Light-Debondable Pressure Sensitive Adhesive for OLED Glass
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Solution Overview
Problem
Existing pressure-sensitive adhesives used in OLED manufacturing are difficult to remove from glass substrates without damaging the OLED stack, as they require high stress and often leave residue.
Innovation Solution
A light radiation debondable pressure-sensitive adhesive is developed, comprising a polyurethane polymer, a multifunctional (meth)acrylate oligomer, and a photoinitiator. This adhesive exhibits strong initial bonding to both film substrates and glass, but upon exposure to light radiation, its adhesion to glass decreases significantly, allowing for clean removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional pressure-sensitive adhesives are formulated to provide strong holding power (greater than 30 oz./in adhesion to paper), then strong initial bonding is achieved, but the adhesive becomes difficult to remove without damaging the substrate
Solution Approach 1:
The adhesive's bonding characteristics are made dynamic through light irradiation. The adhesive transitions from a high-bonding state during assembly to a low-bonding state during removal, allowing the same adhesive to provide both strong initial bonding and easy removal without damage
Solution Approach 2:
The adhesive's chemical structure is modified by incorporating photodegradable groups that change the adhesive's properties upon light exposure. This parameter change enables the adhesive to switch between strong bonding and easy removal states, resolving the contradiction between initial bond strength and removal ease
2Ease of operation
If stretch releasing adhesive tapes are used to achieve clean removal and no surface damage, then removal ease is improved, but the adhesive requires a pull tab to initiate stretching and applies relatively high stress during removal
Solution Approach 1:
The pull tab component is extracted and eliminated from the adhesive system. The adhesive itself is modified to enable self-initiated clean removal through light irradiation, removing the need for external mechanical assistance while maintaining removal cleanliness
Solution Approach 2:
The mechanical stretching mechanism required by conventional stretch-releasing tapes is replaced with a photochemical mechanism. Light irradiation triggers the adhesive's debonding process, substituting mechanical initiation with optical activation and eliminating the need for pull tabs
3Strength
If optically clear adhesives (OCAs) are used to bond film substrates to glass during OLED manufacturing, then initial bonding strength is improved, but the adhesive becomes difficult to remove from glass without damaging the OLED stack
Solution Approach 1:
The adhesive provides strong bonding during OLED assembly, then transitions to a low-bonding state upon light irradiation during removal. This dynamic behavior allows the same adhesive to protect the OLED stack during both assembly and removal processes by controlling bond strength at different stages
Solution Approach 2:
The light irradiation that would normally strengthen the adhesive bond is converted into a beneficial debonding trigger. The same optical energy that could potentially harm the OLED during processing is used to initiate clean removal, converting a potential harmful factor into a useful function
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 maintains strong bonding to film substrates after light radiation exposure, while reducing adhesion to glass by at least 20%, enabling easy and clean removal without damaging the OLED stack.
Implementation Method 1
an adhesive composition comprising a polyurethane polymer, a multifunctional (meth)acrylate oligomer, and a photoinitiator
Implementation Method 2
The adhesive maintains strong bonding to film substrates after light radiation exposure, while reducing adhesion to glass by at least 20%
Data Source
AI summary
The present invention is a pressure sensitive adhesive including a polyurethane polymer comprising a reaction product of an isocyanate, a (meth) acrylate-containing alcohol having at least one (meth)acrylate group and at least one alcohol group, and a polyol component having a defined solubility parameter of less than about 10; an oligomer comprising a multifunctional (meth)acrylate; and a photoinitiator. A peel adhesion of the pressure sensitive adhesive to glass decreases at least about 20% after being exposed to light radiation.