Resistance to cold and hot temperature difference refers to the ability of paint film to resist damage in the process of temperature change from low to high or from high to low. According to the national standard GB4893.7-85, paint film is resistant to cold and hot temperature difference performance measurement method is as follows:

1. Equipment and materials: constant temperature and humidity box (temperature higher than 60℃, relative humidity 98% ~ 99%), low temperature refrigerator (temperature lower than -40℃), balance, electric stove, magnifying glass, bristling brush, paraffin and rosene, etc.

The determination method of resistance to cold and hot temperature difference is illustrated in Figure 1

Method for determination of resistance to hot and cold temperature differences

2. Testing steps:

Four samples were taken, one of which was used as a comparison model and the remaining three as tests. A mixture of paraffin and rosin (1:1 ratio) was used to seal the periphery and back of the specimen.

Put the closed sample into a constant temperature and humidity box (temperature 40±2℃, humidity 98% ~ 99%) and keep it for 1 hour.

The samples were removed and immediately placed in a low temperature refrigerator (temperature -20±2℃) for 1 hour.

The above temperature change steps were repeated, and after every three cycles, the samples were placed in an environment of 20±2 ° C and 60% ~ 70% relative humidity for 18 hours.

Observe sample, use 4 times the magnifying glass to observe any crack, bubble, obvious loss of light and color, and so on and so forth.

Method for determination of resistance to hot and cold temperature differences

According to the agreement between the supply and demand parties, different cycles can be selected, such as 3, 6, 9, 12, 15, 18 weeks, etc.

If cracks, bubbling, significant loss of light, discoloration, etc. occur during the inspection process, the sample is judged to be unqualified.

The test of temperature difference between cold and hot can simulate the performance of the paint film under temperature change, help to evaluate the stability and durability of the paint film, and ensure that the paint film will not be damaged or quality problems under different temperature conditions.