Composite Core Toner with Protruding Magnetic Particles
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Solution Overview
Problem
The existing electrostatic latent image developing toners face issues with adhesiveness and chargeability, leading to carrier contamination and reduced image quality due to excessive releasing agent precipitation in high temperature and humidity environments, and have limited fixing operation windows due to reduced elasticity and high glass transition points of resin in the shell layers.
Innovation Solution
The toner particles are designed with a composite core comprising a toner core, organic particles, and polyhedral magnetic particles, where the releasing agent is present in the organic particles rather than the toner core, and the magnetic particles protrude from the shell layer to improve releasability and chargeability, while the organic particles at the interface between the toner core and shell layer enhance low-temperature fixability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the releasing agent is contained in the toner core, then the toner has good releasability, but the releasing agent precipitates excessively in high temperature and humidity environments, causing carrier contamination and reduced image quality
Solution Approach 1:
The patent divides the toner structure into distinct layers: a toner core containing binder resin and colorant, and a shell layer containing the releasing agent. This segmentation isolates the releasing agent to the shell layer, preventing excessive precipitation while maintaining releasability at the toner surface.
Solution Approach 2:
The releasing agent is localized specifically in the shell layer rather than being distributed throughout the entire toner core. This local concentration ensures releasability where needed (at the surface) while preventing widespread precipitation and carrier contamination.
2Reliability
If the shell layer resin has high glass transition point, then the toner has good heat-resistant preservability, but the fixing operation window is limited and low-temperature fixability is reduced
Solution Approach 1:
The patent adjusts the glass transition point of the shell layer resin to a specific range (−50°C to 150°C) that balances heat-resistant preservability with adequate elasticity for fixing. This parameter optimization expands the fixing operation window while maintaining necessary thermal stability.
Solution Approach 2:
The shell layer uses a composite resin system combining polymers with different glass transition characteristics. This composite approach provides both heat resistance and sufficient elasticity, enabling broader fixing temperature ranges and improved low-temperature fixability.
3Stability of the object's composition
If magnetic particles are completely covered by the shell layer, then the toner has good structural integrity, but the chargeability and releasability are insufficient
Solution Approach 1:
The shell layer is designed with localized magnetic particle protrusions rather than complete coverage. This creates regions of enhanced chargeability and releasability at the protruding magnetic particle surfaces while maintaining structural integrity in the covered regions.
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
This design improves the toner's releasability, chargeability, and fixing operation window, preventing precipitation of the releasing agent and ensuring sufficient elasticity and low-temperature fixability, thereby enhancing image quality and reducing carrier contamination.
Implementation Method 1
The magnetic particles include magnetic particles adhering to the surface of the toner core and magnetic particles adhering to surfaces of the organic particles
Implementation Method 2
a carrier configured to positively charge the toner by friction therewith
Implementation Method 3
The organic particles each contain a releasing agent and adhere to a surface of the toner core
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
An electrostatic latent image developing toner includes toner particles (10) each including a toner mother particle (10a) and an external additive (15). The toner mother particle includes a composite core and a shell layer (12). The composite core is a composite of a toner core (11), organic particles (13), and polyhedral magnetic particles (14). The organic particles each contain a releasing agent and adhere to a surface of the toner core. The magnetic particles include magnetic particles on the toner core and magnetic particles on the organic particles. An amount of the magnetic particles is 0.5 parts by mass to 2.0 parts by mass relative to 100 parts by mass of the toner cores. In a cross-sectional image of each toner particle, an area of protruding portions of the magnetic particles, which protrude from the shell layer, accounts for 10% to 75% of an overall area of the magnetic particles.