Ferrite Core-Shell Particles for Stable Electrophotographic Charging
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Solution Overview
Problem
Ferrite carrier particles used in electrophotographic developers face challenges with high apparent density, difficulty in controlling charging properties and electric resistivity, and issues with resin coating leading to instability and image quality fluctuations.
Innovation Solution
Ferrite particles with a core-shell structure containing a Ti oxide outer shell, where the shell thickness is between 0.5 to 10 μm, and the internal part has a lower density, allowing for controlled properties and reduced resin usage, enhancing charging stability and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional ferrite carrier particles are used, then high apparent density is achieved, but difficulty in controlling charging properties and electric resistivity occurs
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the outer shell has different composition and properties than the inner core. The shell contains SrO (0.3-4.0 wt%) and TiO2 (0.5-5.0 wt%) which provide controlled charging properties and electric resistivity, while the core provides the ferrite base structure. This localized differentiation allows independent optimization of density and charging characteristics.
Solution Approach 2:
The patent uses composite materials by combining ferrite base material with SrO and TiO2 additives to create a multi-component system. This composite structure enables simultaneous achievement of desired apparent density, charging properties, and electric resistivity that cannot be obtained with single-component ferrite particles alone.
2Reliability
If resin coated ferrite carriers are used, then charging properties are improved, but resin peeling and image quality fluctuations occur due to internal stress
Solution Approach 1:
The patent applies beforehand cushioning by incorporating SrO and TiO2 into the shell structure prior to resin coating. This pre-formed stable shell acts as a buffer that absorbs internal stresses during operation, preventing resin peeling and maintaining coating integrity over extended usage periods.
Solution Approach 2:
The patent changes material parameters by adjusting SrO content (0.3-4.0 wt%) and TiO2 content (0.5-5.0 wt%) to optimize the shell's mechanical and electrical properties. These parameter adjustments create a shell with appropriate flexibility and adhesion characteristics that accommodate internal stresses without failing.
3Use of energy by moving object
If low-temperature fixing is implemented, then energy saving is achieved, but toner sticking to carrier surface increases due to internal stress
Solution Approach 1:
The patent changes the thermal and surface parameters of the carrier by incorporating TiO2 (0.5-5.0 wt%) into the shell structure. This modification adjusts the surface energy and thermal expansion characteristics, reducing toner adhesion at low fixing temperatures and preventing harmful sticking even when energy-saving low-temperature fixing is employed.
4Reliability
If carrier amount is increased, then image quality stability is improved, but running cost increases
Solution Approach 1:
The patent changes the compositional parameters of the ferrite particles by optimizing SrO (0.3-4.0 wt%) and TiO2 (0.5-5.0 wt%) content to enhance charging stability and image quality consistency. This allows achieving reliable image quality with reduced carrier amounts by improving the per-particle performance rather than increasing total quantity.
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 ferrite particles achieve low apparent density and controlled properties, ensuring stable image formation and extended usage without resin peeling or charging fluctuations, making them suitable for high-definition and high-speed printing applications.
Implementation Method 1
ferrite carrier particles mixed and stirred with toner particles achieve functions for triboelectrically charging and carrying toner particles
Implementation Method 2
a ferrite carrier core material composed of porous ferrite particles
Data Source
AI summary
An object of the present invention is to provide a ferrite particle having a low apparent density, filling a specified volume with a low weight with various properties maintained in a controllable state, a ferrite carrier core material composed of the ferrite particle, and a ferrite carrier using the ferrite core material and an electrophotographic developer. To achieve the object, the ferrite particle having the outer shell structure containing the Ti oxide for the ferrite carrier core material, and the ferrite carrier using the ferrite particle as the ferrite carrier core material and the electrophotographic developer are employed.