Polishing composition and polishing method

Abstract

A polishing composition contains silicon dioxide, an alkaline compound, and water. Silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The alkaline compound is, for example, ammonium carbonate, potassium carbonate, sodium carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, ammonium phosphate, potassium phosphate, sodium phosphate, ammonium hydrogen phosphate, potassium hydrogen phosphate, or sodium hydrogen phosphate. The polishing composition can be suitably used in applications for polishing a glass substrate.

1 . A polishing composition for use in an application for polishing a glass substrate, the polishing composition comprising silicon dioxide, an alkaline compound, and water.  
     
     
         2 . The polishing composition according to  claim 1 , wherein the silicon dioxide is colloidal silica, fumed silica, or precipitated silica.  
     
     
         3 . The polishing composition according to  claim 2 , wherein the silicon dioxide is colloidal silica.  
     
     
         4 . The polishing composition according to  claim 3 , wherein the colloidal silica has a mean particle diameter D SA , which is determined from the specific surface area of the colloidal silica by a BET method, of 5 to 300 nm.  
     
     
         5 . The polishing composition according to  claim 3 , wherein the colloidal silica has a mean particle diameter D N4 , which is determined by a laser diffraction scattering method, of 5 to 300 nm.  
     
     
         6 . The polishing composition according to  claim 2 , wherein the silicon dioxide is fumed silica having a mean particle diameter D SA , which is determined from the specific surface area of the colloidal silica by a BET method, of 10 to 300 nm.  
     
     
         7 . The polishing composition according to  claim 2 , wherein the silicon dioxide is fumed silica having a mean particle diameter D N4 , which is determined by a laser diffraction scattering method, of 30 to 500 nm.  
     
     
         8 . The polishing composition according to  claim 1 , wherein the content of silicon dioxide in the polishing composition is 0.1 to 50 mass %.  
     
     
         9 . The polishing composition according to  claim 8 , wherein the content of silicon dioxide in the polishing composition is 3 to 30 mass %.  
     
     
         10 . The polishing composition according to  claim 1 , wherein the alkaline compound is ammonium carbonate, potassium carbonate, sodium carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, ammonium phosphate, potassium phosphate, sodium phosphate, ammonium hydrogen phosphate, potassium hydrogen phosphate, sodium hydrogen phosphate, potassium pyrophosphate, sodium pyrophosphate, potassium citrate, potassium hydrogen citrate, potassium gluconate, potassium succinate, ammonium acetate, potassium oxalate, ammonium hydrogen oxalate, ammonium tartrate, potassium tartrate, ammonium hydrogen tartrate, potassium sodium tartrate, potassium sorbate, calcium nitrate, potassium ferricyanide, ammonium fluoride, potassium fluoride, calcium fluoride, potassium hydroxide, ammonium hydroxide, or tetramethyl ammonium hydroxide.  
     
     
         11 . The polishing composition according to  claim 1 , wherein the content of the alkaline compound in the polishing composition is 0.05 to 10 mass %.  
     
     
         12 . The polishing composition according to  claim 11 , wherein the content of the alkaline compound in the polishing composition is 0.3 to 5 mass %.  
     
     
         13 . The polishing composition according to  claim 1 , further comprising an oxidizing agent.  
     
     
         14 . The polishing composition according to  claim 13 , wherein the oxidizing agent is hydrogen peroxide, ammonium persulfate, potassium chlorate, potassium perchlorate, sodium perchlorate, potassium periodate, sodium periodate, potassium bromate, or sodium bromate  
     
     
         15 . The polishing composition according to  claim 13 , wherein the content of the oxidizing agent in the polishing composition is 0.005 to 10 mass %.  
     
     
         16 . The polishing composition according to  claim 15 , wherein the content of the oxidizing agent in the polishing composition is 0.03 to 5 mass %.  
     
     
         17 . The polishing composition according to  claim 1 , further comprising a chelating agent, a surfactant, or a preservative.  
     
     
         18 . A method for polishing a glass substrate, the method comprising: 
 preparing a polishing composition comprising silicon dioxide, an alkaline compound, and water; and    polishing the surface of a glass substrate, using the prepared polishing composition.    
     
     
         19 . The method for polishing a glass substrate according to  claim 18 , wherein said polishing the surface of a glass substrate comprises: 
 preliminarily polishing the surface of the glass substrate; and    finish-polishing the surface of the preliminarily polished glass substrate, in which the polishing composition is used in the finish-polishing of the surface of the preliminarily polished glass substrate.    
     
     
         20 . The method for polishing a glass substrate according to  claim 18 , wherein said preparing a polishing composition comprises diluting the polishing composition with water.