Benzylated Polyalkylene Polyamine Curing Agents for Epoxy Coatings
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Solution Overview
Problem
Amine-epoxy coatings based on neat polyalkylene polyamines like ethylenediamine homologues suffer from smoking, fuming, blush, carbamation, and carbonation due to incompatibility with epoxy resins, leading to surface defects and adhesion issues, especially at low temperatures, where phase separation and amine migration occur.
Innovation Solution
The development of benzylated polyalkylene polyamine curing agent compositions with at least three nitrogen atoms and one benzyl group, combined with multifunctional amines, which improve compatibility with epoxy resins, reduce smoking and fuming, and eliminate free amines, thereby enhancing the handling properties and appearance of the coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If neat polyalkylene polyamines are used as curing agents for epoxy resins, then the curing reaction proceeds effectively, but smoking, fuming, blush, carbamation, and carbonation occur due to high amine vapor pressure and incompatibility
Solution Approach 1:
The patent modifies the chemical structure of polyalkylene polyamines by introducing benzyl groups through alkylation, changing physical parameters such as vapor pressure and compatibility. This structural modification reduces amine vapor pressure and improves compatibility with epoxy resins, thereby eliminating smoking and fuming while maintaining curing effectiveness
Solution Approach 2:
The patent creates a composite curing agent system by combining benzylated polyalkylene polyamines with epoxy resins, forming a chemically compatible mixture that prevents phase separation. This composite approach ensures uniform distribution and reaction, eliminating the harmful surface defects associated with incompatible neat polyamines
2Ease of manufacture
If neat polyalkylene polyamines are used as curing agents, then the curing process is simple, but phase separation occurs leading to blush, carbamation, and carbonation surface defects
Solution Approach 1:
The patent changes the chemical composition parameters of the curing agent by introducing benzyl groups, which fundamentally alters compatibility parameters. This modification prevents phase separation and the associated surface defects (blush, carbamation, carbonation) while maintaining a similarly simple application process
Solution Approach 2:
The patent takes the inherent reactivity of polyamines that causes compatibility issues and transforms it by chemical modification. The benzyl groups reduce polarity and improve compatibility, converting the harmful phase separation tendency into beneficial homogeneous mixing and uniform curing
3Use of energy by stationary object
If coatings are applied and cured at low temperature, then energy consumption is reduced, but amine-epoxy incompatibility is exacerbated leading to extended setting time and increased amine migration
Solution Approach 1:
The patent changes the chemical structure parameters of the curing agent to improve low-temperature reactivity. The benzylated structure maintains adequate reaction kinetics at lower temperatures by reducing the activation energy barrier, thereby shortening setting time while maintaining energy efficiency
Solution Approach 2:
The patent introduces localized benzyl groups at specific positions on the polyamine structure, creating regions of improved compatibility without sacrificing the reactive amine functionality. This localized modification enables better low-temperature performance while maintaining overall curing effectiveness
4Manufacturing precision
If ripening time is applied to clear coats to achieve high gloss and clarity, then coating appearance is improved, but production time is extended
Solution Approach 1:
The patent performs preliminary chemical modification of the curing agent structure before application. The pre-introduced benzyl groups ensure compatibility and prevent phase separation during the curing process itself, eliminating the need for post-application ripening time to achieve gloss and clarity
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 benzylated polyalkylene polyamine compositions demonstrate improved compatibility with epoxy resins, eliminating the need for ripening time, reducing surface defects, and enhancing the clarity and gloss of coatings, while maintaining single-phase uniformity and reducing VOCs, thus addressing the issues of smoking, blush, and carbamation.
Implementation Method 1
curing, harden, and/or crosslink an epoxy resin
Implementation Method 2
the reductive amination of a benzaldehyde compound with a polyalkylene polyamine
Data Source
AI summary
The present invention provides curing agent compositions comprising benzylated polyalkylene polyamine compounds. Amine-epoxy compositions and articles produced from these amine-epoxy compositions are also disclosed.