Conductive Roll Composition for Leak Discharge and Resistance Stability
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Solution Overview
Problem
Conductive rolls in electrophotographic devices face issues with image adverse effects due to leak discharges and environment-dependent resistance, which existing technologies fail to adequately address.
Innovation Solution
A conductive roll design featuring an elastic body layer composed of isoprene rubber and a polar rubber, phase-separated into distinct phases with carbon black, and a surface layer containing crosslinked polyurethane resin, which suppresses leak discharge and resistance variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an ionic conductive agent is used in the elastic body layer, then leak discharge is suppressed, but resistance becomes highly environment-dependent causing image adverse effects
Solution Approach 1:
The patent changes the conductive agent type from ionic to electronic (carbon black), fundamentally altering the conduction mechanism. This parameter change resolves the contradiction by providing both leak discharge suppression and environment-independent resistance stability through electronic conduction in the phase-separated rubber matrix
Solution Approach 2:
The patent uses a composite material system combining isoprene rubber with polar rubber (NBR, ECO, or CR) to create a phase-separated structure. This composite approach allows the non-polar isoprene rubber phase to provide electronic conduction pathways while the polar rubber phase maintains structural integrity, achieving both low leak discharge and stable resistance
2Reliability
If an electronic conductive agent is used in the elastic body layer, then resistance environment dependence is suppressed, but leak discharge cannot be suppressed
Solution Approach 1:
The patent optimizes the resistance value parameter of the elastic body layer to within 1.0×10³ to 1.0×10⁶Ω, which is lower than conventional designs using electronic conductive agents alone. This parameter optimization, combined with the phase-separated structure, suppresses both resistance environment dependence and leak discharge simultaneously
3Strength
If the surface layer uses conventional polyurethane resin, then adhesion is maintained, but glass transition point is too high causing image adverse effects
Solution Approach 1:
The patent changes the polyurethane resin type and optimizes its glass transition point to within -10 to -70°C. This parameter change ensures the surface layer remains flexible at low temperatures while maintaining adhesion to the elastic body layer, preventing image adverse effects
Solution Approach 2:
The patent uses a composite surface layer combining crosslinked polyurethane resin with electronic conductive agents. This composite structure maintains adhesion strength while the low glass transition point of the polyurethane resin prevents brittleness and image defects
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 reduces image adverse effects and minimizes resistance variability across different environmental conditions, ensuring stable performance in electrophotographic devices.
Implementation Method 1
the conductive agent of the elastic body layer is an electronic conductive agent, the environment dependence of the resistance can be suppressed to be small and the image adverse effect caused by the environment dependence can be suppressed, but an image adverse effect caused by the leak discharge may not be suppressed
Implementation Method 2
the surface layer contains an electronic conductive agent and a crosslinked body of at least one polyurethane resin of an ether polyurethane resin and a carbonate polyurethane resin
Data Source
AI summary
An elastic body layer is composed of a conductive rubber composition containing an isoprene rubber, a rubber other than the isoprene rubber, and carbon black. The elastic body layer is phase-separated into a first rubber phase containing the isoprene rubber and a second rubber phase containing the rubber other than the isoprene rubber; in the range of a 5 μm×5 μm square of an arbitrary cross section of the elastic body layer, the area ratio of the first rubber phase is within a range of 10 to 90%. The resistance value of the elastic body layer is within a range of 1.0×103 to 1.0×106Ω. A surface layer contains an electronic conductive agent and a crosslinked body of at least one polyurethane resin of an ether polyurethane resin and a carbonate polyurethane resin, and the glass transition point of the surface layer is within a range of −10 to −70° C.