Why is silicone sealant preferred for lamp adhesive?


Why choose silicone sealant?


1. Good adhesion


In the manufacture of car lamps, most of the materials are plastic. The manufacturing materials of lamp housing include ABS, PC, PP, etc. The manufacturing materials of light matching mirror have changed from traditional glass material to PC material which is widely used now. Good adhesion can ensure good air tightness and prevent the lamp from falling off. If the bonding performance is not good, the lamp is prone to leak and other bad conditions, which will greatly reduce the service life of the lamp.


2. High Temperature Resistance


In the long run, the lamp will keep a high temperature, at the same time, the high temperature will also be transmitted to the lamp sealant, which will destroy the adhesion of the sealant and lead to the lamp seal failure. Special usage environment requires excellent high temperature resistance of sealant.


3. High and Low Temperature Cycle Resistance


When a car is driving in a cold area, with the increase of driving time, the ambient temperature of the lamp increases, and the lamp sealant gradually climbs from low temperature below zero to high temperature. After the car stops driving, the temperature of the lamp sealant will slowly drop to the outdoor temperature. In order to test the high and low temperature resistance of silicone sealant, the experimental conditions are more stringent than the actual environment, which will accelerate the ageing of the colloid. The temperature range of high and low temperature cycle test is - 40 ~85 C, and the sampling interval is 300 h and 1000 H.


One cycle is to raise the temperature to 85 C, keep it for 20 hours, then cool it down to - 40 C, keep it for 10 hours. Silicone sealant bending test after 300 hours of high and low temperature cycling showed no cracking, partial delamination and bonding damage, which showed excellent low temperature flexibility. After 1000 hours of high and low temperature cycling, the appearance of silicone sealant did not appear cracking, delamination and other phenomena. Therefore, the silicone sealant with excellent resistance to high and low temperatures is applied to the lamp, which ensures the normal operation of the lamp in such high latitudes as Mohe, Siberia and Nordic regions with severe low temperatures.


4. Ultraviolet Aging Resistance


Automobile is used outdoors for a long time. In order to prolong the service life of the lamp, the lamp sealant needs to have excellent ultraviolet aging resistance. The main chain of the chemical molecular structure of silicone sealant is composed of Si-O-Si bond. Its chemical bond energy is 444 kJ/mol higher than 398 kJ/mol of 300 nm ultraviolet light. That is to say, the ultraviolet radiation with the highest energy on the earth surface is not enough to destroy the main chain structure of silicone and ensure its good ultraviolet resistance. The performance was verified by the corresponding anti-ultraviolet test. After 2 000 h ultraviolet aging test, the appearance of silicone sealant did not change significantly.


WH Marriott Glue from Chongqing Tianqi Industry