Flattening film forming composition for hard disk

Abstract

A flattening film forming composition for a hard disk that can prevent a magnetic material from migrating to the nonmagnetic layer, including a photopolymerizable coating material containing at least one polymer selected from a homopolymer that has a divinyl aromatic compound-derived unit structure and a copolymer having the unit structure or containing a mixture of the polymer and a photopolymerizable compound. The photopolymerizable compound may include an acrylate group, a methacrylate group, or a vinyl group. The polymer may be a copolymer further containing an addition polymerizable compound as a component to be copolymerized. A method for producing a hard disk, including: a first step of forming projections and recesses on a magnetic body; a second step of coating the projections and recesses with the flattening film forming composition; and a third step of flattening the coating by means of etching and exposing a surface of the magnetic body.

Dependencies are inferred from the claim text.