Epoxy Curing Agent Reduces Blushing and Improves Bond Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Epoxy resin-based coatings and adhesives often suffer from surface defects such as haze, spots, roughness, or blushing, particularly at high humidity and low temperatures, due to the reaction of amines with carbon dioxide, which affects their esthetic and functional properties.
Innovation Solution
A curing agent for epoxy resins is developed, comprising a specific combination of at least one alkylated amine A1 and at least one polyalkyleneamine or polyethyleneimine A2, which balances viscosity, curing rate, glass transition temperature, and brittleness, while minimizing blushing-related defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If alkylated amines are used as curing agents, then blushing is reduced and viscosity is lowered, but curing rate decreases and glass transition temperature decreases
Solution Approach 1:
The invention uses a composite curing agent system combining alkylated amine (Formula I) with polyalkyleneimine or polyethyleneimine (Formula II). This composite approach allows the alkylated amine to reduce blushing while the polyalkyleneimine maintains curing rate, achieving both benefits simultaneously through synergistic interaction between the two amine components.
Solution Approach 2:
The invention optimizes the molecular structure parameters of the alkylated amine (Formula I) by controlling the alkyl chain length (1-12 carbon atoms) and the aromatic/cycloaliphatic radical substitution patterns. These parameter adjustments reduce the amine's CO2 reactivity (reducing blushing) while maintaining sufficient reactivity for acceptable curing rates when combined with Formula II amines.
2Productivity
If polyalkyleneimines such as TETA, TEPA or N4 amine are used, then rapid curing is achieved, but blushing increases and brittleness increases
Solution Approach 1:
The invention combines polyalkyleneimine (Formula II) with alkylated amine (Formula I) in a composite curing system. The polyalkyleneimine provides rapid curing capability while the alkylated amine component suppresses blushing. This composite approach balances the opposing effects of the two amine types to achieve both fast curing and low blushing.
Solution Approach 2:
The invention introduces the alkylated amine (Formula I) as a localized component within the curing agent system to specifically address the blushing problem in regions where polyalkyleneimine causes excessive CO2 reaction. This local quality adjustment allows rapid curing to occur while blushing is suppressed at the surface.
3Productivity
If polyalkyleneimines such as TETA, TEPA or N4 amine are used, then rapid curing is achieved, but brittleness increases and bond strength decreases
Solution Approach 1:
The composite curing agent system combines polyalkyleneimine (Formula II) for rapid curing with alkylated amine (Formula I) that produces less brittle cured products. This combination maintains fast curing kinetics while reducing brittleness and improving bond strength through the complementary properties of the two amine components.
Solution Approach 2:
The invention adjusts the molecular structure parameters of the curing agent system by controlling the ratio and structure of Formula I and Formula II amines. This parameter optimization balances curing rate with mechanical properties, ensuring adequate bond strength and flexibility while maintaining rapid curing characteristics.
4Ease of operation
If conventional thinners such as benzyl alcohol are used, then viscosity is reduced and application is improved, but emissions increase
Solution Approach 1:
The invention changes the chemical composition parameters of the curing agent system by using alkylated amines with specific molecular structures (Formula I) that inherently reduce CO2 reactivity. This parameter change reduces blushing without requiring conventional volatile thinners, thus maintaining ease of application while minimizing emissions.
Solution Approach 2:
The invention replaces conventional volatile organic thinners with a chemically active curing agent system that provides both viscosity control and blushing suppression. The alkylated amine (Formula I) acts as a functional thinner that is incorporated into the polymer matrix, eliminating the need for separate volatile thinner components and reducing emissions.
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 curing agent achieves low viscosity and rapid curing with minimal blushing, resulting in high-strength, low-brittleness products with high bond strength and glass transition temperature, suitable for both coatings and adhesives, especially under cold and moist conditions.
Implementation Method 1
A curing agent for epoxy resins is developed, comprising a specific combination of at least one alkylated amine A1 and at least one polyalkyleneamine or polyethyleneimine A2
Implementation Method 2
Blushing is caused by the amines present in the curing agent component forming a salt with carbon dioxide (CO2) from the air
Data Source
AI summary
A curing agent for epoxy resins, including at least one amine A1 of the formula (I) and at least one amine A2 which is a polyalkyleneamine or polyethyleneimine, where the weight ratio between amine A1 and amine A2 is in the range from 20/1 to 1/2. The curing agent of the invention enables inexpensive and low-emission epoxy resin products having good processability, long pot life, surprisingly rapid curing, especially also under cold conditions, high strength, high bond strengths, high glass transition temperature and a low tendency to yellowing, with formation of surprisingly nice surfaces having barely any blushing-related defects even in the case of two-dimensional application and under moist and cold conditions. Such epoxy resin products are advantageously usable as coating, especially for floors, or as adhesive.