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EP-4741933-A1 - ELECTROPHOTOGRAPHIC PHOTORECEPTOR, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS

EP4741933A1EP 4741933 A1EP4741933 A1EP 4741933A1EP-4741933-A1

Abstract

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer disposed on the conductive substrate, and a lamination-type photosensitive layer disposed on the undercoat layer and having a charge generation layer and a charge transport layer, in which the charge transport layer contains a charge transport material and a polyarylate resin, the polyarylate resin contains a dicarboxylic acid unit represented by Formula (A) and a diol unit represented by Formula (B), and an electrostatic capacity of the undercoat layer is 1.0 × 10 -10 F or more and 3.0 × 10 -9 F or less, in Formula (A), Ar A1 and Ar A2 are each independently an aromatic ring which may have a substituent, L A is a single bond or a divalent linking group, and n A1 is 0, 1, or 2, in Formula (B), Ar B1 and Ar B2 are each independently an aromatic ring which may have a substituent, L B is a single bond, an oxygen atom, a sulfur atom, or -C(Rb 1 )(Rb 2 )-, and n B1 is 0, 1, or 2, where Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, and Rb 1 and Rb 2 may be bonded to each other to form a cyclic alkyl group.

Inventors

  • OYAMADA, YUKI
  • SASAKI, TOMOYA
  • KIGOSHI, YOICHI
  • KANO, FUYUKI
  • IWASAKI, MASAHIRO
  • KUSANO, KEISUKE
  • FUJII, RYOSUKE
  • OKAZAKI, YUTO
  • TAKAOKA, KOHEI
  • IDE, KENTA

Assignees

  • FUJIFILM Business Innovation Corp.

Dates

Publication Date
20260513
Application Date
20250429

Claims (10)

  1. An electrophotographic photoreceptor comprising: a conductive substrate; an undercoat layer disposed on the conductive substrate; and a lamination-type photosensitive layer disposed on the undercoat layer and having a charge generation layer and a charge transport layer, wherein the charge transport layer contains a charge transport material and a polyarylate resin, the polyarylate resin contains a dicarboxylic acid unit represented by Formula (A) and a diol unit represented by Formula (B), and an electrostatic capacity of the undercoat layer is 1.0 × 10 -10 F or more and 3.0 × 10 -9 F or less, in Formula (A), Ar A1 and Ar A2 are each independently an aromatic ring which may have a substituent, L A is a single bond or a divalent linking group, and n A1 is 0, 1, or 2, in Formula (B), Ar B1 and Ar B2 are each independently an aromatic ring which may have a substituent, L B is a single bond, an oxygen atom, a sulfur atom, or -C(Rb 1 )(Rb 2 )-, and n B1 is 0, 1, or 2, where Rb 1 and Rb 2 are each independently a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, and Rb 1 and Rb 2 may be bonded to each other to form a cyclic alkyl group.
  2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer has a relative permittivity of 3.0 or more and 5.0 or less.
  3. The electrophotographic photoreceptor according to claim 1 or 2, wherein a ratio of a relative permittivity of the charge transport layer to a relative permittivity of the undercoat layer (a relative permittivity of the charge transport layer/a relative permittivity of the undercoat layer) is 0.010 or more and 0.400 or less.
  4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the undercoat layer contains zinc oxide particles to which an electron-accepting compound is applied, in an amount of 62% by mass or more and 75% by mass or less with respect to the undercoat layer.
  5. The electrophotographic photoreceptor according to claim 4, wherein the electron-accepting compound is an anthraquinone derivative having three OH groups or having two OH groups and one alkoxy group.
  6. The electrophotographic photoreceptor according to claim 5, wherein the anthraquinone derivative is an alizarin derivative represented by Formula (C), in Formula (C), R represents a hydroxyl group or an alkoxy group having 1 or more and 10 or less of carbon atoms.
  7. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein a film thickness of the undercoat layer is 17 µm or more and 35 µm or less.
  8. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the charge transport layer further contains a polycarbonate resin, and the polyarylate resin and a polycarbonate resin each have a constitutional unit including biphenyl represented by Formula (BP), in Formula (BP), j is an integer of 0 or greater and 4 or less, j pieces of R 1 's are each independently a methyl group or an ethyl group, k is an integer of 0 or greater and 4 or less, and k pieces of R 2 's are each independently a methyl group or an ethyl group.
  9. A process cartridge comprising: the electrophotographic photoreceptor according to any one of claims 1 to 8, wherein the process cartridge is attachable to and detachable from an image forming apparatus.
  10. An image forming apparatus comprising: the electrophotographic photoreceptor according to any one of claims 1 to 8; a charging unit that charges a surface of the electrophotographic photoreceptor; an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and a transfer unit that transfers the toner image to a surface of a recording medium.

Description

BACKGROUND OF THE INVENTION (i) Field of the Invention The present disclosure relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. (ii) Description of Related Art JP2013-242483A discloses an electrophotographic photoreceptor including a support, an undercoat layer provided on the support, the undercoat layer containing at least a binder resin, metal oxide particles, and an electron-accepting compound having an anthraquinone structure, in which a content of the electron-accepting compound is 0.5% by mass or more and 1.5% by mass or less with respect to the metal oxide particles, and a contact angle of the metal oxide particles with water is 7 degrees or more and 12 degrees or less, and a photosensitive layer provided on the undercoat layer. JP6838324B discloses an electrophotographic photoreceptor including a conductive substrate, an undercoat layer provided on the conductive substrate, the undercoat layer containing a binder resin, metal oxide particles, and an electron-accepting compound having an anthraquinone skeleton represented by General Formula (1A), in which a reflectivity RL of the undercoat layer to light in a wavelength range of 470 nm or more and 510 nm or less is 2% or more and 5% or less, and a photosensitive layer provided on the undercoat layer. JP2024-043372A discloses an electrophotographic photoreceptor including a conductive substrate, an undercoat layer provided on the conductive substrate, a charge generation layer provided on the undercoat layer, a charge transport layer provided on the charge generation layer, and a protective layer provided on the charge transport layer, in which the undercoat layer contains a conductive agent, the number of primary particles of the conductive agent is 58% or less with respect to the total number of primary particles of the conductive agent and the number of secondary particles of the conductive agent, and the charge mobility µ (CTL) of the charge transport layer and the charge mobility µ (OCL) of the protective layer satisfy µ (CTL) ≥ 1.0 × 10-5 (cm2/Vs) and µ (OCL) ≥ 0.68 × 10-5 (cm2/Vs). SUMMARY OF THE INVENTION An object of the present disclosure is to provide an electrophotographic photoreceptor including a conductive substrate, an undercoat layer disposed on the conductive substrate, and a lamination-type photosensitive layer disposed on the undercoat layer and having a charge generation layer and a charge transport layer, in which the charge transport layer contains a charge transport material and a polyarylate resin having a dicarboxylic acid unit represented by Formula (A) and a diol unit represented by Formula (B), and a potential variation after formation of an electrostatic latent image is suppressed as compared with a case where an electrostatic capacity of the undercoat layer is less than 1.0 × 10-10 F or more than 3.0 × 10-9 F. Specific methods for achieving the above-described object include the following aspects. <1> According to a first aspect of the present disclosure, there is provided an electrophotographic photoreceptor including a conductive substrate, an undercoat layer disposed on the conductive substrate, and a lamination-type photosensitive layer disposed on the undercoat layer and having a charge generation layer and a charge transport layer, in which the charge transport layer contains a charge transport material and a polyarylate resin, the polyarylate resin contains a dicarboxylic acid unit represented by Formula (A) and a diol unit represented by Formula (B), and an electrostatic capacity of the undercoat layer is 1.0 × 10-10 F or more and 3.0 × 10-9 F or less, in Formula (A), ArA1 and ArA2 are each independently an aromatic ring which may have a substituent, LA is a single bond or a divalent linking group, and nA1 is 0, 1, or 2,in Formula (B), ArB1 and ArB2 are each independently an aromatic ring which may have a substituent, LB is a single bond, an oxygen atom, a sulfur atom, or -C(Rb1)(Rb2)-, and nB1 is 0, 1, or 2, where Rb1 and Rb2 are each independently a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, and Rb1 and Rb2 may be bonded to each other to form a cyclic alkyl group.<2> According to a second aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <1>, in which the charge transport layer may have a relative permittivity of 3.0 or more and 5.0 or less.<3> According to a third aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <1> or <2>, in which a ratio of a relative permittivity of the charge transport layer to a relative permittivity of the undercoat layer (a relative permittivity of the charge transport layer/a relative permittivity of the undercoat layer) may be 0.010 or more and 0.400 or less.<4> Accord