Magnetic recording disk and process for manufacture thereof
View Patent ↗A magnetic recording disk has a high-adhesion lubricant layer that permits an operation at an extremely low level of flying height of 12 nm or less without troubles and which is capable of preventing the migration at a high-speed rotation, and comprises a substrate, a magnetic layer formed on the substrate, a protective layer formed on the magnetic layer and a lubricant layer formed on the protective layer, the lubricant layer containing a compound (A) of the general formula (I), wherein each of p and q is an integer of 1 or more, and a compound (B) having a perfluoropolyether main chain having two end moieties each of which contains a carbon atom or an oxygen atom to which a hydroxyl-containing hydrocarbon group that optionally contains ether bond(s) is bonded, and a process for the manufacture thereof is provided.
1. A magnetic recording disk comprising a substrate, a magnetic layer formed on the substrate, a protective layer formed on the magnetic layer and a lubricant layer formed on the protective layer, the lubricant layer containing a compound (A) of the general formula (I),
wherein each of p and q is an integer of 1 or more, and
a compound (B) having a perfluoropolyether main chain having two end moieties each of which contains a carbon atom or an oxygen atom to which a hydroxyl-containing hydrocarbon group that optionally contains an ether bond(s) is bonded.
2. The magnetic recording disk of claim 1 , wherein the compound (B) represents at least one compound selected from compounds of the general formulae (II), (III), (IV) and (VII),
HOCH 2 —CF 2 O—(CF 2 CF 2 O) a (CF 2 O) b —CH 2 OH (II)
HOCH 2 —CF 2 O—(CF 2 CF 2 O) a (CF 2 O) b —CF 2 —CH 2 OH (III)
HO—(CH 2 CH 2 —O) m —CH 2 —CF 2 —(OC 2 F 4 ) a (OCF 2 ) b —O—CF 2 —CH 2 —(OCH 2 CH 2 ) n —OH (VII)
wherein each of a, b, m and n is an integer of 1 or more.
3. The magnetic recording disk of claim 1 , wherein the lubricant layer contains the compound (A) and the compound (B) in a weight ratio of 2:8 to 8:2.
4. The magnetic recording disk of claim 1 , wherein the compound (A) has a weight average molecular weight (Mw) of 2,000 to 7,000 and has a polydispersity, represented by weight average molecular weight (Mw)/number average molecular weight (Mn), of 1.1 or less.
5. The magnetic recording disk of claim 1 , wherein the compound (B) has a weight average molecular weight (Mw) of 2,000 to 7,000 and has a polydispersity, represented by weight average molecular weight (Mn)/number average molecular weight (Mn), of 1.2 or less.
6. The magnetic recording disk of claim 1 , which is for a hard disk drive unit in a load unload method.
7. The magnetic recording disk of claim 1 , wherein said protective layer is a carbon-containing protective layer formed by a plasma CVD method.
8. The magnetic recording disk of claim 1 , said lubricant layer coats the surface of said protective layer and has a coverage ratio β of 0.85 to 1.
9. A magnetic recording disk comprising a substrate, a magnetic layer formed on the substrate, a protective layer formed on the magnetic layer and a lubricant layer formed on the protective layer, the lubricant layer being formed of a mixture of a compound (A) of the general formula (I),
wherein each of p and q is an integer of 1 or more, and
a compound (B) having a perfluoropolyether main chain having two end moieties containing a carbon atom or an oxygen atom to which a hydroxyl-containing hydrocarbon group that optionally contains ether bond(s) is bonded.
10. A process for the manufacture of a magnetic recording disk comprising a substrate, a magnetic layer formed on the substrate, a protective layer formed on the magnetic layer and a lubricant layer formed on the protective layer, the process comprising mixing a compound (A) of the general formula (I),
wherein each of p and q is an integer of 1 or more, with a compound (B) having a perfluoropolyether main chain having two end moieties containing a carbon atom or an oxygen atom to which a hydroxyl-containing hydrocarbon group that optionally contains ether bond(s) is bonded, and forming the said lubricant layer from the thus-obtained mixture.