Conductive Rubber Composition for Photoconductor Roll Applications
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Solution Overview
Problem
Conductive rubber rolls used in electronic photo devices face challenges in achieving low volume resistivity and hardness while preventing contamination of photoconductors, as existing solutions either result in high electrical resistance or require large amounts of carbon black, making it difficult to balance conductivity and hardness.
Innovation Solution
A rubber composition is produced by dissolving polyether rubber in a solvent and mixing it with a liquid ethylenically unsaturated nitrile-conjugated diene copolymer rubber, achieving a cross-linked rubber with low volume resistivity and hardness, and minimizing contamination when used as a conductive member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductivity imparting material such as carbon black is added to rubber to improve conductivity, then volume resistivity is reduced, but hardness becomes higher
Solution Approach 1:
The invention changes the physical state parameter of the rubber from solid to liquid by using a liquid rubber composition. This parameter change allows the rubber to better conform to the photoconductor surface while maintaining low hardness, as the liquid state inherently provides lower resistance to deformation compared to solid rubber with the same composition.
Solution Approach 2:
The invention uses a composite material system combining liquid rubber with specific conductivity imparting materials (carbon black or metal powder) and silane coupling agents. This composite approach allows optimization of both conductivity and hardness independently, as each component contributes different properties that can be tuned separately through formulation.
2Strength
If plasticizer or softener is blended into conductive rubber to reduce hardness, then hardness drops, but the plasticizer or softener bleeds out and contaminates the photoconductor
Solution Approach 1:
The invention employs silane coupling agents that form cross-linked networks within the rubber matrix, creating a molecular structure that permanently traps conductivity imparting materials and prevents their migration. This chemical bonding approach replaces temporary physical mixing, eliminating the bleedout problem entirely rather than just reducing it.
Solution Approach 2:
The invention creates local quality differences within the rubber composition by using silane coupling agents that concentrate at the interface between conductivity imparting materials and the rubber matrix. This localized chemical modification prevents migration at critical interfaces while maintaining overall material flexibility and low hardness.
3Strength
If solid rubber and liquid rubber are blended to reduce hardness, then hardness drops, but electrical resistance value increases making it insufficient for high-speed devices
Solution Approach 1:
The invention changes the dispersion state parameter of conductivity imparting materials from aggregated (in solid rubber blends) to molecularly dispersed (in liquid rubber with silane coupling). This parameter change dramatically improves electrical conductivity by creating more continuous conductive pathways throughout the material while the liquid state maintains low hardness.
Solution Approach 2:
The silane coupling agent acts as an intermediary that bridges the conductivity imparting materials and the liquid rubber matrix. This intermediary creates strong chemical bonds that form a percolating network for electrical conduction while the liquid rubber provides the flexible, low-hardness matrix, solving both conductivity and hardness requirements simultaneously.
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 resulting cross-linked rubber effectively reduces photoconductor contamination and maintains low hardness, enabling efficient conductivity suitable for electronic photo devices.
Implementation Method 1
a polyether rubber which is dissolved in a solvent at 0.1 to 30 wt % of concentration
Implementation Method 2
gives a cross-linked rubber which has a low volume resistivity value, which is low in hardness
Data Source
AI summary
To provide a method for producing a rubber composition which gives a cross-linked rubber which has a low volume resistivity value, which is low in hardness, and which is kept down in contamination of the photoconductor when used as a conductive member. A production method of a rubber composition comprising a step of mixing a polyether rubber which is dissolved in a solvent at 0.1 to 30 wt % of concentration and a liquid ethylenically unsaturated nitrile-conjugated diene copolymer rubber in a solution is provided.