UV Cured Adhesive with Varying Conversion Rates for Foldable Displays
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Solution Overview
Problem
Flexible display devices face challenges in maintaining adhesive strength and flexibility when folded, leading to potential failure due to uneven curing of ultraviolet curable resins in adhesive members.
Innovation Solution
The use of ultraviolet curable resins with varying conversion rates in different regions of the adhesive members, specifically a lower conversion rate in the folding region and a higher conversion rate in the peripheral region, ensures flexibility and adhesive strength, preventing damage during folding and unfolding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ultraviolet curable resin is used in adhesive members to attach outer members to the flexible display panel, then adhesive strength is improved, but the adhesive member becomes rigid and cannot be repeatedly folded without failure
Solution Approach 1:
The adhesive member is divided into different regions with different ultraviolet curable resin conversion rates: a first region (folding area) with 50-80% conversion rate maintaining flexibility, and a second region (peripheral area) with 85-100% conversion rate providing strong adhesion. This local differentiation resolves the contradiction between adhesion strength and foldability.
Solution Approach 2:
The conversion rate of ultraviolet curable resin is changed as a key parameter to control the properties of the adhesive member. By adjusting the conversion rate from 50-80% in folding regions to 85-100% in peripheral regions, the adhesive member achieves both flexibility for repeated folding and sufficient adhesive strength for reliable attachment.
2Reliability
If the ultraviolet curable resin is fully cured to maximize adhesive strength, then bonding reliability is improved, but the adhesive member loses flexibility and cannot withstand repeated folding
Solution Approach 1:
Different regions of the adhesive member are assigned different curing degrees: the folding region maintains 50-80% conversion for flexibility, while the peripheral region achieves 85-100% conversion for reliable bonding. This spatial differentiation of quality resolves the contradiction between bonding reliability and flexibility.
Solution Approach 2:
The adhesive member is segmented into functionally distinct regions based on their requirements: a folding region requiring flexibility and a peripheral region requiring strong adhesion. This segmentation allows each region to be optimized independently for its specific function.
3Adaptability or versatility
If the adhesive member is made flexible to allow repeated folding, then foldability is improved, but adhesive strength decreases leading to potential failure
Solution Approach 1:
The adhesive member exhibits local quality differentiation where the folding region has lower resin conversion (50-80%) for flexibility, while the peripheral region has higher conversion (85-100%) for adhesive strength. This resolves the contradiction between foldability and adhesive strength.
Solution Approach 2:
The ultraviolet curable resin conversion rate parameter is strategically varied across different regions: reduced to 50-80% in folding areas to maintain flexibility, and increased to 85-100% in peripheral areas to ensure strong adhesion, thereby achieving both foldability and adhesive strength.
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
This approach maintains the adhesive strength and flexibility of the flexible display device, allowing it to be repeatedly folded and unfolded without failure, ensuring continuous operation and image display without discontinuity.
Implementation Method 1
The first adhesive member includes an ultraviolet curable resin. The first adhesive member includes first and second regions respectively corresponding to the folding and peripheral regions. The ultraviolet curable resin of the first region has a conversion rate lower than a conversion rate of the ultraviolet curable resin of the second region.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A flexible display device includes a flexible display panel, a first outer member disposed on a surface of the flexible display panel, and a first adhesive member attaching the first outer member to the flexible display panel. The first adhesive member includes an ultraviolet curable resin. A conversion rate of the ultraviolet curable resin in a region of the first adhesive member corresponding to a folding region of the flexible display panel is lower than a conversion rate of other regions adjacent thereto.