| 摘要 |
PURPOSE:Lightweight silica particles having porosity, improved mechanical strength, high water absorption rate and a large amount of water absorption, consisting of aggregate of specific fine particles. CONSTITUTION:1l organic medium (e.g. toluene) containing 100-50,000ppm surface active agent (e.g. sorbitan fatty acid ester) is blended with 0.1-0.6l aqueous solution containing 3-20wt% calculated as silica content of water-glass and stirred at 15-80 deg.C liquid temperature, solidification temperature of liquid medium + 5 deg.C - boiling point of liquid medium -25 deg.C at 4,000-12,000rpm for 10-100min. Then, the stirring rate is dropped to 800-2,500rpm, 5-25% dilute CO2 gas is introduced in a ratio of 0.05-0.40Nm<3>/hr to the solution for 5-40min. The solution temperature is kept at 15-30 deg.C and 100% CO2 gas is fed in a ratio of 0.01-0.80Nm<3>/hr to the solution for 5-40min to give silica particles which consist of spherical tertiary particles having 0.1-5,000mu average particle diameter wherein secondary particles having 200-1,000Angstrom average particle diameter are aggregated wherein approximately spherical primary particles having 100-200Angstrom average particles diameter are aggregated, have 50-200Angstrom distance between the primary particles and 200-1,000Angstrom distance between the secondary particles and constitute the whole porous material by these distances. |
