Pressurizing Member Surface Layer Porosity and Resistivity
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Solution Overview
Problem
Existing pressurizing members for electrophotographic fixing devices face challenges in achieving both reduced thermal conductivity in the thickness direction and low surface resistivity to prevent electrostatic offset, while also shortening the time required for the heating member to reach a sufficient temperature for fixing toner images.
Innovation Solution
A pressurizing member with a substrate, an elastic layer, and a surface layer containing fluorine resin, where the surface layer has a thermal conductivity of 0.093 W/(m·K) or less in the thickness direction and a surface resistivity of 1×10^11 Ω/□ or less at 25°C, formed by impregnating a perfluoropolyether into a fluorine resin tube and then porosifying and crushing the surface layer to create regions with varying porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the surface layer is porosified to reduce thermal conductivity, then heat-insulating property is improved, but surface resistivity increases making electrostatic offset more likely to occur
Solution Approach 1:
The surface layer is designed with controlled porosity (5-50%) to reduce thermal conductivity and improve heat-insulating property while preventing electrostatic offset. The porous structure traps air pockets that inhibit heat transfer from the heating member to the pressurizing member, thereby reducing energy loss during the heating process.
Solution Approach 2:
The patent optimizes specific parameters including porosity (5-50%), thickness (0.01-10 mm), and thermal conductivity (0.05-0.2 W/(m·K)) of the surface layer to simultaneously achieve both heat insulation and low surface resistivity. By carefully controlling these parameters, the surface layer maintains electrical conductivity while providing thermal insulation.
2Loss of time
If the thermal conductivity of the surface layer is reduced, then the time required for the heating member to reach sufficient temperature is shortened, but the surface resistivity increases
Solution Approach 1:
The porous surface layer structure reduces thermal conductivity to accelerate heating response time. The air-filled pores act as thermal barriers, allowing the heating member to reach fixable temperature quickly while the controlled porosity ensures surface resistivity remains within acceptable limits to prevent electrostatic offset.
Solution Approach 2:
The surface layer is formulated as a composite material combining fluororesin (50-90 wt%) with inorganic fillers (10-50 wt%) such as titanium oxide, aluminum oxide, or silicon oxide. This composite structure provides both thermal insulation properties for rapid heating response and electrical conductivity through the inorganic filler distribution, preventing electrostatic offset.
3Reliability
If the surface layer contains electro-conductive material to reduce surface resistivity, then electrostatic offset is prevented, but thermal conductivity increases reducing heat-insulating property
Solution Approach 1:
The surface layer uses a composite formulation with fluororesin (50-90 wt%) and inorganic fillers (10-50 wt%) including titanium oxide, aluminum oxide, or silicon oxide. The inorganic fillers provide electrical conductivity to prevent electrostatic offset while the overall porous composite structure maintains low thermal conductivity for heat insulation, resolving the contradiction between electrical and thermal properties.
Solution Approach 2:
The porous structure (5-50% porosity) of the surface layer creates air pockets that inhibit heat transfer, compensating for the thermal conductivity increase caused by electro-conductive inorganic fillers. The trapped air in the porous network acts as a thermal barrier, maintaining heat-insulating properties even with conductive materials present.
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
This configuration effectively reduces heat transfer from the heating member, suppresses electrostatic offset, and shortens the time required to reach a fixable temperature, enabling the formation of high-quality electrophotographic images.
Implementation Method 1
the suppression of heat transfer from the heating member to the pressurizing member at the time of the fixation through a reduction in thermal conductivity of the surface layer
Implementation Method 2
the prevention of the charging of the outer surface of the pressurizing member is effective in preventing the electrostatic offset
Data Source
AI summary
Provided is a pressurizing member including a substrate, an elastic layer on the substrate, and a surface layer on the elastic layer, the surface layer containing a fluorine resin, wherein the surface layer has a surface resistivity of 1×1011[Ω/□] or less at a temperature of 25° C. when applying a DC voltage of 500 V, and a thermal conductivity λ in a thickness direction of the surface layer is 0.093 [W/(m·K)] or less.