Multi-Layer Coating Film Curing for Smoothness and Luster
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Solution Overview
Problem
Existing methods for forming multi-layer coating films, particularly in the 3C1B scheme, result in impaired smoothness and brightness due to the disordering of bright pigments, especially when using water-based paints, which are less volatile and more susceptible to environmental conditions.
Innovation Solution
A method involving the simultaneous curing of four layers: a first colored coating film, a second coating film, a third colored coating film, and a clear coating film, using specific viscosity and paint solid content ranges for water-based paints to maintain smoothness and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wet-on-wet coating method is used to form multi-layer coating film, then productivity is improved by reducing baking steps, but brightness decreases due to disordered bright pigment orientation
Solution Approach 1:
The patent applies preheating treatment to the intermediate coating film before applying the base paint. This preliminary action creates a temperature gradient that controls the volatilization rate of the solvent, allowing the bright pigment to orient properly toward the clear coat direction during the wet-on-wet coating process, thus resolving the brightness degradation issue while maintaining productivity benefits
Solution Approach 2:
The patent changes the temperature parameter by implementing preheating of the intermediate coating film to a specific temperature range before applying base paint. This parameter change controls the solvent volatilization rate, enabling proper pigment orientation and brightness maintenance during simultaneous curing of multiple layers
2Ease of operation
If water-based paint is used to reduce environmental burden, then ease of operation is improved, but brightness decreases more pronouncedly due to slow water volatilization rate
Solution Approach 1:
The patent applies preheating treatment to the intermediate coating film before applying the water-based base paint. This preliminary action accelerates water volatilization control and creates optimal conditions for bright pigment orientation, resolving the brightness degradation issue specific to water-based paints while maintaining their environmental benefits
Solution Approach 2:
The patent changes the temperature parameter by implementing preheating to control the slow water volatilization rate. This parameter change enables proper pigment orientation in water-based systems, maintaining brightness while preserving the environmental advantages of water-based paints
3Illumination intensity
If intermediate coating film is baked separately before base paint application, then brightness is maintained through controlled pigment orientation, but productivity decreases due to additional baking step
Solution Approach 1:
The patent merges the base paint application and clear coat application into a simultaneous curing process. By applying base paint over preheated intermediate coating film and then applying clear coat in sequence without intermediate baking, the patent achieves both brightness maintenance through controlled pigment orientation and productivity improvement by eliminating separate baking steps
Solution Approach 2:
The patent applies preheating to the intermediate coating film as a preliminary action before base paint application. This enables the subsequent wet-on-wet coating and simultaneous curing to proceed with proper pigment orientation, achieving brightness maintenance without requiring separate intermediate baking
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 method enables the formation of a multi-layer coating film with excellent smoothness and brightness, even when using water-based paints, by controlling viscosity and paint composition to stabilize pigment orientation.
Implementation Method 1
applying an electrodeposition paint onto a steel sheet, heating and curing an applied electrodeposition paint to form a cured electrodeposited coating film
Implementation Method 2
the volatilization rate of water, which is the diluting solvent, is slow, and the volatilization rate is greatly impacted by the application environment conditions such as temperature and humidity
Implementation Method 3
heating a multi-layer coating film including the first colored coating film, the second coating film, the third colored coating film, and the clear coating film formed in steps (2) to (5) to simultaneously curing the multi-layer coating film
Data Source
AI summary
Provided is a method for forming a multi-layer coating film which makes it possible to form a multi-layer coating film which exhibits excellent smoothness and luster. The present invention forms, on a cured electrodeposited coating film formed on a stell plate, a first colored coating film comprising a first coloring coating material (P1), a second coating film comprising a second aqueous coating material (P2) having specific viscometric properties, a third colored coating film comprising a third aqueous color coating material (P3) which has a specific coating material solid content concentration (NVP3) and contains a lustrous pigment (BP3), and a clearcoat film comprising a clearcoat material (P4). The present invention simultaneously cures the formed multi-layer coating film by heating.