烷氧基封端聚硅氧烷及其脱醇型RTV-1硅橡胶的研制

Preparation of Polyalkoxysilyl-terminated Polysiloxane and Dealcoholized RTV-1 Silicone Rubber

通过α,ω-二羟基聚二甲基硅氧烷(107硅橡胶)与烷氧基硅烷的"封端"反应,制得烷氧基封端聚硅氧烷;再配合纳米碳酸钙、交联剂和钛酸酯催化剂,制得脱醇型单组分室温硫化(RTV-1)硅橡胶。探讨了封端剂类型、纳米碳酸钙和交联剂用量、钛酸酯种类和用量对硅橡胶性能的影响。结果表明,以环己酮肟为催化剂、乙烯基三甲氧基硅烷为封端剂,对黏度20 000 mPa.s的107硅橡胶进行封端制成的烷氧基封端聚硅氧烷(PDMS-4)最适合作脱醇型RTV-1硅橡胶的基胶;当PDMS-4用量为100份、纳米碳酸钙用量为100～130份、交联剂用量为5份、螯合型钛酸酯用量为4.0～5.0份时,脱醇型硅橡胶在生产过程中无"黏度高峰"效应,硫化速度适中,触变性较好,储存期长达1年;邵尔A硬度大于35度,拉伸强度大于2.0 MPa,拉断伸长率大于400%;无需添加增粘剂,对玻璃、铝合金、PC、ABS等材料具有良好的粘接性。

A polyalkoxysilyl-terminated polydimethylsiloxane was prepared by the end-capping reaction of α, ω-dihydroxy dimethylpolysiloxane （107 gel） and multi-alkoxy silane. The obtained polyalkoxysilyl-termi- nated polydimethylsiloxane was formulated with nanometer calcium carbonate, cross-linker, and titanium com- pound to prepare one-component room temperature vulcanizable （RTV-1） silicone rubber. The effects of types of base polymer, amounts of nanometer CaCO3 and cross-linker, amounts and types of titanium catalyst on the properties of the rubber were investigated. It showed that polyalkoxysilyl-terminated dimethylpolysilox- ane （PDMS-4） prepared by 107 gel of 20 000 mPa.s viscosity （25 ℃ ） and Cyclohexanone oxime used as catalyst and vinyl trimethoxysilane as terminating agent was desired for the dealcoholized RTV-1 silicone rub- ber. The RTV-1 silicone rubber was preferably composed of 100 parts of PDMS-4, 100 × 130 parts of nanome- ter CaCO3, 5 parts of cross-linker and 4.0 - 5.0 parts of chelate titanium catalyst （ DIPEAT or DIBEAT）. The RTV-1 rubber showed no ＂viscosity peak＂ when mixing the titanium to PDMS-4, with appropriate tack- free time, good thixotropic property, and prolonged shelf life to 1 year, and excellent mechanical properties with hardness 〉 35 shore A, tensile strength 〉 2. 0 MPa and elongation 〉 400%. In addition, it shows exten- sive adhesion properties to glass, aluminum alloy, ABS, and PC, without use of silane coupling agent as the adhesion promoter.