Tin-Based Latent Catalysts for Polyurethane Production
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current catalysts for polyurethane production often catalyze unintended side reactions, leading to poor mechanical properties and toxicity issues, particularly with mercury compounds being prohibited in certain industries.
Innovation Solution
The use of tetravalent mononuclear and polynuclear tin compounds with specific ligands, such as those bonded via oxygen or sulfur atoms and containing nitrogen, as latent catalysts to selectively catalyze polyisocyanate polyaddition reactions, avoiding toxicity and improving mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If customary catalysts (mercury compounds, lead compounds) are used to catalyze polyurethane reactions, then reaction speed is improved, but toxicity and harmful effects increase
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst system by replacing toxic mercury and lead compounds with tin compounds containing specific ligands (aminoalcohols, amino acids, or their derivatives). This parameter change maintains catalytic activity while eliminating toxicity, as the tin-based catalysts with organic ligands are non-toxic compared to conventional heavy metal catalysts.
Solution Approach 2:
The patent employs readily available tin compounds as catalysts that can be easily disposed of or degraded, replacing expensive and environmentally persistent toxic catalysts. The tin compounds with organic ligands are less costly, more environmentally friendly, and can be removed more easily from the final polyurethane product.
2Productivity
If catalysts are used to accelerate polyurethane reaction, then productivity is improved, but side reactions occur leading to poor mechanical properties
Solution Approach 1:
The patent applies local quality by designing catalysts with specific molecular structures (tin compounds with particular aminoalcohol or amino acid ligands) that create localized catalytic sites selective for the desired polyaddition reaction. This specificity ensures that only the main reaction is catalyzed while side reactions are suppressed, improving both productivity and product quality.
Solution Approach 2:
The organic ligands (aminoalcohols, amino acids) act as intermediaries between the tin catalyst and the reactants. These ligands modulate the catalytic activity and selectivity, allowing the catalyst to accelerate the main reaction while preventing unwanted side reactions through steric and electronic effects of the ligand molecules.
3Loss of time
If latent catalysts are used to achieve long pot lives and fast demoulding, then processing time is improved, but reaction control becomes more difficult
Solution Approach 1:
The patent employs dynamic catalyst activation where the tin compounds with organic ligands remain dormant at lower temperatures but become actively catalytic at elevated temperatures. This dynamic behavior allows long pot lives at storage temperatures while enabling fast reaction initiation and demoulding when heat is applied, maintaining ease of operation through thermal control.
Solution Approach 2:
The patent utilizes temperature parameter changes to activate the latent catalyst. By controlling the temperature threshold, the reaction can be delayed during storage and then rapidly initiated during processing. The tin compound catalyst system responds predictably to temperature changes, making reaction control straightforward despite the latent nature of the catalyst.
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
These tin-based catalysts provide polyisocyanate polyaddition products with enhanced mechanical properties and delayed reaction initiation, followed by accelerated curing, while being free from toxic heavy metals like mercury and lead, and exhibit reduced fogging behavior.
Implementation Method 1
the reaction between the hydroxyl component and the NCO component has to be catalysed
Implementation Method 2
These catalysts are idle until the reaction mixture reaches a certain temperature. Above this temperature they are then active, preferably instantaneously active.
Implementation Method 3
becoming instantaneously active at a certain temperature (usually around 70° C.) only after slow heating of the mixture, usually by reason of the exothermic nature of the uncatalysed conversion of NCO groups with OH groups
Data Source
AI summary
The present invention relates to new catalysts and production thereof as well as the preferred use thereof in the production of polyisocyanate polyaddition products. The described catalysts are tetravalent tin compounds with at least one ligand bonded via at least one oxygen atom or sulfur atom and containing at least one nitrogen atom.