Low-emission epoxy hardener with reduced viscosity and blushing
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Solution Overview
Problem
Epoxy resin compositions face challenges in achieving low viscosity, quick hardening, and avoiding blushing effects, especially in cold and humid conditions, while also requiring low-emission systems that do not use non-incorporatable thinners, which are often high in odor and irritating.
Innovation Solution
A hardener comprising an amine of specific formula (I), derived from reductive alkylation of 1,3-bis-(aminomethyl)benzene with benzaldehyde, combined with a polyamine having reactive amine hydrogens, which reduces viscosity and prevents blushing, allowing for rapid curing and high hardness without the need for non-incorporatable thinners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-incorporatable thinners (benzyl alcohol, phenols) are used to reduce viscosity and brittleness, then processability and film flexibility improve, but emission levels increase and eco-label compliance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by using a specific amine ratio (0.05-5 weight ratio of amine with primary amino groups to polyamine) to achieve the desired balance between processability and low emissions without non-incorporatable thinners
Solution Approach 2:
The patent creates a composite hardening system combining two types of amines (primary amino group-containing amine and polyamine) to achieve properties that neither component alone could provide, eliminating the need for harmful thinners
2Ease of operation
If low molecular weight amines (isophoronediamine, xylylenediamine, dimethylaminopropylamine) are used to dilute epoxy resin compositions, then viscosity decreases and processability improves, but odor intensity increases and skin irritation worsens
Solution Approach 1:
The patent changes the molecular structure parameters by selecting amines with specific molecular weights and functional group compositions that provide adequate dilution effect while minimizing odor and irritation, departing from conventional low molecular weight amines
3Productivity
If amines with primary amino groups are used as hardeners, then reactivity with epoxy resins improves, but blushing effects increase in cold and humid conditions
Solution Approach 1:
The patent optimizes the amine composition parameters by controlling the ratio of primary amino group-containing amine to polyamine (0.05-5 weight ratio) to balance curing reactivity with resistance to blushing effects
Solution Approach 2:
The patent develops a composite amine system where the combination of primary amino group-containing amine and polyamine creates synergistic effects that reduce CO2 reaction products and blushing while maintaining curing speed
4Strength
If hardeners with high NH equivalent weight are used, then film hardness improves, but curing speed decreases
Solution Approach 1:
The patent optimizes the NH equivalent weight parameter by selecting specific amine combinations that achieve high film hardness without excessive molecular weight, balancing curing speed and final film properties
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 solution results in low-odor, low-viscosity epoxy resin systems that harden quickly and form high-gloss, defect-free films with low brittleness, meeting eco-label standards and improving processing and usage properties.
Implementation Method 1
the amine of formula (I) and also at least one polyamine A, which has at least three amine hydrogens that are reactive towards epoxide groups
Implementation Method 2
The hardener has a low odor, low viscosity and works excellently with epoxy resins
Data Source
AI summary
The invention relates to low-odor, low-viscosity hardeners for epoxy resins, comprising the amine of formula (I), and to a method for thinning hardeners for epoxy resins by adding the amine of formula (I). Said hardeners harden with epoxy resins quickly and without blushing to form films of high hardness and low brittleness, even without thinners that cannot be incorporated, such as benzyl alcohol. Said hardeners are suitable in particular for low-emission coatings.