Magnetic Disk Substrate and Production Method of Magnetic Disk

Abstract

When glass substrate is polished by using a polishing carrier, this invention provides a production method of a magnetic disk substrate that can be applied irrespective of shape, material and hardness of a polishing carrier and can prevent the occurrence of scratches on an outer end face of the glass substrate, a magnetic disk glass substrate obtained by such a method and having excellent characteristics, a production method of a magnetic disk characterized in that a magnetic recording layer is formed on such a magnetic disk glass substrate, and a magnetic disk. When glass of the glass substrate contains alkali metals, the invention can prevent the occurrence of protrusions that may result from the movement of sodium ions and lithium ions, on a magnetic film, a protective film, and so forth. When a glass substrate is polished while held by a polishing carrier, the polishing is carried out by using a polishing carrier, the inner surface of which can come into contact with an outer end face of the glass substrate and is resin coated.

1 . A production method of a magnetic disk substrate by polishing a glass substrate by holding said glass substrate by a polishing carrier, characterized in that polishing is carried out by using a polishing carrier in which an inner surface capable of coming into contact with an outer end face of the glass substrate is coated with a resin.  
     
     
         2 . The production method of a magnetic disk substrate according to  claim 1 , wherein said resin is a thermoplastic or thermosetting resin.  
     
     
         3 . The production method of a magnetic disk substrate according to  claim 2 , wherein said thermoplastic resin is a polyester, polyamide, polyolefin, ABS or polystyrene resin.  
     
     
         4 . The production method of a magnetic disk substrate according to  claim 2 , wherein said thermosetting resin is an epoxy, phenol, unsaturated polyester or polyimide resin.  
     
     
         5 . The production method of a magnetic disk substrate according to  claim 1 , wherein said resin is not fiber reinforced.  
     
     
         6 . The production method of a magnetic disk substrate according to  claim 1 , wherein a thickness of said resin coating is 10 μm to 1 mm.  
     
     
         7 . The production method of a magnetic disk substrate according to  claim 1 , wherein said polishing carrier is formed of a fiber reinforced resin.  
     
     
         8 . The production method of a magnetic disk substrate according to  claim 1 , wherein glass of said glass substrate is glass containing an alkali metal.  
     
     
         9 . The production method of a magnetic disk substrate according to  claim 8 , wherein said alkali metal is lithium.  
     
     
         10 . A production method of a magnetic disk characterized in that a magnetic recording layer is formed on said magnetic disk substrate according to  claim 1 .  
     
     
         11 . A glass substrate polishing carrier formed of a fiber reinforced resin, characterized in that an inner surface thereof capable of coming into contact with an outer end face of a glass substrate is resin coated.  
     
     
         12 . A magnetic disk substrate produced by using a production method of a magnetic disk substrate according to  claim 1 , wherein the total of scratches on an outer end face, observed when an entire circumference of the outer end face is observed through an optical microscope having a magnification of 120×, is not greater than 100.