Coloured 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, with existing methods for preparing colored particles being cumbersome and unsuitable for non-polar media.
Innovation Solution
A batch polymerization process is used to create colored polymer particles by reacting polymerizable dyes with monomers and steric stabilizers in a non-aqueous solvent, allowing for easy dispersion in non-polar media and irreversible dye entrapment, enabling high electrophoretic mobility and color stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If complex cell structures and drive schemes are used to achieve full-color EPD, then color display capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into a single particle system. Colored polymer particles simultaneously provide color display, electrophoretic mobility, and stability without requiring separate cell structures or drive schemes for each function. This merging approach achieves full-color display while simplifying the overall device architecture.
Solution Approach 2:
The colored polymer particles serve multiple purposes: they provide color through their chromophoric groups, enable electrophoretic movement through charged groups, and ensure stability through the polymer matrix. This multi-functionality eliminates the need for separate specialized components for each function.
2Ease of manufacture
If aqueous colloids are used for particle preparation, then particle formation is simplified, but compatibility with non-polar media deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of the dispersion medium from aqueous to non-aqueous. By conducting polymerization directly in non-polar media, the resulting particles are inherently compatible with non-polar dispersants, eliminating the need for media conversion while maintaining ease of manufacture.
Solution Approach 2:
The patent creates composite polymer particles that incorporate both the chromophoric groups for color and charged groups for electrophoretic mobility within a single polymer matrix. This composite structure achieves both color display and electrophoretic functionality while maintaining compatibility with non-polar media.
3Illumination intensity
If dyes are used for particle coloring, then color brightness is improved, but color leaching in dispersant occurs
Solution Approach 1:
The patent incorporates the chromophoric groups into the polymer particles during the polymerization process itself, before the particles are dispersed in the final medium. This preliminary incorporation ensures that the color is permanently bound to the particle structure, preventing leaching while maintaining brightness.
Solution Approach 2:
The patent ensures continuous color stability by permanently integrating the chromophoric groups into the polymer matrix through covalent bonding during polymerization. This continuous integration prevents color loss or leaching over time, maintaining both brightness and stability.
4Reliability
If multiple processing steps are used to achieve colored particles, then particle performance is improved, but manufacturing time increases
Solution Approach 1:
The patent merges multiple processing steps into a single polymerization reaction. The chromophoric groups, charged groups, and polymer matrix are all formed simultaneously in one step, eliminating the need for sequential processing while maintaining high particle performance.
Solution Approach 2:
The patent performs preliminary incorporation of all necessary functional groups (chromophoric and charged) during the initial polymerization step. This preliminary action eliminates the need for subsequent modification steps, reducing manufacturing time while ensuring optimal particle performance.
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 process produces particles with excellent size control, optical clarity, and electrophoretic switching behavior, enabling cost-effective production of high-quality colored EPD particles suitable for full-color e-paper without the need for aqueous mediums or subsequent drying processes.
Implementation Method 1
A batch polymerisation process is used to create coloured polymer particles by reacting polymerizable dyes with monomers and steric stabilizers
Implementation Method 2
enabling high electrophoretic mobility and color stability
Data Source
AI summary
This invention relates to coloured 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, colour electrophoretic displays comprising such particle, and new water-soluble dyes.