| 摘要 |
PURPOSE:To produce spherical silica having smooth surface and low impurity content, by hydrolyzing a specific silicon compound under specific condition, and calcining the product. CONSTITUTION:A silicon compound of formula (X is halogen; n is 0-4) refined by distillation, ion-exchange, etc. and containing <=0.05ppb each of U and Th is introduced together with steam through a double nozzle into a synthesis furnace, and is hydrolyzed at 300-600 deg.C and a retention time of 0.1-10sec. The molar ratio of HPV2PVO/silicon compound is 1.5-5. The hydrolysis product is calcined at 500-1,300 deg.C to remove the attached water and Cl and obtain a spherical silica having an average particle diameter of 1-5mum.
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