Dual-Curing Epoxy Acrylate Mass for Electronics Sealing
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Solution Overview
Problem
Dual-curing adhesives, particularly those based on acrylates and cyanoacrylates, face issues such as oxygen inhibition, extreme shrinkage, poor temperature resistance, and moderate moisture resistance, limiting their application in industries like electronics, where high mechanical and thermal stability is required.
Innovation Solution
A dual-curing solvent-free single-component mass comprising 30-60% bifunctional epoxy-containing compounds, 5-35% hybrid compounds with isocyanate and radically polymerizable groups, 5-40% latent curing agents, and 0.2-5% photoinitiators, which allows for surface dryness through radical photopolymerization followed by heat curing, achieving mechanical properties comparable to heat-cured epoxy resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If acrylate-based dual-curing adhesives are used, then rapid light curing is achieved, but oxygen inhibition causes surface moisture and poor moisture resistance
Solution Approach 1:
The patent uses a composite system combining epoxy resin (for moisture resistance and mechanical strength) with acrylate groups (for rapid light curing). The epoxy acrylate molecule integrates both chemical systems, allowing simultaneous achievement of fast photopolymerization and excellent moisture/thermal resistance through the epoxy network.
Solution Approach 2:
The patent modifies the chemical composition by incorporating epoxy acrylate with specific epoxy-to-acrylate group ratios (0.5:1 to 2:1), adjusting the curing mechanism from purely radical-based to a hybrid system that eliminates oxygen inhibition while maintaining rapid light curing capability.
2Loss of time
If acrylate adhesives are used for rapid fixation, then handling time is reduced, but extreme shrinkage and poor temperature resistance occur
Solution Approach 1:
The epoxy-acrylate hybrid system combines the rapid curing kinetics of acrylates with the superior thermal stability of epoxy resins, achieving both fast fixation and high temperature resistance (85°C stability in 85/85 testing).
Solution Approach 2:
The patent adjusts the functional group ratio and molecular structure of the epoxy acrylate to control polymerization shrinkage and thermal expansion, reducing extreme shrinkage while maintaining rapid light curing for quick fixation.
3Stability of the object's composition
If cationically dual-curing masses are used, then surface dryness is achieved, but sensitivity to alkaline substrate surfaces inhibits broader application
Solution Approach 1:
The patent changes the curing mechanism from cationic to a free-radical epoxy-acrylate system that is insensitive to substrate pH, achieving surface dryness through complete curing without the limitations of cationic polymerization on alkaline surfaces.
4Strength
If epoxy resins with latent curing agents are heat-cured, then excellent mechanical properties are achieved, but light curing capability is lost
Solution Approach 1:
The patent creates a hybrid epoxy-acrylate system that integrates the excellent mechanical properties of heat-cured epoxy resins with the rapid light curing capability of acrylates, enabling both curing methods to achieve comparable or superior performance.
Solution Approach 2:
The patent modifies the curing agent system to include photoinitiators alongside latent heat-curing agents, transforming the single heat-curing epoxy system into a dual-curing system that maintains mechanical strength while adding light curing versatility.
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 solution enables surface dryness and excellent mechanical properties after light curing, with storage modulus of at least 25,000 Pa, matching the performance of heat-cured epoxy resin masses, while allowing for rapid initial fixation and sealing, suitable for electronics and construction applications.
Implementation Method 1
radical photopolymerization by irradiation with light in the UV-A/VIS range from 315 to 800 nm
Implementation Method 2
heat curing of the masses
Data Source
AI summary
The invention relates to a dual-curing solvent-free single-component mass for the bonding, molding, sealing and coating of substrates, in particular of electronic components. The mass comprises an at least bifunctional epoxy-containing compound; a hybrid compound carrying at least one isocyanate group and, at the same time, at least one radically polymerizable group; a latent curing agent based on nitrogen compounds suitable for crosslinking the epoxy-containing compound by addition reaction; a photoinitiator capable of forming radicals when irradiated with light, and optionally other additives. The mass is characterized in that it is surface dry after light curing by means of radical photopolymerization.