Latent-Cure Epoxy-Urethane Composition for Long Workability
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Solution Overview
Problem
Existing curable compositions require multiple components that react at ambient or slightly thermal conditions, limiting their application and storage stability, and there is a need for compositions that can be easily applied and remain workable for extended periods before curing.
Innovation Solution
A one-component curable composition comprising an isocyanate-functional prepolymer, an epoxy-containing component, and a latent curing agent that reacts upon exposure to an external energy source, allowing for a transition from an uncured to a partially cured state when activated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple components are used in curable compositions, then reactivity and curing speed are improved, but storage stability and ease of application are worsened
Solution Approach 1:
The curing agent is segmented into two forms: a latent curing agent that remains dormant during storage and application, and a solid curing agent that activates upon phase change. This segmentation allows the composition to remain stable during storage while achieving rapid curing when needed.
Solution Approach 2:
The invention utilizes parameter changes by controlling the phase state of the curing agent. The solid curing agent transitions to liquid phase upon heating or dissolution, activating its curing function. This parameter change enables the composition to switch between stable storage state and active curing state.
2Productivity
If curable compositions react readily at ambient conditions, then curing efficiency is improved, but storage stability and workability are worsened
Solution Approach 1:
The latent curing agent is prepared in advance in a dormant state that prevents premature reaction. The composition can be applied and worked with for extended periods without curing, then curing is initiated by adding the solid curing agent or applying external energy to activate the latent agent.
Solution Approach 2:
The latent curing agent acts as an intermediary that bridges the gap between storage stability and curing efficiency. It remains inactive during storage and application, then activates to provide rapid curing when triggered by the solid curing agent or external energy.
3Ease of operation
If a one-component composition is used, then ease of application and storage stability are improved, but curing control and adaptability are worsened
Solution Approach 1:
The invention introduces dynamics into the one-component system by incorporating a solid curing agent that can be added at different stages or a latent curing agent that can be activated by external energy. This allows the composition to adapt to different application requirements while maintaining ease of use.
Solution Approach 2:
The curable composition achieves multi-functionality by combining an isocyanate-functional prepolymer, epoxy-containing component, and either latent or solid curing agent. This universal formulation can be used for coating, sealing, bonding, or composite fabrication depending on the specific application and curing conditions.
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 maintains workability for extended periods and efficiently cures upon activation, providing strong adhesion and stability in various applications.
Implementation Method 1
a latent curing agent having an ability to react with at least one of the isocyanate-functional prepolymer and the epoxy-containing component upon exposure to an external energy source
Implementation Method 2
upon exposure to an external energy source
Data Source
AI summary
The present invention is directed to a curable composition including: an isocyanate-functional prepolymer; an epoxy-containing component present in an amount of at least 10 percent by weight of the composition; and a latent curing agent having an ability to react with at least one of the isocyanate-functional prepolymer and the epoxy-containing component upon exposure to an external energy source. The present invention is also directed to methods of making the compositions, methods of coating a substrate, methods of adhering substrates and coated substrates.