Thiol Coating Latent Catalyst Cyclodextrin Pot-Life
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Solution Overview
Problem
Two-component coating compositions based on thiol-functional compounds and polyisocyanate cross-linking agents face challenges in achieving a balance between adequate pot-life and fast drying times at moderate temperatures, while maintaining good technological properties such as hardness and optical appearance.
Innovation Solution
The use of a latent catalyst compound comprising cyclodextrin and a catalyst, which forms a host-guest complex with the catalyst, allowing for extended pot-life and rapid curing in thiol/polyisocyanate systems, enabling coatings with improved processing time and drying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If catalysts are used to reduce drying time, then drying time is reduced, but pot life is reduced
Solution Approach 1:
Cyclodextrin acts as a mediator that forms an inclusion complex with the catalyst, temporarily deactivating it during storage and application. The catalyst is released from the cyclodextrin complex under application conditions (temperature, humidity, or UV irradiation), enabling rapid curing without compromising pot life. This intermediary mechanism resolves the contradiction between maintaining long pot life and achieving fast drying times.
Solution Approach 2:
The catalyst activity is controlled by changing physical parameters such as temperature, humidity, or UV exposure. At storage conditions, the catalyst remains deactivated in the cyclodextrin complex. Upon application, changes in temperature, humidity, or UV irradiation trigger catalyst release and activation, enabling rapid crosslinking. This parameter-based control allows independent optimization of pot life and drying time.
2Duration of action of moving object
If photolatent catalysts are used to extend pot life, then pot life is extended, but additional UV lamp equipment and sensitizers are required
Solution Approach 1:
The invention extracts and eliminates the need for UV lamp equipment and sensitizer additives by using cyclodextrin-based latent catalysts that can be activated by simpler means such as temperature, humidity, or direct UV exposure without requiring specialized curing equipment. This takes out the complex equipment requirement while maintaining the benefit of extended pot life.
Solution Approach 2:
The cyclodextrin complex serves as a simple, inexpensive, and self-contained latent catalyst system that does not require additional expensive equipment or sensitizer chemicals. The system is self-sufficient and can be activated by common environmental conditions, eliminating the need for complex UV curing equipment.
3Device complexity
If moisture-activated latent catalysts are used, then equipment complexity is reduced, but curing depends on environmental humidity
Solution Approach 1:
The catalyst activation mechanism is made dynamic and adjustable through multiple activation pathways (temperature, humidity, UV irradiation). This allows the curing process to be adapted to different environmental conditions and application requirements, providing versatility in controlling the curing process while maintaining equipment simplicity.
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
This approach results in coating compositions with a pot-life of 60 minutes to 20 hours and drying times of 5-30 minutes at 40-80°C, while maintaining excellent hardness, chemical resistance, and optical appearance.
Implementation Method 1
a catalyst compound, said catalyst compound comprising at least one catalyst for the curing reaction between the thiol groups of component A and the at least one free isocyanate group of component B, and at least one cyclodextrin
Implementation Method 2
at least one catalyst for the curing reaction between the thiol groups of component A and the at least one free isocyanate group of component B
Data Source
AI summary
The invention relates to a coating composition comprising:A) at least one thiol-functional compound having at least one thiol group,B) at least one polyisocyanate cross-linking agent with at least one free isocyanate group andC) at least one catalyst compound, said catalyst compound comprising at least one catalyst for the curing reaction between the thiol groups of component A and the free isocyanate groups of component B, and at least one cyclodextrine.