Flexible Cover Window Coating for Hardness and Foldability
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Solution Overview
Problem
Conventional cover windows for flexible display devices lack sufficient surface hardness and hardness restoring force, making them vulnerable to external impacts and prone to reduced hardness over time, especially when exposed to UV radiation.
Innovation Solution
A cover window comprising a base film with a coating layer formed from a specific coating solution containing a first monomer derived from Chemical Formula 1, a second monomer, an iodine-based initiator, and a solvent, which provides enhanced hardness and flexibility, allowing the window to be folded and maintain a predetermined level of hardness and restoring force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional cover window material is used, then the manufacturing process is simple, but the cover window lacks sufficient strength to withstand external impacts
Solution Approach 1:
The patent applies composite materials by forming a coating layer with organic-inorganic hybrid structure on the cover window. The coating layer comprises silane-modified polymer chains (organic) and cross-linked inorganic networks (inorganic), creating a composite material that provides enhanced strength and impact resistance while maintaining flexibility.
Solution Approach 2:
The patent utilizes parameter changes by controlling the molecular structure of the coating layer through specific chemical composition ratios (silane content, cross-linking density) and processing parameters (curing temperature, humidity). These parameter adjustments optimize the balance between strength, flexibility, and hardness restoring force.
2Adaptability or versatility
If a rigid cover window material is used, then the surface hardness is high, but the cover window cannot be folded
Solution Approach 1:
The patent employs flexible shells and thin films by creating a thin coating layer (1-10 μm) on the cover window. This thin film structure provides flexibility for folding applications while the cross-linked organic-inorganic hybrid network within the film maintains sufficient surface hardness and protective function.
Solution Approach 2:
The patent achieves the flexibility-hardness balance through parameter changes in the coating layer composition, specifically controlling the silane modification degree and cross-linking density. These parameter adjustments enable the coating to be flexible enough for folding while restoring hardness after deformation.
3Strength
If a touch panel integrated structure is used, then the user interface is improved, but the cover window surface is more frequently contacted and requires stronger strength
Solution Approach 1:
The patent applies beforehand cushioning by forming a protective coating layer with high hardness restoring force on the cover window surface. This coating layer acts as a cushioning protective barrier that absorbs and dissipates external impacts and finger contact stresses before they reach the underlying display panel, preventing damage in advance.
Solution Approach 2:
The patent uses composite materials in the coating layer to provide both the hardness needed for impact resistance and the flexibility needed for touch panel applications. The organic-inorganic hybrid composite structure creates a durable protective layer that withstands frequent finger contact while maintaining overall device flexibility.
4Adaptability or versatility
If a foldable cover window is developed, then the adaptability to flexible displays is improved, but the surface hardness and durability are compromised
Solution Approach 1:
The patent utilizes parameter changes by optimizing the chemical composition and molecular structure of the coating layer. Specific parameters including silane content (5-20 wt%), cross-linking density, and film thickness are adjusted to achieve the optimal balance between flexibility for folding and durability for long-term reliability.
Solution Approach 2:
The patent employs composite materials with organic-inorganic hybrid structure that inherently provide both flexibility and durability. The cross-linked network structure maintains integrity during folding while the composite composition ensures resistance to yellowing and degradation over time, enhancing long-term reliability.
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 achieves a cover window with improved reliability and durability, maintaining suitable surface hardness and hardness restoring force, even after external stimulation, and reduces the yellowing phenomenon when exposed to UV radiation over time.
Implementation Method 1
preparing and converting under a catalyst a compound represented by Chemical Formula 1 into a first monomer represented by Chemical Formula 2
Implementation Method 2
applying the coating solution on a base film, and performing drying and curing to form a cured coating solution
Implementation Method 3
performing drying and curing to form a cured coating solution
Data Source
AI summary
A cover window according to an example embodiment of the present invention includes: a base film; and a coating layer positioned on the base film, in which the coating layer is formed through application of a coating solution. The coating solution includes a compound represented by the following Chemical Formula 1.In Chemical Formula 1, R is CH3, R′ is an epoxy group, X, Y, and Z are each independently Si, and Y is 85% to 90% based on a total amount of X, Y and Z.