Crash Cooling Method for Chemically Prepared Toner
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Solution Overview
Problem
Existing crash cooling methods for chemically prepared toners in electrophotography result in non-uniform crystalline domains and high water usage, leading to variability in toner performance and increased manufacturing costs.
Innovation Solution
A crash cooling method involving the addition of hot toner slurry to chilled water in an external reactor, with a ratio of hot toner slurry to chilled water ranging from 1:0.60 to 1:0.90 by weight, achieving a cooling rate of less than 0.8° C./min, which helps in controlling the cooling rate and reducing water usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an amount of cooling water equivalent to the reactor batch of toner is added in a crash cooling step, then the toner can be cooled effectively, but the quantity of toner that can be produced from a single reactor batch is limited
Solution Approach 1:
The cooling process is divided into two distinct stages: first, rapid cooling using a small amount of chilled water (10-40% of slurry weight) to achieve quick temperature reduction; second, slower cooling in the remaining slurry to complete the process. This segmentation allows effective cooling while maintaining high productivity by using minimal cooling water.
2Speed
If hot toner slurry is put into a reactor containing ice for crash cooling, then rapid cooling is achieved, but non-uniform crystalline domains and variability in crystalline domains across the toner batch are produced
Solution Approach 1:
The patent optimizes the cooling rate parameter to be less than 0.8°C/min, which is slower than conventional ice-bath methods. This controlled parameter change prevents thermal shock and ensures uniform crystalline domain formation throughout the toner batch, eliminating the variability caused by rapid ice-based cooling.
3Temperature
If an equivalent amount of cold water is used in crash cooling, then the hot toner slurry can be cooled, but a significant amount of water that has to be disposed of or reclaimed is generated, incurring higher manufacturing costs
Solution Approach 1:
The patent changes the water-to-slurry ratio parameter from 1:1 (conventional) to 0.60-0.90:1 (optimized), reducing cooling water consumption by 10-40%. This parameter optimization maintains adequate cooling capability while significantly reducing water waste and associated disposal or reclamation costs.
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
This method produces toners with uniform crystalline domains and reduced water waste, enhancing print quality and efficiency while lowering production costs without compromising toner performance.
Implementation Method 1
the hot toner slurry is added to the chilled cooling water in an external reactor to crash cool the toner particles
Implementation Method 2
The toner prepared using this crash cooling method is cooled at a rate of less than 0.8° C./min
Implementation Method 3
This method produces toners with uniform crystalline domains
Data Source
AI summary
The present disclosure relates generally to a method to make a chemically prepared toner that employs a crash cooling process. In the crash cooling process, an amount of hot toner slurry is added to an external reactor holding an amount of chilled cooling water, wherein the temperature of the chilled cooling water in the external reactor is from about 8° C. to about 25° C. The amount of the chilled cooling water in the external reactor is about 10% to about 40% lower compared to the amount of the added hot toner slurry. Toner prepared using this crash cooling method is cooled at a rate of less than 0.8° C./min. Polyester toners and polyester core shell toners having a borax coupling agent between the toner core and toner shell made from this crash cooling processes using less water results in an improvement to the toner's print density and usage efficiency.