高导热阻燃有机硅灌封胶的制备

以乙烯基硅油、含氢硅油为基础胶料,十六烷基三甲氧基硅烷改性氧化铝为导热填料,二乙基次膦酸铝(ADP)为阻燃剂,制得导热阻燃绝缘有机硅电子灌封胶。研究了改性氧化铝用量对灌封胶黏度、导热性、阻燃性的影响,观察了燃烧残余物的形貌。结果表明,这种改性氧化铝有低吸油值,填充量对灌封胶黏度影响小,所制备的灌封胶具有良好导热性能;而ADP不仅展现出对灌封胶良好的阻燃性,而且还能与改性氧化铝产生协效阻燃性和抑烟作用,同时灌封胶也具有良好的流动性、力学性能和电绝缘性能。当ADP用量50份、改性氧化铝用量600份时,灌封胶的黏度为8 500 mPa·s,硫化后胶条的热导率达2.12 W/m·K,垂直燃烧达到FV-0级,拉伸强度1.72 MPa,拉断伸长率62%,体积电阻率3.9×1012Ω·cm。

Preparation of Silicone Encapsulant with High Thermal Conductivity and Flame Retardancy

The silicone encapsulant with properties of thermal conductivity , flame retardancy and insula-tion, was prepared by vinyl silicone fluid and polymethyl hydrogen siloxane fluid as the basic materials , hexa-decyltrimethoxysilane modified alumina as the thermally conductive filler , and aluminum diethyl phosphinate （ ADP） as the flame retardant .The content of the modified alumina affected the viscosity of the sealant , and offered high thermal conductivity and flame retardancy .The morphology of the combustion residues was ob-served.Results show that the modified alumina has low oil absorption value , whose filling quantity has little effect on the viscosity of the sealant , thus, the prepared sealant owns good thermal conductivity .ADP not only displays good flame retardancy for the silicone encapsulant , but also provides flame retardant synergy and smoke suppression along with the modified alumina .With loadings of ADP 50 phr, modified alumina 600 phr, the viscosity of the generated sealant is 8500 mPa· s and the cured sealant shows a thermal conductivity of 2.12 W/m· K, a limiting oxygen index of 46% with the vertical flame test rating FV-0, a tensile strength of 1.72 MPa, an elongation at break of 62%, and a volume resistivity 3.9 ×1012 Ω· cm.