Conductive Roller Voids and Surface Roughness Control
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Solution Overview
Problem
Roller members with conductive elastic layers in electrophotographic processes often suffer from surface voids caused by water evaporation during vulcanization, leading to faulty images due to air bubbles, which existing methods like using dehydrating agents fail to adequately address, especially with ion-conductive rubbers that absorb water.
Innovation Solution
A roller member with a conductive elastic layer having controlled surface roughness and voids, where the voids are shaped and aligned to minimize their impact on surface properties, achieved by pressing a form with specific surface roughness against the unvulcanized rubber composition during vulcanization, allowing for good surface properties despite the presence of voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water is incorporated in the rubber or rubber composition, then the rubber becomes more flexible and easier to process, but air bubbles (voids) are produced in the elastic layer during vulcanization due to water evaporation
Solution Approach 1:
The patent applies preliminary action by pre-heating the mandrel before extruding the rubber composition. This pre-heating causes water in the rubber composition to evaporate during extrusion rather than during vulcanization, preventing void formation in the elastic layer while maintaining the flexibility benefits of water-containing rubber compositions.
2Manufacturing precision
If dehydrating agents are added to remove water content, then water-related voids are reduced, but the elastic layer becomes harder and loses flexibility
Solution Approach 1:
The patent extracts water from the rubber composition through evaporation during extrusion (by pre-heating the mandrel) rather than using dehydrating agents. This removes the harmful water that would cause voids during vulcanization while preserving the flexibility of the rubber composition, as no dehydrating agents are added to the rubber formulation.
3Reliability
If ion-conductive rubber with polar groups is used, then conductivity is improved, but water absorption increases leading to more voids
Solution Approach 1:
The patent applies preliminary action by pre-heating the mandrel to evaporate water during extrusion. This is particularly effective for ion-conductive rubbers with polar groups that tend to absorb water, as it removes the absorbed water before vulcanization, preventing void formation while maintaining the high conductivity properties of the polar rubber composition.
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 results in roller members with improved surface roughness and reduced coating defects, enabling stable and uniform image formation even when voids are present, without the need for additional polishing or surface treatments.
Implementation Method 1
air bubbles (hereinafter 'voids') may be produced in the elastic layer as a result of the evaporation of water incorporated in the rubber or rubber composition, caused by the heat at the time of vulcanization
Data Source
AI summary
In a roller member having at least a mandrel and a conductive elastic layer provided on the peripheral surface of the mandrel, the roller member has a surface roughness Rz jis 94 of from 0.5 μm to 10 μm, and the roller member contains voids in the vicinity of its surface. Substantially all of the voids have an average internal diameter of from 10 μm to 400 μm and an aspect ratio of from 1.3 or more to 10.0 or less, and having an angle of from 0° or more to 45° or less as an acute angle between an axis that takes the maximum internal diameter of each of the voids and a tangent to a concentric circle of the roller member at the center of each of the voids.