It is mainly suitable for water-based paints based on synthetic latex or synthetic resin emulsion. After being frozen and then thawed, there will be no harmful changes in its consistency anti-flocculation or agglomeration, and spotting, but it can maintain its original color. Performance, known as having freeze-thaw stability.
CHINA's national standard GB/T 9268-1988 "Determination of Freeze-Thaw Resistance of Latex Paint" stipulates the method for testing freeze-thaw stability. Mainly, the test samples were frozen at a temperature of 18C ± 2°C for 17 hours, then placed at 23°C ± 2 °C , and tested after 6 hours and 48 hours respectively, compared with the comparison samples stored at 23°C ± 2 °C Compared:
① Determination of viscosity (using Stormer viscometer);
②Observe and evaluate the precipitation, cementation, agglomeration, agglomeration and other conditions of the test sample in the evaluation container, expressed as " no change ", "slight" and "serious";
③ Brush the comparison sample and the test sample on the same specified test board, and after at least 24 hours of drying, visually observe and record the changes in the hiding power, gloss, condensation, spots and color of the dry paint film of the two.
US ASTM D 2243- 1995 (2003) stipulates that it should be measured after freezing at -9.4°C ± 2.8 °C for 7 days. There are also latex paint products that require multiple freeze-thaw cycles for detection methods. For example, the test of some exterior wall paints uses -5C ± 1 ℃ , 16h, and then 8h at 23°C ± 2 ℃ as a cycle. A total of 3 cycles are performed, and then the results . From a practical point of view, whether the damage of the freeze-thaw test is obvious or not depends not only on how low the temperature is and how long the time is, but also on the number of repeated freezing and thawing, that is, a reasonable cycle period.
