Magnetic recording medium supported on aromatic polyamide

In a magnetic recording medium the improvement which comprises a layer of magnetizable material and flexible support material of a high molecular weight p-oriented polycarbonamide consisting of at least about 70 mole % of recurring units of a formula selected from the group consisting of ##STR6## and mixtures thereof, wherein:

• X, Y, S' and Y' are monovalent radicals attached to a nuclear carbon and are selected from the group consisting of hydrogen, halogen, nitro and alkyl and alkoxy having from 1 to 3 carbon atoms, at least one of said X., Y, X' and Y' being halo, 0-30 mole % of other copolymeric units whenever present constituting such recurring units as m-phenylene ##STR7## urethane (--NHCOO--), urea (--NHCONH--), ester (--COO--), ether (--O--), and methylene (--CH.sub.2),
• said flexible material having a tensile modulus in excess of 800 kg/mm.sup.2 and up to 20,000 kg/mm.sup.2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25.degree. C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 .times. 10.sup.-5 mm/mm/% at least in one direction.

Magnetic recording medium comprising a layer of magnetizable material and a flexible support material of a high molecular weight p-oriented polycarbonamide consisting of at least about 70 mole % of recurring units of a formula selected from the group consisting of ##STR8## and mixtures thereof, wherein:

• X, Y, X' and Y' are monovalent radicals attached to a nuclear carbon and are selected from the group consisting of hydrogen, halogen, nitro and alkyl and alkoxy having from 1 to 3 carbon atoms, 0 - 30 mole % of other copolymeric units whenever present constituting such recurring units as m-phenylene ##STR9## urethane (--NHCOO--), urea (--NHCONH--), ester (--COO--), hydrazide (--CONHNH--), ether (--O), and aliphatic hydrocarbon groups (C.sub.1 - C.sub.3),
• said flexible material having a tensile modulus in excess of 800 kg/mm.sup.2 and up to 20, kg/mm.sup.2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25.degree. C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 .times. 10.sup.-5 mm/mm/% at least in one direction, said flexible support material being substantially free of organic solvent and inorganic ionic compounds, and having been prepared by heating to the polymer crystallization temperatures while preventing free shrinkage in the machine direction and in the transverse direction.