Foldable Display Protective Layer Adhesive With UV-Reversible Bonding
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Solution Overview
Problem
Existing display devices, particularly foldable and rollable devices, face challenges in maintaining adhesive strength and ease of reworking the protective layer when it is damaged, which affects folding properties and user convenience.
Innovation Solution
Incorporation of a polymer compound with crosslinking parts that form and separate through Diels-Alder and Retro-Diels-Alder reactions using specific UV wavelengths to control adhesive strength, allowing for reduced adhesive strength in selected areas for improved reworkability and folding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective layer is applied to protect the display surface, then the display surface is protected, but the protective layer cannot be easily removed when damaged
Solution Approach 1:
The adhesive layer transitions from a static bonding state to a dynamic reversible state through light irradiation. The adhesive bonds the protective layer to the display surface under normal conditions, but upon exposure to specific wavelength light, the bonding becomes reversible allowing easy removal. This dynamic behavior resolves the contradiction between maintaining strong protection and enabling easy repair.
Solution Approach 2:
The adhesive properties of the adhesive layer are changed by irradiating with light of a specific wavelength. The adhesive transitions between bonded and debonded states based on light exposure, allowing the same adhesive layer to provide both strong adhesion for protection and easy release for repair, thus resolving the contradiction between reliability and ease of repair.
2Strength
If the adhesive strength is increased to secure the protective layer, then the protective layer is firmly attached, but the adhesive layer experiences high stress in folding regions
Solution Approach 1:
The adhesive layer exhibits different bonding characteristics in different regions based on light exposure. The non-folded region maintains strong adhesive bonding to secure the protective layer, while the folded region can be selectively debonded by light irradiation to reduce stress. This local differentiation of adhesive properties resolves the contradiction between overall adhesion strength and localized stress reduction.
Solution Approach 2:
The adhesive layer is functionally segmented into a non-folded region and a folded region with different bonding states. The non-folded region provides strong adhesion while the folded region allows stress relief through reversible debonding. This segmentation enables the adhesive layer to simultaneously provide strong attachment and stress reduction in different areas.
3Ease of operation
If the adhesive strength is reduced in folding regions to improve folding properties, then folding performance is enhanced, but the protective layer becomes loose in those areas
Solution Approach 1:
The adhesive layer in the folded region transitions from a permanently weak state to a dynamically controllable state. By using light irradiation, the adhesive can be switched between bonded and debonded states, allowing the protective layer to be firmly attached when needed and easily released to improve folding performance, thus resolving the contradiction between attachment reliability and folding ease.
Solution Approach 2:
Light acts as an intermediary to control the adhesive bonding in the folded region. The light irradiation triggers the reversible bonding mechanism, allowing external control over the adhesive strength. This enables the system to achieve both good folding performance (when debonded) and reliable attachment (when bonded) in the folded region.
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
Enables easy removal and reworking of protective layers using UV exposure, enhancing user convenience and folding performance by adjusting adhesive strength as needed.
Implementation Method 1
the multiple crosslinking parts form multiple crosslinking bonds between the multiple polymer main chains through Diels-Alder reaction
Implementation Method 2
the multiple crosslinking bonds are to be separated through Retro-Diels-Alder reaction
Implementation Method 3
the photodimer may undergo photolysis by exposing to second ultraviolet rays with a wavelength of about 280 nm or less
Data Source
AI summary
A display device of an embodiment includes a display module, a window disposed on the upper side of the display module, a protective layer disposed on the upper side of the window, a housing disposed on the lower side of the display module, and a protective layer adhesive layer disposed between the window and the protective layer, wherein the protective layer adhesive layer includes a polymer compound including multiple polymer main chains and multiple crosslinking parts, the crosslinking parts form multiple crosslinking bonds between the polymer main chains through Diels-Alder reaction, and the crosslinking bonds are separated through Retro-Diels-Alder reaction, thereby showing easy reworkability and excellent or suitable mechanical properties.