Emulsion Aggregation Toner Particle Size Distribution Control
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Solution Overview
Problem
Conventional toner compositions for electrophotographic machines have difficulty achieving a narrow charge distribution and particle size distribution, which affects image quality and printing properties.
Innovation Solution
A method of forming toner particles by creating pre-shell aggregates through a controlled mixing process with specific tip speed adjustments and adding a shell latex to achieve a targeted average particle diameter and distribution, resulting in toner particles with a core-shell structure and improved size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional toner compositions are used, then the manufacturing process is simple, but the particle size distribution is broad and charge distribution is poor
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the impeller tip speed during the mixing process. The tip speed is not maintained at a constant value but is varied in response to changing particle size conditions. Specifically, the tip speed is adjusted to meet the formula: tip speed = 1644 ft/min - 204.9(ft/(min*μm))*average particle diameter(μm). This dynamic adjustment allows the system to adapt to the evolving particle size distribution and achieve narrow final distribution while controlling the complexity of the mixing process.
Solution Approach 2:
The patent implements feedback by monitoring the average particle diameter during the mixing process and using this information to adjust the impeller tip speed. The system continuously measures particle size and modifies the mixing parameters accordingly, creating a closed-loop control system that ensures achievement of the target particle size distribution while maintaining manageable process complexity.
2Manufacturing precision
If additive blend process and formulation optimization are used, then toner charge distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the impeller tip speed parameter during the mixing process to achieve optimal particle size distribution, which directly influences charge distribution. By controlling the mixing parameters (tip speed, mixing time, temperature) and using the specific formula relating tip speed to particle diameter, the process achieves narrow charge distribution without requiring complex additive blends or formulation optimizations, thus maintaining ease of manufacture.
3Manufacturing precision
If physically separating particles via wet sieving is used, then particle size distribution is narrowed, but production time increases
Solution Approach 1:
The patent applies preliminary action by performing the particle size control during the main mixing and aggregation process itself, rather than attempting to correct particle size distribution after the fact through separate wet sieving operations. By proactively controlling the aggregation process with dynamic tip speed adjustment, the system achieves narrow particle size distribution in-situ, eliminating the need for subsequent time-consuming separation operations.
4Reliability
If increasing sphericity of toner particles is used, then printing properties are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies dynamics by using dynamic impeller tip speed adjustment during the aggregation process to control particle morphology. The varying tip speed creates controlled shear forces that promote spherical particle formation. This dynamic approach to sphericity control integrates into the main mixing process rather than requiring separate operations, thus improving printing properties without significantly increasing manufacturing complexity.
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 method produces toner particles with a narrow particle size distribution and improved charge distribution, leading to enhanced image quality and stability in electrophotographic machines.
Implementation Method 1
performing pre-shell aggregation while homogenizing the pre-shell aggregate mixture with the impeller at an initial tip speed
Implementation Method 2
the reactor comprising a mixing impeller and a heating jacket
Implementation Method 3
adding a shell latex to the pre-shell aggregates; and forming shells around the pre-shell aggregates
Data Source
AI summary
A method of making toner particles that includes forming a pre-shell aggregate mixture by adding to a reactor pre-shell aggregate ingredients, the includes a latex resin, the reactor having a mixing impeller and a heating jacket; performing pre-shell aggregation while homogenizing the pre-shell aggregate mixture with the impeller at an initial tip speed to form pre-shell aggregates; decreasing the tip speed to a second tip speed when the pre-shell aggregates reach a target intermediate average particle diameter; and then decreasing the tip speed at one or more intervals between when the pre-shell aggregates reach the target intermediate average particle diameter and when the pre-shell aggregates reach a target final average particle diameter so that the tip speed meets the following formula:tip speed=1644ft/min−204.9(ft/(min*μm))*average particle diameter(μm).