Low Tg Adhesive for Foldable Displays
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Solution Overview
Problem
Foldable displays face challenges in maintaining reliability and stability during transformation, as existing adhesives can lead to damage due to high storage modulus and increased impact transfer rates, resulting in issues like delamination, bubbles, and cracks during the folding process.
Innovation Solution
An adhesive composition for foldable displays is developed, using a thermocurable resin with a glass transition temperature of −70° C. or lower, incorporating a compound with N or O and unshared electron pairs, which lowers storage modulus and increases dielectric polarizability, thereby reducing the risk of damage and improving bending reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesive is used in foldable display, then adhesive strength is maintained, but storage modulus becomes too high causing damage during transformation
Solution Approach 1:
The patent changes the glass transition temperature parameter of the adhesive resin to -70°C or lower, which fundamentally alters the storage modulus characteristics. This parameter change allows the adhesive to maintain strength while reducing stiffness during folding transformations, preventing damage to display components.
Solution Approach 2:
The patent uses a composite adhesive system comprising a thermocurable resin with specific molecular structure (including N or O atoms with unshared electron pairs) combined with a crosslinking agent. This composite material achieves both high adhesive strength and low storage modulus, resolving the contradiction between strength and folding reliability.
2Strength
If adhesive with high storage modulus is used, then bond strength is sufficient, but impact transfer rate increases causing delamination and cracks
Solution Approach 1:
By changing the glass transition temperature to -70°C or lower, the patent reduces the storage modulus of the adhesive. This parameter change decreases the adhesive's stiffness, thereby reducing impact transfer rate while maintaining bond strength, preventing delamination and cracks during folding.
Solution Approach 2:
The low storage modulus adhesive acts as a cushioning layer that absorbs and dissipates impact forces before they can propagate to the display components. This beforehand cushioning prevents damage during folding transformations while maintaining adequate bond strength.
3Reliability
If thermocurable resin with low glass transition temperature is used, then storage modulus is reduced improving folding reliability, but dielectric constant decreases affecting touch resolution
Solution Approach 1:
The patent uses a composite system of thermocurable resin with specific polar groups (N or O with unshared electron pairs) and crosslinking agent. This composite achieves both low storage modulus (for folding reliability) and high dielectric constant (for touch resolution) by leveraging the polar characteristics of the resin molecules.
Solution Approach 2:
The patent introduces polar groups (N or O atoms with unshared electron pairs) at specific molecular locations in the resin structure. These localized polar regions increase dielectric constant and improve touch resolution while the overall low glass transition temperature maintains low storage modulus for folding 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 adhesive composition effectively reduces storage modulus and impact transfer rates, enhancing the reliability and durability of foldable displays by forming a dipole arrangement that increases dielectric constant and reduces the likelihood of delamination and cracks, while maintaining high touch resolution and response rates.
Implementation Method 1
the thermocurable resin has a glass transition temperature of −70° C. or lower
Implementation Method 2
the compound including at least one N or O; and at least one unshared electron pair in the molecule becomes polar by a dipole moment, and a dipole moment is generated in the adhesive by applying an electric field to the polymer including the compound having polarity
Implementation Method 3
dielectric polarizability increases resulting in an increase in the dielectric constant
Data Source
AI summary
The present application provides an adhesive composition for a foldable display including a thermocurable resin; and a crosslinking agent, wherein the thermocurable resin includes a unit derived from a compound including at least one N or O; and at least one unshared electron pair in the molecule, and the thermocurable resin has a glass transition temperature of −70° C. or lower, an adhesive film using the same, and a foldable display including the same.