Showa Denko Kabushiki Kaisha

Other

Showa Denko K.k.

Yamaguchi Seiken Kogyo Kabushiki Kaisha

Ken Ishitobi

Kunihiro Miyazaki

Masahiro Nozaki

Yoshiki Hayashi

Tadanori Nagao

Takanori Kido

Norihiko Miyata

Yoshinobu Yamaguchi

Yosinobu Yamaguchi

Hiromu Sakamoto

To provide a polishing composition which enables maintenance of excellent properties and high quality of the surface of a hard disk without lowering polishing rate during polishing of the surface, and which can provide a polished surface in which the amount of dub-off is considerably reduced as compared with that of a conventional level, a polishing composition containing water, a polishing material (particularly alumina), a polishing accelerator, and at least one of hydroxypropyl cellulose and hydroxyalkyl alkyl cellulose is provided.

Polishing composition and method

An abrasive composition for polishing a substrate for a magnetic recording disc is described, which comprises finely divided titanium oxide particles, an abrasion promoter, an optional water-soluble oxidizing agent, and water. This abrasive composition is used for polishing a substrate for a magnetic recording disc by a process wherein the substrate is polished with a pad while the abrasive composition is supplied between the substrate and the pad, and at least one of the pad and the substrate is rotated. The contents of the finely divided titanium oxide particles, the abrasion promoter and the optional water-soluble oxidizing agent are 2-20 wt. %, 1-20 wt. % and up to 10 wt. %, respectively, based on the weight of the abrasive composition as used for polishing the substrate.

Abrasive composition for disc substrate, and process for polishing disc

An abrasive composition for polishing a substrate for a magnetic recording disc is described, which comprises finely divided zirconium oxide particles, an abrasion promoter, an optional water-soluble oxidizing agent, and water. This abrasive composition is used for polishing a substrate for a magnetic recording disc by a process wherein the substrate is polished with a pad while the abrasive composition is supplied between the substrate and the pad, and at least one of the pad and the substrate is rotated. The contents of the finely divided zirconium oxide particles, the abrasion promoter and the optional water-soluble oxidizing agent are 2-20 wt. %, 1-20 wt. % and up to 10 wt. %, respectively, based on the weight of the abrasive composition as used for polishing the substrate.

Abrasive composition for magnetic recording disc substrate

A composition capable of forming uniform textured streaks and eliminating or reducing the occurrence of protrusions to as few as possible on the ground layer (the ground layer of a magnetic layer) of a magnetic disc. The composition comprises minute grains or powder of diamond etc., an alkylene gycol monoalkyl ether and a fatty acid or a metallic salt thereof.

Composition adapted for use in texturing process for magnetic disc

The composition for texturing a magnetic disk contains 0.1-5 weight %, based on the composition, of polycrystalline sintered alumina abrasives in a grinding fluid, the abrasives being produced by a sol-gel method comprising the steps of mixing a slurry of alumina hydrate with a dilute acid for solation, mixing the resultant alumina hydrate sol with a seed and/or a modifier, drying said alumina hydrate sol at 50.degree.-120.degree. C. for gelation, pulverizing and classifying the resultant gel, calcinating said gel at 400.degree.-900.degree. C., sintering the calcinated alumina particles at 1100.degree.-1400.degree. C., and pulverizing and classifying the resultant sintered alumina particles to a maximum particle size of 5 .mu.m or less and an average particle size of 0.1-3 .mu.m.

Composition for texturing magnetic disk

An abrasive composition comprising: an aluminous abrasive, preferably having an average particle size of 0.5-10 .mu.m and a concentration of 1 to 25% by weight; nickel sulfamate and/or sulfate, preferably having a concentration of 0.5 to 10% by weight; magnesium nitrate, preferably having a concentration of 0.1 to 12% by weight and water, the composition preferably having a pH of 4 to 7. This abrasive composition produces a superior effect, particularly a reduction of protrusions and pits and deep scratches when used for polishing an aluminum-based substrate for a magnetic recording disc.

Abrasive composition and process for polishing

An abrasive composition particularly suitable for polishing an aluminum-based substrate for a magnetic recording disc, the composition comprising: an alumineous abrasive, preferably in an amount of 3 to 25% by weight; a polishing accelerator of gluconic and/or lactic acid, preferably in an amount of 0.1 to 3% by weight; optionally with sodium gluconate and/or sodium lactate in an amount of 0.1 to 3% by weight; colloidal alumina, preferably in an amount of 0.1 to 5% by weight; and water, the composition typically having a pH of 3 to 5.

An abrasive composition comprising: an aluminous abrasive, preferably having an average particle size of 0.5-10 .mu.m and a concentration of 1 to 25% by weight; nickel sulfamate, preferably having a concentration of 0.5 to 10% by weight; and water, the composition preferably having a pH of 4 to 7. This abrasive composition produces a superior effect when used for polishing an aluminum-based substrate for a magnetic recording disc.

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Shiojiri, Japan

Ken Ishitobi