Minolta Company, Ltd.

Konica Minolta Opto, Inc.

Kaneka Corporation

Other

Hoya Corporation

Konica Minolta, Inc.

Hideki Kawai

Toshiharu Mori

Kazuhiko Ishimaru

Hideki Nagata

Hiroshi Yuki

Akira Sugimoto

Hiroaki Sawada

Kenichi Sasaki

Shinichi Saeki

Hiroshi Kajita

Masahiro Miyamoto

Mamoru Kadokura

Yukitoshi Nakatsuji

Akira Takaki

Akio Oogaki

Shinji Fukumoto

Shiro Nishimoto

Mitsugu Tokunaga

Hisashi Onuma

Disclosed is a method for producing a glass substrate, which involves a first polishing step and a second polishing step both for polishing the surface of the glass substrate with a polishing solution containing a polishing agent. The method is characterized by additionally involving a heating step for heating the glass substrate, wherein the heating step is carried out after the first polishing step and before the second polishing step.

Method for producing glass substrate and method for producing magnetic recording medium

Provided are a glass substrate for information recording media wherein air bubbles can be sufficiently removed, and an information recording medium using the glass substrate. The glass substrate contains 65 to 90 mass % of SiO+Al2O+BO(where SiOis 45 to 75 mass %, AlOis 1 to 20 mass %, and BOis 0 to 8 mass %), 7 to 20 mass % of R2O (where R represents Li, Na, or K), 0.1 to 12 mass % of R'O (where R&#x2032; represents Mg, Ca, Sr, Ba, or Zn), and 0.5 to 10 mass % of TiO+ZrO. Moreover, the glass substrate contains at least one multivalent element selected from among a group consisting of V, Mn, Ni, Mo, Sn, Ce, and Bi; the molar ratio of the total amount of the oxide of the multivalent element to the total amount of TiO+ZrOis within the range of 0.05 to 0.50.

Glass substrate for information recording media and information recording medium

The present invention relates to the glass substrate for an information recording medium comprising the following glass components: SiO: 52 to 67; AlO: 8 to 20; BO: 0 to 6, with these three oxides FMO: 70 to 85; LiO: 0.5 to 4; NaO: 1 to 8; KO: 0 to 5; and with these three oxides R2O: 5 to 15; MgO: 2 to 9; CaO: 0.1 to 5; BaO: 0 to 3; SrO: 0 to 3; ZnO: 0 to 5; and with these five oxides: 5 to 15; YO: 0 to 4; LaO: 0 to 4; GdO: 0 to 4; CeO: 0 to 4; TiO: 1 to 7; HfO: 0 to 2; ZrO: 0 to 5; NbO: 0.2 to 5; and TaO: 0 to 5, and satisfies LiO/R2O: 0.05 to 0.35; LiO/FMO: 0.005 to 0.035; LiO/(MgO+ZnO): less than 2 and NbO/SiO: 0.01 to 0.075.

Glass substrate for information recording medium

The present invention provides a method of easily chamfering and polishing an inner peripheral face and an outer peripheral face of a glass disk at low cost. By continuously supplying fresh etchants to an inner peripheral face and an outer peripheral face of a glass disk stacked body in which a plurality of glass disks are stacked, the inner and outer peripheral faces are polished.

Glass disk processing method

A glass substrate for information recording medium, said glass substrate being composed of an alminosilicate glass containing 60-75% by mass of SiO, 5-18% by mass of AlO, 3-10% by mass of LiO, 3-15% by mass of NaO and 0.5-8% by mass of ZrOrelative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one polyvalent element selected from the group consisting of V (vanadium), Mn (manganese), Ni (nickel), Nb (niobium), Mo (molybdenum), Sn (tin), Ce (cerium), Ta (tantalum) and Bi (bismuth). The molar ratio of the total amount of the polyvalent elements to the amount of ZrOis within the range of 0.05-0.50.

Glass substrate for information recording medium and information recording medium

A glass substrate for information recording medium, said glass substrate being composed of an aluminosilicate glass containing 60-75% by mass of SiO, 5-18% by mass of AlO, 3-10% by mass of LiO, 3-15% by mass of NaO and 0.5-8% by mass of ZrOrelative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one substance selected from the group consisting of SO(sulfurous acid), F (fluorine), Cl (chlorine), Br (bromine) and I (iodine), as a refining agent. The molar ratio of the total amount of the refining agent to the amount of ZrOis within the range of 0.05-0.50.

A glass substrate for information recording medium, said glass substrate being composed of an aluminosilicate glass containing 60-75% by mass of SiO, 5-18% by mass of AlO, 3-10% by mass of LiO, 3-15% by mass of NaO and 0.5-8% by mass of ZrOrelative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one substance selected from the group consisting of SO(sulfurous acid), F (fluorine), Cl (chlorine), Br (bromine) and I (iodine), as a refining agent. The molar ratio of the total amount of the refining agent to the amount of AlO3 is within the range of 0.02-0.20.

A glass substrate for information recording medium, said glass substrate being composed of an aluminosilicate glass containing 60-75% by mass of SiO, 5-18% by mass of AlO, 3-10% by mass of LiO, 3-15% by mass of NaO and 0.5-8% by mass of ZrOrelative to the entire glass components. The glass substrate for information recording medium contains neither As (arsenic) nor Sb (antimony), while containing at least one polyvalent element selected from the group consisting of V (vanadium), Mn (manganese), Ni (nickel), Nb (niobium), Mo (molybdenum), Sn (tin), Ce (cerium), Ta (tantalum) and Bi (bismuth). The molar ratio of the total amount of the polyvalent elements to the amount of AlOis within the range of 0.02-0.20.

Disclosed is a mold for glass substrate molding, which enables to produce a glass substrate having high flatness by a method for producing a glass substrate through press molding of molten glass. Also disclosed is a method for producing a glass substrate by using such a mold. Specifically disclosed is a mold comprising a lower mold having a first molding surface for pressing a molten glass supplied thereto, and an upper mold having a second molding surface for pressing the molten glass against the first molding surface. In the first molding surface, the surface roughness Ra of the peripheral portion which is in contact with the molten glass after pressing is higher than the surface roughness Ra of the central portion which is in contact with the molten glass before pressing.

Mold for glass substrate molding, method for producing glass substrate, method for producing glass substrate for information recording medium, and method for producing information recording medium

A method for manufacturing a glass substrate which has a uniform and minute pattern of stripes formed on the surface thereof by ultraprecision polishing, and which allows the recording capacity of a magnetic disk to be increased, includes an inspecting step before the glass substrate is subjected to ultraprecision polishing, whether the Young's modulus Es in topmost part as determined by the nanoindentation method and the Young's modulus Eg as determined by ultrasonic resonance fulfill the inequality 0.8 Eg&#x3c;Es&#x3c;1.2 Eg; or the hardness Hs in topmost part as determined by the nanoindentation method and the Vickers hardness Hv fulfill the inequality 0.8 Hv&#x3c;Hs&#x3c;1.2 Hv.

Method for fabricating a glass substrate, method for fabricating a magnetic disk, and magnetic disk

A method for fabricating a glass substrate containing SiOas a main ingredient thereof for an information recording medium which ensures removal of abrasive or foreign mater adhered to the glass substrate without complicating a cleaning step, involves, after a polishing step, keeping the surface of the glass substrate in contact with a liquid having a Si element elution in a range from 100 to 10 000 ppb/mmbefore a scrub-cleaning step.

Method for fabricating a glass substrate for an information recording medium, and magnetic disk using the same

Provided are a magnetic recording medium substrate whereupon a magnetic layer can be regularly formed in a recording area, a magnetic recording medium and a method for manufacturing the magnetic recording medium substrate. A plurality of recording areas wherein the magnetic layer is to be formed are formed on the surface of the disk-shaped magnetic recording medium substrate. The size of the recording area is an integral multiple of a lattice constant of a unit lattice of a single crystal structure constituting the magnetic layer. For instance, the width of a protruding section () to be used as the recording area is an integral multiple of the lattice constant of the unit lattice of the single crystal structure configuring the magnetic layer.

Magnetic recording medium substrate, magnetic recording medium, method for manufacturing magnetic recording medium substrate, and method for manufacturing magnetic recording medium

A method for cleaning a glass substrate which ensures removal of abrasive and other foreign matter without making a cleaning step complicated involves cleaning the glass substrate by scrubbing using two or more types of cleaning liquid having different Si element elution abilities. The cleaning liquid having the highest Si element elution is used first, and the cleaning liquid having the lowest Si element elution is used last.

Method for cleaning a glass substrate, method for fabricating a glass substrate, and magnetic disk using same

A method for fabricating a glass substrate containing SiOas a main ingredient thereof and having a uniform and minute pattern of stripes formed on the surface thereof by ultraprecision polishing includes a step of inspecting whether or not, at the topmost surface portion of the glass substrate after polishing, a given property of a bound energy of the Si atom with respect to the electrons occupying a 2P orbit as determined by XPS is equal to or less than a predetermined value, and the given property is a shift amount of the bound energy or a half-value width of the bound energy distribution, the predetermined value is 0.10 eV or 2.15 eV, respectively.

Method for fabricating a glass substrate, magnetic disk, and method for fabricating the same

The present invention relates to a glass substrate of which the outer periphery portion is unprocessed. The present invention also relates to a manufacturing method for a glass substrate of which the outer periphery portion is unprocessed, characterized in that a first lapping process, a second lapping process, a polishing process and a washing process are carried out after a press molding process is carried out so as to compress glass between an upper mold and a lower mold without regulating the edge surface of the outer periphery portion of the glass and, then, a crystallization process or an annealing process is carried out.

Growing community of inventors

Nishinomiya, Japan

Hideki Kawai