MAGNETIC TAPE AND METHOD OF MANUFACTURING THE SAME

• US 20170221517A1
• Filed: 02/02/2017
• Published: 08/03/2017
• Est. Priority Date: 02/03/2016
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: OZAWA, Eiki, OYANAGI, Masahito, KASADA, Norihito
• Granted Patent: US 10,347,279 B2
• Time in Patent Office: Days
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/7356 comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2
• CPC Class Codes: G11B 5/78 Tape carriers
• CPC Class Codes: G11B 5/8404 manufacturing base layers
• CPC Class Codes: G11B 5/8412 treatment by ultrasonics

Abstract

The magnetic tape has a magnetic layer and a backcoat layer, wherein, each of the magnetic layer and 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 FWHM_before on the backcoat layer side surface is greater than 0 nm but less than or equal to 10.0 nm, the FWHM_after on the backcoat layer side surface 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.

Claims

1. 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, S1_after−

S1_before, between a spacing S1_after 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 S1_before 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, S2_after−

S2_before, between a spacing S2_after 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 S2_before 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.

2. The magnetic tape according to claim 1,

wherein the centerline average surface roughness Ra measured on the surface on the magnetic layer side of the magnetic tape is less than or equal to 2.5 nm.

3. The magnetic tape according to claim 1,

wherein the nonmagnetic powder that is contained in the backcoat layer is one or more types of nonmagnetic powder selected from the group consisting of inorganic powder and carbon black.

4. The magnetic tape according to claim 3,

wherein the proportion accounted for by the inorganic powder falls within a range of greater than 50 weight parts to 100 weight parts per 100 weight parts of the total quantity of the nonmagnetic powder contained in the backcoat layer.

5. The magnetic tape according to claim 1,

wherein the full width at half maximum of the 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 5.0 nm.

6. The magnetic tape according to claim 1,

wherein the full width at half maximum of the 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 5.0 nm.

7. The magnetic tape according to claim 1,

wherein the difference, S2_after−

S2_before, falls within a range of 0.5 nm to 6.0 nm.

8. The magnetic tape according to claim 1,

wherein the difference, S1_after−

S1_after, falls within a range of 0.5 nm to 5.0 nm.

9. 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, S1_after−

S1_before, between a spacing S1_after 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 S1_before 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, S2_after−

S2_before, between a spacing S2_after 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 S2_before 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. The method of manufacturing a magnetic tape according to claim 9,

wherein the vibration is ultrasonic vibration.

11. The method of manufacturing a magnetic tape according to claim 9,

wherein, in the magnetic tape, the centerline average surface roughness Ra measured on the surface on the magnetic layer side of the magnetic tape is less than or equal to 2.5 nm.

12. The method of manufacturing a magnetic tape according to claim 9,

wherein, in the magnetic tape, the nonmagnetic powder that is contained in the backcoat layer is one or more types of nonmagnetic powder selected from the group consisting of inorganic powder and carbon black.

13. The method of manufacturing a magnetic tape according to claim 12,

wherein, in the magnetic tape, the proportion accounted for by the inorganic powder falls within a range of greater than 50 weight parts to 100 weight parts per 100 weight parts of the total quantity of the nonmagnetic powder contained in the backcoat layer.

14. The method of manufacturing a magnetic tape according to claim 9,

wherein, in the magnetic tape, the full width at half maximum of the 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 5.0 nm.

15. The method of manufacturing a magnetic tape according to claim 9,

wherein, in the magnetic tape, the full width at half maximum of the 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 5.0 nm.

16. The method of manufacturing a magnetic tape according to claim 9,

wherein, in the magnetic tape, the difference, S2_after−

S2_before, falls within a range of 0.5 nm to 6.0 nm.

17. The method of manufacturing a magnetic tape according to claim 9,

wherein, in the magnetic tape, the difference, S1_after−

S1_after, falls within a range of 0.5 nm to 5.0 nm.