Coated Metal Sheet Chipping Resistance Low Temperature
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Solution Overview
Problem
Current automobile body coating systems require a chipping primer to provide chipping resistance, which increases production costs and complexity, and existing solutions do not effectively omit the chipping primer while maintaining chipping resistance, especially in low-temperature environments.
Innovation Solution
A coated metal sheet with a coating film comprising an organic resin, electrically conductive pigments, and anti-corrosion pigments, where the organic resin has a glass transition temperature of -80° C. to -20° C. and specific Martens micro-hardness values, providing inherent chipping resistance without the need for a chipping primer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aqueous chipping primer with low glass transition temperature is used to provide chipping resistance, then chipping resistance is improved, but the coating process complexity and production cost increase
Solution Approach 1:
The patent combines the functions of the electrodeposition coating and the chipping primer into a single integrated coating layer. This unified coating structure provides both corrosion protection and chipping resistance without requiring a separate chipping primer application step, thereby simplifying the coating process while maintaining chipping resistance
Solution Approach 2:
The patent creates a multi-functional coating layer that simultaneously performs multiple functions: corrosion protection (through electrochemical properties), chipping resistance (through low glass transition temperature and elasticity), and adhesion to the metal substrate. This eliminates the need for separate specialized layers for each function
2Reliability
If an intermediate coating layer with rubber particles is used to provide chipping resistance, then chipping resistance is improved, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent merges the chipping resistance function into the electrodeposition coating layer itself by incorporating elastomeric polymers with low glass transition temperature. This eliminates the need for a separate intermediate coating layer with rubber particles, reducing both material costs and manufacturing complexity while maintaining chipping resistance
3Reliability
If a coating film with high elasticity and large extension rate is used to mitigate stone impact, then chipping resistance is improved, but adhesion to metal substrate may be compromised
Solution Approach 1:
The patent creates a composite coating system combining electrochemical components (for adhesion and corrosion protection) with elastomeric polymer components (for chipping resistance). The electrochemical basis weight provides strong substrate adhesion through electrochemical bonding, while the elastomeric polymers with low glass transition temperature provide flexibility and impact absorption, achieving both adhesion and chipping resistance simultaneously
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 coated metal sheet achieves effective chipping resistance and corrosion protection in low-temperature environments, eliminating the need for a chipping primer and simplifying the coating process, while preventing adhesion issues during storage and handling.
Implementation Method 1
the properties of the chipping primer, a high elasticity of the coating film, a large rate of extension of the coating film, and a high strength of the coating film are required
Implementation Method 2
the coating film is exposed to low temperatures, and is affected by internal stress that is prone to contract
Data Source
AI summary
Provided is a coated metal sheet for automobile comprising: a metal sheet; and a coating film (α) present on at least one surface of the metal sheet. The coating film (α) contains an organic resin (A), an electrically conductive pigments (B), and anti-corrosion pigments (C), and a Martens micro-hardness HM at −20° C. of the surface of the coating film (α) is 10 to 200 (mg/mm2) at 20 points or more when measured at 100 points, and a Martens micro-hardness HM at 40° C. of the surface of the coating film (α) is 200 to 200,000 (mg/mm2) at 5 points or more when measured at 100 points.