Developing Member Surface Layer Toner Fusion Prevention
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Solution Overview
Problem
Electrophotographic image forming apparatuses experience degradation in image quality due to toner fusion on the developing member's surface, leading to variations in charge imparting and toner conveying performance, especially under low-temperature and low-humidity conditions, causing inconsistent image output over time.
Innovation Solution
A developing member with a surface layer containing a polyurethane resin as a binder and dispersed polyurethane resin particles, featuring specific structural formulas that prevent toner fusion and resin particle fallout, ensuring stable performance even after long-term use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the surface layer of the developing member is softened to suppress toner fusion, then toner fusion is suppressed, but resin particles fall off and the surface shape changes over time, causing variation in toner conveying performance
Solution Approach 1:
The invention changes the chemical composition parameters of the binder resin by incorporating specific compounds (polyester polyol with glass transition temperature of -50°C or lower, and polyether polyol with glycidyl group content of 5-50 mmol/g) to achieve both softness for toner fusion suppression and structural stability for preventing resin particle fall-off
Solution Approach 2:
The invention uses a composite binder resin system combining polyester polyol and polyether polyol with specific functional groups, creating a material that exhibits both the softness needed to prevent toner fusion and the structural integrity needed to maintain surface shape stability over time
2Manufacturing precision
If fine resin particles are contained in the surface layer to form convex portions for uniform charge imparting and toner conveying, then charge imparting uniformity is improved, but the resin particles are liable to fall off under low-temperature and low-humidity conditions, degrading image quality
Solution Approach 1:
The invention adjusts the glass transition temperature parameter of the polyester polyol component to -50°C or lower, which fundamentally changes the thermal properties of the surface layer to maintain resin particle stability under low-temperature conditions while preserving the convex portion structure for uniform charge imparting
3Productivity
If the developing member is used under low-temperature and low-humidity conditions for long periods, then productivity is maintained, but toner fuses onto the surface causing degradation in charge imparting and toner conveying performance
Solution Approach 1:
The invention incorporates the specific binder resin composition with low glass transition temperature and glycidyl groups into the surface layer in advance, creating a protective effect that prevents toner fusion before it occurs during extended operation under low-temperature conditions
Solution Approach 2:
The invention creates a self-healing surface layer through the specific resin composition that can maintain its functional properties over extended periods without requiring replacement, effectively treating the developing member as a long-life component that maintains performance consistency
Data Source
AI summary
The present invention provides a developing member onto which a toner or the like is hard to fuse and with which toner conveying performance is unlikely to vary even through long-term usage. The developing member includes a substrate and a surface layer, the surface layer contains a polyurethane resin working as a binder resin and polyurethane resin particles dispersed in the binder resin, and the polyurethane resin working as the binder resin has, between two adjacent urethane bonds, a structure represented by a structural formula (1) and one or both of structures represented by structural formulas (2) and (3), and further has, between two adjacent urethane bonds, a structure represented by a structural formula (4).