PROCESS FOR FORMING MAGNETIC RECORDING LAYER FOR TAPE MEDIA

A method, in one approach, includes forming a magnetic recording layer having: encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an encapsulating layer, and a polymeric binder binding the encapsulated nanoparticles. 1. A method , comprising: encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an encapsulating layer, and', 'a polymeric binder binding the encapsulated nanoparticles., 'forming a magnetic recording layer having2. The method as recited in claim 1 , wherein forming the recording layer includes spray coating a mixture of the unencapsulated magnetic nanoparticles claim 1 , an aromatic polymer claim 1 , and the polymeric binder onto a structure.3. The method as recited in claim 1 , wherein forming the recording layer includes heating the magnetic nanoparticles and an aromatic polymer to a temperature of at least 200 degrees Celsius; mixing the polymeric binder with the heated magnetic nanoparticles claim 1 , the aromatic polymer claim 1 , and a solvent to form a mixture; applying the mixture onto a structure; at least partially drying the applied mixture; and radiating the at least partially dried applied mixture for causing crosslinking of the polymeric binder.4. The method as recited in claim 3 , wherein the polymeric binder includes an acrylic terminated polyester.5. The method as recited in claim 1 , wherein forming the recording layer includes radiating a mixture comprising the magnetic nanoparticles and an aromatic polymer for causing the aromatic polymer to crosslink claim 1 , thereby forming the encapsulating layer around the magnetic nanoparticles.6. (canceled)7. (canceled)8. The method as recited in claim 1 , wherein an average diameter of the magnetic nanoparticles is in a range of 2 nanometers to 20 nanometers.9. The method as recited in claim 1 , wherein the encapsulating layer is a layer selected from the group consisting of: a polyaromatic film claim 1 , and graphite-like ...

HEXAGONAL STRONTIUM FERRITE POWDER, MAGNETIC RECORDING MEDIUM, AND MAGNETIC RECORDING AND REPRODUCING APPARATUS

A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4.000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium. 1. A hexagonal strontium ferrite powder ,wherein an average particle size is 10.0 to 25.0 nm,a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, anda coercivity Hc is greater than 2,000 Oe and smaller than 4,000 Oe.2. The hexagonal strontium ferrite powder according to claim 1 , which is a ferromagnetic powder for magnetic recording.3. The hexagonal strontium ferrite powder according to claim 1 ,{'sup': '2', '#text': 'wherein a mass magnetization σs is equal to or greater than 41 A·m/kg.'}4. The hexagonal strontium ferrite powder according to claim 1 ,wherein the content of the one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 12.0 atom % with respect to 100.0 atom % of an iron atom.5. The hexagonal strontium ferrite powder according to claim 1 , comprising:a gallium atom.6. The hexagonal strontium ferrite powder according to claim 4 , comprising:a gallium atom.7. The hexagonal strontium ferrite powder according to claim 1 , comprising:a scandium atom.8. The hexagonal strontium ferrite powder according to claim 4 , ...

Composition for magnetic recording medium and magnetic recording medium

The magnetic coating composition for a magnetic recording medium comprises: (A) a compound denoted by formula (1) having a weight average molecular weight of equal to or less than 20,000: (A 1 -R 2 —S)n-R 1 —(P 1 )m   (1) wherein, in formula (1), R 1 denotes an organic connecting group with a valence of (m+n); R 2 denotes a single bond or divalent organic connecting group; A 1 denotes a functional group selected from the group consisting of an acidic group, a basic group, and a hydroxyl group; m denotes an integer ranging from 1 to 8 and n denotes an integer ranging from 1 to 9, with m+n ranging from 3 to 10; each of n instances of A 1 and R 2 can be independently different or identical; P 1 denotes a polymer backbone; and m instances of P 1 can be identical or different; (B) binder; (C) ferromagnetic powder; and (D) solvent.

METAL OXIDE PARTICLE DISPERSION FOR MANUFACTURING PARTICULATE MAGNETIC RECORDING MEDIUM, METHOD OF MANUFACTURING MAGNETIC LAYER-FORMING COMPOSITION OF PARTICULATE MAGNETIC RECORDING MEDIUM AND METHOD OF MANUFACTURING PARTICULATE MAGNETIC RECORDING MEDIUM

The metal oxide particle dispersion for manufacturing a particulate magnetic recording medium contains metal oxide particles, solvent, and a polyester compound having one or more groups selected from the group consisting of a carboxyl group and a salt thereof, a phosphoric acid group and a salt thereof, a hydroxyl group and a nitrogen-substituted alkylene group, but substantially not containing ferromagnetic powder. 1. A metal oxide particle dispersion ,which is a metal oxide particle dispersion for manufacturing a particulate magnetic recording medium, and comprises:metal oxide particles;solvent; anda polyester compound comprising one or more groups selected from the group consisting of a carboxyl group and a salt thereof, a phosphoric acid group and a salt thereof, a hydroxyl group and a nitrogen-substituted alkylene group, but substantially not comprising ferromagnetic powder.2. The metal oxide particle dispersion according to claim 1 ,wherein the polyester compound comprises one or more groups selected from the group consisting of a carboxyl group and a salt thereof, a phosphoric acid group and a salt thereof, and a nitrogen-substituted alkylene group.3. The metal oxide particle dispersion according to claim 1 ,wherein a weight average molecular weight of the polyester compound is greater than or equal to 1,000 but less than or equal to 20,000.4. The metal oxide particle dispersion according to claim 1 ,wherein a weight average molecular weight of the polyester compound is greater than or equal to 1,000 but less than or equal to 10,000.5. The metal oxide particle dispersion according to claim 1 ,wherein the polyester compound comprises a polyester compound comprising a nitrogen-substituted alkylene group, with the polyester compound comprising a nitrogen-substituted alkylene group being a polyalkyleneimine compound.7. The metal oxide particle dispersion according to claim 6 ,wherein Z in formula (1) denotes a reactive residue of a carboxylic anhydride.8. The ...

Magnetic recording medium

The magnetic recording medium includes a magnetic layer containing a ferromagnetic powder and a binder on a nonmagnetic support, wherein the ferromagnetic powder is an ε-iron oxide powder, and the magnetic layer comprises a compound comprising at least one substituent selected from the group consisting of a hydroxyl group and a quaternary ammonium salt group.

Magnetic recording medium

The magnetic recording medium comprises protrusions on a surface of a magnetic layer such that when protrusions of equal to or more than 8 nm in height as measured by AFM on the surface of the magnetic layer are divided into protrusions A formed of a spherical material and protrusions B formed of a non-spherical material, a value a, obtained by adding three times a standard deviation σ of heights of protrusions A to an average value of the heights of protrusions A, a value b, obtained by adding three times a standard deviation σ of heights of protrusions B to an average value of the heights of protrusions B, and a difference c, obtained by subtracting b from a, are calculated, conditions 13 nm≦a≦25 nm, 13 nm≦b≦25 nm, and 0.0 nm≦c≦10 nm are satisfied.

Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus

The magnetic tape includes a non-magnetic support and a magnetic layer including ferromagnetic powder and a binding agent, in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference (L99.9−L0.1) between a value L99.9 of a cumulative distribution function of 99.9% and a value L0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and an isoelectric point of a surface zeta potential of the magnetic layer is 3.8 or less.

MAGNETIC RECORDING MEDIUM

An aspect of the present invention relates to a magnetic recording medium comprising a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein the magnetic layer and/or nonmagnetic layer comprises organic acid A and organic acid B below, with an acid strength pKa(A) of organic acid A and an acid strength pKa(B) of organic acid B satisfying a relation of pKa(A) Подробнее

HEXAGONAL STRONTIUM FERRITE POWDER, MAGNETIC RECORDING MEDIUM, AND MAGNETIC RECORDING AND REPRODUCING APPARATUS

A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4,000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium. 1. A hexagonal strontium ferrite powder ,wherein an average particle size is 10.0 to 25.0 nm,a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, anda coercivity Hc is greater than 2,000 Oe and smaller than 4,000 Oe.2. The hexagonal strontium ferrite powder according to claim 1 , which is a ferromagnetic powder for magnetic recording.3. The hexagonal strontium ferrite powder according to claim 1 ,{'sup': '2', 'wherein a mass magnetization as is equal to or greater than 41 A·m/kg.'}4. The hexagonal strontium ferrite powder according to claim 1 ,wherein the content of the one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 12.0 atom % with respect to 100.0 atom % of an iron atom.5. The hexagonal strontium ferrite powder according to claim 1 , comprising:a gallium atom.6. The hexagonal strontium ferrite powder according to claim 4 , comprising:a gallium atom.7. The hexagonal strontium ferrite powder according to claim 1 , comprising:a scandium atom.8. The hexagonal strontium ferrite powder according to claim 4 , comprising ...

MAGNETIC TAPE

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a center line average surface roughness Ra measured regarding the surface of the magnetic layer is equal to or smaller than 1.8 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer includes an abrasive, and a tilt cos θ of the ferromagnetic hexagonal ferrite powder with respect to a surface of the magnetic layer acquired by cross section observation performed by using a scanning transmission electron microscope is 0.85 to 1.00. 1. A magnetic tape comprising:a non-magnetic support; anda magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support,wherein a center line average surface roughness Ra measured regarding the surface of the magnetic layer is equal to or smaller than 1.8 nm,a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050,the ferromagnetic powder is ferromagnetic hexagonal ferrite powder,the magnetic layer includes an abrasive, anda tilt cos θ of the ferromagnetic hexagonal ferrite powder with respect to a surface of the magnetic layer acquired by cross section observation performed by using a scanning transmission electron microscope is 0.85 to 1.00.2. The magnetic tape according to claim 1 ,wherein the logarithmic decrement is 0.010 to 0.050.3. The magnetic tape according to claim 1 ,wherein the center line average surface roughness Ra is 1.2 nm to 1.8 nm.4. The magnetic tape according to claim 2 ,wherein the center line average surface roughness Ra is 1.2 nm to 1.8 nm.5. The magnetic tape according to claim 1 , further comprising:a non-magnetic layer including non- ...

MAGNETIC TAPE DEVICE AND MAGNETIC REPRODUCTING METHOD

The magnetic tape device includes a magnetic tape; and a reproducing head, in which the reproducing head is a TMR head, a center line average surface roughness Ra measured regarding a surface of the magnetic layer of the magnetic tape is equal to or smaller than 2.0 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and a ratio (Sdc/Sac) of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30. 1. A magnetic tape device comprising:a magnetic tape; anda reproducing head,wherein the reproducing head is a magnetic head including a tunnel magnetoresistance effect type element as a reproducing element,the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support,a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm,a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, anda ratio Sdc/Sac of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.2. The magnetic tape device according to claim 1 ,wherein the logarithmic decrement is 0.010 to 0.050.3. The magnetic tape device according to claim 1 ,wherein the center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 2.0 nm.4. The magnetic tape device according to claim 2 ,wherein the center line average surface roughness Ra ...

MAGNETIC TAPE DEVICE AND HEAD TRACKING SERVO METHOD

The magnetic tape device includes a magnetic tape; and a servo head, in which the servo head is a TMR head, the magnetic tape includes a servo pattern in the magnetic layer, a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and a ratio (Sdc/Sac) of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster thereof in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30. 1. A magnetic tape device comprising:a magnetic tape; anda servo head,wherein the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element,the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support,the magnetic layer includes a servo pattern,a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm,a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, anda ratio Sdc/Sac of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.2. The magnetic tape device according to claim 1 ,wherein the logarithmic decrement is 0.010 to 0.050.3. The magnetic tape device according to claim 1 ,wherein the center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.2 nm to 2.0 nm.4. The magnetic tape device according to ...

Magnetic tape device and magnetic reproducing method

The magnetic tape device includes a TMR head as a reproducing head; and a magnetic tape which includes a non-magnetic support, and a magnetic layer including ferromagnetic hexagonal ferrite powder and a binding agent on the non-magnetic support, an XRD intensity ratio (Int(110)/Int(114)) of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00, a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, and a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050.

Magnetic tape

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 1.8 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and a contact angle with respect to 1-bromonaphthalene measured regarding the surface of the magnetic layer is 45.0° to 55.0°.

MAGNETIC TAPE, MAGNETIC TAPE CARTRIDGE, AND MAGNETIC TAPE APPARATUS

The magnetic tape includes a non-magnetic support; and a magnetic layer, in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L−Lbetween a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 or more and 0.40 or less. 1. A magnetic tape comprising:a non-magnetic support;a magnetic layer including ferromagnetic powder;a non-magnetic layer including non-magnetic powder between the non-magnetic support and the magnetic layer; anda back coating layer on a surface side of the non-magnetic support opposite to a surface side provided with the magnetic layer.wherein the magnetic layer has a timing-based servo pattern,wherein the ferromagnetic powder comprises hexagonal ferrite powder and/or r-iron oxide powder,{'sub': 99.9', '0.1', '99.9', '0.1, 'wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L−Lbetween a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and'}wherein an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 or more and 0.40 or less.2. The magnetic tape according to claim 1 ,wherein a difference Nxy−Nz between the refractive ...

MAGNETIC TAPE, MAGNETIC TAPE CARTRIDGE, AND MAGNETIC TAPE APPARATUS

The magnetic tape includes a non-magnetic support and a magnetic layer including ferromagnetic powder and a binding agent, in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference (L−L) between a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and an isoelectric point of a surface zeta potential of the magnetic layer is 3.8 or less. 1. A magnetic tape comprising:a non-magnetic support; anda magnetic layer including ferromagnetic powder and a binding agent,wherein the magnetic layer has a timing-based servo pattern,{'sub': 99.9', '0.1', '99.9', '0.1, 'wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L−Lbetween a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and'}wherein an isoelectric point of a surface zeta potential of the magnetic layer is 3.8 or less.2. The magnetic tape according to claim 1 ,wherein the isoelectric point is 2.5 or more and 3.8 or less.3. The magnetic tape according to claim 1 ,wherein the binding agent is a binding agent containing an acidic group.4. The magnetic tape according to claim 3 ,wherein the acidic group includes at least one type of acidic group selected from the group consisting of a sulfonic acid group and a salt thereof.5. The magnetic tape according to claim 1 ,wherein the timing-based servo pattern is a linear servo pattern which continuously extends from one side of the magnetic tape in a width direction to the other side thereof and is inclined at an angle α with ...

MAGNETIC TAPE, MAGNETIC TAPE CARTRIDGE, AND MAGNETIC TAPE APPARATUS

The magnetic tape includes a non-magnetic support; and a magnetic layer, in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L−Lbetween a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 or more and 0.40 or less. 1. A magnetic tape comprising:a non-magnetic support; anda magnetic layer including ferromagnetic powder and a binding agent,wherein the magnetic layer has a timing-based servo pattern,{'sub': 99.9', '0.1', '99.9', '0.1, 'wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L−Lbetween a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and'}wherein an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 or more and 0.40 or less.2. The magnetic tape according to claim 1 ,wherein a difference Nxy−Nz between the refractive index Nxy and the refractive index Nz is 0.25 or more and 0.40 or less.3. The magnetic tape according to claim 1 ,wherein the timing-based servo pattern is a linear servo pattern which continuously extends from one side of the magnetic tape in a width direction to the other side thereof and is inclined at an ...

MAGNETIC TAPE, MAGNETIC TAPE CARTRIDGE, AND MAGNETIC TAPE APPARATUS

The magnetic tape includes a non-magnetic support; and a magnetic layer in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference between a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and a difference between a spacing Smeasured on a surface of the magnetic layer by an optical interferometry after methyl-ethyl-ketone cleaning and a spacing Smeasured on the surface of the magnetic layer by an optical interferometry before methyl-ethyl-ketone cleaning is greater than 0 nm and 15.0 nm or less. w 1. A magnetic tape comprising:a non-magnetic support; anda magnetic layer including ferromagnetic powder and a binding agent,wherein the magnetic layer has a timing-based servo pattern,{'sub': 99.9', '0.1', '99.9', '0.1, 'wherein an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L−Lbetween a value Lof a cumulative distribution function of 99.9% and a value Lof a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and'}{'sub': after', 'before', 'after', 'before, 'wherein a difference S−Sbetween a spacing Smeasured on a surface of the magnetic layer by an optical interferometry after methyl-ethyl-ketone cleaning and a spacing Smeasured on the surface of the magnetic layer by an optical interferometry before methyl-ethyl-ketone cleaning is greater than 0 nm and 15.0 nm or less.'}2. The magnetic tape according to claim 1 ,{'sub': after', 'before, 'wherein the difference S−Sis 2.0 nm or more and 15.0 nm or less.'}3. The magnetic tape according to claim 1 ,{'sub': after', 'before, 'wherein the ...

MAGNETIC RECORDING MEDIUM, MAGNETIC RECORDING AND REPRODUCING DEVICE AND COMPOSITION FOR MAGNETIC RECORDING MEDIUM INCLUDING POLYALKYLENEIMINE COMPOUND

The magnetic recording medium includes: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the magnetic layer further includes a compound including a polyalkyleneimine chain and a vinyl polymer chain. The composition for a magnetic recording medium includes: ferromagnetic powder; and a compound including a polyalkyleneimine chain and a vinyl polymer chain. 1. A composition ,which is a composition for a magnetic recording medium, the composition comprising:a ferromagnetic powder; anda compound including a polyalkyleneimine chain and a vinyl polymer chain.2. The composition according to claim 1 ,wherein the compound includes a poly(meth)acrylate chain as the vinyl polymer chain.3. The composition according to claim 1 ,wherein a glass transition temperature Tg of the compound is 50° C. to 200° C.4. The composition according to claim 1 ,wherein an amine value of the compound is equal to or greater than 0.20 mmol/g.5. The composition according to claim 1 ,wherein a weight-average molecular weight of the compound is equal to or smaller than 30,000.6. The composition according to claim 1 , further comprising:a binding agent.7. The composition according to claim 1 ,wherein 0.5 to 50.0 parts by mass of the compound is included with respect to 100.0 parts by mass of the ferromagnetic powder.8. The composition according to claim 1 ,wherein the ferromagnetic powder is a hexagonal ferrite powder. This is a Continuation of application Ser. No. 16/360,758 filed Mar. 21, 2019 which claims priority under 35 U.S.C 119 to Japanese Patent Application No. 2018-054282 filed on Mar. 22, 2018 and Japanese Patent Application No. 2019-050156 filed on Mar. 18, 2019. Each of the above applications is hereby expressly incorporated by reference, in its entirety, into the present application.The present invention relates to a magnetic recording medium, a magnetic recording and reproducing device and a composition ...

MAGNETIC RECORDING MEDIUM AND COATING COMPOSITION FOR MAGNETIC RECORDING MEDIUM

An aspect of the present invention relates to a magnetic recording medium comprising a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein an average particle size of the ferromagnetic powder is equal to or less than 50 nm, the magnetic layer further comprises a compound, and the compound comprises at least one polyalkyleneimine chain and at least one polyester chain, with a proportion in the compound accounted for by the polyalkyleneimine chain being less than 5.0 weight percent and a number average molecular weight of the polyalkyleneimine chain ranging from 300 to 3,000.

MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING AND REPRODUCING DEVICE

The magnetic recording medium includes a non-magnetic support; a magnetic layer including a ferromagnetic powder on one surface of the non-magnetic support; and a back coating layer including a non-magnetic powder on the other surface of the non-magnetic support, in which a difference (S−S) between a spacing Smeasured by optical interferometry regarding a surface of the back coating layer after ethanol cleaning and a spacing Smeasured by optical interferometry regarding the surface of the back coating layer before ethanol cleaning is greater than 0 nm and equal to or smaller than 15.0 nm, and the non-magnetic support is an aromatic polyester support having a moisture absorption of 0.3% or less. 1. A magnetic recording medium comprising:a non-magnetic support;a magnetic layer including a ferromagnetic powder on one surface of the non-magnetic support; anda back coating layer including a non-magnetic powder on the other surface of the non-magnetic support,{'sub': after', 'before', 'after', 'before, 'wherein a difference (S−S) between a spacing Smeasured by optical interferometry regarding a surface of the back coating layer after ethanol cleaning and a spacing Smeasured by optical interferometry regarding the surface of the back coating layer before ethanol cleaning is greater than 0 nm and equal to or smaller than 15.0 nm, and the non-magnetic support is an aromatic polyester support having a moisture absorption of 0.3% or less.'}2. The magnetic recording medium according to claim 1 ,{'sub': after', 'before, 'wherein the difference (S−S) is 1.0 nm to 15.0 nm.'}3. The magnetic recording medium according to claim 1 ,{'sub': after', 'before, 'wherein the difference (S−S) is 2.0 nm to 13.0 nm.'}4. The magnetic recording medium according to claim 1 ,wherein the aromatic polyester support has a moisture absorption of 0.1% or more and 0.3% or less.5. The magnetic tape according to claim 1 , further comprising:a non-magnetic layer including a non-magnetic powder between the ...

Method of manufacturing magnetic recording medium and magnetic recording medium manufactured by the same

The present invention relates to a method of manufacturing a magnetic recording medium wherein the magnetic layer coating liquid comprising a ferromagnetic powder having an average particle size of 10 to 40 nm and a moisture content of 0.3 to 3.0 weight percent; a binder (a) comprising 0.2 to 0.7 meq/g of at least one polar group selected from the group consisting of —SO 3 M, —OSO 3 M, —PO(OM) 2 , —OPO(OM) 2 , and COOM (M denotes a hydrogen atom or the like) and having a weight average molecular weight of 20,000 to 200,000, and/or (b) comprising 0.5 to 5 meq/g of at least one polar group selected from the group consisting of —CONR 1 R 2 , —NR 1 R 2 , and —NR + R 1 R 2 R 3 (wherein R 1 , R 2 , and R 3 each independently denote a hydrogen atom or the like) and having a weight average molecular weight of 20,000 to 200,000; and a compound comprising at least one carboxyl group and/or hydroxyl group per molecule.

磁気記録媒体

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Magnetic recording media dispersants

Reactive dispersants for magnetic recording media are prepared by sequentially phosphating and esterifying or esterifying and phosphating alkoxylated alcohols having at least two carbon atoms and at least two hydroxyl groups. The phosphating agent can be phosphorus oxychloride while the esterifying agent can be acrylic acid.

Phosphated acrylates of alkoxylated alcohols

Reactive dispersants for magnetic recording media are prepared by sequentially phosphating and esterifying or esterifying and phosphating alkoxylated alcohols having at least two carbon atoms and at least two hydroxyl groups. The phosphating agent can be phosphorus oxychloride while the esterifying agent can be acrylic acid.

dispersing resins

Magnetic recording medium

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Magnetic recording medium

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Preparation of magnetic powder for magnetic recording

Magnetic powder and manufacture thereof

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Method of making magnetic recording media with a back layer

Die Erfindung betrifft ein Verfahren zur Herstellung von magnetischen Aufzeichnungsträgern mit einer Rückschicht geringer Schichtdicke durch Auftragen einer Dispersion aus nichtmagnetisierbaren Feststoffen in einer Lösung eines Polymerbindemittels in einem organischen Lösungsmittel auf die der Magnetschicht gegenüberliegende Seite des Trägermaterials wobei der Dispersion eine als Verdicker wirkende hochmolekulare organische Verbindung zugesetzt wird. The invention relates to a method for producing magnetic recording media with a backing layer of low layer thickness by applying a dispersion of non-magnetizable solids in a solution of a polymer binder in an organic solvent to the side of the carrier material opposite the magnetic layer, the dispersion being added to a high molecular weight organic compound which acts as a thickener becomes.

Magnetic recording medium and method for manufacturing the same

Magnetic recording medium and magnetic coating composition for magnetic recording medium

Magnetic recording medium

Magnetic recording medium

Magnetic recording medium

Polymeric masses suitable for use as dispersing resins for magnetic recording materials.

MAGNETIC RECORDING FLUID CONTAINING AS A DERIVATIVE OF N-ACYLSARCOSINE

L'invention concerne un fluide d'enregistrement magnétique, tel qu'une bande magnétique comportant un support sur lequel est appliqué un revêtement magnétisable contenant un liant à l'aide d'un dispersant. Comme dispersant est utilisé un dérivé de N-acylsarcosine. On obtient ainsi en peu de temps une dispersion optimale du pigment dans le liant. Un excès de dispersant agit comme lubrifiant pendant la migration. Le groupe acyle contient de préférence une chaîne d'hydrocarbure aliphatique ou oléfinique comptant 12 à 22 atomes de carbone. On préfère utiliser des sels de N-acylsarcosine, notamment des sels métalliques, des sels des métaux alcalins, des sels alcalino-terreux et des sels d'amine. Application : bande magnétique. The invention relates to a magnetic recording fluid, such as a magnetic tape having a support to which is applied a magnetizable coating containing a binder using a dispersant. As dispersant is used a derivative of N-acylsarcosine. An optimum dispersion of the pigment in the binder is thus obtained in a short time. An excess of dispersant acts as a lubricant during migration. The acyl group preferably contains an aliphatic or olefinic hydrocarbon chain having 12 to 22 carbon atoms. It is preferred to use salts of N-acylsarcosine, especially metal salts, alkali metal salts, alkaline earth salts and amine salts. Application: magnetic tape.

Patent FR2388362B1

Magnetic recording medium

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Magnetic recording medium having a magnetic layer prepared from magnetic particles using specified dispersants which enhance the electrostatic change on the magnetic pigment surface

In the preparation of dispersions of magnetic pigments in organic solvents, dispersants which have a sterically stabilizing effect are used. Milling results in division of the pigment aggregates, which combine again as a result of attractive forces to give secondary agglomerates in the event of poor stabilization. These flocculating materials must be removed from the dispersion by expensive filtration. If an increase in the fineness or pigment batch fluctuations lead to an increase in the secondary agglomerates, filter breakthroughs may occur, resulting in a dramatic reduction in the yield of magnetic recording medium. It was found that excellent dispersion stability is achieved when the magnetic pigments are first precoated with a long-chain dispersant. Subsequently, the use of charge-generating, low molecular weight codispersants, a charge build-up on the pigment is specifically induced by means of bases or acids. The electrostatic repulsion which additionally becomes effective leads to an increase in the dispersion stability. The charges on the pigment are monitored by means of ESA measurements (electrokinetic sound amplitude). These ESA measurements make it possible to establish the order of addition of the dispersants and the optimum amount of codispersant.

Magnetic tape

The magnetic tape includes a magnetic layer containing ferromagnetic hexagonal ferrite powder, abrasive, and binder on a nonmagnetic support, wherein the ferromagnetic hexagonal ferrite powder exhibits an activation volume of less than or equal to 1,800 nm 3 , and inclination, cos θ, of the ferromagnetic hexagonal ferrite powder relative to a surface of the magnetic layer as determined by sectional observation by a scanning electron transmission microscope is greater than or equal to 0.85 but less than or equal to 1.00.

Patent JPS585454B2

Organic fluorine compound

Dispersion of magnetic particles

Patent JPH0121526B2

Metal oxide particle dispersion for manufacturing particulate magnetic recording medium, method of manufacturing magnetic layer-forming composition of particulate magnetic recording medium and method of manufacturing particulate magnetic recording medium

The metal oxide particle dispersion for manufacturing a particulate magnetic recording medium contains metal oxide particles, solvent, and a polyester compound having one or more groups selected from the group consisting of a carboxyl group and a salt thereof, a phosphoric acid group and a salt thereof, a hydroxyl group and a nitrogen-substituted alkylene group, but substantially not containing ferromagnetic powder.

Magnetic recording medium and process

A magnetic recording medium made by coating a base with a magnetic coating material which is a dispersion of magnetic particles in a binder of synthetic resins using a polyfunctional aromatic isocyanate as a curing agent, characterized by the addition of a sorbitan stearate type surface active agent which has a sorbitol derivative in the hydrophilic group. The present magnetic recording medium has superior mechanical properties, especially a superior running quality as well as superior electromagnetic properties.

METHOD FOR PRODUCING MAGNETIC RECORDING CARRIERS

Magnetic recording medium and method of making the same

ABSTRACT OF THE DISCLOSURE A method for making a magnetic tape and a magnetic tape which tape comprises a base or substrate which bears a coating layer of a magnetic powder dispersed in a polymeric binder wherein the improvement concerns the provision of a type of magnetic tape having improved anti-abrasive characteristics. To provide such type tape, there is dispersed in the coating layer thereof in addition to the magnetic powder, a surface active fine powder. Individual particles of this fine powder are coated with a layer of a bound thermoplastic organic polymer. Such a tape exhibit improved Young's Modulus, reduced coefficient of friction on the coating layer, reduced fallen amount of magnetic powder from a tape, reduced magnetic head clogging, improved travelling characteristics, reduced magnetic head abrasion, and the like, singly or in combination.

Process for producing a magnetic recording medium

Magnetic recording medium

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Magnetic recording medium having multiple magnetic layers with specified compositions

A magnetic recording medium comprising a non-magnetic support having thereon a multi-layer magnetic layer structure comprising ferromagnetic fine powder and a binder, wherein said multi-layer magnetic layer structure is formed by coating a first composition containing the ferromagnetic fine powder and a polyisocyanate compound on the non-magnetic support to form a first magnetic layer and coating a second composition containing ferromagnetic fine powder and an epoxy compound having at least one epoxy group or a coupling agent on said first magnetic layer to form a second magnetic layer, wherein coating of said second magnetic layer is conducted simultaneously with or after coating said first magnetic layer while said first magnetic layer is still in a wet state, by a simultaneous or successive multiple layered coating method.

Patent FR2203130A1

Magnetic recording medium

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Phosphorylated reaction products and compositions incorporating such products

NOVEL PHOSPHORYLATED REACTION PRODUCTS AND COMPOSITIONS INCORPORATING SUCH PRODUCTS ABSTRACT Novel phosphorylated compositions of a vinyl chloride copolymer or terpolymer, a phenoxy resin, a hydroxyalkyl acrylate or methacrylate-lactone adduct or a reaction product of a normally solid pendant-hydroxyl-containing thermoplastic polymer having at least 8 hydroxyl groups per molecular chain and an adduct which is the product of either a hydroxylalkyl acrylate or methacrylate or a lactone-acrylate adduct and an organic diisocyanate having improved dispersion characteristics suitable for use in applications such as magnetic recording media.

Process for the preparation of magnetic dispersions containing a binder

1. Process for the production of magnetic, binder-containing dispersions, characterised in that orthoboric acid is added in a quantity of 0.2 to 5.0 parts by weight, based on 100 parts by weight of magnetic pigments, for the grinding of the magnetic pigment dispersion.

Magnetic recording medium and process for its manufacture

New easily dispersible mineral pigments

Magnetic tape and manufacturing method thereof

MAGNETIC REGISTRATION MEDIUM IN WHICH AN N-ACYLSARCOSINE DERIVATIVE IS USED AS A DISPERGENT.

MAGNETIC RECORDING MEDIUM

L'INVENTION CONCERNE UN MILIEU D'ENREGISTREMENT MAGNETIQUE COMPRENANT UN SUPPORT NON MAGNETIQUE ET UNE COUCHE MAGNETIQUE FORMEE SUR CELUI-CI ET COMPOSE PRINCIPALEMENT D'UNE POUDRE MAGNETIQUE ET D'UN LIANT. SELON L'INVENTION, LE LIANT CONTIENT UN COMPOSE REPRESENTE PAR LA FORMULE GENERALE: (CF DESSIN DANS BOPI) DANS LAQUELLE X REPRESENTE UN GROUPE SULFONATE D'AMINE TERTIAIRE OU UN GROUPE ESTER DE SULFATE D'ACIDE D'AMINE TERTIAIRE, Y REPRESENTE UN MONOMERE AYANT UN GROUPE VINYLIQUE QUI EST COPOLYMERISABLE AVEC LE CHLORURE DE VINYLE ET I, J, K REPRESENTENT DES DEGRES DE POLYMERISATION. APPLICATIONS: FABRICATION DE BANDES VIDEO AYANT UNE BRILLANCE DE SURFACE AMELIOREE ET MOINS DE DEBRIS DE POUDRE, MAIS AUSSI DES CARACTERISTIQUES D'ATTENUATION NETTEMENT AMELIOREES. THE INVENTION CONCERNS A MAGNETIC RECORDING MEDIUM INCLUDING A NON-MAGNETIC SUPPORT AND A MAGNETIC LAYER FORMED THEREOF AND MAINLY COMPOSED OF A MAGNETIC POWDER AND A BINDER. ACCORDING TO THE INVENTION, THE BINDER CONTAINS A COMPOUND REPRESENTED BY THE GENERAL FORMULA: (CF DRAWING IN BOPI) IN WHICH X REPRESENTS A TERTIARY AMINE SULPHONATE GROUP OR A TERTIARY AMINE ACID SULPHATE ESTER GROUP, REPRESENTS A MONOMER HAVING A VINYL GROUP WHICH IS COPOLYMERISABLE WITH VINYL CHLORIDE AND I, J, K REPRESENT DEGREES OF POLYMERIZATION. APPLICATIONS: MANUFACTURING VIDEO TAPE WITH IMPROVED SURFACE BRIGHTNESS AND LESS POWDER DEBRIS, BUT ALSO SIGNIFICANTLY IMPROVED MITIGATION CHARACTERISTICS.

PHOSPHORYLATED REACTION PRODUCTS AND COMPOSITIONS CONTAINING SUCH PRODUCTS.

Novel phosphorylated compositions of a vinyl chloride copolymer or terpolymer, a phenoxy resin, a hydroxyalkyl acrylate or methacrylate-­lactone adduct or a reaction product of a normally solid pendant-hydroxyl-containing thermoplastic polymer having at least 8 hydroxyl groups per molecular chain and an adduct which is the product of either a hydroxyalkyl acrylate or methacrylate or a lactone-acrylate adduct and an organic diisocyanate having improved dispersion characteristics suitable for use in applications such as magnetic recording media.

Production of magnetic recording media

Magnetic recording media are produced by dispersing timely divided anisotropic magnetic material in a polymeric binder to a non-magnetizable base.

Magnetic recording body

Reaction product of phosphate-ester and alkoxysilan

Dispersant composition for magnetic media, comprising the reaction product of a phosphate ester and a silicon compound, is described. The silicon compound may be selected from diphenylsilanediol or a trialkoxysilane having alkyl, alkenyl, haloalkyl, acryloxypropyl, methacryloxypropyl or phenyl functionality. A magnetic coating composition and a process for producing a magnetic recording medium having improved magnetic properties, which employ the above dispersant composition, are also disclosed.

A magnetic recording medium

Polymer materials and dispersions containing them

Magnetic compositions

Magnetic recording medium

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Magnetic Coating Composition

1161068 Magnetic compositions SONY CORP 4 Nov 1966 [6 Nov 1965] 49496/66 Index C3B B1 L4H C21 C8R C8B C6X C8P C11 L6G C1 C25 C12 C27 L5X. Index C3R 32 L4H C21 C8R C8B C6X C8P C11 L6G C1 C25 C12 C27 L5X A magnetic coating composition is prepared by dispersing magnetic pigment particles in a vehicle comprising an additive having a dispersing action for the pigment and containing an atomic grouping with active hydrogen or a carboxylic acid group, to form a dispersion, and adding to the dispersion a material capable of reacting with the additive to form a cured epoxy, urethane or urea resin or a mixture or compound of two or more of these resins. The vehicle preferably comprises also a polymeric binder which does not contain active hydrogen atoms or a carboxylic acid anhydride group. In typical Examples, (1) red Hematite is mixed with a polyoxyaminodiol, a vinyl chloride-vinyl acetate copolymer, dioctyl phthalate and methyl ethyl ketone to form a dispersion to which is added a tolylene diisocyanate/methyl ethyl ketone solution, the resulting solution being coated on to the base of a magnetic recording medium; (2) iron oxide of a Fe-Co alloy powder is mixed with a primaryl alkylamine, vinyl chloride-vinyl acetate copolymer, toluene and methyl ethyl ketone to form a dispersion to which is added a second solution comprising ditolylene diisocyanate and methyl ethyl ketone to form a urea resin: (3) iron oxide, diethylene triamine, a vinyl chloridevinyl acetate copolymer, dibutyl phthalate and methyl isobutyl ketone are mixed to form a dispersion to which is added a solution of an epoxy resin in methyl ethyl ketone. Other examples are specified.

METHOD OF MANUFACTURING A MAGNETIC TAPE LACQUER

Magnetic recording element

Magnetic tape and magnetic tape device

【課題】非磁性層と磁性層との合計厚みが０．６０μｍ以下の磁気テープにおいて、タイミングベースサーボシステムにおけるサーボ信号の出力低下を抑制すること。【解決手段】非磁性支持体上に非磁性粉末および結合剤を含む非磁性層を有し、非磁性層上に強磁性粉末および結合剤を含む磁性層を有し、非磁性層と磁性層との合計厚みは０．６０μｍ以下であり、磁性層はタイミングベースサーボパターンを有し、強磁性粉末は強磁性六方晶フェライト粉末であり、磁性層は研磨剤を含み、かつ走査透過型電子顕微鏡を用いて行われる断面観察によって求められる磁性層の表面に対する強磁性六方晶フェライト粉末の傾きｃｏｓθは０．８５以上１．００以下である磁気テープ。磁気テープ装置。【選択図】なし

Magnetic tapes, magnetic tape cartridges and magnetic tape devices

Method of manufacturing magnetic recording medium

MAGNETIC RECORDING MEDIUM

MAGNETIC RECORDING FLUID CONTAINING AS A DERIVATIVE OF N-ACYLSARCOSINE

Magnetic recording medium and process for its manufacture

Heat-assisted magnetic recording medium and magnetic storage device

提供一种热辅助磁记录介质，依次具有基板、底层、及包含具有L1 0 结构的合金的磁性层。磁性层从基板侧开始具有第一磁性层和第二磁性层。第一磁性层和第二磁性层分别具有粒状结构，晶界部处包含C、SiO 2 、及BN。第一磁性层和第二磁性层的晶界部的体积分数分别位于25体积％～45体积％的范围内。第一磁性层的C的体积分数位于5体积％～22体积％的范围内。第一磁性层和第二磁性层的SiO 2 相对于BN的体积比分别位于0.25～3.5的范围内。第二磁性层的SiO 2 的体积分数比第一磁性层的SiO 2 的体积分数大5体积％以上。第二磁性层的BN的体积分数比第一磁性层的BN的体积分数小2体积％以上。

Sulfonate-functional polyester polyols

Sulfonate-functional polyester polyols are derived from reactants comprising an unsaturated polycarboxylic acid or derivative thereof, a polyol, a lactone, and a sulfonating agent. The unsaturated polycarboxylic acid or derivative is substantially free of sulfonate functionality, thereby providing sulfonate-fimctional polyester polyols having low color.The sulfonate-functional polyester palyols are suitable for use, for example, in the manufacture of water-dispersible polyurethanes and polyurethanes used as dispersants for particulate materials, for example, in magnetic recording media.

Magnetic recording medium composition and method of manufacturing magnetic recording medium

The magnetic recording medium composition contains ferromagnetic powder, binder, and a crosslinkable component selected from the group consisting of a component capable of forming a crosslinking structure by a radical reaction, a component capable of forming a crosslinking structure by an ionic reaction, and a component capable of forming a crosslinking structure by a pericyclic reaction, wherein the crosslinkable component contains at least polyester, and the polyester has a weight average molecular weight ranging from 1,000 to 20,000, as well as contains, per molecule, one or more acidic groups, and one or more reactive groups selected from the group consisting of a radical reactive group, an ionic reactive group, and a pericyclic reactive group.

Magnetic recording medium

Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus

The magnetic tape includes a non-magnetic support; and a magnetic layer, in which the magnetic layer has a timing-based servo pattern, an edge shape of the timing-based servo pattern, specified by magnetic force microscopy is a shape in which a difference L99.9−L0.1 between a value L99.9 of a cumulative distribution function of 99.9% and a value L0.1 of a cumulative distribution function of 0.1% in a position deviation width from an ideal shape of the magnetic tape in a longitudinal direction is 180 nm or less, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 or more and 0.40 or less.

Class of dispersants for magnetic recording coatings

ABSTRACT This invention relates to the preparation of the magnetic particle dispersants for improving the high density magnetic recording binder system. The dispersants are prepared by reacting an organophosphate ester or a carboxylated polyester compound with a liquid low molecular weight bisphenol-A epoxy, under a well defined condition to convert the unreacted acid groups to epoxy ester groups. Using this end-product as a dispersion aid in the magnetic coating formulation enhances the loading and dispersibility of the magnetic particles. This dispersant additive also improves the polymer-particle compatibility which further enhances the ink stability and processability for thinner disk coating.

Magnetic recording medium

The present invention provides a magnetic recording medium, in which a binder does not migrates toward the surface of a magnetic layer and which has high durability. Said magnetic recording layer comprises at least one type or more of organic phosphorus compounds selected from the following formulae (1) to (3) and a binder, which contains an amino group or a quaternary ammonium base: where R represents substituted or non-substituted alkyl group, alkenyl group or aryl group, M represents hydrogen atom or alkali metal or ammonium, and n is 1 or 2.

Organic fluorine compounds

Magnetic recording material prodn. using imidazoline cpd. dispersant - giving increased packing density and remanent magnetisation

Prodn. of a magnetic-recording material involves dispersing finely-divided magnetically anisotropic material and usual additives in a soln. of a polymeric binder in an organic solvent, applying it to an unmagnetisable substrate, aligning the magnetic material with a magnetic field and drying and/or hardening. Improvement is that a 2-imidazoline cpd. of formula (I) (where R is 2-20C linear or branched (un)satd. hydrocarbyl; Y is OH or amino) is added as dispersant. The packing density of the particles and hence the remanent magnetisation are increased.

Process for producing a magnetic recording medium

Magnetic recording medium

(57)【要約】本公報は電子出願前の出願データであるた め要約のデータは記録されません。

Hexagonal strontium ferrite powder, magnetic recording medium and magnetic recording / playback device

Magnetic recording medium

Sulfonate-functional polyester polyols

술포네이트-작용성 폴리에스테르 폴리올은 불포화 폴리카르복실산 또는 그의 유도체, 폴리올, 락톤, 및 술폰화제를 포함하는 반응물로부터 유도된다. 불포화 폴리카르복실산 또는 유도체는 술포네이트 작용기가 실질적으로 없고, 이로써 로우 칼라를 갖는 술포네이트-작용성 폴리에스테르 폴리올을 제공한다. 술포네이트-작용성 폴리에스테르 폴리올은 예를 들어 자성 기록 매체의 미립자 물질을 위한 분산제로서 사용되는 폴리우레탄 및 수-분산성 폴리우레탄의 제조시에 사용하기에 적절하다. Sulfonate-functional polyester polyols are derived from reactants comprising unsaturated polycarboxylic acids or derivatives thereof, polyols, lactones, and sulfonating agents. Unsaturated polycarboxylic acids or derivatives are substantially free of sulfonate functionalities, thereby providing sulfonate-functional polyester polyols having a low color. Sulfonate-functional polyester polyols are suitable for use in the production of polyurethanes and water-dispersible polyurethanes used, for example, as dispersants for particulate matter in magnetic recording media. 술포네이트-작용성 폴리에스테르 폴리올, 자성 기록 매체 Sulfonate-functional polyester polyols, magnetic recording media

Method of magnetic metal particle treatment and resulting recording media

Magnetic tape

Magnetic recording medium in which an N-acylsarcosine derivative is used as a dispersing agent

The invention relates to a magnetic recording medium, for example a magnetic tape, which comprises a carrier and a magnetizable coating provided thereon which comprises a binder as well as a magnetic pigment dispersed in the binder by means of a dispersing agent. As a dispersing agent is used an N-acylsarcosine derivative. Herewith an optimum dispersion of the pigment in the binder is obtained in a short dispersion time. An excess of dispersing agent serves as a lubricant upon migration. The acyl group comprises preferably an aliphatic or olefinic hydrocarbon chain having 12-22 carbon atoms. Furthermore are to be preferred salts of N-acrylsarcosine, in particular metal salts, alkali metal salts, alkaline earth metal salts and amine salts.

Dispersion of fine particles of magnetic material

A dispersion of finely divided particles of a magnetic material in an organic liquid containing a dispersant comprising an amine carrying a poly(carbonylalkyleneoxy) chain (PCAO chain) in which the alkylene groups contain up to 8 carbon atoms, or an acid-salt thereof. The dispersion is useful for the preparation of magnetic recording media such as video, audio and computer recording tapes and discs. Certain of the dispersants are novel, especially a polyethyleneimine carrying at least two PCAO chains.

MAGNETIC RECORDING MEDIUM

Magnetic recording medium

Patent JPH0232687B2