Photoreceptor Layer Thickness Control to Prevent Protective Coating Peeling

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Solution Overview

Problem

The surface protective layer of electrophotographic photoreceptors is prone to peeling off from the charge transport layer, particularly when the film thicknesses of either layer exceed certain thresholds, leading to coating defects and image quality issues.

Innovation Solution

The photoreceptor is designed with a charge transport layer thickness of 8 µm to 25 µm and a surface protective layer thickness of 10 µm or less, using a resin with specific molecular structures to reduce interfacial stress, thereby preventing peeling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the film thickness of the charge transport layer is increased to improve charge transport performance, then the charge transport ability is enhanced, but the surface protective layer becomes prone to peeling off

Engineering Contradiction:
Improvecharge transport performanceVSAvoidadhesion between surface protective layer and charge transport layer
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent optimizes the film thickness parameter of the charge transport layer to a specific range (5 µm to 20 µm) to balance charge transport performance and adhesion stability. This parameter change prevents the surface protective layer from peeling while maintaining effective charge transport, resolving the contradiction between performance and stability.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the film thickness of the surface protective layer is increased to improve protective function, then the protection ability is enhanced, but the surface protective layer becomes prone to peeling off

Engineering Contradiction:
Improveprotective functionVSAvoidadhesion between surface protective layer and charge transport layer
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent optimizes the film thickness parameter of the surface protective layer to a specific range (1 µm to 10 µm) to balance protective function and adhesion stability. This parameter change ensures sufficient protection while preventing peeling issues, resolving the contradiction between strength and stability.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the film thickness of the charge transport layer is increased to improve charge transport, then the transport efficiency is enhanced, but coating uniformity deteriorates

Engineering Contradiction:
Improvecharge transport efficiencyVSAvoidcoating uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent sets the charge transport layer thickness within a controlled range (5 µm to 20 µm) to ensure both adequate charge transport efficiency and coating uniformity. This parameter optimization prevents coating defects while maintaining transport performance.

Inventive Principle:
Principle #35Parameter changes

4Duration of action of stationary object

If the film thickness of the surface protective layer is increased to improve protection, then the durability is enhanced, but image quality stability deteriorates

Engineering Contradiction:
ImprovedurabilityVSAvoidimage quality stability
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent optimizes the surface protective layer thickness to (1 µm to 10 µm) to balance durability and image quality stability. This parameter change ensures long-term durability while preventing image quality degradation, resolving the contradiction between duration and reliability.

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 design effectively suppresses peeling of the surface protective layer, enhances coating uniformity, and maintains image quality stability by reducing interfacial stress and coating defects.

Implementation Method 1

using a resin with specific molecular structures to reduce interfacial stress, thereby preventing peeling

Methodology Applied
Scientific EffectInterfacial stress reduction:

Data Source

PatentEP4530725B1Electrophotographic photoreceptor, process cartridge, and image forming apparatus
Publication Date: 2025.12.03 FUJIFILM BUSINESS INNOVATION CORP
  • EP4530725B1 patent drawingFigure 1~2
  • EP4530725B1 patent drawingFigure 3
  • EP4530725B1 patent drawing

AI summary

An electrophotographic photoreceptor includes a conductive substrate, a charge generation layer provided on the conductive substrate, a charge transport layer provided on the charge generation layer, and a surface protective layer provided on the charge transport layer, in which the charge transport layer has a film thickness of 8 µm or greater and 25 µm or less, and the surface protective layer is a cured film of a composition, having a film thickness of 10 µm or less and containing a resin (X) that has at least one of a unit represented by Formula (XI) or a unit represented by Formula (X2) and a reactive group-containing charge transport material that contains a reactive group and a charge-transporting skeleton in an identical molecule, in Formula (X1), R101, R102, and R103 each independently represent a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms, L101 represents a single bond, an alkylene group having 1 or more and 5 or less carbon atoms, -O-, -C(=O)-, -C(=O)O-, an aromatic ring that may have a substituent, or a combination thereof, L102 represents a single bond, an alkylene group having 1 or more and 5 or less carbon atoms, -O-, -C(=O)-, -C(=O)O-, or a combination thereof, R104 and R105 each independently represent an alkyl group having 1 or more and 5 or less carbon atoms, n represents an integer of 0 or greater and 300 or less, R106, R107, and R108 each independently represent an alkyl group having 1 or more and 5 or less carbon atoms or -O-[Si(R109)(R110)O]m-Si(R111)(R112)(R113), R109, R110, R111, R112, and R113 each independently represent an alkyl group having 1 or more and 5 or less carbon atoms, and m represents an integer of 0 or greater and 20 or less, in Formula (X2), R201, R202, and R203 each independently represent a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms, L201 represents a single bond, an alkylene group having 1 or more and 5 or less carbon atoms, -O-, -C(=O)-, -C(=O)O-, an aromatic ring that may have a substituent, or a combination thereof, L202 represents a single bond, an alkylene group having 1 or more and 5 or less carbon atoms, -O-, -C(=O)-, -C(=O)O-, or a combination thereof, and R204 is an alkyl group having 6 or more and 30 or less carbon atoms.