Polishing composition

Abstract

A polishing composition comprising an abrasive and water, wherein the polishing composition has an index of degree of sedimentation of 80 or more and 100 or less; a process for producing a substrate comprising polishing a substrate to be polished using the above-mentioned composition; a process for preventing clogging of a polishing pad comprising applying the above-mentioned composition; a process for preventing clogging of a polishing pad comprising applying the above-mentioned composition to polishing with a polishing pad for a nickel-containing object to be polished; and a process for preventing clogging of a polishing pad comprising applying a composition comprising a hydrophilic polymer having two or more hydrophilic groups in its molecule and a molecular weight of 300 or more, or a compound capable of dissolving nickel hydroxide at a pH of 8.0, and water to polishing with a polishing pad for a nickel-containing object to be polished.

What is claimed is:  
     
         1 . A polishing composition comprising an abrasive and water, wherein the polishing composition has an index of degree of sedimentation of 80 or more and 100 or less.  
     
     
         2 . The polishing composition according to  claim 1 , further comprising a hydrophilic polymer compound or a compound capable of dissolving nickel hydroxide at a pH of 8.0.  
     
     
         3 . The polishing composition according to  claim 2 , wherein the hydrophilic polymer compound is a hydrophilic polymer having two or more hydrophilic groups in its molecule and a molecular weight of 300 or more.  
     
     
         4 . The polishing composition according to  claim 3 , wherein the hydrophilic group is an anionic group.  
     
     
         5 . The polishing composition according to any one of  claims 2  to  4 , wherein the compound capable of dissolving nickel hydroxide at a pH of 8.0 is glycine, ascorbic acid or citric acid.  
     
     
         6 . The polishing composition according to any one of  claims 1  to  5 , further comprising: 
 compound group (A): one or more compounds selected from the group consisting of carboxylic acids having 2 to 20 carbon atoms and having either OH group or groups or SH group or groups, monocarboxylic acids having 1 to 20 carbon atoms, dicarboxylic acids having 2 to 3 carbon atoms, and salts thereof; and/or  
 compound group (B): one or more compounds selected from the group consisting of polycarboxylic acids having 4 or more carbon atoms and having neither OH group or groups nor SH group or groups, aminocarboxylic acids, amino acids, and salts thereof.  
 
     
     
         7 . The polishing composition according to any one of  claims 1  to  6 , wherein the abrasive has a primary average particle size of 1 μm or less.  
     
     
         8 . The polishing composition according to any one of  claims 1  to  7 , which is used for polishing a magnetic disk substrate.  
     
     
         9 . A process for producing a substrate comprising polishing a substrate to be polished using the composition of any one of  claims 1  to  8 .  
     
     
         10 . A process for preventing clogging of a polishing pad comprising applying the composition of any one of  claims 1  to  8 .  
     
     
         11 . A process for preventing clogging of a polishing pad comprising applying the composition of any one of  claims 1  to  8 , to polishing with a polishing pad for a nickel-containing object to be polished.  
     
     
         12 . A process for preventing clogging of a polishing pad comprising applying a composition comprising: 
 a hydrophilic polymer having two or more hydrophilic groups in its molecule and a molecular weight of 300 or more, or a compound capable of dissolving nickel hydroxide at a pH of 8.0, and    water,    to polishing with a polishing pad for a nickel-containing object to be polished.    
     
     
         13 . The process according to  claim 12 , wherein the compound capable of dissolving nickel hydroxide at a pH of 8.0 is one or more compounds selected from the group consisting of carboxylic acids having 2 to 20 carbon atoms and having either OH group or groups or SH group or groups, monocarboxylic acids having 1 to 20 carbon atoms, dicarboxylic acids having 2 to 3 carbon atoms, α-amino acids having 2 to 3 carbon atoms, enolic organic acids having 3 to 10 carbon atoms, and salts thereof, wherein the content of the compound is 0.01% by weight or more and less than 2% by weight.