Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

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Solution Overview

Problem

Existing electrophotographic photosensitive members experience insufficient suppression of residual potential increase during high-speed and long-duration processes, despite incorporating metal oxide and polyfunctional charge-transporting monomer technologies.

Innovation Solution

Incorporation of a cured product in the surface layer containing a charge-transportable compound, electroconductive particles, and an organic salt formed of an organic cation and an anion, which assists in charge migration and reduces residual potential.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal oxide is incorporated into the surface layer to improve abrasion resistance, then mechanical durability is improved, but residual potential increases during high-speed and long-duration processes

Engineering Contradiction:

Improveabrasion resistanceVSAvoidresidual potential control

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The surface layer uses a composite material system combining metal oxide particles with a polymer matrix containing charge-transporting substances and polymerizable monomers. This composite structure provides both the mechanical durability from metal oxide and the charge dissipation properties from the polymer matrix, resolving the contradiction between abrasion resistance and residual potential control.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition parameters of the surface layer by incorporating specific ratios of metal oxide, charge-transporting substances, and polymerizable monomers. This parameter optimization allows the surface layer to simultaneously achieve high abrasion resistance and effective charge dissipation, preventing residual potential increase during extended operation.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If polyfunctional charge-transporting monomer is incorporated into the surface layer to improve charge transport, then electrophotographic performance is improved, but residual potential still increases during high-speed and long-duration processes

Engineering Contradiction:

Improveelectrophotographic performanceVSAvoidresidual potential control

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent utilizes the phase transition from monomer to polymer through photopolymerization or thermal curing. The polymerizable functional groups in the charge-transporting monomer allow the material to transition from a liquid or soft solid state to a crosslinked polymer network, providing both excellent charge transport properties and enhanced stability to prevent charge accumulation during prolonged operation.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The polymerizable functional groups act as intermediaries that bridge the charge-transporting monomer molecules, forming a crosslinked network structure. This intermediary polymerization process creates a stable matrix that maintains efficient charge transport while preventing charge retention, thus resolving the residual potential issue during high-speed and long-duration processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Duration of action of stationary object

If the surface layer is optimized for mechanical durability, then lifetime is extended, but charge dissipation capability deteriorates

Engineering Contradiction:

ImprovelifetimeVSAvoidcharge dissipation capability

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent optimizes the chemical composition parameters of the surface layer by incorporating specific ratios of metal oxide, charge-transporting substances, and polymerizable monomers. This parameter optimization allows the surface layer to simultaneously achieve high abrasion resistance and effective charge dissipation, preventing residual potential increase during extended operation.

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

Effectively suppresses the increase in residual potential, enhancing the mechanical durability and image quality of the electrophotographic photosensitive member.

Implementation Method 1

an organic salt having a polymerizable functional group, the organic salt being formed of: an organic cation; and at least one anion selected from the group consisting of: an organic anion; and an inorganic anion

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

a cured product of a composition containing: at least one selected from the group consisting of: a charge-transportable compound; and an electroconductive particle

Methodology Applied

Scientific EffectCharge transport: Conduction (electrical)

Data Source

PatentUS12449740B2Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Publication Date: 2025.10.21 CANON KK

AI summary

An electrophotographic photosensitive member includes a support, a photosensitive layer, and a surface layer. The surface layer includes a cured product of a composition containing an organic salt having a polymerizable functional group, and at least one of a charge-transportable compound or electroconductive particles. The organic salt is formed of an organic cation and at least one of BF4−, PF6−, (CF3SO2)2N−, CF3SO3−, (FSO2)N−, C2H5OSO3−, (CN)2N−, SCN−, CH3COO−, NO3−, Cl−, Br− or I−.