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Lamination of Polymer Films to Produce Isotropic In Plane Properties

IP.com Disclosure Number: IPCOM000088109D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Blumentritt, BF: AUTHOR

Abstract

Flexible recording media are commonly composed of a poly (ethylene terephthalate) film substance, hereafter referred to as PET, which has been coated with magnetic particles in a polymeric binder. In flexible disk media, anisotropy of mechanical properties, expansion coefficients and dimensional changes over extended periods of time limit the recording density.

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Lamination of Polymer Films to Produce Isotropic In Plane Properties

Flexible recording media are commonly composed of a poly (ethylene terephthalate) film substance, hereafter referred to as PET, which has been coated with magnetic particles in a polymeric binder. In flexible disk media, anisotropy of mechanical properties, expansion coefficients and dimensional changes over extended periods of time limit the recording density.

Films more nearly isotropic than oriented PET may be produced by laminating two plies of biaxially-oriented PET film so that the crystalline and amorphous orientation in one ply tends to average with the orientation in the second ply. The figure shows a PET film 3 extending from an extrusion die 4 and biaxially oriented by a series of rolls 5 and a tenter frame (not shown). The crystalline orientation of the film is indicated by the arrows 6. The sheet of film 3 is slit to produce three narrower continuous sheets 7, 8 and 9 which are accumulated on rolls 10, 11 and 12, respectively, while the marginal scrap 13 is removed. The films 7 and 9 from opposite marginal portions of sheet 3 are laminated together to produce a continuous film which is more nearly isotropic than the single ply film, but which is similar to the single ply film in most other respects.

A two-ply film, as described, is not nearly as isotropic as a cross-ply laminate, but is low in cost and does not have the transverse joints and seams found in cross-ply films.

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