Polyurea Coating Hardener for Fast Spray Curing and Durability
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Solution Overview
Problem
Existing polyurea coatings face challenges with amine hardeners that are either hazardous, expensive, or result in undesirable properties such as hydrophilicity, high viscosity, or poor temperature stability, making them unsuitable for high-quality coatings with rapid walkability and resistance to environmental conditions.
Innovation Solution
Using a hardener containing a dimer fatty acid-based amine with a molar ratio of 40/60 to 90/10 free and blocked amine groups, allowing for rapid curing and good processability in a two-component spray application, even under varying ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If aromatic amines like DETDA are used as hardeners, then the polyurea coating achieves high reactivity and fast curing, but the coating becomes hazardous to health and environment with poor labeling
Solution Approach 1:
The patent changes the chemical structure parameter of the amine hardener from aromatic (DETDA) to aliphatic dimer fatty acid-based amine. This structural parameter change maintains the necessary reactivity for polyurea formation while eliminating the toxic aromatic rings, thus resolving the contradiction between curing speed and toxicity.
Solution Approach 2:
The patent uses dimer fatty acid-based amines which are derived from renewable resources and are less hazardous, effectively replacing the harmful aromatic amines with a safer alternative that achieves the same functional goal without the harmful side effects.
2Speed
If aminobenzoates of poly(1,4-butanediol) are used as hardeners, then the polyurea coating achieves suitable reactivity, but the hardener becomes expensive and highly viscous requiring significant dilution with thinners
Solution Approach 1:
The patent changes the physical state parameter of the hardener from highly viscous or solid (aminobenzoates) to liquid form by using dimer fatty acid-based amines. This parameter change eliminates the need for dilution with VOC solvents while maintaining suitable reactivity, thus resolving the contradiction between reactivity and processing complexity.
3Ease of operation
If polyetheramines are used as hardeners, then the polyurea coating achieves good processability, but the cured coating becomes hydrophilic with reduced resistance
Solution Approach 1:
The patent changes the chemical composition parameter by replacing polyetheramine-based hardeners with dimer fatty acid-based amines. This parameter change eliminates the hydrophilic ether groups while maintaining the amine functionality needed for polyurea formation, thus resolving the contradiction between processability and resistance to moisture.
4Speed
If the amine hardener has very high reactivity, then rapid curing is achieved, but the coating hardens in the spray nozzle causing nozzle formation
Solution Approach 1:
The patent optimizes the reactivity parameter by using dimer fatty acid-based amines which provide moderate reactivity - fast enough to achieve rapid walkability after application but slow enough to prevent hardening in the spray nozzle. This parameter optimization resolves the contradiction between curing speed and spray application processability.
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 polyurea coatings exhibit excellent adhesion, mechanical properties, and resistance to high temperatures, UV radiation, moisture, and chemicals, enabling applications in demanding environments like roofs, food processing plants, and swimming pools.
Implementation Method 1
the hardener contains at least one dimer fatty acid-based amine A1 and, if necessary, at least one other amine A2 for the curing of at least one polyisocyanate
Implementation Method 2
Blocked amines do not react with isocyanates in the absence of moisture. Upon exposure to moisture, the reaction with isocyanates occurs, releasing the corresponding aldehyde or ketone.
Data Source
AI summary
The invention relates to the use of a hardener for curing at least one polyisocyanate, wherein the hardener comprises at least one dimer fatty acid-based amine A1 and optionally at least one further amine A2, and contains free amine groups and blocked amine groups in a molar ratio of 40/60 to 90/10. This enables the production of polyurea coatings that are readily processable by two-component spray application and cure very quickly. The resulting polyurea coatings possess excellent mechanical properties and very high stability against temperature, UV radiation, moisture, and chemicals. They are particularly suitable as protective coatings for objects subject to heavy wear, such as those in swimming pools.