Patent ID: 6719819
Filing Date: 2004-04-13
Classification: B24B,C09G,C09K,G11B

Abstract:
A polishing composition containing a silica sol for an aluminum disk, comprising:a colloidal silica particle group having a monomodal numerical particle size distribution with primary particle sizes of 80 to 120 nm as observed on a transmission electron microscope being 90% or more of the total particle number, and having a mean particle size Da (particle size measured with the nitrogen adsorption method) in the range of 65 to 100 nm (referred to as colloidal silica particle group (a) hereinafter), a colloidal silica particle group having a monomodal numerical particle size distribution with primary particle sizes of 20 to 40 nm as observed on a transmission electron microscope being 90% or more of the total particle number, and having a mean particle size Dc (particle size measured with the nitrogen adsorption method) in the range of 15 to 25 nm (referred to as colloidal silica particle group (c) hereinafter), and a colloidal silica particle group having a monomodal numerical particle size distribution with primary particle sizes of 5 to 15 nm as observed on a transmission electron microscope being 90% or more of the total particle number, and having a mean particle size Dd (particle size measured with the nitrogen adsorption method) in the range of 8 to 12 nm (referred to as colloidal silica particle group (d) hereinafter), wherein said composition has a SiO2 concentration of 0.5 to 50% by weight, a water dispersed stable silica sol with the weight ratio of said colloidal silica particle group (a), said colloidal silica particle group (c) and said colloidal silica particle group (d) of W(a):W(c):W(d)=1:0.05 to 9.0:0.01 to 1.4, and the ratio Of Dc/Da of 0.15 to 0.38 and the ratio of Dd/Dc of 0.26 to 0.80.