International. A recent study by Chinese and Dow Chemical researchers presented a new adsorption method to simulate the dirt collection performance of organic coatings.
Assessing the dirt resistance of organic coatings according to traditional accelerated methods (e.g. standard method GB/T 9780-2013 in China) usually provides results that deviate from their actual performance in seriously contaminated environments. As an alternative, in this work a new method of adsorption with rice straw ash modified with methyltrimethoxysilane was proposed as the standard for artificial dirt.
With this method, the ash was dispersed into the air in a test chamber and then allowed to physically adsorb the coating, which is thought to more accurately simulate the adsorption behavior of floating particles on the outside. Two groups of Dow Chemical Company latex coatings were used to evaluate the adsorption method by monitoring changes in color, whiteness and reflectivity. In parallel, outdoor exposure tests of these coatings were conducted.
The influences of the loading method, ash type and panel position on the test results were carefully investigated. The multiple ash load (9 g × 3) and the parallel panels in different positions in the test chamber are designed for the generation of repeatable results. The adsorption method was shown to basically match the outdoor exposure results and was more predictive about real-world results than the GB/T 9780-2013 standard.
Source: Journal of Coatings Technology and Research.
