Magnetic recording medium having a perfluoropolyether polymer protective coating
AssigneeMinnesota Mining and Manufacturing Company
InventorsMario D. Burguette, George D. Foss
Life of this patent
Estimating the term…
Abstract
A magnetic recording medium protected by a very thin, composite low surface energy covering is disclosed. The covering comprises a primer layer of a polymerized phosphorylated monomer or oligomer and an outer lubricant layer of perfluoropolyether polymer. The two layers may be polymerized in situ. The primer layer is made from monomers such as phosphorylated bis[4-methacryloyloxyhydroxypropylcarbamato-cyclohexyl]methane. The outer layer is made from a polymerizable perfluoropolyether monomer such as ##STR1## The composite low surface energy covering is especially useful for providing lubricity and corrosion resistance to a metallic thin-film magnetic recording coating.
Claims17
A substrate, a surface of which is covered by a protective coating present in an amount sufficient to lubricate said surface and comprising:
- (a) a primer layer comprising a polymer made from a phosphorylated monomer or oligomer which is soluble in at least one common organic solvent and which contains at least one aromatic, cycloaliphatic or hetero atom moiety;
- and
- (b) an outer layer comprising a polymer made from at least one perfluoropolyether comprising a plurality of perfluoroalkylene oxide repeating units.
A method of making a magnetic recording medium with a protective coating on the surface of the magnetizable coating of said medium, comprising the steps of:
- (i) coating onto said surface a dilute solution of a polymerizable phosphorylated monomer or oligomer containing at least one aromatic, cycloaliphatic or hetero atom moiety, said solution being in a common organic solvent to provide a primer coating;
- (ii) coating over the primer coating a second dilute solution of perfluoropolyether monomer having an average of at least about 1.5 ethylenically unsaturated polymerizable sites per molecule and having the formula ##STR10## wherein Q comprises a polymerizable group attached to R.sub.f which represents a chain of one or more randomly distributed perfluoroalkylene oxide units selected from the group consisting of ##STR11## in which a is independently an integer of 1 to 4, k is the number of such repeating units having a value from 1 to 300 such that the segment R.sub.f preferably has a number average molecular weight of about 500 to 10,000, and Z is selected from the group consisting of --OC.sub.a F.sub.2a+1 and Q;
- (iii) drying said coatings;
- and
- (iv) polymerizing the dried coatings, the thickness of the resulting protective coating not exceeding 200 nm.
Dependencies are inferred from the claim text.