As an indispensable component of a car, car lights play an important role in night lighting, driving signals, fog collision avoidance, turn signs, etc., and are an important guarantee for car safety. In the manufacture of automobile lights, in order to seal the lens and the lamp housing, sealant must be used for bonding.
The currently used car lamp sealants are mainly hot-melt butyl glue, heat-reactive polyurethane hot-melt glue and silicone sealant. Car lights sealed with ordinary hot melt adhesives often have problems such as water leakage, cracking of the glue layer, poor adhesion, and fogging, which affect driving safety. Due to its unique molecular structure, silicone sealant products have the characteristics of good adhesion, excellent high and low temperature resistance, excellent weather resistance, good water repellency, excellent electrical properties and chemical resistance. The silicone sealant is widely used in car lamp sealing.
1. Good adhesion
In the production of car lights, most of the materials are plastic. The lamp housing is made of ABS, PC, PP, etc. The material of the light distribution lens has changed from the traditional glass material to the widely used PC material. The good adhesion of the silicone sealant can ensure the air tightness of the car lights and prevent the car lights from falling off.
2. 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, destroying the adhesiveness of the sealant, and causing the lamp seal to fail. The special use environment requires the sealant to have excellent high temperature resistance. The silicone sealant will not lose its adhesiveness and elasticity under high temperature conditions, and it can still play a very good sealing and waterproof role.
3. Resistance to high and low temperature cycles
After testing, the silicone sealant was subjected to a bending test after a high and low temperature cycle for 300 hours, and there was no cracking, partial delamination, and bonding damage, showing excellent low temperature flexibility. After 1000 hours of high and low temperature cycles, the appearance of the silicone sealant did not show cracks or delamination. Therefore, the silicone sealant with excellent high and low temperature resistance is applied to car lights to ensure the normal operation of car lights in high latitude and severe low temperature areas such as Mohe, Siberia and Northern Europe.
4. UV aging resistance
The car is used outdoors for a long time. In order to ensure that the service life of the lamp can be extended, the lamp sealant needs to have excellent UV resistance. The main chain of the chemical molecular structure of silicone sealant is entirely composed of Si-O-Si bonds, and its chemical bond energy is 444 kJ/mol. The energy is higher than 300nm ultraviolet light, that is, the ultraviolet light with the highest energy irradiated to the earth's surface is not enough to break the main chain structure of organosilicon, thus ensuring its good UV resistance.