Magnetic recording medium incorporating fine acicular iron-based particles

Claim 2

MAGNETIC RECORDING MEDIUM EXHIBITING AN IMPROVED SIGNAL/NOISE RATIO COMPRISING AN MAGNETIZABLE LAYER CARRIED ON A NONMAGNETIZABLE SUPPORT THE MAGNETIZABLE LAYER COMPRISING A NONMAGNETIZABLE ORGANIC POLYMERIC BINDER MATERIAL, AND, UNIFORMLY THOROUGHLY AND COMPATIBLY DISPERSED IN THE BINDER MATERIAL, FINE ACICULAR FERROMAGNETIC PARTICLES THAT (1) COMPRISE AT LEAST ABOUT 75 WEIGHT-PERCENT METAL, AT LEAST A MAJORITY BY WEIGHT OF THE METAL BEING IRON AND ANY OTHER METAL INGREDIENT THAT COMPRISES AT LEAST 10 WEIGHT-PERCENT OF THE METAL BEING SELECTED FROM COBALT, NICKEL, AND CHROMIUM, (2) EXHIBIT A SATURATION MAGNETIC MOMENT OF AT LEAST 75 ELECTROMAGNETIC UNITS/GRAM, AND (3) EXHIBIT AN AVERAGE DIAMETER AND A SATURATION INTENSITY OF MAGNETIZATION ABOUT EQUAL TO OR LESS THAN THE COORDINATE VALUES FOR A POINT ON THE CURVE OF FIG.1; SUFFICIENT FERROMAGNETIC PARTICLES BEING INCLUDED SO THAT THE RECORDING MEDIUM EXHIBITS A REMANENT FLUX DENSITY GREATER THAN 1,500 GAUSS.

Claim 3

Magnetic recording medium of claim 1 in which said fine acicular ferromagnetic particles dispersed in the binder material comprise at least 80 weight-percent metal, exhibit a coercivity of at least 850 oersteds, and have a saturation magnetic moment of at least 100 electromagnetic units/gram.

Claim 4

Magnetic recording medium of claim 1 in which cobalt comprises between about 0.1 and 10 weight-percent of the metal ingredients.

Claim 5

Magnetic recording medium of claim 1 in which the ferromagnetic particles exhibit an average diameter and a saturation intensity of magnetization about equal to or less than the co-ordinate values for a point on the curve of FIG. 2.

Claim 6

Magnetic recording tape comprising a magnetizable layer carried on a nonmagnetizable support, the magnetizable layer comprising a nonmagnetizable organic polymeric binder material and, uniformly thoroughly and compatibly dispersed in the binder material, fine acicular ferromagnetic particles that (1) comprise at least about 80 weight-precent metal, at least a majority by weight of the metal being iron and any other metal ingredient that comprises at least 10 weight-percent of the metal being selected from cobalt, nickel, and chromium, (2) exhibit a saturation magnetic moment of at least 100 electromagnetic units/gram, (3) exhibit a coercivity of at least 850 oersteds, and (4) exhibit an average diameter and a saturation intensity of magnetization about equal to or less than the coordinate values for a point on the curve of FIG. 1; sufficient ferromagnetic particles being included so that the recording tape exhibits a remanent flux density greater than 2,000 gauss, and the recording tape exhibiting when measured as herein described a signal/noise ratio at least 6 decibels better than that of the standard gamma-ferric-oxide recording tape described herein.

Claim 7

Magnetic recording tape comprising a magnetizable layer carried on a nonmagnetizable support, the magnetizable layer comprising a nonmagnetizable organic polymeric binder material and, uniformly thoroughly and compatibly dispersed in the binder material, fine acicular ferromagnetic particles that (1) comprise at least about 80 weight-precent metal, at least a majority by weight of the metal being iron and any other metal ingredient that comprises at least 10 weight-percent of the metal being selected from cobalt, nickel, and chromium, (2) exhibit a saturation magnetic moment of at least 100 electromagnetic units/gram, (3) exhibit a coercivity of at least 850 oersteds, and (4) exhibit an average diameter and a saturation intensity of magnetization about equal to or less than the coordinate values for a point on the curve of FIG. 1; sufficient ferromagnetic particles being included so that the recording tape exhibits a remanent flux density greater than 2,000 gauss, and the recording tape exhibiting when measured as herein described a signal/noise ratio at least 6 decibels better than that of the standard gamma-ferric-oxide recording tape described herein.

Claim 8

Magnetic recording medium comprising a magnetizable layer carried on a nonmagnetizable support, the magnetizable layer comprising a nonmagnetizable organic polymeric binder material and, uniformly thoroughly and compatibly dispersed in the binder material, fine acicular ferromagnetic particles that (1) comprise at least about 80 weight-percent metal, at least about 75 weight-percent of the metal being iron and between about 0.1 and 10 weight-percent of the metal being cobalt; (2) have an average diameter of less than about 450 angstroms; (3) have a saturation magnetic moment of at least 100 electromagnetic units/gram, and (4) exhibit an average diameter and a saturation intensity of magnetization about equal to or less than the co-ordinate values for a point on the curve of FIG. 1; sufficient ferromagnetic particles being included so that the recording medium exhibits a remanent flux density of greater than 2,000 gauss, and the recording medium exhibiting when measured as herein described a signal/noise ratio at least 6 decibels better than that of the standard gamma-ferric-oxide recordiNg medium described herein.

Claim 9

Magnetic recording medium comprising a magnetizable layer carried on a nonmagnetizable support, the magnetizable layer comprising a nonmagnetizable organic polymeric binder material and, uniformly thoroughly and compatibly dispersed in the binder material, fine acicular ferromagnetic particles that (1) comprise at least about 80 weight-percent metal, at least about 75 weight-percent of the metal being iron and between about 0.1 and 10 weight-percent of the metal being cobalt; (2) have an average diameter of less than about 450 angstroms; (3) have a saturation magnetic moment of at least 100 electromagnetic units/gram, and (4) exhibit an average diameter and a saturation intensity of magnetization about equal to or less than the co-ordinate values for a point on the curve of FIG. 1; sufficient ferromagnetic particles being included so that the recording medium exhibits a remanent flux density of greater than 2,000 gauss, and the recording medium exhibiting when measured as herein described a signal/noise ratio at least 6 decibels better than that of the standard gamma-ferric-oxide recordiNg medium described herein.

Claim 10

Magnetic recording medium of claim 6 in which the ferromagnetic particles exhibit an average diameter and a saturation intensity of magnetization about equal to or less than the co-ordinate values for a point on the curve of FIG. 2.