METHOD FOR PRODUCING GLASS SUBSTRATE FOR MAGNETIC DISK

• Main Authors: YOSHIDA KARA, ISHIDA MIZUHO
• Format: Patent
• Language: English
• Published: 05.11.2009
• Subjects: CHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUSENAMELS; CHEMISTRY; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS; GLASS; GRINDING; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; JOINING GLASS TO GLASS OR OTHER MATERIALS; MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; METALLURGY; MINERAL OR SLAG WOOL; PERFORMING OPERATIONS; PHYSICS; POLISHING; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS,MINERALS OR SLAGS; SURFACE TREATMENT OF GLASS; TOOLS FOR GRINDING, BUFFING, OR SHARPENING; TRANSPORTING

In the production of a glass substrate for magnetic disk, the present invention provides a method for producing a glass substrate for magnetic disk including a step of polishing a main surface of a circular glass substrate using a polishing pad made of a foamed resin while feeding a polishing liquid containing an abrasive, in which a polishing pad made of a foamed resin having an international rubber hardness of 45 IRHD or less, the hardness being measured at a dry state before contact with a slurry by the M method defined in JIS K6253, is used as a starting polishing pad and polishing is started after a polishing surface of the starting polishing pad is subjected to a dressing treatment to adjust the pad so that an open pore area ratio is 8% or more and an average circle equivalent diameter of open pores is 10 mum or more, in order to suppress an increase in roll-off in the polishing step of the main surface of the circular glass plate.