Epoxy Resin Curing Agent Composition for Low Viscosity and Water Resistance
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Solution Overview
Problem
Existing epoxy resin compositions using polyamine compounds as curing agents suffer from high viscosity and reduced water resistance due to amine blushing, leading to sticky surfaces and compromised coating performance.
Innovation Solution
A modified amino compound derived from a predetermined aliphatic diamine, such as bis(aminomethyl)cyclohexane, is synthesized through a reaction with an aldehyde compound followed by reduction, resulting in a low-viscosity epoxy resin curing agent that forms coatings with enhanced water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyamine compound such as bis(aminomethyl)cyclohexane is used as an epoxy resin curing agent, then the coating film exhibits excellent weather resistance and fast curing at room temperature, but amine blushing occurs on the surface making it sticky and reducing water resistance
Solution Approach 1:
The invention modifies the chemical structure of the polyamine compound by introducing specific cyclic groups and controlling the ratio of primary to secondary amino groups (where the ratio of primary amino groups is 0.05 to 2.0 mol/mol of secondary amino groups). This structural parameter change eliminates amine blushing while maintaining fast curing and weather resistance properties.
Solution Approach 2:
The curing agent combines multiple functional groups within a single molecular structure - cyclic groups for structural stability, primary amino groups for reactivity and crosslinking, and secondary amino groups for controlled curing rate. This composite molecular structure achieves both fast curing and excellent water resistance without amine blushing.
2Object-affected harmful factors
If modified products of polyamine are used as epoxy resin curing agents to improve water resistance, then water resistance is enhanced, but the viscosity becomes high
Solution Approach 1:
The invention carefully controls the molecular weight and structural complexity of the modified polyamine by limiting the types of cyclic groups introduced and controlling the amino group ratios. This parameter optimization maintains low viscosity for easy application while achieving excellent water resistance through the engineered molecular structure.
3Ease of operation
If non-reactive diluents are added to reduce viscosity of modified polyamine curing agents, then viscosity is reduced, but water resistance is compromised
Solution Approach 1:
Instead of using non-reactive diluents that temporarily reduce viscosity but compromise water resistance, the invention designs the curing agent molecule itself to have appropriate fluidity through controlled molecular structure. The molecule acts as its own vehicle, eliminating the need for sacrificial diluents that would harm water resistance.
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 compound achieves low viscosity and forms coatings with excellent water resistance, improving the durability and appearance of epoxy resin films without the need for non-reactive diluents.
Implementation Method 1
reacting a diamine represented by the following general formula (5) and an aldehyde compound represented by the following general formula (6) to obtain an imine
Implementation Method 2
the step of reducing the imine obtained in the step (1)
Data Source
AI summary
An amino compound represented by formula (1) and a method for producing the same, an epoxy resin curing agent containing the amino compound, an epoxy resin composition, and a cured product thereof: R1—NH—X—NH—R2 (1) wherein R1 and R2 are each independently a hydrogen atom or a monovalent group represented by formula (2), at least one of R1 and R2 is a monovalent group represented by formula (2), X is a divalent group represented by —CH2—A—CH2— (A is a cyclohexylene group), —(CH2)n—, —(CH2CH2NH)m—CH2CH2—, or a divalent group represented by formula (3) or (4), n is 2 to 6, and m is 1 or 2,wherein a dashed line indicates presence or absence of a π bond, R3 to R5 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