EVOH Capsule Epoxy Resin Oxygen Barrier
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Solution Overview
Problem
Current curable adhesive compositions fail to achieve high adhesive strength immediately after application, exhibit excellent flexibility, and provide adequate oxygen barrier performance, especially for sealing flexible substrates in electronic devices and other applications where oxygen permeation control is crucial.
Innovation Solution
A curable composition comprising bisphenol F epoxy resin and ethylene-vinyl alcohol (EVOH) copolymer capsules, dispersed in a specific weight ratio, which improves oxygen transmission rate and physical properties such as toughness and durability, along with the inclusion of rubber-modified epoxy resin and epoxy acrylate components for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional curable adhesive compositions are used, then they can be applied by melt or liquid coating and cured by heat or radiation, but they fail to achieve adequate oxygen barrier performance
Solution Approach 1:
The patent combines EVOH copolymer (providing oxygen barrier properties) with curable adhesive composition (providing bonding and flexibility). This composite structure allows the sealant to simultaneously achieve excellent oxygen barrier performance and maintain adaptability for flexible substrate sealing applications.
Solution Approach 2:
The EVOH copolymer is dispersed as particles within the adhesive composition, creating localized regions of high oxygen barrier performance within the bulk material. This allows the sealant to provide oxygen barrier function at specific locations while maintaining overall flexibility and adaptability.
2Strength
If high adhesive strength is achieved immediately after application, then bond strength is improved, but flexibility and durability may be compromised
Solution Approach 1:
The patent uses a curable adhesive composition that transitions from a flexible liquid/gel state during application to a crosslinked network structure after curing. This parameter change allows high adhesive strength to be achieved immediately upon application while the curing process subsequently locks in flexibility and durability through controlled crosslinking density.
Solution Approach 2:
The combination of EVOH particles with the curable adhesive matrix creates a composite where the particles provide structural reinforcement and barrier properties, while the polymer matrix provides flexibility. After curing, the crosslinked network maintains both strength and flexibility through the synergistic interaction of these components.
3Reliability
If oxygen barrier performance is improved through material selection, then oxygen transmission rate is reduced, but the composition complexity increases
Solution Approach 1:
The EVOH copolymer is dispersed as particles with controlled morphology within the adhesive composition. This particle dispersion approach provides oxygen barrier performance through the tortuous path effect created by the particles, achieving effective oxygen blocking without requiring complex multilayer structures or extensive compositional modifications.
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 rapid curing, high adhesive strength, excellent flexibility, and improved oxygen barrier performance, making it suitable for applications requiring durable seals in sensitive devices and materials.
Implementation Method 1
improved oxygen barrier properties... improved oxygen transmission rate... oxygen permeation control is crucial
Implementation Method 2
A large number of curable adhesive compositions is based on a ring-opening reaction of an epoxy resin, i.e. these curable adhesive compositions obtain a high bond strength through a ring-opening polymerization of an epoxy group
Data Source
AI summary
Curable polymeric compositions with improved barrier property to oxygen suitable to be used on flexible substrates containing a bisphenol F epoxy resin, at least an epoxy acrylate component and at least a rubber modified bisphenol and further comprising EVOH capsules or beads dispersed therein. The polymeric compositions are applicable either by a melt or liquid coating technique and undergo curing upon exposure to heat, showing viscoelastic properties and suitable to provide a cured product having high durability.