Charge Roller Using Epichlorohydrin Terpolymer for Ozone-Free Charging
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Solution Overview
Problem
Conventional charge rollers used in liquid electro-photograph processes, particularly those made of polyurethane or conventional hydrin materials, face issues with hydrolysis, limited lifespan, and unsatisfactory electrical performance, especially in high-speed industrial applications, leading to increased cost-per-page and reduced print quality.
Innovation Solution
A charge roller comprising a conductive rubber layer made from a terpolymer of epichlorohydrin/ethylene oxide/allyl glycidyl ether, lithium salt, and carbon black, with specific composition and curing conditions to achieve optimal impedance and resistance, ensuring robust electrical performance and compatibility with high-voltage charging modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scorotron devices are used to charge the photo-conductor, then charging function is achieved, but ozone emission is generated
Solution Approach 1:
The patent replaces the scorotron device (corona discharge system) with a mechanical contact charging system using a conductive rubber charge roller. The roller physically contacts the photo-conductor surface to transfer charge, eliminating the need for corona discharge and thereby preventing ozone generation while maintaining effective charging function
Solution Approach 2:
The conductive rubber charge roller serves as an intermediary between the power source and the photo-conductor. It transfers electrical charge through direct contact, acting as a mediator that achieves the charging function without requiring corona discharge, thus avoiding harmful ozone emission
2Reliability
If polyurethane-based charge rollers are used, then charging performance is achieved, but lifespan is limited due to hydrolysis
Solution Approach 1:
The patent uses a composite material formulation for the conductive rubber charge roller that incorporates antioxidants and hydrolysis inhibitors alongside the base rubber compound. This composite structure provides both the necessary charging performance and enhanced resistance to degradation, extending the roller's lifespan by protecting against hydrolytic breakdown
Solution Approach 2:
The patent modifies the chemical composition parameters of the rubber material by adding specific protective additives and adjusting the compound formulation. These parameter changes increase the material's resistance to hydrolysis and oxidation, thereby extending the service life while maintaining charging performance
3Productivity
If conventional charge rollers are used in high-speed industrial applications, then printing speed is achieved, but electrical performance becomes unsatisfactory
Solution Approach 1:
The patent optimizes the electrical parameters of the charge roller by adjusting the conductive rubber compound formulation, including conductivity, surface resistance, and charge transfer characteristics. These parameter optimizations ensure stable and uniform charging performance even at high printing speeds, maintaining reliability while supporting increased productivity
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 provides a charge roller with improved electrical performance, extended lifespan, and uniform charging capabilities, suitable for high-speed liquid electro-photograph processes, with reduced contamination risks and enhanced durability, achieving consistent results up to 1.2 million impressions.
Implementation Method 1
A charge roller comprising a rubber, said rubber being obtainable by curing a composition comprising: a terpolymer of epichlorohydrin/ethylene oxide/allyl glycidyl ether, a lithium salt, and carbon black
Implementation Method 2
Scorotron devices are commonly used to impart electrons on the photo-conductor for the charging purpose. A drawback of scorotron devices resides in the environmentally dangerous ozone emission generated by the corona effect
Data Source
AI summary
The present disclosure discloses a charge roller (1) particularly but not exclusively for charging a photoconductor in a liquid electro-photograph (LEP) image-forming apparatus. The charge roller includes a cured composition of an epichlorohydrin/ethylene oxide/allyl glycidyl ether terpolymer, a lithium salt and carbon black.