Charge Roller Coating for Liquid Electro-Photography
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Solution Overview
Problem
Existing charge rollers used in liquid electro-photographic processes face issues such as ozone emission from scorotron devices, unsatisfactory surface properties, and short lifespan due to contamination and chemical deterioration, particularly when using hydrin rubber layers in high-speed printing processes.
Innovation Solution
A charge roller with a coating comprising a polyurethane-based rubber obtained from a composition of aromatic diisocyanate, polycarbonate polyester polyol, silica-containing matte agent, fluorinated polyol, and conductive agent, which provides improved surface energy modification, reduced friction, and enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If scorotron devices are used to charge the photo-conductor, then charging function is achieved, but ozone emission is generated which is environmentally dangerous
Solution Approach 1:
The patent replaces the scorotron device (which uses corona discharge/electrical field) with a mechanical charge roller system. The charge roller uses direct mechanical contact and friction between the rubber-coated roller and the photo-conductor surface to transfer charge, eliminating the need for high-voltage corona discharge and thus preventing ozone generation while maintaining effective charging function.
2Reliability
If hydrin rubber layer is used in charge roller, then conductive properties are achieved, but lifespan is reduced due to contamination and chemical deterioration
Solution Approach 1:
The patent uses a composite rubber composition consisting of multiple polymer components (polyurethane, polyacrylonitrile, nitrile rubber) combined in specific ratios. This composite formulation provides both the necessary conductive properties for charging and enhanced resistance to contamination and chemical deterioration, thereby extending the charge roller's operational lifespan compared to pure hydrin rubber.
3Ease of operation
If conventional rubber coating is used on charge roller, then basic charging function is provided, but surface properties are unsatisfactory leading to short lifespan
Solution Approach 1:
The patent systematically adjusts multiple parameters of the rubber coating including composition ratios (polyurethane 20-40%, polyacrylonitrile 30-50%, nitrile rubber 10-30%), molecular weight ranges, and curing conditions to optimize surface properties. These parameter changes result in a coating with appropriate surface energy, friction characteristics, and chemical stability that maintains satisfactory performance and extends service life.
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 charge roller with reduced ozone emission, improved surface properties, extended lifespan, and cost-effectiveness, maintaining high printing quality beyond one million impressions with reduced physical wear and contamination.
Implementation Method 1
improved surface energy modification, reduced friction
Implementation Method 2
conductive agent
Data Source
AI summary
The present disclosure discloses a new charge roller particularly but not exclusively for charging a photoconductive element in a liquid electro-photograph (LEP) image-forming apparatus. The charge roller includes a cured composition of an aromatic diisocyanate, a polycarbonate polyester polyol, a matte agent, a surface energy modifier, and a conductive agent.