Determination of moisture and heat resistance of paint film (GB/T1740-89) This standard is applicable to the determination of moisture and heat resistance of paint film, using a temperature and humidity control box. Control a certain temperature, humidity and time to conduct the test. The grade is evaluated based on the degree of damage to the appearance of the model.
(1) Materials and equipment
Temperature and humidity control box.
Transparent plexiglass plate 70mmx150mx(0.5~2)mm. Divide into 100 equal parts.
(2) Measurement method
According to the product standard, the base material and supporting base material are selected, and it is made according to the "methods of paint aging for the determination of moisture resistance, salt spray resistance, and weather resistance (artificial acceleration)" (GB/T1765).
Before testing, record the original state of the sample. Then hang the model vertically on the model frame, and the front of the model does not touch the ship. Put it into a temperature-adjusting and humidity-conditioning box pre-adjusted to a temperature of 47°C ± 1°C and a relative humidity of 96% ± 2%. When it returns to the specified temperature and humidity, start to calculate the test time. There should be no suspected exposure on the surface of the sample during the test. Check once in 48 hours of continuous testing. After two checks, check every 72 hours. After each inspection, the samples shall be repositioned. The last inspection shall be carried out according to the number of hours specified in the technical product standards; if there is no product standard, the inspection time may be determined according to the specific circumstances.
(3) Sample inspection and rating inspection
It is necessary to avoid fingerprints on the surface of the model, and compare it with the standard under sufficient light or direct light, and the result shall be based on the two of the three boards with the same level. The moisture and heat resistance of the paint film is evaluated according to Table 10-4.
