Microencapsulated Polyaddition Catalyst for Extended Pot Life
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Solution Overview
Problem
Conventional resin systems with polyaddition catalysts have a short pot life and long cure time, making them unsuitable for efficient processing and rapid curing in applications like floor coatings and sealing membranes, as they often cure prematurely due to thermal stimuli rather than chemical triggers.
Innovation Solution
Microencapsulated polyaddition catalysts with a capsule core containing a polyaddition catalyst and an acrylic copolymer shell, where the copolymerized intermolecular anhydride units act as temporary crosslinkers, destabilizing the shell upon solvolysis to release the catalyst upon contact with isocyanate-curing substances like polyols or water, optimizing the release timing for extended pot life and rapid curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional polyaddition catalysts are used, then rapid curing is achieved, but the pot life becomes too short for practical processing
Solution Approach 1:
The catalyst is pre-encapsulated in microcapsules with a shell containing anhydride groups that are stable during storage and mixing. The encapsulation prepares the catalyst for controlled release only when the anhydride bonds are cleaved by water or polyols during the curing process, preventing premature catalysis and extending pot life while ensuring rapid curing when needed
2Loss of time
If the catalyst is released immediately, then curing starts right away, but the processing time becomes insufficient for proper application
Solution Approach 1:
The microcapsule shell acts as an intermediary barrier between the catalyst core and the resin mixture. The anhydride-containing shell material mediates the release process by being cleaved by water or polyols to trigger catalyst release, thereby controlling the timing of catalysis to occur only after proper mixing and application, ensuring both sufficient processing time and efficient curing
3Temperature
If thermal stimuli trigger catalyst release, then curing can be controlled, but use at ambient temperature is prevented
Solution Approach 1:
The patent changes the activation mechanism from thermal to chemical by incorporating anhydride groups in the capsule shell that undergo solvolysis with water or polyols at ambient temperatures. This parameter change in the triggering mechanism allows the catalyst to be released at room temperature, expanding the application temperature range while maintaining controlled release
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 microencapsulated catalysts provide a controlled release mechanism, allowing for a longer pot life and rapid curing, preventing premature hardening while ensuring sufficient catalyst is introduced for complete curing, thus enhancing the processing window and final product performance.
Implementation Method 1
the copolymerized units of the intermolecular anhydride of an ethylenically unsaturated carboxylic acid act as temporary crosslinkers, whose crosslinking action is halted by solvolysis of the anhydride bond in the application environment, thereby destabilizing the capsule shell and releasing the capsule contents including the polyaddition catalyst
Implementation Method 2
Microencapsulated polyaddition catalysts with a capsule core containing a polyaddition catalyst and an acrylic copolymer shell, where the copolymerized intermolecular anhydride units act as temporary crosslinkers, whose crosslinking action is halted by solvolysis of the anhydride bond in the application environment, thereby destabilizing the capsule shell and releasing the capsule contents including the polyaddition catalyst
Data Source
AI summary
A microencapsulated polyaddition catalyst comprises a capsule core, containing polyaddition catalyst, and an acrylic copolymer capsule shell, the acrylic copolymer comprising copolymerized units of an intermolecular anhydride of an ethylenically unsaturated C3-C12 carboxylic acid. The polyaddition catalyst is selected from acyclic tertiary amines, alicyclic tertiary amines, N-alkylimidazoles, phosphines and organic metal salts. It is suitable for catalysing the reaction of a polyol compound with a polyisocyanate compound. The polyaddition catalyst is released by a chemical stimulus, such as on contact with polyols or water, for example.