Crystal-Controlled Photoreceptor Undercoat for Charge Retention

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Solution Overview

Problem

Electrophotographic photoreceptors suffer from decreased charge maintainability due to suboptimal electron transport properties, particularly when the full width at half maximum (FWHM) of the X-ray diffraction spectrum in the undercoat layer exceeds 5.0° or the crystal density of the electron transport material is less than 1.62 g/cm³.

Innovation Solution

The photoreceptor incorporates an undercoat layer containing a binder resin and an electron transport material with a crystal density of 1.62 g/cm³ or greater and a FWHM of 5.0° or less, utilizing an electron transport material represented by General Formula (P) to enhance electron transport properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electron transport properties are improved by adjusting the undercoat layer composition, then the charge maintainability decreases

Engineering Contradiction:
Improvecharge maintainabilityVSAvoidelectron transport properties
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the crystal density (≥1.62 g/cm³) and XRD spectrum FWHM (≤5.0°) of the electron transport material in the undercoat layer. These parameter optimizations enable the material to achieve both excellent electron transport properties and high charge maintainability, resolving the contradiction between the two performance aspects.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining the electron transport material with a binder resin in specific proportions within the undercoat layer. This composite structure allows the electron transport material to provide high electron mobility while the binder resin maintains structural integrity and charge stability, thus achieving both improved electron transport and maintained charge maintainability.

Inventive Principle:
Principle #40Composite materials

2Reliability

If the FWHM of the X-ray diffraction spectrum exceeds 5.0° or crystal density is less than 1.62 g/cm³, then electron transport properties improve, but charge maintainability decreases

Engineering Contradiction:
Improvecharge maintainabilityVSAvoidcrystal density and FWHM control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent establishes specific parameter thresholds (crystal density ≥1.62 g/cm³ and FWHM ≤5.0°) for the electron transport material to achieve optimal performance. By controlling these parameters within defined ranges, the patent ensures both excellent electron transport properties and high charge maintainability, transforming the manufacturing precision requirements into performance benefits.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration improves electron transport properties and reduces dark decay, resulting in enhanced charge maintainability and stability of the photoreceptor.

Implementation Method 1

the undercoat layer contains a binder resin and an electron transport material with a crystal density of 1.62 g/cm³ or greater and a FWHM of 5.0° or less, utilizing an electron transport material represented by General Formula (P) to enhance electron transport properties

Methodology Applied
Scientific EffectElectron transport: Conduction (electrical)

Implementation Method 2

the full width at half maximum (FWHM) of the maximum intensity peak in an X-ray diffraction spectrum measured in a thickness direction of the undercoat layer

Methodology Applied
Scientific EffectX-ray diffraction: X-Ray

Implementation Method 3

X-ray diffraction spectrum measured in a thickness direction

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentEP4528381B1Electrophotographic photoreceptor, process cartridge, and image forming apparatus
Publication Date: 2025.10.15 FUJIFILM BUSINESS INNOVATION CORP
  • EP4528381B1 patent drawingFigure 1~2
  • EP4528381B1 patent drawingFigure 3
  • EP4528381B1 patent drawing

AI summary

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer that is provided on the conductive substrate, and a photosensitive layer provided on the undercoat layer, in which the undercoat layer contains a binder resin and an electron transport material having a crystal density of 1.62 g/cm3 or greater, and a full width at half maximum (FWHM) of a maximum intensity peak in an X-ray diffraction spectrum measured in a thickness direction is 5.0 or less.