Emulsion Aggregation Toner pH Control
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Solution Overview
Problem
Existing emulsion aggregation toner compositions often result in print defects such as background, spots, and smudges due to colorant and non-coalesced latex particles on the surface of toner particles, leading to uneven charge distribution.
Innovation Solution
Lowering the coalescence pH during toner synthesis significantly reduces the amount of colorant on the surface of emulsion aggregation toner particles, resulting in a smoother surface and improved charging capabilities, which minimizes print defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coalescence pH is used during toner synthesis, then the toner particles form with colorant on the surface, but the charge distribution becomes uneven and print defects occur
Solution Approach 1:
The patent applies parameter changes by adjusting the coalescence pH to a specific range (pH 4.0-5.0) during the toner synthesis process. This pH adjustment controls the surface properties of the toner particles, enabling colorant to be incorporated into the particle interior rather than remaining on the surface, thereby achieving both smooth surfaces and uniform charge distribution.
2Quantity of substance
If colorant is present on the surface of EA toner particles, then the toner can be formed, but the charge distribution broadens and charging capability decreases
Solution Approach 1:
The patent changes the pH parameter during coalescence to control colorant distribution. At pH 4.0-5.0, the colorant is effectively incorporated into the toner particle interior while maintaining proper particle formation, resulting in improved charging capability due to the absence of surface colorant that would otherwise interfere with charge uniformity.
3Productivity
If non-coalesced latex particles remain on the toner surface, then the aggregation process is complete, but the surface roughness increases and print quality deteriorates
Solution Approach 1:
The patent adjusts the coalescence pH to promote complete coalescence of latex particles. This pH optimization ensures that all latex particles fully merge during the coalescence stage, eliminating surface roughness caused by uncoalesced particles while maintaining high production efficiency.
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 higher charging capabilities, reducing print defects and enabling the production of robust images that are substantially free of background, spots, and smudges.
Implementation Method 1
The aggregated toner particles are heated to enable coalescence/fusing, thereby achieving aggregated, fused toner particles
Implementation Method 2
The aggregated toner particles are heated to enable coalescence/fusing
Data Source
AI summary
A method of making toner particles, including mixing at least one emulsion of at least one resin, a colorant, an optional wax, and optional additives to form a slurry; heating the slurry to form aggregated particles in the slurry; freezing aggregation of the particles by adjusting the pH; and heating the aggregated particles in the slurry to coalesce the particles into toner particles.