US 10,347,279 B2Granted

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

AssigneeFUJIFILM Corporation

InventorsEiki Ozawa, Masahito Oyanagi, Norihito Kasada

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Abstract

A magnetic tape has a magnetic layer and a backcoat layer. Each of the magnetic layer and the backcoat layer contains a fatty acid ester. The Ra measured on the magnetic layer side surface is less than or equal to 2.8 nm. The difference between the spacing measured by optical interferometry on the magnetic layer side surface after and before vacuum heating is greater than 0 nm but less than or equal to 8.0 nm. The FWHMbefore on the backcoat layer side surface is greater than 0 nm but less than or equal to 10.0 nm. The FWHMafter on the backcoat layer side surface is greater than 0 nm but less than or equal to 10.0 nm. 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.

Claims17

Dependent claims

A magnetic tape,

which comprises a magnetic layer comprising ferromagnetic powder and binder on one surface of a nonmagnetic support and a backcoat layer comprising nonmagnetic powder and binder on the other surface of the nonmagnetic support, wherein:
a centerline average surface roughness Ra measured on a surface on the magnetic layer side of the magnetic tape is less than or equal to 2.8 nm;
the magnetic layer comprises a fatty acid ester;
a difference, S1after−S1before, between a spacing S1after measured by optical interferometry on the surface on the magnetic layer side of the magnetic tape after vacuum heating the magnetic tape and a spacing S1before measured by optical interferometry on the surface on the magnetic 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;
the backcoat layer comprises a fatty acid ester;
a full width at half maximum of a spacing distribution measured by optical interferometry on a 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, S2after−S2before, between a spacing S2after 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 S2before 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 a magnetic layer comprising ferromagnetic powder and binder on one surface of a nonmagnetic support and a backcoat layer comprising nonmagnetic powder and binder on the other surface of the nonmagnetic support, wherein:
a centerline average surface roughness Ra measured on a surface on the magnetic layer side of the magnetic tape is less than or equal to 2.8 nm;
the magnetic layer comprises a fatty acid ester;
a difference, S1after−S1before, between a spacing S1after measured by optical interferometry on the surface on the magnetic layer side of the magnetic tape after vacuum heating the magnetic tape and a spacing S1before measured by optical interferometry on the surface on the magnetic 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;
the backcoat layer comprises a fatty acid ester;
a full width at half maximum of a spacing distribution measured by optical interferometry on a 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, S2after−S2before, between a spacing S2after 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 S2before 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.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/422,944Filed 2 Feb 2017
Priority: JP 2016-0188233 Feb 2016
Published: US 2017/0221517 A13 Aug 2017
Granted: 9 Jul 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 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 5/7356
Characterised by the back layer: comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2
G11B 5/78
Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum: tape carriers