Photocurable Resin Adhesion for Image Display Devices Under UV Shielding
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Solution Overview
Problem
Conventional methods for manufacturing image display devices using a light-transmitting cured resin layer between a liquid crystal display panel and a light-transmitting cover member face issues with adhesion strength, particularly under heating environments, due to incomplete curing of the photocurable resin composition, which is exacerbated by the presence of a light-shielding layer and requires complex processes involving both photopolymerization and thermal polymerization.
Innovation Solution
A method involving the application of a liquid photocurable resin composition to the light-shielding layer of a light-transmitting cover member, followed by UV irradiation under vacuum or inert gas to achieve a cure rate of 90% or more, both on the surface and throughout the layer, eliminating the need for thermal polymerization and enhancing adhesion strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a photocurable resin composition is applied between a light-shielding layer and an image display member, then adhesion can be achieved, but the light-shielding layer blocks UV rays causing insufficient curing and reduced adhesion strength
Solution Approach 1:
The resin composition is segmented into two distinct functional components: a photocurable resin that cures with UV light to provide initial adhesion, and a thermosetting resin that cures with heat to provide enhanced adhesion strength. This segmentation allows each component to address different aspects of the curing problem independently.
Solution Approach 2:
The invention uses a composite resin composition combining photocurable and thermosetting resins. The photocurable resin provides initial bonding through UV curing, while the thermosetting resin provides additional adhesion strength through thermal curing, creating a multi-functional material that overcomes the limitations of single-resin systems.
2Strength
If both photopolymerization and thermal polymerization processes are applied to cure the resin composition, then adhesion strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the photopolymerization and thermal polymerization processes into a single integrated manufacturing workflow. The resin composition contains both photocurable and thermosetting components that can be cured in sequence using existing equipment, combining the benefits of both curing mechanisms while streamlining the manufacturing process.
Solution Approach 2:
The curing process continues in two stages: first, UV light initiates photopolymerization for immediate adhesion; then, thermal energy completes the curing through thermosetting polymerization. This continuous action ensures complete resin curing and maximum adhesion strength without requiring separate manufacturing lines.
3Reliability
If a thermosetting and photocurable resin composition is used, then adhesion under heating environment is improved, but storage stability decreases
Solution Approach 1:
The resin composition has different functional components with different stability characteristics: the photocurable resin portion remains stable during storage and only reacts when exposed to UV light, while the thermosetting resin portion provides heat resistance when cured. This local differentiation of functionality allows the material to exhibit both storage stability and heating environment reliability.
Solution Approach 2:
The photocurable resin provides preliminary adhesion through UV curing before the thermal curing process. This preliminary action creates an initial bond that holds the components together during storage and handling, while the thermosetting component provides long-term stability under heating conditions.
4Reliability
If the surface of the resin composition layer is cured by light before thermal polymerization, then oxygen inhibition is suppressed, but the structure of the image display device prevents sufficient UV irradiation
Solution Approach 1:
The curing process is made dynamic and adaptable to the device structure. Instead of requiring complete surface curing before thermal processing, the system allows progressive curing: UV light cures the accessible portions of the resin, and thermal energy completes the curing of deeper portions that are shielded by the device structure. This dynamic approach accommodates various device geometries.
Solution Approach 2:
The invention changes the curing parameters from requiring complete UV penetration to using a combination of UV and thermal curing. The dual-curing mechanism allows the process to adapt to different resin thicknesses and device structures, with UV providing surface curing and heat providing deep curing, eliminating the need for perfect UV penetration.
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 method ensures robust adhesion between the light-transmitting cover member and the image display member, maintaining adhesion strength even under heating conditions without the need for thermal polymerization, thereby preventing peeling and ensuring a reliable bond.
Implementation Method 1
irradiating the composition with ultraviolet rays, and curing the composition to form a light-transmitting cured resin layer
Implementation Method 2
irradiating the photocurable resin composition layer with ultraviolet rays under vacuum or an inert gas atmosphere
Data Source
AI summary
A liquid photocurable resin composition not containing a thermal polymerization initiator is applied to a surface of a light-transmitting cover member having a light-shielding layer or a surface of an image display member, irradiated with ultraviolet rays under an atmosphere where the oxygen concentration is significantly decreased and cured, to form a light-transmitting cured resin layer. Subsequently, the image display member and the light-transmitting cover member are stacked through the light-transmitting cured resin layer to manufacture an image display device of the present invention.