Synthesis And Applications Of α-aminohydrocarbylsubstituted Ketoximosilane In RTV Silicone Rubber

Room temperature vulcanized (RTV) silicon rubber using ketoximosilanes as across linking agents occupies one of the market’s largest-selling of silicone rubber products. It has excellent properties such as good storage stability, free from peculiar smell and only slight corrosion on brass. Methyltris (methylethylketoxime) silane, vinyltris (methylethylketoxime) silane and phenyltris (methylethylketoxime) silane are the main three types of kexoximesilanes. Also additional catalyst is required because of the low curing speed, and dibutyl tin dilaurate and stannous octoate are the most commonly used. But organic tin compounds are toxic and may have some side effects on the preparation of RTV rubbers such as viscosity peak and hard glue packaging, etc.The a-aminohydrocarbyl-substituted ketoximosilanes are designed and prepared in order to solve the above problems, and their vulcanization properties without catalyst are also studied. Hydrolysis mechanisms of α-、β-and γ-three types of aminohydrocarbyl-substituted ketoximosilanes are discussed through theoretical calculation.This thesis mainly includes the following contents:1. Chloromethyltris (methylethylketoxime) silane was synthesized first through the reaction between chloromethyltrichlorosilane and methyl ethyl ketoxime, and then modificated by amines through amination reaction. The structrures of a-aminohydrocarbyl-substituted ketoximosilanes was identified by 1HNMR, 13CNMR and FT-IR, and the reaction conditions were optimized during the processes of synthesis.2. The a-aminohydrocarbyl-substituted ketoximosilanes and methyltri-(methylethylketoxime)silane were respectively mixed with α,ω-dihydroxypoly-dimethylsiloxane(PDMS) to research their cross linking abilities. Tack free time and viscosity variations were investigated to track the cross linking processes. Thermogravimetric analysis (TGA) of these mixures were carried out in nitrogen atmosphere. The results showed that mixures of a-aminohydrocarbyl-substitued ketoximosilanes and PDMS without catalyst vulcanized faster than that of methyltri (methylethylketoxime) using organic tin compounds as catalyst. Besides, thermal stabilities of the mixures using a-aminohydrocarbyl-substituted ketoximosilanes as cross linking agents were higher than that of methyltri (methylethylketoxime) and were barely affected by catalysts.3. Hydrolysis mechanisms of α-、β-and γ-three types of aminohydrocarbyl-substituted ketoximosilanes were investigated based on the density functional theories of quantum chemistry. The results showed that electronic effects of a-amino-substitutuent group had significant influence on Si atom. The bonds of Si-ON were activated and were more likely to leave. Therefore, the curing speed of a-aminohydrocarbyl-substituted ketoximosilanes was higher than that of γ-while β-aminohydrocarbyl-substituted ketoximosilanes were unsTable with the highest rate of all.