Curable Adhesive Composition for High Pluck Adhesion
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Solution Overview
Problem
Optically clear adhesives used in optical displays face challenges with adhesion, particularly in achieving high pluck adhesion values, which are essential for reliable bonding in applications like LCDs and mobile devices.
Innovation Solution
A curable adhesive composition comprising a first oligomer with (meth)acrylate ester monomer units, hydroxyl-functional monomer units, and polymerizable groups, combined with a second component containing C2-C4 alkylene oxide repeat units and polymerizable terminal groups, along with a diluent monomer component, to enhance adhesion properties and maintain optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional liquid optically clear adhesives are used, then optical clarity is maintained, but adhesion strength (pluck adhesion) is insufficient
Solution Approach 1:
The patent employs a composite adhesive system combining multiple components: a first oligomer with hydroxyl-functional monomer units, a second oligomer with carboxyl-functional monomer units, and a diluent monomer. This composite formulation creates synergistic interactions between components to achieve both high pluck adhesion (≥80 N/cm²) and optical clarity, resolving the contradiction between adhesion strength and bonding reliability
Solution Approach 2:
The patent systematically adjusts compositional parameters including the weight ratios of oligomers to diluent (0.9:0.1 to 1:4), molecular weights of oligomers (500-50,000), and functional group concentrations. These parameter optimizations enable the adhesive to achieve peak pluck adhesion values (150-200 N/cm²) while maintaining optical transparency and delamination resistance
2Strength
If adhesive composition is optimized for high pluck adhesion, then bonding strength improves, but optical clarity may deteriorate
Solution Approach 1:
The patent introduces functional monomer units with specific local properties: hydroxyl-functional units (e.g., hydroxyethyl methacrylate) for adhesion enhancement and carboxyl-functional units (e.g., carboxyl-terminated polybutadiene) for complementary bonding. These localized functional groups are distributed within the oligomer structure to provide targeted adhesion promotion without compromising bulk optical clarity
Solution Approach 2:
The patent uses diluent monomers that replicate the optical properties of the cured adhesive matrix. The diluent (e.g., cyclohexyl methacrylate or lauryl methacrylate) has refractive index and transparency characteristics matched to the polymer network, ensuring that high concentrations (up to 90 wt%) do not degrade optical clarity even as adhesion performance is maximized
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 composition achieves pluck adhesion of at least 80 N/cm², with some embodiments reaching up to 200 N/cm², while maintaining optical clarity and resistance to delamination, thus addressing the adhesion challenges in optically clear adhesive applications.
Implementation Method 1
a first oligomer comprising polymerizable groups selected from pendent (meth)acrylate groups or terminal aryl ketone photoinitiator groups
Data Source
AI summary
The disclosure describes a curable composition comprising a first oligomer having a plurality of polymerizable groups; a second component comprising alkylene oxide repeat units and terminal polymerizable groups, a solvent monomer component; and a photoinitiator. The curable composition may be used as an adhesive in optical applications.