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Stabilized Flexible Films

IP.com Disclosure Number: IPCOM000081810D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bartkus, EA: AUTHOR [+4]

Abstract

Commercially available polymer films commonly used as magnetic media, substrates are usually biaxially oriented. Such films are anisotropic in their mechanical properties. When cut to circular disk shape and subjected to rotation, such films tend to become elliptical due to anisotropic creep. These techniques improve the dimensional stability of such films.

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Stabilized Flexible Films

Commercially available polymer films commonly used as magnetic media, substrates are usually biaxially oriented. Such films are anisotropic in their mechanical properties. When cut to circular disk shape and subjected to rotation, such films tend to become elliptical due to anisotropic creep. These techniques improve the dimensional stability of such films.

In one method, one or more polymer film disks are caused to spin about their center points. This generates centrifugal force which cause symmetrical radial stress on the disk. Simultaneously, the disk or disk are heated to an annealing temperature. The heat combined with the radial stress, causes polymer c-axis crystallites in each disk to align radially along the line of external stress. Subsequent cooling of the disks, while maintaining stress, results in recrystallized film having reduced anisotropy. Such film, when trimmed back to round and coated with magnetic material, provides a flexible magnetic disk having improve dimensional stability.

A similar result is achieved by securing a circular film disk aroun its circumference, and then simultaneously subjecting the film to annealing heat and radial stress. The stress is exerted by subjecting the film disk, as a diaphragm, to uniform pressure or vacuum, or a combination of pressure and vacuum. Alternatively, a mechanical center ram is applied to the disk. Any other means for exerting uniform radial stress on the disk can also be us...