Thio-Michael Addition Coating Composition for Automotive Clear Coat
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Solution Overview
Problem
Conventional clear coating systems for automotive paint, particularly in multilayer paint systems, face challenges such as high energy consumption, long processing times, and the use of toxic crosslinkers like melamine and isocyanates, which affect storage stability, cost, and environmental impact.
Innovation Solution
A curable coating composition comprising a Michael donor with thiol groups, a Michael acceptor, and a specific catalyst, formulated to avoid melamine and isocyanate crosslinkers, ensuring high chemical resistance, hardness, and adhesion, while allowing for lower processing temperatures and reduced energy use, with a kit-of-parts design for efficient application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clear coating systems use melamine and isocyanate crosslinkers, then high chemical resistance and hardness are achieved, but toxic substances are released and storage stability deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system by replacing melamine and isocyanate crosslinkers with a Michael donor-acceptor system involving thiol groups and unsaturated compounds. This substitution maintains crosslinking capability while eliminating toxic substance release, achieving both high chemical resistance and environmental compatibility.
Solution Approach 2:
The patent converts the potentially harmful effect of rapid crosslinking (which causes surface defects) into a beneficial controlled reaction by using a catalyst system that enables crosslinking at lower temperatures without releasing toxic substances. The Michael addition reaction provides a clean crosslinking mechanism that achieves the desired mechanical properties without the harmful by-products of conventional systems.
2Reliability
If high temperature curing is used, then complete crosslinking is achieved, but energy consumption increases and processing time extends
Solution Approach 1:
The patent changes the temperature parameter of the curing process by introducing a catalyst system that enables the Michael addition reaction to proceed at lower temperatures. This parameter change reduces energy consumption while maintaining complete crosslinking, as the catalyzed reaction pathway has lower activation energy requirements compared to thermal curing alone.
Solution Approach 2:
The patent introduces a catalyst as an intermediary substance that mediates the crosslinking reaction between Michael donors and acceptors. This catalyst enables the reaction to proceed at lower temperatures by providing an alternative reaction pathway with lower activation energy, thereby reducing the energy input required for complete crosslinking while maintaining curing effectiveness.
3Productivity
If strong base catalysts are used, then crosslinking rate increases, but reaction control becomes difficult and surface defects occur
Solution Approach 1:
The patent changes the catalyst parameter from strong bases to a specific catalyst system comprising a metal salt and organic compound. This parameter change provides better control over the crosslinking reaction rate, preventing excessive reaction speed that causes surface defects while maintaining adequate productivity. The new catalyst system allows for more precise control of the Michael addition reaction.
Solution Approach 2:
The patent introduces a specific catalyst system as an intermediary that mediates the crosslinking reaction with better control characteristics. This catalyst system acts as a controlled mediator that enables the reaction to proceed at an optimal rate without the runaway reactions associated with strong base catalysts, thereby maintaining both productivity and surface quality.
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 coatings with high gloss, excellent mechanical properties, and improved processing stability, eliminating the use of toxic substances and reducing energy and time requirements, making it suitable for OEM and refinish applications.
Implementation Method 1
a curable coating composition comprising at least one Michael donor (A) having at least one thiol group, at least one Michael acceptor (B) and at least one specific catalyst (C)
Implementation Method 2
at least one specific catalyst (C)... the use of specific salts of carboxylic acids as catalyst in a reaction between a Michael donor (A) having at least one thiol group and a Michael acceptor (B)
Data Source
AI summary
The present invention relates to a curable coating composition comprising at least one Michael donor (A) having at least one thiol group, at least one Michael acceptor (B) and at least one specific catalyst (C), its use as a clear coating in a method to prepare a multilayer coating and a multilayer coating obtained from said process. Moreover, the present invention relates to a kit-of-parts comprising at least two separate containers C1 and C2, wherein the specific catalyst (C) is contained in container C1 and/or C2, preferably in container C1. Finally, the present invention relates to the use of specific salts of carboxylic acids as catalyst in a reaction between a Michael donor (A) having at least one thiol group and a Michael acceptor (B).