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EP-4741930-A1 - ELECTROPHOTOGRAPHIC PHOTORECEPTOR, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS

EP4741930A1EP 4741930 A1EP4741930 A1EP 4741930A1EP-4741930-A1

Abstract

An electrophotographic photoreceptor includes a conductive substrate, and a photosensitive layer disposed on the conductive substrate, in which an outermost surface layer contains a first resin, a second resin, a charge transport material, and an antioxidant, at least one of the first resin or the second resin has a constitutional unit including a biphenyl represented by Formula (BPa), at least one of the charge transport material or the antioxidant has at least one of the biphenyl represented by Formula (BPa) or a biphenyl represented by Formula (BPb) in a molecule, and in a case where the number of the biphenyls per unit molecular weight of each of the first resin, the second resin, the charge transport material, and the antioxidant is denoted by BP1, BP2, BP3, and BP4, and in a case where a proportion (% by mass) of each of the first resin, the second resin, the charge transport material, and the antioxidant in a total amount of the first resin, the second resin, the charge transport material, and the antioxidant is denoted by MP1, MP2, MP3, and MP4, a relationship of 0.0 ≤ (BP1 × MP1 + BP2 × MP2)/(BP3 × MP3 + BP4 × MP4) ≤ 3.0 is satisfied, in Formula (BPa), 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, where a plurality of methyl groups and/or ethyl groups may be linked to each other to form a ring, in Formula (BPb), m is an integer of 0 or greater and 4 or less, m pieces of R 3 's are each independently a methyl group or an ethyl group, n is an integer of 0 or more and 5 or less, and n pieces of R 4 's are each independently a methyl group or an ethyl group, where a plurality of methyl groups and/or ethyl groups may be linked to each other to form a ring.

Inventors

  • KUSANO, KEISUKE
  • IDE, KENTA
  • KANO, FUYUKI
  • KIGOSHI, YOICHI
  • OYAMADA, YUKI
  • TAKAOKA, KOHEI

Assignees

  • FUJIFILM Business Innovation Corp.

Dates

Publication Date
20260513
Application Date
20251001

Claims (13)

  1. An electrophotographic photoreceptor comprising: a conductive substrate; and a photosensitive layer disposed on the conductive substrate, wherein an outermost surface layer contains a first resin, a second resin, a charge transport material, and an antioxidant, at least one of the first resin or the second resin has a constitutional unit including a biphenyl represented by Formula (BPa), at least one of the charge transport material or the antioxidant has at least one of the biphenyl represented by Formula (BPa) or a biphenyl represented by Formula (BPb) in a molecule, and in a case where the number of the biphenyls per unit molecular weight of each of the first resin, the second resin, the charge transport material, and the antioxidant is denoted by BP1, BP2, BP3, and BP4, and in a case where a proportion (% by mass) of each of the first resin, the second resin, the charge transport material, and the antioxidant in a total amount of the first resin, the second resin, the charge transport material, and the antioxidant is denoted by MP1, MP2, MP3, and MP4, a relationship of 0.0 ≤ (BP1 × MP1 + BP2 × MP2)/(BP3 × MP3 + BP4 × MP4) ≤ 3.0 is satisfied, in Formula (BPa), 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, where a plurality of methyl groups and/or ethyl groups may be linked to each other to form a ring, in Formula (BPb), m is an integer of 0 or greater and 4 or less, m pieces of R 3 's are each independently a methyl group or an ethyl group, n is an integer of 0 or more and 5 or less, and n pieces of R 4 's are each independently a methyl group or an ethyl group, where a plurality of methyl groups and/or ethyl groups may be linked to each other to form a ring.
  2. The electrophotographic photoreceptor according to claim 1, wherein a relationship of 0.5 ≤ (BP1 × MP1 + BP2 × MP2)/(BP3 × MP3 + BP4 × MP4) ≤ 2.5 is satisfied.
  3. The electrophotographic photoreceptor according to claim 1 or 2, wherein the antioxidant includes a hindered phenolic compound.
  4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the first resin is a polyarylate resin, and the second resin is a polycarbonate resin.
  5. The electrophotographic photoreceptor according to claim 4, wherein a proportion of the polyarylate resin in a total amount of the polyarylate resin and the polycarbonate resin contained in the outermost surface layer is 25% by mass or more and 75% by mass or less.
  6. The electrophotographic photoreceptor according to claim 4 or 5, wherein the polyarylate resin has at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by Formula (A1), a dicarboxylic acid unit (A2) represented by Formula (A2), a dicarboxylic acid unit (A3) represented by Formula (A3), a dicarboxylic acid unit (A4) represented by Formula (A4), and a dicarboxylic acid unit (A5) represented by Formula (A5), in Formula (A1), n 101 is an integer of 0 or greater and 4 or less, and n 101 pieces of Ra 101 's are each independently an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, in Formula (A2), n 201 and n 202 are each independently an integer of 0 or greater and 4 or less, and n 201 pieces of Ra 201 's and n 202 pieces of Ra 202 's are each independently an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, in Formula (A3), n 301 and n 302 are each independently an integer of 0 or greater and 4 or less, and n 301 pieces of Ra 301 's and n 302 pieces of Ra 302 's are each independently an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, in Formula (A4), n 401 is an integer of 0 or greater and 6 or less, and n 401 pieces of Ra 401 's are each independently an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, in Formula (A5), n 501 , n 502 , and n 503 are each independently an integer of 0 or greater and 4 or less, and n 501 pieces of Ra 501 's, n 502 pieces of Ra 502 's, and n 503 pieces of Ra 503 's are each independently an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.
  7. The electrophotographic photoreceptor according to any one of claims 4 to 6, wherein the polyarylate resin has at least one selected from the group consisting of a diol unit (B1) represented by Formula (B1), a diol unit (B2) represented by Formula (B2), a diol unit (B3) represented by Formula (B3), a diol unit (B4) represented by Formula (B4), a diol unit (B5) represented by Formula (B5), a diol unit (B6) represented by Formula (B6), a diol unit (B7) represented by Formula (B7), and a diol unit (B8) represented by Formula (B8), in Formula (B1), Rb 101 is a branched alkyl group having 4 or more and 20 or less carbon atoms, Rb 201 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb 401 , Rb 501 , Rb 801 , and Rb 901 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B2), Rb 102 is a linear alkyl group having 4 or more and 20 or less carbon atoms, Rb 202 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb 402 , Rb 502 , Rb 802 , and Rb 902 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B3), Rb 113 and Rb 213 are each independently a hydrogen atom, a linear alkyl group having 1 or more and 3 or less carbon atoms, an alkoxy group having 1 or more and 4 or less carbon atoms, or a halogen atom, d is an integer of 7 or greater and 15 or less, and Rb 403 , Rb 503 , Rb 803 , and Rb 903 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B4), Rb 104 and Rb 204 are each independently a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb 404 , Rb 504 , Rb 804 , and Rb 904 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B5), Ar 105 is 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, Rb 205 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, and Rb 405 , Rb 505 , Rb 805 , and Rb 905 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B6), Rb 116 and Rb 216 are each independently a hydrogen atom, a linear alkyl group having 1 or more and 3 or less carbon atoms, an alkoxy group having 1 or more and 4 or less carbon atoms, or a halogen atom, e is an integer of 4 or greater and 6 or less, and Rb 406 , Rb 506 , Rb 806 , and Rb 906 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B7), Rb 407 , Rb 507 , Rb 807 , and Rb 907 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom, in Formula (B8), Rb 408 , Rb 508 , Rb 808 , and Rb 908 are each independently a hydrogen atom, an alkyl group having 1 or more and 4 or less carbon atoms, an alkoxy group having 1 or more and 6 or less carbon atoms, or a halogen atom.
  8. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the photosensitive layer includes a charge generation layer and a charge transport layer, and the charge transport layer is the outermost surface layer.
  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 device that charges a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device 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 device that transfers the toner image to a surface of a recording medium.
  11. The image forming apparatus according to claim 10, further comprising: a cleaning device that has a cleaning blade coming into contact with the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor.
  12. The image forming apparatus according to claim 11, wherein a contact portion of the cleaning blade coming into contact with the electrophotographic photoreceptor contains a polyurethane rubber obtained by polymerizing at least a polyol component and a polyisocyanate component, and the contact portion is formed of a member having a ratio M100/Re of a 100% modulus M100 (MPa) to a rebound resilience Re (%) of 0.25 or more, the rebound resilience Re of less than 25%, and a tensile stress at a 200% strain of 15 MPa or more.
  13. The image forming apparatus according to claim 12, wherein the ratio M100/Re is 0.28 or more and 1.0 or less.

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 JP2001-265021A discloses an electrophotographic photoreceptor in which a polyester resin having a biphenyl structure as a repeating unit is contained in a photosensitive layer. JP2023-121553A discloses a photoreceptor in which a charge transport layer contains at least one of a polyester resin having a constitutional unit having an aromatic ring or a polycarbonate resin having a constitutional unit having an aromatic ring. JP2024-011918A discloses an electrophotographic photoreceptor in which a charge transport layer contains a charge transport material, a polyester resin having a predetermined aromatic structure, and a polycarbonate resin. JP2023-106209A discloses a cleaning blade in which a contact portion coming into contact with a member to be cleaned contains a polyurethane rubber obtained by polymerizing at least a polyol component and a polyisocyanate component, in which a ratio M100/Re of a 100% modulus M100 (MPa) to a rebound resilience Re (%) is 0.25 or more, the rebound resilience Re is less than 25%, and a tensile stress at a 200% strain is 15 MPa or more. SUMMARY OF THE INVENTION An object of the present disclosure is to provide an electrophotographic photoreceptor in which ghosts and density unevenness are unlikely to occur in an image. Specific methods for achieving the above-described object include the following aspects. Each formula is the same as the formula having the same number described later. <1> According to a first aspect of the present disclosure, there is provided an electrophotographic photoreceptor including a conductive substrate, and a photosensitive layer disposed on the conductive substrate, in which an outermost surface layer contains a first resin, a second resin, a charge transport material, and an antioxidant, at least one of the first resin or the second resin has a constitutional unit including a biphenyl represented by Formula (BPa), at least one of the charge transport material or the antioxidant has at least one of the biphenyl represented by Formula (BPa) or a biphenyl represented by Formula (BPb) in a molecule, and in a case where the number of the biphenyls per unit molecular weight of each of the first resin, the second resin, the charge transport material, and the antioxidant is denoted by BP1, BP2, BP3, and BP4, and in a case where a proportion (% by mass) of each of the first resin, the second resin, the charge transport material, and the antioxidant in a total amount of the first resin, the second resin, the charge transport material, and the antioxidant is denoted by MP1, MP2, MP3, and MP4, a relationship of 0.0 ≤ (BP1 × MP1 + BP2 × MP2)/(BP3 × MP3 + BP4 × MP4) ≤ 3.0 is satisfied.<2> According to a second aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <1>, in which a relationship of 0.5 ≤ (BP1 × MP1 + BP2 × MP2)/(BP3 × MP3 + BP4 × MP4) ≤ 2.5 may be satisfied.<3> According to a third aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <1> or <2>, in which the antioxidant may include a hindered phenolic compound.<4> According to a fourth aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to any one of <1> to <3>, in which the first resin may be a polyarylate resin, and the second resin may be a polycarbonate resin.<5> According to a fifth aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <4>, in which a proportion of the polyarylate resin in a total amount of the polyarylate resin and the polycarbonate resin contained in the outermost surface layer may be 25% by mass or more and 75% by mass or less.<6> According to a sixth aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <4> or <5>, in which the polyarylate resin may have at least one selected from the group consisting of a dicarboxylic acid unit (A1) represented by Formula (A1), a dicarboxylic acid unit (A2) represented by Formula (A2), a dicarboxylic acid unit (A3) represented by Formula (A3), a dicarboxylic acid unit (A4) represented by Formula (A4), and a dicarboxylic acid unit (A5) represented by Formula (A5).<7> According to a seventh aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to any one of <4> to <6>, in which the polyarylate resin may have at least one selected from the group consisting of a diol unit (B1) represented by Formula (B1), a diol unit (B2) represented by Formula (B2), a diol unit (B3) represented by Formula (B3), a diol unit (B4) represented by Formula (B4), a diol unit (B5) represented by Formula (B5), a diol unit (B6) represented by Formula (B6), a diol unit (B7) r