Tin-Free Silane Crosslinking Catalyst for Polyurethane Coatings
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Solution Overview
Problem
Existing coating systems, particularly two-component polyurethane-based paints, rely on toxic tin compounds and aminosilanes for rapid curing, which are not compatible with all substrates and require specific temperature conditions, limiting their versatility and safety.
Innovation Solution
Development of an aminosilane-free composition comprising adducts of isocyanatosilanes with hydroxy-functional compounds and a tin-free catalyst, allowing for curing over a wide temperature range (0°C to 170°C) and compatibility with two-component polyurethane systems without using toxic tin or aminosilanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tin compounds and aminosilanes are used as catalysts, then crosslinking speed is improved, but toxicity increases and compatibility with substrates is reduced
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by replacing toxic tin compounds and aminosilanes with organometallic catalysts containing aluminum, boron, or zinc. This substitution maintains the catalytic function for crosslinking while eliminating the toxicological problems associated with conventional catalysts, thus resolving the contradiction between productivity and harmful factors.
Solution Approach 2:
The patent employs organometallic catalysts that are effective at very low concentrations (0.01-5 wt%) and can be easily removed or degraded after curing. These catalysts fulfill their function rapidly during the crosslinking process without leaving persistent toxic residues, addressing both the speed requirement and the toxicity concern.
2Productivity
If aminosilane-containing coating agents are used, then crosslinking speed is improved, but compatibility with 2K polyurethane systems is reduced
Solution Approach 1:
The patent extracts the problematic aminosilane component from the coating system while retaining the desired rapid crosslinking capability. By removing aminosilanes and using alternative organometallic catalysts with isocyanatosilane crosslinkers, the system achieves fast curing without the incompatibility issues that arise when aminosilanes react with polyisocyanates in 2K systems.
3Productivity
If methanol-releasing components are used to ensure crosslinking speed, then productivity is improved, but toxicological safety is reduced
Solution Approach 1:
The patent converts the potential harm of using aggressive crosslinking agents into a benefit by selecting isocyanatosilane crosslinkers that release non-toxic byproducts (such as ammonia or water depending on the specific silane structure) rather than methanol. The organometallic catalysts enable these crosslinking reactions to proceed rapidly without requiring methanol-releasing components, thus maintaining productivity while eliminating the harmful emissions.
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 enables stable, rapid curing at various temperatures, reduces toxicity, and enhances mechanical and chemical resistance of coatings, while maintaining flexibility and compatibility with different substrates.
Implementation Method 1
a tin-free catalyst, in particular an organometallic catalyst, is used
Data Source
AI summary
The present invention relates to a composition comprising at least A) an adduct of isocyanatosilanes to hydroxy-functional compounds and B) a tin-free catalyst, as well as a coating agent comprising at least the composition, the use of the coating agent.