Coating System Adhesion Promoter for Sealant Bonding
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Solution Overview
Problem
Existing coating systems for bonding glass to vehicle bodies face challenges in achieving threshold adhesion strength while maintaining aesthetic quality, especially with below-specification film builds and low-temperature curing, often requiring manual application of reactive primers and additives that can negatively impact appearance and safety performance.
Innovation Solution
A coating system comprising a clear coat layer formed from a crosslinkable carbamate-based resin and an aminoplast, with an optional sub-clear coat layer and tie coat layer, incorporating an adhesion promoter like isocyanate hydrolysis retarder and accelerator to enhance adhesion between the clear coat and sealant, reducing the need for additives in the clear coat composition and allowing for low-temperature curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additives or modifications are added to the clear coat resin to maximize adhesion strength, then adhesion strength is improved, but aesthetic qualities of the clear coat layer deteriorate
Solution Approach 1:
A tie coat layer is introduced as an intermediary between the clear coat layer and the sealant. This tie coat contains adhesion promoters (isocyanate hydrolysis retarder and accelerator) that enhance adhesion strength, while the clear coat layer itself remains free of these additives, preserving its aesthetic qualities. The tie coat acts as a mediator that provides the necessary adhesion functionality without compromising the appearance of the clear coat.
2Strength
If high amounts of additives are added to the resin to enable threshold adhesion strength for below-specification film builds, then adhesion strength is improved, but detrimental effects to aesthetic qualities are magnified
Solution Approach 1:
The coating system is segmented into distinct functional layers: the clear coat layer (for aesthetics) and the tie coat layer (for adhesion). By placing the adhesion promoters specifically in the tie coat layer rather than mixing them throughout the clear coat, the system achieves the necessary adhesion strength even for below-specification film builds while keeping the clear coat layer free of additives that would harm its appearance.
3Strength
If manual application of reactive primer or tape masking is used to achieve adhesion strength, then adhesion strength is improved, but process complexity and labor requirements increase
Solution Approach 1:
The coating system is formulated to be self-sufficient for achieving adhesion strength. The tie coat layer contains built-in adhesion promoters (isocyanate hydrolysis retarder and accelerator) that automatically provide the necessary bonding capability without requiring manual application of reactive primers or tape masking operations. The system self-regulates the adhesion promotion through the chemical composition of the tie coat.
4Duration of action of stationary object
If crosslinkable carbamate-functional polymers are used to provide resistance to environmental etching, then durability is improved, but adhesion strength may be compromised
Solution Approach 1:
The system segments the functionality between layers: the clear coat layer uses crosslinkable carbamate-functional polymers for durability and environmental resistance, while the separate tie coat layer provides adhesion promotion through isocyanate hydrolysis retarder and accelerator. This segmentation allows both durability and adhesion strength to be optimized in their respective layers without compromise.
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 coating system achieves threshold adhesion strength according to MVSS standards without detrimental effects on aesthetic qualities, even with below-specification film builds, and eliminates the need for manual application of reactive primers, enhancing process efficiency and safety.
Implementation Method 1
adhesion strength between the sealant and the clear coat layer... adhesion promoter is present in the clear coat composition... adhesion promoter is present in at least one of the sub-clear coat composition and/or the tie coat composition, when the sub-clear coat layer and/or tie coat layer are present in the coating system, in an amount sufficient to increase adhesion between the clear coat layer and the sealant
Implementation Method 2
clear coat layer formed from a clear coat composition that comprises a crosslinkable carbamate-based resin and an aminoplast
Implementation Method 3
sealant is formed from a sealant composition that comprises an isocyanate component and an isocyanate-reactive component
Data Source
AI summary
A coating system includes a clear coat layer and a sealant. The clear coat layer is formed from a clear coat composition that comprises a crosslinkable carbamate-functional resin and an aminoplast. Optionally, the coating system further includes a sub-clear coat layer. The sealant is bonded to the clear coat layer opposite the sub-clear coat layer. Optionally, the coating system further includes a tie coat layer and that is disposed between the sealant and the clear coat layer. An adhesion promoter is present in the clear coat composition in an amount of less than or equal to about 3% by weight based on the total weight of resin solids of the clear coat composition. Further, the adhesion promoter is present in at least one of the sub-clear coat composition and the tie coat composition in an amount sufficient to increase adhesion between the clear coat layer and the sealant.