Low Dielectric Optically Clear Adhesive for Foldable Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optically clear adhesives (OCAs) for flexible electronic displays are insufficient in meeting the demands of foldable and durable displays, as they lack the necessary bendability, recoverability, and resistance to environmental factors, which affects touch sensitivity and structural integrity.
Innovation Solution
An assembly layer derived from specific acrylic monomer compositions, including C1-C9 alkyl(meth)acrylate, C10-C24 alkyl(meth)acrylate, hydroxyl (meth)acrylate, non-hydroxy functional polar monomers, and crosslinkers, providing elastic properties, high adhesion, and optical clarity, while minimizing stress and delamination during repeated flexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical optically clear adhesives (OCA) are used to provide durability under environmental exposure and high frequency loading, then adhesion and damping properties are improved, but the adhesive lacks sufficient bendability and recoverability for foldable displays
Solution Approach 1:
The patent modifies the chemical composition parameters of the OCA by incorporating specific ratios of flexible polymer components (such as polyisobutylene and silicone oil) alongside traditional acrylic monomers. This parameter change enables the adhesive to maintain its adhesion and damping properties while gaining the necessary bendability and elastic recovery for foldable display applications.
Solution Approach 2:
The invention creates a composite adhesive material that combines multiple polymer systems (acrylic monomers, polyisobutylene, silicone oil) to achieve properties that cannot be obtained with a single material. This composite structure provides both the durability required for environmental resistance and the flexibility needed for foldable displays.
2Strength
If OCAs with higher dielectric constant are used to improve adhesion, then bonding strength is improved, but touch sensitivity of the display decreases
Solution Approach 1:
The patent carefully controls the dielectric constant parameter of the OCA by adjusting the composition ratios of different polymer components. By maintaining the dielectric constant within a specific range (2.0-4.0), the adhesive achieves sufficient adhesion strength while minimizing interference with the capacitive touch sensor operation, thereby preserving touch sensitivity.
3Reliability
If thicker OCA layers are used to absorb folding-induced stress, then protection of fragile components is improved, but optical clarity and brightness of the display decreases
Solution Approach 1:
The invention changes the mechanical property parameters of the OCA, specifically its elastic modulus and tensile strength, by adjusting the polymer composition. This enables thinner adhesive layers (5-50 micrometers) to achieve the same stress-absorbing capability as thicker layers, thereby maintaining optical clarity and display brightness while still protecting fragile components during folding.
Solution Approach 2:
The patent employs a thin film adhesive structure that provides sufficient mechanical protection through optimized material properties rather than thickness. The flexible polymer composition allows the thin OCA layer to effectively absorb and distribute folding-induced stresses while minimizing optical interference.
4Reliability
If OCAs with high visco-elastic properties are used to provide damping, then durability under loading is improved, but bendability and elastic recovery for folding is reduced
Solution Approach 1:
The invention creates a composite adhesive system that combines materials with different visco-elastic characteristics. The mixture of acrylic monomers, polyisobutylene, and silicone oil produces an adhesive with balanced properties: sufficient damping for durability under high-frequency loading while maintaining the elastic recovery necessary for repeated folding and unfolding cycles.
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 enables flexible devices to withstand significant folding and environmental exposure without delamination or optical defects, maintaining high transparency and adhesion, thus enhancing the durability and performance of flexible displays.
Implementation Method 1
Typical OCAs are visco-elastic in nature and are meant to provide durability under a range of environmental exposure conditions and high frequency loading
Implementation Method 2
a high level of adhesion and some balance of visco-elastic property is maintained to achieve good pressure-sensitive behavior
Data Source
AI summary
The present invention is an assembly layer for a flexible device. The assembly layer is derived from precursors that include about 0 to about 50 wt % C1-C9 alkyl(meth)acrylate, about 40 to about 99 wt % C10-C24 (meth)acrylate, about 0 to about 30 wt % hydroxyl (meth)acrylate, about 0 to about 10 wt % of a non-hydroxy functional polar monomer, and about 0 to about 5 wt % crosslinker.