Black Magnetic Iron Oxide Particles with Core-Shell Sulfur Distribution
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Solution Overview
Problem
Conventional black magnetic iron oxide particles fail to exhibit sufficient blackness when incorporated into thin coating films due to inadequate sulfur distribution and content, leading to suboptimal performance in magnetic toners.
Innovation Solution
Developing black magnetic iron oxide particles with a polyhedral shape, specific sulfur and carbon content, and surface modifications with Al and Si, ensuring a sulfur distribution of less than 40% and a carbon content of 0.02-0.50% by weight, which are then used to form a coating film with optimal blackness characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional black magnetic iron oxide particles are used, then the coating film can be formed, but the blackness is insufficient when incorporated into thin coating films
Solution Approach 1:
The patent applies local quality by creating a non-uniform sulfur distribution within the magnetite particles. Specifically, sulfur is concentrated in the core region while being suppressed at the surface, forming a core-shell like structure. This local differentiation of sulfur concentration optimizes the optical properties for enhanced blackness in thin coating films while maintaining the magnetic properties of the bulk material.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the sulfur content and its spatial distribution within the magnetite particles. By adjusting the sulfur concentration parameter (0.1-5.0 wt%) and its dissolution percentage (30-70% of total sulfur in the core region), the optical absorption characteristics are optimized to achieve superior blackness in thin film applications without compromising particle stability.
2Illumination intensity
If sulfur content is increased to improve blackness, then blackness enhancement is achieved, but oxidation resistance may be compromised
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatial separation of sulfur concentration. The core region contains higher sulfur content (0.3-5.0 wt%) to provide strong optical absorption and blackness, while the surface region maintains lower sulfur content (0.03-0.5 wt%) to preserve oxidation resistance. This gradient distribution allows simultaneous optimization of both optical and chemical stability properties.
Solution Approach 2:
The patent uses the magnetite crystal structure as an intermediary medium that hosts sulfur atoms in specific lattice positions. By controlling sulfur substitution of oxygen atoms in the magnetite structure and creating a core-shell sulfur distribution, the system mediates between the competing requirements of high sulfur content for blackness and low surface sulfur for oxidation resistance.
Data Source
AI summary
The present invention relates to a black magnetic iron oxide particles each having a polyhedral shape wherein when a percentage of dissolution of iron element based on a total amount of iron element contained in the black magnetic iron oxide particles is 50%, a percentage of dissolution of sulfur element based on a total amount of sulfur element contained in the black magnetic iron oxide particles is less than 40%.