01
Good adhesion
Most of the materials used in the manufacture of headlights are plastic. The materials for the lamp housing are ABS, PC, PP, etc. The materials used for the light mirrors have changed from traditional glass materials to PC materials that are widely used today. Good adhesion ensures the airtightness of the lights and prevents the lights from falling off. If the bonding performance is not good, the lamp is prone to water leakage and other undesirable conditions, which will greatly reduce the service life of the lamp.

The following table shows the bonding performance test of silicone sealant for several common lamp materials, showing good adhesion of silicone sealant.

02
High temperature resistance
When the car is traveling for a long time, the lamp will always maintain a high temperature, and the high temperature will also be transmitted to the lamp sealant, which will damage the adhesiveness of the sealant and cause the lamp seal to fail. The special use environment requires the sealant to have excellent high temperature resistance. The following table shows the tensile strength, elongation at break and shear strength of the silicone sealant samples after curing at 150 ° C for 24 h.

03
High and low temperature cycle
When the car is driving in a cold area, as the driving time increases, the ambient temperature of the lamp increases, and the lamp sealant gradually rises from a low temperature to a high temperature. After the car stops driving, the temperature of the lamp sealant slowly decreases. To outdoor temperature. In order to test the high and low temperature resistance of silicone sealant, the experimental conditions are more severe than the actual environment, which will accelerate the aging of the colloid. The high and low temperature cycle test temperature range is -40 ° C ~ 85 ° C, sampling interval is 300h, 1000h.

One cycle is: warming to 85 ° C, holding for 20 h, then cooling to -40 ° C for 10 h. The silicone sealant was subjected to bending test after high and low temperature circulation for 300 hours, and there was no cracking, partial delamination and adhesive damage, which showed excellent low temperature flexibility. After 1000h of high and low temperature cycle, the appearance of silicone sealant showed no cracking or delamination. Therefore, the silicone sealant with excellent high and low temperature resistance is applied to the lamp, which ensures the normal operation of the lamp in the severe low temperature areas such as Mohe, Siberia and Northern Europe.

04
UV aging resistance
The car is used outdoors for a long time. In order to ensure the longevity of the lamp, the lamp sealant needs to have excellent UV aging resistance. The main chain of the chemical molecular structure of silicone sealant is composed of Si-O-Si bond, and its chemical bond energy is 398 kJ/mol, which is 398 kJ/mol higher than 300 nm ultraviolet light, which is the highest energy ultraviolet radiation on the surface of the earth. Not enough to destroy the main chain structure of silicone to ensure its good UV resistance. This performance was verified by the corresponding UV resistance test. After 2000 h of UV aging test, the appearance of silicone sealant did not change significantly.

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