Nitrogen Heterocyclic Epoxy Curing Agents for Low-Temperature Performance
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Solution Overview
Problem
Epoxy coatings suffer from slow cure at low temperatures, leading to surface defects and poor performance due to slow amine-epoxy reaction rates and incompatibility between amine curing agents and epoxy resins, while current high-reactivity curing agents pose health and safety concerns and regulatory issues.
Innovation Solution
Development of an amine-epoxy curing agent comprising saturated heterocyclic compounds with two nitrogen heteroatoms, which enhances compatibility with epoxy resins, accelerates curing, and reduces yellowing, using a reaction product of polyethylene polyamines and aldehydes, such as formaldehyde, to create a fast-curing, yellowing-resistant composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional amine curing agents are used, then epoxy resins can be cured, but the curing process is slow at low temperatures leading to poor surface defects and greasy surface appearance
Solution Approach 1:
The patent modifies the chemical structure of amine curing agents by introducing saturated heterocyclic compounds with specific nitrogen heteroatoms and controlled alkyl/aryl substitutions. This structural parameter change enables the curing agent to maintain high reactivity at low temperatures while preventing the slow cure issues and surface defects associated with traditional amines
Solution Approach 2:
The invention creates a composite curing agent system combining saturated heterocyclic compounds with polyethylene polyamine backbones. This composite structure integrates the low-temperature reactivity of heterocyclic rings with the crosslinking efficiency of polyamine chains, achieving both fast cure and complete reaction
2Reliability
If amine curing agents are used, then epoxy resins can be cured, but incompatibility causes phase separation and amine migration to the coating surface resulting in poor physical properties
Solution Approach 1:
The patent alters the hydrophobicity and molecular structure parameters of the curing agent by incorporating saturated heterocyclic rings with controlled alkyl and aryl groups. This parameter modification improves compatibility with epoxy resin, preventing phase separation and amine migration while ensuring complete curing
Solution Approach 2:
The saturated heterocyclic compound acts as a structural intermediary between the polyamine backbone and the epoxy resin. Its specific ring structure and substitution patterns mediate the interaction, improving compatibility and preventing the phase separation that occurs with traditional amine curing agents
3Loss of time
If free amine is present on the surface for too long a period, then the amine will react with water and carbon dioxide in the atmosphere, but this develops a white film on the surface which can lead to poor coating performance
Solution Approach 1:
The patent modifies the reactivity parameters of the amine curing agent through heterocyclic ring incorporation, enabling complete curing to occur within a shorter time frame. This parameter change ensures that free amine is consumed before it can react with atmospheric moisture and CO2 to form surface films
Solution Approach 2:
The improved curing agent performs the curing action more rapidly and completely, finishing the chemical reaction before the harmful secondary reaction with atmospheric components can occur. This preliminary completion of the primary curing function prevents the formation of white surface films
4Productivity
If traditional curing agents are used to speed up amine-epoxy reaction at low temperature, then cure time is reduced, but they can cause the epoxy resin to homopolymerize and the resultant system to become brittle
Solution Approach 1:
The patent changes the chemical reactivity parameters of the curing agent by incorporating saturated heterocyclic compounds with controlled nitrogen heteroatoms. This parameter change provides accelerated cure at low temperatures while maintaining appropriate crosslink density and flexibility, preventing the brittleness caused by traditional accelerators
Solution Approach 2:
The invention introduces specific functional groups (saturated heterocyclic rings with nitrogen heteroatoms) at specific locations in the curing agent molecule. This local structural quality enables enhanced reactivity where needed while maintaining overall molecular flexibility and preventing homopolymerization that leads to brittleness
5Reliability
If traditional curing agents are used, then amine-epoxy reaction can proceed, but yellowing occurs due to incomplete reaction and atmospheric exposure
Solution Approach 1:
The patent modifies the chemical stability parameters of the curing agent through the use of saturated heterocyclic compounds. This parameter change ensures complete and stable curing that prevents the formation of yellowing compounds, while the saturated ring structure itself is more resistant to oxidation and discoloration than traditional amine structures
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 amine-epoxy curing agent achieves faster curing at various temperatures, improves surface finish, and reduces health and safety hazards, providing a more efficient and safer alternative for industrial applications.
Implementation Method 1
The curing process is the chemical reaction of the epoxide groups in the epoxy resins and the reactive groups in the curing agents
Implementation Method 2
The epoxy resins can be crosslinked or cured by curing agents. The curing converts the epoxy resins, which have a relatively low molecular weight, into relatively high molecular weight materials by chemical addition of the curing agents to the epoxy resins
Data Source
AI summary
Amine-epoxy curing agents are disclosed including at least one saturated heterocyclic compound having two nitrogen heteroatoms according to formula (I) and at least one saturated fused bicyclic heterocyclic compound having three nitrogen heteroatoms according to formula (II):wherein X is independently selected from a hydrogen atom, a linear or branched C1 to C4 alkyl group and a substituted or un-substituted phenyl group, Y1 is a direct bond or a divalent polyethylene polyamine group having 1 to 8 nitrogen atoms or a divalent polyethylene polyamine derivative having 1 to 8 nitrogen atoms, Y2 is a direct bond or a divalent polyethylene polyamine group having 1 to 7 nitrogen atoms and R is independently a hydrogen atom or a group selected from C1-C8 linear, cyclic, and branched alkyl, alkenyl, and alkaryl groups.