Hoya Corporation

Konica Minolta, Inc.

Konica Minolta Advanced Layers, Inc.

Hazuki Nakae

Toshiharu Mori

Provided is an abrasive agent for substrates that includes, as an abrasive material component in the abrasive agent, cerium oxide as the main component. The abrasive agent for substrates includes soluble silica and cerium oxide. The concentration ratio of the soluble silica, calculated as Si content, and the cerium oxide in the abrasive agent is 0.001:1 to 0.1:1.

Abrasive agent for substrates and substrate manufacturing method

Provided is a method for manufacturing an abrasive agent including a dispersant and also including cerium oxide as a main abrasive material component. The method involves: a step for recovering an abrasive agent component by salting out a spent abrasive material slurry by using a cation of an element of the first Group or second Group with an ionic radius of 80 pm to 160 pm in six-coordinate conversion, and solid-liquid separating the cerium oxide by coagulation and sedimentation; and a step for adding a dispersant including an anionic polymer to the abrasive agent component after the recovery.

Abrasive agent manufacturing method

For the purpose of providing a glass substrate for an information recording medium capable of acquiring a low GA value, provided is the glass substrate for an information recording medium, wherein a surface of the glass substrate has an arithmetic mean undulation Wa of less than 0.6 nm, and a fine undulation having a root-mean-square height Rq of less than 0.01 nm at a measurement wavelength of 80-120&#x3bc;m in a radial direction.

Glass substrate for information recording medium, information recording medium and method of manufacturing glass substrate for information recording medium

Disclosed is a method of producing a glass substrate for an information recording medium including a precision polishing step of using a polishing material containing colloidal silica and performing precision polishing, under acidic conditions, on a glass material in which the amount of iron adhered on the surface is 0.5 ng/cmor less and the surface roughness Ra is 1 nm or less. Additionally disclosed is a glass substrate for an information recording medium produced by the foregoing method of producing a glass substrate for an information recording medium.

Method of producing glass substrate for information recording medium

Disclosed is a method of producing a glass substrate for an information recording medium including a rough polishing step of performing a rough polishing on a glass material containing 0.01 to 2 mass % of cerium oxide; a washing step of washing the glass material after the rough polishing step, so that the cerium content of the glass material surface becomes 0.125 ng/cmor less; and a precision polishing step of performing precision polishing on the glass material after the washing step by cyclically using a polishing material containing colloidal silica.

Method for producing glass substrate for information recording medium

For an information storage medium a glass substrate is produced in a method including the steps of: polishing a glass substrate with a polishing agent applied thereon; and subsequently, chemically strengthening a major surface of the glass substrate. The polishing agent contains cerium oxide at a purity equal to or larger than 99% by mass for CeO/TREO, and has an alkaline earth metal content having a total mass equal to or smaller than 10 ppm by mass. The step of polishing is performed with a soft polishing pad to polish the glass substrate.

Method for producing glass substrate for information storage medium, and information storage medium

According to the process for producing a glass substrate for an information-recording medium of the present invention, a glass plateis roughly polished by a polishing machineusing a polishing liquidcontaining a polishing agent containing cerium oxide as a main component in the rough polishing step, followed by cleaning so as to adjust the amount of cerium oxide on the surface of the glass plate to be 0.125 ng/cm2 or less. The glass plate after rough polishing is thereafter finely polished with a polishing agent containing colloidal silica in the fine polishing step.

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Kyoto, Japan

Hazuki Nakae