PFA Crystal Surface Layer for Stable Electrophotographic Fixing
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Solution Overview
Problem
Existing electrophotographic fixing members experience reduced release property and image quality issues due to uneven surface shapes that decrease friction coefficient, leading to toner slippage and spread during heat fixing, and these shapes can be lost over time due to heat and pressure.
Innovation Solution
An electrophotographic member with a surface layer comprising tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) crystals of varying diameters, structured to maintain a specific arithmetic-mean height distribution, ensuring optimal contact and friction for stable image quality.
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 toner melts and spreads, decreasing image quality
Solution Approach 1:
The patent applies parameter changes by controlling the arithmetic-mean height Sa within a specific range (0.05 μm to 0.20 μm) and regulating the crystal size distribution of PFA to achieve both excellent release property and prevent toner spread. This quantitative parameter control resolves the contradiction between release property and image quality.
Solution Approach 2:
The surface layer is formed as a composite structure consisting of PFA crystals with specific size distribution embedded in a fluororesin matrix. This composite structure provides both the release property from the fluororesin and the friction control from the crystal distribution, resolving the contradiction between release property and image quality.
2Reliability
If mechanical processing methods such as surface transfer or blasting are used to form uneven shape, then release property is improved initially, but the uneven shape is lost due to heat and pressure during heat fixing over time, and release property decreases
Solution Approach 1:
The patent utilizes phase transitions by forming PFA crystals through controlled crystallization from the molten state during heat treatment. The crystals formed through this phase transition are thermally stable and maintain their structure under heat and pressure during fixing, ensuring long-term stability of the uneven surface shape and consistent release property.
Solution Approach 2:
The surface layer structure is designed to be self-maintaining through the inherent thermal stability of PFA crystals. The crystal structure automatically resists deformation under heat and pressure during the fixing process, eliminating the need for external maintenance or reprocessing to maintain release property over time.
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 provides excellent release property and stable high-quality image formation over long-term use by maintaining surface roughness and preventing toner slippage, enhancing both fixing device and image forming apparatus performance.
Implementation Method 1
the outer surface of the electrophotographic member is composed of a surface of the crystals and is roughened by the crystals
Data Source
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.