Multilayer Coating Film Structure for Automotive Color Uniformity
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Solution Overview
Problem
In automotive body coating, the omission of an intermediate coating film to reduce process steps and costs leads to uneven hue due to paint dust adhesion, causing visual discrepancies between inner and outer plate portions when using two-layer base coatings with different light interception characteristics.
Innovation Solution
A multilayer coating film structure where the spectral reflectance ratio of the first layer to the second layer is controlled within specific ranges to ensure a target color is achieved, preventing visual discrepancies by matching the hue of the inner and outer plate portions, even when paint dust adheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an intermediate coating film is omitted to simplify the process and reduce costs, then productivity and cost are improved, but manufacturing precision deteriorates due to uneven hue and visual discrepancies
Solution Approach 1:
The base coating is divided into two distinct layers: a first base coating film applied to the inner plate portion, and a second base coating film applied to the outer plate portions. This segmentation allows each layer to be optimized for its specific function - the first layer provides light interception characteristics while the second layer provides color characteristics, eliminating the need for an intermediate coating film and maintaining color uniformity across different body portions.
Solution Approach 2:
Different coating formulations are applied to different locations: the first base coating film contains light interception pigments (mica, aluminum powder) for the inner plate portion, while the second base coating film contains color pigments for the outer plate portions. This local differentiation of coating properties ensures that each area receives the appropriate functional characteristics without requiring an intermediate protective layer.
2Ease of operation
If paint dust adhesion is not controlled during coating, then ease of operation is improved, but manufacturing precision deteriorates due to hue differences in shaded portions
Solution Approach 1:
The patent acknowledges that paint dust will adhere to the first base coating film during the coating of outer plate portions, but converts this harmful effect into a beneficial one by designing the first base coating film with light interception characteristics (using mica, aluminum powder, or titanium dioxide). These pigments mask the paint dust, making it invisible or less noticeable, thereby maintaining hue consistency without requiring complex dust control measures.
3Reliability
If light interception characteristics are imparted to the first base coating film, then reliability is improved by protecting from ultraviolet rays, but device complexity increases due to multiple coating layers
Solution Approach 1:
The patent merges the functions of light interception and base coating into a single first base coating film layer. This layer simultaneously provides ultraviolet protection through light interception pigments (mica, aluminum powder, or titanium dioxide) and serves as the foundational coating layer. By combining these functions in one layer rather than separating them into multiple layers, the coating structure remains simple while maintaining reliability.
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 controlled spectral reflectance ratio ensures a uniform color appearance on the automotive body by minimizing the impact of paint dust adhesion, maintaining desired color and light interception characteristics.
Implementation Method 1
light interception characteristics are imparted to the first base coating film
Implementation Method 2
a ratio (1BC)/(1BC+2BC) of a spectral reflectance (1BC) of a color of the first layer to a spectral reflectance (1BC+2BC) of the target color
Data Source
AI summary
A double-structure coated object includes an outer plate portion configured to produce a target color by stacking a coating film of a first paint and a coating film of a second paint, and an inner plate portion on which a coating film of the second paint is formed. When the coating film is formed on the inner plate portion, and then the first paint and the second paint are sequentially applied to the outer plate portion, paint dust on the inner plate portion is prevented from causing viewers to feel something different about color. To achieve this, the ratio (1BC)/(1BC+2BC) of the spectral reflectance (1BC) of the color of the coating film made of the first paint to the spectral reflectance (1BC+2BC) of the target color is configured to fall within a predetermined range.