Low-Temperature Curable Compositions for Coatings
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Solution Overview
Problem
There is a need for an isocyanate-free crosslinking system that is curable at low temperatures, generates no volatile organic compounds (VOCs), and is suitable for coating and adhesive applications, as isocyanate-based systems pose health concerns and require heat for reaction, which is challenging to overcome at ambient temperatures.
Innovation Solution
A curable composition comprising a first component with β-ketoester or malonate functional groups and a second component with aldehyde functional groups, along with a basic catalyst, which allows for low-temperature curing without the use of isocyanates, VOCs, or heat, suitable for coatings and adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If isocyanate crosslinkers are used for low-temperature curing, then the system can cure at ambient temperatures, but the system generates VOCs and poses health concerns
Solution Approach 1:
The patent removes isocyanate crosslinkers from the coating system entirely, extracting the harmful component while maintaining the crosslinking function through an alternative chemistry (carboxyl group condensation reactions). This eliminates VOC generation and health concerns while preserving low-temperature curing capability.
Solution Approach 2:
The invention changes the chemical reaction parameters by using carboxyl group condensation instead of isocyanate addition reactions. This parameter change allows the system to cure at ambient temperatures without generating harmful VOCs, as the condensation reaction proceeds through a different mechanism that does not require isocyanates.
2Use of energy by moving object
If heat is applied to overcome reaction energy barriers, then the reaction can proceed, but the system cannot cure at ambient temperatures
Solution Approach 1:
The patent introduces a latent catalyst system that acts as an intermediary to lower the activation energy barrier for the condensation reaction. The catalyst is activated under specific conditions (such as pH change or temperature increase during application), enabling the reaction to proceed at ambient temperatures without requiring continuous external heating.
Solution Approach 2:
The coating system is formulated with pre-selected carboxyl-containing polymers and crosslinkers that are designed to react at ambient temperatures. The chemistry is chosen beforehand to have appropriate reactivity characteristics, eliminating the need for post-application heating while ensuring complete 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 system effectively forms crosslinked networks at ambient temperatures, suitable for various industrial and automotive applications, providing desirable properties without the drawbacks of isocyanate-based systems, such as health concerns and VOC generation.
Implementation Method 1
A curable composition comprising a first component with β-ketoester or malonate functional groups and a second component with aldehyde functional groups, along with a basic catalyst
Data Source
AI summary
This invention pertains to a curable composition comprising a first component having β-ketoester and/or malonate functionalities and a second component having two or more aldehyde functionalities. The compositions can be cured at room temperature or low temperatures to yield crosslinked networks that are capable of providing desirable properties for coating and adhesive applications. The reactive functionalities of β-ketoester, malonate, and aldehyde can be either on polymers as the main binders or on small molecules as the crosslinkers. The curable compositions desirably are either solventless or organic solvent based.