Method of manufacturing abrasive composition

Abstract

A process for producing a polishing composition excelling in dispersion stability wherein the amount of agglomerated particles is reduced. In step 1 - 1 thereof, ultrapure water is adjusted so as to have a pH value of 1.0 to 2.7. Under shearing force given by a high shear disperser, fumed silica powder of 50 to 200 m 2 /g specific surface area is charged therein until an initial silica concentration of 46 to 54 wt %, and the high shear disperser is operated so as to apply shearing force for 1 to 5 hours. In step 1 - 2 , a small amount of ultrapure water is added to the silica dispersion so as to realize a silica concentration of 45 to 53 wt % and shearing force is applied for 10 to 40 minutes. In step 1 - 3 , ultrapure water is added to the silica dispersion so as to realize a silica concentration of 33 to 44 wt % and shearing force is applied for 0.5 to 4 hours. In step 2 - 1 , the silica dispersion is added to an aqueous basic substance solution prepared so that a pH value after mixing is in a range of 8 to 12 and so that silica concentration is in a range of 10 to 30 wt %.

1 . A method of manufacturing an abrasive composition comprising: 
 a first step of preparing an acid fumed silica dispersion; and    a second step of adding the fumed silica dispersion to an aqueous basic substance solution which is prepared so that the abrasive composition to be obtained after the end of mixing with the fumed silica dispersion has predetermined pH and silica concentration, and mixing the fumed silica dispersion and the aqueous solution.    
   
   
       2 . The method of  claim 1 , wherein the first step includes the step of: 
 feeding fumed silica into water which has been prepared to have a pH of 1.0 to 2.7 so that an initial silica concentration reaches 46 to 54 wt % and applying a high shearing force, thereby preparing a fumed silica dispersion;    adding water to the fumed silica dispersion so that its silica concentration reaches 45 to 53 wt %; and    further adding water to the fumed silica dispersion so that its silica concentration reaches 33 to 44 wt %.    
   
   
       3 . The method of  claim 1 , wherein the aqueous basic substance solution is prepared so that the abrasive composition has a pH of 8 to 12 and a silica concentration of 10 to 30 wt %.  
   
   
       4 . The method of  claim 1 , wherein the mixing of the fumed silica dispersion and the aqueous basic substance solution is finished in less than 5 hours in the second step.  
   
   
       5 . The method of  claim 1 , wherein the fumed silica has a relative surface area of 50 to 200 m 2 /g.  
   
   
       6 . The method of  claim 1 , wherein the aqueous basic substance solution contains at least any of ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide or magnesium hydroxide.  
   
   
       7 . The method of  claim 1 , further comprising a third step of filtering the abrasive composition obtained in the second step with a filter having a filtering accuracy of 1 to 4 μm.  
   
   
       8 . The method of  claim 2 , wherein the aqueous basic substance solution is prepared so that the abrasive composition has a pH of 8 to 12 and a silica concentration of 10 to 30 wt %.  
   
   
       9 . The method of  claim 2 , wherein the mixing of the fumed silica dispersion and the aqueous basic substance solution is finished in less than 5 hours in the second step.  
   
   
       10 . The method of  claim 3 , wherein the mixing of the fumed silica dispersion and the aqueous basic substance solution is finished in less than 5 hours in the second step.  
   
   
       11 . The method of  claim 8 , wherein the mixing of the fumed silica dispersion and the aqueous basic substance solution is finished in less than 5 hours in the second step.  
   
   
       12 . The method of  claim 2 , wherein the fumed silica has a relative surface area of 50 to 200 m 2 /g.  
   
   
       13 . The method of  claim 3 , wherein the fumed silica has a relative surface area of 50 to 200 m 2 /g.  
   
   
       14 . The method of  claim 4 , wherein the fumed silica has a relative surface area of 50 to 200 m 2 /g.  
   
   
       15 . The method of  claim 2 , wherein the aqueous basic substance solution contains at least any of ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide or magnesium hydroxide.  
   
   
       16 . The method of  claim 3 , wherein the aqueous basic substance solution contains at least any of ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide or magnesium hydroxide.  
   
   
       17 . The method of  claim 4 , wherein the aqueous basic substance solution contains at least any of ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide or magnesium hydroxide.  
   
   
       18 . The method of  claim 2 , further comprising a third step of filtering the abrasive composition obtained in the second step with a filter having a filtering accuracy of 1 to 4 μm.  
   
   
       19 . The method of  claim 3 , further comprising a third step of filtering the abrasive composition obtained in the second step with a filter having a filtering accuracy of 1 to 4 μm.  
   
   
       20 . The method of  claim 4 , further comprising a third step of filtering the abrasive composition obtained in the second step with a filter having a filtering accuracy of 1 to 4 μm.