Composite Polyester Toner for Charge Stability in Humid Conditions
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Solution Overview
Problem
Crystalline polyester-based toners experience charge retention issues in high-temperature, high-humidity environments, leading to unstable image density and fixing performance.
Innovation Solution
A toner composition incorporating both crystalline and amorphous polyester resins, with inorganic fine particles distributed within the crystalline resin fraction to enhance charge stability and fixing performance, where the area ratio of inorganic fine particles to crystalline polyester resin exceeds 0.2, maintaining charge stability and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline polyester resin is used as binder resin, then low-temperature fixability is improved, but charge retention performance deteriorates in high-temperature high-humidity environments
Solution Approach 1:
The invention uses a composite binder resin system combining crystalline polyester resin and amorphous polyester resin in specific proportions (crystalline: 10-70 mass%, amorphous: 30-90 mass%). This composite structure allows the crystalline component to provide low-temperature fixability while the amorphous component maintains charge retention stability in humid environments, resolving the contradiction between fixing performance and charge stability.
2Stability of the object's composition
If inorganic fine particles are added to crystalline polyester, then storage stability is improved, but charge stability deteriorates due to lower resistance
Solution Approach 1:
The invention creates a triple-composite structure: inorganic fine particles (silica, alumina, or titania) are dispersed within the crystalline polyester resin, which itself is combined with amorphous polyester resin. This hierarchical composite structure ensures that inorganic particles provide storage stability through crystallization promotion, while the amorphous polyester matrix maintains overall charge stability by compensating for the lower resistance of the crystalline phase.
Solution Approach 2:
The invention applies local quality by differentiating the functional roles of different resin phases: the crystalline polyester resin with inorganic particles provides localized structural stability and low-temperature melting, while the amorphous polyester resin provides the continuous matrix that maintains charge retention. This spatial differentiation of functions resolves the contradiction between storage stability and charge stability.
3Temperature
If crystalline resin is used to achieve low-temperature fixability, then fixing performance is improved, but image density stability deteriorates due to charge variation
Solution Approach 1:
The composite binder resin system maintains consistent charge properties across varying environmental conditions, ensuring stable image density. The amorphous polyester component acts as a buffer that prevents charge fluctuation, while the crystalline component enables low-temperature fixing, thus achieving both fixing performance and image density stability simultaneously.
Data Source
AI summary
A toner comprising a toner particle containing a binder resin, a wax, and inorganic fine particles, wherein the binder resin contains a crystalline polyester resin and an amorphous polyester resin, and, in a cross section of the toner particle, when Sc represents an area taken up by the crystalline polyester resin and S1 represents an area taken up by the inorganic fine particles that are present in the crystalline polyester resin portion, Sc and S1 satisfy the relationship S1/Sc≥0.2.