端羟基亚苯醚基二甲基硅氧烷预聚物及其室温硫化胶的制备

Preparation of Hydroxyl-Terminated Silphenylene-SildiphenyletherDimethyl-Siloxane Prepolymers and RTV Silicone Rubbers

以1,4-双(二甲基羟基硅基)苯(BHB)、4,4'-双(二甲基羟基硅基)二苯醚(BHBE)及低黏度羟基硅油(HO-PDMS)为主要原料,四甲基氢氧化铵硅醇盐为催化剂,通过平衡聚合法合成了端羟基亚苯基-亚苯醚基-二甲基硅氧烷预聚物(p-BHB-BHBE-DMS)。研究了投料比、反应温度、反应时间、催化剂用量对预聚物黏度的影响。结果表明,预聚物黏度与BHB、BHBE的加入量正相关,且BHBE使预聚物黏度增加的幅度比BHB使预聚物黏度增长的幅度大,BHB、BHBE和羟基硅油的较佳质量比为22/11/67;随着反应温度升高,预聚物的黏度逐渐降低,较佳反应温度为110～120℃;随反应时间延长,体系黏度先明显增加,随后变缓,合适的反应时间为4～5 h;随催化剂用量的增加,预聚物的黏度呈非线性降低,通过调整催化剂的用量可控制预聚物的黏度。在较佳条件下,通过改变BHB和BHBE的质量比,合成了黏度(25℃)在6 000～30 000 mPa.s的预聚物,其收率为82%～85%。以此预聚物为基胶配成脱醇型双组分室温硫化亚苯醚基硅橡胶,其硫化胶经过250℃×24 h热老化后,拉伸强度小幅提高;随着BHBE用量的增加,硫化胶的拉伸强度和伸长率均提高。

The hydroxyl-terminated silphenylene-sildiphenylether-dimethyl-siloxane prepolymers(p-BHB-BHBE-DMS) were synthesized by equilibrium polymerization of silanol-terminated dimethylsiloxane oligomers(HO-PDMS) with 1,4-bis(dimethylhydroxysilyl)benzene(BHB) and 4,4'-bis(dimethylhydroxysilyl)diphenyl ether(BHBE) with the silanol salt of tetramethyl ammonium hydroxide as the catalyst.The effects of the formulation,reaction temperature and time,and usage of the catalyst on the viscosity of the prepolymers were investigated.The results were as follows: firstly,the viscosity of the prepolymers showed a positive correlation with both the existence of BHB and BHBE,and the contribution of BHBE to the increase of viscosity was greater than that of BHB,while the preferable mass ratios of BHB,BHBE and(HO-PDMS) were 22%,11% and 67% respectively;secondly,with increasing the reaction temperature,the viscosity of the prepolymers was decreased and the best reaction temperature was in the range of 110~120℃;moreover,with increasing the reaction time,the viscosity of the prepolymers was first increased obviously and then tended to be stable and the most suitable time was 4~5 hours;lastly,the viscosity of the prepolymers was decreased nonlinearly with increasing the catalyst and its viscosity,which could be controlled by adjusting content of the catalyst.The viscosities(25℃) of the prepolymers synthesized under the best process conditions ranged between 6,000 mPa · s to 30,000 mPa · s and the yield of these prepolymers ranged between 82% to 85%.The two-component dealcoholization type room-temperature-vulcanizing(RTV) sildiphenylether-based silicone rubbers were prepared from the above prepolymers.The tensile strength of all the RTV silicone rubbers showed small increase after thermal aging under 250 ℃ for 24 hours.With the increase of BHBE,the tensile strength and breaking elongation increased simultaneously.