Conductive Rubber Composition for Developing Roller
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Solution Overview
Problem
Existing developing rollers in electrophotographic image forming apparatuses face issues with environmental dependence, high cost due to ion conductive rubber, reduced flexibility, and contamination from softening agents or liquid rubber, leading to imaging failures and lower image quality.
Innovation Solution
An electrically conductive rubber composition is developed using ethylene propylene diene rubber, acrylonitrile butadiene rubber, and styrene butadiene rubber, with sulfur and specific crosslinking agents, excluding ion conductive rubber and softening agents, to create a flexible and durable developing roller with improved conductivity and reduced compression set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion conductive rubber is used to produce a developing roller, then the roller has good electrical conductivity, but the conductivity becomes highly environment-dependent and the cost increases
Solution Approach 1:
The patent changes the conductivity mechanism from ionic conduction to electronic conduction by using carbon black as a conductive filler in the rubber composition. This fundamental parameter change eliminates environmental dependence while maintaining electrical conductivity, as electronic conduction is not affected by temperature and humidity variations that impact ionic conduction
Solution Approach 2:
The patent replaces expensive ion conductive rubber with a cost-effective combination of conventional rubber and carbon black filler. This substitution significantly reduces material costs while achieving the desired electrical conductivity through electronic conduction mechanisms
2Ease of manufacture
If electron conductive agent such as carbon black is added to the rubber composition, then the cost is reduced, but the developing roller becomes less flexible and has higher hardness
Solution Approach 1:
The patent uses a composite rubber composition containing multiple rubber types (NBR, SBR, EPDM) combined with carbon black filler. This composite structure allows the material to maintain flexibility from the rubber matrix while achieving electrical conductivity through the carbon black network, resolving the contradiction between cost reduction and flexibility maintenance
Solution Approach 2:
The patent distributes carbon black filler particles locally throughout the rubber matrix at optimized concentrations. This local distribution ensures electrical conductivity is achieved in specific regions without compromising the overall flexibility of the developing roller material
3Ease of manufacture
If the developing roller has higher hardness, then the manufacturing cost is reduced, but the roller degrades toner and reduces imaging durability
Solution Approach 1:
The patent creates a composite material system where the rubber matrix provides flexibility and toner gentleness, while the carbon black filler provides electrical conductivity. This composite structure allows the developing roller to maintain lower hardness for imaging durability while still achieving the required electrical conductivity for proper operation
4Ease of operation
If softening agent or liquid rubber is added to improve flexibility, then the developing roller becomes more flexible, but the compression set increases and contamination occurs
Solution Approach 1:
The patent extracts and eliminates softening agents and liquid rubber components from the formulation. Instead, it achieves the desired flexibility through the intrinsic properties of the selected rubber types (NBR, SBR, EPDM) and their composite structure with carbon black, thereby avoiding contamination issues while maintaining flexibility
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 a more flexible and cost-effective developing roller with improved imaging durability and reduced contamination risks, maintaining image quality across varying environments.
Implementation Method 1
sulfur as a crosslinking agent, and a crosslinking accelerating agent... the crosslinking accelerating agent includes not less than 1.0 part by mass and not greater than 2.0 parts by mass of a thiazole crosslinking accelerating agent
Data Source
AI summary
The present invention provides an electrically conductive rubber composition of an electron conductive type which contains neither an expensive ion conductive rubber having a higher environmental dependence nor a softening agent and a liquid rubber which are liable to increase the compression set of a developing roller or contaminate a photoreceptor body, and is usable for production of a more flexible developing roller. The present invention also provides a developing roller produced by using the rubber composition. The electrically conductive rubber composition contains a rubber component including an EPDM and an NBR and/or an SBR, sulfur, a thiazole crosslinking accelerating agent, tetramethylthiuram monosulfide and tetrabutylthiuram disulfide. The developing roller (1) is formed from the electrically conductive rubber composition.