Amine-functional curing agents for epoxy coatings
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Solution Overview
Problem
Amine-functional curing agents for epoxy-functional compounds face issues such as skin sensitization, environmental sensitivity, and the formation of 'amine-bloom' due to reactions with water and CO2, leading to adverse film properties and health concerns, especially at low temperatures and high humidity.
Innovation Solution
The development of amine-functional curing agents formed by reacting mono-functional epoxy compounds with amides derived from α-β unsaturated acids or esters, which are stable and resistant to amine bloom, allowing for high solids content coatings with improved color stability and curing rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If amine-functional compounds are used to cure epoxy-functional compounds, then the curing reaction proceeds effectively, but the system becomes sensitive to environmental conditions (humidity and CO2) leading to amine-bloom formation
Solution Approach 1:
The patent applies preliminary action by pre-reacting the amine-functional compound with a carboxylic acid or ester to form an amide bond before the epoxy curing process. This pre-reaction reduces the free amine content that would otherwise react with environmental moisture and CO2, thereby preventing amine-bloom formation while maintaining curing effectiveness through the retained amine groups
Solution Approach 2:
The patent changes the chemical parameter of the curing agent by introducing amide groups through reaction with carboxylic acids or esters. This modification alters the reactivity and environmental stability of the amine groups, reducing their sensitivity to humidity and CO2 while preserving their epoxy-curing capability
2Object-affected harmful factors
If the molecular weight of the amine-functional compound is increased to reduce skin sensitization risk, then safety improves, but the viscosity increases requiring more solvent
Solution Approach 1:
The patent changes the chemical structure parameter by introducing amide groups through reaction with carboxylic acids or esters. This structural modification increases molecular weight and reduces skin sensitization risk while the specific chemistry maintains relatively low viscosity, reducing the need for excessive solvent addition
3Use of energy by moving object
If low temperature curing is performed, then energy consumption decreases, but amine-bloom formation increases due to higher reactivity with water and CO2
Solution Approach 1:
The patent applies preliminary action by pre-forming amide bonds before low-temperature curing. This reduces the population of free amine groups available to react with environmental moisture and CO2 during low-temperature curing, thereby preventing amine-bloom formation while maintaining the energy efficiency of low-temperature processing
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
These agents prevent amine bloom formation, reduce the need for organic solvents, and provide coatings with enhanced color stability and curing efficiency, even at low temperatures and high humidity, while minimizing health and environmental risks.
Implementation Method 1
the amine-functional curing agent can react with water and CO 2 to form carbamate salts
Implementation Method 2
there are fewer amine groups to react with epoxy groups. This has an effect on the network that is formed in the film
Data Source
AI summary
The present invention relates to compounds suitable to use as curing agents for epoxy systems which can be obtained by reacting an amine-functional compound with an a-ß unsaturated acid and/or ester and a mono-functional epoxy compound. The invention further relates to coating compositions comprising these curing agents.