Flexible Hardcoat Nanoparticle Composite for Foldable Displays
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Solution Overview
Problem
Existing flexible display technologies face challenges in maintaining optical properties and providing sufficient scratch resistance while withstanding folding and bending without visible damage, especially around tight bend radii.
Innovation Solution
A flexible hardcoat composition incorporating multifunctional (meth)acrylate monomers and a nanoparticle mixture with a balance of reactive and non-reactive nanoparticles, which are surface-treated to enhance mechanical strength and durability, is applied to a transparent substrate, maintaining optical clarity and flexibility while offering superior abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hard-coated plastic substrates or hard-coated colorless transparent polyimide films are used to provide high hardness and good scratch resistance, then scratch resistance is improved, but the ability to withstand folding events around tight bend radius deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the hardcoat by incorporating specific ratios of cyclic carbonate monomers (10-40 wt%), cyclic carboxylate monomers (5-30 wt%), and oligomers (30-60 wt%). This compositional parameter adjustment enables the hardcoat to achieve both high scratch resistance (6H pencil hardness) and flexibility to withstand folding events around tight bend radii without visible damage
Solution Approach 2:
The patent creates a composite hardcoat material system combining multiple components: cyclic carbonate monomers, cyclic carboxylate monomers, oligomers, and photoinitiators. This composite material approach allows the hardcoat to simultaneously exhibit high hardness for scratch resistance and elastic properties for flexibility during folding, resolving the contradiction between strength and reliability
2Adaptability or versatility
If conventional glass cover sheets are replaced with flexible cover sheets to enable curved and folded displays, then adaptability is improved, but scratch resistance and puncture resistance deteriorate
Solution Approach 1:
The patent adjusts the molecular weight and functional group ratios of the polymer components to achieve optimal balance between flexibility and hardness. The specific parameter ranges (cyclic carbonate monomers 10-40 wt%, cyclic carboxylate monomers 5-30 wt%) enable the flexible cover sheet to maintain 6H pencil hardness while being adaptable to curved and folded display configurations
Solution Approach 2:
The patent develops a composite polymer system combining cyclic carbonate and cyclic carboxylate monomers with specific oligomers. This composite material provides both the flexibility needed for curved displays and the hardness for scratch resistance, overcoming the limitations of conventional flexible materials
3Shape
If the flexible cover sheet is made thinner to reduce visibility of creases after folding, then appearance quality is improved, but mechanical strength and puncture resistance deteriorate
Solution Approach 1:
The patent optimizes the thickness and crosslinking density parameters of the hardcoat layer. By controlling the monomer and oligomer ratios within specific ranges, the hardcoat achieves high mechanical strength and puncture resistance even at thin thicknesses (1-10 micrometers), preventing crease visibility while maintaining structural integrity
4Strength
If the hardcoat is made harder to improve scratch resistance, then hardness is improved, but flexibility and ability to withstand bending deteriorate
Solution Approach 1:
The patent precisely controls the functional group content and molecular weight distribution of the polymer components. The cyclic carbonate monomers (10-40 wt%) provide crosslinking for hardness, while cyclic carboxylate monomers (5-30 wt%) and oligomers maintain chain flexibility. This parameter optimization achieves 6H pencil hardness while preserving flexibility for bending applications
Solution Approach 2:
The patent creates a composite polymer network where cyclic carbonate and cyclic carboxylate monomers work synergistically with oligomers. This composite structure provides both the hardness needed for scratch resistance (6H pencil hardness) and the flexibility required for bending and folding applications
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 hardcoat composition effectively withstands bending and folding without visible defects, maintains optical properties, and exhibits superior flexibility and abrasion resistance, ensuring the display remains intact and functional through extensive bending cycles.
Implementation Method 1
The non-reactive nanoparticle have a non-reactive surface treatment with a compound having a general formula R—SiR′m(OR′′)3-m
Implementation Method 2
one or more multifunctional (meth)acrylate monomers
Data Source
AI summary
A hardcoat composition includes one or more multifunctional (meth)acrylate monomers, and a nanoparticle mixture dispersed within the one or more multifunctional (meth)acrylate monomers. The nanoparticle mixture includes a first population of reactive nanoparticles. The first population of reactive nanoparticles have an average particle diameter in a range from 5 nm to 60 nm, and a second population of non-reactive nanoparticles. The second population of non-reactive nanoparticles have an average particle diameter in a range from 5 nm to 60 nm.