Test Plan: Place the sample in the thermal shock test chamber. First, keep it at a low temperature of –40℃±2℃ for 1 hour; then change to a high temperature of 70℃±2℃ within 1 minute and keep it for 1 hour. Do 24 cycles in total (48 hours). Check the product appearance and paint adhesion after the test is complete.
Result Criteria: The coating shall be qualified if there are no cracks, blisters, or peeling of paint and if the adhesion test is above 3B without complete detachment.