Patent ID: 7147682
Filing Date: 2006-12-12
Classification: C09G,C09K

Abstract:
1. A polishing composition for a substrate for memory hard disk comprising an abrasive in an aqueous medium, wherein the abrasive comprises silica particles having particle sizes of from 5 to 120 nm in an amount of 50% by volume or more, wherein the abrasive comprises: (i) 10 to 70% by volume of small size silica particles having particle sizes of 5 nm or more and less than 40 nm based on an entire amount of the silica particles having particle sizes of from 5 to 120 nm; (ii) 20 to 70% by volume of intermediate size silica particles having particle sizes of 40 nm or more and less than 80 nm based on an entire amount of the silica particles having particle sizes of from 5 to 120 nm; and (iii) 0.1 to 40% by volume of large size silica particles having particle sizes of 80 nm or more and 120 nm or less based on an entire amount of the silica particles having particle sizes of from 5 to 120 nm.