Waterborne Amine Curing Agent for Epoxy Coatings
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Solution Overview
Problem
Waterborne epoxy coating systems face issues with poor humidity resistance and short pot life, leading to adhesion loss and early corrosion failure in metal coatings, and require high amine hydrogen equivalent weight (AHEW) levels, limiting their industrial applications.
Innovation Solution
A waterborne amine curing agent is developed through a multi-step process involving a polyamine-polyepoxide adduct reaction, where a first polyamine reacts with a first polyepoxide, followed by urea or formaldehyde, and then a second polyepoxide, and is end-capped with a monoepoxide, improving water solubility and reducing primary amine content, resulting in a curing agent with a lower AHEW and enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional waterborne epoxy coating systems are used, then VOC emissions are reduced, but humidity resistance deteriorates and adhesion is lost
Solution Approach 1:
The patent modifies the chemical composition parameters of the curing agent by using a polyamine-epoxy adduct with specific amine hydrogen equivalent weight (AHEW) ranges (80-400, preferably 100-250), and controlling the ratio of polyepoxide to polyamine (0.5-2.0). These parameter changes enable the waterborne system to achieve both low VOC emissions and improved humidity resistance.
Solution Approach 2:
The invention creates a composite curing agent system by combining polyamine-epoxy adducts with specific molecular structures and properties. The adducts are formed by reacting polyamines with polyepoxides in controlled ratios, creating a composite material that maintains water solubility while providing enhanced humidity resistance and adhesion properties.
2Reliability
If conventional waterborne curing agents are used, then adhesion is maintained, but pot life becomes too short for industrial applications
Solution Approach 1:
The patent adjusts the AHEW parameter of the curing agent to specific ranges (80-400, preferably 100-250) and controls the epoxy to amine ratio (0.5-2.0). These parameter modifications slow the curing reaction kinetics, extending pot life to 4-24 hours while preserving adhesion properties through the controlled molecular structure of the polyamine-epoxy adduct.
3Ease of operation
If conventional waterborne epoxy systems are used, then application is simplified, but corrosion failure occurs early due to poor humidity resistance
Solution Approach 1:
The invention modifies the chemical parameters of the curing agent, specifically the AHEW (80-400) and molecular structure of the polyamine-epoxy adduct. These changes create a coating system that forms more resistant crosslinked networks, preventing moisture penetration and corrosion while maintaining the waterborne application advantages.
4Ease of manufacture
If high AHEW curing agents are used in waterborne systems, then formulation is simplified, but use level becomes too high for practical applications
Solution Approach 1:
The patent optimizes the AHEW parameter to specific ranges (80-400, preferably 100-250) and controls the epoxy to amine ratio (0.5-2.0). This parameter optimization achieves a balance between formulation simplicity and practical use levels, enabling effective curing at lower concentrations while maintaining waterborne system advantages.
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 provides improved humidity resistance, extended pot life, and enhanced adhesion and flexibility, enabling the use of waterborne epoxy coatings in industrial applications with superior performance compared to commercial systems.
Implementation Method 1
the reaction of a first polyamine containing primary amine functionality and a first polyepoxide having an epoxide equivalent weight (EEW) of 130 to about 500 in a ratio of moles of polyamine per equivalents of polyepoxide sufficient to provide an amine terminated intermediate (a) comprising an adduct
Implementation Method 2
intermediate (a) being then reacted with urea or formaldehyde to provide an amine terminated intermediate (b)
Implementation Method 3
intermediate (b) being then reacted with a second polyepoxide having an EEW of 200 to about 1000 to provide an amine terminated intermediate (c)
Implementation Method 4
intermediate (c) being end capped with a monoepoxide composition comprising an aromatic glycidyl ether or an alkyl substituted aromatic glycidyl ether, or a combination of both, to form a polyamine-polyepoxide adduct
Data Source
Figure 1
AI summary
The present invention discloses a waterborne amine curing agent, process of making such curing agent, and curable amine-epoxy compositions. The curing agent comprises the product of the reaction of a first polyamine containing primary amine functionality and a first polyepoxide in a ratio of moles of polyamine per equivalents of polyepoxide sufficient to provide an amine terminated intermediate (a) comprising an adduct of about two moles of polyamine and one mole polyepoxide, intermediate (a) being then reacted with urea or formaldehyde to provide an amine terminated intermediate (b), intermediate (b) being then reacted with a second polyepoxide to provide an amine terminated intermediate (c), intermediate (c) being end capped with a monoepoxide composition comprising an aromatic glycidyl ether or an alkyl substituted aromatic glycidyl ether, or a combination of both, to form a polyamine-polyepoxide adduct, and contacting the polyamine-polyepoxide adduct with a second polyamine having two or more active amine hydrogens.