Search

EP-4741934-A1 - ELECTROPHOTOGRAPHIC PHOTORECEPTOR, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS

EP4741934A1EP 4741934 A1EP4741934 A1EP 4741934A1EP-4741934-A1

Abstract

An electrophotographic photoreceptor includes a conductive substrate, and a lamination-type photosensitive layer disposed on the conductive substrate and having a charge generation layer and a charge transport layer, in which the charge transport layer contains a polyarylate resin having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B), the charge generation layer contains, as a charge generation material, a chlorogallium phthalocyanine, and a value of a content of a binder resin to a total content of the binder resin and the charge generation material in the charge generation layer is more than 0.4 and less than 0.7, 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

  • TAKAOKA, KOHEI
  • IDE, KENTA
  • KIGOSHI, YOICHI
  • KANO, FUYUKI
  • SASAKI, TOMOYA
  • IWASAKI, MASAHIRO
  • OYAMADA, YUKI

Assignees

  • FUJIFILM Business Innovation Corp.

Dates

Publication Date
20260513
Application Date
20250429

Claims (9)

  1. An electrophotographic photoreceptor comprising: a conductive substrate; and a lamination-type photosensitive layer disposed on the conductive substrate and having a charge generation layer and a charge transport layer, wherein the charge transport layer contains a polyarylate resin having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B), the charge generation layer contains, as a charge generation material, a chlorogallium phthalocyanine, and a value of a content of a binder resin to a total content of the binder resin and the charge generation material in the charge generation layer is more than 0.4 and less than 0.7, 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 value of the content of the binder resin to the total content of the binder resin and the charge generation material in the charge generation layer is more than 0.43 and less than 0.60.
  3. The electrophotographic photoreceptor according to claim 1 or 2, wherein the dicarboxylic acid unit represented by Formula (A) includes 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 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.
  4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the diol unit represented by Formula (B) includes at least one selected from the group consisting of a diol unit (B 1) represented by Formula (B 1), 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 (B 1), 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.
  5. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the binder resin in the charge generation layer is a vinyl acetate-based resin or a polyvinyl butyral-based resin.
  6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein the binder resin in the charge generation layer is a vinyl chloride-vinyl acetate copolymer or a polyvinyl butyral resin.
  7. The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein the charge transport layer further contains a polycarbonate resin.
  8. A process cartridge comprising: the electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the process cartridge is attachable to and detachable from an image forming apparatus.
  9. An image forming apparatus comprising: the electrophotographic photoreceptor according to any one of claims 1 to 7; 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.

Description

BACKGROUND OF THE INVENTION (i) Field of the Invention The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. (ii) Description of Related Art JP2005-164936A discloses an electrophotographic photoreceptor including, in the following order, a charge generation layer and a charge transport layer on a support, in which at least one binder resin in the charge transport layer is a polyarylate resin, and the charge generation layer contains gallium phthalocyanine, and the charge transport layer contains an antioxidant in an amount of 5% by mass or more and less than 40% by mass with respect to a total mass of the binder resin in the charge transport layer, in an electrophotographic photoreceptor in which a film thickness of the charge transport layer is 28 µm or more. JP2024-11918A discloses an electrophotographic photoreceptor including a conductive substrate, and a lamination-type photosensitive layer disposed on the conductive substrate and having a charge generation layer and a charge transport layer, in which the charge transport layer contains a charge transport material, a polyester resin, and a polycarbonate resin, and the polyester resin includes a polyester resin having a specific structure. JP2003-202683A discloses an electrophotographic photoreceptor in which, in a lamination-type electrophotographic photoreceptor having at least two layers of a charge generation layer and a charge transport layer on a conductive support, the charge generation layer contains a phthalocyanine pigment and a polyarylate resin having a specific structure. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having excellent local deterioration suppression properties of electrical properties after long-term printing, as compared with a case where a value of a content of a binder resin to a total content of the binder resin and a charge generation material in a charge generation layer is 0.4 or less or 0.7 or more, the charge generation layer containing, as a charge generation material, a chlorogallium phthalocyanine, and the charge transport layer containing a polyarylate resin having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B). 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, and a lamination-type photosensitive layer disposed on the conductive substrate and having a charge generation layer and a charge transport layer, in which the charge transport layer contains a polyarylate resin having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B), the charge generation layer contains, as a charge generation material, a chlorogallium phthalocyanine, and a value of a content of a binder resin to a total content of the binder resin and the charge generation material in the charge generation layer is more than 0.4 and less than 0.7. 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 value of the content of the binder resin to the total content of the binder resin and the charge generation material in the charge generation layer may be more than 0.43 and less than 0.60.<3> According to a third aspect of the present disclosure, there is provided the electrophotographic photoreceptor according to <1> or <2>, in which the dicarboxylic acid unit represented by Formula (A) may include 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 Formula (A4), and a dicarboxylic acid unit (A5) represented by Formula (A5). In Formula (A1), n101 is an integer of 0 or greater and 4 or less, and n101 pieces of Ra101'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