| As the reinforcing fillers for addition type silicone rubber, MQ silicone resin had no obvious effect on the viscosity of silicone oil, and almost no damage to the trans-parency of the cured silicone rubber. With the development of electronic packaging industry, silicone resins with higher performance especially their higher refractive in-dex have been required.. However, the most available products for current packaging industry are mainly methyl vinyl silicone resins, the technique for preparing high re-fractive index silicone resins was almost monopolized by foreign companies. Conse-quently, it is very stringent to conduct research on silicone resins with higher refrac-tive index.The refractive index of silicone resin is directly related to its structure. According to related reports, there is a good linear relationship between the refractive index and the phenyl content the organosilicon polymer contains, namely, the refractive index increases with the phenyl content. Currently, the end-capping agents containing phe-nyl group are mostly composited by single-phenyl silanes or diphenylsilanes, and in most of these end-capping agents, there is no active group contained. In order to take part in the hydrosilylation reaction, vinyl group containing silanes had to be used. The value of M/Q ratio is one of the important parameters for MQ type silicone resins. The most suitable range for MQ silicone resin is among 0.6 and 1.0 since MQ resins in this range could exhibit ideal application features. Although the addition of vinyl group is beneficial to enhance the crosslinking process for silicone resins, however, the moiety of phenyl group decreased with the increase of vinyl contained silanes and thus limit the increase of refractive index for MQ resins.Based on this, a research on modification of the end-capping agents for MQ res-ins was carried out in this thesis. A novel silane end-capping agent containing both phenyl and vinyl group was synthesized, and its structure was confirmed through an-alytical method such as FT-IR, GC-MS and NMR. Silicone resins end-capped with this novel silane were synthesized and their properties were studied. This thesis is consisted of the following chapters.In chapter 1, the advances in preparation of MQ silicone resins were briefly re-viewed and problems existed in preparation of high refractive index silicone resins had been analyzed. The research goal and the technical route of this thesis were pro-posed subsequently.In chapter 2, dimethylphenylethoxysilane was prepared by Wurtz-Fitting reaction, and then purified by vacuum distillation method. MQ and MDQ silicone resins were prepared by using dimethylphenylethoxysilane and tetramethyldivinyldisilazane as end-capping agents and tetraethyl orthosilicate as the source of unit Q. The influence of processing conditions on the yield was investigated. The relationship between the refractive index or thermal stability of silicone resins and the feeding capacity of end-capping agents was investigated.In chapter 3, methylphenylvinylethoxysilane was synthesized by Wurtz-Fitting reaction and its preparation conditions were optimized through orthogonal test. High purity methylphenylvinylethoxysilane was obtained by vacuum distillation method and used as initial material for preparing MQ silicone resins. Factors affected the preparing processes were investigated in details. Silicone resins prepared with this novel silane were compared with those MQ or MDQ resins prepared in chapter 2. Fi-nally, the prepared silicone resins were used as the reinforcing fillers for silicone rub-ber and the influence of M/Q ratio and the content of vinyl group in silicones resins on the mechanical properties and thermal stabilities of silicone rubber were also in-vestigated. |
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