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US-12624159-B2 - Polyarylate resin and electrophotographic photosensitive member

US12624159B2US 12624159 B2US12624159 B2US 12624159B2US-12624159-B2

Abstract

A polyarylate resin includes repeating units represented by formulas (1), (2), (3), and (4). A percentage of the number of repeats of the repeating unit represented by formula (3) relative to the total number of repeats of the respective repeating units represented by formulas (1) and (3) is greater than 0% and less than 20%. In formula (1), R 1 and R 2 each represent, independently of one another, a hydrogen atom or a methyl group and X represents a divalent group represented by formula (X1) or (X2). In formula (2), W represents, a divalent group represented by formula (W1) or (W2).

Inventors

  • Jun Azuma
  • Keiji Maruo
  • Kenji KITAGUCHI

Assignees

  • KYOCERA DOCUMENT SOLUTIONS INC.

Dates

Publication Date
20260512
Application Date
20220119
Priority Date
20210126

Claims (12)

  1. 1 . A polyarylate resin comprising repeating units represented by formulas (1), (2), (3), and (4), wherein a percentage of a number of repeats of the repeating unit represented by the formula (3) relative to a total number of repeats of the respective repeating units represented by the formulas (1) and (3) is greater than 0% and less than 20%, where in the formula (1), R 1 and R 2 each represent, independently of one another, a hydrogen atom or a methyl group and X represents a divalent group represented by formula (X1) or (X2), and in the formula (2), W represents a divalent group represented by formula (W1) or (W2), where in the formula (X1), t represents an integer of at least 1 and no greater than 3 and * represents a bond, and in the formula (X2), R 3 and R 4 each represent a hydrogen atom or an alkyl group with a carbon number of at least 1 and no greater than 4, R 3 and R 4 represent groups different from each other, and * represents a bond, and in the formulas (W1) and (W2), * represents a bond.
  2. 2 . The polyarylate resin according to claim 1 , wherein in the formula (1), R 1 and R 2 each represent a methyl group and X represents a divalent group represented by the formula (X1).
  3. 3 . The polyarylate resin according to claim 1 , wherein the repeating unit represented by the formula (1) is a repeating unit represented by formula (1-1):
  4. 4 . The polyarylate resin according to claim 1 , wherein the repeating unit represented by the formula (1) is a repeating unit represented by formula (1-1), and the repeating unit represented by the formula (2) is a repeating unit represented by formula (2-1):
  5. 5 . The polyarylate resin according to claim 1 , wherein the repeating unit represented by the formula (1) is a repeating unit represented by formula (1-1), and the repeating unit represented by the formula (2) is a repeating unit represented by formula (2-2):
  6. 6 . The polyarylate resin according to claim 1 , wherein in the formula (1), R 1 and R 2 each represent a hydrogen atom and X represents a divalent group represented by the formula (X2).
  7. 7 . The polyarylate resin according to claim 1 , wherein the repeating unit represented by the formula (1) is a repeating unit represented by formula (1-2):
  8. 8 . The polyarylate resin according to claim 1 , wherein the repeating unit represented by the formula (1) is a repeating unit represented by formula (1-2), and the repeating unit represented by the formula (2) is a repeating unit represented by formula (2-1):
  9. 9 . An electrophotographic photosensitive member comprising: a conductive substrate; and a photosensitive layer, wherein the photosensitive layer contains a charge generating material, a hole transport material, and a binder resin, and the binder resin includes the polyarylate resin according to claim 1 .
  10. 10 . The electrophotographic photosensitive member according to claim 9 , wherein the hole transport material includes a compound represented by formula (20), (21), or (22): where in the formula (20): R 21 and R 22 each represent, independently of one another, a phenyl group, an alkyl group with a carbon number of at least 1 and no greater than 8, or an alkoxy group with a carbon number of at least 1 and no greater than 8; R 23 to R 29 each represent, independently of one another, a hydrogen atom, an alkyl group with a carbon number of at least 1 and no greater than 8, a phenyl group optionally substituted with an alkyl group with a carbon number of at least 1 and no greater than 8, or an alkoxy group with a carbon number of at least 1 and no greater than 8; any adjacent two of chemical groups R 21 to R 29 may be bonded to form a ring; and a1 and a2 each represent, independently of one another, an integer of at least 0 and no greater than 5, in the formula (21): R 31 to R 36 each represent, independently of one another, a phenyl group or an alkyl group with a carbon number of at least 1 and no greater than 8; R 37 and R 38 each represent, independently of one another, a hydrogen atom, a phenyl group, or an alkyl group with a carbon number of at least 1 and no greater than 8; b1, b2, b3, and b4 each represent, independently of one another, an integer of at least 0 and no greater than 5; b5 and b6 each represent, independently of one another, an integer of at least 0 and no greater than 4; and d and e each represent, independently of one another, 0 or 1, and in the formula (22): R 41 to R 46 each represent, independently of one another, a phenyl group, an alkyl group with a carbon number of at least 1 and no greater than 8, or an alkoxy group with a carbon number of at least 1 and no greater than 8; f1, f2, f4, and f5 each represent, independently of one another, an integer of at least 0 and no greater than 5; and f3 and f6 each represent, independently of one another, an integer of at least 0 and no greater than 4.
  11. 11 . The electrophotographic photosensitive member according to claim 9 , wherein the hole transport material includes a compound represented by formula (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), or (HTM-6):
  12. 12 . The electrophotographic photosensitive member according to claim 9 , wherein the photosensitive layer includes a charge generating layer containing the charge generating material and a charge transport layer containing the hole transport material and the binder resin, and the charge transport layer is a single layer serving as an outermost layer.

Description

TECHNICAL FIELD The present invention relates to a polyarylate resin and an electrophotographic photosensitive member. BACKGROUND ART Electrophotographic photosensitive members are used as image bearing members in electrographic image forming apparatuses (e.g., printers and multifunction peripherals). An electrophotographic photosensitive member includes a photosensitive layer. Examples of the electrophotographic photosensitive member include a single-layer electrophotographic photosensitive member and a multi-layer electrophotographic photosensitive member. The single-layer electrophotographic photosensitive member includes a single-layer photosensitive layer having a charge generation function and an electrical charge transport function. The multi-layer electrophotographic photosensitive member includes a photosensitive layer including a charge generating layer having a charge generation function and a charge transport layer having a charge transport function. Patent Literature 1 discloses an electrophotographic photosensitive member including a surface layer containing a polyarylate resin obtained from a divalent phenol component and a divalent carboxylic acid component represented by the following formula. CITATION LIST Patent Literature Patent Literature 1 Japanese Patent Application Laid-Open Publication No. 10-20514 SUMMARY OF INVENTION Technical Problem However, the electrophotographic photosensitive member disclosed in Patent Literature 1 has insufficient abrasion resistance. Furthermore, the present inventors studied to find that the electrophotographic photosensitive member disclosed in Patent Literature 1 also has insufficient solubility of a binder resin in a solvent and insufficient sensitivity after repetition of charging and light exposure. The present invention has been made in view of the foregoing and has its object of providing a polyarylate resin that has excellent solubility in a solvent and that increases sensitivity and abrasion resistance after repetition of charging and light exposure of an electrophotographic photosensitive member when a photosensitive layer thereof contains the polyarylate resin. In the following, “sensitivity after repetition of charging and light exposure” may be referred to as “repetitive sensitivity”. Furthermore, another object of the present invention is to provide an electrophotographic photosensitive member that includes a favorably formed photosensitive layer and that has excellent abrasion resistance and repetitive sensitivity. Solution to Problem A polyarylate resin according to the present invention includes repeating units represented by formulas (1), (2), (3) and (4). A percentage of a number of repeats of the repeating unit represented by the formula (3) relative to a total number of repeats of the respective repeating units represented by the formulas (1) and (3) is greater than 0% and less than 20%. In the formula (1), R1 and R2 each represent, independently of one another, a hydrogen atom or a methyl group and X represents a divalent group represented by formula (X1) or (X2). In the formula (2), W represents a divalent group represented by formula (W1) or (W2). In the formula (X1), t represents an integer of at least 1 and no greater than 3 and * represents a bond. In the formula (X2), R3 and R4 each represent a hydrogen atom or an alkyl group with a carbon number of at least 1 and no greater than 4, R3 and R4 represent groups different from each other, and * represents a bond. In the formulas (W1) and (W2), * represents a bond. An electrophotographic photosensitive member according to the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating material, a hole transport material, and a binder resin. The binder resin includes the aforementioned polyarylate resin. Advantageous Effects of Invention The polyarylate resin of the present invention has excellent solubility in a solvent and can increase repetitive sensitivity and abrasion resistance of an electrophotographic photosensitive member when a photosensitive layer thereof contains the polyarylate resin. The electrophotographic photosensitive member of the present invention can have a favorably formed photosensitive layer and is excellent in repetitive sensitivity and abrasion resistance. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a partial cross-sectional view of a multi-layer electrophotographic photosensitive member that is an example of an electrophotographic photosensitive member according to a second embodiment of the present invention. FIG. 2 is a partial cross-sectional view of a multi-layer electrophotographic photosensitive member that is an example of the electrophotographic photosensitive member according to the second embodiment of the present invention. FIG. 3 is a partial cross-sectional view of a multi-layer electrophotographic photosensitive member that is an example of the electrophotographic photosensit