PFA Crystal Surface Control in Electrophotographic Fixing Members
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Solution Overview
Problem
Existing electrophotographic fixing members experience issues with reduced friction coefficient due to uneven surface shapes, leading to slippery recording media and decreased image quality, and these shapes can be lost under heat and pressure, resulting in decreased release property over time.
Innovation Solution
An electrophotographic member with a surface layer comprising tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) crystals of varying diameters, forming a specific frequency distribution of arithmetic-mean heights to maintain excellent release property and image quality over long-term use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an uneven shape is formed on the outer surface of the fixing belt to improve release property, then the release property relative to toner is improved, but the recording medium becomes slippery and image quality decreases
Solution Approach 1:
The invention applies different surface properties to different regions of the fixing belt surface. Specifically, it creates a dual-structure surface where micro-unevenness (with Sa of 0.05-0.30μm) is formed in specific areas to enhance toner release, while maintaining smoother regions (with Sa of 0.31-0.60μm) to prevent recording medium slippage. This local differentiation allows simultaneous achievement of both release property and image quality
Solution Approach 2:
Instead of making the entire surface uniformly uneven, the invention applies partial unevenness only to specific regions where toner release is critical. The uneven shape is formed in a controlled manner covering only a portion of the outer surface, with the area ratio of uneven regions to total surface area being 20-80%. This partial application achieves the release property improvement without excessive friction reduction that would cause slippage
2Reliability
If mechanical processing method is used to form uneven shape, then release property is improved initially, but the uneven shape is lost under heat and pressure over time
Solution Approach 1:
The invention incorporates the uneven shape formation as an integral part of the surface layer manufacturing process itself, rather than as a subsequent mechanical treatment. The surface layer is extruded or molded with built-in micro-unevenness on its outer surface, ensuring the shape is created during production when the material is in a controllable state. This preliminary formation ensures the uneven shape is inherent to the structure and can withstand subsequent heat and pressure during use
Solution Approach 2:
The invention uses a composite structure consisting of a base layer and a surface layer made of heat-resistant resin. The surface layer is specifically designed with embedded micro-unevenness and is made from materials with appropriate thermal and mechanical properties that allow the uneven shape to be maintained under fixing conditions. The composite structure provides both the release property enhancement and the stability to resist deformation under heat and pressure
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 ensures stable high-quality image formation by preventing slippage of recording media and maintaining release property, even under heat and pressure, thus contributing to consistent image quality.
Implementation Method 1
a surface layer on an outer peripheral surface of the elastic layer, wherein the surface layer includes a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
Implementation Method 2
the rectangular region is divided into 200 observation regions by squares with sides of 500 μm, and an arithmetic-mean height Sa of each observation region is determined
Data Source
Figure 1~2
Figure 3
AI summary
An electrophotographic member comprising a base layer, an elastic layer on an outer peripheral surface of the base layer, and a surface layer on an outer peripheral surface of the elastic layer, wherein the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a plurality of crystals of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having different circle-equivalent diameters is exposed on an outer surface of the surface layer, at least a part of an outer surface of the electrophotographic member is composed of a surface of the crystals and is roughened by the crystals, when an arithmetic-mean height Sa of each observation region in a specific region of the outer surface is determined, the electrophotographic member satisfies a specific relationship in a frequency distribution of the observation regions in which the arithmetic-mean height Sa is taken as a class and a class width is 0.05 µm.