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HWAHAK KONGHAK,
Vol.36, No.5, 701-706, 1998
Vol.36, No.5, 701-706, 1998
에멀젼/추출법에 의한 실리카 중공구 제조시 입도 제어
Particle Size Control in the Preparation of Hollow Silica Microspheres by Emulsion/Extraction Method
에멀젼/추출법을 이용하여 실리카 중공미세구를 제조하였고 이때 공정변수들이 최종 생성되는 미세구의 입도분포, 표면상태 및hollowness에 미치는 영향을 조사하였다. 실리카 속을 2-ethyl-1-hexanol에 분산시켜 에멀젼을 생성시키고 n-butanol을 사용하여 액적내부의 물을 추출시켜 실리카 중공미세구를 제조하였다. 에멀젼 생성단계에서 교반속도가 증가할수록, 실리카 솔의 농도가 감소할수록 생성되는 최종미세구의 평균입도가 감소하였다. 또한 실리카 솔의 농도가 증가할수록 미세구의 hollowness가 감소하였는데 60wt%에 이르면 거의 solid 미세구가 생성되었다. 계면활성제로 Span80을 첨가하면 미세구의 입도가 감소하지만 과다하게 투입하면 오히려 입자들이 서로 엉기는 현상이 관찰되었다. 투입한 실리카 솔을 모두 에멀젼화하는데 적절한 실리카 솔과 유기용매의 부피비는 1:5인 것으로 판단된다. 이 외에 열처리온도와 탈수액 투입량에 따른 영향도 고려하였다.
Hollow silica microspheres were prepared by emulsion/extraction method, where the changes of particle size distribution and surface state of the final microspheres were examined considering the effects of a number of processing variables. First, silica sols were emulsified by 2-ethyl-1-hexanol and then the formed droplets were water extracted to form the gelled hollow microspheres. Average particle size of the final microspheres decreased with increasing stirring speed in emulsion formation step and decreasing colloid concentration. Higher colloid sol concentration gives smaller hollowness of the final microspheres. Solid microspheres formed at colloidal silica sol concentration over 60wt%. In addition, average particle size of the final microspheres decreased with increasing percentage of Span80, but aggregation of the final micro-spheres occurred in the excessive addition. Moderate volume ratio of silica sol to dispersing agent was 1:5, where silica sol were completely used to form liquid droplets. Also the effects of sintering temperature and the volume of dehydrating liquid were examined.
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