Colored Polymer Particles for Electrophoretic Displays
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Solution Overview
Problem
Current electrophoretic displays (EPDs) lack a bright full-color system and require complex cell structures and drive schemes, and existing colored particles are difficult to disperse in non-polar media without leaching color.
Innovation Solution
Development of specifically engineered colored polymer particles with surface functionality for charge retention, synthesized through emulsion polymerization and surface modification, allowing for independent control of color, charge, and size, and dispersion in dielectric organic media for use in electrophoretic displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If colored particles are used in EPDs to achieve full-color display, then color capability is improved, but particle preparation complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines multiple functions into a single particle system: the polymer particle serves as both the colored element and the charge-carrying electrophoretic component. The dye is integrated within the particle matrix during polymerization, eliminating the need for separate coloring steps and complex multi-component systems. This merging of functions simplifies manufacturing while enabling full-color display capability.
Solution Approach 2:
The invention uses composite polymer particles where the matrix consists of polymer chains with embedded dye molecules. The composite structure allows the particle to simultaneously provide color, charge, and structural integrity. The crosslinked polymer network traps the dye molecules, creating a stable composite that is easy to manufacture and maintains color stability without leaching.
2Adaptability or versatility
If colored particles are dispersed in non-polar media to achieve full-color EPD, then color display is improved, but color leaching occurs
Solution Approach 1:
The patent creates a composite particle where the polymer matrix and crosslinked network physically trap the dye molecules. This composite structure prevents dye leaching into the non-polar dispersant medium while maintaining color display functionality. The crosslinked network acts as a containment barrier that is impermeable to the dye molecules.
Solution Approach 2:
The patent applies local quality modification by creating different regions within the particle: a hydrophobic polymer matrix region that is compatible with non-polar media, and a localized dye-trapping region within the crosslinked network. This spatial differentiation allows the particle to function in non-polar media without color leaching, as the dye is confined to specific localized regions.
3Adaptability or versatility
If complex cell structures and drive schemes are used to achieve full-color EPD, then color capability is improved, but device complexity increases
Solution Approach 1:
The patent segments the color generation function at the particle level rather than at the device level. Each particle is independently colored with specific dyes (red, green, blue), allowing single-pixel color control. This segmentation eliminates the need for complex multi-layer cell structures and sophisticated drive schemes, as color is determined by the particle composition itself rather than by complex electrode patterning.
Solution Approach 2:
The patent makes the polymer particle universal by designing it to perform multiple functions simultaneously: it serves as the electrophoretic charge carrier, the colored display element, and the structural component. This multi-functionality at the particle level simplifies the overall device architecture, as a single particle type with varying dye content can replace complex multi-component systems and elaborate cell structures.
4Manufacturing precision
If polymer particles are synthesized through emulsion polymerization and surface modification, then particle control is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating the dye molecules into the polymerization process itself, before the particles are formed. The dye-containing monomers are polymerized directly into the particle matrix during the emulsion polymerization step, rather than adding dye separately afterward. This preliminary incorporation simplifies the overall process by eliminating separate coloring steps while maintaining precise particle size control.
Solution Approach 2:
The patent uses parameter changes in the emulsion polymerization process (such as monomer concentration, initiator amount, temperature, and water content) to precisely control particle size and dye distribution. By optimizing these parameters, the process achieves manufacturing precision in particle characteristics without requiring complex additional steps. The crosslinking parameter is also adjusted to control the network structure and dye-trapping capability.
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 solution enables the production of high-quality, full-color EPDs with excellent image quality, optical clarity, and stable color retention, achieving faster response times and consistent performance without color leaching into non-polar solvents.
Implementation Method 1
coloring the polymer particles by addition of at least one polymerisable dye, polymerising the polymerisable dye
Implementation Method 2
If a voltage is applied between the electrodes, charged particles move to the electrode of opposite polarity
Data Source
AI summary
This invention relates to colored polymer particles preferably with surface functionality for charge retention, a process for their preparation, the use of these particles for the preparation of an electrophoretic device, and to color electrophoretic displays comprising such particles.