As an essential component of a car, car lights play an important role in night lighting, traffic signals, fog collision avoidance, turn signs, etc., and are an important guarantee for safe driving. In the production of automobile lamps, in order to seal the light distribution mirror and the lamp housing, a sealant is used for bonding.
In the application of car light bonding, first of all, the car light sealant is affected by the heat emitted by the bulb. Under the corresponding high temperature environment, its bonding and sealing performance must not change, and at the same time, it must not release organic gases and produce fog. No yellowing, which will affect the appearance; secondly, when the lamp sealant is irradiated by ultraviolet rays in the sun, there will be no aging phenomenon such as cracking of the glue layer, which requires the lamp sealant to have good UV resistance Aging performance; the rear lamp sealant will also be eroded by water vapor and rain for a long time, so it is necessary to ensure that its sealing performance will not be affected by this.
At present, the car lamp sealants used in China are mainly hot-melt butyl rubber, heat-reactive polyurethane hot-melt adhesive and silicone sealant. Car lights sealed with ordinary hot melt adhesive often have problems such as water leakage, cracks in the glue layer, poor adhesion, and fogging, which affect driving safety. Due to its unique molecular structure, silicone foam gasket products have good adhesion, excellent high and low temperature resistance, good weather resistance, good hydrophobicity, good electrical properties and chemical corrosion resistance, etc. It is widely used in the sealing of car lights.
Why choose thermally conductive silicone foam gasket?
        1. Good adhesion:
        In the production of car lights, most of the materials are plastics. The lamp housing is made of ABS, PC, PP, etc. The material of the light distribution mirror has changed from the traditional glass material to the widely used PC material. Good adhesion can ensure the airtightness of the lights and prevent the lights from falling off. If the bonding performance is not good, the lights are prone to water leakage and other adverse conditions, which will greatly reduce the service life of the lights.
        2. High temperature resistance:
        When the car is running for a long time, the headlights will always maintain a high temperature. At the same time, the high temperature will also be transmitted to the headlight sealant, which will damage the adhesiveness of the sealant and cause the headlight seal to fail. The special use environment requires the sealant to have excellent high temperature resistance. The table shows the test results of tensile strength, elongation at break and shear strength of the silicone foam gasket sample after curing at a high temperature of 150°C for 24 hours.
        3. High and low temperature cycle resistance:
        When the car is driving in a severe cold area, as the driving time increases, the ambient temperature inside the headlight rises, and the headlight sealant gradually rises from sub-zero temperature to high temperature. After the car stops driving, the temperature of the headlight sealant will slowly drop again. to outside temperature. The silicone foam gasket was subjected to a bending test after high and low temperature cycles for 300 hours, and there was no cracking, partial delamination, and bonding damage, showing good low-temperature flexibility. After 1000 hours of high and low temperature cycles, the appearance of the silicone foam gasket did not appear to be cracked or delaminated. Therefore, the silicone foam gasket with excellent high and low temperature resistance is applied to the headlights to ensure the normal operation of the headlights in high latitudes and severe low temperature regions such as Mohe, Siberia and Northern Europe.
        4. UV aging resistance:
        Cars are 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 aging resistance. Silicone foam gasket is composed of chemical molecular structure, that is, the high-energy ultraviolet rays irradiated on the earth's surface are not enough to destroy the main chain structure of silicone, so as to ensure its good ultraviolet resistance. This performance was verified by the corresponding UV resistance test. After 2000h of ultraviolet aging test, the appearance of the silicone foam gasket has no obvious change.



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