The so-called acid and alkali resistance test: immerse the sample in a certain concentration of acid and alkali solution for a certain period of time, and evaluate the color difference, gloss change and whether there is coating blistering and peeling off after taking it out. The acid-base test is used to evaluate the acid-base properties of the color-coated board coating.
Before the test, measure the gloss and chromaticity coordinates of the sample. Then soak the sample in 50mL/L hydrochloric acid solution or 50g/L sodium hydroxide solution for a specified time. Finally, take it out and dry it, measure the gloss and chromaticity coordinates of the sample, calculate the color difference, and evaluate the sample according to the GB/T 1766 standard for loss of gloss, discoloration, blistering, and shedding, and measure the results of parallel samples Take the worst value as the test result.
The so-called tolerance test: contact the sample with pollution for a period of time through an appropriate method, and then evaluate the color difference, gloss change, and whether there is blistering or peeling off of the coating. The pollution resistance test is mainly used to evaluate the influence of the pollutants negotiated by supply and demand on the coating of prepainted boards. Commonly used contaminants are: diluted mineral acids, acetic acid, beverages, oils and greases, shoe polish, lipstick, markers, and more. After the test, the sample can be evaluated according to the GB/T 1766-1995 standard for loss of gloss, discoloration, blistering, and shedding.
Pollution resistance tests are usually carried out with three experimental methods:
(1) Spot test (covered): Add pollutants to the surface of the sample, and immediately cover it with a watch glass. The test time is recommended to be 24 hours;
(2) Spot test (without cover): add pollutants on the surface of the sample and expose to the atmosphere. The test time is recommended to be 24 hours;
(3) Immersion test: The sample is immersed in pollutants, and the immersion time is agreed between the supplier and the buyer.
