Photosensitive Member Surface Layer for Ghost-Free Durability

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Solution Overview

Problem

Existing electrophotographic photosensitive members face durability issues and ghost phenomena due to surface layer stress, particularly when an electricity-eliminating step is omitted, and there is a need for a highly durable member that suppresses ghost images without such a step.

Innovation Solution

Incorporating a specific ratio of hole-transportable compounds with varying highest occupied molecular orbital (HOMO) energy levels in the surface layer, forming a crosslinked structure to moderate hole transfer and homogenize potential differences, eliminating the need for an electricity-eliminating step.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a curable resin is incorporated into the surface layer to improve durability, then durability is improved, but ghost phenomenon worsens

Engineering Contradiction:

ImprovedurabilityVSAvoidghost phenomenon

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the surface layer by incorporating specific hole-transporting compounds with controlled HOMO energy levels (within 0.05-0.30 eV difference) to resolve the contradiction between durability and ghost phenomenon suppression

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite surface layer material combining curable resin with specific hole-transporting compounds (formulas 1-3) to achieve both high durability through crosslinking and ghost phenomenon suppression through controlled charge transport properties

Inventive Principle:

Principle #40Composite materials

2Object-generated harmful factors

If an electricity-eliminating step is provided to suppress ghost phenomenon, then ghost phenomenon is suppressed, but device complexity increases

Engineering Contradiction:

Improveghost phenomenonVSAvoidprocess complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The surface layer itself performs the electricity-eliminating function through its inherent charge transport properties, eliminating the need for external electricity-eliminating steps or additional components

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the electricity-eliminating function from the process steps and integrates it into the surface layer material composition, removing the need for separate electricity-eliminating steps

Inventive Principle:

Principle #2Taking out (Extraction)

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

The solution effectively suppresses ghost images while maintaining high durability and electrical characteristics, even without an electricity-eliminating process, by using a copolymer of hole-transportable compounds with controlled HOMO energy differences.

Implementation Method 1

the second hole-transporting layer contains a copolymer of a composition containing a hole-transportable compound... to moderate hole transfer and homogenize potential differences

Methodology Applied

Scientific EffectHole transport: Conduction (electrical)

Implementation Method 2

when an energy value of a highest occupied molecular orbital of the hole-transportable compound... is represented by CTM1HOMO, and an energy value of a highest occupied molecular orbital of the at least one kind of hole-transportable compound... is represented by CTM2HOMO, the CTM1HOMO and the CTM2HOMO satisfy the following expression (II): 0.05 (eV)≤|CTM2HOMO|−|CTM1HOMO|≤0.30 (eV)

Methodology Applied

Scientific EffectEnergy level control through molecular orbital management:

Data Source

PatentUS12498645B2Electrophotographic photosensitive member, and electrophotographic apparatus and process cartridge each including the electrophotographic photosensitive member

Publication Date: 2025.12.16 CANON KK

AI summary

Provided is an electrophotographic photosensitive member including a support, a charge-generating layer, a first hole-transporting layer, and a second hole-transporting layer, wherein the second hole-transporting layer contains a hole-transportable compound represented by the formula (1) (mass: W1, energy value of the highest occupied molecular orbital: CTM1HOMO), and a hole-transportable compound represented by the formula (2) (mass: W2) and/or a hole-transportable compound represented by the formula (3) (mass: W3) (energy value of the highest occupied molecular orbital: CTM2HOMO), wherein a value calculated from the expression (I) is from 0.05% by mass to 5.0% by mass, and wherein the expression (II) is satisfied: (W2+W3)/(W1+W2+W3)×100 (% by mass) . . . Expression (I); and 0.05 (eV)≤|CTM2HOMO|−|CTM1HOMO|≤0.30 (eV) . . . (II).