公开(公告)号：US4756903A

公开(公告)日：1988-07-12

申请号：US18817

申请日：1987-02-19

申请人： Shinpo Shozo ,  Fushino Tetsuo ,  Hachijo Akihiro ,  Ohtsu Shozo

发明人： Shinpo Shozo ,  Fushino Tetsuo ,  Hachijo Akihiro ,  Ohtsu Shozo

IPC分类号： C01B33/187 ,  A61K8/00 ,  A61K8/25 ,  A61Q11/00 ,  C01B33/12 ,  C01B33/193 ,  A61K7/16

CPC分类号： C01B33/193 ,  A61K8/25 ,  A61Q11/00 ,  C01P2002/02 ,  C01P2006/12 ,  C01P2006/60

摘要： Silica base material for dentifrice having excellent transparency, prolonged stability and desired abrasiveness, has a specific surface area of 270-500 m.sup.2 /g as measured by BET method and 5-60 m.sup.2 /g by CTAB method, gives virtually amorphous X-ray diffraction pattern after firing at 1100.degree. C., and has a refractive index of 1.455-1.470. This base material can be prepared by reacting an alkali metal silicate solution with hydrochloric acid or sulfuric acid in the presence of an electrolyte, controlling the ratio of the rate of addition of chloride ion or sulfate ion to be at least 3:2 between the acidification stage in which the pH at the completion of the reaction is brought to 3.5 or less, and the silica crystallization stage in which the pH of the reaction system if brought to 10.0, and carrying out the acidification stage within 30 minutes.