US 10,475,481 B2Granted

Magnetic tape having characterized backcoat layer and method of manufacturing the same

AssigneeFUJIFILM Corporation

InventorsMasahito Oyanagi, Norihito Kasada, Eiki Ozawa

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Abstract

The magnetic tape has a magnetic layer and a backcoat layer. The Ra on the magnetic layer side surface is less than or equal to 1.8 nm, the coefficient of friction measured on the base portion of the magnetic layer side surface is less than or equal to 0.35, and the Ra measured on the backcoat layer side surface is less than or equal to 5.0 nm. The backcoat layer contains a fatty acid ester. In addition, the FWHMbefore measured on the backcoat layer side surface before vacuum heating is greater than 0 nm but less than or equal to 10.0 nm, the FWHMafter after vacuum heating is greater than 0 nm but less than or equal to 10.0 nm, and the difference between the spacing measured on the backcoat layer side surface after and before vacuum heating is greater than 0 nm but less than or equal to 8.0 nm.

Claims19

Dependent claims

A magnetic tape,

which comprises, on one surface of a nonmagnetic support, a magnetic layer comprising ferromagnetic powder and binder, and on the other surface of the nonmagnetic support, a backcoat layer comprising nonmagnetic powder and binder, wherein:
a centerline average surface roughness Ra on a surface on the magnetic layer side of the magnetic tape is less than or equal to 1.8 nm;
a coefficient of friction measured on a base portion of the surface on the magnetic layer side of the magnetic tape is less than or equal to 0.35;
a centerline average surface roughness Ra measured on a surface on the backcoat layer side of the magnetic tape is less than or equal to 5.0 nm;
the backcoat layer comprises a fatty acid ester;
a full width at half maximum of a spacing distribution measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape before vacuum heating the magnetic tape is greater than 0 nm but less than or equal to 10.0 nm;
a full width at half maximum of a spacing distribution measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape after vacuum heating the magnetic tape is greater than 0 nm but less than or equal to 10.0 nm;
and
a difference, Safter−Sbefore, between a spacing Safter measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape after vacuum heating the magnetic tape and a spacing Sbefore measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape before vacuum heating the magnetic tape is greater than 0 nm but less than or equal to 8.0 nm.

6 more elements

A method of manufacturing a magnetic tape,

wherein the magnetic tape is a magnetic tape which comprises, on one surface of a nonmagnetic support, a magnetic layer comprising ferromagnetic powder and binder, and on the other surface of the nonmagnetic support, a backcoat layer comprising nonmagnetic powder and binder, wherein:
a centerline average surface roughness Ra on a surface on the magnetic layer side of the magnetic tape is less than or equal to 1.8 nm;
a coefficient of friction measured on a base portion of the surface on the magnetic layer side of the magnetic tape is less than or equal to 0.35;
a centerline average surface roughness Ra measured on a surface on the backcoat layer side of the magnetic tape is less than or equal to 5.0 nm;
a full width at half maximum of a spacing distribution measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape before vacuum heating the magnetic tape is greater than 0 nm but less than or equal to 10.0 nm;
a full width at half maximum of a spacing distribution measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape after vacuum heating the magnetic tape is greater than 0 nm but less than or equal to 10.0 nm;
and
a difference, Safter−Sbefore, between a spacing Safter measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape after vacuum heating the magnetic tape and a spacing Sbefore measured by optical interferometry on the surface on the backcoat layer side of the magnetic tape before vacuum heating the magnetic tape is greater than 0 nm but less than or equal to 8.0 nm;
and
the method comprises:
coating and drying a backcoat layer-forming composition comprising nonmagnetic powder, binder, and a fatty acid ester on one surface of a nonmagnetic support to form a coating layer;
and
applying vibration to the coating layer that has been formed to form a backcoat layer.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/422,821Filed 2 Feb 2017
Priority: JP 2016-0188213 Feb 2016
Published: US 2017/0221516 A13 Aug 2017
Granted: 12 Nov 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G11B 5/8412
Processes or apparatus specially adapted for manufacturing record carriers: treatment by ultrasonics
G11B 5/70
Comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent: on a base layer
G11B 5/7358
Comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2: specially adapted for achieving a specific property,…
G11B 5/78
Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum: tape carriers