Toner External Additive Particle Size Control
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Solution Overview
Problem
Color toner experiences significant issues with small-size inorganic particles separating from the toner surface and migrating to carriers and photoconductors, leading to deterioration in image quality and developer durability due to mechanical stress in the developing device.
Innovation Solution
A toner formulation incorporating mother particles with a binder resin and an external additive of small-size and large-size inorganic particles, where the large-size particles have a specific diameter and circularity, allowing them to roll on the toner surface and immobilize the small-size particles, preventing separation and adhesion to photoconductors and developing device components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If small-size inorganic particles are added as fluidizer to improve fluidity and chargeability, then development characteristics are improved, but the particles separate from toner surface and migrate to carriers and photoconductors causing image quality deterioration
Solution Approach 1:
The invention uses a composite structure consisting of a toner particle and a shell layer surrounding it. The shell layer is formed by a material different from the toner particle core, creating a composite material system. This composite structure allows the small-size inorganic particles to be embedded within the shell layer rather than being exposed on the toner surface, preventing their separation and migration while maintaining the fluidity benefits they provide.
2Strength
If small-size inorganic particles are embedded in toner surface due to mechanical stress, then physical adhesion force increases, but developability and transferability deteriorate over time
Solution Approach 1:
The invention segments the toner structure into two distinct parts: the toner particle core and the surrounding shell layer. The small-size inorganic particles are specifically located within the shell layer, separated from direct contact with the toner particle surface. This segmentation prevents the mechanical stress-induced embedding that leads to adhesion force increase, thereby maintaining developability and transferability durability over time.
Data Source
AI summary
A toner is provided. The toner comprises mother particles and an external additive covering the mother particles. The mother particles comprise a binder resin, and the external additive comprises inorganic particles. The inorganic particles comprise small-size inorganic particles having an equivalent circle diameter of from 30 to 70 nm and large-size inorganic particles having an equivalent circle diameter of from 150 to 200 nm and a circularity of 0.85 or more. The large-size inorganic particles are 20 to 70 in number per 100 μm2 image area of the toner observed with a field-emission scanning electron microscope.