Undercoat Layer Ghost Reduction via Silicone Oil and Particles
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Solution Overview
Problem
Current electrophotographic photosensitive members face challenges with increased sensitivity leading to ghost phenomena and image defects due to charge retention, despite advancements in charge generation materials and undercoat layer techniques.
Innovation Solution
An electrophotographic photosensitive member is developed with an undercoat layer containing a cured product of a composition including an electron transport material, particles with an average primary particle size of 10 nm or more, and silicone oil, where the particle content is between 3% to 20% by mass and silicone oil content is between 0.01% to 10% by mass, along with specific compounds represented by formulas (A) and (B), to enhance the undercoat layer's cyclic strength and reduce internal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charge generation materials with higher sensitivity are used, then sensitivity is improved, but charges remain in the charge generation layer causing ghost phenomena
Solution Approach 1:
An undercoat layer is introduced as an intermediary between the support and the charge generation layer. This undercoat layer contains an electron transport material that facilitates smooth electron migration from the charge generation layer to the support, preventing charge accumulation and ghost phenomena while maintaining high sensitivity of the charge generation materials
Solution Approach 2:
The undercoat layer uses a composite material system combining an electron transport material with a curable material that has low solubility in the charge generation layer solvent. This composite structure prevents elution of the electron transport material during charge generation layer formation while ensuring effective electron transport to suppress charge remaining
2Reliability
If an electron transport material is incorporated in the undercoat layer, then charge migration is improved, but the electron transport material may elute during charge generation layer formation
Solution Approach 1:
The solubility parameter of the undercoat layer material is changed by using a curable material that is hardly soluble in the solvent of the charge generation layer coating liquid. This parameter change prevents elution of the electron transport material during charge generation layer formation while maintaining its electron transport function
Solution Approach 2:
The undercoat layer is designed with specific local properties - using a curable material with low solubility in the charge generation layer solvent in the region where electron transport material is present. This local quality adjustment prevents material elution at the interface while maintaining electron transport capability
3Strength
If the undercoat layer is formed with curable material and particles, then cyclic strength is improved, but internal stress increases causing image defects
Solution Approach 1:
The particle size parameter is optimized to 10 nm or more, which provides sufficient cyclic strength while minimizing internal stress. This parameter adjustment resolves the contradiction between strength enhancement and stress reduction
Solution Approach 2:
The incorporation of particles with 10 nm or more average primary particle size creates a microstructure that enhances cyclic strength while the specific size range helps manage internal stress, preventing image defects like black spots
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 effectively reduces ghost phenomena and maintains sensitivity, improving long-term durability and image quality by relieving internal stress and inhibiting electron transfer in the undercoat layer.
Implementation Method 1
a cured product of a composition containing an electron transport material, a particle having an average primary particle size of 10 nm or more, and a silicone oil
Implementation Method 2
A technique for achieving smooth migration of electrons from the charge generation layer side to the support side by incorporating an electron transport material in an undercoat layer
Implementation Method 3
a step of forming an undercoat layer by drying a coating film of a coating liquid for an undercoat layer by heating
Data Source
AI summary
An electrophotographic photosensitive member includes an undercoat layer, a charge generation layer, and a charge transport layer in this order. The undercoat layer contains a cured product of a composition containing an electron transport material, a particle having an average primary particle size of 10 nm or more, and a silicone oil. A content of the particle in the undercoat layer is 3% by mass or more and 20% by mass or less. A content of the silicone oil in the undercoat layer is 0.01% by mass or more and 10% by mass or less relative to the content of the particle.