Epoxy Systems Using Triethylaminetetraamine and Tin Catalysts
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Solution Overview
Problem
Current epoxy resin systems for composite materials in the automotive industry face challenges with long cycle times and low glass transition temperatures, particularly due to the reclassification of diethylenetriamine (DETA) and the limitations of alternative fast-curing formulations, which hinder their widespread adoption in high-volume production.
Innovation Solution
A curable resin system comprising a liquid epoxy resin and a hardener component with 80-99.99% polyethylene tetraamine and 0.01-3.0% dimethyltin dineodecanoate, optionally including 1,4-diazabicyclo[2.2.2]octane, to achieve rapid curing and high glass transition temperatures without using toxic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If diethylenetriamine (DETA) is used as a fast curing amine, then rapid curing and short demold times are achieved, but the formulation is reclassified as Toxic plus (T+) and cannot be used in automotive industry
Solution Approach 1:
The patent changes the chemical composition parameters by replacing DETA with polyethylene tetraamine (PET) and adjusting the catalyst system to tin-based compounds. This parameter change maintains the fast curing characteristics while eliminating the toxicity issue, as PET is not reclassified as toxic and the tin catalyst provides controlled curing kinetics.
Solution Approach 2:
The patent employs a tin catalyst system that provides rapid initial curing action (short-living effect) followed by controlled post-curing. The catalyst enables fast reaction during mold filling but the system is designed to complete curing within acceptable time frames, effectively using the catalyst's rapid action only when needed for productivity.
2Object-affected harmful factors
If alternative fast curing formulations replace DETA, then toxicity is reduced, but glass transition temperature drops below 130°C causing deformation during painting and coating processes
Solution Approach 1:
The patent changes the amine structure from linear (PET) to cycloaliphatic or aromatic structures, which fundamentally alters the polymer chain flexibility and intermolecular spacing. This structural parameter change increases the glass transition temperature to 130-150°C or higher, providing thermal stability during painting and coating operations while maintaining non-toxicity.
Solution Approach 2:
The patent creates a composite hardener system combining multiple amine components (cycloaliphatic amines, aromatic amines, and potentially DABCO) in specific ratios. This composite approach leverages the high Tg characteristics of cycloaliphatic and aromatic amines while using smaller amounts to maintain curing speed, achieving both thermal stability and rapid curing.
3Temperature
If cycloaliphatic or aromatic amines are used to boost glass transition temperature, then thermal performance is improved, but curing reaction slows significantly and post-curing steps are required
Solution Approach 1:
The patent segments the curing process into two distinct stages: a rapid initial curing phase driven by the tin catalyst and primary amine reaction (achieving Tg in 5-15 minutes), followed by a controlled post-curing phase that completes the crosslink density. This segmentation allows fast production while achieving full thermal performance.
Solution Approach 2:
The patent creates a dynamic curing profile where the reaction rate is initially very high during mold filling (enabling fast production), then naturally slows as the system approaches gel point and completes curing. The tin catalyst system provides this dynamic behavior, delivering rapid initial cure followed by controlled final curing without requiring external intervention.
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
This system enables short demold times and high glass transition temperatures, reducing cycle times and improving production efficiency while avoiding the use of toxic substances, thus addressing the limitations of existing formulations.
Implementation Method 1
a hardener component comprising a tin catalyst and 80 to 99.99 wt % of a polyethylene tetraamine mixture
Data Source
AI summary
The invention relates to curable epoxy resin systems comprising polyethylene tetraamine and a tin catalyst as hardening agents, and optionally comprising 1,4-diaza[2.2.2]bicyclo octane. The invention also relates to articles made therefrom, including composites such as carbon fiber reinforced composites. The curable epoxy resins have rapid demold times and/or high glass temperature.