Kao Corporation

Kazuhiko Nishimoto

Toshiya Hagihara

Yoshiaki Oshima

Jiro Hashimoto

Haruhiko Doi

Kenichi Suenaga

Yosuke Uchino

Toshiaki Oi

A method for manufacturing an aluminosilicate glass substrate for a hard disk of the present invention includes polishing an aluminosilicate glass substrate to be polished with a polishing composition that includes silica particles, a polymer having a sulfonic acid group, and water, wherein an adsorption constant of the polymer having the sulfonic acid group on aluminosilicate glass is 1.5 to 5.0 L/g. The polymer having the sulfonic acid group is preferably a polymer having an aromatic ring. The weight average molecular weight of the polymer having the sulfonic acid group is 3000 to 100000.

Method for manufacturing an aluminosilicate glass substrate for hard disks

The present invention provides a polishing composition for a glass substrate having a pH of from 1 to 5 and containing silica particles having an average particle size of from 5 to 100 nm, wherein, in a projected image of the silica particles obtainable by an image analysis of electron photomicrographs, an average of an area ratio R of a projected area of the silica particles (A1) to an area of a maximum inscribed circle of the silica particles (A), i.e. (A1/A), is in the range of from 1.2 to 3.0, and the silica particles have an average of 2.0 to 10 projection portions having a curvature radius of from &#x2155; to &#xbd; of a radius of the maximum inscribed circle of the silica particles (r) on the outline of the silica particles in the projected image, and a method for manufacturing a glass substrate, including the step of polishing a substrate to be polished with a polishing load of from 3 to 12 kPa and at a pH of from 1 to 5 while allowing the polishing composition to be present between a polishing pad and the substrate to be polished. The polishing composition for a glass substrate of the present invention can be suitably used, for example, in the manufacture of glass hard disks, aluminosilicate glass for reinforced glass substrates, glass ceramic substrates (crystallized glass substrates), and the like.

Polishing composition for glass substrate

A polishing composition for a substrate for memory hard disk comprising water and silica particles, wherein the silica particles have a particle size distribution in which the relationship of a particle size (R) and a cumulative volume frequency (V) in a graph of particle size-cumulative volume frequency obtained by plotting a cumulative volume frequency (%) of the silica particles counted from a small particle size side against a particle size (nm) of the silica particles satisfies the above formula (1) and the above formula (2), and wherein a particle size at 90% of a cumulative volume frequency (D90) is within the range of 65 nm or more and less than 105 nm. By using the polishing composition of the present invention, there can be efficiently manufactured an Ni&#x2014;P plated substrate for a disk polished to have an excellent surface smoothness, in which the micropits are effectively reduced.

Polishing composition

A method for manufacturing a substrate, a polishing process for a substrate, a method of reducing microwaviness for a substrate, each including the step of polishing a substrate to be polished with a polishing composition containing an abrasive and water with a polishing pad of which surface member has an average pore size of from 1 to 35 &#x3bc;m; and a method of reducing scratches for a substrate, comprising the step of polishing a substrate to be polished with a polishing composition comprising an abrasive, an oxidizing agent, an acid, a salt thereof, or a mixture thereof and water, with a polishing pad of which surface member has an average pore size of from 1 to 35 &#x3bc;m. The method for manufacturing a substrate can be used for finish polishing of a memory hard disk or for polishing of a semiconductor element.

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Wakayama, Japan

Kazuhiko Nishimoto