Wet Coating Tint Strength Prediction via Reflectance
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Solution Overview
Problem
Current methods for predicting tint strength in paint manufacturing are time-consuming, cumbersome, and lack sensitivity, leading to inconsistent batch quality due to reliance on visual observation and insensitive tools like the Hegman grind gage.
Innovation Solution
A process that correlates the gloss of a wet coating layer's reflectance to its tint strength, using a device with a rotating test substrate, optical measurement, and a computerized system to create a tint strength prediction curve, allowing real-time adjustments during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual observation methods like Hegman grind gage are used to measure tint strength, then the measurement process is simple to perform, but the measurement precision and sensitivity are insufficient leading to batch-to-batch quality variations
Solution Approach 1:
The patent replaces the mechanical Hegman grind gage system with an optical measurement system using a spectrophotometer. The system measures the reflectance spectrum of the coating at multiple wavelengths (400-700nm) and uses computational algorithms to calculate tint strength, eliminating the need for visual observation and mechanical grooves while dramatically improving measurement precision and objectivity.
Solution Approach 2:
The patent introduces a spectrophotometer as an intermediary device between the coating sample and the measurement process. This device objectively captures the reflectance spectrum and serves as a mediator that translates physical coating properties into quantifiable spectral data, which is then processed through algorithms to determine tint strength, thereby eliminating subjectivity in visual observation.
2Productivity
If traditional testing procedures are used to check tint strength, then the process is easy to operate, but the productivity is reduced due to time-consuming manual testing and adjustments
Solution Approach 1:
The patent implements continuous real-time measurement during the coating manufacturing process. The spectrophotometer continuously monitors the reflectance spectrum as the coating is being applied and cured, allowing for immediate detection of tint strength deviations and continuous adjustment, thereby eliminating the discontinuous batch-testing approach and maximizing productivity.
Solution Approach 2:
The patent establishes a closed-loop feedback system where the measured reflectance spectrum is immediately processed to calculate tint strength, compared against target values, and used to generate real-time control signals for adjusting the coating process. This rapid feedback loop enables immediate corrections and eliminates the time delay inherent in traditional batch testing and manual adjustment procedures.
3Manufacturing precision
If extended grinding time is used to improve pigment dispersion, then the tint strength is improved, but the manufacturing time increases and metallic flake size is reduced
Solution Approach 1:
The patent applies preliminary action by measuring the reflectance spectrum and calculating tint strength during the grinding process itself, before the grinding is complete. This allows for prediction of the final tint strength at intermediate grinding stages, enabling the process to be stopped at the optimal point when desired tint strength is achieved, thereby avoiding unnecessary extended grinding time and preserving metallic flake size.
Solution Approach 2:
The patent replaces the mechanical trial-and-error grinding approach with an optical measurement and computational prediction system. The spectrophotometer measures the evolving reflectance spectrum during grinding, and algorithms predict the final tint strength, allowing for precise control of grinding duration without relying on extended mechanical grinding to ensure adequate dispersion.
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
Enables accurate and timely prediction of tint strength, reducing batch-to-batch variations and allowing for immediate process adjustments to achieve desired tint qualities in automotive OEM and refinish paints.
Implementation Method 1
a beam of light at a preset intensity and at a preset angle of incidence is projected on a measurement area of the wet layer and a value of reflectance of the beam of light reflected from the wet layer at a preset angle of reflectance is measured
Data Source
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AI summary
The present invention is directed to a process for predicting the tint strength of a pigmented coating composition, such as automotive OEM or refinish paint, on a real time basis while it is being made. Generally, tint strength can be improved by controlling the grinding time during the manufacturing process. The process includes measuring reflectance (a-value) of a wet layer of the coating composition applied over a test substrate by using tint strength prediction device of the present invention. The tint strength of a coating resulting from a layer, obtained by adding a reference binder to the coating composition, is then measured. The process is repeated by subjecting the coating compositions to successive grinding intervals. The tint strength vs. reflectance is plotted on a graph and then by using a curve fitting equation, a tint strength prediction curve is obtained. By measuring the reflectance of a wet layer of a target coating composition, the tint strength of that target coating composition can then be predicted by using the tint strength prediction curve. The process is most useful during the manufacture of coating compositions, such as automotive OEM and refinishes paints.