Bismuth-Tin Catalyst Mixture for Stable Polyurethane Foam
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Solution Overview
Problem
Conventional polyurethane catalyst compositions face challenges in forming stable mixtures at ambient conditions, particularly in spray foam processes, and require higher catalyst content to achieve desirable foam properties, leading to increased costs and environmental concerns.
Innovation Solution
A storage-stable liquid catalyst composition combining liquid bismuth carboxylate salts and dialkyltin dicarboxylate complexes, which form homogeneous mixtures at ambient conditions, allowing for reduced catalyst usage while maintaining foam quality and cure rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organometallic catalyst compositions are used, then foam properties can be achieved, but the catalyst mixtures form precipitates at ambient conditions interfering with manufacturing processes
Solution Approach 1:
The patent introduces a specific solvent system (comprising esters of polybasic acids and polyhydric alcohols) as an intermediary medium that enables the formation of stable homogeneous catalyst mixtures. This solvent acts as a mediator between the incompatible organometallic catalysts, preventing precipitate formation while maintaining catalytic activity and foam quality.
Solution Approach 2:
The patent changes the physical and chemical parameters of the catalyst composition by selecting specific solvent types (esters with particular molecular weight ranges and hydroxyl content). By adjusting these parameters, the mixture remains homogeneous and stable at ambient conditions, eliminating precipitation issues while preserving foam properties.
2Reliability
If higher catalyst content is used to achieve desirable foam properties, then foam quality improves, but costs increase and environmental concerns worsen
Solution Approach 1:
The patent optimizes the concentration parameters of the catalyst components within specific ranges (0.01-10% by weight of each catalyst in the polyol). This parameter optimization achieves desirable foam properties while minimizing the total catalyst quantity required, thereby reducing costs and environmental impact.
Solution Approach 2:
The patent creates a composite catalyst system combining multiple organometallic catalysts (organotin, organobismuth, and/or organosilver compounds) in specific ratios. This composite approach enhances catalytic efficiency, allowing lower overall catalyst loading while maintaining or improving foam quality compared to single-catalyst systems.
3Stability of the object's composition
If catalysts are segregated in separate components, then chemical and physical stability is maintained, but process complexity increases and additional mixing equipment is required
Solution Approach 1:
The patent merges multiple catalyst components into a single homogeneous liquid composition that remains stable at ambient conditions. By combining the catalysts in a compatible solvent system, the need for separate storage and complex mixing equipment is eliminated, simplifying the manufacturing process while maintaining stability.
Solution Approach 2:
The patent changes the composition parameters to ensure complete miscibility of catalyst components at all relevant temperatures and concentrations. This parameter optimization allows the catalysts to be pre-mixed into a single stable composition without phase separation, eliminating the need for complex segregation and remixing procedures.
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 catalyst composition achieves balanced cure profiles and improved foam properties with significantly lower overall catalyst content, enabling stable foam production across various manufacturing processes, including spray foam, without the need for segregation of catalysts.
Implementation Method 1
Catalysts are compounds that help promote the reactions between an isocyanate and isocyanate-reactive compounds and the isocyanate polymerization reaction
Implementation Method 2
the blowing reaction (reaction of water with isocyanate to generate carbon dioxide)
Implementation Method 3
in those applications desiring the production of isocyanurate (trimer), if a catalyst does not generate enough heat (exothermic reaction) early on in the reaction
Data Source
AI summary
A composition and process to make polyurethane foam using a stable liquid catalyst composition comprising at least one liquid bismuth carboxylate catalyst and at least one liquid dialkyltin dicarboxylate complex are disclosed. The disclosed composition and process yield polyurethane foam having favorable properties, but requiring less metal. The polyurethane foams produced by this catalyst composition and method are useful for laminated boardstock, construction panels, appliance insulation, spray-applied insulation, seat cushions, and mattresses.