Supercritical Fluid Microencapsulation of Dye into Latex
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Solution Overview
Problem
Existing methods for producing color toners using emulsion aggregation techniques often result in poorly dispersed pigments, leading to lower image density and limited color gamut, and involve the use of harmful organic solvents.
Innovation Solution
A process involving the polymerization of latex particles, dispersion in de-ionized water, contact with dyes and surfactants, and the use of supercritical fluids to microencapsulate colorants, ensuring even distribution and reducing solvent use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If emulsion aggregation techniques are used to produce color toners, then the production process is simple and efficient, but the pigment dispersion is poor leading to lower image density and limited color gamut
Solution Approach 1:
The patent applies preliminary action by pre-encapsulating the colorant within latex particles before the aggregation process. This is achieved by forming latex particles in the presence of colorant, allowing the colorant to be incorporated into the particle structure during polymerization. This preliminary encapsulation ensures uniform colorant distribution throughout the final toner particles, resolving the pigment dispersion issue while maintaining production efficiency
Solution Approach 2:
The patent utilizes parameter changes by controlling polymerization conditions such as monomer composition, initiator type and concentration, and reaction temperature to optimize colorant encapsulation. By adjusting these parameters, the process achieves both efficient production and superior pigment dispersion, as the polymerization conditions directly influence how colorant molecules are distributed and trapped within the forming latex particles
2Ease of manufacture
If traditional dye incorporation methods using organic solvents are used, then dye transport into latex particles is facilitated, but harmful organic solvents are used which are environmentally harmful
Solution Approach 1:
The patent applies the extraction principle by completely removing harmful organic solvents from the dye incorporation process. Instead of using solvent-based methods, the invention incorporates colorant directly into latex particles through aqueous-phase polymerization or by adding colorant to pre-formed latex in water-based systems. This eliminates the need for toxic solvents like dichloromethane while maintaining effective colorant incorporation through alternative mechanisms such as diffusion in aqueous media or in-situ encapsulation
Solution Approach 2:
The patent uses water as an intermediary medium to facilitate colorant transport into latex particles, replacing harmful organic solvents. Water serves as the continuous phase in emulsion systems and enables colorant diffusion and incorporation without the environmental hazards of organic solvents. This intermediary approach maintains manufacturing efficiency while eliminating toxic substance use
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 process enhances color homogeneity, increases the color gamut, and reduces the amount of colorant needed, while eliminating the use of harmful solvents, resulting in improved toner quality and environmental sustainability.
Implementation Method 1
contacting the latex dispersion with at least one dye and surfactant; adding a supercritical fluid to the latex dispersion to form a latex dye mixture; removing the supercritical fluid from the latex dye mixture
Data Source
AI summary
The present disclosure provides methods for incorporating a dye into latex particles via a supercritical fluid microencapsulation technique, in order to achieve improved dispersion of a colorant in the latex and an increase in color gamut.