Toner Charge Control via Post-Coalescence Adhesion
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Solution Overview
Problem
Existing toner production methods face challenges in maintaining effective triboelectric charging properties, particularly when incorporating charge control agents into emulsion aggregation toners, leading to a drastic decrease in charge and impacting toner performance.
Innovation Solution
A process involving the addition of charge control agents to toner particles after coalescence, followed by high shearing and heating above the glass transition temperature, ensures the agents adhere to the particles, enhancing charging characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge control agents are incorporated into emulsion aggregation toners during particle formation, then the toner particles can be produced with charging properties, but the charging properties are lost when the additive package is added to the particle, causing a drastic decrease in charge
Solution Approach 1:
The charge control agent is incorporated into the toner particle during the emulsion aggregation process, before the additive package is introduced. This preliminary incorporation ensures the charge control agent is already positioned on the particle surface when the additive package is added, preventing loss of charging properties despite the subsequent addition of other components
Solution Approach 2:
The patent modifies the sequence and timing of parameter changes during toner production. By controlling when the charge control agent is introduced relative to other additives, and by adjusting processing conditions such as mixing intensity and temperature, the patent maintains the charge control agent's effectiveness while incorporating all necessary toner components
2Manufacturing precision
If charge control agents are added in small amounts (0.01-5 wt%), then the polarity and distribution of charge on toner can be controlled, but the amount of charge control agent is small compared to other components, making incorporation difficult
Solution Approach 1:
The charge control agent is introduced early in the particle formation process during emulsion aggregation, before the toner particle reaches its final composition. This preliminary action allows the charge control agent to be incorporated into the forming particle structure, ensuring uniform distribution despite the small quantity (0.01-5 wt%) relative to other components
Solution Approach 2:
The charge control agent is concentrated at specific locations on the toner particle surface during the aggregation process, creating local zones of charge control functionality. This localized incorporation is more effective than uniform distribution and works efficiently at very low concentrations
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 process results in toner particles with increased negative charge, improving triboelectric charging and extending toner life, while maintaining existing aggregation and coalescence processes, thus enhancing imaging performance.
Implementation Method 1
adding a dispersion to the toner slurry, the dispersion comprising one or more charge control agents
Implementation Method 2
heating the toner slurry to above a glass transition temperature of the toner particles while mixing
Data Source
AI summary
A toner having charge control agents which impart excellent triboelectric charging characteristics. In embodiments, the toner particles are made by a process in which charge control agent is added and adhered to the particle surface through washing steps and is maintained through the drying steps. The process of the present embodiments impart desirable charging characteristics to the toner particles.