Patent ID: 9177586
Filing Date: 2015-11-03
Classification: C10M,C10N,G11B

Abstract:
1. A magnetic disk comprising: a substrate; at least a magnetic layer, a protective layer, and a lubrication layer sequentially provided on the substrate, wherein the lubrication layer is a film formed by a lubricant that contains two types of compounds each having a perfluoropolyether main chain in its structure, wherein the two types of compounds includes a compound a having two or four hydroxyl groups in total at ends of a molecule of the compound a and a compound b, and wherein the compound b has a number average molecular weight that is smaller than the number average molecular weight of the compound a and not more than 1500; wherein a molecular weight distribution of the two types of compounds in total is within a range of 1 to 1.2; wherein a content of the compound b in the two types of compounds is not more than 10%; and wherein the compound b is selected from the group consisting of the following compounds represented by formula (1), formula (2), formula (3) and formula (4): wherein Rf represents —(OC