. Specifically, a hydrogen atom, an alkyl group, an alkoxy group, a phenyl group, an arylalkyl and the like are preferable. Particularly preferred is a methyl group, an ethyl group, a methoxy group or a benzyl group. N is an integer of 0 or more and 2 or less.

  The following exemplary compounds are specific examples of charge transport materials that can be used, and are not limited thereto.

<Formation method>
The ratio of the binder resin to the charge transport material is usually 10 parts by mass or more with respect to 100 parts by mass of the binder resin, and preferably 30 parts by mass or more from the viewpoint of reducing the residual potential. From a viewpoint, 35 mass parts or more is more preferable. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, it is usually 150 parts by mass or less, preferably 120 parts by mass or less from the viewpoint of compatibility between the charge transport material and the binder resin, and from the viewpoint of printing durability. 100 mass parts or less are more preferable, and 80 mass parts or less are especially preferable from a viewpoint of scratch resistance.

In the case of a multilayer photoreceptor, the thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, and usually 50 μm or less from the viewpoint of long life, image stability, and high resolution. , Preferably 45 μm or less, more preferably 40 μm or less.
It should be noted that each layer constituting the laminated type has a well-known antioxidant, plasticizer, UV absorption for the purpose of improving film forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc. An agent, an electron-withdrawing compound, a leveling agent, a visible light shielding agent, and the like may be included.
Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of the leveling agent include silicone oil and fluorine oil.

<Other functional layers>
In the order laminated type photoreceptor, a protective layer may be provided on the outermost layer for the purpose of preventing the photosensitive layer from being worn and preventing or reducing the deterioration of the photosensitive layer due to a discharge substance or the like generated from a charger or the like. The protective layer is formed by containing a conductive material in an appropriate binder resin, or charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and JP-A-10-252377. The copolymer using the compound which has can be used.

Examples of the conductive material used for the protective layer include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, and oxide. Metal oxides such as titanium, tin oxide-antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto.
As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, and siloxane resin can be used. Also, a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and a copolymer of the above resin can be used.

  Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of a fluororesin, silicone resin, polyethylene resin, or the like. You may contain the particle | grains which consist of these resin, and the particle | grains of an inorganic compound. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.

<Method for forming each layer>
Each layer constituting the above-described photoreceptor is formed by immersing, spraying, nozzle coating, wire bar coating, roller coating, a coating solution obtained by dissolving or dispersing a substance to be contained in a solvent on a conductive support. It is formed by repeating a coating / drying step sequentially for each layer by a known method such as blade coating.

  There are no particular restrictions on the solvent or dispersion medium used for the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, acetone, methyl ethyl ketone, cyclohexanone, ketones such as 4-methoxy-4-methyl-2-pentanone, aromatic hydrocarbons such as benzene, toluene, xylene, dichloromethane, Chlorinated hydrocarbons such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, Diethyl Min, triethanolamine, ethylenediamine, nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methyl-2-pyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

The amount of the solvent or the dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriately determined so that the physical properties such as the solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
For example, in the case of the charge transport layer, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less, preferably 35% by mass or less. Further, the viscosity of the coating solution is usually 10 mPa · s or higher, preferably 50 mPa · s or higher, and usually 2000 mPa · s or lower, preferably 1000 mPa · s or lower, at the temperature during use.

Each layer constituting these photoconductors is formed by applying the coating solution obtained by the above-described method on a support using a known coating method, repeating the coating and drying steps for each layer, and sequentially coating the layers. The Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used. Of these, dip coating, spray coating, and wire bar coating are preferred, and dip coating is more preferred.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.

[Cartridge, image forming device]
Next, a drum cartridge and an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.
As shown in FIG. 1, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further includes a transfer device 5, a cleaning device 6, and a fixing device as necessary. 7 is provided.

  In FIG. 1, reference numeral 1 denotes a drum-shaped photoconductor which is driven to rotate at a predetermined peripheral speed in the direction of an arrow about an axis. The photosensitive member 1 is uniformly charged with a positive or negative predetermined potential on the surface thereof by the charging device 2 during the rotation process, and then exposure for forming a latent image is performed by the image exposure unit in the exposure device 3. The formed electrostatic latent image is then developed with toner by the developing device 4, and the toner developed image is sequentially transferred onto a transfer body (paper or the like) P fed from the paper feeding unit by the corona transfer device 5. . The image-transferred transfer body is then sent to the fixing device 7 where the image is fixed and printed out of the apparatus. The toner remaining after the transfer is removed by the cleaning device 6 on the surface of the photoreceptor 1 after the image transfer. Further, in addition to the above configuration, a configuration capable of performing the static elimination process may be used.

The electrophotographic photosensitive member 1 is not particularly limited as long as it is the above-described electrophotographic photosensitive member of the present invention. In FIG. 1, as an example, the above-described photosensitive layer forming coating solution is applied onto a cylindrical conductive support. 2 shows a drum-shaped electrophotographic photosensitive member formed.
The charging device 2 charges the electrophotographic photoreceptor 1 and uniformly charges the surface of the electrophotographic photoreceptor 1 to a predetermined potential. Although FIG. 1 shows a roller-type charging device (charging roller), other than this, a charging brush, a corona charging device such as a corotron and a scorotron are often used. Examples of direct charging means for charging a direct charging member to which a voltage is applied by contacting the surface of the photoreceptor include a contact charger such as a charging roller or a charging brush. As the direct charging means, any one that involves air discharge or injection charging that does not involve air discharge is possible. In addition, as a voltage applied at the time of charging, in the case of only a direct current voltage, an alternating current can be superimposed on a direct current.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Halogen lamps, fluorescent lamps, lasers (semiconductors, He—Ne), LEDs, photoconductor internal exposure systems, and the like are used. As digital electrophotographic systems, it is preferable to use lasers, LEDs, optical shutter arrays, and the like. As the wavelength, monochromatic light with a wavelength of 780 nm, monochromatic light with a slightly shorter wavelength in the region of 600 to 700 nm, monochromatic light with a short wavelength of 380 to 600 nm, and the like can be used.

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, two-component magnetic brush development, or a wet development method is used. Can do. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and is configured to store toner T inside the developing tank 41. Further, a replenishing device that replenishes toner T may be attached to the developing device 4 as necessary. This replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

  As the toner T, chemical toners such as suspension granulation, suspension polymerization, and emulsion polymerization aggregation can be used in addition to the pulverized toner. In particular, in the case of chemical toners, those having a small particle diameter of about 4 to 8 μm are used, and those having a shape close to a sphere, and those outside a potato-like sphere can also be used. The polymerized toner is excellent in charging uniformity and transferability, and is preferably used for high image quality.

The type of the transfer device 5 is not particularly limited, and a device using an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, an adhesive transfer method, or the like can be used. FIG. 1 shows, as an example, a diagram in which a transfer device 5 including a transfer charger, a transfer roller, a transfer belt, and the like is disposed to face the electrophotographic photosensitive member 1.
The type of the fixing device 7 is not particularly limited, and an apparatus using an arbitrary system such as heat roller fixing, flash fixing, oven fixing, pressure fixing, IH fixing, belt fixing, IHF fixing, or the like can be used. These fixing methods may be used alone or in combination with a plurality of fixing methods. In FIG. 1, an upper fixing member (pressure roller) 71 and a lower fixing member (fixing roller) 72 are shown as an example. Inside these, a heating device 73 is provided. When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is overheated to a molten state, cooled after passing, and then the toner is transferred onto the recording paper. Is established.

  The type of the cleaning device 6 is not particularly limited, and any cleaning device such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, or a blade cleaner is used. The cleaning device 6 removes the residual toner adhering to the photosensitive member 1, but the cleaning device 6 may be omitted if the amount of toner remaining on the surface of the photosensitive member is small.

The neutralization step is a step of performing neutralization of the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and is often omitted, but when used, fluorescent lamps, LEDs, etc. are used, In many cases, the intensity of exposure energy is three times or more that of exposure light.
In addition to these processes, the image forming apparatus may have a pre-exposure process and an auxiliary charging process.

In the present invention, a plurality of components such as the drum-shaped photosensitive member 1, the charging unit 2, the developing unit 4 and the cleaning unit 6 are integrally combined as a drum cartridge, and the drum cartridge is copied. It may be configured to be detachable from the main body of an electrophotographic apparatus such as a machine or a laser beam printer. For example, at least one of the charging unit 2, the developing unit 4, and the cleaning unit 6 can be integrally supported together with the drum-shaped photoreceptor 1 to form a cartridge.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. In addition, the following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples unless it is contrary to the gist thereof.

[Example 1]
<Method for creating photoreceptor sheet>
The undercoat layer dispersion was prepared as follows. A surface-treated titanium oxide obtained by treating rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) with 3% by mass of methyldimethoxysilane with respect to the titanium oxide is used as a ball mill of methanol / 1-propanol. To obtain a dispersion slurry of hydrophobized titanium oxide. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula ( Compound represented by B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula The compound represented by (E)] has a composition molar ratio of 60% / 15% / 5% / 15% / 5% and is agitated and mixed with pellets of copolymerized polyamide to dissolve the polyamide pellets. Then, ultrasonic dispersion treatment is performed, so that the mass ratio of methanol / 1-propanol / toluene is 7/1/2, and the hydrophobically treated titanium oxide / copolymerized polyamid. Which contained a weight ratio 3/1 was undercoat layer dispersion having a solid concentration of 18.0%.

The coating solution for forming the undercoat layer thus obtained was applied onto a polyethylene terephthalate sheet (thickness 75 μm) vapor-deposited on the surface using a bar coater, dried, and the film thickness after drying was 1 A subbing layer of 25 μm was provided.
Next, the charge generation layer forming coating solution was prepared as follows. The oxytitanium phthalocyanine composition produced by the same method as in Example 1 of Japanese Patent No. 4941345 has a Bragg angle (2θ ± 0.2 °) of 9.3 °, 10.3 in the powder X-ray diffraction spectrum by CuKα characteristics. Main diffraction peaks were shown at 5 °, 13.2 °, 15.1 ° and 26.2 °. The powder X-ray diffraction spectrum is shown in FIG. 15 parts by mass of this oxytitanium phthalocyanine composition together with 155 parts by mass of glass beads (GB502M manufactured by Potters Barotini) having a central particle size (particle size containing 80% or more) of 1.0 to 1.4 mm Shake for 2 hours to dry grind. Thereafter, 390 parts by mass of glass beads were further added, 210 parts by mass of 1,2-dimethoxyethane was added, and wet dispersion was performed for 0.5 hour in a sand grind mill to prepare a pigment dispersion. 225 parts by mass of the pigment dispersion thus obtained was added to 150 parts by mass of a 5% by mass 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.). 1,2-Dimethoxyethane was added to finally prepare a coating solution for forming a charge generation layer having a solid content concentration of 4.0% by mass. The charge generation layer forming coating solution thus obtained was applied onto the undercoat layer using a bar coater, dried, and the film thickness after drying was 0.4 μm (0.40 g / m ² ) The charge generation layer was formed.

  The charge generation layer forming coating solution was applied on a non-reflective cover glass so that the film thickness after drying was 10 μm or more, dried at room temperature, and a thin film X-ray diffraction spectrum by CuKα characteristics was measured. This thin film X-ray diffraction spectrum shows main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 9.3 °, 13.2 ° and 26.2 °, and maintains the crystal form of the charge generating material used. It was. The thin film X-ray diffraction spectrum is shown in FIG.

  Subsequently, as a charge transport material, 56 parts by mass of CTM (1) represented by the following structural formula and 14 parts by mass of CTM (2) are used, and a polycarbonate resin 100 having a repeating structure of the following PCR (1) is used as a binder resin. 8 parts by weight of the antioxidant (1) represented by the following structural formula is used as the antioxidant, 0.03 parts by weight of silicone oil is used as the leveling agent, and these are combined with tetrahydrofuran and toluene. A charge transport layer forming coating solution was prepared by mixing with 640 parts by mass of a mixed solvent (tetrahydrofuran 80% by mass, toluene 20% by mass). This charge transport layer forming coating solution was applied onto the above-described charge generation layer so that the film thickness after drying was 20 μm, and dried to obtain a photoreceptor sheet having a laminated photosensitive layer. This electrophotographic photosensitive member is designated as 1A.

[Comparative Example 1]
15 parts by mass of the oxytitanium phthalocyanine composition used in Example 1, 210 parts by mass of 1,2-dimethoxyethane, and glass beads having a central particle size of 0.60 mm to 0.85 mm (GB200M manufactured by Potters Barotini) 580 A part by mass was added and dispersed for 3 hours with a sand grind mill to obtain a pigment dispersion. Otherwise, the procedure of Example 1 was followed to fabricate an electrophotographic photoreceptor 1B.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Example 2]
In place of the oxytitanium phthalocyanine composition used in Example 1, the same method as in Example 1 of Japanese Patent No. 4941345, except that N-methyl-2-pyrrolidone was heated and stirred at 140 to 150 ° C. three times. In the powder X-ray diffraction spectrum by CuKα characteristic, which was manufactured by repeating hot water washing and methanol washing twice, Bragg angle (2θ ± 0.2 °) 9.3 °, 10.5 °, 13. An oxytitanium phthalocyanine composition showing main diffraction peaks at 2 °, 15.1 ° and 26.2 ° was used. Other than that was carried out similarly to Example 1, and produced the electrophotographic photoreceptor 2A.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Comparative Example 2]
An electrophotographic photoreceptor 2B was produced in the same manner as in Comparative Example 1 except that the oxytitanium phthalocyanine composition used in Example 2 was used instead of the oxyphthalocyanine composition used in Comparative Example 1.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Example 3]
In place of the oxytitanium phthalocyanine composition used in Example 1, the same method as in Example 1 of Japanese Patent No. 4941345 is used, but the product after the reaction was hot filtered at 130 ° C., and then N-methyl- Washed with 2-pyrrolidone and methanol, N-methyl-2-pyrrolidone heated and stirred at 140-150 ° C. three times, hot water and methanol twice washed, powder with CuKα characteristics Oxytitanium phthalocyanine showing main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 9.3 °, 10.5 °, 13.2 °, 15.1 ° and 26.2 ° in the X-ray diffraction spectrum The composition was used. Other than that was carried out similarly to Example 1, and produced the electrophotographic photoreceptor 3A.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Example 4]
Using the oxytitanium phthalocyanine used in Example 3 instead of the oxytitanium phthalocyanine composition used in Example 1, the dry grinding time on the paint shaker was changed from 2 hours to 30 minutes, An electrophotographic photoreceptor 4A was produced in the same manner as in Example 1 except that the wet dispersion was changed from 0.5 hour to 2 hours.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Comparative Example 3]
Using the oxytitanium phthalocyanine used in Example 3 instead of the oxytitanium phthalocyanine composition used in Example 1, the dry grinding time in the paint shaker was changed from 2 hours to 2 minutes, An electrophotographic photoreceptor 3B was produced in the same manner as in Example 1 except that the wet dispersion was changed from 0.5 hour to 4 hours.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Comparative Example 4]
An electrophotographic photoreceptor 4B was produced in the same manner as in Comparative Example 1 except that the oxytitanium phthalocyanine composition used in Example 3 was used instead of the oxytitanium phthalocyanine composition used in Comparative Example 1.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Example 5]
Instead of the oxytitanium phthalocyanine composition used in Example 1, in the powder X-ray diffraction spectrum by CuKα characteristics produced by the same method as in Production Example 1 of JP-B-5-31137, the Bragg angle (2θ ± 0 .2 °) 9.3 °, 10.5 °, 13.2 °, 1
An oxytitanium phthalocyanine composition showing main diffraction peaks at 5.1 ° and 26.2 ° was used. Other than that was carried out similarly to Example 1, and produced the electrophotographic photoreceptor 5A.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Comparative Example 5]
Instead of the oxyphthalocyanine composition used in Comparative Example 1, the oxytitanium phthalocyanine composition used in Example 5 was used and the dispersion time of the sand grind mill was changed to 4 hours. Thus, an electrophotographic photoreceptor 5B was produced.
Further, when the thin film X-ray diffraction spectrum of the charge generation layer forming coating solution was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 3 was obtained, and the crystal form of the charge generation material used was maintained. It was.

[Example 6]
Instead of the oxytitanium phthalocyanine composition used in Example 1, a B-type oxytitanium phthalocyanine composition produced by the method described in Production Example 1 of Japanese Patent No. 4887716 was used. This B-type oxytitanium phthalocyanine has a Bragg angle (2θ ± 0.2 °) of 7.6 °, 10.3 °, 22.5 °, 24.2 °, 25.25 in a powder X-ray diffraction spectrum by CuKα characteristics. This is an oxytitanium phthalocyanine composition showing main diffraction peaks at 4 ° and 28.6 °, and this powder X-ray diffraction spectrum is shown in FIG. Other than that was carried out similarly to Example 1, and produced the electrophotographic photoreceptor 6A.
Further, when the thin film X-ray diffraction spectrum of the coating solution for forming the charge generation layer was measured in the same manner as in Example 1, the Bragg angle (2θ ± 0.2 °) was 7.6 °, 22.5 °, 24. Main diffraction peaks were shown at 2 °, 25.4 ° and 28.6 °, and the crystal form of the charge generating material used was maintained. The thin film X-ray diffraction spectrum is shown in FIG.

[Example 7]
Using the oxytitanium phthalocyanine used in Example 6 instead of the oxytitanium phthalocyanine composition used in Example 1, the dry grinding time on the paint shaker was changed from 2 hours to 30 minutes, An electrophotographic photoreceptor 7A was produced in the same manner as in Example 1 except that the wet dispersion was changed from 0.5 hour to 2 hours.

Further, when the thin film X-ray diffraction spectrum of the coating solution for forming the charge generation layer was measured in the same manner as in Example 1, the same spectrum as in FIG. 5 was obtained, and the crystal form of the used charge generation material was maintained. It was.
[Comparative Example 6]
Using the oxytitanium phthalocyanine used in Example 6 instead of the oxytitanium phthalocyanine composition used in Example 1, the dry grinding time in the paint shaker was changed from 2 hours to 2 minutes, An electrophotographic photoreceptor 6B was produced in the same manner as in Example 1 except that the wet dispersion was changed from 0.5 hours to 4 hours.
Further, when the thin film X-ray diffraction spectrum of the coating solution for forming the charge generation layer was measured in the same manner as in Example 1, the same spectrum as in FIG. 5 was obtained, and the crystal form of the used charge generation material was maintained. It was.

[Comparative Example 7]
Instead of the oxyphthalocyanine composition used in Comparative Example 1, the oxytitanium phthalocyanine composition used in Example 6 was used and the dispersion time of the sand grind mill was changed to 4 hours. Thus, an electrophotographic photoreceptor 7B was produced.
Further, when the thin film X-ray diffraction spectrum of the coating solution for forming the charge generation layer was measured in the same manner as in Example 1, the same spectrum as in FIG. 5 was obtained, and the crystal form of the used charge generation material was maintained. It was.

[Comparative Example 8]
Instead of the oxytitanium phthalocyanine composition used in Example 1, a D-type (also called Y-type) oxytitanium phthalocyanine composition produced by the method described in Production Example 1 of Japanese Patent No. 4887716 was used. This D-type oxytitanium phthalocyanine exhibits a strong diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in a powder X-ray diffraction spectrum by CuKα characteristics. The powder X-ray spectrum is shown in FIG. Other than that was carried out similarly to Example 1, and produced the electrophotographic photoreceptor 8B.

  Further, when the thin film X-ray diffraction spectrum of the coating solution for forming a charge generation layer was measured in the same manner as in Example 1, the Bragg angles (2θ ± 0.2 °) were 9.3 °, 13.2 ° and 26.26. The main diffraction peak was shown at 2 °, and the crystal form of the charge generating material used was not maintained. The thin film X-ray diffraction spectrum is shown in FIG.

[Comparative Example 9]
Instead of the oxyphthalocyanine composition used in Comparative Example 1, the oxytitanium phthalocyanine composition used in Comparative Example 6 was used and the dispersion time of the sand grind mill was changed to 1 hour. Thus, an electrophotographic photoreceptor 9B was produced.
Further, when a thin film X-ray diffraction spectrum of the coating solution for forming a charge generation layer was measured in the same manner as in Example 1, it showed a main diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° and was used. The crystal form of the generated charge generating material was maintained. The thin film X-ray diffraction spectrum is shown in FIG.

[Comparative Example 10]
Instead of the oxytitanium phthalocyanine composition used in Example 1, a D-type (also called Y-type) oxytitanium phthalocyanine composition produced by the method described in Comparative Production Example 1 of Japanese Patent No. 4887716 was used. This D-type oxytitanium phthalocyanine exhibits a strong diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in a powder X-ray diffraction spectrum by CuKα characteristics. Other than that was carried out similarly to Example 1, and produced the electrophotographic photoreceptor 10B.
Further, when the thin film X-ray diffraction spectrum of the coating solution for forming the charge generation layer was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 7 was obtained, and the crystal form of the used charge generation material was maintained. There wasn't.

[Comparative Example 11]
Instead of the oxyphthalocyanine composition used in Comparative Example 1, the oxytitanium phthalocyanine composition used in Comparative Example 10 was used and the dispersion time of the sand grind mill was changed to 1 hour. Thus, an electrophotographic photoreceptor 11B was produced.
Further, when the thin film X-ray diffraction spectrum of the coating solution for forming the charge generation layer was measured in the same manner as in Example 1, a spectrum similar to that in FIG. 8 was obtained, and the crystal form of the used charge generation material was maintained. It was.

<Liquid measurement of photosensitive layer forming coating solution>
The dispersion index value and the particle size distribution of the coating solution for forming the charge generation layer used when producing the photoreceptors 1A to 7A and 1B to 11B were measured.
Regarding the measurement and calculation method of the dispersion index value, an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-1650PC) is used, and the coating solution for forming the charge generation layer is reduced to a level that does not exceed the measurement limit of the detector. After dilution with dimethoxyethane, the absorbance from 400 nm to 1000 nm was measured using a 10 mm quartz cell, and the ratio of the absorbance at 1000 nm to the maximum absorbance was calculated as the dispersion index value. By comparing these values, the dispersion state of the coating liquid can be relatively compared.

For the particle size distribution, a particle size distribution meter (manufactured by Nikkiso Co., Ltd., trade name: Nanotrac UPA-EX150) is used, and the coating solution for forming the charge generation layer is 1,2-dimethoxysilane so as not to exceed the measurement limit of the detector. Diluted and measured at 25 ° C. Cumulative curve is determined with the total volume of particles being 100%. When the cumulative curve is determined with the total volume of particles being 100%, the particle diameter at the point where the cumulative curve is 10% is defined as the cumulative particle diameter of 10%. The particle diameter at the point where the 50% was reached was the cumulative 50% particle diameter (average particle diameter), and the particle diameter where the cumulative curve was 90% was the cumulative 90% particle diameter. Table 1 shows the measurement results of the liquidity of the charge generation layer forming coating solution.

From the results shown in Table 1, the dispersion index value is in the range of 5.6% to 15.5%, and a liquid that does not cause a problem when applied can be prepared. Comparing the results of the liquids using the same charge generating material, the difference in dispersion index value is not so large, and Example 2 and Comparative Example 2 having the largest difference are 4.9%. Further, even when the cumulative 50% particle diameter (average particle diameter) falls within the range of 0.155 μm to 0.229 μm, the difference in the cumulative 50% particle diameter is not so large when compared with the result of the liquid using the same charge generating substance. The difference between Example 4 and Comparative Example 4 having the largest difference is 0.046 μm. From these results, even if the presence or absence of the dry-type grinding treatment and the treatment time are different, by adjusting the dispersion time, the amount of beads, etc., the dispersion index value and the particle size having no problem in the dispersion state are about the same. It can be said that a coating solution for forming a charge generation layer having liquidity could be prepared. Since the liquidity is almost the same, it is not necessary to consider the difference in electrical characteristics derived from the liquidity, and the electrical characteristics can be directly compared.

<Measurement of particle size after dry grinding>
Regarding the oxytitanium phthalocyanine composition described in Examples 3, 5 and 6, when the dry grinding was completed, the oxytitanium phthalocyanine composition was taken out, and the particle size was measured by a particle size distribution meter (trade name, manufactured by Nikkiso Co., Ltd.). : Measured at 25 ° C. using Nanotrac UPA-EX150). The sample was prepared by adding 11.0 g of 1,2-dimethoxyethane to 0.5 g of oxytitanium phthalocyanine and a 7 mass% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.). 2.0 g was added and handshaked to obtain a dispersion. This dispersion was diluted with 1,2-dimethoxyethane to the extent that the measurement limit of the detector was not exceeded and used for measurement. The measurement results of the particle size distribution are shown in Table-2.

  From the results of Table 2 above, the cumulative 50% particle size after 2 hours of dry grinding was as small as 0.86-1.37 μm. When the oxytitanium phthalocyanine composition before the grinding treatment is observed with a scanning electron microscope (SEM), the particle diameters of the oxytitanium phthalocyanine composition produced by any of the manufacturing methods vary widely, and there are particles of about several μm to 100 μm. On average, there were many secondary particles with a size of about 20 to 50 μm. Considering that the cumulative 50% particle size of the dispersion after wet dispersion is 0.173 to 0.223 μm from the results of Table 1, the final treatment is performed after 2 hours of dry grinding. It can be said that it is ground to a place close to the particle size of the dispersion liquid.

  The oxytitanium phthalocyanine composition having a dry grinding treatment time shorter than 2 hours was also tried to be measured with the particle size distribution meter, but did not fall within the measurement range (upper limit 10 μm) of the particle size distribution meter. The pigment particles settled, and measurement with the same equipment and method was not possible. Therefore, the oxytitanium phthalocyanine composition is directly observed with a scanning electron microscope (SEM), the lengths in the major axis direction of a plurality (at least 10 or more) of particles are measured, and the average value is calculated as the average particle size. did. Table 3 shows the average particle diameter determined from SEM observation after the dry grinding treatment.

  From the results in Table 3 above, the average particle diameter varies depending on the dry grinding time, and the oxytitanium phthalocyanine composition described in Examples 4 and 7 is 10 μm or less after 30 minutes of dry grinding, It was confirmed that the oxytitanium phthalocyanine compositions described in Comparative Examples 3 and 6 had an average particle size of greater than 10 μm after 2 minutes of dry grinding.

<Evaluation of electrical characteristics of photoconductor>
The photoconductors 1A to 9A and 1B are prepared using an electrophotographic characteristic evaluation apparatus (in accordance with the electrophotographic technology basics and applications, edited by the Electrophotographic Society, Corona, page 404-405) prepared according to the electrophotographic society measurement standard. ˜9B was affixed to an aluminum drum, the drum was rotated at a constant rotational speed, and an electrical property evaluation test was performed by a cycle of charging, exposure, potential measurement, and static elimination.

The initial surface potential was set to −700 V, monochromatic light of 780 nm for exposure and 660 nm for charge removal was used. The exposure energy when exposed to light of 780 nm and the surface potential becomes −350 V (half exposure energy) is measured as 1/2 sensitivity (E1 / 2) (μJ / cm ² ), and the surface potential is −
The irradiation energy (half exposure energy) at 140 V was measured as 1/5 sensitivity (E1 / 5) (μJ / cm ² ). The smaller the sensitivity, the better the electrical characteristics. Further, the surface potential after 5 seconds charged to −700 V was measured, and the retention rate was defined as dark decay (DDR) (%). Larger dark decay indicates better charge retention and better performance. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%. The evaluation results of electrical characteristics are shown in Table-4.

From the results of Table 4 above, when the same oxytitanium phthalocyanine composition is used and the dry grinding processing time is 2 hours or 30 minutes and the photosensitive body without dry grinding are compared (photosensitive Photoreceptor 1A and photoreceptor 1B, photoreceptor 2A and photoreceptor 2B, photoreceptors 3A and 4A and photoreceptor 4B, photoreceptor 5A and photoreceptor 5B, photoreceptors 6A and 7A and photoreceptor 6B) photoreceptor with dry grinding A had better 1/2 sensitivity, 1/5 sensitivity, and dark attenuation than Photoconductor B without dry grinding. Further, when comparing the photosensitive member having a dry grinding process time of 2 hours and the photosensitive member of 30 minutes (photosensitive member 3A and photosensitive member 4A, photosensitive member 6A and photosensitive member 7A), the photosensitive member having a processing time of 2 hours is compared. However, the half sensitivity, the 1/5 sensitivity, and the dark decay were all better than the photoreceptor of 30 minutes. However, when a photoconductor for 2 minutes of dry grinding is compared with a photoconductor for 30 minutes and a photoconductor without dry grinding (photoconductor 3B and photoconductors 4A and 4B, photoconductor 6B and photoconductor 7A). 7B) The treatment time of 2 minutes was further worse than the case of 30 minutes, with 1/2 sensitivity, 1/5 sensitivity and dark decay being worse, and the result was worse than without dry grinding. As described above, although the dispersion index value and the particle size distribution of the coating solution for forming the photosensitive layer are almost the same, the result of the electrical characteristics shows that the photoconductor is improved for 30 minutes by dry grinding treatment for 2 hours. Clearly, the effect of dry grinding is evident. Despite using the same composition and the same liquid coating solution, a dry grinding process of 30 minutes and 2 hours is more sensitive and dark decaying than a photoreceptor with only wet dispersion without dry grinding. The reason why the electrical properties are improved is not clear, but the oxytitanium phthalocyanine composition alone is ground in advance and then contacted with the solvent, binder resin, etc., the dispersion state with these becomes easier to adapt, and charge generation I guess it works in favor of injection. The shorter the dry grinding treatment time, the larger the particle size. Therefore, the compatibility with the solvent and the binder resin worsens, the effect of dry grinding in advance decreases, and the electrical characteristics deteriorate. When the dry grinding treatment time is short and the average particle size is larger than 10 μm, the effect of dry grinding is not seen, and the electrical characteristics are worse than those obtained by wet dispersion alone. That is, when the particle size is large and is 10 μm or more, it is easier for the material to disperse with the binder and solvent from the beginning, which is advantageous for charge generation and injection. Therefore, it is important to improve the sensitivity and dark decay by grinding the oxytitanium phthalocyanine composition to a particle size of 10 μm or less.

  In Comparative Examples 8, 9, 10 and 11, a D-type (also called Y-type) oxytitanium phthalocyanine composition showing a strong diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in a powder X-ray diffraction spectrum It was used. Comparing Photoreceptor 8B and Photoreceptor 9B, and Photoreceptor 10B and Photoreceptor 11B, which use the same oxytitanium phthalocyanine composition and differ in the presence or absence of dry grinding, Photosensitive A with dry grinding is dry-polished. Compared with the photoreceptor B without crushing, the 1/2 sensitivity, 1/5 sensitivity, and dark decay all deteriorated. This deterioration of the electrical characteristics is caused by the fact that the D-type oxytitanium phthalocyanine composition cannot maintain its crystal form by dry grinding, and a part of the D-type crystal has been transferred to the A type in the coating solution. Therefore, it is the oxytitanium phthalocyanine composition having a specific crystal type such as A-type or B-type that shows the effect of improving the electrical characteristics in the photoconductor subjected to dry grinding until the average particle size becomes 10 μm or less. It became clear that it was limited to.

<Evaluation of crystal stability against solvent>
The oxytitanium phthalocyanine composition has different crystal stability in a solvent depending on its crystal form, production method, environment and the like. The crystal stability of the oxytitanium phthalocyanine composition was tested using the 1,2-dimethoxyethane solvent used during wet dispersion. As a test method, 0.3 g of oxytitanium phthalocyanine composition and 5.7 g of 1,2-dimethoxyethane were dispersed for 2 hours in an ice-cooled ultrasonic cleaner (US-1R output 55 W, oscillation frequency 40 kHz, manufactured by ASONE). It was left for a certain period of time in an environment of about 25 ° C. with light shielding and sealing. After standing, the oxytitanium phthalocyanine composition was collected by filtration and dried, and the powder X-ray diffraction spectrum was measured. The results are shown in Table-5. The case where the original crystal form was maintained was indicated by ◯, the case where a part of other crystal forms was mixed, Δ, and the case where the crystal form transition was caused completely was indicated by ×.

From the results of Table 5 above, D-type oxytitanium phthalocyanine has different transition time depending on the production method, but A-type transition proceeds with time, whereas A-type and B-type crystals are stable without causing crystal transition. Met.
The results of the sensitivity and dark decay of the photoreceptors 8B, 9B, 10B, and 11B using the D-type oxytitanium phthalocyanine composition described in Table 4 are the results of producing and evaluating the photoreceptor immediately after the production of the coating solution. When time passes, the A type transition proceeds and the sensitivity may be lowered. Depending on the production method, storage status, liquid state, etc. of the oxytitanium phthalocyanine composition, the A-type transition time varies from one week, one month, and half a year. May need to be addressed. On the other hand, when the A-type and B-type oxytitanium phthalocyanine compositions are used, there is no crystal type transition, so the sensitivity does not decrease and the coating solution and the photoreceptor can maintain stable performance, which is advantageous in terms of manufacturing. It can be said that there is.

  As described above, a coating solution for forming a photosensitive layer excellent in sensitivity and dark decay is obtained by dry-grinding a specific crystal type oxytitanium phthalocyanine composition such as A-type or B-type to a mean particle size of 10 μm or less, followed by wet dispersion. Can be easily and stably produced.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
5 Transfer device 6 Cleaning device (cleaning part)
7 Fixing Device 41 Developing Tank 42 Agitator 43 Supply Roller 44 Developing Roller 45 Regulating Member 71 Upper Fixing Member (Pressure Roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (6)

  A method for producing a coating solution for forming a photosensitive layer of an electrophotographic photosensitive member having a photosensitive layer containing a phthalocyanine composition on a conductive support, wherein the phthalocyanine composition is a powder X-ray diffraction spectrum by CuKα characteristics, An oxytitanium phthalocyanine composition exhibiting main diffraction peaks at a Bragg angle (2θ ± 0.2 °) of 9.3 °, 10.5 °, 13.2 °, 15.1 °, and 26.2 °, or a Bragg angle ( 2θ ± 0.2 °) an oxytitanium phthalocyanine composition showing main diffraction peaks at 7.6 °, 10.3 °, 22.5 °, 24.2 °, 25.4 ° and 28.6 °, A method for producing a coating solution for forming a photosensitive layer, characterized by performing a dry grinding process and then performing wet dispersion until the average particle size of the phthalocyanine composition is 10 μm or less.   2. The method for producing a coating solution for forming a photosensitive layer according to claim 1, wherein as the dry grinding treatment, a dispersion medium is added to the phthalocyanine composition and a treatment is performed using a paint shaker.   3. The method for producing a coating solution for forming a photosensitive layer according to claim 1, wherein after the dry grinding process, a solvent is added and wet dispersed without separating the phthalocyanine composition and the dispersion medium. Method.   An electrophotographic photosensitive member having a photosensitive layer containing a phthalocyanine composition on a conductive support, wherein the phthalocyanine composition has a Bragg angle (2θ ± 0.2 °) in a powder X-ray diffraction spectrum by CuKα characteristics. An oxytitanium phthalocyanine composition showing main diffraction peaks at 9.3 °, 10.5 °, 13.2 °, 15.1 ° and 26.2 °, or Bragg angle (2θ ± 0.2 °) 7.6 An oxytitanium phthalocyanine composition showing main diffraction peaks at °, 10.3 °, 22.5 °, 24.2 °, 25.4 ° and 28.6 °, and the average particle size of the phthalocyanine composition is 10 μm An electrophotographic photosensitive member characterized by being dry-dispersed and then wet-dispersed until the following.   An electrophotographic photosensitive member; a charging unit that charges the photosensitive member; an image exposing unit that performs image exposure on the charged photosensitive member to form an electrostatic latent image; and development that develops the electrostatic latent image with toner An image forming apparatus comprising: an electrophotographic photosensitive member according to claim 4, wherein the photosensitive member is an electrophotographic photosensitive member according to claim 4.   An electrophotographic photosensitive member; a charging unit that charges the photosensitive member; an image exposing unit that performs image exposure on the charged photosensitive member to form an electrostatic latent image; and development that develops the electrostatic latent image with toner The electrophotographic photosensitive member according to claim 4, wherein the electrophotographic photosensitive member comprises at least one of a transfer unit for transferring toner to a transfer target member. Photo cartridge.

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