Delayed-Action Trimerization Catalyst for Polyisocyanate Potlife
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Solution Overview
Problem
Existing polyisocyanate trimerization reactions are too rapid and exothermic, making it difficult to handle polyisocyanate compositions in processes requiring extended processing times, such as resin transfer moulding, pultrusion, and prepreg composite applications, where a longer potlife is necessary.
Innovation Solution
A composition comprising a trimerization catalyst, selected from alkali metal carboxylates and quaternary ammonium carboxylates, obtained by reacting phthalic anhydride or trimellitic anhydride with a polyol, which delays the trimerization reaction, allowing for a stable one-component composition that remains non-reactive at ambient conditions for an extended period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polyisocyanate compositions are used, then the trimerization reaction proceeds rapidly, but the potlife is too short for extended processing times
Solution Approach 1:
The patent applies preliminary action by incorporating a delayed-action catalyst system into the polyisocyanate composition before use. The catalyst precursor (metal salt of carboxylic acid with 2-20 carbons) remains dormant during storage and handling, then activates under processing conditions (heat, moisture, or pH change) to initiate trimerization at the desired time, thus extending potlife while ensuring rapid curing when needed
Solution Approach 2:
The patent utilizes parameter changes by controlling the activation of the catalyst system through external stimuli. The catalyst precursor transforms from an inactive state to an active state through changes in temperature, moisture content, or pH during the processing cycle. This allows the same composition to exhibit different reactivity profiles at different stages: stable during handling (low reactivity) and rapidly curing during processing (high reactivity)
2Stability of the object's composition
If the trimerization reaction is delayed for extended processing, then the composition remains stable during handling, but the curing process must be initiated rapidly when processing begins
Solution Approach 1:
The patent prepares the composition in advance with a dormant catalyst precursor that maintains composition stability during storage and handling. The actual catalytic action is postponed until processing begins, when activation conditions are met. This preliminary preparation ensures the composition remains stable and handleable while being ready for rapid curing when triggered
Solution Approach 2:
The patent implements periodic action through the staged activation of the catalyst system. The composition transitions from a stable, low-reactivity state during handling to a high-reactivity curing state when activated by processing conditions. This periodic transition between dormant and active states allows the material to satisfy both stability requirements during handling and productivity requirements during curing
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 delayed trimerization reaction enables handling of polyisocyanate compositions with a longer potlife, followed by a fast and exothermic curing process, suitable for various industrial applications like resin transfer moulding and pultrusion, ensuring stability during processing and efficient curing.
Implementation Method 1
A composition comprising a trimerization catalyst, selected from alkali metal carboxylates and quaternary ammonium carboxylates
Implementation Method 2
obtained by reacting phthalic anhydride or trimellitic anhydride with a polyol
Implementation Method 3
followed by a fast and exothermic curing process
Data Source
AI summary
Isocyanurate-reactive mixture obtained by reacting an anhydride and a polyol; process for making it; polyisocyanate composition comprising this mixture; binder composition comprising such a polyisocyanate composition; the use of such a polyisocyanate composition and/or binder composition for making a polyisocyanurate and such polyisocyanurates.