Multilayer Coating Film Formed by Simultaneous Curing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The 3-coat 1-bake system using aqueous intermediate and base coating compositions in automotive body coating often results in reduced smoothness and distinctness of image due to mixed layer formation, while the intermediate coating-less system compromises on smoothness and chipping resistance.
Innovation Solution
A method involving the application of an aqueous first base coating composition, followed by an aqueous second base coating composition without preheating, and then a clear coating composition, with simultaneous curing of all three layers, utilizing specific resin compositions to control breaking energy and peel strength, resulting in a multilayer coating film with excellent smoothness, distinctness, and chipping resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a 3-coat 1-bake system using aqueous intermediate and base coating compositions is used, then energy consumption is reduced and environmental pollution is minimized, but smoothness and distinctness of image deteriorate due to mixed layer formation
Solution Approach 1:
The patent divides the base coating into two separate aqueous coating compositions (first and second base coating compositions) with different resin types and properties. This segmentation allows each layer to maintain its distinct characteristics rather than forming a mixed layer, thereby preserving smoothness and distinctness of image while still using the energy-efficient 3-coat 1-bake system with aqueous compositions
Solution Approach 2:
The patent applies local quality by giving each base coating layer specific local properties through different resin compositions. The first base coating composition contains one type of resin optimized for certain properties, while the second base coating composition contains a different resin optimized for other properties. This localized differentiation prevents unwanted mixing while maintaining overall system compatibility and performance
2Device complexity
If an intermediate coating-less system is used, then the coating process is simplified, but smoothness and chipping resistance deteriorate
Solution Approach 1:
The patent introduces an intermediate functional layer between the electrodeposition coating and the base coatings. This intermediary layer serves as a bridge that provides the necessary smoothness and chipping resistance that would otherwise require a separate intermediate coating. The layer is formed in-situ through controlled application of the first base coating composition, eliminating the need for a separate intermediate coating step while maintaining the required performance
3Reliability
If preheating is conducted after each coating application, then layer adhesion is improved, but production time increases
Solution Approach 1:
The patent merges the preheating steps into a single consolidated heating process. Instead of preheating after each individual coating application (which would require multiple separate heating cycles), the system applies all three coatings (intermediate, first base, and second base) and then performs one final simultaneous curing bake. This combining of operations maintains adequate adhesion while significantly reducing total production time
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 method forms a multilayer coating film with enhanced smoothness, distinctness of image, and chipping resistance by controlling the breaking energy and peel strength, ensuring good mechanical properties and appearance.
Implementation Method 1
three layers of the obtained multilayer coating film are simultaneously cured by heating
Data Source
AI summary
A method for forming a multilayer coating film includes applying an aqueous first base coating composition (A) onto a cured electrodeposition coating film, applying an aqueous second base coating composition (B) without preheating, performing preheating, further applying a clear coating composition (C), and simultaneously heat-curing the first base coating film, the second base coating film, and the clear coating film. The aqueous first base coating composition contains a specific aqueous polyester resin, a specific aqueous acrylic resin, a specific aqueous urethane resin and a melamine resin. A breaking energy of a coating film formed of the aqueous first base coating composition and a peel strength between the coating film and the cured electrodeposition coating film are controlled to specific values.