公开(公告)号：US5221497A

公开(公告)日：1993-06-22

申请号：US746634

申请日：1991-08-19

申请人： Yoshitane Watanabe ,  Mikio Ando ,  Kenji Tanimoto ,  Tsutomu Kagamimiya ,  Makoto Kawashima

发明人： Yoshitane Watanabe ,  Mikio Ando ,  Kenji Tanimoto ,  Tsutomu Kagamimiya ,  Makoto Kawashima

IPC分类号： C01B33/145 ,  C01B33/148

CPC分类号： C01B33/148 ,  C01B33/145

摘要： A method for preparing a stable silica sol having an SiO.sub.2 concentration of 40% or less, the colloidal particles of said silica having a particle size of 40 to 500 nm, as measured by dynamic light-scattering and having an elongated shape having a thickness of 5 to 40 nm and an elongation of 5 to 30 times the thickness in only one plane, the method comprising the steps (a), (b) and (c): (a) mixing an aqueous solution of Ca or Mg salt with an aqueous solution of active silicic acid having an SiO.sub.2 concentration of 1 to 6% and a pH value of 2 to 5, or with an aqueous acidic silica sol having a particle size of 3 to 30 nm, an SiO.sub.2 concentration of 0.5 to 25% and a pH value of 1 to 5 in a weight ratio of 1500 to 10000 ppm of (CaO or MgO)/SiO.sub.2 ; (b) mixing an alkali metal hydroxide with the solution obtained by step (a) in a molar ratio of 20 to 300 as SiO.sub.2 /M.sub.2 O, wherein M represents an alkali metal atom; and (c) heating the mixture obtained by step (b) at 60.degree. to 300.degree. C. for 0.5 to 40 hours.

摘要翻译： 制备SiO 2浓度为40％以下的稳定的二氧化硅溶胶的方法，通过动态光散射测定的所述二氧化硅的粒径为40〜500nm的胶体粒子，其厚度为 （a），（b）和（c）的方法：（a）将Ca或Mg盐水溶液与 SiO 2浓度为1〜6％，pH值为2〜5的活性硅酸水溶液，或粒径为3〜30nm，SiO 2浓度为0.5〜25％的酸性硅酸水溶液，以及 （CaO或MgO）/ SiO 2的重量比为1500〜10000ppm的pH值为1〜5; （b）将碱金属氢氧化物与作为SiO 2 / M 2 O的摩尔比为20〜300的步骤（a）得到的溶液混合，其中M表示碱金属原子; 和（c）将步骤（b）获得的混合物在60℃至300℃下加热0.5至40小时。