Conductive Roll Rubber Composition Hardness and Resistivity
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Solution Overview
Problem
Conductive rolls used in printer and image forming devices require a rubber composition that balances low hardness, low volume resistivity, and excellent compression set resistance, which existing materials fail to achieve simultaneously.
Innovation Solution
A cross-linkable rubber composition comprising polyether rubber, solid nitrile rubber, liquid nitrile rubber, a sulfur-containing cross-linking agent, a disulfide-based cross-linking accelerator, and conductive carbon black with specific particle size and surface area, which are cross-linked to produce a rubber with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional rubber compositions are used to reduce hardness, then the rubber layer must be made foamed rubber, but this results in poor compression set resistance and insufficient electrical conductivity control
Solution Approach 1:
The invention changes the chemical composition parameters by introducing a specific rubber blend (nitrile rubber 30-70 parts, neoprene rubber 10-40 parts, polyether rubber 5-30 parts) and controlled crosslinking system (sulfur 0.5-5 parts, crosslinking accelerator 1-10 parts) to achieve low hardness without foaming, thereby maintaining compression set resistance
Solution Approach 2:
The invention uses a composite rubber material system combining multiple rubber types (nitrile rubber, neoprene rubber, polyether rubber) with conductive carbon black (5-20 parts) and crosslinking agents to create a multi-phase composite that simultaneously achieves low hardness, good compression set resistance, and controllable electrical conductivity without requiring foamed structure
2Reliability
If crosslinking is performed to improve compression set resistance, then the rubber composition becomes more rigid, but this increases hardness and volume resistivity
Solution Approach 1:
The invention controls the crosslinking degree by limiting sulfur content to 0.5-5 parts and crosslinking accelerator to 1-10 parts per 100 parts of rubber, and by using a two-stage crosslinking process (first at 50-100°C for 5-30 minutes, then at 100-200°C for 5-60 minutes) to achieve adequate compression set resistance while maintaining hardness below 80 Shore A
Solution Approach 2:
The invention applies partial crosslinking rather than complete crosslinking, using moderate amounts of crosslinking agents and controlled crosslinking time/temperature, which provides sufficient compression set resistance (less than 50% after 22 hours at 70°C) while avoiding excessive rigidity and hardness increase
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 exhibits low hardness, low volume resistivity, and superior compression set resistance, making it suitable for conductive rolls in printers and image forming devices.
Implementation Method 1
a sulfur-containing cross-linking agent, disulfide-based cross-linking accelerator
Implementation Method 2
conductive carbon black with an average primary particle size of 50 nm or less and with a BET specific surface area of 600 m2
Data Source
AI summary
A cross-linkable rubber composition for conductive roll use which contains a polyether rubber, solid nitrile rubber, liquid nitrile rubber, sulfur-containing cross-linking agent, disulfide-based cross-linking accelerator, and conductive carbon black with an average primary particle size of 50 nm or less and with a BET specific surface area of 600 m2/g or more is provided. According to the present invention, it is possible to provide a cross-linkable rubber composition for conductive roll use which can give cross-linked rubber which is low in hardness, is low in volume resistivity value, and excellent in pressure-resistant compression set.