Kao Corporation

Yoshiaki Oshima

Toshiya Hagihara

Shigeo Fujii

Kenichi Suenaga

Kazuhiko Nishimoto

Koichi Naito

Hiroaki Kitayama

Haruhiko Doi

Koji Taira

Norihito Yamaguchi

A polishing composition for a magnetic disk substrate of the present invention includes water, silica particles, and at least one or more selected from an acid, a salt of the acid, and an oxidizing agent. The silica particles are observed with a transmission electron microscope to measure a maximum diameter and a projected area of each particle, and a value obtained by dividing the area of a circle whose diameter is the maximum diameter of a silica particle by the projected area of the silica particle and multiplying the result by 100, is in the range of 100 to 130.

Polishing composition for magnetic disk substrate

To provide a polishing composition capable of increasing polishing rate and reducing surface roughness, without causing surface defects on a surface of an object to be polished; and a polishing process for a substrate to be polished. [1] a polishing composition comprising water, an abrasive, an intermediate alumina, and a polycarboxylic acid having 4 or more carbon atoms with no OH groups or a salt thereof, wherein a content of the intermediate alumina is from 1 to 90 parts by weight, based on 100 parts by weight of the abrasive; and [2] a polishing process for a substrate to be polished, comprising polishing a substrate to be polished under conditions that a composition of a polishing liquid during polishing is the composition as defined in item [1] above.

Polishing fluid composition

A polishing composition for memory hard disk containing 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 in the range of particle sizes of from 40 to 100 nm satisfy the following formula (1): V&#x2267;0.5&#xd7;R+40 (1), wherein the particle size is determined by observation with a transmission electron microscope (TEM). The polishing composition of the present invention can be even more suitably used for the manufacture of a substrate for precision parts such as substrates for memory hard disks.

Polishing composition

A roll-off reducing agent comprising one or more compounds selected from the group consisting of carboxylic acids having 2 to 20 carbon atoms having either OH group or groups or SH group or groups, monocarboxylic acids having 1 to 20 carbon atoms, and dicarboxylic acids having 2 to 3 carbon atoms, and salts thereof; and a roll-off reducing agent composition comprising a roll off-reducing agent comprising one or more compounds selected from the group consisting of carboxylic acids having 2 to 20 carbon atoms having either OH group or groups or SH group or groups, monocarboxylic acids having 1 to 20 carbon atoms, and dicarboxylic acids having 2 to 3 carbon atoms, and salts thereof; an abrasive; and water.

Roll-off reducing agent

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.

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.

Method for manufacturing substrate

A polishing composition for a substrate for memory hard disk, comprising silica particles in an aqueous medium, wherein the silica particles satisfy a specified relationship between an average particle size of the silica particles on the number basis and a standard deviation on the number basis, wherein the average particle size is obtained by a determination by transmission electron microscope (TEM) observation, and wherein a particle size and a cumulative volume frequency in a range of particle sizes of from 60 to 120 nm satisfies a specified relationship; a method of reducing microwaviness of a substrate for memory hard disk, comprising the step of polishing the substrate for memory hard disk with the polishing composition; and a method for manufacturing a substrate for memory hard disk, comprising the step of polishing a Ni&#x2014;P plated substrate for memory hard disk with the polishing composition. The method can be suitably used for the manufacture of a substrate for precision parts, such as a substrate for memory hard disk.

A polishing composition comprising an abrasive, water and an organic acid or a salt thereof, wherein the composition has a specified viscosity of from 1.0 to 2.0 mPa&#xb7;s at a shearing rate of 1500 sand 25&#xb0; C.; a roll-off reducing agent comprising a Br&#xf6;nsted acid or a salt thereof, having an action of lowering viscosity so that the amount of viscosity lowered is 0.01 mPa&#xb7;s or more, wherein the amount of viscosity lowered is expressed by the following equation:(Amount of Viscosity Lowered)=(Viscosity of Standard Polishing Composition)&#x2212;(Viscosity of Roll-Off Reducing Agent-Containing Polishing Composition),wherein the standard polishing composition is prepared which comprises 20 parts by weight of an abrasive, said abrasive being high-purity alumina having AlOpurity of 98.0% by weight or more composed of &#x3b1;-type co-random crystal, 1 part by weight of citric acid, and 79 parts by weight of water; the roll-off reducing agent-containing polishing composition is prepared which comprises 20 parts by weight of an abrasive, said abrasive being high-purity alumina having AlOpurity of 98.0% by weight or more composed of &#x3b1;-type co-random crystal, 1 part by weight of citric acid, 78.9 parts by weight of water and 0.1 parts by weight of a roll-off reducing agent; and the viscosity is a viscosity at a shearing rate of 1500 sand 25&#xb0; C. The polishing composition can be favorably used in polishing the substrate for precision parts.

A polishing composition comprising an abrasive, an oxidizing agent, a polishing accelerator, and water, wherein the polishing accelerator comprises an organic phosphonic acid; a method for manufacturing a substrate, comprising polishing a substrate to be polished with the above polishing composition; a method for polishing a substrate comprising polishing a substrate to be polished with the above polishing composition; a process for reducing fine scratches of a substrate, comprising polishing a substrate to be polished with the above polishing composition; and a process for accelerating polishing of a magnetic disk substrate, comprising applying the above polishing composition to a magnetic disk substrate to be polished. The polishing composition is highly suitable for polishing a magnetic disk substrate requiring high surface quality to be used in memory hard disk drives.

A polishing composition comprising an abrasive having an average primary particle size of 200 nm or less, an oxidizing agent, an acid having a pK1 of 2 or less and/or a salt thereof, and water, wherein the acid value (Y) of the polishing composition is 20 mg KOH/g or less and 0.2 mg KOH/g or more; a process for reducing fine scratches of a substrate, comprising polishing a substrate to be polished with the above-mentioned polishing composition; and a method for manufacturing a substrate, comprising polishing a substrate to be polished with the above-mentioned polishing composition. The polishing composition can be suitably used for final polishing memory hard disk substrates and polishing semiconductor elements.

A polishing composition comprising a chelating compound or a salt thereof; a partially esterified product and/or partially etherified product of a polyhydric alcohol compound; and water; a polishing composition comprising water, an abrasive, an intermediate alumina, and a chelating compound or a salt thereof, wherein the content of the intermediate alumina is from 1 to 50 parts by weight, based on 100 parts by weight of the abrasive; and a polishing composition comprising water, an abrasive, an intermediate alumina, a chelating compound or a salt thereof, and a partially esterified product and/or partially etherified product of a polyhydric alcohol compound, wherein the content of the intermediate alumina is from 1 to 50 parts by weight, based on 100 parts by weight of the abrasive. By using the polishing composition, the polishing rate can be increased, and the surface roughness can be lowered, without causing defects such as scratches and pits on the surface of an object to be polished.

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Wakayama, Japan

Yoshiaki Oshima