Microcapsule Double-Shell Structure for Electrophoretic Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrophoretic display devices using microcapsules with gelatin and gum arabic shells exhibit low capsule strength, high leakage current, and decreased contrast when exposed to high temperature and high humidity conditions, leading to performance degradation and instability.
Innovation Solution
The development of microcapsules with a double-shell structure, comprising an inner shell made of a mercapto group-containing amino resin and an outer shell made of a melamine-crosslinked epoxy resin, which provides enhanced capsule strength and solvent resistance, and the use of a specific polysaccharide with a polymer structure formed by bonding galactose and arabinose units to improve shell formation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microcapsules with gelatin and gum arabic shells are used, then the microcapsules can be easily manufactured and have good biocompatibility, but the capsule strength is low and they degrade under high temperature and high humidity conditions
Solution Approach 1:
The patent applies composite materials by combining gelatin and gum arabic to form a multi-component shell structure. This composite approach leverages the complementary properties of each material: gelatin provides biocompatibility and ease of manufacture, while gum arabic enhances shell strength and stability under harsh conditions. The synergistic combination resolves the contradiction between ease of manufacture and capsule strength.
2Ease of manufacture
If microcapsules with gelatin and gum arabic shells are used, then the manufacturing process is simple, but the leakage current increases and contrast decreases under high temperature and high humidity conditions
Solution Approach 1:
The composite shell structure made of gelatin and gum arabic provides both ease of manufacture and improved reliability. The gum arabic component specifically addresses the reliability issue by forming a more stable shell that resists degradation under high temperature and high humidity conditions, preventing leakage current and maintaining display contrast while preserving the manufacturing simplicity of the coacervation method.
3Ease of operation
If microcapsules are preserved at room temperature as coating solution, then the storage is simple, but the coating solution develops rotten smell and dispersion leaks after a few days
Solution Approach 1:
The composite shell of gelatin and gum arabic provides exceptional storage stability while maintaining storage simplicity. The gum arabic component acts as a natural preservative and structural stabilizer that prevents dispersion leakage and prevents putrefaction (rotten smell) during storage at room temperature, allowing the coating solution to be stored for extended periods without degradation while remaining easy to store and apply.
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 proposed microcapsules demonstrate improved capsule strength, reduced leakage current, and maintained high contrast and display performance even after prolonged exposure to high temperature and high humidity conditions, with the ability to be preserved stably over time without significant degradation.
Implementation Method 1
an inner shell made of a mercapto group-containing amino resin and an outer shell made of a melamine-crosslinked epoxy resin
Implementation Method 2
a specific polysaccharide with a polymer structure formed by bonding galactose and arabinose units
Implementation Method 3
the behavior of electrophoretic particles, for example, when a voltage is applied to a dispersion in which the electrophoretic particles are dispersed in a solvent
Data Source
AI summary
The microcapsules for electrophoretic display devices according to the present invention each enclose a dispersion containing electrophoretic particles and a solvent in a shell having an inner shell made of a mercapto group-containing amino resin and an outer shell made of an epoxy resin. Alternatively, the microcapsules for electrophoretic display devices according to the present invention each have a capsule strength of 0.6 MPa or higher. These microcapsules are produced by dispersing a dispersion containing electrophoretic particles and a solvent as a core substance in a water-based medium, and subsequently forming at least one shell on the surface of the core substance. These microcapsules can be used, as their applications, for sheets for electrophoretic display devices, electrophoretic display devices using the sheets, and electronic equipments using the electrophoretic display devices.