Crosslinkable Composition Using Latent Base Catalyst
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High solids content coating compositions face challenges in achieving a balance between rapid crosslinking and long pot life, particularly at low to moderate temperatures, due to the limitations of existing latent base catalyzed Michael addition reactions, which often result in short pot lives, inhibition issues, and yellowing under stoving conditions.
Innovation Solution
A latent base catalyst composition comprising a substituted carbonate salt that decomposes to release a strong base upon drying, allowing for extended pot life and fast curing, while maintaining compatibility with high solids content and avoiding yellowing, achieved through the use of a substituted carbonate salt catalyst that becomes active upon evaporation of carbon dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a strong base catalyst is used to accelerate crosslinking in high solids coatings, then the drying rate is improved, but the pot life becomes too short for practical application
Solution Approach 1:
The catalyst is blocked in advance by reacting it with a blocking agent (carboxylic acid or sulfonic acid) to form a stable complex that is inactive during storage and mixing. This preliminary blocking action allows the catalyst to be prepared and stored without causing premature crosslinking, extending the pot life. Upon application and heating, the blocking agent is eliminated and the catalyst becomes active to accelerate drying.
Solution Approach 2:
A blocking agent (carboxylic acid or sulfonic acid) is introduced as an intermediary substance that temporarily deactivates the strong base catalyst. This intermediary forms a stable complex with the catalyst during storage, preventing premature activation. When the coating is applied and heated, the blocking agent is eliminated, releasing the active catalyst to promote rapid crosslinking.
2Object-affected harmful factors
If the solids content is increased to reduce environmental burden, then the VOC emission is reduced, but the balance between pot life and drying rate becomes more difficult to achieve
Solution Approach 1:
The invention changes the parameters of the catalyst system by using a blocked catalyst that can be stored in an inactive state and then activated upon application. This parameter change allows high solids formulations to maintain both long pot life (due to blocked catalyst stability) and fast drying (when catalyst is activated by heating), resolving the adaptability issue without compromising VOC reduction.
3Duration of action of moving object
If existing latent base catalysts are used to extend pot life, then the working time is improved, but yellowing occurs under stoving conditions
Solution Approach 1:
The invention changes the chemical parameters of the catalyst system by using a blocked catalyst architecture where the strong base is complexed with a blocking agent. This parameter change allows the catalyst to remain stable during storage (extending pot life) and eliminates the yellowing issue under stoving conditions, as the blocked structure prevents the harmful side reactions that cause yellowing while still enabling effective catalysis when activated.
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 solution provides a crosslinkable composition with a long workable pot life and fast drying behavior, even at high solids content, without the issues of yellowing or inhibition, enabling effective application and curing of high solids coatings.
Implementation Method 1
A latent base catalyst composition comprising a substituted carbonate salt that decomposes to release a strong base upon drying
Implementation Method 2
becomes active upon evaporation of carbon dioxide
Data Source
AI summary
The present invention relates to a crosslinkable composition comprising reactive components A and B each comprising at least 2 reactive groups wherein the at least 2 reactive groups of component A are acidic protons (C-H) in activated methylene or methine groups and the at least 2 reactive groups of component B are activated unsaturated groups (C=C) to achieve crosslinking by Real Michael Addition (RMA) in the presence of base catalyst C wherein the component A is a malonate containing component and wherein the crosslinkable composition comprises in addition to the malonate component A, a second component A2 comprising reactive acidic protons having a higher acidity than component A and also is reactive towards component B.