Multilayer Red Coating Film with Controlled Hue Angles

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Solution Overview

Problem

Existing methods for forming red-based metallic paint coatings struggle to achieve high chroma, depth, and weatherability while maintaining application workability and controlling film thickness.

Innovation Solution

A method involving the sequential application of a first colored coating composition with organic red pigments to create a specific hue, followed by a second colored coating composition, and then a clear coating composition, all within precise hue and chroma ranges in the L*C*h color space, to form a multilayer coating film with controlled color difference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a metallic base coating composition, a second base coating composition having transmittance, and a clear coating composition are applied sequentially, then a metallic paint color with high chroma can be achieved, but the coating line is difficult to control and weather resistance is insufficient

Engineering Contradiction:
ImprovechromaVSAvoidcoating line control
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent divides the coating process into three distinct layers with specific functions: a base coating layer for adhesion and substrate coverage, an intermediate coating layer containing transmittance control agents for chroma enhancement without requiring precise thickness control, and a clear coating layer for weather protection. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between achieving high chroma and maintaining coating line control.

Inventive Principle:
Principle #1Segmentation

2Illumination intensity

If a second base coating composition having transmittance is used to achieve high chroma, then chroma is improved, but weather resistance becomes insufficient

Engineering Contradiction:
ImprovechromaVSAvoidweather resistance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies local quality by giving each coating layer specific properties tailored to its function: the base coating layer provides adhesion and coverage, the intermediate layer contains transmittance control agents (such as iron oxide or titanium dioxide) specifically for chroma enhancement, and the clear coating layer is formulated with weather-resistant resins and UV absorbers for protection. This localized functional differentiation allows the system to achieve both high chroma and weather resistance simultaneously.

Inventive Principle:
Principle #3Local quality

3Illumination intensity

If a 4C2B process is used to form a multilayer coating film, then chroma and appearance can be improved, but productivity decreases due to the number of steps

Engineering Contradiction:
ImprovechromaVSAvoidproductivity
Core Design Contradiction:
Illumination intensityVSProductivity

Solution Approach 1:

The patent merges the functions of multiple coating layers into a streamlined 3-layer system that achieves the same chroma and appearance effects as more complex processes. By combining adhesion, chroma enhancement, and weather protection functions into three integrated layers with clear functional boundaries, the patent reduces the number of processing steps while maintaining high chroma output, thereby improving productivity without sacrificing quality.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentUS10239091B2Method for forming multilayer coating film
Publication Date: 2019.03.26 KANSAI PAINT CO LTD

AI summary

The problem to be solved by the present invention is to provide a method for forming a multilayer coating film capable of forming a red-based multilayer coating film having high chroma and an excellent sense of depth and weatherability. The present invention provides a method for forming a multilayer coating film comprising the steps of (1) applying a first colored coating composition comprising an organic red pigment to form a first colored coating film having a hue such that the hue angle h in the L*C*h color space diagram is within the range of 23±3°, (2) applying a second colored coating composition comprising an organic red pigment to the first colored coating film to form a second colored coating film having a hue such that the hue angle h in L*C*h color space diagram is within the range of 35±5°, and (3) applying a clear coating composition to the second colored coating film to form a clear coating film; wherein the color difference ΔE between the first colored coating film and the multilayer coating film obtained by Steps (1) to (3) is within the range of 20 to 30.