Aromatic polyamide film and magnetic recording medium using the

Details Aromatic polyamide film and magnetic recording medium using the Aromatic polyamide film and magnetic recording medium using the

1998-11-24

2000-08-01

Pianalto, Bernard

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

Physical dimension specified

428409, 4284735, 428694R, 428543, 428900, B32B 904, H01F 1002, G11B 566, G11B 570

Patent

active

060964197

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an aromatic polyamide film and to a magnetic recording medium using the film.


BACKGROUND ART

Aromatic polyamide films are being investigated for a variety of uses which will allow benefit from advantages such as their heat-resistance and mechanical properties. In particular, para-oriented aromatic polyamides are superior to other polymers with respect to mechanical properties such as stiffness and strength and the like, so that they offer great advantage in making films thinner and they are also being investigated for use in printer ribbons, magnetic tapes, condensers and the like. With regard to magnetic recording media, these are disclosed in Japanese Unexamined Patent Publication No. 58-168655 and Japanese Unexamined Patent Publication No. 62-112218 and the like.
In the field of magnetic recording media, a metallic-thin-film-type magnetic recording medium seems to be showing promise in increasing recording density, wherein Co, Ni, Cr, or the like, is deposited on a substrate film by vacuum evaporation deposition, cathode sputtering, ion plating or the like to form the metallic-thin-film-type magnetic recording medium. The metallic-thin-film-type magnetic recording medium cannot only increase recording density in the film but can also make a magnetic layer thinner, so that the entire thickness of the recording medium becomes thin and the film can be made longer. The metallic-thin-film-type magnetic recording medium, therefore, is very useful in increasing storage capacity.
A heat-resistant film is useful for reducing damage caused by heat, because the magnetic recording medium is heated at the deposition of the magnetic layer. However, the film curls greatly, so that it is difficult to uncurl. To address this problem, for example, there is disclosed in Japanese Unexamined Patent Publication No. 56-16938 a range of heat-shrinkage rates which are necessary for uncurling the film at high temperature. It has, however, been clear that the above-disclosed range is not satisfactory in reproducibly providing a smooth magnetic tape.
An object of the present invention is to address the problem described above and to provide an aromatic polyamide film for reproducibly producing a smooth magnetic recording medium and a magnetic recording medium using the film while utilizing its high degree of stiffness and its heat-resistance.


DISCLOSURE OF INVENTION

The present invention provides an aromatic polyamide film wherein the heat-shrinkage rate is 0.2 to 8% in the TD direction at 220.degree. C. under a load of 80 kg/cm.sup.2 and the average ten-point roughness Rz on the surface that is opposite the surface for providing a magnetic layer is 10 to 200 nm, and also provides a magnetic recording medium wherein the magnetic layer is deposited on one surface of the film.


BEST MODE FOR CARRYING OUT THE INVENTION

An aromatic polyamide in accordance with the present invention preferably contains a repeating unit represented by the general formula (I) and/or (II) at not less than 50 mole percent, and more preferably not less than 70 mole percent; ##STR1## the general formula (II) ##STR2## wherein examples of Ar.sub.1, Ar.sub.2, and Ar.sub.3 are illustrated as follows; ##STR3## X and Y are selected from the group consisting of --O--, --CH.sub.2 --, --CO--, --SO.sub.2 --, --S--, and --C(CH.sub.3).sub.2 --, but they are not to be limited thereto. Further, some hydrogen atoms on the aromatic rings may have a substituent selected from the group consisting of a halogen group (particularly chlorine), a nitro group, an alkyl having from 1 to 3 carbon atoms (particularly methyl), and an alkoxy having from 1 to 3 carbon atoms. Still further, a hydrogen in an amide bond which form a polymer may have other substituents.
Characteristically, the polymers preferably contain above-described aromatic rings linked in para-oriented of not less than 50%, and more preferably not less than 70%, to obtain a high degree of stiffness and high heat-resistance of the film. Additionally, in order to

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