Because the sealing strip is used under severe conditions, the material properties determine the service life of the product. In particular, the climate is extremely demanding. In order to ensure the normal operation of the seal under these conditions, the specifications and performance of the coach usually have the following items:
A. Resistance to ozone and air
This is because the working environment of the car has been in all weather conditions for a long time (rain, snow, frost, and sun), so it is required that the sealing strip maintain certain performance requirements and necessary service life under various environments, and all materials must have good aging resistance.
B. Hardness, tensile strength, elongation at break
The basic performance requirements of these materials usually have two sets of performance requirements for their supply status and hot air. According to the use state, the operating temperature range of the car is -40 ℃ -70 ℃. The hot air aging temperature is generally chosen to be 70 ° C.
C. High temperature performance
Because the temperature range of the sealing strip is between -40 ° C and 70 ° C (the cabin may reach 120 ° C). EPDM rubber (classified by propylene content) and its vulcanizate properties directly affect the low-temperature elasticity of the sealing strip. In order to maintain good elasticity at low temperatures, this performance is often used as a regular performance.
D. Compression set
This is because the sealing strip uses the high elasticity of its material and the contact pressure generated between the coupling body mainly composed of the vehicle body to realize the sealing strip for the medium. Physicochemical changes occur in the rubber under compression, and when the compression disappears. These changes prevent the material from returning to its original state, which results in compressive permanent deformation. Therefore, compressive permanent deformation is an important indicator of the performance of the sealing strip material.
E. Paint resistance
This is because the sealing strip is directly installed on the car body, and the internal components migrate to the car paint after the rubber is vulcanized. In direct contact with the car body paint board, the substances released by each component in the paint under various environments will interact with the weather strip, accelerate aging, and reduce its performance. Therefore, the paint resistance is also an important conventional performance of the weather strip.