Patents by Inventor Ken Ishitobi
Ken Ishitobi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6607571Abstract: 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.Type: GrantFiled: August 21, 2002Date of Patent: August 19, 2003Assignees: Showa Denko K.K., Yamaguchi Seiken Kogyo K.K.Inventors: Ken Ishitobi, Masahiro Nozaki, Tadanori Nagao, Yoshiki Hayashi
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Publication number: 20030029095Abstract: 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.Type: ApplicationFiled: August 21, 2002Publication date: February 13, 2003Applicant: SHOWA DENKO K.K.Inventors: Ken Ishitobi, Masahiro Nozaki, Tadanori Nagao, Yoshiki Hayashi
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Patent number: 6488729Abstract: 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.Type: GrantFiled: September 29, 2000Date of Patent: December 3, 2002Assignees: Showa Denko K.K., Yamaguchi Seiken Kogyo K.K.Inventors: Ken Ishitobi, Masahiro Nozaki, Tadanori Nagao, Yoshiki Hayashi
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Publication number: 20020128327Abstract: A polishing composition includes at least water, alumina and a sol product derived from an aluminum salt. A magnetic recording disk substrate polished with the polishing composition suppresses formation of roll-off on the outer peripheral portion thereof, has a high-quality mirror-finished surface with few pits, nodules and scratches, and enables a distance between it and a magnetic head to be small, thereby making it possible to the recording density.Type: ApplicationFiled: January 11, 2002Publication date: September 12, 2002Applicant: SHOWA DENKO K.K.Inventors: Ken Ishitobi, Tetsuro Kumita, Kimihiro Hon, Yoshinori Suzuki
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Patent number: 6152976Abstract: 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.Type: GrantFiled: August 27, 1997Date of Patent: November 28, 2000Assignee: Showa Denko Kabushiki KaishaInventors: Ken Ishitobi, Norihiko Miyata
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Patent number: 5935278Abstract: 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.Type: GrantFiled: July 9, 1997Date of Patent: August 10, 1999Assignee: Showa Denko Kabushiki KaishaInventors: Ken Ishitobi, Takanori Kido, Hiromu Sakamoto
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Patent number: 5626640Abstract: 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.Type: GrantFiled: April 12, 1996Date of Patent: May 6, 1997Assignee: Showa Denko K.K.Inventor: Ken Ishitobi
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Patent number: 5609657Abstract: 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.Type: GrantFiled: February 22, 1996Date of Patent: March 11, 1997Assignee: Showa Denko K.K.Inventor: Ken Ishitobi
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Patent number: 4929257Abstract: 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.Type: GrantFiled: March 30, 1989Date of Patent: May 29, 1990Assignees: Showa Denko Kabushiki Kaisha, Yamaguchi Seiken Kogyo Kabushiki KaishaInventors: Kunihiro Miyazaki, Ken Ishitobi, Yosinobu Yamaguchi
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Patent number: 4915710Abstract: 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.Type: GrantFiled: March 16, 1989Date of Patent: April 10, 1990Assignees: Showa Denko Kabushiki Kaisha, Yamaguchi Seiken Kogyo Kabushiki KaishaInventors: Kunihiro Miyazaki, Ken Ishitobi, Yoshinobu Yamaguchi
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Patent number: 4883502Abstract: 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.Type: GrantFiled: October 11, 1988Date of Patent: November 28, 1989Assignee: Showa Denko Kabushiki KaishaInventors: Kunihiro Miyazaki, Ken Ishitobi