Photocurable Adhesive Composition for Electronic Paper
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Solution Overview
Problem
Adhesive compositions for electronic paper face challenges in maintaining adhesion and high-temperature reliability due to low compatibility with highly hydrophobic solvents, leading to deterioration in durability and surface energy changes during photocuring.
Innovation Solution
A composition combining thermally curable epoxy resin with a hydroxyl group-containing epoxy copolymer and UV curable epoxy resin, along with a cationic photoinitiator, which maintains hydrophilicity and crosslinking density, ensuring excellent adhesion and chemical resistance to hydrophobic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photocurable adhesive composition is coated onto an upper side of an ink layer prepared using a highly hydrophobic solvent, then the adhesive composition can be bonded to a protective film through photocuring, but the electronic paper exhibits deterioration in high-temperature reliability and durability due to low compatibility between the solvent and the adhesive composition
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive by incorporating specific ratios of epoxy resin (5-50 wt%), polyol (10-80 wt%), and isocyanate (5-80 wt%). This compositional adjustment enables the adhesive to maintain compatibility with highly hydrophobic solvents while preserving high-temperature reliability, directly resolving the contradiction between solvent compatibility and thermal stability
Solution Approach 2:
The patent creates a composite adhesive system by combining multiple components: epoxy resin, polyol, isocyanate, and photoinitiator. This composite formulation synergistically improves both solvent compatibility and high-temperature reliability, where each component contributes specific properties that collectively resolve the contradiction between hydrophobic solvent compatibility and thermal stability
2Strength
If the adhesive composition is coated and bonded through photocuring, then adhesion to the protective film is achieved, but the adhesive composition exhibits differences in surface energy and contact angle between before and after photocuring, resulting in insufficient adhesion
Solution Approach 1:
The patent adjusts the chemical composition parameters, specifically incorporating polyol (10-80 wt%) and isocyanate (5-80 wt%) in controlled ratios. These compositional changes ensure that surface energy remains stable before and after photocuring, maintaining consistent adhesion strength throughout the curing process and eliminating the adhesion deficiency caused by surface energy fluctuations
3Productivity
If the adhesive composition is formulated for photocuring, then curing speed is improved, but surface energy reduction after UV curing occurs, making it difficult to maintain contact angle and surface energy
Solution Approach 1:
The patent optimizes the photoinitiator content (0.1-10 wt%) and adjusts the molecular weight and structure of the polyol and isocyanate components. These parameter changes enable rapid photocuring while minimizing surface energy reduction, as the specific compositional ratios ensure that the cured adhesive maintains stable surface energy and contact angle properties despite the rapid curing process
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 composition maintains high-temperature reliability and chemical resistance to hydrophobic solvents, with minimal change in surface energy and contact angle before and after photocuring, enhancing its durability and performance in electronic materials and paper applications.
Implementation Method 1
a photocurable adhesive composition... is bonded to a protective film through photocuring... including a cationic photoinitiator
Implementation Method 2
a thermally curable epoxy resin formed of a hydroxyl group-containing epoxy copolymer... maintains hydrophilicity and crosslinking density, ensuring excellent adhesion and chemical resistance to hydrophobic solvents
Data Source
AI summary
Provided is an adhesive composition comprising: a thermosetting epoxy resin formed with an epoxy copolymer containing a hydroxyl group; and a UV curable epoxy resin having an epoxy equivalence of 100 g/eq to 500 g/eq.