The heat resistance of paint film refers to the ability of paint film to resist discoloration, softening and bubbling when it is heated. According to the national standards GB489.2 and GB4893.3, the heat resistance of paint film is divided into dry heat resistance and wet heat resistance. The following is the determination of heat resistance of paint film:

1. Determination of moisture and heat resistance of paint film:

Equipment and material: brass copper cup, electric furnace, balance, crucible tongs, thermometer, insulation pads, nylon shioze, stainless steel pointed tweezers, distilled water, heating medium, watch boxes, etc.

Test conditions: laboratory temperature of 20±2℃, relative humidity of 60% ~ 70%. The test temperature is selected in the range of 55 ° C, 70 ° C and 85 ° C according to the product standard or protocol.

Method for determination of heat resistance of paint films

Detection procedure: Select three detection areas with a diameter of 50mm on the sample, and record the color, gloss and surface condition of the paint film of the area. And then into a specific temperature in the copper try a cup of mineral oil, heated to the required temperature, then will try a cup on the detection area, try a cup with sample with nylon shioze soaked with distilled water. After standing for 15 minutes, remove the test cup and nylon spin and blot the liquid from the surface. Let stand for 16 ~ 24 hours later, observe the detection area impressions, discoloration, bubbling, and so on and so forth, according to the classification standard for evaluation.

2. Determination of dry heat resistance of paint film:

Equipment and materials: the same as the heat and moisture resistance method.

Test procedure: Test temperature is selected between 70℃, 80℃, 90℃, 100℃ and 120℃. The testing procedure is roughly the same as the damp-heat resistance method, except that no wet nylon spinning is placed between the copper test cup and the sample. Finally in observing the natural light in the cabinet, the change of the sample, according to the classification standard for evaluation.

Method for determination of heat resistance of paint films

Paint film of the heat resistance test can help assess the performance of coating in high temperature environment, so as to determine its applicability and durability. According to different product standards or requirements, different test temperatures can be selected, and the performance of the paint film can be evaluated according to the grading standards.