Toner Surface Structure for Low-Temperature Fixability
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Solution Overview
Problem
Existing electrostatic image developing toners face challenges with low-temperature fixability due to insufficient release agent bleeding and increased resistivity from surface projections and recesses created by external additives, leading to inadequate image transfer and fixation.
Innovation Solution
The electrostatic image developing toner includes toner particles with a binder resin and release agent, along with external additives A and B, where external additive A is present on the surface and external additive B is an aggregate of multiple particles, maintaining an average circularity of 0.8 to 0.94 and a release agent coverage of 5-30% on the toner surface, facilitating effective release agent bleeding and improved fixability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external additives are added to create surface projections and recesses, then image transfer quality is improved, but toner resistivity increases leading to poor low-temperature fixability
Solution Approach 1:
The patent applies local quality by differentiating the surface structure of toner particles: smooth regions (5-30 area %) provide low resistivity for good fixability, while projected regions (containing external additives) provide good image transfer quality. This spatial differentiation of surface properties resolves the contradiction between image transfer quality and low-temperature fixability.
Solution Approach 2:
The patent uses composite materials by combining toner particles with a specific surface structure (smooth + projected regions) with external additives having controlled particle sizes (0.5-5 μm for first additive, 0.05-1 μm for second additive). This composite structure achieves both good image transfer (through projected regions) and low-temperature fixability (through smooth regions with controlled resistivity).
2Reliability
If release agent coverage is increased to improve fixability, then low-temperature fixability is improved, but image transfer quality may deteriorate due to excessive bleeding
Solution Approach 1:
The patent optimizes the release agent coverage parameter to a specific range (5-30 area %) on the toner particle surface. This parameter optimization ensures sufficient release agent bleeding for good low-temperature fixability while preventing excessive bleeding that would deteriorate image transfer quality.
3Ease of operation
If toner particle circularity is increased to improve flow properties, then handling is improved, but surface area for release agent distribution is reduced
Solution Approach 1:
The patent creates local quality variations on the toner particle surface by forming both smooth regions and projected regions. This allows the particle to maintain good flow properties (through near-circular overall shape) while providing sufficient surface area for release agent distribution (through the composite surface structure with smooth regions).
Data Source
AI summary
An electrostatic image developing toner includes toner particles including a binder resin and a release agent, an external additive A, and an external additive B. At least the external additive A is present on the surface of the toner particles. At least the external additive B is present on the external additive A. The external additive B is an aggregate of two or more particles. The toner particles have an average circularity of 0.8 or more and 0.94 or less. The amount of the release agent present at the surface of the toner particles is 5 area % or more and 30 area % or less based on the total surface area of the toner particles.