Photosensitive Member Protective Layer for Black Spot Suppression
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Solution Overview
Problem
Existing image-forming apparatuses face issues with the occurrence of black spots and black stripes during long-term use due to discharge deterioration and lubricant loss, particularly under low temperature and low humidity conditions, which affect the cleaning efficiency and image quality.
Innovation Solution
An image-forming apparatus with an electrophotographic photosensitive member featuring a protective layer formed by polymerizing a composition containing a triphenylamine structure and specific monomers, along with a fatty acid metal salt lubricant, which maintains a moderate affinity between the surface and the lubricant to prevent discharge deterioration and improve cleaning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a radical-polymerizable resin is used in the surface of the photosensitive member to improve abrasion resistance, then mechanical durability is improved, but cleaning difficulty increases leading to black spots and black stripes
Solution Approach 1:
The invention changes the chemical composition parameters of the protective layer by incorporating specific monomers (triphenylamine structure with polymerizable groups, urethane acrylate, and compounds with 6+ polymerizable groups) to achieve optimal balance between abrasion resistance and cleaning ease. The protective layer contains 5-50 mass% of the triphenylamine-containing monomer and 5-50 mass% of the urethane acrylate, with specific molecular weight and functional group ratios that enable both durability and cleanability
Solution Approach 2:
The invention uses a composite protective layer formulation combining multiple components: triphenylamine-containing monomer for charge transport and durability, urethane acrylate for flexibility and adhesion, and additional monomers with 6 or more polymerizable groups for enhanced crosslinking. This composite approach achieves both high abrasion resistance and improved cleaning performance by creating a layered structure with differentiated properties
2Ease of manufacture
If a lubricant is supplied to the surface of the photosensitive member to improve cleaning property, then cleaning ease is improved, but long-term reliability deteriorates due to lubricant loss under low temperature and low humidity conditions
Solution Approach 1:
The protective layer itself provides self-lubrication through its molecular structure. The urethane acrylate and triphenylamine-containing monomer create a surface with inherent lubricating properties that do not require external lubricant application. This self-service mechanism maintains cleaning ease over the entire operational life without lubricant depletion, especially under low temperature and low humidity conditions where external lubricants would fail
Solution Approach 2:
The invention changes the surface energy and friction parameters of the protective layer through specific monomer selection and ratio control. The urethane acrylate component provides low friction coefficients while the triphenylamine structure maintains charge transport efficiency. This parameter optimization enables sustained cleaning performance without external lubricants, preventing the reliability deterioration that occurs with lubricant loss
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 the occurrence of black spots and black stripes by ensuring a stable lubricant film and efficient cleaning, even under challenging conditions, by controlling the content and structure of the protective layer and the fatty acid metal salt's affinity, thereby enhancing image quality and durability.
Implementation Method 1
the protective layer is formed as a cured film by polymerizing a composition containing: a monomer containing a triphenylamine structure and an acryloyloxy group or a methacryloyloxy group
Data Source
AI summary
Provided is an image-forming apparatus including: an electrophotographic photosensitive member including a support, a photosensitive layer, and a protective layer in the stated order; a charging unit; an exposing unit; a developing unit; a transferring unit; and a cleaning unit configured to clean off the toner, which remains on the electrophotographic photosensitive member after the transfer of the toner image from the electrophotographic photosensitive member by the transferring unit, with a cleaning blade, wherein the electrophotographic photosensitive member includes, on a surface thereof, a fatty acid metal salt-supplying unit configured to supply a fatty acid metal salt having 16 or more and 18 or less carbon atoms, and wherein the protective layer has a triphenylamine structure, one of an acryloyloxy group and a methacryloyloxy group, and a specific structure.