Aqueous Epoxy-Amine Coating With Aromatic Acid Low-Temp Curing
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Solution Overview
Problem
Existing aqueous epoxy-amine systems used in automotive refinishing suffer from reduced intercoat adhesion, blistering stability under humidity, and stone chipping resistance, especially when using catalysts like Ancamine K54 or salicylic acid, necessitating compositions that cure rapidly at low temperatures without compromising adhesion, blistering stability, and stone chipping resistance.
Innovation Solution
An aqueous coating composition comprising an epoxy resin dispersion, an amine-functional resin dispersion, and an aromatic carboxylic acid as a curing catalyst, with specific components selected to enhance curing speed and adhesion, including a polyfunctional organic amine and a resin component with a reactive polyoxyalkylene unit, achieving rapid curing at 80°C or lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional curing catalysts (Ancamine K54 or salicylic acid) are used in aqueous epoxy-amine systems, then curing speed is improved, but intercoat adhesion deteriorates
Solution Approach 1:
The patent changes the chemical parameter of the curing catalyst from traditional options (Ancamine K54 or salicylic acid) to a specific aromatic carboxylic acid with defined structural characteristics. This parameter change enables the system to achieve both rapid curing and maintained intercoat adhesion, resolving the contradiction between curing speed and adhesion strength.
2Productivity
If traditional curing catalysts (Ancamine K54 or salicylic acid) are used in aqueous epoxy-amine systems, then curing speed is improved, but blistering stability under humidity deteriorates
Solution Approach 1:
The patent modifies the chemical parameter of the curing catalyst to a specific aromatic carboxylic acid structure that maintains curing acceleration while improving resistance to humidity-induced blistering. This parameter change resolves the contradiction between fast curing and long-term reliability under humid conditions.
3Productivity
If traditional curing catalysts (Ancamine K54 or salicylic acid) are used in aqueous epoxy-amine systems, then curing speed is improved, but stone chipping resistance deteriorates
Solution Approach 1:
The patent changes the chemical parameter of the curing catalyst to a specific aromatic carboxylic acid that enables rapid curing while preserving the mechanical strength needed to resist stone chipping. This resolves the contradiction between curing speed and impact resistance.
4Use of energy by stationary object
If curing is performed at low temperatures (80°C or lower), then energy consumption is reduced, but curing speed deteriorates
Solution Approach 1:
The patent changes the chemical parameter of the curing catalyst to an aromatic carboxylic acid that maintains high catalytic activity at low temperatures (80°C or lower). This enables the system to achieve both low energy consumption and acceptable curing speed, resolving the contradiction between energy efficiency and productivity.
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 composition results in coatings with excellent adhesion to substrates, high intercoat adhesion, and blistering stability under humidity, while maintaining good sandability and stone chipping resistance, suitable for automotive refinishing.
Implementation Method 1
an aromatic carboxylic acid (C) as curing catalyst
Data Source
AI summary
Disclosed herein is an aqueous coating composition containing an aqueous epoxy resin dispersion, an aqueous amine-functional resin dispersion and an aromatic carboxylic acid. The aqueous dispersion contains at least one specific di- and/or polyfunctional monomeric amine and at least one resin component including at least one specific polyfunctional organic amine. Further disclosed herein is a kit-of-parts including a base varnish containing the aqueous epoxy resin dispersion and a curing component containing the aqueous amine-functional resin dispersion as well as the aromatic carboxylic acid. Additionally disclosed herein is a process for producing a coating on the substrate as well as coated substrates resulting from said process. Cured coating layers formed from said compositions exhibit a good adhesion to the substrate as well as a high intercoat adhesion and blistering stability under humidity conditions without negatively influencing the excellent sandability and the good stone chipping properties.