Magnetic recording medium supported on aromatic polyamide
First Claim
1. 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 (C1 -C3),said flexible material having a tensile modulus in excess of 800 kg/mm2 and up to 20,000 kg/mm2 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.
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Abstract
An improved magnetic recording medium comprising a flexible support consisting of at least about 70 mol % of p-oriented aromatic polycarbonamide units. The polycarbonamide may include substituent groups on the aromatic nuclei. The support has a density of more than about 1.41 g/cm3 at 25° C and 0% relative humidity, and a tensile modulus higher than about 800 kg/mm2 in at least one direction, combined with a thin layer of magnetically susceptible material deposited electrically or dispersed in a nonmagnetic binder. The magnetic recording medium in this invention shows excellent running performance and has superior dimensional stability both thermally and hygroscopically.
115 Citations
19 Claims
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1. 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 (C1 -C3),said flexible material having a tensile modulus in excess of 800 kg/mm2 and up to 20,000 kg/mm2 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- ##STR4## and mixtures thereof, wherein;
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11. 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 (--CH2),
said flexible material having a tensile modulus in excess of 800 kg/mm2 and up to 20,000 kg/mm2 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.
- 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 (--CH2),
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12. 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 (C1 - C3),
said flexible material having a tensile modulus in excess of 800 kg/mm2 and up to 20, kg/mm2 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. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
- 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 (C1 - C3),
Specification