Urethane Acrylate Adhesive for Flexible Display Reliability
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Solution Overview
Problem
Existing adhesive materials for flexible display devices face challenges in maintaining reliability during folding or bending operations due to inadequate shear modulus and peel strength, which can lead to vulnerability under external impacts.
Innovation Solution
A resin composition comprising a urethane (meth)acrylate oligomer derived from a phosphate ester-containing polyol, combined with a (meth)acrylate monomer and photoinitiator, is used to create an adhesive member with improved shear modulus and peel strength through a dual curing process, ensuring reliability in flexible display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesive materials are used in flexible display devices, then the device can be manufactured with basic adhesive functionality, but the adhesive reliability during folding or bending operations deteriorates due to inadequate shear modulus and peel strength
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive resin by incorporating specific urethane (meth)acrylate oligomers with controlled molecular weights (805-955) and phosphate ester-containing polyols with specific structures (Formula 1 where n1 is 3 or 4). This parameter optimization in the resin composition enables the adhesive to achieve both low viscosity for easy application and high shear modulus (1.0×10^3 Pa to 2.0×10^5 Pa at -20°C) and peel strength (800 gf/25 mm or more) for reliable performance during folding operations
Solution Approach 2:
The patent creates a composite adhesive system by combining multiple components: urethane (meth)acrylate oligomer, phosphate ester-containing polyol, (meth)acrylate monomer, and photoinitiator. This composite resin composition synergistically provides both the required low viscosity for easy application and the high mechanical strength properties needed for reliability during folding, resolving the contradiction between ease of application and structural strength
2Reliability
If the adhesive resin is formulated to achieve high shear modulus and peel strength, then the reliability during folding improves, but the viscosity before curing may increase making application difficult
Solution Approach 1:
The patent optimizes the molecular weight parameters of the urethane (meth)acrylate oligomer (805-955) and the structure parameters of the phosphate ester-containing polyol (Formula 1 with n1=3 or 4) to achieve the desired balance. This parameter control ensures the resin composition has low viscosity (5.0-20.0 mPa·s at 25°C) for easy application while the cured product achieves high shear modulus and peel strength for folding reliability
Solution Approach 2:
The patent applies different functional components to different aspects of the adhesive performance: the urethane (meth)acrylate oligomer and phosphate ester-containing polyol provide the structural framework for high strength, while the (meth)acrylate monomer (80-90 wt%) provides the bulk for low viscosity and easy application. This local functional assignment allows simultaneous optimization of both application ease and folding reliability
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 member exhibits a suitable shear modulus of 1.0×10^3 Pa to 2.0×10^5 Pa at -20°C and a 180-degree peel strength of 800 gf/25 mm or more, enhancing the reliability and durability of flexible display devices during folding or bending.
Implementation Method 1
at least one photoinitiator
Data Source
AI summary
A resin composition may include at least one urethane (meth)acrylate oligomer, at least one (meth)acrylate monomer, and at least one photoinitiator. The urethane (meth)acrylate oligomer may include a first urethane (meth)acrylate oligomer derived from a phosphate ester-containing polyol represented by Formula 1, and the first urethane (meth)acrylate oligomer may have a number-average molecular weight of about 805 to about 955. Accordingly, the resin composition may exhibit the characteristics of a low viscosity before being cured, and excellent or suitable shear modulus and peel strength after being cured.