Magnetic recording medium supported on aromatic polyamide

Claim 2

Magnetic recording medium comprising a layer of magnetizable material and a flexible support material prepared from 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: ##STR4## 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 ##STR5## urethane (--NHCOO--), urea (--NHCONH--), ester (--COO--), hydrazide (--CONHNH--), ether (--O--), and aliphatic hydrocarbon groups (C 1 -C 3 ), said flexible material having a tensile modulus in excess of 800 kg/mm 2 and up to 20,000 kg/mm 2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25° C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 × 10 -5 mm/mm/% at least in one direction.

Claim 3

Magnetic recording medium of claim 1, wherein said flexible support material has a density of more than about 1.41 g/cm 3 and less than about 1.70 g/cm 3 at 25° C and 0% relative humidity.

Claim 4

Magnetic recording medium of claim 1, wherein said tensile modulus is in excess of 800 kg/mm 2 and of up to 10,000 kg/mm 2 in all directions on the plane.

Claim 5

Magnetic recording medium of claim 1, wherein said flexible support material has a thermal linear expansion coefficient of less than about 2.0 × 10 -5 mm/mm/° C at least in one direction.

Claim 6

Magnetic recording medium of claim 1, wherein said flexible support material has a tensile strength in excess of about 20 kg/mm 2 and up to about 150 kg/mm 2 in all directions on the film plane.

Claim 7

Magnetic recording medium of claim 1, wherein all of X, Y, X' and Y' are hydrogen.

Claim 8

Magnetic recording medium of claim 1, wherein at least one of X, Y, X', Y' is chlorine and the others are hydrogen.

Claim 9

Magnetic recording medium of claim 1, wherein the magnetizable material is a CrO 2 type compound.

Claim 10

Magnetic recording medium of claim 1, wherein said flexible support material consists essentially of at least about 95 mol % of said recurring units of said formula (I) and/or (II).

Claim 11

Magnetic recording medium of claim 9, wherein at least one of X, Y, X', Y' is chlorine and the others are hydrogen.

Claim 12

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 2 ), said flexible material having a tensile modulus in excess of 800 kg/mm 2 and up to 20,000 kg/mm 2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25° C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 × 10 -5 mm/mm/% at least in one direction.

Claim 13

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 2 ), said flexible material having a tensile modulus in excess of 800 kg/mm 2 and up to 20,000 kg/mm 2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25° C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 × 10 -5 mm/mm/% at least in one direction.

Claim 14

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 1 - C 3 ), said flexible material having a tensile modulus in excess of 800 kg/mm 2 and up to 20, kg/mm 2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25° C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 × 10 -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.

Claim 15

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 1 - C 3 ), said flexible material having a tensile modulus in excess of 800 kg/mm 2 and up to 20, kg/mm 2 at least in one direction, a water adsorption of less than 2.0 wt. % at 25° C and 75% relative humidity and a hydroscopic linear expansion coefficient of less than 1.0 × 10 -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.

Claim 16

Magnetic recording medium of claim 12, wherein said flexible support material has a density of more than about 1.41 g/cm 3 and less than about 1.70 g/cm 3 at 25° C and 0% relative humidity.

Claim 17

Magnetic recording medium of claim 12, wherein said tensile modulus is in excess of 800 kg/mm 2 and of up to 10,000 kg/mm 2 in all directions on the plane.

Claim 18

Magnetic recording medium of claim 12, wherein said flexible support material has a thermal linear expansion coefficient of less than about 2.0 × 10 -5 mm/mm/° C at least in one direction.

Claim 19

Magnetic recording medium of claim 12, wherein said flexible support material has a tensile strength in excess of about 20 kg/mm 2 and up to about 150 kg/mm 2 in all directions on the film plane.

Claim 20

Magnetic recording medium of claim 12, wherein all of X, Y, X' and Y' are hydrogen.

Claim 21

Magnetic recording medium of claim 12, wherein at least one of X, Y, X', Y' is chlorine and the others are hydrogen.

Claim 22

Magnetic recording medium of claim 12, wherein said flexible support material consists essentially of at least about 95 mole % of said recurring units of said Formula (I) and/or (II).