Epoxy Syrup Adhesive Water Vapor Barrier
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Solution Overview
Problem
Current barrier adhesives for encapsulating organic electronics face limitations in achieving high epoxy content while maintaining pressure-sensitivity and low halogen content, as epoxy resins are either liquid and difficult to formulate into tapes or require refrigerated transport due to crosslinking reactions.
Innovation Solution
A storable, pressure-sensitive barrier adhesive with high epoxy content (>50%) is achieved by using a combination of bisepoxy monomers and high molecular weight uncrosslinked polyepoxies, which maintains good water vapor barrier properties and pressure-sensitivity, with viscosities adjusted through controlled polymerization and initiator scavenger use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid epoxy adhesives are used to achieve good water vapour barrier properties, then barrier performance increases with epoxy proportion, but pressure-sensitive properties decrease and eventually disappear with increasing epoxy proportion
Solution Approach 1:
The patent changes the physical state parameter of epoxy from liquid to semi-solid gel form through controlled polymerization. This parameter change allows the epoxy to maintain high viscosity and pressure-sensitive properties while achieving high epoxy content (>50%) for superior water vapour barrier performance. The gel form prevents the epoxy from being completely liquid, thus preserving tape integrity.
Solution Approach 2:
The patent creates a composite adhesive system combining polymer matrix with high proportions of epoxy resin in gel form. This composite structure integrates the barrier properties of epoxy with the pressure-sensitive characteristics of the polymer-tackifier system, resolving the contradiction between high epoxy content and pressure-sensitivity.
2Length of moving object
If epichlorohydrin-based epoxy resins are used to adjust viscosity, then viscosity increases, but halogen content increases which is not tolerated in electronics industry
Solution Approach 1:
The patent extracts the halogen component (epichlorohydrin) from the epoxy system and replaces it with halogen-free alternatives. This extraction eliminates the harmful halogen content while maintaining the desired viscosity characteristics through the gel-forming polymerization process.
Solution Approach 2:
The patent replaces problematic epichlorohydrin-based epoxies with halogen-free epoxy resins that may have different handling characteristics but eliminate long-term environmental and safety concerns associated with halogen content in electronics applications.
3Length of moving object
If b-staged epoxy systems are used to increase viscosity, then epoxy is no longer liquid, but refrigerated transport is required to prevent complete crosslinking
Solution Approach 1:
The patent applies partial polymerization to achieve gel form without complete crosslinking. This partial action (incipient polymerization) provides sufficient viscosity increase and pressure-sensitivity while avoiding the need for refrigerated transport that would be required for heavily pre-crosslinked b-staged systems.
Solution Approach 2:
The patent controls the degree of polymerization parameter to achieve optimal gel state. By carefully adjusting the extent of polymerization, the epoxy achieves adequate viscosity and pressure-sensitive properties without requiring refrigerated storage, simplifying manufacturing and distribution.
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 resulting adhesive exhibits high viscosity, ease of handling, and effective water vapor barrier properties, allowing for encapsulation of organic electronics with improved lag time and adhesive strength, while minimizing halogen content.
Implementation Method 1
incorporating high molecular weight uncrosslinked polyepoxies, in particular polymerization products of incipient polymerization of bisepoxy monomers
Implementation Method 2
adhesive having water vapour barrier properties comprising an adhesive base composed of at least one epoxy syrup, at least one elastomer, at least one initiator
Data Source
AI summary
An adhesive having water vapor barrier properties, comprising an adhesive base comprised ofat least one epoxy syrupat least one elastomerat least one initiatoroptionally at least one tackifier resin andoptionally at least one further reactive resin andoptionally a solvent,wherein the adhesive base without solvent has a water vapor permeation rate after activation of the reactive resin component of less than 100 g/m2d, preferably of less than 60 g/m2d, in particular less than 30 g/m2d, wherein the epoxy syrup comprises bisepoxy monomers and high molecular weight uncrosslinked polyepoxies produced therefrom, exhibits good barrier properties and is also sufficiently pressure sensitive to achieve easy handleability.