Conductive Rubber Transfer Roller for Stable Image Quality
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Solution Overview
Problem
Transfer rollers used in electrophotographic image forming apparatuses, made from styrene butadiene rubber, suffer from significant variations in roller resistance due to environmental factors like temperature and humidity, affecting image density and quality.
Innovation Solution
An electrically conductive rubber composition is developed, comprising ethylene propylene diene rubber (EPDM), epichlorohydrin rubber, and styrene butadiene rubber (SBR) or butadiene rubber (BR), with a specific proportion of foaming agents and assisting agents for in-can vulcanization, which reduces foam cell diameters and enhances flexibility, ozone resistance, and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If styrene butadiene rubber (SBR) is used as the main rubber for the transfer roller, then production costs are reduced, but roller resistance varies significantly with environmental factors like temperature and humidity
Solution Approach 1:
The patent uses a composite rubber composition comprising SBR (for cost reduction), EPDM (for ozone resistance and flexibility), and a conductive agent (for electrical conductivity). This composite structure allows each component to contribute its advantageous properties while compensating for the weaknesses of individual materials, specifically stabilizing roller resistance against environmental variations.
Solution Approach 2:
The patent optimizes the proportion of each rubber component and conductive agent in the composition to achieve stable roller resistance. By carefully controlling the ratios of SBR, EPDM, and conductive agents, the composition maintains consistent electrical properties across different temperature and humidity conditions while keeping production costs low.
2Quantity of substance
If the transfer roller is made from a foamed structure, then material costs and weight are reduced, but the smoothness of the outer peripheral surface may be compromised
Solution Approach 1:
The patent employs a foamed rubber structure with controlled cell sizes and distribution. The foam cells are uniformly distributed and sized to minimize surface irregularities, allowing the transfer roller to maintain adequate surface smoothness for image quality while significantly reducing material consumption and weight compared to solid rubber construction.
3Productivity
If the decomposition temperature of the foaming agent is reduced for faster foaming, then production time is shortened, but the control over foam cell size and distribution becomes more difficult
Solution Approach 1:
The patent introduces a foaming assistant substance that acts as an intermediary between the foaming agent and the rubber matrix. This assistant substance facilitates controlled decomposition of the foaming agent at lower temperatures, enabling rapid foaming while maintaining uniform foam cell size and distribution through moderated gas release and bubble nucleation control.
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 transfer roller with reduced environment-dependent variations in roller resistance, lower production costs, and improved image quality, maintaining flexibility and ozone resistance while ensuring proper ion conductivity.
Implementation Method 1
a foaming agent thermally decomposable to generate gas
Implementation Method 2
foaming and crosslinking the rubber composition of the tubular body in a vulcanization can by applying pressure and heat to the tubular body with pressurized steam
Data Source
AI summary
An electrically conductive rubber composition is provided, which is usable for production of a transfer roller of a highly flexible foam satisfying requirements for cost reduction and weight reduction and having smaller foam cell diameters and, hence, ensuring higher-quality image formation with smaller environment-dependent variations in roller resistance. A transfer roller produced from the electrically conductive rubber composition, a production method for the transfer roller, and an image forming apparatus including the transfer roller are also provided. The electrically conductive rubber composition contains a rubber component including SBR and/or BR, EPDM and epichlorohydrin rubber, a crosslinking component, and 4 to 6 parts by mass of a foaming agent and 1.5 to 2.7 parts by mass of a foaming assisting agent based on 100 parts by mass of the rubber component. The transfer roller (1) is produced by extruding the electrically conductive rubber composition into a tubular body and performing an in-can vulcanization process on the tubular body. The image forming apparatus incorporates the transfer roller.