Preparation Of Condensed Two-component RTV High-strength And Low-dielectric Constant Silicone Adhesive

The condensed room temperature vulcanized liquid silicone adhesive,also known as room temperature vulcanized silicone rubber is widely used in the fields of automotive,electronics,aerospace and medicine,etc.,because of its special material structure which gives it many excellent performances,such as high and low temperature resistance,weather resistance,UV and ozone aging resistance,insulation and chemical stability,etc.However,the current study on the condensed vulcanized silicone rubber always focuses on the meeting the requirement of mechanical properties,which leads to a decline of dielectric properties,and that limits its application in the fields of microelectronics and aviation.In order to overcome this shortcoming,a silicone rubber with high strength and low dielectric constant is prepared through the studies on the structure of silicone raw material,the choice of molecular weight,the development of new crosslinking agent,the accelerator,the composition of filler and the surface treatment method.In this paper,the technology research and development of dealcoholized room temperature curing silicone rubber is used to synthesize the room temperature curing silicone adhesives with high strength and low dielectric constant.The dealcoholized room temperature curing silicone rubber is a kind of condensed room temperature vulcanized silicone rubber;its condensation reaction products are alcohol small molecules with non-toxic and pollution-free features,therefore it has an extensive prospect.Through the comparison of processing properties between titanium-based and organotin-based catalyst systems,the latter is chosen as the main catalyst system with107 silicone rubbers as the base polymer.The crosslinking system is confirmed through the analysis of mechanical properties and dielectric constant of silicone rubber crosslinked with traditional crosslinking agent and self-made crosslinking agentrespectively,and it is a combination of tetraethoxysilane(TEOS)and self-made crosslinking agent.The effects of the molecular weight of 107 silicone rubbers,the type and amount of crosslinking agent and the amount of reinforcing resin on the strength and dielectric constant of silicone rubber are investigated.And the optimal amounts of each component are confirmed by the analysis from the aspects of mechanical,dielectric and processing properties.The experimental results show that the self-made cross-linking agent in combination with TEOS will obtain better mechanical properties and relatively low dielectric constant;and the operation time and tack-free time of silicone rubber can be adjusted through changing the ratio of the two crosslinking agents;the mechanical properties of silicone rubber also can be improved to a certain degree by mixing the 107 silicone rubbers with low and high molecular in proportion to be used as the base polymer;the addition of methyl MQ resin shows a significant reinforcement effect on the silicone rubber,but it will lead to an increase in dielectric constant.The effect of selection and surface treatment of reinforcing filler on the mechanical properties and dielectric constant of silicone rubber are significant.In this paper,the selection,proportion and surface treatment of filler is studied in depth.The effect of the surface treating agents on the properties of the silicone rubber is compared with the main reinforcing filler white carbon black and semi-reinforcing filler diatomite using in combination.And it is determined that the self-made treating agent should be used as the filler surface treating agent,which will improve the mechanical properties and the lower the dielectric constant.And the hot air aging and the TG test shows that the heat resistance of cured silicone rubber also has an obvious improvement.