Ferrite Magnetic Core Material Sulfur Control for Electrophotographic Developers
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Solution Overview
Problem
Current electrophotographic developer carrier materials face challenges in maintaining high image quality and durability due to issues with charge rising-up speed and carrier scattering, particularly with the exposure of ferrite core materials containing sulfur impurities which affect sintering and corrosion, leading to inadequate economic efficiency and image defects.
Innovation Solution
A magnetic core material for electrophotographic developers is developed with controlled sulfur content within a specific range (1 to 45 ppm) to enhance charge rising-up speed and reduce carrier scattering, utilizing a ferrite composition with appropriate particle size, shape, and resin coating to stabilize image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If iron powder carrier is used, then magnetization is high, but agitation and mixing generate fusing of toner components on carrier surface (toner spent)
Solution Approach 1:
The patent replaces the conventional iron powder carrier with a ferrite carrier that has lower magnetization. This substitution accepts reduced magnetic force in exchange for preventing toner spent, effectively treating the carrier as a longer-lasting component that doesn't cause toner degradation. The ferrite carrier maintains sufficient magnetic properties for carrier function while eliminating the harmful high magnetization effect.
Solution Approach 2:
The patent changes the magnetic material parameter from iron powder (high magnetization) to ferrite (low magnetization). This parameter change in the carrier material properties resolves the contradiction by reducing magnetization to a level that prevents toner fusing while maintaining enough magnetic attraction for carrier functionality in the development process.
2Ease of operation
If resin-coated iron powder carrier is used, then carrier function is provided, but resin peels off due to agitation stress and mechanical stress, exposing core material and causing charge leakage
Solution Approach 1:
The patent replaces the iron powder core with ferrite core material. This substitution reduces the need for protective resin coating because ferrite itself has lower conductivity and higher dielectric breakdown voltage. The carrier can maintain its function with minimal or no resin coating, eliminating the peeling problem entirely while preserving charge retention capabilities.
Solution Approach 2:
The patent uses ferrite as the core material which inherently combines magnetic properties with electrical insulation characteristics. This composite approach integrates the magnetic function and charge retention function into a single material system, eliminating the need for a separate resin coating layer that would otherwise peel under stress.
3Ease of manufacture
If sulfur content in ferrite core material is high, then sintering is affected and corrosion occurs, but economic efficiency decreases and image defects occur
Solution Approach 1:
The patent specifies controlling sulfur content in the ferrite core material to within 0.01% by mass or less. This parameter control in the raw material ensures proper sintering process operation, prevents corrosion, and maintains image quality. By setting this specific threshold, the patent resolves the contradiction between ease of manufacture (sintering) and manufacturing precision (image quality).
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 controlled sulfur content in the magnetic core material improves charge rising-up speed, suppresses carrier scattering, and ensures stable image production, extending developer life and maintaining high image quality.
Implementation Method 1
a magnetic core material for electrophotographic developers... utilizing a ferrite composition
Implementation Method 2
controlled sulfur content within a specific range (1 to 45 ppm) to enhance charge rising-up speed and reduce carrier scattering... suppresses carrier scattering
Data Source
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AI summary
To provide a magnetic core material for electrophotographic developer and carrier for electrophotographic developer which are excellent in a rising-up of charge amount, can suppress a carrier scattering, and can stably provide good images; a developer containing the carrier; a method for producing the magnetic core material for electrophotographic developer; a method for producing the carrier for electrophotographic developer; and a method for producing the developer. The magnetic core material for electrophotographic developer, containing a sulfur component in a content of from 1 to 45 ppm in terms of a sulfate ion.