Polishing composition and polishing method

Abstract

A polishing composition of the present invention contains silicon dioxide, an acid, and water. Silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The acid is, for example, hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, boric acid, acetic acid, itaconic acid, succinic acid, tartaric acid, citric acid, maleic acid, glycolic acid, malonic acid, methanesulfonic acid, formic acid, malic acid, gluconic acid, alanine, glycin, lactic acid, hydroxyethylidene diphosphonic acid, nitrilotris(methylene phosphonic acid), or phosphonobutane tricarboxylic acid. The pH of the polishing composition is preferably in the range of 0.5 to 6. 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 acid, 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 acid is hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, or boric acid.  
     
     
         11 . The polishing composition according to  claim 1 , wherein the acid is acetic acid, itaconic acid, succinic acid, tartaric acid, citric acid, maleic acid, glycolic acid, malonic acid, methanesulfonic acid, formic acid, malic acid, gluconic acid, alanine, glycin, lactic acid, hydroxyethylidene diphosphonic acid, nitrilotris(methylene phosphonic acid), or phosphonobutane tricarboxylic acid.  
     
     
         12 . The polishing composition according to  claim 1 , wherein the content of the acid in the polishing composition is 0.05 to 10 mass %.  
     
     
         13 . The polishing composition according to  claim 12 , wherein the content of the acid in the polishing composition is 0.3 to 5 mass %.  
     
     
         14 . The polishing composition according to  claim 1 , wherein the pH of the polishing composition is 0.5 to 6.  
     
     
         15 . The polishing composition according to  claim 14 , wherein the pH of the polishing composition is 1 to 2.5.  
     
     
         16 . The polishing composition according to  claim 1 , further comprising a chelating agent, a surfactant, or a preservative.  
     
     
         17 . A method for polishing a glass substrate, the method comprising: 
 preparing a polishing composition comprising silicon dioxide, an acid, and water; and    polishing the surface of a glass substrate, using the prepared polishing composition.    
     
     
         18 . The method for polishing a glass substrate according to  claim 17 , 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.    
     
     
         19 . The method for polishing a glass substrate according to  claim 17 , wherein said preparing a polishing composition comprises diluting the polishing composition with water.  
     
     
         20 . The method for polishing a glass substrate according to  claim 19 , wherein the volume of water to be used for dilution of the polishing composition is not more than 50 times as large as the volume of the polishing composition before dilution.