Resin-Coated Ferrite Carrier Shape Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrophotographic ferrite carriers with small particle sizes struggle to maintain a spherical shape and uniform surface, leading to increased carrier scattering and variations in charge quantities and resistance over time, which affects image quality and durability in continuous printing.
Innovation Solution
A resin-coated ferrite carrier with a specific range of apparent density, average particle size, and BET specific surface area, combined with controlled slurry particle sizes and baking temperatures, ensures a spherical shape and sharp particle size distribution, reducing carrier scattering and maintaining consistent charge and resistance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the particle size of ferrite carrier is reduced to achieve high-quality images, then the specific surface area increases and toner holding capacity improves, but the spherical shape cannot be sustained and particle fusion occurs during high-temperature heating
Solution Approach 1:
The patent applies preliminary action by performing a first firing at a lower temperature (900-1100°C) before the second high-temperature firing (1100-1450°C). This preliminary firing pre-sinteres the ferrite particles, creating a stable structure that prevents fusion during the subsequent high-temperature firing, while still achieving the desired small particle size and high specific surface area
Solution Approach 2:
The patent changes the temperature parameter by dividing the firing process into two distinct stages with different temperature ranges. The first firing uses 900-1100°C and the second firing uses 1100-1450°C, with the temperature difference controlled at 280°C or less. This parameter change allows achieving small particle size without particle fusion
2Length of moving object
If the ferrite particles are ground strongly to achieve small particle size, then the particle size reduces, but the particles are crushed and irregular particles are generated causing beads carry over
Solution Approach 1:
The patent applies preliminary action by performing preliminary firing before the final grinding step. This preliminary sintering strengthens the ferrite particles, making them more resistant to crushing during subsequent grinding operations, thereby reducing the generation of irregular particles that cause beads carry over
Solution Approach 2:
The patent skips the intermediate classification step that would separate irregular particles, instead relying on the preliminary firing to prevent irregular particle formation in the first place. The controlled firing process ensures particles maintain their spherical shape throughout grinding
3Reliability
If the resin coating is applied to enhance abrasion resistance and durability, then the carrier durability improves, but coating unevenness is generated when the ferrite particle shape is impaired
Solution Approach 1:
The patent applies preliminary action by performing preliminary firing before resin coating to establish a stable, spherical particle shape. This pre-formed stable structure provides a uniform surface that ensures even resin coating distribution, preventing coating unevenness while maintaining the durability benefits of resin coating
4Quantity of substance
If the ferrite carrier provides small particle size with sharp distribution, then image quality improves, but carrier scattering increases and charge quantity variation occurs over time
Solution Approach 1:
The patent applies preliminary action by performing preliminary firing to stabilize the ferrite particle structure before final size reduction and resin coating. This preliminary stabilization prevents particle aggregation and maintains uniform charge distribution, reducing carrier scattering and charge quantity variation over time while preserving sharp particle size distribution
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 ferrite carrier with low beads carry over and stable performance over time, enhancing image quality and durability in continuous printing while being economically producible at an industrial scale.
Implementation Method 1
the ferrite after the ferritization reaction has high hardness
Implementation Method 2
various resins are coated on the surface of the carrier core (ferrite particles)
Data Source
Figure 1
AI summary
There are adopted an electrophotographic resin-coated ferrite carrier having a carrier core coated with a resin, wherein a product of an apparent density ρ (g/cm3), average particle size d (µm) and BET specific surface area S (m2/g) of the carrier core satisfies the following condition, a method for producing the same, and an electrophotographic developer. 4.5≤ρ×d×s≤8.520≤d≤45