Surfacer and Topcoat Coating System for Wet-on-Wet Application
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Solution Overview
Problem
The existing multicoat paint systems for motor vehicles are complex and prone to errors, requiring multiple stages and flash-off times that can lead to surface defects and increased operating costs, especially when applying topcoats to substrates that have not reached the necessary dryness, compromising the quality and adhesion of the coating.
Innovation Solution
A solvent-borne coating material combination featuring a surfacer coat and topcoat with externally crosslinking binders, allowing the topcoat to be applied before the surfacer coat reaches drying stage 1, ensuring compatibility and direct 'wet-on-wet' application without forming a discrete boundary layer, thus enhancing adhesion and reducing flash-off times and potential defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the topcoat is applied before the surfacer coat reaches drying stage 1, then the flash-off time is reduced and the coating process is simplified, but the adhesion and quality of the coating may be compromised due to insufficient drying
Solution Approach 1:
The invention changes the chemical composition parameters of the coating materials. The surfacer coat contains reactive groups (isocyanate, hydroxyl, carboxyl, or amino groups) that enable chemical bonding with the topcoat applied before complete drying. This parameter change in chemical reactivity allows the topcoat to adhere properly even when applied to a partially dried surfacer coat, thus reducing flash-off time while maintaining adhesion quality.
Solution Approach 2:
The invention creates a composite coating system where the surfacer coat and topcoat are chemically compatible and can bond together. The surfacer coat is formulated with specific reactive groups that complement the topcoat composition, creating a chemically integrated multilayer structure. This composite material approach ensures that layers applied in sequence maintain strong interlayer adhesion even with reduced drying time between applications.
2Manufacturing precision
If multiple spray passes and flash-off times are used in traditional multicoat systems, then the coating quality can be maintained, but the process complexity and operating costs increase
Solution Approach 1:
The invention merges the requirements for multiple coating layers into a compatible material system where the surfacer coat and topcoat can be applied in sequence without requiring complete drying between layers. The chemical compatibility and reactive group formulation allow the combination of multiple coating functions into a streamlined process, reducing the number of separate steps while maintaining the quality that traditionally required multiple passes and extended flash-off times.
3Stability of the object's composition
If the surfacer coat is cured thermally before topcoat application, then the coating stability is improved, but the production time and energy consumption increase
Solution Approach 1:
The invention prepares the surfacer coat with reactive groups during the application stage itself, rather than requiring subsequent thermal curing to activate bonding capability. The reactive groups (isocyanate, hydroxyl, carboxyl, or amino groups) are incorporated into the surfacer formulation, enabling immediate chemical bonding with the topcoat upon application. This preliminary action eliminates the need for thermal curing between layers, reducing energy consumption while maintaining coating stability through chemical compatibility.
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 simplifies the coating process, reduces errors, and maintains the visual and mechanical properties comparable to traditional multicoat systems, while minimizing capital investment and operating costs by eliminating the need for separate application lines and reducing flash-off times.
Implementation Method 1
a coating material comprising at least one coloring pigment and comprising at least one externally crosslinking binder as main binder for forming a surfacer coat on a substrate, and of a coating material comprising at least one coloring pigment and comprising at least one externally crosslinking binder as main binder for forming a topcoat on the surfacer coat
Implementation Method 2
Following application, the resulting surfacer coat is first flashed off (flash-off time) and then cured thermally
Data Source
AI summary
Coating material combination consisting of a coating material for forming a surfacer coat and a coating material for forming a topcoat, and use thereof for producing a coating system consisting of a surfacer coat and topcoat on a substrate. The substrate preferably comprises the body or the cabin of a motor vehicle, or a constituent thereof. The coating material combination of the invention is suitable especially for producing coatings consisting of a cured surfacer coat and a cured topcoat on automobiles and commercial vehicles, such as trucks, vans, or buses.