Electrophotographic Photoreceptor Surface Layer Oxidation Control
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Solution Overview
Problem
Electrophotographic photoreceptors face challenges in maintaining stability in electrical characteristics and scratch resistance due to oxidation of charge transport materials and uneven distribution of resin particles, leading to reduced abrasion resistance and image quality.
Innovation Solution
A conductive substrate with a photosensitive layer and an outermost surface layer composed of a cured film containing reactive charge transport material, with a zinc stearate coverage of 5.0% or more and an oxygen permeability coefficient of 2.0×10^12 fm^2/Pa·s or more, which embeds zinc stearate in pores to enhance scratch resistance and reduce oxidation, using specific reactive charge transport materials and polycarbonate copolymers to prevent resin particle segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective layer is provided on the surface of an electrophotographic photoreceptor to improve strength, then scratch resistance is improved, but oxidation of charge transport materials occurs leading to reduced electrical characteristic stability
Solution Approach 1:
The protective layer is designed with a porous structure having specific pore volume (0.03 mL/g or more) and pore size (3 nm to 20 nm). These pores allow oxidation-resistant substances to penetrate and protect the charge transport material, while the layer itself provides scratch resistance. The porous structure enables dual functionality of protection and oxidation prevention.
Solution Approach 2:
The protective layer uses a composite material system combining a binder resin (polycarbonate copolymer with specific solubility parameter 10.5-12.5) and oxidation-resistant substance. This composite structure achieves both mechanical strength for scratch resistance and chemical resistance against oxidation, resolving the contradiction between strength and reliability.
2Reliability
If resin particles are distributed in the protective layer to improve electrical characteristics, then charge transport performance is improved, but uneven distribution occurs leading to reduced abrasion resistance
Solution Approach 1:
The solubility parameter of the binder resin is precisely controlled within 10.5-12.5 to optimize the compatibility and distribution of resin particles. This parameter control ensures uniform dispersion of charge transport material particles, preventing aggregation and maintaining both electrical characteristics and mechanical strength.
Solution Approach 2:
The protective layer is designed to achieve homogeneous distribution of resin particles and charge transport material throughout the layer. This uniform distribution prevents weak points that would reduce abrasion resistance while maintaining consistent electrical characteristics across the photoreceptor surface.
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 configuration results in improved stability of electrical characteristics and scratch resistance, preventing uneven load distribution and extending the lifetime of image forming apparatuses by reducing oxidation and enhancing mechanical strength.
Implementation Method 1
a zinc stearate coverage of the surface of the outermost surface layer is 5.0% or more
Implementation Method 2
an oxygen permeability coefficient of the outermost surface layer before coating with zinc stearate is 2.0×10^12 fm^2/Pa·s or more
Data Source
AI summary
An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein an outermost surface layer of the electrophotographic photoreceptor is composed of a cured film of a composition containing a reactive charge transport material, a zinc stearate coverage of the surface of the outermost surface layer is 5.0% or more, and an oxygen permeability coefficient of the outermost surface layer before coating with zinc stearate is 2.0×1012 fm2/Pa·s or more.