Patent ID: 6398827
Filing Date: 2002-06-04
Classification: C09G,C09K

Abstract:
A polishing composition for polishing alumina disks, comprising a stable aqueous silica sol containing moniliform colloidal silica particles having a ratio (D1/D2) of a particle diameter D1 nm (as measured by dynamic light scattering method) to a mean particle diameter D2(as measured by nitrogen adsorption method) of 3 or more, wherein D1 is between 50 to 800 nm and D2 is between 10 to 120 nm, said moniliform colloidal silica particles being composed of spherical colloidal silica particles and a metal oxide-containing silica bond which bonds these spherical colloidal silica particles together, wherein the spherical colloidal silica particles are linked together in rows in only one plane by observation through an electron microscope, and further wherein said polishing composition containing 0.5 to 50% by weight of said moniliform colloidal silica particles.