Electrophotographic Photosensitive Member Copolymer Surface Layer

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Solution Overview

Problem

Electrophotographic photosensitive members in color electrophotographic apparatuses face issues with streak-like image defects due to degradation in lubricating properties and fluctuations in electrical potential, leading to image quality issues during repetitive use.

Innovation Solution

The electrophotographic photosensitive member incorporates a surface layer with a cured material that is a copolymer of a hole transport compound having a chain-polymerizable functional group and a compound with a long-chain alkyl group, enhancing abrasion resistance and maintaining lubricity through polymerization reactions, which stabilizes the cleaning device behavior and reduces image defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a surface layer is formed using a hole transport material with polymerizable functional groups and surfactant (PTL 1), then abrasion resistance is improved, but lubricating property degrades over time causing image defects

Engineering Contradiction:
Improveabrasion resistanceVSAvoidlubricating property
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The surface layer uses a composite material system combining hole transport material with polymerizable functional groups and surfactant having reactive functional groups. These materials undergo polymerization reactions to form a cured material that integrates both abrasion resistance and lubricating properties into a single durable surface layer structure

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the chemical state of the surface layer materials by transforming them from uncured monomeric/oligomeric forms to cured polymeric forms through polymerization reactions. This parameter change (from uncured to cured) stabilizes both the mechanical strength for abrasion resistance and the chemical composition for maintaining lubricating properties

Inventive Principle:
Principle #35Parameter changes

2Reliability

If lubricating material is mixed in the surface layer (PTL 2), then transferability and cleanability are improved, but abrasion resistance decreases due to material removal

Engineering Contradiction:
Improvetransferability and cleanabilityVSAvoidabrasion resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention merges the functions of hole transport material and lubricating material into a single integrated surface layer. The hole transport material provides the structural backbone for abrasion resistance while the incorporated surfactant/lubricating material provides transferability and cleanability, with both functions working together in a unified polymerized matrix

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The surface layer employs a composite material where hole transport material with polymerizable groups forms the structural framework providing durability, while surfactant or lubricating material with reactive functional groups is incorporated to provide transferability and cleanability. The polymerization process binds these components into a cohesive structure where neither function compromises the other

Inventive Principle:
Principle #40Composite materials

3Productivity

If the electrophotographic photosensitive member is used repetitively, then productivity is improved, but image quality degrades due to electrical potential fluctuations and surface flaws

Engineering Contradiction:
Improverepetitive use capabilityVSAvoidimage quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention performs preliminary action by pre-forming a stable, polymerized surface layer with appropriate lubricating properties before the electrophotographic photosensitive member enters repetitive use. This pre-established surface layer prevents future degradation, electrical potential fluctuations, and image defects that would otherwise occur during repetitive operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The polymerized surface layer acts as a protective cushion that anticipates and prevents damage during repetitive use. The cured material provides a buffer against mechanical wear, electrical potential instability, and surface flaws, cushioning the underlying photoconductive layer from degradation effects before they can occur

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 streak-like image defects and maintains image quality by ensuring appropriate lubricity and durability of the electrophotographic photosensitive member, even during repetitive use, by incorporating a copolymer surface layer that stabilizes the cleaning device and enhances the strength of the surface layer.

Implementation Method 1

a cured material, and the cured material is a copolymer of a hole transport compound having a chain-polymerizable functional group

Methodology Applied
Scientific EffectChain-polymerization: Photopolymerisation

Implementation Method 2

the cured material is a copolymer of a hole transport compound having a chain-polymerizable functional group and a compound denoted by formula (I) below

Methodology Applied
Scientific EffectCopolymerization: Photopolymerisation

Data Source

PatentEP3451067B1Electrophotographic photosensitive body, method for producing electrophotographic photosensitive body, process cartridge and electrophotographic apparatus
Publication Date: 2020.09.30 CANON KK
  • EP3451067B1 patent drawingFigure 1~2
  • EP3451067B1 patent drawingFigure 3
  • EP3451067B1 patent drawingFigure 4(a)~4(c)

AI summary

An electrophotographic photosensitive member, in which occurrences of image defects are suppressed, and a method for manufacturing the electrophotographic photosensitive member are provided. In addition, a process cartridge and an electrophotographic apparatus, which include the electrophotographic photosensitive member, are provided. The surface layer of the electrophotographic photosensitive member contains a cured material, and the cured material is a copolymer of a hole transport compound having a chain-polymerizable functional group and a vinyl ester compound containing a long-chain alkyl group.