Toner Core-Shell Structure for Low-Temperature Fixation
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Solution Overview
Problem
Existing electrostatic charge image developing toners have poor low-temperature fixability and toner blocking resistance, leading to potential image defects due to toner aggregation at high temperatures.
Innovation Solution
The development of an electrostatic charge image developing toner with a toner core and a thermosetting resin shell layer, where the toner core contains a binder resin, releasing agent, colorant, and charge control agent, and the shell layer has a high content of thermosetting resin with cationic properties, ensuring excellent low-temperature fixability and blocking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a binder resin with low softening point and low glass transition point is used to achieve low-temperature fixability, then low-temperature fixability is improved, but toner aggregation occurs under high temperature storage
Solution Approach 1:
The toner is divided into two functional parts: a toner core containing the binder resin with low Tm and Tg for low-temperature fixation, and a shell layer containing thermosetting resin with high crosslinking density for heat resistance. This segmentation allows each part to perform its specific function without interfering with the other.
Solution Approach 2:
The toner uses a composite structure combining thermoplastic binder resin (for low-temperature melting and fixation) with thermosetting resin in the shell layer (for high-temperature stability and crosslinking). This composite material approach resolves the contradiction between low-temperature workability and high-temperature stability.
2Temperature
If a releasing agent with low softening point is used to improve low-temperature fixability, then low-temperature fixability is improved, but toner blocking resistance decreases
Solution Approach 1:
The releasing agent is segregated into the toner core rather than being uniformly distributed. This allows the core to provide low-temperature release properties while the shell layer provides blocking resistance through thermosetting resin crosslinking.
Solution Approach 2:
The shell layer acts as a protective film around the toner core, providing a barrier that prevents toner blocking while allowing the core materials to perform their low-temperature fixation function.
3Ease of manufacture
If toner particles aggregate to reduce manufacturing complexity, then manufacturing is simplified, but charge amount decreases and image quality deteriorates
Solution Approach 1:
The toner is manufactured as discrete particles with internal segmentation (core and shell) rather than as aggregated clumps. This maintains charge uniformity while allowing efficient manufacturing through controlled particle formation processes.
Solution Approach 2:
The composite particle structure with distinct core and shell regions allows for controlled manufacturing that preserves charge properties while achieving the desired functional performance.
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 achieves improved low-temperature fixability and reduced toner aggregation, preventing image faults and ensuring high-quality image formation while maintaining toner stability under various environmental conditions.
Implementation Method 1
the shell layer contains a thermosetting resin... A content ratio of the toner component insoluble in tetrahydrofuran is at least 90 mass %
Implementation Method 2
Melt viscosity of the toner at 75° C. is at least 1.0×104 Pa·s and no greater than 1.0×105 Pa·s... low-temperature fixability
Data Source
AI summary
An electrostatic charge image developing toner includes a plurality of toner particles. Each of the plurality of toner particles includes a toner core and a shell layer covering the toner core. The shell layer contains a thermosetting resin. A content ratio of a toner component insoluble in tetrahydrofuran is at least 90 mass % relative to mass of the toner. Melt viscosity of the toner at 75° C. is at least 1.0×104 Pa·s and no greater than 1.0×105 Pa·s. The thermosetting resin is preferably a melamine resin or a urea resin. The toner core preferably contains a binder resin, and the binder resin has a softening point (Tm) of at least 85° C. and no greater than 95° C.