Hard Coating Composition for Flexible Displays
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Solution Overview
Problem
Existing hard coatings for display devices, particularly those using optical plastic substrates, face challenges in achieving high hardness and scratch resistance comparable to reinforced glass while maintaining flexibility and impact resistance, with typical photocurable composite resins exhibiting curling issues and insufficient flexibility.
Innovation Solution
A hard coating composition comprising a silazane compound, a polyfunctional (meth)acryl-based dendrimer compound or polyfunctional urethane (meth)acrylate with a cyclohexyl group, a photoinitiator, and a solvent, which controls curing density to enhance scratch resistance, hardness, and flexibility, and is applied to form a hard coating film suitable for flexible display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a typical photocurable composite resin is used to form a hard coating on a plastic substrate, then hardness and scratch resistance are improved, but curling occurs due to shrinkage upon curing and flexibility is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the coating resin by incorporating silazane compounds and specific polyfunctional acrylates with controlled functional group densities. This modifies the curing shrinkage characteristics and crosslinking density, enabling the coating to achieve high hardness while maintaining flexibility and preventing curling.
Solution Approach 2:
The patent creates a composite coating system combining silazane compounds, polyfunctional acrylates, and photoinitiators. This composite formulation achieves synergistic effects where the silazane provides structural integrity and hardness, while the polyfunctional acrylate matrix maintains flexibility and controls shrinkage during curing.
2Strength
If a typical photocurable composite resin is used to form a hard coating on a plastic substrate, then hardness and scratch resistance are improved, but curling significantly occurs due to shrinkage upon curing
Solution Approach 1:
The patent adjusts the functional group density and molecular weight parameters of the polyfunctional acrylate components to control polymerization shrinkage. By optimizing these parameters, the coating achieves high scratch resistance while minimizing volumetric shrinkage that causes curling.
Solution Approach 2:
The patent creates different local properties within the coating by incorporating silazane compounds that provide localized reinforcement and shrinkage compensation. This local quality variation allows the coating to resist scratches while maintaining overall shape stability.
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 coating composition achieves superior scratch resistance, hardness, and flexibility, preventing curling and enabling the use of the hard coating film in flexible display devices without compromising mechanical properties.
Implementation Method 1
a hard coating composition comprising a silazane compound of Chemical Formula 1 or 2 below, a polyfunctional (meth)acryl-based dendrimer compound of Chemical Formula 3 below, or a polyfunctional urethane (meth)acrylate having a cyclohexyl group, a photoinitiator, and a solvent
Data Source
AI summary
Described is a hard coating composition composed of a silazane compound, a polyfunctional (meth)acryl-based dendrimer compound or a polyfunctional urethane (meth)acrylate having a cyclohexyl group, a photoinitiator and a solvent, and to a hard coating film, a window film, and a display device including the same, thus exhibiting superior scratch resistance, hardness and flexibility.