Solvent-Free Protective Film Adhesive for Bubble-Free OLED Peeling
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Solution Overview
Problem
Conventional protective films for organic light-emitting diodes (OLEDs) face issues with bubble generation and degradation due to solvent use, leading to potential damage and residue on the encapsulation layer during fabrication, and require improvements in peel strength and productivity.
Innovation Solution
A solvent-free surface protective film with an adhesive layer composed of a urethane-based resin, monofunctional (meth)acrylate monomer, crosslinking agent, and photoinitiator, which is photocurable and has a peel strength of 0.5 gf/in to 10 gf/in, preventing bubble formation and enhancing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solvent is used to fabricate the protective film, then the adhesive layer can be formed, but bubbles are generated and leveling degradation occurs during solvent volatilization
Solution Approach 1:
The patent changes the fundamental parameter of the adhesive composition from solvent-based to solvent-free. By using a solvent-free urethane resin composition with photopolymerizable groups, the film is formed without undergoing volatilization processes, thereby eliminating bubble generation and leveling degradation while maintaining proper adhesive properties and surface smoothness
Solution Approach 2:
The patent replaces the thermal/chemical volatilization process with a photopolymerization process. Instead of relying on solvent evaporation to form the adhesive layer, the composition uses photopolymerizable groups that cure upon UV irradiation, substituting the mechanical/thermal process with a chemical photopolymerization process that avoids bubble formation
2Reliability
If conventional protective film is used, then the encapsulation layer can be protected, but peel strength is too high causing damage and residue on the encapsulation layer
Solution Approach 1:
The patent adjusts the peel strength parameter by modifying the adhesive composition to include specific components (urethane resin with photoreactive groups, monofunctional acrylate monomer, crosslinking agent) and controlling the composition ratio. This enables the adhesive layer to achieve optimal peel strength (0.5-10 gf/in) that provides sufficient protection during handling while allowing easy, damage-free removal from the encapsulation layer
Solution Approach 2:
The patent uses a composite adhesive composition combining multiple components: urethane-based resin with photoreactive groups, monofunctional acrylate monomer, crosslinking agent with photoreactive groups, and photoinitiator. This composite formulation creates an adhesive layer with balanced properties that simultaneously ensures reliable bonding during fabrication and enables clean, residue-free removal
3Ease of manufacture
If solvent-based adhesive is used, then the protective film can be formed, but productivity is reduced due to solvent volatilization time
Solution Approach 1:
The patent replaces the time-consuming solvent volatilization process with immediate photopolymerization. The solvent-free composition containing photopolymerizable groups and photoinitiator cures upon UV irradiation, eliminating the waiting time required for solvent evaporation and significantly reducing the fabrication cycle time while maintaining proper film formation
Solution Approach 2:
The patent enables continuous production by eliminating the sequential steps of solvent application followed by volatilization waiting. The photopolymerization process allows immediate curing upon UV exposure, enabling continuous coating and curing operations without interruption or waiting periods, thereby improving manufacturing throughput and productivity
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 prevents bubble generation and degradation of the protective film, ensuring low peel strength and improved productivity without solvent use, thereby protecting the encapsulation layer and maintaining film smoothness.
Implementation Method 1
a urethane-based resin having a photoreactive group at the end or side chain thereof; a crosslinking agent having two or more photoreactive groups at the end thereof; and a photoinitiator
Data Source
AI summary
The present invention provides a surface protective film which includes an adhesive layer on one surface of a substrate film, wherein the adhesive layer is a cured product of a composition containing: a urethane-based resin having a photoreactive group at the end or side chain thereof; a monofunctional (meth)acrylate monomer; a crosslinking agent having two or more photoreactive groups at the end thereof; a peel strength adjusting agent; and a photoinitiator, the composition being solvent-free; and the adhesive layer has peel strength of 0.5 gf/in to 10 gf/in, as measured on glass at a peel angle of 180° and a peel rate of 1.8 m/min.