Laminated Polymer Films With Isotropic InPlane Properties
Original Publication Date: 1979-May-01
Included in the Prior Art Database: 2005-Feb-20
The production of disks for high density recording applications requires quires a film which is much more nearly isotropic than biaxially-oriented polyethylene terephthalate (PET) film with respect to thermal expansion, hygroscopic expansion, long-term shrinkage, and mechanical properties. Such a film can be produced by laminating two or more plies of an oriented polymer film with the plies arrayed so as to produce a laminate with isotropic in-plane properties. In a two-ply laminate, the plies would like be oriented at 0 degrees and 90 degrees to each other. The plies could also be oriented at 0 degrees and 90 degrees to an experimentally determined extinction angle. In a three-ply laminate the plies are oriented at 0 degrees and plus 60 degrees and minus 60 degrees.