甲基苯基环硅氧烷的制备工艺研究

Study on the Preparation Techniques of Methylphenylcyclosiloxanes

甲基苯基环硅氧烷是指硅原子上同时含有甲基和苯基的环型硅氧烷,结构通式可简单表示为(MePhSiO)_n (n≥3),是制备高性能聚甲基苯基硅氧烷材料的重要原料.具有广阔的应用前景。在以往的研究报道中,甲基苯基环硅氧烷的制备均采用高纯的甲基苯基二氯硅烷(质量百分数大于99.5%)为原料,通过直接水解或在溶剂中水解,得到聚甲基苯基硅氧烷,然后采用碱催化热裂解而得。研究内容多以专利形式报道,对制备过程中的影响因素研究不够详尽。在我国,制备甲基苯基环硅氧烷所需的原料甲基苯基二氯硅烷是通过热缩合法生产的,主要的副产物为苯基三氯硅烷。由于两者沸点相近(分别为205.0℃和201.0℃),难以分离。而苯基三氯硅烷的存在,使得热缩合法生产的甲基苯基二氯硅烷难以直接应用于线型聚甲基苯基硅氧烷材料的生产,极大地限制了其应用领域。杭州师范大学以热缩合法生产的含苯基三氯硅烷的甲基苯基二氯硅烷为原料,不用溶剂,采用直接水解缩聚,以LiOH催化热裂解,制备了甲基苯基环硅氧烷,并可用做生产线型聚甲基苯基硅氧烷产品的原料,从而扩展了热缩法生产甲基苯基二氯硅烷的应用范围。与原有的制备方法相比,具有原料易得、工艺简单、生产成本低等优点。

The polymethylphenylcyclosiloxanes were prepared by cohydrolysis-condensation, catalytic alkaline splitting process etc.based on methylphenyldichlorosilane containing phenyltrichlorosilane from thermal condensation process as raw materials.The factors influencing on the preparation techniques of methylphenylcyclosiloxanes such as the components of feedstock,hydrolysis temperature,molar ratio of H_2O to Si-Cl bonds and dosage of catalyst were investigated,and the optimized technique parameters for cohydrolysis were obtained.The optimum hydrolysis conditions were as follows:the reaction temperature was 50～70℃,reaction time was 2～4h,the molar ratio of H_2O to Si-Cl bonds was 7～10.And the optimum alkaline splitting conditions were obtained in the presence of LiOH as catalyst with its mass fraction in the range of 1.5%.The yield of methylphenylcyclosiloxanes was 97.0% and the purity was 99.5% maximally.The obtained methylphenylcyclosiloxanes were characterized by NMR and GC-MS.