Fast Curing Epoxy Systems via Brønsted Acid Salts
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Solution Overview
Problem
Existing epoxy resin systems cure too slowly or require high temperatures, which is a limitation for applications requiring quick surface hardening or low-temperature curing, such as corrosion protection in cold environments.
Innovation Solution
A composition comprising at least one epoxy resin, a cyclic amine of specific formula, and a salt of a Brönstedt acid with a pKa value less than or equal to 2, with a ratio of epoxy groups to amine groups optimized to enhance curing speed, allowing for rapid curing at temperatures well below room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional epoxy resin systems are used, then good chemical and solvent resistance is achieved, but curing speed is too slow or requires high temperatures
Solution Approach 1:
The patent changes the chemical parameters of the curing system by introducing a specific cyclic amine structure (with R1-R6 substituents) and optimizing the epoxy group to amine group ratio, enabling fast curing at low temperatures without compromising chemical resistance
Solution Approach 2:
The patent uses a specific cyclic amine compound as an intermediary curing agent that mediates between the epoxy resin and the curing process, enabling rapid reaction at low temperatures while maintaining the desired chemical and solvent resistance properties
2Speed
If catalysts are used to accelerate curing, then curing speed increases, but stability issues occur (e.g., imidazoline yellowing and instability with moist materials)
Solution Approach 1:
The patent employs a cyclic amine compound that acts as a temporary, stable curing agent during the reaction process, then becomes part of the stable crosslinked network, eliminating the need for persistent catalysts that cause yellowing or instability
Solution Approach 2:
The patent changes the chemical nature of the curing agent from conventional catalysts like imidazoline to a specific cyclic amine structure, which provides rapid curing without the stability problems of traditional catalysts
3Ease of operation
If aminoethylpiperazine is used as hardener, then curing can proceed without catalyst, but curing speed remains too slow for many applications
Solution Approach 1:
The patent modifies the molecular structure of the cyclic amine hardener by introducing specific substituents (R1-R6) and optimizing the epoxy group to amine group ratio, dramatically increasing curing speed while maintaining catalyst-free operation
Solution Approach 2:
The patent uses a cyclic amine compound with optimized structure that provides more than sufficient reactivity to achieve fast curing without catalyst, exceeding the minimum requirements for catalyst-free curing
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 achieves significantly faster curing compared to prior formulations, enabling quicker surface hardening and improved productivity, especially in cold conditions, without the stability issues associated with previous catalysts like imidazoline.
Implementation Method 1
Catalysts can be used to accelerate the curing of epoxy-amine coating systems
Implementation Method 2
a salt of a Brönstedt acid with a pKa value less than or equal to 2
Data Source
AI summary
The present invention relates to a composition comprising a) at least one epoxy resin, b) at least one cyclic amine of formula (I) in which - R1 to R4 represents H or an organic residue, - with the proviso that at least one of the residues R1, R2, R3 and R4 is H, and - X = -(Y1)m-(A1)n-(Y2)o-(A2)p-(Y3)q-(A3)r-(Y4)s- (II) wherein independently of each other - m, n, o, p, q, r and s = 0 or 1, - A1, A2, A3 = alkylene or alkenylene residue and - Y1, Y2, Y3, Y4 = NR5, PR5, O or S, wherein R5 independently of each other = organic residue, - wherein two organic residues are selected from R1 to R5 and any alkylene and/or alkenylene residues A1, A2, A3 can also form one or more further rings, - provided that at least one of the existing residues is selected from R1 to R5 and possiblyc) at least one of the alkylene and/or alkenylene residues A1, A2, A3 present is substituted with at least one group -NHR6 or -NH2, wherein R6 = organic residue, and c) at least one salt of a strong Brønsted acid with a counterion selected from metal ions, metal-containing ions, phosphonium ions and unsubstituted ammonium ions, wherein the ratio of the epoxy groups of the epoxy resin to the sum of all NH groups of all amines is 0.5 : 1 to 1.5 : 1. Processes for their preparation and their use.