JP6436058B2 - Electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. The electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example, a charge generator, a charge transport agent (for example, a hole transport agent), and a resin (binder resin) for binding them. As the electrophotographic photosensitive member, for example, a multilayer electrophotographic photosensitive member or a single layer type electrophotographic photosensitive member is used. The multilayer electrophotographic photoreceptor includes, as a photosensitive layer, a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The single layer type electrophotographic photosensitive member includes a single layer type photosensitive layer having functions of charge generation and charge transport as a photosensitive layer.

  For example, in the electrophotographic photoreceptor described in Patent Document 1, a photosensitive layer containing at least a charge generator, a charge transport agent, a surfactant, and a binder resin is provided on a conductive substrate. The hydrophobic part of the surfactant has a structure derived from a fluoropropene derivative.

JP 2010-230912 A

  However, with the electrophotographic photosensitive member described in Patent Document 1, it has been difficult to suppress the occurrence of image defects caused by the adhesion of paper dust. In addition, the electrophotographic photoreceptor described in Patent Document 1 has insufficient electrical characteristics.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrophotographic photosensitive member capable of simultaneously suppressing the occurrence of image defects caused by adhesion of paper dust and improving electrical characteristics. That is. Another object of the present invention is to provide a process cartridge and an image forming apparatus that suppress the occurrence of image defects caused by the adhesion of paper dust.

  The electrophotographic photoreceptor of the present invention includes a photosensitive layer. The photosensitive layer contains a surfactant and a binder resin. The content of the surfactant is 0.10 parts by mass or more and 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin. The hydrophobic group of the surfactant is a perfluoroalkyl group. The surfactant has nonionic properties.

  The process cartridge of the present invention includes the above-described electrophotographic photosensitive member.

  An image forming apparatus of the present invention includes the above-described electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the electrophotographic photosensitive member. The exposure unit exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the electrophotographic photosensitive member to a recording medium. When the transfer unit transfers the toner image from the electrophotographic photosensitive member to the recording medium, the electrophotographic photosensitive member is in contact with the recording medium.

  According to the present invention, it is possible to provide an electrophotographic photosensitive member capable of coexisting suppression of occurrence of image defects caused by adhesion of paper dust and improvement of electrical characteristics. In addition, according to the present invention, it is possible to provide a process cartridge and an image forming apparatus that can suppress the occurrence of image defects caused by the adhesion of paper dust.

(A) And (b) is a schematic sectional drawing which respectively shows an example of the electrophotographic photoreceptor which concerns on 1st embodiment of this invention. (A) And (b) is a schematic sectional drawing which shows another example of the electrophotographic photoreceptor which concerns on 1st embodiment of this invention, respectively. It is the schematic which shows an example of a structure of the image forming apparatus which concerns on 2nd embodiment of this invention. (A) And (b) is a microscope picture figure for demonstrating the measuring method of the calcium carbonate residual rate of the photosensitive layer of the electrophotographic photoreceptor which concerns on 1st embodiment of this invention, respectively. (A) And (b) is a microscope picture figure for demonstrating the measuring method of the calcium carbonate residual rate of the photosensitive layer of the electrophotographic photoreceptor which concerns on 1st embodiment of this invention, respectively.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

  Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

  Hereinafter, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an aryl group having 6 to 14 carbon atoms will be described.

  The halogen atom is, for example, fluorine (fluoro group), chlorine (chloro group) or bromine (bromo group).

  The alkyl group having 1 to 6 carbon atoms is a linear or branched alkyl group having 1 to 6 carbon atoms that is unsubstituted. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, and neopentyl group. Or a hexyl group is mentioned.

  The alkoxy group having 1 to 6 carbon atoms is a linear or branched alkoxy group having 1 to 6 carbon atoms which is unsubstituted. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, pentyloxy, iso A pentyloxy group, a neopentyloxy group or a hexyloxy group can be mentioned.

  Examples of the aryl group having 6 to 14 carbon atoms include an unsubstituted aromatic monocyclic hydrocarbon group having 6 to 14 carbon atoms and an unsubstituted aromatic condensed bicyclic carbon group having 6 to 14 carbon atoms. A hydrogen group or an unsubstituted aromatic condensed tricyclic hydrocarbon group having 6 to 14 elemental atoms. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

<First embodiment: electrophotographic photoreceptor>
The first embodiment relates to an electrophotographic photoreceptor (hereinafter sometimes referred to as a photoreceptor). The photoreceptor according to the present embodiment may be a single-layer photoreceptor or a laminated photoreceptor.

  According to the photoconductor of this embodiment, it is possible to achieve both the suppression of the occurrence of image defects caused by the adhesion of paper dust and the improvement of electrical characteristics. The reason is presumed as follows.

  First, the photosensitive layer of the photoreceptor of this embodiment contains a nonionic surfactant whose hydrophobic group is a perfluoroalkyl group. For example, when an image is formed on paper while the photoconductor is in contact with paper as a recording medium, paper dust derived from the paper may adhere to the surface of the photoconductor. When paper dust adheres to the surface of the photoreceptor, an image defect such as a black spot occurs in the formed image. However, since the photosensitive layer of the photoconductor of the present embodiment contains a nonionic surfactant having a perfluoroalkyl group, it acts between molecules on the surface of the photosensitive layer and molecules in the paper powder. It is thought that Van der Waals force (attraction) can be reduced. This makes it difficult for paper dust to adhere to the surface of the photosensitive layer. As a result, it is possible to suppress the occurrence of image defects caused by paper dust adhesion.

  Secondly, the photosensitive layer of the photoreceptor of this embodiment contains a nonionic surfactant whose hydrophobic group is a perfluoroalkyl group as described above. For example, when the photoconductor is in contact with paper as a recording medium in image formation, the paper powder component present in the paper may be negatively charged due to contact with the photoconductor. However, the photoreceptor of this embodiment contains a surfactant having a perfluoroalkyl group. The fluorine atom in the perfluoroalkyl group has a high electronegativity. Therefore, when the photoconductor of this embodiment and paper dust contact, paper dust tends to be positive. As a result, the surface of the photosensitive member charged to, for example, positive polarity in the charging step of the electrophotographic process and paper powder having positive polarity are repelled. This makes it difficult for paper dust to adhere to the surface of the photosensitive layer. As a result, it is possible to suppress the occurrence of image defects caused by paper dust adhesion.

  Third, in the photosensitive layer of the photoreceptor of this embodiment, the surfactant content is 0.10 parts by mass or more and 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin. When the content of the surfactant is 0.10 parts by mass or more with respect to 100.00 parts by mass of the binder resin, the effect of suppressing the occurrence of image defects due to the surfactant described above can be easily obtained. Further, when the surfactant content is 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin, the absolute value of the sensitivity potential of the photoconductor can be reduced, and the electric charge of the photoconductor can be reduced. Characteristics can be improved.

<1. Single-layer type photoreceptor>
Hereinafter, the case where the photoreceptor 1 is a single-layer photoreceptor will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a single-layer type photoreceptor that is an example of the photoreceptor 1 according to the present embodiment.

  As shown in FIG. 1A, the single layer type photoreceptor as the photoreceptor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. When the photoreceptor 1 is a single layer type photoreceptor, the photosensitive layer 3 is a single layer type photosensitive layer 3c. As shown in FIG. 1A, a single-layer type photosensitive layer 3 c may be directly provided on the conductive substrate 2.

  Further, as shown in FIG. 1B, the single layer type photoreceptor as the photoreceptor 1 includes a conductive substrate 2, a single layer type photosensitive layer 3c, and an intermediate layer (undercoat layer) 4. May be. The intermediate layer 4 is provided, for example, between the conductive substrate 2 and the single-layer type photosensitive layer 3c. A protective layer (not shown) may be provided on the single-layer type photosensitive layer 3c.

  The thickness of the single-layer type photosensitive layer 3c is not particularly limited as long as the function as a single-layer type photosensitive layer can be sufficiently expressed. The thickness of the single-layer type photosensitive layer 3c is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

  When the photosensitive layer 3 is a single-layer type photosensitive layer 3c, the single-layer type photosensitive layer 3c as the photosensitive layer 3 contains a surfactant and a binder resin. The single-layer type photosensitive layer 3c may further contain a charge generator, a hole transport agent, and an electron transport agent in addition to the surfactant and the binder resin. The single-layer type photosensitive layer 3c may further contain various additives as necessary. The surfactant, binder resin, charge generator, hole transport agent, electron transport agent and various additives will be described later.

<2. Multilayer photoreceptor>
Hereinafter, with reference to FIG. 2, the case where the photoreceptor 1 is a laminated photoreceptor will be described. FIG. 2 is a schematic cross-sectional view showing a stacked type photoreceptor that is another example of the photoreceptor 1 according to the present embodiment.

  As shown in FIG. 2A, the stacked photoreceptor as the photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The multilayer photoreceptor as the photoreceptor 1 includes a charge generation layer 3 a and a charge transport layer 3 b as the photosensitive layer 3.

  As shown in FIG. 2A, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, an intermediate layer (undercoat layer) 4 may be provided between the conductive substrate 2 and the photosensitive layer 3 as shown in FIG. A protective layer (not shown) may be provided on the photosensitive layer 3.

  The thicknesses of the charge generation layer 3a and the charge transport layer 3b are not particularly limited as long as the functions as the respective layers can be sufficiently expressed. The thickness of the charge generation layer 3a is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less. The thickness of the charge transport layer 3b is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

  When the charge generation layer 3a and the charge transport layer 3b are provided as the photosensitive layer 3, the charge transport layer 3b contains a surfactant and a binder resin. The charge transport layer 3b may contain a hole transport agent. The charge transport layer 3b may further contain an electron acceptor compound and various additives as necessary. The surfactant, binder resin, hole transport agent, electron acceptor compound and various additives will be described later.

  The charge generation layer 3a in the photosensitive layer 3 contains, for example, a charge generation agent. The charge generation layer 3a may contain a binder resin for the charge generation layer 3a (hereinafter sometimes referred to as “base resin”). The charge generation layer 3a may contain various additives as necessary. The charge generator, base resin, and various additives will be described later.

  In order to suppress the occurrence of image defects caused by the adhesion of paper dust, the photosensitive layer 3 containing a surfactant (for example, the single-layer type photosensitive layer 3 c or the charge transport layer 3 b) is the outermost layer of the photoreceptor 1. It is preferable to arrange as a surface layer.

  The structure of the single layer type photoreceptor and the multilayer type photoreceptor, which are photoreceptors, has been described above with reference to FIGS. 1 and 2. Next, elements common to the single layer type photoreceptor and the multilayer type photoreceptor, which are photoreceptors, will be described.

<3. Conductive substrate>
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. The conductive substrate may be formed of a material having at least a surface portion having conductivity. An example of the conductive substrate is a conductive substrate formed of a conductive material. Another example of the conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer from the photosensitive layer to the conductive substrate is good.

  The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus described later in the second embodiment. Examples of the shape of the conductive substrate include a plate shape, a sheet shape, and a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<4. Photosensitive layer>
The photoreceptor of this embodiment includes a photosensitive layer. The calcium carbonate residual ratio R represented by the following mathematical formula (1) of the photosensitive layer is preferably 30% or less. Calcium carbonate is the main component of paper powder. By adjusting the calcium carbonate residual ratio R of the photosensitive layer to 30% or less, it is possible to suppress the occurrence of image defects caused by the adhesion of paper dust.
R = 100 × A2 / A1 (1)

In formula (1), A1 represents the first ratio. The first ratio is the ratio of the surface area of the photosensitive layer to which calcium carbonate is adhered to the total surface area of the photosensitive layer. The first ratio is measured after depositing calcium carbonate in an amount of 0.75 mg per cm ² of the surface of the photosensitive layer on the surface of the photosensitive layer. In formula (1), A2 represents the second ratio. The second ratio is the ratio of the area of the surface of the photosensitive layer where calcium carbonate remains to the total area of the surface of the photosensitive layer. The second ratio is measured after applying a centrifugal force of 12000 G for 3 minutes using a centrifuge to the photosensitive layer to which calcium carbonate is adhered. The calcium carbonate residual rate R of the photosensitive layer is measured by, for example, the method described in Examples. The single-layer type photosensitive layer in the method described in the examples corresponds to the photosensitive layer.

  In order to suppress the occurrence of image defects caused by paper dust adhesion, the calcium carbonate residual ratio R of the photosensitive layer is more preferably greater than 0% and not greater than 30%, and more preferably not less than 10% and not greater than 20%. More preferably, it is 10% or more and 17% or less. When the photoreceptor is a single layer type photoreceptor, the calcium carbonate residual ratio R of the single layer type photosensitive layer is preferably within such a range. When the photoreceptor is a laminated photoreceptor, it is preferable that the calcium carbonate residual ratio R of the charge transport layer is within such a range.

  Further, the residual ratio R of calcium carbonate on the outermost surface layer of the photoreceptor is preferably 30% or less, more preferably greater than 0% and 30% or less, and further preferably 10% or more and 20% or less. It is particularly preferably 10% or more and 17% or less. This is because the residual ratio R of calcium carbonate in the outermost surface layer that is in direct contact with paper dust during image formation tends to affect the suppression of image defects caused by the adhesion of paper dust.

  Next, components contained in the photosensitive layer will be described.

<4-1. Charge generator>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains, for example, a charge generating agent. When the photoreceptor is a multilayer photoreceptor, the charge generation layer contains, for example, a charge generation agent.

  The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, indigo pigments, azulenium pigments, cyanine pigments, inorganic photoconductive materials (for example, selenium , Selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon) powder, pyrylium salt, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment or quinacridone pigment. .

  Examples of the phthalocyanine pigment include metal-free phthalocyanine or metal phthalocyanine represented by the chemical formula (C-1). Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine or chlorogallium phthalocyanine represented by the chemical formula (C-2). The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α type, β type, Y type, V type or II type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

  Examples of the crystal of metal-free phthalocyanine include an X-type crystal of metal-free phthalocyanine (hereinafter sometimes referred to as “X-type metal-free phthalocyanine”). Examples of the crystal of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter sometimes referred to as “α-type, β-type, or Y-type titanyl phthalocyanine”). Examples of the crystal of hydroxygallium phthalocyanine include a V-type crystal of hydroxygallium phthalocyanine. Examples of chlorogallium phthalocyanine crystals include chlorogallium phthalocyanine type II crystals. X-type metal-free phthalocyanine or Y-type titanyl phthalocyanine is preferable and X-type metal-free phthalocyanine is more preferable because it has a high quantum yield in the wavelength region of 700 nm or more.

  A charge generator having an absorption wavelength in a desired region may be used alone, or two or more charge generators may be used in combination. Furthermore, for example, in a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoreceptor having sensitivity in a wavelength region of 700 nm or more. Therefore, for example, phthalocyanine pigments are preferred, metal-free phthalocyanines or titanyl phthalocyanines are more preferred, and X-type metal-free phthalocyanines are particularly preferred. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  An ansanthrone pigment is preferably used as a charge generating agent in a photoreceptor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of about 350 nm to 550 nm).

  When the photoreceptor is a multilayer photoreceptor, the content of the charge generating agent is preferably 5 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the base resin contained in the charge generation layer. More preferably, it is at least 500 parts by mass.

  When the photoreceptor is a single layer type photoreceptor, the content of the charge generating agent is 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. It is preferably 0.5 parts by mass or more and 30 parts by mass or less.

<4-2. Surfactant>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains a surfactant. When the photoreceptor is a multilayer photoreceptor, the charge transport layer contains a surfactant. The hydrophobic group of the surfactant contained in the toner of the present embodiment is a perfluoroalkyl group. The surfactant contained in the toner of this embodiment has nonionic properties. In the surfactant, the hydrophobic group and the hydrophilic group are bonded directly or indirectly.

  The hydrophobic group of the surfactant contained in the toner of the exemplary embodiment is preferably a linear perfluoroalkyl group. In order to suppress the occurrence of image defects caused by adhesion of paper dust and improve electrical characteristics, the hydrophobic group of the surfactant is more preferably a perfluoroalkyl group represented by the following general formula (I). preferable.

  In general formula (I), n represents an integer of 1-20. n preferably represents an integer of 5 to 15.

  The hydrophobic group of the surfactant is particularly preferably a linear perfluoroundecyl group. When the hydrophobic group is a linear perfluoroundecyl group, n in the general formula (I) represents 10. When the surfactant has a linear perfluoroundecyl group, it becomes easy to adjust the calcium carbonate residual ratio R of the photosensitive layer to a desired value. As a result, it is possible to particularly suppress the occurrence of image defects caused by the adhesion of paper dust.

  The entire molecular structure of the surfactant is not particularly limited as long as the hydrophobic group is a perfluoroalkyl group and is nonionic. As the molecular structure of the surfactant, for example, an oligomer other than an ethylene oxide adduct, a polymer, or an ethylene oxide adduct (for example, an oligomer containing a hydrophilic group or an oligomer containing a hydrophilic group and a UV-reactive group). Is mentioned. The surfactant (molecular structure of the surfactant) is an ethylene oxide adduct or a polymer in order to make it easy to achieve both suppression of image defects caused by adhesion of paper dust and improvement of electrical characteristics. It is preferable.

When the surfactant is an ethylene oxide adduct, the hydrophilic group of the surfactant is represented by the general formula “— (O—CH ₂ —CH ₂ ) _m —OH”. In the general formula, m represents the average number of moles of ethylene oxide added. The average added mole number of ethylene oxide is preferably 5 or more and 50 or less. When the average added mole number of ethylene oxide is 5 or more, it is easy to improve the hydrophilicity of the hydrophilic group of the surfactant. When the average added mole number of ethylene oxide is 50 or less, the hydrophilicity of the hydrophilic group of the surfactant does not become too high.

  When the molecular structure of the surfactant is a polymer, it is preferable that the hydrophilic group and the hydrophobic group of the surfactant are bonded by an ester bond.

  The molecular structure of the whole surfactant may further include sites other than the hydrophobic group and the hydrophilic group described above. Examples of such a site include a hydrocarbon group having 5 to 30 carbon atoms, and more specifically, an alkyl group having 5 to 30 carbon atoms. The hydrocarbon group having 5 to 30 carbon atoms may have hydrophobicity. The surface tension of the ethyl acetate solution of the surfactant having a concentration of 0.5% by mass is preferably 18.0 mN / m or more and 24.0 mN / m.

  The content of the surfactant is 0.10 parts by mass or more and 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin. As already described, when the content of the surfactant is 0.10 parts by mass or more with respect to 100.00 parts by mass of the binder resin, the occurrence of image defects caused by the adhesion of paper dust is suitably suppressed. be able to. When the surfactant content is 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin, the electrical characteristics of the photoreceptor can be improved.

  Since it is easy to adjust the calcium carbonate residual ratio R of the photosensitive layer to a desired value, the content of the surfactant is 0.50 parts by mass or more and 3.00 parts by mass with respect to 100.00 parts by mass of the binder resin. Or less, more preferably 1.00 parts by mass or more and 3.00 parts by mass or less. When the photoreceptor is a single layer type photoreceptor, the content of the surfactant is preferably within the above-described range with respect to 100.00 parts by mass of the binder resin contained in the single layer type photosensitive layer. . When the photoreceptor is a multilayer photoreceptor, the content of the surfactant is preferably within the above-described range with respect to 100.00 parts by mass of the binder resin contained in the charge transport layer.

<4-3. Binder resin>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains a binder resin. When the photoreceptor is a laminated photoreceptor, the charge transport layer contains a binder resin.

  The binder resin is not particularly limited as long as it is a binder resin applicable to the photoreceptor. Examples of the binder resin include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Examples of the thermoplastic resin include styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic acid polymer, polyethylene resin, ethylene-vinyl acetate. Copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polycarbonate resin, polyarylate resin, polysulfone resin, diallyl phthalate resin , Ketone resin, polyvinyl butyral resin, polyether resin or polyester resin. Examples of the thermosetting resin include silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, and other crosslinkable thermosetting resins. Examples of the photocurable resin include epoxy acrylate (epoxy compound acrylic acid adduct) or urethane-acrylate (urethane compound acrylic acid adduct). Binder resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these binder resins, the residual ratio R of calcium carbonate in the photosensitive layer (single-layer type photosensitive layer or charge transport layer) is adjusted to a desired value, and it is easy to suppress the occurrence of image defects caused by the adhesion of paper dust. Therefore, a polycarbonate resin is preferable. Polycarbonate resins also have the advantage of having a good balance of processability, mechanical properties, optical properties and wear resistance. Examples of the polycarbonate resin include bisphenol Z type polycarbonate resin, bisphenol ZC type polycarbonate resin, bisphenol C type polycarbonate resin, bisphenol B type polycarbonate resin and bisphenol A type polycarbonate resin. Specific examples of the bisphenol Z-type polycarbonate resin include resins formed from repeating units represented by the following chemical formula (R-1).

  The viscosity average molecular weight of the binder resin is preferably 20,000 or more, and more preferably 20,000 or more and 52,500 or less. When the viscosity average molecular weight of the binder resin is 20,000 or more, it is easy to improve the abrasion resistance of the photoreceptor. When the binder resin has a viscosity average molecular weight of 52,500 or less, the binder resin is easily dissolved in the solvent during the formation of the photosensitive layer, and the viscosity of the single-layer photosensitive layer coating solution or the charge transport layer coating solution increases. Not too much. As a result, it becomes easy to form a single-layer type photosensitive layer or a charge transport layer.

<4-4. Hole transport agent>
When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer contains, for example, a hole transport agent. When the photoreceptor is a multilayer photoreceptor, the charge transport layer contains, for example, a hole transport agent.

  The hole transport agent is not particularly limited as long as it is a hole transport agent for a photoreceptor. Examples of the hole transport agent include triphenylamine derivatives and diamine derivatives (for example, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N′-tetraphenylnaphthylenediamine derivative, N, N, N ′, N′-tetraphenylphenanthrylenediamine derivative or di (aminophenylethenyl) benzene derivative), oxadiazole series A compound (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), a styryl compound (eg, 9- (4-diethylaminostyryl) anthracene), a carbazole compound (eg, , Polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl- -(P-dimethylaminophenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds or triazole compounds. . A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the hole transport agent, a compound represented by the following general formula (II) is preferable. By using a nonionic surfactant having a perfluoroalkyl group in combination with the compound represented by the general formula (II), the electrical characteristics of the photoreceptor can be further improved.

In general formula (II), R < ₁ > -R < ₆ > represents a hydrogen atom, an alkyl group, or an alkoxy group each independently. One or more of R ₁ , R ₂ and R ₃ are an alkyl group or an alkoxy group. That is, not all of R ₁ , R ₂ and R ₃ are hydrogen atoms. One or more of R ₄ , R ₅ and R ₆ are an alkyl group or an alkoxy group. That is, not all of R ₄ , R ₅ and R ₆ are hydrogen atoms.

In general formula (II), each of R _{1 to} R ₆ preferably independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. More preferably, it represents a group or a methoxy group, and particularly preferably represents a methyl group. One or more of R ₁ , R ₂ and R ₃ are preferably an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and is a methyl group or a methoxy group. More preferred is a methyl group. One or more of R ₄ , R ₅ and R ₆ are preferably an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and is a methyl group or a methoxy group. More preferred is a methyl group.

  Specific examples of the compound represented by the general formula (II) include a compound represented by the chemical formula (H-1) (hereinafter sometimes referred to as the compound (H-1)).

  When the photoreceptor is a multilayer photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. More preferably, it is 20 parts by mass or more and 100 parts by mass or less.

  When the photoreceptor is a single layer type photoreceptor, the content of the hole transport agent contained in the single layer type photosensitive layer is 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin. Is preferably 10 parts by mass or more and 100 parts by mass or less.

<4-5. Electron Transfer Agent and Electron Acceptor Compound>
When the photoreceptor is a multilayer photoreceptor, the charge transport layer may contain an electron acceptor compound as necessary. Thereby, it becomes easy to improve the hole transport ability of the hole transport agent. On the other hand, when the photosensitive member is a single layer type photosensitive member, the single layer type photosensitive layer may contain an electron transport agent, if necessary. Thereby, the single-layer type photosensitive layer can transport electrons, and it becomes easy to impart bipolar (bipolar) characteristics to the single-layer type photosensitive layer.

  Examples of electron transfer agents or electron acceptor compounds include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-. Fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. An electron transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type. An electron acceptor compound may also be used individually by 1 type, and may be used in combination of 2 or more type.

  Specific examples of the electron transfer agent and the electron acceptor compound include compounds represented by the general formula (III).

In general formula (III), R ₇ and R ₈ each independently represent a hydrogen atom, a cyano group, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. It represents an alkoxy group that may have, an alkoxycarbonyl group that may have a substituent, an aryl group that may have a substituent, or a heterocyclic group that may have a substituent. In general formula (III), each R ₉ may independently have a hydrogen atom, a halogen atom (preferably a chloro group), a cyano group, an alkyl group which may have a substituent, or a substituent. An alkenyl group, an alkoxy group that may have a substituent, an alkoxycarbonyl group that may have a substituent, an aryl group that may have a substituent, or a heterocyclic group that may have a substituent .

In the general formula (III), the alkyl group represented by R _{7 to} R ₉ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and a methyl group. 1,1-dimethylpropyl group or tert-butyl group is more preferable, and tert-butyl group is particularly preferable. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms which may further have a substituent, or a cyano group. . The number of substituents is not particularly limited, but is preferably 3 or less. Examples of the substituent further included in the aryl group having 6 to 14 carbon atoms as the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, and an alkoxy having 1 to 6 carbon atoms. Group, nitro group, cyano group, alkanoyl group having 2 to 7 carbon atoms (a group in which an alkyl group having 1 to 6 carbon atoms is bonded to a carbonyl group), benzoyl group, phenoxy group, 2 to 7 carbon atoms Examples thereof include the following alkoxycarbonyl groups (groups in which an alkoxy group having 1 to 6 carbon atoms is bonded to a carbonyl group) or phenoxycarbonyl groups.

In general formula (III), the alkenyl group represented by R _{7 to} R ₉ is, for example, a linear or branched, unsubstituted alkenyl group having 2 to 6 carbon atoms. The alkenyl group having 2 to 6 carbon atoms has, for example, 1 to 3 double bonds. Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group, a propenyl group, a butenyl group, a pentenyl group, a pentadienyl group, a hexenyl group, and a hexadienyl group. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formula (III), the alkoxy group represented by R _{7 to} R ₉ is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 3 carbon atoms, and a methoxy group. Is particularly preferred. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group. As the substituent, a phenyl group is preferable. The number of substituents is not particularly limited, but is preferably 3 or less, more preferably 1.

In general formula (III), the alkoxycarbonyl group represented by R _{7 to} R ₉ is, for example, an alkoxycarbonyl group having 2 to 7 carbon atoms. An alkoxycarbonyl group having 2 to 7 carbon atoms is a group in which a linear or branched, unsubstituted alkoxy group having 1 to 6 carbon atoms is bonded to a carbonyl group. The alkoxycarbonyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 14 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formula (III), the aryl group represented by R _{7 to} R ₉ is preferably an aryl group having 6 to 14 carbon atoms, and more preferably a phenyl group. The aryl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, and an alkanoyl having 2 to 7 carbon atoms. A group (a group in which an alkyl group having 1 to 6 carbon atoms is bonded to a carbonyl group), a benzoyl group, a phenoxy group, an alkoxycarbonyl group having 2 to 7 carbon atoms (a carbonyl group having 1 to 6 carbon atoms) A group to which an alkoxy group is bonded), a phenoxycarbonyl group, an aryl group having 6 to 14 carbon atoms, or a biphenyl group. The number of substituents is not particularly limited, but is preferably 3 or less.

In the general formula (III), the heterocyclic group represented by R _{7 to} R ₉ is, for example, a 5-membered or 6-membered single group containing one or more heteroatoms selected from the group consisting of N, S, and O. A heterocyclic group of a ring; a heterocyclic group in which such monocyclic rings are condensed; or a heterocyclic group in which such a monocyclic ring is condensed with a 5-membered or 6-membered hydrocarbon ring. When the heterocyclic group is a condensed ring, the number of rings contained in the condensed ring is preferably 3 or less. Examples of the substituent that the heterocyclic group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, Alkanoyl group having 2 to 7 carbon atoms (a group in which an alkyl group having 1 to 6 carbon atoms is bonded to a carbonyl group), benzoyl group, phenoxy group, alkoxycarbonyl group having 2 to 7 carbon atoms (carbonyl group) Group having an alkoxy group having 1 to 6 carbon atoms bonded thereto, or a phenoxycarbonyl group. The number of substituents is not particularly limited, but is preferably 3 or less.

  Specific examples of the compound represented by the general formula (III) include a compound represented by the chemical formula (E-1) (hereinafter sometimes referred to as the compound (E-1)).

  When the photoreceptor is a multilayer photoreceptor, the content of the electron acceptor compound is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. More preferably, it is 0.5 parts by mass or more and 10 parts by mass or less.

  When the photoreceptor is a single layer type photoreceptor, the content of the electron transport agent is 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. Preferably, it is 10 to 80 parts by mass.

<4-6. Base resin>
When the photoreceptor is a multilayer photoreceptor, the charge generation layer contains a base resin. The base resin is not particularly limited as long as it is a base resin applicable to the photoreceptor. Examples of the base resin are the same as the examples of the binder resin described above. A base resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  The base resin contained in the charge generation layer is preferably different from the binder resin contained in the charge transport layer. In the production of a multilayer photoreceptor, for example, a charge generation layer is formed on a conductive substrate, and a charge transport layer is formed on the charge generation layer. At that time, a charge transport layer coating solution is applied onto the charge generation layer. Therefore, the charge generation layer is preferably not dissolved in the solvent of the charge transport layer coating solution.

<4-7. Additives>
The photosensitive layer (charge generation layer, charge transport layer or single-layer type photosensitive layer) of the photoreceptor may contain an additive as necessary. Examples of additives include deterioration inhibitors (for example, antioxidants, radical scavengers, singlet quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers. , Waxes, acceptors, donors, plasticizers, sensitizers or leveling agents. Antioxidants include, for example, hindered phenols (eg, di (tert-butyl) p-cresol), hindered amines, paraphenylenediamine, arylalkanes, hydroquinones, spirochromans, spirodanone or derivatives thereof, organic sulfur compounds or An organic phosphorus compound is mentioned.

<5. Intermediate layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used for the intermediate layer. The presence of the intermediate layer is considered to suppress the increase in resistance by smoothing the flow of current generated when the photosensitive member is exposed while maintaining an insulating state capable of suppressing the occurrence of leakage.

  Examples of the inorganic particles include metal (for example, aluminum, iron or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide or zinc oxide) particles or non-metal oxide (for example, silica). Particles. These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

  The resin for the intermediate layer is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may contain various additives. The additive is the same as the additive for the photosensitive layer.

<6. Photoconductor manufacturing method>
When the photoreceptor is a multilayer photoreceptor, the multilayer photoreceptor is manufactured, for example, as follows. First, a charge generation layer coating solution and a charge transport layer coating solution are prepared. A charge generation layer is formed by applying a coating solution for charge generation layer onto a conductive substrate and drying. Subsequently, the charge transport layer coating liquid is applied on the charge generation layer and dried to form the charge transport layer. Thereby, a laminated photoreceptor is manufactured.

  The coating solution for the charge generation layer is prepared by dissolving or dispersing the charge generation agent and components added as necessary (for example, base resin and various additives) in a solvent. The charge transport layer coating solution is prepared by dissolving or dispersing a surfactant, a binder resin, and components added as necessary (for example, a hole transport agent, an electron acceptor compound, and various additives) in a solvent. Is done.

  Next, when the photoconductor is a single layer type photoconductor, the single layer type photoconductor is manufactured, for example, as follows. The single-layer type photoreceptor is manufactured by applying a coating solution for a single-layer type photosensitive layer onto a conductive substrate and drying it. Single-layer photosensitive layer coating solution dissolves surfactant, binder resin and components added as needed (for example, charge generator, hole transport agent, electron transport agent and various additives) in solvent. Or it is manufactured by dispersing.

  The solvent contained in the coating solution (charge generating layer coating solution, charge transport layer coating solution or single layer type photosensitive layer coating solution) is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. . Examples of solvents include alcohols (eg, methanol, ethanol, isopropanol or butanol), aliphatic hydrocarbons (eg, n-hexane, octane or cyclohexane), aromatic hydrocarbons (eg, benzene, toluene or xylene), Halogenated hydrocarbons (eg dichloromethane, dichloroethane, carbon tetrachloride or chlorobenzene), ethers (eg dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether or propylene glycol monomethyl ether), ketones (eg acetone, Methyl ethyl ketone or cyclohexanone), esters (eg ethyl acetate or methyl acetate), dimethylformaldehyde, dimethylform Amide or dimethyl sulfoxide. These solvents are used alone or in combination of two or more. In order to improve the workability during the production of the photoreceptor, it is preferable to use a non-halogen solvent (a solvent other than the halogenated hydrocarbon) as the solvent.

  The coating solution is prepared by mixing each component and dispersing in a solvent. For mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used.

  As a method of applying a coating solution (a coating solution for a charge generation layer, a coating solution for a charge transport layer or a coating solution for a single-layer type photosensitive layer), as long as the coating solution can be uniformly applied on a conductive substrate, There is no particular limitation. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

  The method for drying the coating solution (charge generating layer coating solution, charge transport layer coating solution or single layer type photosensitive layer coating solution) is not particularly limited as long as the solvent in the coating solution can be evaporated. For example, the method of heat-processing (hot-air drying) is mentioned using a high-temperature dryer or a vacuum dryer. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

  In addition, the manufacturing method of a photoreceptor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer as necessary. A known method is appropriately selected in the step of forming the intermediate layer and the step of forming the protective layer.

  The photoreceptor according to this embodiment has been described above. According to the photoconductor of this embodiment, it is possible to achieve both the suppression of the occurrence of image defects caused by the adhesion of paper dust and the improvement of electrical characteristics.

<Second Embodiment: Image Forming Apparatus>
The second embodiment relates to an image forming apparatus. Hereinafter, the image forming apparatus 6 according to the present embodiment will be described with reference to FIG. FIG. 3 is a schematic diagram illustrating an example of the configuration of the image forming apparatus 6.

  The image forming apparatus 6 includes the photoreceptor 1 described in the first embodiment, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit 26. The charging unit 27 charges the surface of the photoreceptor 1. The exposure unit 28 exposes the charged surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. The developing unit 29 develops the electrostatic latent image as a toner image. The transfer unit 26 (for example, the transfer roller 41) transfers the toner image from the photoreceptor 1 to the recording medium (for example, paper) P.

  The image forming apparatus 6 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 6 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. The image forming apparatus 6 may be a tandem color image forming apparatus in order to form toner images of the respective colors using different color toners.

  Hereinafter, the image forming apparatus 6 will be described by taking a tandem color image forming apparatus as an example. The image forming apparatus 6 includes a plurality of photoreceptors 1 arranged in parallel in a predetermined direction and a plurality of developing units 29. Each of the plurality of developing units 29 is disposed to face the photoreceptor 1. The developing unit 29 carries and transports toner, and supplies the toner to the surface of the corresponding photoreceptor 1.

  As shown in FIG. 3, the image forming apparatus 6 further includes a box-shaped device housing 7. In the apparatus housing 7, a paper feeding unit 8, an image forming unit 9, and a fixing unit 10 are provided. The paper feed unit 8 feeds the recording medium P. The image forming unit 9 transfers the toner image based on the image data to the recording medium P while conveying the recording medium P fed from the paper feeding unit 8. The fixing unit 10 fixes the unfixed toner image transferred onto the recording medium P by the image forming unit 9 to the recording medium P. Further, a paper discharge unit 11 is provided on the upper surface of the device housing 7. The paper discharge unit 11 discharges the recording medium P fixed by the fixing unit 10.

  The paper feed unit 8 includes a paper feed cassette 12, a first pickup roller 13, a plurality of paper feed rollers 14, and a registration roller pair 17. The paper feed cassette 12 is provided so as to be detachable from the device housing 7. In the paper feed cassette 12, recording media P of various sizes are stored. The first pickup roller 13 is provided at the upper left position of the paper feed cassette 12. The first pickup roller 13 takes out the recording media P stored in the paper feed cassette 12 one by one. The plurality of paper feed rollers 14 convey the recording medium P taken out by the first pickup roller 13. The registration roller pair 17 temporarily supplies the recording medium P conveyed by the plurality of paper feeding rollers 14 to the image forming unit 9 at a predetermined timing.

  The paper feed unit 8 may further include a manual feed tray (not shown) and a second pickup roller (not shown). The manual feed tray is attached to the left side surface of the device housing 7. The second pickup roller takes out the recording medium P placed on the manual feed tray. The recording medium P taken out by the second pickup roller is conveyed by a plurality of paper feed rollers 14 and is supplied to the image forming unit 9 by a registration roller pair 17 at a predetermined timing.

  The image forming unit 9 includes an image forming unit 19 and a transfer belt 40. The image forming unit 19 includes a black image forming unit 22, a cyan image forming unit 23, a magenta image forming unit 24, and a yellow image forming unit 25. From the upstream side (left side in FIG. 3) to the downstream side in the rotation direction of the transfer belt 40 with respect to the black image forming unit 22, the black image forming unit 22, the cyan image forming unit 23, the magenta image forming unit 24, and the yellow image. A forming unit 25 is provided in order. The photosensitive member 1 is provided at the center position of each of the black image forming unit 22, the cyan image forming unit 23, the magenta image forming unit 24, and the yellow image forming unit 25. The photoreceptor 1 is provided so as to be rotatable in the direction of an arrow (counterclockwise). Around each photoconductor 1, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit 26 are sequentially arranged from the upstream side in the rotation direction of each photoconductor 1 with respect to the charging unit 27. .

  One or both of a cleaning device (not shown) and a static eliminator (not shown) may be provided on the upstream side of the charging unit 27 in the rotation direction of the photoreceptor 1. Each of the cleaning device and the charge eliminator cleans and discharges the peripheral surface of the photoreceptor 1 after the transfer of the toner image to the recording medium P is completed. The peripheral surface of the photoreceptor 1 cleaned and discharged by the cleaning device and the charge eliminator is sent to the charging unit 27 and newly charged. When the image forming apparatus 6 includes a cleaning device and a static eliminator, the charging unit 27, the exposure unit 28, the developing unit 29, the transfer unit 26, and the cleaning device with respect to the charging unit 27 from the upstream side in the rotation direction of each photoreceptor 1. And the static eliminator.

  As already described, the charging unit 27 charges the surface (circumferential surface) of the photoreceptor 1. The charging polarity of the charging unit 27 is not particularly limited. When the photosensitive member 1 is a single layer type photosensitive member having a single layer type photosensitive layer 3c (see FIG. 1) as the photosensitive layer 3 (see FIG. 1), the charging unit 27 is used as a photosensitive member in order to improve sensitivity characteristics. It is preferable to charge the surface of 1 positively. In order to improve the sensitivity characteristics when the photosensitive member 1 is a stacked type photosensitive member including a charge generation layer 3a (see FIG. 2) and a charge transport layer 3b (see FIG. 2) as the photosensitive layer 3 (see FIG. 2). The charging unit 27 preferably charges the surface of the photoreceptor 1 to a negative polarity.

  The charging unit 27 may be a non-contact method or a contact method. The non-contact charging unit 27 applies a voltage without contacting the photosensitive member 1. Examples of the non-contact type charging unit 27 include a corona discharge type charging device, and more specifically, a corotron charger or a scorotron charger. The contact-type charging unit 27 is in contact with the photoreceptor 1 and applies a voltage. Examples of the contact-type charging unit 27 include a contact (proximity) discharge type charger, and more specifically, a charging roller or a charging brush. The charging unit 27 is preferably an example charging roller.

  Examples of the charging roller include a charging roller that rotates following the rotation of the photoconductor 1 while in contact with the photoconductor 1. For example, at least a surface portion of the charging roller is formed of a resin. Specifically, the charging roller includes a core metal that is rotatably supported, a resin layer formed on the core metal, and a voltage application unit that applies a voltage to the core metal. The charging unit 27 including such a charging roller charges the surface of the photoreceptor 1 that is in contact with the resin through the resin layer when the voltage application unit applies a voltage to the cored bar.

  The resin that forms the resin layer of the charging roller is not particularly limited as long as the surface of the photoreceptor 1 can be charged satisfactorily. Specific examples of the resin forming the resin layer include a silicone resin, a urethane resin, and a silicone-modified resin. The resin layer may contain an inorganic filler.

  When the image forming apparatus 6 includes the contact-type charging unit 27, it is considered that discharge of active gas (for example, ozone or nitrogen oxide) generated from the charging unit 27 can be suppressed. As a result, it is considered that the deterioration of the photosensitive layer 3 due to the active gas is suppressed and the design considering the office environment can be achieved.

  The voltage applied by the charging unit 27 is not particularly limited. Examples of the voltage applied by the charging unit 27 include an alternating voltage, a superimposed voltage obtained by superimposing an alternating voltage on a direct current voltage, or a direct current voltage. Especially, it is preferable that the charging unit 27 applies only a DC voltage. The charging unit 27 that applies only the DC voltage has the following advantages compared to the charging unit 27 that applies the AC voltage or the charging unit 27 that applies the superimposed voltage obtained by superimposing the AC voltage on the DC voltage. When the charging unit 27 applies only a DC voltage, since the voltage value applied to the photoconductor 1 is constant, the surface of the photoconductor 1 is easily charged uniformly to a constant potential. Further, when the charging unit 27 applies only a DC voltage, the wear amount of the photosensitive layer 3 tends to decrease. As a result, it is considered that a suitable image can be formed.

  The voltage applied to the photosensitive member 1 by the charging unit 27 is preferably 1000 V or more and 2000 V or less, more preferably 1200 V or more and 1800 V or less, and particularly preferably 1400 V or more and 1600 V or less.

  Examples of the exposure unit 28 include an exposure device, and more specifically, a laser scanning unit. The exposure unit 28 exposes the charged surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. Specifically, the exposure unit 28 irradiates the circumferential surface of the photoreceptor 1 uniformly charged by the charging unit 27 with laser light based on image data input from a host device such as a personal computer. Thereby, an electrostatic latent image based on the image data is formed on the peripheral surface of the photoreceptor 1.

  The developing unit 29 develops the electrostatic latent image as a toner image. Specifically, the developing unit 29 supplies toner to the peripheral surface of the photoreceptor 1 on which the electrostatic latent image is formed, and forms a toner image based on the image data. An example of the developing unit 29 is a developing device.

  The developing unit 29 can develop the electrostatic latent image as a toner image while being in contact with the photoreceptor 1. That is, the image forming apparatus 6 according to the present embodiment can employ a so-called contact development method.

  The developing unit 29 can clean the surface of the photoreceptor 1. That is, the image forming apparatus 6 according to the present embodiment can employ a so-called cleaner-less method. The developing unit 29 can remove components adhering to the surface of the photoreceptor 1 (hereinafter sometimes referred to as adhering components). Examples of the adhering component include a toner component (specifically, toner or an external additive detached from the toner) or a non-toner component (specifically, paper powder derived from the recording medium P). .

  The image forming apparatus 6 that employs one or both of the contact developing method and the cleaner-less method usually removes adhering components due to the difference in peripheral speed between the developing unit 29 (for example, developing roller) and the photoreceptor 1 during development. Therefore, image defects caused by the adhesion of paper dust are likely to occur. However, the image forming apparatus 6 of the present embodiment includes the photoreceptor 1 that can suppress the occurrence of image defects caused by the adhesion of paper dust as described above. For this reason, the image forming apparatus 6 according to the present embodiment can suppress image defects caused by adhesion of paper dust on the photoreceptor 1 even when one or both of the contact developing method and the cleanerless method are employed. .

In order for the developing unit 29 to efficiently clean the surface of the photoreceptor 1, it is preferable that the following condition (a) is satisfied. In order for the developing unit 29 to efficiently clean the surface of the photoreceptor 1, it is preferable to satisfy the following condition (b) in addition to the condition (a).
Condition (a): A contact developing method is employed, and a peripheral speed difference is provided between the photoreceptor 1 and the developing unit 29.
Condition (b): The difference between the absolute value of the surface potential of the photoreceptor 1 and the absolute value of the potential of the developing bias satisfies the following formulas (b-1) and (b-2).
0 (V) <absolute value of developing bias potential (V) <absolute value of surface potential of unexposed area of photoreceptor 1 (V) (b-1)
Absolute value of developing bias potential (V)> Absolute value of surface potential of exposed area of photoreceptor 1 (V)> 0 (V) (b-2)

  When the contact development method shown in the condition (a) is adopted and a peripheral speed difference is provided between the photosensitive member 1 and the developing unit 29, the surface of the photosensitive member 1 comes into contact with the developing unit 29, and the photosensitive member 1 The adhering component on the surface is removed by friction with the developing unit 29.

Rotational speed (peripheral speed) V _P of the photosensitive member 1 is preferably not less than 120 mm / sec 350 mm / sec. The rotational speed (circumferential speed) V _D of the developing unit 29 is preferably 133 mm / second or more and 700 mm / second or less. Further, it is preferable that the ratio between the rotational speed V _P of the photoreceptor 1 and the rotational speed V _D of the developing unit 29 satisfies the formula (a-1). When this ratio V _P / V _D is other than 1, it indicates that a peripheral speed difference is provided between the photosensitive member 1 and the developing unit 29.
0.5 ≦ V _P / V _D ≦ 0.8 (a-1)

  Formula (b-1) of the condition (b) relates to the surface potential of the unexposed area of the photoreceptor 1 that has not been exposed by the exposure unit 28. The expression (b-2) of the condition (b) relates to the surface potential of the exposure area of the photoreceptor 1 exposed by the exposure unit 28. It should be noted that the surface potential of the unexposed area and the exposed area of the photoconductor 1 are the same as the surface potential of the photoconductor 1 after the transfer unit 26 transfers the toner image from the photoconductor 1 to the recording medium P. Measured before charging the surface. Regarding the condition (b), when the photosensitive member 1 is a single layer type photosensitive member, for example, the charging polarity of the toner is positive, and the developing method is a reversal developing method. When the photoreceptor 1 is a single-layer photoreceptor, the potential of the developing bias, the surface potential of the unexposed area of the photoreceptor 1 and the surface potential of the exposed area of the photoreceptor 1 are all set to positive values, for example. Can do. When the photoreceptor 1 is a multilayer photoreceptor, for example, the charging polarity of the toner is negative, and the developing method is a reversal developing method. When the photoreceptor 1 is a multilayer photoreceptor, the potential of the developing bias, the surface potential of the unexposed area of the photoreceptor 1 and the surface potential of the exposed area of the photoreceptor 1 are all negative values, for example. it can.

  If a difference is provided between the absolute value of the potential of the developing bias shown in the condition (b) and the absolute value of the surface potential of the photosensitive member 1, the absolute value of the surface potential (charged potential) of the photosensitive member 1 is obtained in the unexposed area. Since the value and the absolute value of the potential of the developing bias satisfy the mathematical formula (b-1), they act between the residual toner (hereinafter sometimes referred to as residual toner) and the unexposed area of the photoreceptor 1. The electrostatic repulsive force is larger than the electrostatic repulsive force acting between the residual toner and the developing unit 29. Therefore, the residual toner in the unexposed area of the photoreceptor 1 moves from the surface of the photoreceptor 1 to the developing unit 29 and is collected.

  If a difference is provided between the absolute value of the potential of the developing bias shown in the condition (b) and the absolute value of the surface potential of the photoreceptor 1, the absolute value of the surface potential (sensitivity potential) of the photoreceptor 1 in the exposure region. And the absolute value of the potential of the developing bias satisfy the formula (b-2), the electrostatic repulsive force acting between the residual toner and the exposed area of the photoreceptor 1 is between the toner and the developing unit 29. It is smaller than the electrostatic repulsion that acts. For this reason, the residual toner in the exposed area of the photoreceptor 1 is held in the exposed area of the photoreceptor 1. The toner held in the exposure area of the photoreceptor 1 is used as it is for image formation.

  The absolute value of the potential of the developing bias is, for example, 250V or more and 400V or less. The absolute value of the charging potential of the photoreceptor 1 is, for example, not less than 450V and not more than 900V. The absolute value of the sensitivity potential of the photoreceptor 1 is, for example, 50 V or more and 200 V or less. The difference between the absolute value of the potential of the developing bias and the absolute value of the charging potential of the photoconductor 1 is, for example, 100 V or more and 700 V or less. The difference between the absolute value of the potential of the developing bias and the absolute value of the sensitivity potential of the photoreceptor 1 is, for example, 150 V or more and 300 V or less. Here, the potential difference indicates the absolute value of the difference. When the photoconductor 1 is a single-layer photoconductor, conditions for providing such a potential difference include, for example, a developing bias potential of +330 V, a charge potential of the photoconductor 1 of +600 V, and a sensitivity of the photoconductor 1. For example, the potential may be set to + 100V.

  The transfer unit 26 (for example, the transfer roller 41) transfers the toner image formed on the surface of the photoreceptor 1 from the photoreceptor 1 to a recording medium (for example, paper) P. When the toner image is transferred, the photoreceptor 1 is in contact with the recording medium P. That is, the image forming apparatus 6 according to the present embodiment employs a so-called direct transfer method. Usually, in an image forming apparatus that employs a direct transfer method, the photosensitive member 1 and the recording medium P are in contact with each other at the time of transfer, so that paper dust derived from the recording medium P is likely to adhere to the photosensitive member 1. However, the image forming apparatus 6 of the present embodiment includes the photoreceptor 1 that can suppress the occurrence of image defects caused by the adhesion of paper dust. For this reason, the image forming apparatus 6 according to the present embodiment can suppress the occurrence of image defects caused by the adhesion of paper dust on the photoreceptor 1 even when the direct transfer method is adopted.

  The transfer belt 40 is an endless belt-like rotating body. The transfer belt 40 is stretched over the drive roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41. The transfer belt 40 is arranged so that the circumferential surface of each photoconductor 1 abuts on the surface (contact surface) of the transfer belt 40. The transfer belt 40 is pressed against the photoconductor 1 by each transfer roller 41 disposed to face each photoconductor 1. In the pressed state, the transfer belt 40 is rotated endlessly by the plurality of rollers 30, 31, 32 and 41. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the transfer belt 40 endlessly. The driven roller 31, the backup roller 32, and the transfer roller 41 are provided rotatably. As the transfer belt 40 is rotated endlessly by the drive roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41 are driven to rotate. These rollers 31, 32 and 41 are driven to rotate and support the transfer belt 40. The recording medium P supplied from the registration roller pair 17 is sucked onto the transfer belt 40 by the suction roller 42. The recording medium P adsorbed on the transfer belt 40 passes between each photoconductor 1 and the corresponding transfer roller 41 as the transfer belt 40 rotates.

  Specifically, each transfer roller 41 applies a transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the recording medium P adsorbed on the transfer belt 40. Thus, the toner image formed on the photoconductor 1 is transferred to the recording medium P between each photoconductor 1 and the corresponding transfer roller 41. When the toner image is transferred, the photosensitive member 1 is in contact with the recording medium P as described above. The transfer belt 40 circulates in the arrow (clockwise) direction by driving the driving roller 30. Accordingly, the recording medium P adsorbed on the transfer belt 40 sequentially passes between each photoconductor 1 and the corresponding transfer roller 41. When passing, the corresponding color toner images formed on the respective photoconductors 1 are sequentially transferred to the recording medium P in an overcoated state.

  The fixing unit 10 fixes the unfixed toner image transferred to the recording medium P. The fixing unit 10 includes a heating roller 34 and a pressure roller 35. The heating roller 34 is heated by an energized heating element. The pressure roller 35 is disposed to face the heating roller 34, and the circumferential surface of the pressure roller 35 is pressed against the circumferential surface of the heating roller 34.

  The recording medium P on which the toner image is fixed is transported by a plurality of transport rollers 36 and is discharged from the paper discharge unit 11. The paper discharge unit 11 is formed by recessing the top of the device housing 7. A paper discharge tray 37 that receives the discharged recording medium P is provided at the bottom of the recessed portion.

  The image forming apparatus according to this embodiment has been described above with reference to FIG. The image forming apparatus according to the present embodiment includes the photoconductor according to the first embodiment. According to the photoreceptor 1, as described in the first embodiment, it is possible to achieve both suppression of image defects caused by the adhesion of paper dust and improvement of electrical characteristics. Therefore, according to the image forming apparatus according to the present embodiment, it is possible to suppress the occurrence of image defects caused by the adhesion of paper dust. Further, according to the image forming apparatus according to the present embodiment, it is considered that the occurrence of an image defect caused by a decrease in electrical characteristics can be suppressed.

<Third embodiment: Process cartridge>
The third embodiment relates to a process cartridge. Hereinafter, with reference to FIG. 3 again, the process cartridge of the present embodiment will be described. The process cartridge of this embodiment corresponds to the black image forming unit 22, the cyan image forming unit 23, the magenta image forming unit 24, or the yellow image forming unit 25 described in the second embodiment. The process cartridge includes, for example, the photoreceptor 1 according to the first embodiment that is unitized. In the process cartridge, for example, in addition to the photoreceptor 1, at least one selected from the group consisting of the charging unit 27, the exposure unit 28, the developing unit 29, and the transfer unit 26 described in the second embodiment is unitized. The configuration is adopted. The process cartridge may be designed to be detachable from the image forming apparatus 6 according to the second embodiment.

  The process cartridge according to this embodiment has been described above with reference to FIG. The process cartridge according to the present embodiment includes the photoconductor according to the first embodiment. As described in the first embodiment, the photoconductor can achieve both suppression of the occurrence of image defects caused by adhesion of paper dust and improvement of electrical characteristics. Therefore, according to the process cartridge according to the present embodiment, it is possible to suppress the occurrence of image defects caused by the adhesion of paper dust. Further, according to the process cartridge according to the present embodiment, it is considered that the occurrence of an image defect caused by a decrease in electrical characteristics can be suppressed. Further, since such a process cartridge is easy to handle, it can be easily and quickly replaced including the photosensitive member when the sensitivity characteristic of the photosensitive member is deteriorated.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the scope of the examples.

<1. Material of single layer type photoreceptor>
The following surfactants, charge generating agents, hole transporting agents, binder resins and electron transporting agents were prepared as materials for forming the single layer type photosensitive layer of the single layer type photoreceptor.

(Surfactant)
As surfactants, the following surfactants (S651), (S611), (S420), (212P), (215M) and (222F) were prepared.

  The surfactant (S651) was “Surflon S-651” manufactured by AGC Seimi Chemical Co., Ltd. This surfactant was a polymer and was a nonionic fluorine-containing surfactant having a linear perfluoroundecyl group as a hydrophobic group. The surface tension of this surfactant (0.5% by mass) in ethyl acetate was 23.0 mN / m.

  The surfactant (S611) was “Surflon S-611” manufactured by AGC Seimi Chemical Co., Ltd. This surfactant was a polymer and was a nonionic fluorine-containing surfactant having a linear perfluoroundecyl group as a hydrophobic group. The surface tension of this surfactant (0.5% by mass) in ethyl acetate was 18.4 mN / m.

  The surfactant (S420) was “Surflon S-420” manufactured by AGC Seimi Chemical Co., Ltd. This surfactant was a nonionic fluorine-containing surfactant having a linear perfluoroundecyl group as a hydrophobic group. This surfactant was an ethylene oxide adduct. The surface tension of this surfactant (0.5 mass%) in ethyl acetate was 23.1 mN / m.

  The surfactant (212P) was “Fargent 212P” manufactured by Neos Corporation. This surfactant was nonionic and had a group derived from a compound represented by the following chemical formula (A) as a hydrophobic group. The hydrophobic group of this surfactant was a branched fluoroalkenyl group having a double bond. This surfactant was polyoxyethylene ether, and the average added mole number of ethylene oxide was 12.

  The surfactant (215M) was “Factent 215M” manufactured by Neos Co., Ltd. This surfactant was nonionic and had a group derived from a compound represented by the following chemical formula (A) as a hydrophobic group. The hydrophobic group of this surfactant was a branched fluoroalkenyl group having a double bond. This surfactant was polyoxyethylene ether, and the average added mole number of ethylene oxide was 15.

  The surfactant (222F) was “Factent 222F” manufactured by Neos Co., Ltd. This surfactant was nonionic and had a group derived from a compound represented by the following chemical formula (A) as a hydrophobic group. The hydrophobic group of this surfactant was a branched fluoroalkenyl group having a double bond. This surfactant was polyoxyethylene ether, and the average number of moles of ethylene oxide added was 22.

(Charge generator)
Compound (C-1X) was prepared as a charge generating agent. The compound (C-1X) was a metal-free phthalocyanine represented by the chemical formula (C-1) described in the embodiment. In addition, the crystal structure of the compound (C-1X) was X type.

(Hole transport agent)
The compound (H-1) described in the embodiment was prepared as a hole transport agent.

(Binder resin)
Resin (R-1a) was prepared as a binder resin. The resin (R-1a) was a polycarbonate resin (bisphenol Z-type polycarbonate resin) formed from the repeating unit represented by the chemical formula (R-1) described in the embodiment. The viscosity average molecular weight of the resin (R-1a) was 30000.

(Electron transfer agent)
The compound (E-1) described in the embodiment was prepared as an electron transport agent.

<2. Manufacture of single layer type photoreceptor>
Single layer type photoreceptors (P-1) to (P-22) were manufactured using the prepared material for forming the photosensitive layer.

<2-1. Manufacture of single layer type photoreceptor (P-2)>
In the container, 0.10 parts by mass of a surfactant (S651), 3.00 parts by mass of a compound (C-1X) as a charge generating agent, and 70.00 parts of a compound (H-1) as a hole transporting agent. Parts by weight, 30.00 parts by weight of compound (E-1) as an electron transport agent, 100.00 parts by weight of resin (R-1a) as a binder resin, and 250.00 parts by weight of tetrahydrofuran as a solvent. I put it in. The contents of the container were mixed for 12 hours using a ball mill to disperse the material in the solvent. This obtained the coating liquid for single layer type photosensitive layers. The single layer type photosensitive layer coating solution was coated on a conductive substrate (aluminum drum) by using a dip coating method. The applied coating liquid for single-layer type photosensitive layer was dried with hot air at 120 ° C. for 60 minutes. As a result, a single-layer type photosensitive layer (thickness 30 μm) was formed on the conductive substrate. As a result, a single layer type photoreceptor (P-2) was obtained.

<2-2. Production of Single Layer Type Photoreceptors (P-1) and (P-3) to (P-22)>
The single-layer photoconductors (P-1) and (P-3) to (P-22) were prepared in the same manner as in the production of the single-layer photoconductor (P-2) except that the following points were changed. Manufactured. The type and content (addition amount) of the surfactant are changed from 0.10 parts by mass of the surfactant (S651) in the production of the single-layer photoreceptor (P-2), and the types of surfactants shown in Table 1 and The content (added amount) was changed.

<3. Measurement of residual ratio R of calcium carbonate>
For each of the obtained single layer type photoreceptors (P-1) to (P-22), the calcium carbonate residual ratio R of the photosensitive layer (single layer type photosensitive layer) was measured. The single-layer photosensitive layer coating solution used for the production of each single-layer photoreceptor was applied on a conductive substrate (aluminum plate, 40 mm long × 30 mm wide × 2 mm thick) by dip coating. . The applied coating liquid for single-layer type photosensitive layer was dried with hot air at 120 ° C. for 40 minutes. As a result, a single-layer type photosensitive layer (thickness 30 μm) was formed on the conductive substrate.

  Subsequently, the calcium carbonate residual ratio R of the formed single-layer type photosensitive layer was measured. The measurement of the calcium carbonate residual ratio R was performed in an environment of a temperature of 23 ° C. and a humidity of 50% RH (relative humidity).

First, 9.00 mg of calcium carbonate was adhered to the surface of the formed single-layer type photosensitive layer. This corresponded to an amount of calcium carbonate of 0.75 mg per 1 cm ² of the surface of the single-layer type photosensitive layer. Subsequently, the surface of the single-layer type photosensitive layer to which calcium carbonate was adhered was observed at a magnification of 500 times using an optical microscope (Nikon Corporation “Senner KK”) to obtain an observation image. FIG. 4A shows an example of the obtained observation image (observation image of the surface of the single-layer type photosensitive layer before centrifugation described later and before binarization). The pixels constituting the obtained observation image each had a luminance value of 0 or more and 255 or less. Using the image analysis software (Image J), the observed image was subjected to a binarization process using the luminance value 50 as a threshold value. A pixel having a luminance value less than the threshold corresponds to a region to which calcium carbonate is attached. On the other hand, a pixel having a luminance value equal to or higher than the threshold corresponds to a region where calcium carbonate is not attached. An example of the binarized image (observed image of the surface of the single-layer type photosensitive layer before and after centrifugation described later) is shown in FIG. In FIG. 4B, the portion shown in white is a pixel having a luminance value less than the threshold value, and corresponds to a region to which calcium carbonate has adhered.

By binarization, the area (A1c) of the region to which calcium carbonate adhered and the area (A1n) of the region to which calcium carbonate did not adhere were measured. From the obtained A1c and A1n, the ratio (A1) of the surface area of the monolayer type photosensitive layer to which calcium carbonate adhered to the total area of the surface of the monolayer type photosensitive layer is calculated according to the following formula (1-1). did.
A1 (%) = 100 × A1c / (A1c + A1n) (1-1)

  Then, the electroconductive base provided with the single layer type photosensitive layer to which calcium carbonate was adhered was set in a centrifuge (“Micro Cooling Centrifuge 3740” manufactured by Kubota Corporation, constant temperature specification). Then, using the centrifugal separator, the set conductive substrate was rotated for 3 minutes under the condition that a centrifugal force of 12000 G was applied to the single-layer type photosensitive layer. After applying centrifugal force (after rotation), the conductive substrate was taken out from the centrifuge. Microscopic observation and binarization processing were performed on the single-layer type photosensitive layer provided on the extracted conductive substrate by the same method as the measurement of A1c and A1n described above. An example of an observation image of the surface of the single-layer type photosensitive layer after centrifugation and before binarization is shown in FIG. FIG. 5B shows an example of an observation image of the surface of the single-layer type photosensitive layer after the centrifugation and after the binarization process. In FIG. 5 (b), the portion shown in white is a pixel having a luminance value less than the threshold value, and corresponds to a region where calcium carbonate remains.

By binarization treatment, the area (A2c) of the area where calcium carbonate remained after application of centrifugal force and the area (A2n) of the area where calcium carbonate did not remain after application of centrifugal force were measured. From the obtained A2c and A2n, the ratio (A2) of the surface area of the photosensitive layer where calcium carbonate remained to the total surface area of the single-layer type photosensitive layer was calculated according to the following formula (1-2).
A2 (%) = 100 × A2c / (A2c + A2n) (1-2)

From A1 and A2 calculated as described above, the calcium carbonate residual rate R was calculated according to the following mathematical formula (1). Table 1 shows the measured calcium carbonate residual ratio R.
R (%) = 100 × A2 / A1 (1)

<4. Evaluation of image characteristics>
Image characteristics were evaluated for each of the obtained single layer type photoreceptors (P-1) to (P-22). The evaluation of image characteristics was performed in an environment of a temperature of 35 ° C. and a humidity of 85% RH (relative humidity). As an evaluation machine, an image forming apparatus (modified machine of “monochrome printer FS-1300D” manufactured by Kyocera Document Solutions Co., Ltd.) was used. This image forming apparatus employs a contact development method, a direct transfer method, and a cleaner-less method. In this image forming apparatus, a charging roller is provided as a charging unit. As a recording medium, “Kyocera Document Solutions Brand Paper VM-A4” (A4 size) sold by Kyocera Document Solutions Inc. was used. A one-component developer (prototype) was used for evaluation by the evaluation machine.

  Using an evaluation machine, images I (images with a printing rate of 1%) were continuously printed on 20000 sheets of recording media under the condition of a single layer type photoreceptor rotating at 168 mm / sec. Subsequently, the image II (blank paper image, 210 mm long × 297 mm wide, A4 size) was printed on one recording medium. The recording medium on which the image II was formed was observed with the naked eye, and the presence or absence of image defects in the formed image was observed. As the image defect, the number of black spots appearing in the blank image was counted. When paper dust adheres to the photoreceptor, black spots tend to appear in the blank paper image. Table 1 shows the number of black spots appearing in the blank image. The smaller the number of black spots, the more the occurrence of image defects caused by the adhesion of paper dust is suppressed.

<5. Evaluation of electrical characteristics>
The electrical characteristics of each of the obtained single layer type photoreceptors (P-1) to (P-22) were evaluated. The electrical characteristics were evaluated in an environment with a temperature of 23 ° C. and a humidity of 50% RH (relative humidity). First, using a drum sensitivity tester (manufactured by Gentec Co., Ltd.), the surface of the single layer type photoreceptor was charged to positive polarity. The surface potential of the single layer type photoreceptor immediately after charging was measured. The measured surface potential of the single layer type photoreceptor was defined as the initial potential (V ₀ , unit + V). Next, monochromatic light (wavelength 780 nm, half-value width 20 nm, light energy 1.5 μJ / cm ² ) was extracted from the white light of the halogen lamp using a bandpass filter. The surface of the monolayer type photoreceptor was irradiated with the extracted monochromatic light. The surface potential of the single-layer photoreceptor was measured after 0.5 seconds had elapsed from the end of irradiation. The measured surface potential was defined as the sensitivity potential (V _L , unit + V). Table 1 shows the measured initial potential (V ₀ ) and sensitivity potential (V _L ) of the single-layer type photoreceptor. Note that the smaller the absolute value of the sensitivity potential (V _L ), the better the electrical characteristics of the single layer type photoreceptor.

In Table 1, “residual rate R” indicates the calcium carbonate residual rate R of the single-layer type photosensitive layer represented by the formula (1). In Table 1, “V ₀ ” and “V _L ” indicate the initial potential and sensitivity potential of the single-layer type photoreceptor.

The single layer type photosensitive layers (P-2) to (P-5), (P-8) to (P-11), and (P-14) to (P-17) have surface-active properties. Agent and binder resin. The content of the surfactant was 0.10 parts by mass or more and 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin. The hydrophobic group of the surfactant was a perfluoroalkyl group. The surfactant had nonionic properties. Therefore, as is clear from Table 1, in these single layer type photoreceptors, the number of black spots was 5 or less, and the occurrence of image defects caused by the adhesion of paper dust was suppressed. In addition, these single-layer type photoreceptors had a sensitivity potential (V _L ) of +120 V or less, and were excellent in electrical characteristics.

  In the single-layer type photosensitive layers of the single-layer type photoreceptors (P-1), (P-7), and (P-13), the content of the surfactant is 0. 0 with respect to 100.00 parts by mass of the binder resin. The amount was less than 10 parts by mass. Therefore, as is apparent from Table 1, in these single layer type photoreceptors, many image defects (black spots) caused by the adhesion of paper dust occurred and the image characteristics were inferior.

In the single layer type photosensitive layers (P-6), (P-12), and (P-18) of the single layer type photoreceptors, the surfactant content is 3 to 100.00 parts by mass of the binder resin. It was over 00 parts by mass. Therefore, as is apparent from Table 1, these single-layer type photoreceptors have a large absolute value of the sensitivity potential (V _L ) and inferior electrical characteristics.

  The single-layer photosensitive layer of the single-layer photoreceptor (P-19) did not contain a surfactant. Therefore, as is apparent from Table 1, in this single-layer type photoreceptor, many image defects (black spots) caused by the adhesion of paper dust occurred and the image characteristics were inferior.

The hydrophobic group of the surfactant contained in the single-layer type photosensitive layers of the single-layer type photoconductors (P-20) to (P-22) was a fluoroalkenyl group and not a perfluoroalkyl group. Therefore, as is apparent from Table 1, in these single layer type photoreceptors, many image defects (black spots) caused by the adhesion of paper dust occurred and the image characteristics were inferior. Furthermore, in the single layer type photoreceptor (P-22), the absolute value of the sensitivity potential (V _L ) was large and the electrical characteristics were inferior.

  From the above, according to the photoreceptor of the present invention, it has been shown that it is possible to achieve both the suppression of the occurrence of image defects caused by the adhesion of paper dust and the improvement of electrical characteristics.

  The photoconductor according to the present invention can be used in, for example, an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 3 Photosensitive layer 3a Charge generation layer 3b Charge transport layer 3c Single layer type photosensitive layer 6 Image forming apparatus 26 Transfer unit 27 Charging unit 28 Exposure unit 29 Development unit P Recording medium

Claims (8)

Provided with a photosensitive layer containing a surfactant and a binder resin,
The content of the surfactant is 0.50 parts by mass or more and 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin.
The hydrophobic group of the surfactant is a linear perfluoroundecyl group ,
The surfactant, have a nonionic,
The photosensitive layer is a single-layer type photosensitive layer,
The single-layer photosensitive layer is an electrophotographic photosensitive member containing the surfactant, the binder resin, a charge generating agent, a hole transporting agent, and an electron transporting agent . The electrophotographic photosensitive member according to claim 1, wherein a calcium carbonate residual ratio R represented by the following mathematical formula (1) of the photosensitive layer is 30% or less.
R = 100 × A2 / A1 (1)
In the formula (1),
A1 represents a first ratio which is a ratio of the area of the surface of the photosensitive layer to which calcium carbonate has adhered to the total area of the surface of the photosensitive layer, and the first ratio is 0 per 1 cm ² of the surface of the photosensitive layer. Measured after depositing an amount of .75 mg of said calcium carbonate on said surface of said photosensitive layer;
A2 represents a second ratio which is a ratio of the surface area of the photosensitive layer where the calcium carbonate remains to the total area of the surface of the photosensitive layer, and the second ratio allows the calcium carbonate to adhere. Further, the measurement is performed after applying a centrifugal force of 12000 G for 3 minutes to the photosensitive layer using a centrifuge. The binder resin is a polycarbonate resin, electrophotographic photosensitive member according to claim 1 or 2. A process cartridge comprising the electrophotographic photosensitive member according to any one of claims 1 to 3 . An image forming apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 3 , a charging unit, an exposure unit, a developing unit, and a transfer unit,
The charging unit charges the surface of the electrophotographic photosensitive member,
The exposing unit exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image on the surface of the electrophotographic photosensitive member;
The developing unit develops the electrostatic latent image as a toner image,
The transfer unit transfers the toner image from the electrophotographic photosensitive member to a recording medium,
The image forming apparatus, wherein the electrophotographic photosensitive member is in contact with the recording medium when the transfer unit transfers the toner image from the electrophotographic photosensitive member to the recording medium. The image forming apparatus according to claim 5 , wherein the developing unit develops the electrostatic latent image as the toner image while being in contact with the electrophotographic photosensitive member. The developing unit cleans the surface of the electrophotographic photoreceptor, an image forming apparatus according to claim 5 or 6. The charging unit is a charging roller, the image forming apparatus according to any one of claims 5-7.