Core-Shell Non-Magnetic Toner for Low-Temp Fixing Stability
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Solution Overview
Problem
Existing electrophotographic toners face challenges in achieving good fixing performance in low temperature ranges, preservation stability at high temperatures, and blocking resistance, particularly in non-magnetic one-component developing toners without magnetic powders.
Innovation Solution
The toner consists of toner core particles coated with a shell layer formed from spherical resin particulates containing charge controlling resin, with a smooth outer surface and internal cracks, ensuring adhesion and fixing performance without magnetic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional toners with magnetic materials and complex structures are used, then good fixing performance and preservation stability can be achieved, but the toner complexity increases and magnetic materials are required
Solution Approach 1:
The invention extracts and removes the magnetic material component from the toner system, creating a non-magnetic one-component developing toner. This extraction eliminates the need for magnetic materials while maintaining essential toner functions through a simplified core-shell structure with binder resin and charge controlling agent
Solution Approach 2:
The invention uses composite material structure with a core-shell configuration where the core contains binder resin and the shell contains charge controlling agent. This composite structure achieves both fixing performance (through binder resin) and preservation stability (through charge controlling agent) without requiring magnetic materials
2Reliability
If core-shell structured toner is used, then good fixing performance in low temperature range and preservation stability at high temperature are achieved, but the manufacturing complexity increases
Solution Approach 1:
The invention optimizes the glass transition temperature parameter of the binder resin (Tg: 40°C to 70°C) and the shell material (Tg higher than core binder resin) to achieve both low-temperature fixing performance and high-temperature preservation stability. This parameter optimization allows the core-shell structure to function effectively across temperature ranges while simplifying manufacturing by focusing on material selection rather than complex process control
3Ease of operation
If inorganic micropowder is added to toner, then flowability and cleanability are improved, but the toner particle complexity and potential aggregation increase
Solution Approach 1:
The invention places the charge controlling agent specifically in the shell layer surrounding the binder resin core, creating local functional zones. This local quality approach provides flowability and cleanability at the particle surface (shell) while maintaining uniform composition and preventing aggregation in the bulk material
Data Source
AI summary
A non-magnetic one-component developing toner comprises toner particles each including a toner core particle containing binder resin and a shell layer coating the toner core particle, and the toner particle contains no magnetic powder. The shell layer is formed using spherical resin particulates containing charge controlling resin. The toner particles have an average particle size of 6 μm or more and 8 μm or less, and when a surface of the toner particle is observed using a scanning electron microscope, a structure derived from the spherical resin particulates is not observed in the shell layer, and the outer surface of the shell layer is smoothed. When a cross section of the toner particle is observed using a transmission electron microscope, a crack derived from an interface between the resin particulates is observed inside the shell layer, in a direction substantially perpendicular to a surface of the toner core particle.