Resin-Coated Toner Particles With Recess Filling for Fixability
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Solution Overview
Problem
Existing toners with core-shell structures face issues with fixability and heat-resistant preservability due to cracks forming perpendicular to the toner surface, limiting design freedom and increasing production costs, especially when irregularities are present on the toner core particle surface.
Innovation Solution
A toner particle design featuring a toner base particle with recesses and a resin coating, where a coating (B) portion with a thickness of 50 nm or more and 500 nm or less is present on these recesses, providing a laminated structure that enhances fixability and heat-resistant preservability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crack is formed inside the shell layer in a direction substantially perpendicular to the surface of the toner core particle to improve fixability and heat-resistant preservability, then fixability and heat-resistant preservability are improved, but the toner becomes susceptible to bleed-out of the toner core particle and degradation of heat-resistant storability
Solution Approach 1:
The invention introduces protrusions on the toner core particle surface before forming the shell layer. These protrusions serve as pre-positioned structural features that guide the formation of the shell layer, ensuring that the shell layer forms a continuous covering that prevents toner core particle bleed-out while maintaining the necessary cracks for fixability. The protrusions are formed in advance during toner particle production, and the shell layer is subsequently formed around them through coating processes.
Solution Approach 2:
The invention creates local structural variations on the toner core particle surface by forming protrusions at specific locations. These protrusions create localized regions where the shell layer thickness and structure differ from other areas, allowing the shell layer to maintain integrity at protrusion sites (preventing bleed-out) while forming appropriate cracks in recessed areas (enabling fixability). This local differentiation resolves the contradiction between preventing bleed-out and maintaining heat-resistant storability.
2Object-generated harmful factors
If the particle size of resin fine particles is increased to prevent bleed-out, then bleed-out is prevented, but the degree of freedom of toner design is reduced and applicable image forming apparatuses are limited
Solution Approach 1:
The invention changes the critical parameter from resin fine particle size to toner core particle surface protrusion dimensions. Instead of controlling bleed-out through resin particle size (which limits design freedom), the invention uses protrusion height, width, and distribution density as controllable parameters. This parameter transformation allows independent optimization of bleed-out prevention and adaptability to different image forming apparatuses, as protrusion characteristics can be adjusted without being constrained by resin particle size limitations.
Solution Approach 2:
The invention segments the toner core particle surface into multiple protrusion elements distributed across the surface. Rather than relying on a single large resin fine particle for bleed-out prevention, the surface is divided into numerous smaller protrusion features. This segmentation allows for finer control over the shell layer formation and provides flexibility in designing toners for different application requirements, thereby maintaining degree of freedom in toner design.
3Manufacturing precision
If spheroidizing treatment is applied to achieve uniform toner particles, then particle uniformity is improved, but production cost increases
Solution Approach 1:
The invention performs spheroidizing treatment during the toner particle production process itself, rather than as a separate post-processing step. By incorporating shape control into the particle formation process (such as during emulsion polymerization or aggregation), the toner particles achieve uniform spherical shapes with protrusions already integrated into their structure. This preliminary integration eliminates the need for additional spheroidizing equipment and processing steps, thereby reducing production cost while maintaining particle uniformity.
Data Source
AI summary
A toner particle for developing an electrostatically charged image includes a toner base particle and a resin coating covering the toner base particle. The toner base particle includes a recess on a surface of the toner base particle. The recess has a depth of 50 nm to 500 nm. The resin coating includes a coating (A) portion having a thickness of 10 nm or more and less than 50 nm and a coating (B) portion having a thickness of 50 nm or more and 500 nm or less, and the coating (B) portion is present on the recess.