Toner with Crystalline Polyester Domains for Fixing and Charge Stability
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Solution Overview
Problem
Toner used in electrophotographic systems faces challenges in maintaining charge stability and releasability in high-temperature, high-humidity environments, with existing solutions exhibiting inadequate performance in terms of charging performance and image quality, including tinge variations and fogging.
Innovation Solution
A toner composition featuring binder resin and crystalline polyester with inorganic fine particles on its surface, where the crystalline polyester is dispersed as domains with specific size and aspect ratio, and the inorganic fine particles have a dielectric constant within a certain range, providing improved charge stability and low-temperature fixability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester is added to improve low-temperature fixability and releasability, then fixing performance is improved, but charging performance deteriorates due to low electrical resistance
Solution Approach 1:
The patent applies local quality by creating distinct domains of crystalline polyester with specific size ranges (0.01-10 μm) and controlling their distribution within the toner particle. This localized structure allows the crystalline polyester to provide low-temperature fixability and good releasability in specific regions while other regions maintain charging performance through appropriate binder resin composition and inorganic fine particle distribution.
Solution Approach 2:
The patent uses composite materials by combining binder resin, crystalline polyester, and inorganic fine particles in a controlled composition. The binder resin provides the matrix structure, crystalline polyester domains provide low-temperature fixability and releasability, while inorganic fine particles compensate for charging performance. This composite approach allows simultaneous achievement of multiple conflicting properties.
2Reliability
If inorganic fine particles with high dielectric constant are added to improve charging performance, then charging stability is improved, but releasability from paper during fixing deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the dielectric constant of inorganic fine particles within a specific range (5-100) and their content (1-20 parts by mass per 100 parts by mass of binder resin). This parameter optimization allows the inorganic fine particles to provide sufficient charging stability while maintaining adequate releasability from paper during fixing, resolving the contradiction between these two properties.
3Temperature
If crystalline polyester domains are increased to improve low-temperature fixability, then fixing performance is improved, but charge stability in high-temperature high-humidity environment deteriorates
Solution Approach 1:
The patent applies local quality by creating distinct domains of crystalline polyester with specific size ranges and controlling their distribution within the toner particle. This localized structure allows the crystalline polyester to provide low-temperature fixability in specific regions while other regions maintain charging performance through appropriate binder resin composition and inorganic fine particle distribution, even in high-temperature high-humidity environments.
Solution Approach 2:
The patent uses inorganic fine particles as an intermediary to mediate between the crystalline polyester domains and the binder resin matrix. These particles help maintain charge stability in harsh environments while allowing the crystalline polyester domains to provide low-temperature fixability, effectively bridging the conflict between these two requirements.
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 toner maintains charge stability and releasability, prevents tinge variations, and reduces fogging in high-temperature, high-humidity conditions, ensuring consistent image quality and performance even after durability testing.
Implementation Method 1
inorganic fine particles having a dielectric constant within a certain range
Implementation Method 2
maintains charge stability
Implementation Method 3
crystalline polyester with specific size and aspect ratio
Implementation Method 4
low-temperature fixability
Data Source
AI summary
A toner including a toner particle that includes a binder resin and a crystalline polyester; and inorganic fine particles on the toner particle surface, wherein a content of the crystalline polyester is 0.5 to 20.0 mass parts per 100 mass parts of the binder resin; in the toner cross section, domains of the crystalline polyester are present in a dispersed state, the percentage for areas of these crystalline polyester domains in the region to a depth of 0.50 μm from a contour of the toner particle is at least 10%, the number average of lengths of a major axis is 120 nm to 1000 nm, and the number average of aspect ratios is not more than 4; a dielectric constant of the inorganic fine particles is 25 to 300 pF/m; and a coverage ratio by the inorganic fine particles on the toner particle surface is 5% to 60%.