Epoxy Resin Curing Agent Composition for Low-Blushing Coatings
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Solution Overview
Problem
Existing epoxy resin compositions using xylylenediamine as a curing agent face issues with blushing due to carbon dioxide and water vapor absorption, leading to reduced water resistance and chemical resistance, and high viscosity, which is exacerbated by the use of non-reactive diluents.
Innovation Solution
Amino compositions containing specific modified products of xylylenediamine, produced by reacting diamines with aldehydes and subsequent reduction, are used to form an epoxy resin curing agent with improved hydrophobicity and low viscosity, enhancing resistance to water-containing methanol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If xylylenediamine is used as an epoxy resin curing agent, then low-temperature curability and chemical resistance are improved, but blushing occurs due to carbon dioxide and water vapor absorption, deteriorating appearance
Solution Approach 1:
The harmful amino groups that absorb carbon dioxide and water vapor are removed from the curing agent structure. The patent uses a polyamine compound with reduced amino group content or replaced with less reactive groups, thereby extracting the problematic functionality while retaining the desired chemical resistance and low-temperature curability.
Solution Approach 2:
The chemical structure parameters of the curing agent are modified by selecting polyamine compounds with different molecular weights, amino group densities, or structural configurations. This changes the reactivity and absorption characteristics to prevent blushing while maintaining performance.
2Reliability
If modified products of xylylenediamine are used to reduce blushing, then water resistance is improved, but viscosity increases, requiring dilution with non-reactive diluents
Solution Approach 1:
The patent modifies the molecular weight and structural parameters of the polyamine compound to achieve low viscosity without requiring dilution. By selecting appropriate molecular weight ranges and structural configurations, the curing agent maintains low viscosity while preserving water resistance and other performance characteristics.
3Ease of operation
If non-reactive diluents are added to reduce viscosity, then ease of operation is improved, but chemical resistance of the coating film is reduced
Solution Approach 1:
The non-reactive diluent component is completely removed from the system. Instead of adding diluents to reduce viscosity, the patent selects polyamine compounds with inherently low viscosity, thereby extracting the need for harmful diluents while maintaining chemical resistance.
4Productivity
If polyamine compounds with high amino group content are used, then curing speed is improved, but absorption of carbon dioxide and water vapor increases, causing blushing
Solution Approach 1:
The patent optimizes the amino group content parameter within a specific range that balances curing speed and blushing resistance. By controlling the number and reactivity of amino groups, the curing agent achieves fast curing without excessive absorption of carbon dioxide and water vapor.
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 amino compositions provide low viscosity and excellent resistance to water-containing methanol, resulting in improved coating films with enhanced hardness, appearance, and water resistance.
Implementation Method 1
reacting a diamine represented by general formula (4) and an aldehyde compound represented by general formula (5) to obtain an imine
Implementation Method 2
the step of reducing the imine obtained in the step (1)
Data Source
AI summary
An amino composition containing an amino compound (A) represented by the following general formula (1) and an amino compound (B) represented by the following general formula (3), wherein a molar ratio between the amino compound (A) and the amino compound (B) [(A)/(B)] is 10/90 to 99/1 and a method for producing the same, an epoxy resin curing agent containing the composition, an epoxy resin composition, and a cured product thereof,wherein R1 is a monovalent group represented by the following general formula (2) and X is a phenylene group,wherein a dashed line indicates presence or absence of a π bond, R2 to R4 are each independently a hydrogen atom or an alkyl group that has 1 to 4 carbon atoms and optionally has a hydroxy group, and * represents a bonding position,wherein R1 and X are the same as above.