Patent ID: 8999533
Filing Date: 2015-04-07
Classification: C10M,C10N,G11B

Abstract:
1. A magnetic disk having at least a magnetic layer, a protective layer, and a lubricating layer provided in this order over a substrate, wherein the lubricating layer has properties of lowering the surface energy of the magnetic disk and enhancing the fluidity and CFT properties of the magnetic disk; wherein the lubricating layer is formed by a film of a lubricant c containing a lubricant a containing a compound represented by a chemical formula [in the formula, p and q are natural numbers] and a compound represented by a chemical formula [in the formula, m and n are natural numbers] and a lubricant b containing a compound represented by Chemical Formula 5 in which perfluoropolyether groups each having a perfluoropolyether main chain in a structure thereof and each having a hydroxyl group at an end thereof are bonded to each other through a divalent linking group having at least two hydroxyl groups in a structure thereof: wherein Rf represents —(OC 2 F 4 )m(OCF 2 )n- and m and n each represents an integer of 1 or more; and wherein a weight-average molecular weight (Mw) of the lubricant a is in a range of 3000 to 7000, a number-average molecular weight (Mn) of the lubricant b is in a range of 1000 to 6000, and a weight ratio of the lubricant a:the lubricant b in the lubricant c is 4:6 to 6:4.