Electrophoretic Particle Coating for Dispersibility and Mobility
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Solution Overview
Problem
Electrophoretic particles in displays exhibit low mobility due to reduced charge when the density of polymer molecules attached to their surfaces is high, affecting their dispersibility and functionality in electrophoretic dispersions.
Innovation Solution
The development of electrophoretic particles with a core particle coated by a layer containing a polymer and a silane coupling agent with a nonionic charged group, which enhances both dispersibility and mobility by controlling the weight fraction and hydrophobicity of the coating layer, allowing for improved charge distribution and stability in the dispersion medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the density of polymer molecules attached to the surface of electrophoretic particles is increased to improve dispersibility, then the dispersibility is improved, but the charge of the particles is reduced, resulting in low mobility
Solution Approach 1:
The patent applies local quality by creating a coating layer with specific local characteristics (silane coupling agent containing nonionic charged groups) on the particle surface, rather than uniformly distributing all functional groups throughout the polymer. This localized functional grouping maintains charge density in specific regions while allowing overall polymer coverage for dispersibility.
Solution Approach 2:
The patent uses composite materials by combining polymer molecules with silane coupling agents that contain nonionic charged groups. This composite structure on the particle surface provides both the dispersibility benefits of polymer coverage and the charge benefits of ionizable groups, resolving the contradiction between these two properties.
2Stability of the object's composition
If a coating layer is added to improve dispersibility, then dispersibility is improved, but the particle charge is reduced, affecting mobility
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the coating layer to include silane coupling agents with nonionic charged groups. This changes the charge density parameter and electrical properties of the coating, enabling both good dispersibility and maintained mobility through appropriate parameter selection.
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 electrophoretic particles to exhibit both excellent dispersibility and mobility, leading to high reliability in electrophoretic dispersions, sheets, devices, and apparatuses, with enhanced performance and stability under various conditions.
Implementation Method 1
when an electric field is applied to a dispersion containing a liquid and fine particles dispersed therein, the fine particles move (electrophoretically migrate) in the liquid because of the Coulomb force. This phenomenon is referred to as electrophoresis.
Implementation Method 2
the fine particles move (electrophoretically migrate) in the liquid because of the Coulomb force
Implementation Method 3
a polymerization site formed by polymerizing a monomer using the polymerizable group as a starting point
Data Source
AI summary
An electrophoretic particle includes a core particle and a coating layer covering at least one portion of the core particle. The coating layer contains a polymer and a silane coupling agent containing a nonionic charged group attached to the surface of the core particle. The polymer contains a silane coupling agent containing a polymerizable group attached to the surface of the core particle and a polymerization site formed by polymerizing a monomer using the polymerizable group as a starting point.