橄榄石酸溶制备超细二氧化硅工艺简单、生产成本低。但是制备的超细二氧化硅表面羟基键合严重、分散性能差、易团聚。利用硅烷偶联剂对橄榄石酸溶制备的超细二氧化硅进行改性研究。采用单因素实验考察了硅烷偶联剂品种、改性时间、改性温度及改性剂用量等因素对超细二氧化硅改性效果的影响。实验结果表明,在硅烷偶联剂KH-550加入量为6 mL/g、改性时间为5 h、改性温度为75 ℃条件下,制备的超细二氧化硅表面的羟基数量减少至2.08×10 ²⁰ 个/g、接枝率为8.35%、接触角达到101.51°,极大地提高了超细二氧化硅的表面疏水性。

Preparation of ultrafine silica by olivine acid dissolution is simple and low-cost,however,the ultrafine silica are liable to agglomerate with poor dispersing property due to strong hydrophilicity.Silane coupling agent was used to modify the ultrafine silica prepared by olivine acid dissolution.The effects of varieties and dosage of modifier,modifying time and temperature on the modification of silica were investigated by single factor method.The results show that the number of hydroxyl on the surface of ultrafine silica can be reduced to 2.08×10 ²⁰ units/g,the grafting rate is 8.35% and the contact angle is 101.51° when the addition of silane coupling agent KH-550 is 6 mL/g,modifying time is 5 h and reaction temperature is 75 ℃,which improves the hydrophobicity of ultrafine silica greatly.