| abstract |
An object of the present invention is to provide an abrasive composition for a magnetic disk substrate, in addition to reducing the ripple of the substrate after polishing and reducing the halo without reducing the productivity. The abrasive composition for a magnetic disk substrate contains colloidal silica, a water-soluble polymer compound, and water. The water-soluble polymer compound is a copolymer of a monomer having a carboxylic acid group, a monomer having an amidine group, and a monomer having a sulfonic acid group as essential component monomers. The weight average molecular weight of the water-soluble polymer compound is 1,000 to 1,000,000. |