Polymer Hard Coat for Flexible OLED Displays
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Solution Overview
Problem
Commercially available hard coats for flexible plastic OLED displays fail to provide adequate protection due to processing limitations, leading to damage from mild use conditions such as bending and abrasion, and often result in optical defects and delamination.
Innovation Solution
A hard coat comprising at least 49 wt% of additive particles dispersed in a polymerizable monomer, which forms a durable, optically clear coating with low haze and high transmission, capable of bending without breaking or delaminating, and incorporating shape memory polymers for self-healing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hard coats are applied to flexible plastic OLED substrates, then abrasion resistance is improved, but the hard coat causes optical defects and delamination due to processing limitations
Solution Approach 1:
The patent changes the chemical composition parameters of the hard coat by incorporating silane-modified polymers and specific crosslinking agents that enable low-temperature curing. This allows the hard coat to achieve high abrasion resistance while maintaining optical clarity and adhesion, resolving the contradiction between strength and reliability
Solution Approach 2:
The patent creates a composite hard coat system combining silane-modified polymers, crosslinking agents, and optional inorganic fillers. This composite structure provides both the mechanical strength for abrasion resistance and the chemical stability for optical clarity and adhesion, eliminating the defects of conventional single-component hard coats
2Strength
If thicker and harder films are deposited on flexible plastic substrates, then protective capability is improved, but substrate curling increases during processing
Solution Approach 1:
The patent modifies the curing temperature parameter by using silane-based chemistry that cures at lower temperatures compared to conventional hard coats. This reduces thermal strain on the flexible substrate during processing, minimizing curling while still achieving the desired protective capability through controlled crosslinking density
Solution Approach 2:
The patent optimizes the hard coat as a thin film formulation that provides adequate protection without excessive thickness. The silane-modified polymer system achieves high protective capability in thinner films, reducing the strain-induced curling effect on flexible substrates during deposition and processing
3Temperature
If low-temperature processing is used to coat plastic substrates, then substrate damage is prevented, but chemistries and processes are limited reducing hard coat performance
Solution Approach 1:
The patent changes the chemical reactivity parameters by introducing silane-modified polymers with reactive silane groups that can crosslink at lower temperatures. This enables the hard coat to achieve high hardness and strength through silane crosslinking chemistry even when processed at low temperatures suitable for flexible plastic substrates
Solution Approach 2:
The patent replaces thermal curing mechanisms with silane-based crosslinking chemistry that operates effectively at lower temperatures. The silane crosslinking provides the necessary mechanical strength and hardness without requiring the high temperatures that would damage flexible plastic substrates
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 hard coat significantly enhances the tensile modulus of plastic substrates, providing superior scratch and abrasion resistance, maintaining optical clarity, and enabling flexible devices to withstand at least 100,000 bending cycles without damage.
Implementation Method 1
a polymerizable monomer... Upon polymerization the dispersion forms a hard coat
Data Source
AI summary
A dispersion comprised of at least 49 wt % of additive particles, a polymerizable monomer, a dispersant and a solvent. Upon polymerization the dispersion forms a hard coat with a haze of at most 0.5% and a transmission of at least 90%. A hard coat comprises at least 49 wt % of additive particles dispersed in a polymer. A method of making a hard coat comprises forming a dispersion, applying the dispersion to one side of a substrate, and polymerizing the dispersion. The hard coat has a haze of at most 0.5% and a transmission of at least 90%.